Name: high throughput characterization of adult stem cells engineered for delivery of therapeutic factors for neuroprotective strategies
Uploaded: 2015-01-04T14:00:00
Duration: 9 min 19 s
Description: Watch this Scientific Journal Video about High Throughput Characterization of Adult Stem Cells Engineered for Delivery of Therapeutic Factors for Neuroprotective Strategies at JoVE.com

Funding for this research was provided by the US Army Medical Research and Materiel Command (Grant account no. W81XWH-11-1-0700) and the Stem Cell Research Fund. PAB and EMP were recipients of Ames Laboratory Summer Undergraduate Laboratory Internships (SULI).

1. Substrate Preparation for 96-well Plates
<ol>
	<li>Create a map of the 96-well plate outlining the different substrates and cell-types to be examined (Figure&#160;1).</li>
	<li>Obtain the stock solutions of different substrates [poly-L-lysine, fibronectin, collagen type I, laminin, and entactin-collagen IV-laminin (ECL)], a 96-well multiwell plate and prepare a work station in a sterile cell culture hood.</li>
	<li>Prepare individual substrates by diluting stock in sterile phosphate buffered saline (PBS) to a final concentration of 5 &#181;g/ml (this concentration was previously determined based on a substrate concentration-dependent assay for growth and proliferation of cells). Mix using a vortex before pouring into a sterile reservoir.</li>
	<li>Add 100 &#181;l of substrate solution into each well according to the 96-well map (Figure 1) (a 12- or 8-channel micropipette is convenient for micropipetting into a 96-well plate). Seal the lid to the 96-well plate using a strip of Parafilm and store overnight at 4 &#176;C.</li>
</ol>
2. Cell Plating and Time-lapse Imaging
NOTE: Mouse MSCs were isolated from the bone marrow of adult C57BL/6 mice and maintained as an adherent cell line. MSCs were infected using lentiviral vectors to engineer them to secrete brain-derived neurotrophic factor (BDNF; human cDNA) and glial cell-derived neurotrophic factor (GDNF; human cDNA) using lentiviral vector&#8217;s encoding BDNF (LV-BDNF; CMV-BDNF-IRES-GFP), GDNF (LV-GDNF; CMV-GDNF-IRES-GFP), and green fluorescent protein (GFP, LV-GFP; CMV-GFP). 
NOTE: Culture media for mouse mesenchymal stem cells (MSCs) is Iscove&#39;s Modified Dulbecco&#39;s Medium containing 10% hybridoma-qualified fetal bovine serum, 10% equine serum, 2 mM L-glutamine, and 10,000 U/ml penicillin, 10 mg/ml streptomycin. The five different types of mouse MSCs (MSCs, GFP-MSCs, BDNF-GFP-MSCs, GDNF-GFP-MSCs and BDNF/GDNF-GFP-MSCs) were plated at about 30% confluence in T75 cell culture flasks.
<ol>
	<li>Cell Plating
	<ol>
		<li>On the following day, remove the substrate solutions by aspiration and rinse each well with approximately 200 &#181;l of sterile PBS, twice. Add cell culture media (200 &#181;l/well) to each well after the final PBS rinse. Place the 96-well plate into a cell culture incubator set at 37 &#176;C and 5% CO2 for equilibration.</li>
		<li>While the 96-well plate is equilibrating in the incubator, harvest the cells (MSCs in T75 flasks should be approximately 70% confluent at time of harvesting/plating) by collecting the growth media (referred to as conditioned media) from the T75 flask and storing in a 15 ml conical tube under sterile conditions (this conditioned media will be used in step 2.1.4 below).</li>
		<li>Add 8 ml of sterile PBS to the flask and gently swirl and then pipette off the PBS and add 1 ml of 0.05% trypsin and 0.01% EDTA solution to detach the cells from the culture surface of the T75 flask. Monitor cell detachment by viewing the flask using an inverted microscope equipped with phase contrast optics.</li>
		<li>When the cells have detached, immediately add 8 ml of the conditioned media (collected in step 2.1.2) to the flask. Collect the cell suspension and transfer to a 15 ml conical centrifuge tube and centrifuge for 4 min at 450 x g to pellet the cells.</li>
		<li>Remove the supernatant and resuspend the cell pellet in 200 &#181;l of fresh and warmed (37 &#176;C) cell culture media.</li>
		<li>Determine the number of cells in the cell suspension by performing a trypan blue viable cell count using a hemocytometer. Plate the cells at a density of approximately 300 cells/well into the appropriate wells of the 96-well plate.</li>
		<li>Repeat these steps for each population of cells.</li>
	</ol>
	</li>
	<li>Time-lapse Imaging
	<ol>
		<li>Once all of the MSCs have been plated, place the 96-well plate into an incubator for 2 hr to allow the MSCs to attach to the substrate.</li>
		<li>Start the HCS system and wait for 2 hr for the system to equilibrate. Set the environmental controller to 37 &#176;C and connect a mixed gas cylinder containing 5% CO2 in air to the HCS system environmental chamber supplying a constant air source.</li>
		<li>Remove the 96-well plate from the incubator following the 2 hr equilibration period and place directly into the cell growth chamber of the HCS system. Allow 30 min for equilibration to account for any heat-related expansion of the plate and then start the image acquisition and analysis software to configure the plate settings.</li>
		<li>Select the 20X objective for imaging. Select two wells per condition [i.e., GFP-MSCs on Fibronectin etc. (6 substrates x 5 MSC subtypes for a total of 30 conditions x 2 replicates = 60 wells in total)] for setting up time-lapse imaging. Choose two sites for imaging within each well.</li>
		<li>Choose the correct light wavelengths for imaging. 
		NOTE: Two different wavelengths (Phase contrast and GFP fluorescence) were selected for time-lapse imaging.</li>
		<li>Focus on the well bottom using laser autofocus and take test images for multiple sites and multiple wells to find an optimized focal plane.</li>
		<li>Once the focus has been established, begin capturing images every 5 min for 48 hr for all 60 wells (120 sites).</li>
		<li>Feed the cells every 24 hr by removing the 96-well plate from the HCS system. Remove 75 &#181;l of media from each well and add 100 &#181;l of fresh media to each well (equilibrate this fresh media at 37 &#176;C and 5% CO2).</li>
		<li>At the end of the time-lapse experiment, remove the 96-well plate from the HCS system. Under sterile conditions, collect the conditioned media samples from each well and transfer these samples to another 96-well plate. 
		NOTE: These samples can be used for further analysis by performing ELISA for neurotrophic factors.</li>
		<li>Prepare the 96-well plate with cultured MSCs for additional assays such as Ki67 cell proliferation assay or propidium iodide live/dead staining assay (see details below).</li>
		<li>Perform time-lapse imaging analysis for cell migration/cell tracking as described in section 5 below.</li>
	</ol>
	</li>
</ol>
3. Ki67 Cell Proliferation and Propidium Iodide Live/Dead Assay
<ol>
	<li>Ki67 Cell Proliferation Assay (Immunocytochemistry)
	<ol>
		<li>Rinse the cell cultures with 0.1 M phosphate (PO4) buffer for one minute two times. Fix the culture with 4% paraformaldehyde (PFA) for 20 min at room temperature. Remove the PFA and rinse the wells with PBS for seven minutes three times.</li>
		<li>After the final rinse, add 100 &#181;l of blocker solution (phosphate buffer saline, 5% normal donkey serum, 0.4% bovine albumin serum, and 0.2% Triton X-100) to each well and incubate at room temperature for 1 hr. Prepare the primary antibody, rabbit anti-Ki67, by diluting in blocker solution at a working ratio of 1:200.</li>
		<li>Remove the blocker solution and apply 100 &#181;l of the primary antibody solution to each well. Cover the 96-well plate and incubate the samples at 4 &#176;C overnight.</li>
		<li>On the following day, remove the antibody solution and rinse with PBS for 7 min, 3 times.</li>
		<li>Prepare the secondary antibody, donkey anti-rabbit Cy3 in blocking solution at a working ratio of 1:500. Add DAPI nuclear stain to the secondary antibody solution at a dilution of 1:100. After the removal of the last PBS rinse, apply 100 &#181;l of the secondary antibody/DAPI solution to each well. Incubate at room temperature in the dark for 90 min.</li>
		<li>Remove the secondary antibody/DAPI solution and rinse each well with PBS for 7 min, 3 times. Cover the 96-well plate and store at 4 &#176;C until imaging.</li>
	</ol>
	</li>
	<li>Propidium Iodide Live/Dead Assay
	<ol>
		<li>Measure cell death by propidium iodide (PI) exclusion assay as described below.</li>
		<li>Prepare the propidium iodide stain solution at a concentration of 1.5 &#181;M in culture media.</li>
		<li>Add 100 &#181;l of 70% ethanol to one well of the MSCs for 2 min with the intention of killing those cells. This well serves as a positive control for the PI stain. The majority of the MSCs will be PI-stained indicating cell death. Remove the ethanol solution.</li>
		<li>Add 100 &#181;l of propidium iodide stain solution to each well and incubate for 20 min at 37 &#176;C in a 5% CO2 incubator.</li>
		<li>Rinse the cells with 0.1 M phosphate buffer for 1 min, 2 times. Fix the cells with 4% PFA in 0.1 M P04 buffer for 20 min at room temperature. Remove the PFA and rinse with PBS three times for 7 min.</li>
		<li>Incubate with DAPI solution (1:50) diluted in blocker solution for 1 hr at room temperature. Rinse all wells with PBS for 7 min, 3 times.</li>
		<li>Remove the DAPI solution and rinse each well with PBS for 7 min, 3 times. Cover the 96-well plate and store at 4 &#176;C until imaging.</li>
	</ol>
	</li>
</ol>
4. Automated Imaging and Multiwavelength Scoring Analysis
<ol>
	<li>Load a 96-well plate (previously processed for Ki67 immunolabeling or propidium iodide-stained) into the HCS system and allow the plate to equilibrate for 20 min Open the HCS system image acquisition and analysis software.</li>
	<li>Choose the acquisition settings for the 10X objective using camera binning at 1 and a gain setting of 2. Find the Z-plane in which the cells reside by utilizing the Auto Exposure function and calculate the offset for each wavelength of interest. For this analysis, capture images for DAPI (W1), Cy3 (W2), and FITC (W3). Choose the maximum intensity level at which the negative control wells show no signal for image acquisition. Confirm this setting is appropriate for the positive wells.</li>
	<li>Acquire plate. Capture images and store them in the image acquisition and analysis software&#8217;s database.</li>
	<li>Once images have been acquired, open image acquisition and analysis offline software and review plate data from the images acquired above.</li>
	<li>Select the Multi-wavelength scoring analysis. Configure the minimum and maximum intensities for each wavelength. 
	NOTE: DAPI detection should mark the staining around each visible nucleus. Cy3 should detect the positive cells with Ki67 immunoreactivity (IR) and should not detect IR under the negative controls. For Cy3 Ki67 IR, the approximate minimum width was 7 &#181;m, approximate maximum width was 30 &#181;m, the intensity above the local background was 150 gray levels, and the minimum stained area was 50 &#181;m2.</li>
	<li>Run analysis for all positions. Export the data to view in spreadsheet.</li>
</ol>
5. Cell Tracking
<ol>
	<li>Open image acquisition and analysis program and click on &#8220;Review Plate Data [DB]&#8230;&#8221;, selecting the plate of interest.</li>
	<li>View the data as &#8220;Time vs. Well&#8221;.</li>
	<li>Choose one of the sites from the &#8220;Sites&#8221; section by left clicking on the desired selection. Select &#8220;Transmitted&#8230;&#8221; under the &#8220;Wavelengths:&#8221;. Right click on the target well in the 96-well plate template and click on &#8220;Load Images&#8221;.</li>
	<li>Track the cells by clicking on the &#8220;Apps&#8221; and then &#8220;Track Objects&#8221;.</li>
	<li>Use &#8220;Dynamic Data Exchange (DDE)&#8221; to choose the format to export the data, e.g., Microsoft Excel.</li>
	<li>Choose the tracking data to export, e.g., elapsed time, object number, distance, time interval, velocity, absolute angle, distance to origin, delta x and delta y.</li>
	<li>Tag each cell of interest with &#8220;Ctrl key + left click&#8221; on target cells.</li>
	<li>Track cells. If necessary, stop/change improper tracking of cells with the &#8220;Esc&#8221; key and then adjust the settings.</li>
	<li>After cell tracking is complete, save data with &#8220;Log Data&#8221;.</li>
</ol>

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Publication fees for this video article were supported by Molecular Devices, LLC.

Adult mesenchymal stem cells (MSCs) are an attractive cell type for development of an experimental strategy combining a cellular and gene delivery based therapy. MSCs are multipotent, capable of differentiating into cells of mesodermal lineage, and display considerable plasticity, differentiating/transdifferentiating into neuronal and glial lineages with the appropriate induction paradigms17,18. Furthermore, MSCs have been transplanted and proven effective in preclinical studies for a number of disorders, including neurodegenerative conditions19. The therapeutic efficacy of MSCs is well known due to their beneficial anti-proliferative, anti-inflammatory and anti-apoptotic activities20. MSCs are also known to produce and secrete various neurotrophic and growth factors, which likely contributes to the neuroprotective qualities associated with na&#239;ve MSCs following transplantation at sites of injury or disease21. Importantly, MSCs can be genetically modified for sustained delivery of neurotrophic factors for combined cellular and gene therapy-based applications and have been used in a number of animal models of injury or disease to the CNS11,19,22.
In developing a combined cellular and gene therapy-based strategy, it is important that the health of the cells is carefully assessed prior to their extensive use for in vitro, and especially in vivo applications. As a proof of concept, we investigated multiple populations of engineered and control MSC lines in order to study the consequences of the genetic modifications on cell health and fitness using a high content screening (HCS) approach. In general, HCS refers to cellular image-based high throughput screening14. This screening approach permits a quantitative assessment of cellular phenotypes at multiple levels of spatial (cell to subcellular) and temporal (milliseconds to days) resolution across various experimental conditions. Using this approach we accessed possible differences in substrate preference on the following parameters: cell proliferation, expression of green fluorescent protein (GFP), cell death, and cell motility/migration. Experiments were designed in 96-well cell culture plate format. Within a single plate we routinely investigated possible substrate-related differences with respect to each parameter for the different MSC populations of lentiviral-transduced cells and compared the engineered MSCs with the original, non-transduced MSCs. This provided a means to directly compare the results for the different MSC subtypes with a battery of in vitro assays such as cell proliferation using Ki67 immunolabeling, live/dead cell viability assay using propidium iodide staining, and cell behavior by performing time-lapse digital imaging. As an extension of this HCS one can also perform ELISAs on conditioned media samples collected from individual wells to quantitatively determine secretion of neurotrophic factors. Conditioned media from different MSC subtypes may also be used in in vitro bioassays to determine biological activity of secreted factors11,23. This type of HCS platform may also be used for in vitro measurements of neurite outgrowth from primary neuronal cultures and neural stem cell lines24. Overall, our results demonstrated that the subpopulations of the genetically modified MSCs displayed similar behaviors in comparison to the non-modified MSCs. The influence of diverse culture substrates on cell growth and cell migration was not dramatically different between the MSC subtypes, as well as culture substrates. As such, the extracellular matrix substrates tested did not appear to play a critical role in modulating these aspects of cell behavior for these different engineered MSCs.
This study demonstrates the use of an HCS system for analyzing different aspects of cell behavior. However, it is not uncommon to encounter limitations associated with image analysis. On occasion, while analyzing the fluorescence images, it was somewhat difficult to determine the correct threshold value above which immunolabeled or stained cells would be counted as positively labeled/stained. Thus, to minimize subjective bias, the determination of threshold values was dependent upon a comparison with controls (negative controls for fluorescence imaging were carried out in parallel during all processing by the omission of the primary or secondary antibodies). Another limitation was encountered during the analysis of cell migration using time- lapse digital imaging. In some cases, the imaging software was not able to differentiate between random Brownian motion of a cell versus a cell actually migrating only a very short distance. Additional limitations were evident in situations where the analysis software was not able to distinguish the presence of multiple cells in very close proximity to one-another. To overcome this limitation required manual cell selection during the analysis rather than a fully automated analysis. Cell plating density can also result in skewing cell migration data between populations of cells that display greater preference to grow in clumps versus cells that grow in isolation from each other. These types of differences are in part likely a reflection of cell-substrate versus cell-cell preferences.
Using an HCS system to acquire images and perform data analysis provides an efficient and rapid means to assess multiple cell parameters. In addition, time-lapse digital videos for 30 different conditions (6 substrates and 5 different MSC subtypes) were routinely acquired for periods ranging from hours to days (48 hr) while using the environmental chamber. This data was subsequently used to calculate and determine differences in cell migration rates across various cell lines on different ECM molecules.
In this report we have highlighted the implementation of a high content screening platform to assess cell health and function. This type of analysis is useful for developing rational strategies for designing cell-types, as well as polymer substrates to facilitate directed cell growth and neural regeneration. This is an essential step towards application of stem cell-based delivery of therapeutic factors prior to extensive in vivo preclinical studies using cell transplantation strategies.

A major issue with implementing useful therapies for treatment of nervous system disorders is in developing effective methods that prevent further degeneration and also facilitate recovery of function. An innovative strategy is to genetically engineer stem cells ex vivo, for production of neuroprotective factors, prior to their transplantation. This combination of cell-based therapy, coupled with a type of gene therapy, provides a powerful method for the treatment of disease or injury-induced neuronal death in the nervous system.
Neurotrophic factors are essential for growth and survival of developing neurons as well as maintenance and plasticity of mature neurons. A number of studies have demonstrated significant roles of neurotrophic factors in promoting initial growth and differentiation of neurons in the central and peripheral nervous system (CNS and PNS) and they can also stimulate regeneration in vitro and in animal models of neural injury1. Brain-derived neurotrophic factor (BDNF) is highly expressed in the CNS and plays important roles in regulating neural development, synaptic plasticity and repair2. Glial cell line-derived neurotrophic factor (GDNF) promotes survival of many types of neurons including dopaminergic and motorneurons3. Thus, an important strategy for neural repair is to provide exogenous sources of neurotrophic factors to the injured or diseased regions of the nervous system.
Multipotent bone marrow-derived mesenchymal stem cells (MSCs) hold great potential for delivery of therapeutic proteins to treat the damaged or diseased nervous system. Transplantation of MSCs has attracted considerable attention in efforts to develop patient compatible cell-based therapies since they have a number of advantages including, 1) relative ease of isolation and maintenance, 2) multipotential capacity, 3) little ethical concerns, 4) ability to survive and migrate following transplantation and 5) potential for autologous transplantation4,5. Promising results have been reported with use of na&#239;ve and genetically engineered MSCs in animal models for a number of different neurodegenerative conditions, including spinal cord injury6,7, stroke8,9, myelin deficiency10, and retinal degeneration11-13. Coupling cell transplantation with delivery of neurotrophic factors from genetically engineered stem cells is a novel and important neural repair strategy.
An essential step in developing cell-based therapeutic factor delivery systems is to determine the normal health of the engineered cells. As such, the principal purpose of this study was to evaluate general growth parameters of genetically engineered adult stem cells. An important approach to rapidly assess multiple cell parameters is to employ cellular image-based high-through screening (HTS), often referred to as high content screening (HCS) procedures14. This technology allows automated image acquisition and analysis and this approach is particularly well suited for stem cell research applications. In this project we developed a profiling platform that allows for the rapid characterization and optimization of cell substrate preferences and cellular functions with genetically engineered adult stem cells employing a HCS system.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>96 well plates</td>
			<td>Greiner Bio One</td>
			<td>655090</td>
			<td>96 well plates selected for use in ImageXpress</td>
		</tr>
		<tr>
			<td>Bovine serum albumin (BSA)</td>
			<td>Sigma-Aldrich (St. Louis, MO)</td>
			<td>A9647</td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit anti-Ki67 antibody</td>
			<td>Abcam (Cambridge, MA)</td>
			<td>Ab16667</td>
			<td>1:200 dilution</td>
		</tr>
		<tr>
			<td>Collagen type I</td>
			<td>Sigma-Aldrich (St. Louis, MO)</td>
			<td>C7661</td>
			<td>Collagen from rat tail</td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Invitrogen (Carlsbad, CA)</td>
			<td>D3571</td>
			<td></td>
		</tr>
		<tr>
			<td>Donkey anti-Rabbit Cy3</td>
			<td>Jackson Immuno Res Lab (West Grove, PA)&#160;</td>
			<td>711-165-152</td>
			<td>1:500 dilution</td>
		</tr>
		<tr>
			<td>ECL(Entactin-Collagen-Laminin)</td>
			<td>Millipore/Chemicon (Temecula, CA)</td>
			<td>08-110</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal bovine serum (FBS)</td>
			<td>Hyclone (Logan, UT)</td>
			<td>SH30071.03</td>
			<td></td>
		</tr>
		<tr>
			<td>Equine serum</td>
			<td>Hyclone (Logan, UT)</td>
			<td>SH3007403</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Chemistry Store (Ames, IA)</td>
			<td>12003510</td>
			<td>100%, 200 proof</td>
		</tr>
		<tr>
			<td>Fibronectin</td>
			<td>Fisher Scientific (Hampton, NH)</td>
			<td>CB-40008</td>
			<td></td>
		</tr>
		<tr>
			<td>Iscove&#8217;s Modified Dulbeccos Medium (IMDM)</td>
			<td>Hyclone (Logan, UT)</td>
			<td>SH30396.03</td>
			<td></td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Fisher Scientific (Hampton, NH)</td>
			<td>P285</td>
			<td>For PO4 buffer</td>
		</tr>
		<tr>
			<td>K2HPO4</td>
			<td>Fisher Scientific (Hampton, NH)</td>
			<td>P288</td>
			<td>For PO4 buffer</td>
		</tr>
		<tr>
			<td>L-Glutamine</td>
			<td>Gibco/Invitrogen (Grand Island, NY)</td>
			<td>25030-081</td>
			<td></td>
		</tr>
		<tr>
			<td>Laminine (mouse)</td>
			<td>Trevigen (Gaithersburg, MD)</td>
			<td>3400-010-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse MSCs of adult C57BL/6 mice</td>
			<td>Tulane Cent for Gene Therapy (New Orleans, LA)</td>
			<td></td>
			<td>Isolated from bone marrow</td>
		</tr>
		<tr>
			<td>Genetically modified MSCs (GFP, BDNF, GDNF, BDNF/GDNF)</td>
			<td>These cells were obtained from our previous study : Ye et. al. (in preparation)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Normal donkey serum (NDS)</td>
			<td>Jackson Immuno Res Lab (West Grove, PA)&#160;</td>
			<td>017-000-121</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde (PFA)</td>
			<td>Fisher Scientific (Hampton, NH)</td>
			<td>O4042</td>
			<td>4% PFA in 0.1M PO4 buffer</td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Sigma-Aldrich (St. Louis, MO)</td>
			<td>P0781</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate buffered saline (PBS)</td>
			<td>Sigma-Aldrich (St. Louis, MO)</td>
			<td>P4417</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly-L-lysine</td>
			<td>Sigma-Aldrich (St. Louis, MO)</td>
			<td>P4707</td>
			<td></td>
		</tr>
		<tr>
			<td>Propidium iodide (PI)</td>
			<td>Invitrogen (Carlsbad, CA)</td>
			<td>P1304MP</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma-Aldrich (St. Louis, MO)</td>
			<td>X100</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin 0.05% (EDTA 1X)</td>
			<td>Invitrogen (Carlsbad, CA)</td>
			<td>25300-054</td>
			<td></td>
		</tr>
		<tr>
			<td>Iscove&#39;s Modified Dulbecco&#39;s Medium</td>
			<td>Invitrogen (Carlsbad, CA)</td>
			<td>12440&#8211;046</td>
			<td></td>
		</tr>
		<tr>
			<td>Hybridoma-qualified FBS</td>
			<td>Hyclone (Logan, UT)</td>
			<td>SH30396.03</td>
			<td></td>
		</tr>
		<tr>
			<td>Equine serum</td>
			<td>Hyclone (Logan, UT)</td>
			<td>SH3007403</td>
			<td></td>
		</tr>
		<tr>
			<td>ImageXpress Micro</td>
			<td>Molecular devices (Sunnyvale, CA)</td>
			<td>ImageXpress micro</td>
			<td>High content screening system</td>
		</tr>
		<tr>
			<td>MetaXpress 4.0</td>
			<td>Molecular devices (Sunnyvale, CA)</td>
			<td>MetaXpress 4.0</td>
			<td>Image acquisition and analysis software</td>
		</tr>
	</tbody>
</table>

high throughput characterization of adult stem cells engineered for delivery of therapeutic factors for neuroprotective strategies

Mesenchymal stem cells (MSCs) derived from bone marrow are a powerful cellular resource and have been used in numerous studies as potential candidates to develop strategies for treating a variety of diseases. The purpose of this study was to develop and characterize MSCs as cellular vehicles engineered for delivery of therapeutic factors as part of a neuroprotective strategy for rescuing the damaged or diseased nervous system. In this study we used mouse MSCs that were genetically modified using lentiviral vectors, which encoded brain-derived neurotrophic factor (BDNF) or glial cell-derived neurotrophic factor (GDNF), together with green fluorescent protein (GFP). 
Before proceeding with in vivo transplant studies it was important to characterize the engineered cells to determine whether or not the genetic modification altered aspects of normal cell behavior. Different culture substrates were examined for their ability to support cell adhesion, proliferation, survival, and cell migration of the four subpopulations of engineered MSCs. High content screening (HCS) was conducted and image analysis performed. 
Substrates examined included: poly-L-lysine, fibronectin, collagen type I, laminin, entactin-collagen IV-laminin (ECL). Ki67 immunolabeling was used to investigate cell proliferation and Propidium Iodide staining was used to investigate cell viability. Time-lapse imaging was conducted using a transmitted light/environmental chamber system on the high content screening system.
Our results demonstrated that the different subpopulations of the genetically modified MSCs displayed similar behaviors that were in general comparable to that of the original, non-modified MSCs. The influence of different culture substrates on cell growth and cell migration was not dramatically different between groups comparing the different MSC subtypes, as well as culture substrates. 
This study provides an experimental strategy to rapidly characterize engineered stem cells and their behaviors before their application in long-term in vivo transplant studies for nervous system rescue and repair.

MSC growth parameters were examined by culturing the different populations of MSCs on different substrates. The five different populations of MSC subtypes (MSCs, GFP-MSCs, BDNF-GFP-MSCs, GDNF-GFP-MSCs, and BDNF/GDNF-GFP-MSCs) were plated into 96-well tissue culture plates pre-coated with the different substrates as illustrated in Figure 1. After four days of culturing, the plates were fixed and immunolabeled and/or stained with the appropriate reagents and then examined using the HCS system and analyses conducted with the image acquisition and analysis software program.
<img alt="Figure 1" src="/files/ftp_upload/52242/52242fig1highres.jpg" width="650" /> 
Figure 1: 96-well plate template for experimental design. 96-well plates were coated with various substrates and wells were seeded with engineered stem cells as shown in the template. As an example, only wells in rows B-F were used in this experiment. Rows A, G and H were left empty. Abbreviations &#8211; MSCs: mesenchymal stem cells; GFP-MSCs: green fluorescent protein-expressing MSCs; BDNF-GFP-MSCs: brain derived neurotrophic factor-GFP-expressing MSCs; GDNF-GFP-MSCs; Glial cell-derived neurotrophic factor-GFP-expressing MSCs; BDNF/GDNF-GFP-MSCs; BDNF and GDNF- GFP-expressing MSCs; ECL: Entactin-Collagen IV-Laminin).
Anti-Ki67 immunolabeling, followed by DAPI counterstaining, was used to evaluate whether the different substrates influenced proliferation of the different populations of engineered MSCs (Figure 2A). Expression of the Ki67 antigen occurs preferentially during late G1, S, G2 and M phases of the cell cycle, and is not detected in cells in the resting phase (G0), and therefore is useful as a cellular marker for proliferation15. 4&#39;,6-diamidino-2-phenylindole (DAPI) is a commonly used nuclear and chromosome counterstain that emits blue fluorescence upon binding to AT regions of DNA16. The total number of cells in a field can be determined by counting the number of DAPI stained nuclei. As illustrated in Figure 2B, although there was variation in the percentages of proliferating MSCs, all substrates nevertheless supported considerable cell proliferation for each of the MSC subtypes.
<img alt="Figure 2" src="/files/ftp_upload/52242/52242fig2highres.jpg" width="700" /> 
Figure 2: Ki67 cell proliferation assay. (A) Merged, double-fluorescent image of Ki67 immunolabeling (red) and DAPI (blue) nuclear staining. Many of the MSCs were immunolabeled with the Ki67 antibody (red). Scale bar = 50 &#181;m. (B) Bar graph illustrating the percentages of Ki67 immunolabeled MSC subtypes grown on polystyrene (PS), poly-L-lysine (PLL), fibronectin, collagen type I, laminin, or entactin-collagen IV-laminin (ECL) substrates for 5 days in vitro (DIV). N = one experiment. Each bar represents averaged pooled data from 8 imaged sites from 2 wells for each condition. <a href="https://www.jove.com/files/ftp_upload/52242/52242fig2highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Propidium iodide (PI) staining was used to evaluate whether different substrates influenced cell survival (Figure 3). Propidium iodide is a commonly used red-fluorescent nuclear and chromosome counterstain. Propidium iodide is membrane impermeant and generally excluded from viable cells, and thus is useful to detect dead cells in a population. The proportion of dead cells within a given condition can be determined when combined with a general nuclear label such as DAPI to identify all cells within a field. The percentage of PI-positive cells was low on all substrates examined (Figure 3). As a positive control for the PI reagent, a few wells containing MSCs were incubated in 70% ethanol, a condition known to kill most cells, resulting in a high percentage of PI-labeled cells as illustrated in Figure 3B and 3C (ethanol treated positive control).
<img alt="Figure 3" src="/files/ftp_upload/52242/52242fig3highres.jpg" width="700" /> 
Figure 3: Propidium iodide cell death assay. (A) Merged, double fluorescent image for propidium iodide (red) and DAPI (blue) staining. Although the nuclei of all of the viable cells were stained with DAPI (blue), no propidium iodide staining was detected in the MSCs. (B) Virtually all MSCs were stained with propidium iodide following exposure to 70% ethanol. Scale bars in A and B = 100 &#181;m. (C) Bar graph illustrating the percentages of propidium iodide (PI) stained MSC subtypes grown on polystyrene (PS), poly-L-lysine (PLL), fibronectin, collagen type I, laminin, or entactin-collagen IV-laminin (ECL) substrates for 5 days in vitro (DIV). Ethanol Control: This condition served as a positive control for the PI staining reagent. Most cells subjected to PI stain following ethanol treatment are dead and thus positively stained for the PI reagent. N = one experiment. Each bar represents averaged pooled data from 8 imaged sites from 2 wells for each condition. <a href="https://www.jove.com/files/ftp_upload/52242/52242fig3highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
To investigate the possible influence of different substrates on the behavior of engineered MSCs, cell migration was analyzed using time-lapse digital microscopy and the transmitted light/environmental chamber system on the HCS system (see Supplemental Video 1). Multiple sites/well were time-lapse imaged and used to calculate cell migration rates for the different subpopulations of MSCs growing on the different substrates using the image acquisition and analysis software program. In general, as shown in Figure 4C, all subtypes of MSCs showed the fastest migration rate on the extracellular matrix-coated surfaces (Fibronectin, Collagen, Laminin and ECL) and the slowest on non-coated polystyrene surfaces.
<img alt="Figure 4" src="/files/ftp_upload/52242/52242fig4highres.jpg" width="700" /> 
Figure 4: Cell tracking and migration. MSCs tracked with image acquisition and analysis software. Overlayed images of transmitted light and fluorescence images from (A) the start of time-lapse imaging and (B) at 29 hr later at the end of the time-lapse imaging session (see Supplemental Video 1). Cell migration tracks are indicated by the colored lines. Scale bar: 50 &#181;m. (C) Bar graph illustrating the average migration rates (expressed as &#181;m/hr) for MSC subtypes grown on polystyrene (PS), poly-L-lysine (PLL), fibronectin, collagen type I, laminin, or entactin-collagen IV-laminin (ECL) substrates for 2 days in vitro (DIV). N = one experiment. Each bar represents the average of at least 10 imaged cells from 2 wells for each condition. <a href="https://www.jove.com/files/ftp_upload/52242/52242fig4highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Taken together, these results provide preliminary evidence that these subpopulations of genetically engineered MSCs display similar growth properties. These results provide compelling evidence that the lentiviral mediated genetic modifications of these MSCs induced no dramatic detectable deleterious effects on the growth parameters investigated using this screening platform.
Supplemental Video 1. Time-lapse digital video of MSC tracking using the image acquisition and analysis software program. The migration path&#8217;s for two MSCs [indicated as 1 (green tracking line) and 2 (Blue tracking line)] are illustrated. Video captured during a 29 hr period. Images were captured every 5 min. Fluorescence images of GFP-expressing MSCs was used for time-lapse imaging in preparing the video. Calibration bar = 50 &#181;m. This type of analysis is useful for investigating cell behaviors, including cell migration and cell division.

Watch this Scientific Journal Video about High Throughput Characterization of Adult Stem Cells Engineered for Delivery of Therapeutic Factors for Neuroprotective Strategies at JoVE.com

High Throughput Characterization of Adult Stem Cells Engineered for Delivery of Therapeutic Factors for Neuroprotective Strategies

This study describes an experimental platform to rapidly characterize engineered stem cells and their behaviors before their application in long-term in vivo transplant studies for nervous system rescue and repair.

Mesenchymal stem cells (MSCs) derived from bone marrow are a powerful cellular resource and have been used in numerous studies as potential candidates to ...

high-throughput-characterization-adult-stem-cells-engineered-for

Research

JoVE Journal

Medicine

A High-throughput Automated Platform for the Development of Manufacturing Cell Lines for Protein Therapeutics

The fast-growing biopharmaceutical industry demands speedy development of highly efficient and reliable production systems to meet the increasing requirement for drug supplies. The generation of production cell lines has traditionally involved manual operations that are labor-intensive, low-throughput and vulnerable to human errors. We report here an integrated high-throughput and automated platform for development of manufacturing cell lines for the production of protein therapeutics.
The combination of BD FACS Aria Cell Sorter, CloneSelect Imager and TECAN Freedom EVO liquid handling system has enabled a high-throughput and more efficient cell line development process. In this operation, production host cells are first transfected with an expression vector carrying the gene of interest 1, followed by the treatment with a selection agent. The stably-transfected cells are then stained with fluorescence-labeled anti-human IgG antibody, and are subsequently subject to flow cytometry analysis 2-4. Highly productive cells are selected based on fluorescence intensity and are isolated by single-cell sorting on a BD FACSAria. Colony formation from single-cell stage was detected microscopically and a series of time-laps digital images are taken by CloneSelect Imager for the documentation of cell line history. After single clones have formed, these clones were screened for productivity by ELISA performed on a TECAN Freedom EVO liquid handling system. Approximately 2,000 - 10,000 clones can be screened per operation cycle with the current system setup.
This integrated approach has been used to generate high producing Chinese hamster ovary (CHO) cell lines for the production of therapeutic monoclonal antibody (mAb) as well as their fusion proteins. With the aid of different types of detecting probes, the method can be used for developing other protein therapeutics or be applied to other production host systems. Comparing to the traditional manual procedure, this automated platform demonstrated advantages of significantly increased capacity, ensured clonality, traceability in cell line history with electronic documentation and much reduced opportunity in operator error.

A high-throughput, automated platform of manufacturing cell line development for producing protein therapeutics is described. Implementation of BD FACS Aria Cell Sorter, CloneSelect Imager and TECAN Freedom EVO liquid handling system has demonstrated significantly increased processing capacity in cell line development with improved cell line quality and high reproducibility.

The fast-growing biopharmaceutical industry demands speedy development of highly efficient and reliable production systems to meet the increasing ...

Stem Cell Transplantation Strategies for the Restoration of Cognitive Dysfunction Caused by Cranial Radiotherapy

Radiotherapy often provides the only clinical recourse for those afflicted with primary or metastatic brain tumors. While beneficial, cranial irradiation can induce a progressive and debilitating decline in cognition that may, in part, be caused by the depletion of neural stem cells. Given the increased survival of patients diagnosed with brain cancer, quality of life in terms of cognitive health has become an increasing concern, especially in the absence of any satisfactory long-term treatments.
To address this serious health concern we have used stem cell replacement as a strategy to combat radiation-induced cognitive decline. Our model utilizes athymic nude rats subjected to cranial irradiation. The ionizing radiation is delivered as either whole brain or as a highly focused beam to the hippocampus via linear accelerator (LINAC) based stereotaxic radiosurgery. Two days following irradiation, human neural stem cells (hNSCs) were stereotaxically transplanted into the hippocampus. Rats were then assessed for changes in cognition, grafted cell survival and for the expression of differentiation-specific markers 1 and 4-months after irradiation. Our cognitive testing paradigms have demonstrated that animals engrafted with hNSCs exhibit significant improvements in cognitive function. Unbiased stereology reveals significant survival (10-40%) of the engrafted cells at 1 and 4-months after transplantation, dependent on the amount and type of cells grafted. Engrafted cells migrate extensively, differentiate along glial and neuronal lineages, and express a range of immature and mature phenotypic markers.
Our data demonstrate direct cognitive benefits derived from engrafted human stem cells, suggesting that this procedure may one day afford a promising strategy for the long-term functional restoration of cognition in individuals subjected to cranial radiotherapy. To promote the dissemination of the critical procedures necessary to replicate and extend our studies, we have provided written and visual documentation of several key steps in our experimental plan, with an emphasis on stereotaxic radiosurgey and transplantation.

Brain tumor patients routinely undergo cranial radiotherapy, and while beneficial, this treatment often results in debilitating cognitive dysfunction. This serious unresolved problem has at present, no clinical recourse, and has driven our efforts to devise stem cell based therapies for the recovery of radiation-induced cognitive decrements.

Radiotherapy often provides the only clinical recourse for those afflicted with primary or metastatic brain tumors. While beneficial, cranial irradiation ...

Mouse Eye Enucleation for Remote High-throughput Phenotyping

The mouse eye is an important genetic model for the translational study of human ophthalmic disease. Blinding diseases in humans, such as macular degeneration, photoreceptor degeneration, cataract, glaucoma, retinoblastoma, and diabetic retinopathy have been recapitulated in transgenic mice.1-5 Most transgenic and knockout mice have been generated by laboratories to study non-ophthalmic diseases, but genetic conservation between organ systems suggests that many of the same genes may also play a role in ocular development and disease. Hence, these mice represent an important resource for discovering new genotype-phenotype correlations in the eye. Because these mice are scattered across the globe, it is difficult to acquire, maintain, and phenotype them in an efficient, cost-effective manner. Thus, most high-throughput ophthalmic phenotyping screens are restricted to a few locations that require on-site, ophthalmic expertise to examine eyes in live mice. 6-9 An alternative approach developed by our laboratory is a method for remote tissue-acquisition that can be used in large or small-scale surveys of transgenic mouse eyes. Standardized procedures for video-based surgical skill transfer, tissue fixation, and shipping allow any lab to collect whole eyes from mutant animals and send them for molecular and morphological phenotyping. In this video article, we present techniques to enucleate and transfer both unfixed and perfusion fixed mouse eyes for remote phenotyping analyses.

The dissection technique illustrates enucleation of the mouse eye for tissue fixation to perform phenotyping in high-throughput screens.

The mouse eye is an important genetic model for the translational study of human ophthalmic disease. Blinding diseases in humans, such as macular ...

High Throughput Sequential ELISA for Validation of Biomarkers of Acute Graft-Versus-Host Disease

Unbiased discovery proteomics strategies have the potential to identify large numbers of novel biomarkers that can improve diagnostic and prognostic testing in a clinical setting and may help guide therapeutic interventions. When large numbers of candidate proteins are identified, it may be difficult to validate candidate biomarkers in a timely and efficient fashion from patient plasma samples that are event-driven, of finite volume and irreplaceable, such as at the onset of acute graft-versus-host disease (GVHD), a potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation (HSCT).
Here we describe the process of performing commercially available ELISAs for six validated GVHD proteins: IL-2R&alpha;5, TNFR16, HGF7, IL-88, elafin2, and REG3&alpha;3 (also known as PAP1) in a sequential fashion to minimize freeze-thaw cycles, thawed plasma time and plasma usage. For this procedure we perform the ELISAs in sequential order as determined by sample dilution factor as established in our laboratory using manufacturer ELISA kits and protocols with minor adjustments to facilitate optimal sequential ELISA performance. The resulting plasma biomarker concentrations can then be compiled and analyzed for significant findings within a patient cohort. While these biomarkers are currently for research purposes only, their incorporation into clinical care is currently being investigated in clinical trials.
This technique can be applied to perform ELISAs for multiple proteins/cytokines of interest on the same sample(s) provided the samples do not need to be mixed with other reagents. If ELISA kits do not come with pre-coated plates, 96-well half-well plates or 384-well plates can be used to further minimize use of samples/reagents.

High throughput validation of multiple candidate biomarkers can be performed by sequential ELISA in order to minimize freeze/thaw cycles and use of precious plasma samples. Here, we demonstrate how to sequentially perform ELISAs for six different validated plasma biomarkers1-3 of graft-versus-host disease (GVHD)4 on the same plasma sample.

Unbiased discovery proteomics strategies have  the potential to identify large numbers of novel biomarkers that can improve  diagnostic and prognostic ...

Isolation, Characterization and Comparative Differentiation of Human Dental Pulp Stem Cells Derived from Permanent Teeth by Using Two Different Methods

Developing wisdom teeth are easy-accessible source of stem cells during the adulthood which could be obtained by routine orthodontic treatments. Human pulp-derived stem cells (hDPSCs) possess high proliferation potential with multi-lineage differentiation capacity compare to the ordinary source of adult stem cells1-8; therefore, hDPSCs could be the good candidates for autologous transplantation in tissue engineering and regenerative medicine. Along with these benefits, possessing the mesenchymal stem cells (MSC) features, such as immunolodulatory effect, make hDPSCs more valuable, even in the case of allograft transplantation6,9,10. Therefore, the primary step for using this source of stem cells is to select the best protocol for isolating hDPSCs from pulp tissue. In order to achieve this goal, it is crucial to investigate the effect of various isolation conditions on different cellular behaviors, such as their common surface markers &amp; also their differentiation capacity.
Thus, here we separate human pulp tissue from impacted third molar teeth, and then used both existing protocols based on literature, for isolating hDPSCs,11-13 i.e. enzymatic dissociation of pulp tissue (DPSC-ED) or outgrowth from tissue explants (DPSC-OG). In this regards, we tried to facilitate the isolation methods by using dental diamond disk. Then, these cells characterized in terms of stromal-associated Markers (CD73, CD90, CD105 &amp; CD44), hematopoietic/endothelial Markers (CD34, CD45 &amp; CD11b), perivascular marker, like CD146 and also STRO-1. Afterwards, these two protocols were compared based on the differentiation potency into odontoblasts by both quantitative polymerase chain reaction (QPCR) &amp; Alizarin Red Staining. QPCR were used for the assessment of the expression of the mineralization-related genes (alkaline phosphatase; ALP, matrix extracellular phosphoglycoprotein; MEPE &amp; dentin sialophosphoprotein; DSPP).14

The method described isolation and characterization of human Dental Pulp Stem Cells (hDPSCs) by using either enzymatic dissociation of pulp (DPSC-ED) or direct outgrowth of stem cells from pulp tissue explants (DPSC-OG). Then followed by in vitro comparative differentiation of both types of hDPSCs into odontoblasts.

Developing wisdom teeth are easy-accessible source of stem cells during the adulthood which could be obtained by routine orthodontic treatments. Human ...

Time-lapse Imaging of Primary Preneoplastic Mammary Epithelial Cells Derived from Genetically Engineered Mouse Models of Breast Cancer

Time-lapse imaging can be used to compare behavior of cultured primary preneoplastic mammary epithelial cells derived from different genetically engineered mouse models of breast cancer. For example, time between cell divisions (cell lifetimes), apoptotic cell numbers, evolution of morphological changes, and mechanism of colony formation can be quantified and compared in cells carrying specific genetic lesions. Primary mammary epithelial cell cultures are generated from mammary glands without palpable tumor. Glands are carefully resected with clear separation from adjacent muscle, lymph nodes are removed, and single-cell suspensions of enriched mammary epithelial cells are generated by mincing mammary tissue followed by enzymatic dissociation and filtration. Single-cell suspensions are plated and placed directly under a microscope within an incubator chamber for live-cell imaging. Sixteen 650 &mu;m x 700 &mu;m fields in a 4x4 configuration from each well of a 6-well plate are imaged every 15 min for 5 days. Time-lapse images are examined directly to measure cellular behaviors that can include mechanism and frequency of cell colony formation within the first 24 hr of plating the cells (aggregation versus cell proliferation), incidence of apoptosis, and phasing of morphological changes. Single-cell tracking is used to generate cell fate maps for measurement of individual cell lifetimes and investigation of cell division patterns. Quantitative data are statistically analyzed to assess for significant differences in behavior correlated with specific genetic lesions.

Time-lapse imaging is used to assess behavior of primary preneoplastic mammary epithelial cells derived from genetically engineered mouse models of breast cancer risk to determine if there are correlations between specific behavioral parameters and distinct genetic lesions.

Time-lapse  imaging can be used to compare behavior of cultured primary preneoplastic  mammary epithelial cells derived from different genetically ...

Sequential In vivo Imaging of Osteogenic Stem/Progenitor Cells During Fracture Repair

Bone turns over continuously and is highly regenerative following injury. Osteogenic stem/progenitor cells have long been hypothesized to exist, but in vivo demonstration of such cells has only recently been attained. Here, in vivo imaging techniques to investigate the role of endogenous osteogenic stem/progenitor cells (OSPCs) and their progeny in bone repair are provided. Using osteo-lineage cell tracing models and intravital imaging of induced microfractures in calvarial bone, OSPCs can be directly observed during the first few days after injury, in which critical events in the early repair process occur. Injury sites can be sequentially imaged revealing that OSPCs relocate to the injury, increase in number and differentiate into bone forming osteoblasts. These methods offer a means of investigating the role of stem cell-intrinsic and extrinsic molecular regulators for bone regeneration and repair.

Sequential In vivo Imaging of Osteogenic Stem/Progenitor Cells During Fracture Repair

Quantitative measurement of bone progenitor function in fracture healing requires high resolution serial imaging technology. Here, protocols are provided for using intravital microscopy and osteo-lineage tracking to sequentially image and quantify the migration, proliferation and differentiation of endogenous osteogenic stem/progenitor cells in the process of repairing bone fracture.

Bone turns over continuously and is highly regenerative following injury. Osteogenic stem/progenitor cells have long been hypothesized to exist, but in ...

Studying Pancreatic Cancer Stem Cell Characteristics for Developing New Treatment Strategies

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor initiation, metastasis and resistance to radio- and chemotherapy. Here we describe a specific methodology for culturing primary human pancreatic CSCs as tumor spheres in anchorage-independent conditions. Cells are grown in serum-free, non-adherent conditions in order to enrich for CSCs while their more differentiated progenies do not survive and proliferate during the initial phase following seeding of single cells. This assay can be used to estimate the percentage of CSCs present in a population of tumor cells. Both size (which can range from 35 to 250 micrometers) and number of tumor spheres formed represents CSC activity harbored in either bulk populations of cultured cancer cells or freshly harvested and digested tumors 1,2. Using this assay, we recently found that metformin selectively ablates pancreatic CSCs; a finding that was subsequently further corroborated by demonstrating diminished expression of pluripotency-associated genes/surface markers and reduced in vivo tumorigenicity of metformin-treated cells. As the final step for preclinical development we treated mice bearing established tumors with metformin and found significantly prolonged survival. Clinical studies testing the use of metformin in patients with PDAC are currently underway (e.g., NCT01210911, NCT01167738, and NCT01488552). Mechanistically, we found that metformin induces a fatal energy crisis in CSCs by enhancing reactive oxygen species (ROS) production and reducing mitochondrial transmembrane potential. In contrast, non-CSCs were not eliminated by metformin treatment, but rather underwent reversible cell cycle arrest. Therefore, our study serves as a successful example for the potential of in vitro sphere formation as a screening tool to identify compounds that potentially target CSCs, but this technique will require further in vitro and in vivo validation to eliminate false discoveries.

Pancreatic cancer stem cells (CSCs) can be expanded in vitro using the anchorage-independent sphere culture technique, which represents a powerful tool to study CSC biology and can serve as the first step to develop novel CSC-targeting therapies. Here the methodology for expanding, analyzing and targeting of pancreatic CSCs is provided.

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor ...

An Organotypic High Throughput System for Characterization of Drug Sensitivity of Primary Multiple Myeloma Cells

In this work we describe a novel approach that combines ex vivo drug sensitivity assays and digital image analysis to estimate chemosensitivity and heterogeneity of patient-derived multiple myeloma (MM) cells. This approach consists in seeding primary MM cells freshly extracted from bone marrow aspirates into microfluidic chambers implemented in multi-well plates, each consisting of a reconstruction of the bone marrow microenvironment, including extracellular matrix (collagen or basement membrane matrix) and stroma (patient-derived mesenchymal stem cells) or human-derived endothelial cells (HUVECs). The chambers are drugged with different agents and concentrations, and are imaged sequentially for 96 hr through bright field microscopy, in a motorized microscope equipped with a digital camera. Digital image analysis software detects live and dead cells from presence or absence of membrane motion, and generates curves of change in viability as a function of drug concentration and exposure time. We use a computational model to determine the parameters of chemosensitivity of the tumor population to each drug, as well as the number of sub-populations present as a measure of tumor heterogeneity. These patient-tailored models can then be used to simulate therapeutic regimens and estimate clinical response.

We describe a high-throughput drug sensitivity assay for primary multiple myeloma cells. It consists of a reconstruction of the bone marrow microenvironment (including extracellular matrix and stroma) in multi-well plates, and a non-invasive method for longitudinal quantification of cell viability.

In this work we describe a novel approach that combines ex vivo drug sensitivity assays and digital image analysis to estimate chemosensitivity and ...

Preparation and In Vitro Characterization of Magnetized miR-modified Endothelial Cells

To date, the available surgical and pharmacological treatments for cardiovascular diseases (CVD) are limited and often palliative. At the same time, gene and cell therapies are highly promising alternative approaches for CVD treatment. However, the broad clinical application of gene therapy is greatly limited by the lack of suitable gene delivery systems. The development of appropriate gene delivery vectors can provide a solution to current challenges in cell therapy. In particular, existing drawbacks, such as limited efficiency and low cell retention in the injured organ, could be overcome by appropriate cell engineering (i.e., genetic) prior to transplantation. The presented protocol describes the efficient and safe transient modification of endothelial cells using a polyethyleneimine superparamagnetic magnetic nanoparticle (PEI/MNP)-based delivery vector. Also, the algorithm and methods for cell characterization are defined. The successful intracellular delivery of microRNA (miR) into human umbilical vein endothelial cells (HUVECs) has been achieved without affecting cell viability, functionality, or intercellular communication. Moreover, this approach was proven to cause a strong functional effect in introduced exogenous miR. Importantly, the application of this MNP-based vector ensures cell magnetization, with accompanying possibilities of magnetic targeting and non-invasive MRI tracing. This may provide a basis for magnetically guided, genetically engineered cell therapeutics that can be monitored non-invasively with MRI.

Preparation and In Vitro Characterization of Magnetized miR-modified Endothelial Cells

This manuscript describes the efficient, non-viral delivery of miR to endothelial cells by a PEI/MNP vector and their magnetization. Thus, in addition to genetic modification, this approach allows for magnetic cell guidance and MRI detectability. The technique can be used to improve the characteristics of therapeutic cell products.

To date, the available surgical and pharmacological treatments for cardiovascular diseases (CVD) are limited and often palliative. At the same time, gene ...