Name: leukodepletion filters-derived cd34+ cells as a cell source to study megakaryocyte differentiation and platelet formation
Uploaded: 2021-05-20T14:00:00
Description: Watch this Scientific Journal Video about Leukodepletion Filters-Derived CD34+ Cells As a Cell Source to Study Megakaryocyte Differentiation and Platelet Formation at JoVE.com

This work has been supported&#160;by ANR (Agence National de la Recherche) Grant ANR- 17-CE14-0001-1.

Control human samples were obtained from volonteer blood donors who gave written informed consent recruited by the blood transfusion center where the research was performed (Etablissement Fran&#231;ais du Sang-Grand Est). All procedures were registered and approved by the French Ministry of Higher Education and Research and registered under the number AC_2015_2371.The donors gave their approval in the CODHECO number AC- 2008 - 562 consent form, in order for the samples to be used for research purposes. Human studies were...

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This protocol describes a method for producing MK capable of emitting proplatelets from blood-derived HP and to release platelets from the culture medium. HP are obtained from LRF, a by-product of the blood banks, used to remove contaminating leukocytes from cellular blood products and avoid adverse reactions. Although this method is relatively simple, a few points deserve special attention.
Deposition of the cell suspension on the density gradient medium (step 1.3.1) has to be performed gentl...

Blood platelets come from specialized large polyploid cells, the megakaryocytes (MK), that originate from a constant and fine-tuned production process known as megakaryopoiesis (MKP). At the apex of this process are hematopoietic stem cells which, in contact with the bone marrow environment (cytokines, transcription factors, hematopoietic niche), will be able to proliferate and differentiate into hematopoietic progenitors (HP) able to commit toward the megakaryocytic pathway, giving rise to immature MKs1. Under the influence of various cytokines, and in particular thrombopoietin (TPO), which is the major cytokine of MKP; the MK will then undergo two major stages of maturation: endomitosis and the development of demarcation membranes (DMS). This fully mature MK then appears close to a sinusoid vessel in which it can emit cytoplasmic extensions, the proplatelets, which will be released under the blood flow and subsequently remodeled into functional platelets2. The cloning of TPO in 19943 provided a boost in the study of MKP by accelerating the development of in vitro culture techniques allowing HP differentiation and MK maturation.
There are many pathologies affecting blood platelets, both in terms of platelet number (increase or decrease) and function4,5. Being able to recapitulate MKP in vitro from human HP could improve understanding of the molecular and cellular mechanisms underlying this process and ultimately the therapeutic management of patients.
Various sources of human HP are suitable: cord blood, bone marrow, and peripheral blood6,7,8. Harvesting HP from peripheral blood raises less logistical and ethical problems than their recovery from cord blood or the bone marrow. HP can be recovered from leukapheresis or buffy coat, but these sources are expensive and not always available in blood centers. Other protocols, less expensive and easier to perform, allow direct recovery of human peripheral blood mononuclear cells (PBMCs) without the need for prior CD34 driven isolation4,8. However, the purity of megakaryocytes is not satisfactory with this method and a selection of CD34+ cells from PBMC is recommended for optimal differentiation into MK. This led us to implement a HP purification from leukoreduction filters (LRF), routinely used in blood banks to remove white blood cells and thus avoid adverse immunological reactions9. Indeed, since 1998, platelet concentrates have been automatically leukodepleted in France. At the end of this process, LRF are discarded and all the cells retained in the LRF are destroyed. Cells in LRFs are, therefore, readily available at no additional cost. LRFs have a cellular content close to that obtained by leukapheresis or in buffy coats, notably in their composition of CD34+ HP making them a remarkably attractive source10. LRF as a human HP source has already been demonstrated to provide cells with intact functional capacities11. This source has the advantage of being abundant and affordable for laboratory research. In this context, this article describes successively: i) the extraction and selection of CD34+ HP from LRFs; ii) a two-phase optimized culture, which recapitulates the commitment of HP into the megakaryocytic pathway and the maturation of MK capable of emitting proplatelets; iii) a method for efficiently releasing platelets from these MK; and iv) a procedure for phenotyping MK and cultured platelets.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr >
			<td >7-AAD</td>
			<td >Biolegend</td>
			<td >558819</td>
			<td ></td>
		</tr>
		<tr >
			<td >ACD</td>
			<td>EFS-Alsace</td>
			<td >NA</td>
			<td></td>
		</tr>
		<tr >
			<td >Anti-CD34-PE&#160;</td>
			<td>Miltenyi biotec</td>
			<td>130-081-002</td>
			<td></td>
		</tr>
		<tr >
			<td >Anti-CD34-PECy7</td>
			<td >eBioscience</td>
			<td >25-0349-42</td>
			<td></td>
		</tr>
		<tr >
			<td >Anti-CD41-Alexa Fluor 488</td>
			<td >Biolegend</td>
			<td >303724</td>
			<td></td>
		</tr>
		<tr >
			<td >Anti-CD42a-PE</td>
			<td >BD Bioscience</td>
			<td >559919</td>
			<td></td>
		</tr>
		<tr >
			<td >Apyrase</td>
			<td >EFS-Alsace</td>
			<td >NA</td>
			<td></td>
		</tr>
		<tr >
			<td >BD Trucount Tubes</td>
			<td >BD Bioscience</td>
			<td>340334</td>
			<td></td>
		</tr>
		<tr >
			<td >CD34 MicroBead Kit UltraPure, human&#160;</td>
			<td>Miltenyi biotec</td>
			<td>130-100-453</td>
			<td></td>
		</tr>
		<tr >
			<td >Centrifuge</td>
			<td>Heraeus</td>
			<td>Megafuge 1.OR</td>
			<td>Or equivalent material</td>
		</tr>
		<tr >
			<td >Compteur ADAM&#160;</td>
			<td>DiagitalBio</td>
			<td >NA</td>
			<td>Or equivalent material</td>
		</tr>
		<tr >
			<td >Cryotubes</td>
			<td>Dutscher</td>
			<td>55002</td>
			<td>Or equivalent material</td>
		</tr>
		<tr >
			<td >Dextran from leuconostoc spp&#160;</td>
			<td>Sigma</td>
			<td>31392-50g</td>
			<td>Or equivalent material</td>
		</tr>
		<tr >
			<td >DMSO Hybri-max&#160;</td>
			<td>Sigma</td>
			<td>D2650</td>
			<td></td>
		</tr>
		<tr >
			<td >EDTA 0.5 M&#160;</td>
			<td>Gibco</td>
			<td>15575-039</td>
			<td></td>
		</tr>
		<tr >
			<td >Eppendorf 1,5 mL&#160;</td>
			<td>Dutscher</td>
			<td>616201</td>
			<td>Or equivalent material</td>
		</tr>
		<tr >
			<td >Filtration unit Steriflip PVDF</td>
			<td>Merck Millipore Ltd</td>
			<td>SE1M179M6</td>
			<td></td>
		</tr>
		<tr >
			<td >Flow Cytometer</td>
			<td >BD Bioscience</td>
			<td >Fortessa</td>
			<td></td>
		</tr>
		<tr >
			<td >Human LDL</td>
			<td>Stemcell technologies</td>
			<td>#02698</td>
			<td></td>
		</tr>
		<tr >
			<td >ILOMEDINE 0,1 mg/1 mL</td>
			<td >Bayer</td>
			<td>MA038EX</td>
			<td></td>
		</tr>
		<tr >
			<td >Inserts</td>
			<td>Fenwal</td>
			<td>R4R1401</td>
			<td>Or equivalent material</td>
		</tr>
		<tr >
			<td >Laminar flow hood&#160;</td>
			<td>Holten</td>
			<td >NA</td>
			<td>Archived product</td>
		</tr>
		<tr >
			<td >LS Columms&#160;</td>
			<td>Miltenyi Biotec</td>
			<td>130-042-401&#160;</td>
			<td></td>
		</tr>
		<tr >
			<td >Lymphoprep</td>
			<td>Stemcell</td>
			<td>7861</td>
			<td></td>
		</tr>
		<tr >
			<td >Pen Strep Glutamine (100x)</td>
			<td>Gibco</td>
			<td>10378-016</td>
			<td></td>
		</tr>
		<tr >
			<td >PBS (-)</td>
			<td>Life Technologies</td>
			<td>14190-169&#160;</td>
			<td>Or equivalent material</td>
		</tr>
		<tr >
			<td >PGi2</td>
			<td >Sigma</td>
			<td >P6188</td>
			<td></td>
		</tr>
		<tr >
			<td >Poches de transferts 600ml&#160;</td>
			<td>Macopharma</td>
			<td>VSE4001XA</td>
			<td></td>
		</tr>
		<tr >
			<td >Pre-Separation Filters (30&#181;m)</td>
			<td>Miltenyi Biotec</td>
			<td>130-041-407</td>
			<td></td>
		</tr>
		<tr >
			<td >StemRegenin 1 (SR1)</td>
			<td>Stemcell technologies</td>
			<td>#72344</td>
			<td></td>
		</tr>
		<tr >
			<td >StemSpan Expansion Supplement (100x)</td>
			<td>Stemcell technologies</td>
			<td>#02696</td>
			<td></td>
		</tr>
		<tr >
			<td >StemSpan-SFEM&#160;</td>
			<td>Stemcell technologies</td>
			<td>#09650</td>
			<td></td>
		</tr>
		<tr >
			<td >Stericup Durapore 0,22&#181;m PVDF</td>
			<td>Merck Millipore Ltd</td>
			<td>SCGVU05RE</td>
			<td></td>
		</tr>
		<tr >
			<td >SVF Hyclone&#160;</td>
			<td>Thermos scientific</td>
			<td>SH3007103</td>
			<td></td>
		</tr>
		<tr >
			<td >Syringues 30 mL&#160;</td>
			<td>Terumo</td>
			<td>SS*30ESE1</td>
			<td>Or equivalent material</td>
		</tr>
		<tr >
			<td >Syringe filters Millex 0,22&#181;M PVDF</td>
			<td>Merck Millipore Ltd</td>
			<td>SLGV033RB</td>
			<td></td>
		</tr>
		<tr >
			<td >TPO</td>
			<td>Stemcell technologies</td>
			<td>#02822</td>
			<td></td>
		</tr>
		<tr >
			<td >Tubes 50 mL</td>
			<td>Sarstedt</td>
			<td>62.548.004 PP</td>
			<td>Or equivalent material</td>
		</tr>
		<tr >
			<td >Tubes 15 mL&#160;</td>
			<td>Sarstedt</td>
			<td>62.554.001 PP</td>
			<td>Or equivalent material</td>
		</tr>
		<tr >
			<td >Tubulures</td>
			<td>B Braun</td>
			<td>4055137</td>
			<td>Or equivalent material</td>
		</tr>
	</tbody>
</table>

leukodepletion filters-derived cd34+ cells as a cell source to study megakaryocyte differentiation and platelet formation

The in vitro expansion and differentiation of human hematopoietic progenitors into megakaryocytes capable of elongating proplatelets and releasing platelets allows an in-depth study of the mechanisms underlying platelet biogenesis. Available culture protocols are mostly based on hematopoietic progenitors derived from bone marrow or cord blood raising a number of ethical, technical, and economic concerns. If there are already available protocols for obtaining CD34 cells from peripheral blood, this manuscript proposes a straightforward and optimized protocol for obtaining CD34+ cells from leukodepletion filters readily available in blood centers. These cells are isolated from leukodepletion filters used in the preparation of blood transfusion products, corresponding to eight blood donations. These filters are meant to be discarded. A detailed procedure to collect hematopoietic progenitors identified as CD34+ cells from these filters is described. The method to obtain mature megakaryocytes extending proplatelets while discussing their phenotypic evolution is also detailed. Finally, the protocol present a calibrated pipetting method, to efficiently release platelets that are morphologically and functionally similar to native ones. This protocol can serve as a basis for evaluating pharmacological compounds acting at various steps of the process to dissect the underlying mechanisms and approach the in vivo platelet yields.

Extraction and selection of CD34+ cells from LRFs 
Here, the method, derived from Peytour et al.9, describes the extraction and selection of CD34+ cells from discarded LRFs available in blood banks after leukocyte removal. Following the backflush procedure, usually 1.03 x 109 &#177;&#160;2.45 x 108 cells/LRF (Mean&#177;SEM; n = 155) are recovered with a viability of 94.88 &#177; 0.10% (Figure 2A i...

Watch this Scientific Journal Video about Leukodepletion Filters-Derived CD34+ Cells As a Cell Source to Study Megakaryocyte Differentiation and Platelet Formation at JoVE.com

Leukodepletion Filters-Derived CD34+ Cells As a Cell Source to Study Megakaryocyte Differentiation and Platelet Formation

This protocol describes in detail all the steps involved in obtaining leukofilter-derived CD34+ hematopoietic progenitors and their in vitro differentiation and maturation into proplatelet-bearing megakaryocytes that are able to release platelets in the culture medium. This procedure is useful for in-depth analysis of cellular and molecular mechanisms controlling megakaryopoiesis.

The in vitro expansion and differentiation of human hematopoietic progenitors into megakaryocytes capable of elongating proplatelets and releasing ...

This protocol proposes a simple method for obtaining human hematopoietic progenitors, and for inducing their differentiation into megakaryocytes. It can serve as a basis for better understanding of megakaryopoiesis This technique uses a source, but offers the advantage of being affordable and abundant for laboratory research in hematopoiesis. This method is used to better understand megakaryopoiesis for the cell to be used in therapy they will need to be prepared in the GMP conditions, which is currently not the case.Understanding the steps including PBMC collection can only be fully complete with a visual demonstration. Before beginning an experiment, connect a leukoreduction filter to an empty 600 milliliter transfer bag and to a tubing set. In a bio safety cabinet inject 25 milliliters of filtered elution buffer per leukoreduction filter into the empty bag, and use a 30 milliliter syringe to gently aspirate the bag contents through the filter.Transfer the collected red blood cells into a new 50 milliliter tube, and dilute the cell suspension by half with 2%dextran. Mix well to aggregate the blood cells and allow the cells to sediment for 30 minutes at room temperature. When the red blood cells have settled transfer the supernatant to a 50 milliliter tube and fill the tube with two millimolar PBS EDTA solution.Gently overlay half of the supernatant onto 25 milliliters of density gradient medium in each of two 50 milliliter tubes without disturbing the gradient surface and separate the cells by density gradient centrifugation. Use a disposable pipette to transfer the cells from each interface to a new 50 milliliter tube. Wash the cells two times in 50 milliliters of two millimolar PBS EDTA per wash.After the second wash, resuspend the pellets in a single 50 milliliter volume of fresh PBS EDTA for counting. Here is possible to stop the procedure by maintaining the collected cells under agitation at four degrees Celsius during the night. For CD34+cell selection, determine the cell number and collect the cells by centrifugation and resuspend the cell pellet in 300 microliters of two millimolar PBS EDTA per 10 to the eighth cells.Add the appropriate volume of FC receptor blocking reagent and 50 microliters of CD34 micro-beads per 10 to the eighth cells. After 30 minutes at four degrees Celsius, wash the cells with two millimolar PBS EDTA, and resuspend the pellet in 500 microliters of fresh two millimolar PBS EDTA, per 10 to the eight cells. Humidify and appropriately size magnetic column with PBS EDTA, and then add the sample to the column.Wash the column two times with three milliliters of two millimolar PBS EDTA per wash. Before eluding the CD34+cells, with two five milliliter volumes of two millimolar PBS EDTA per elution. To assess the purity of the magnetic bead selected cells, add two microliters of an appropriate human anti CD34 antibody to a 100 microliter aliquot of the isolated cells and mix well before incubating for 15 minutes at four degrees celsius.Following incubation, wash the cells in PBS and resuspend the pellet in 200 microliters of PBS for analysis of the purity of the cell sample by flow cytometry. After counting, collect the CD34+cells by centrifugation and immediately resuspend the pellet in cold solution one to a density of 10 to the six cells per milliliter before quickly adding the cell suspension to cold solution two. Then immediately place the cryo tube in a minus 80 degree Celsius freezer for 24 hours before transferring the cryo tube to liquid nitrogen storage.In this representative study, the cells were recovered by leukoreduction filtration as demonstrated with an approximate 95%viability. After magnetic bead selection, a greater than 90%pure CD34+cell population was obtained. Cell proliferation typically decreases after a week of culture, but with no significant changes in cell viability.By day seven, the CD34+cells should begin expressing CD41, a specific and early marker or for megakaryocyte and platelet development. By day 10, the majority of the cells in the culture typically develop into mature CD41 expressing megakaryocytes. By day 13, megakaryocyte pro platelet extension and platelet release can be observed by light microscopy.The total number of CD41, CD42, 8 positive platelets released into the culture can then be quantified using a calibrated number of fluorescent beads. This method paves the way for enhancing the underlying mechanisms of megakaryopoiesis and for increasing platelets yields in visual. Even if this method seems tedious, it is very simple you just need to be patient and prepare all the regions in advance.Although our critical concerns megakaryopoiesis we obtain CD42 cells can be used in over hematopoietic pathways.

leukodepletion-filters-derived-cd34-cells-as-cell-source-to-study

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Biology

Testing Visual Sensitivity to the Speed and Direction of Motion in Lizards

Testing visual sensitivity in any species provides basic information regarding behaviour, evolution, and ecology. However, testing specific features of the visual system provide more empirical evidence for functional applications. Investigation into the sensory system provides information about the sensory capacity, learning and memory ability, and establishes known baseline behaviour in which to gauge deviations (Burghardt, 1977). However, unlike mammalian or avian systems, testing for learning and memory in a reptile species is difficult. Furthermore, using an operant paradigm as a psychophysical measure of sensory ability is likewise as difficult. Historically, reptilian species have responded poorly to conditioning trials because of issues related to motivation, physiology, metabolism, and basic biological characteristics. Here, I demonstrate an operant paradigm used a novel model lizard species, the Jacky dragon (Amphibolurus muricatus) and describe how to test peripheral sensitivity to salient speed and motion characteristics. This method uses an innovative approach to assessing learning and sensory capacity in lizards. I employ the use of random-dot kinematograms (RDKs) to measure sensitivity to speed, and manipulate the level of signal strength by changing the proportion of dots moving in a coherent direction. RDKs do not represent a biologically meaningful stimulus, engages the visual system, and is a classic psychophysical tool used to measure sensitivity in humans and other animals. Here, RDKs are displayed to lizards using three video playback systems. Lizards are to select the direction (left or right) in which they perceive dots to be moving. Selection of the appropriate direction is reinforced by biologically important prey stimuli, simulated by computer-animated invertebrates.

Testing visual sensitivity in lizards using an operant conditioning paradigm that employs video playback of random-dot kinematograms and computer-generated invertebrates.

Testing visual sensitivity in any species provides basic information regarding behaviour, evolution, and ecology. However, testing specific features of ...

Preparation of Pooled Human Platelet Lysate (pHPL) as an Efficient Supplement for Animal Serum-Free Human Stem Cell Cultures

Platelet derived growth factors have been shown to stimulate cell proliferation efficiently in vivo1,2 and in vitro. This effect has been reported for mesenchymal stromal cells (MSCs), fibroblasts and endothelial colony-forming cells with platelets activated by thrombin3-5 or lysed by freeze/thaw cycles6-14 before the platelet releasate is added to the cell culture medium. The trophic effect of platelet derived growth factors has already been tested in several trials for tissue engineering and regenerative therapy.1,15-17 Varying efficiency is considered to be at least in part due to individually divergent concentrations of growth factors18,19 and a current lack of standardized protocols for platelet preparation.15,16 This protocol presents a practicable procedure to generate a pool of human platelet lysate (pHPL) derived from routinely produced platelet rich plasma (PRP) of forty to fifty single blood donations. By several freeze/thaw cycles the platelet membranes are damaged and growth factors are efficiently released into the plasma. Finally, the platelet fragments are removed by centrifugation to avoid extensive aggregate formation and deplete potential antigens. The implementation of pHPL into standard culture protocols represents a promising tool for further development of cell therapeutics propagated in an animal protein-free system.

Preparation of Pooled Human Platelet Lysate pHPL as an Efficient Supplement for Animal Serum-Free Human Stem Cell Cultures

Human platelet lysate is a rich source of growth factors and a potent supplement in cell culture. This protocol presents the process of preparing a large pool of human platelet lysate by starting from platelet rich plasma, performing several freeze-thaw cycles and depleting the platelet fragments.

Platelet derived growth factors have been shown to stimulate cell proliferation efficiently in vivo1,2 and in vitro. This effect has been reported for ...

Platelet Adhesion and Aggregation Under Flow using Microfluidic Flow Cells

Platelet aggregation occurs in response to vascular injury where the extracellular matrix below the endothelium has been exposed. The platelet adhesion cascade takes place in the presence of shear flow, a factor not accounted for in conventional (static) well-plate assays. This article reports on a platelet-aggregation assay utilizing a microfluidic well-plate format to emulate physiological shear flow conditions. Extracellular proteins, collagen I or von Willebrand factor are deposited within the microfluidic channel using active perfusion with a pneumatic pump. The matrix proteins are then washed with buffer and blocked to prepare the microfluidic channel for platelet interactions. Whole blood labeled with fluorescent dye is perfused through the channel at various flow rates in order to achieve platelet activation and aggregation. Inhibitors of platelet aggregation can be added prior to the flow cell experiment to generate IC50 dose response data.

The platelet adhesion cascade takes place in the presence of shear flow, a factor not accounted for in conventional (static) well-plate assays. This article reports on a platelet-aggregation assay utilizing a microfluidic well-plate format to emulate physiological shear flow conditions.

Platelet aggregation occurs in response to vascular injury where the extracellular matrix below the endothelium has been exposed. The platelet adhesion ...

Differentiation of Embryonic Stem Cells into Oligodendrocyte Precursors

Oligodendrocytes are the myelinating cells of the central nervous system. For regenerative cell therapy in demyelinating diseases, there is significant interest in deriving a pure population of lineage-committed oligodendrocyte precursor cells (OPCs) for transplantation. OPCs are characterized by the activity of the transcription factor Olig2 and surface expression of a proteoglycan NG2. Using the GFP-Olig2 (G-Olig2) mouse embryonic stem cell (mESC) reporter line, we optimized conditions for the differentiation of mESCs into GFP+Olig2+NG2+ OPCs. In our protocol, we first describe the generation of embryoid bodies (EBs) from mESCs. Second, we describe treatment of mESC-derived EBs with small molecules: (1) retinoic acid (RA) and (2) a sonic hedgehog (Shh) agonist purmorphamine (Pur) under defined culture conditions to direct EB differentiation into the oligodendroglial lineage. By this approach, OPCs can be obtained with high efficiency (&gt;80%) in a time period of 30 days. Cells derived from mESCs in this protocol are phenotypically similar to OPCs derived from primary tissue culture. The mESC-derived OPCs do not show the spiking property described for a subpopulation of brain OPCs in situ. To study this electrophysiological property, we describe the generation of spiking mESC-derived OPCs by ectopically expressing NaV1.2 subunit. The spiking and nonspiking cells obtained from this protocol will help advance functional studies on the two subpopulations of OPCs.

We describe a small molecule-based protocol for differentiation of mouse embryonic stem cells into oligodendrocyte precursor cells (OPCs). This protocol generates Olig2+NG2+ OPCs with high efficiency by 30 days of differentiation. We also describe a method to generate "spiking" OPCs that can fire action potentials.

Oligodendrocytes are the myelinating cells of the central nervous system. For regenerative cell therapy in demyelinating diseases, there is significant ...

Fate Mapping of Human Embryonic Stem Cells by Teratoma Formation

Human embryonic stem cells (hESCs) have an unlimited capacity for self-renewal, and the ability to differentiate into cells derived from all three embryonic germ layers (1). Directed differentiation of hESCs into specific cell types has generated much interest in the field of regenerative medicine (e.g., (2-5)), and methods for determining the in vivo fate of selected or manipulated hESCs are essential to this endeavor. We have adapted a highly efficient teratoma formation assay for this purpose. A small number of specifically selected hESCs is mixed with undifferentiated wild type hESCs and Phaseolus vulgaris lectin to form a cell pellet. This is grafted beneath the kidney capsule in an immunodeficient mouse. As few as 2.5 x 105 hESCs are needed to form a 16 cm3 teratoma within 8-12 weeks. The fate of the originally selected hESCs can then be determined by immunohistochemistry. This method provides a valuable tool for characterizing tissue-specific reagents for cell-based therapy.

Directed differentiation of hESCs into specific cells has generated much interest in regenerative medicine. We provide a concise, step-by-step protocol for determining the in vivo fate of selected hESCs that provides a valuable tool for characterizing tissue-specific reagents for cell-based therapy.

Human embryonic stem cells (hESCs) have an unlimited capacity for self-renewal, and the ability to differentiate into cells derived from all three ...

A Matrigel-Based Tube Formation Assay to Assess the Vasculogenic Activity of Tumor Cells

Over the past several decades, a tube formation assay using growth factor-reduced Matrigel has been typically employed to demonstrate the angiogenic activity of vascular endothelial cells in vitro1-5. However, recently growing evidence has shown that this assay is not limited to test vascular behavior for endothelial cells. Instead, it also has been used to test the ability of a number of tumor cells to develop a vascular phenotype6-8. This capability was consistent with their vasculogenic behavior identified in xenotransplanted animals, a process known as vasculogenic mimicry (VM)9. There is a multitude of evidence demonstrating that tumor cell-mediated VM plays a vital role in the tumor development, independent of endothelial cell angiogenesis6, 10-13. For example, tumor cells were found to participate in the blood perfused, vascular channel formation in tissue samples from melanoma and glioblastoma patients8, 10, 11. Here, we described this tubular network assay as a useful tool in evaluation of vasculogenic activity of tumor cells. We found that some tumor cell lines such as melanoma B16F1 cells, glioblastoma U87 cells, and breast cancer MDA-MB-435 cells are able to form vascular tubules; but some do not such as colon cancer HCT116 cells. Furthermore, this vascular phenotype is dependent on cell numbers plated on the Matrigel. Therefore, this assay may serve as powerful utility to screen the vascular potential of a variety of cell types including vascular cells, tumor cells as well as other cells.

A tube formation assay is used to evaluate vascular activity of tumor cells.

Over the past several decades, a tube formation assay using growth factor-reduced Matrigel has been typically employed to demonstrate the angiogenic ...

Isolation and Differentiation of Stromal Vascular Cells to Beige/Brite Cells

Brown adipocytes have the ability to uncouple the respiratory chain in mitochondria and dissipate chemical energy as heat. Development of UCP1-positive brown adipocytes in white adipose tissues (so called beige or brite cells) is highly induced by a variety of environmental cues such as chronic cold exposure or by PPAR&gamma; agonists, therefore, this cell type has potential as a therapeutic target for obesity treatment. Although most immortalized adipocyte lines cannot recapitulate the process of "browning" of white fat in culture, primary adipocytes isolated from stromal vascular fraction in subcutaneous white adipose tissue (WAT) provide a reliable cellular system to study the molecular control of beige/brite cell development. Here we describe a protocol for effective isolation of primary preadipocytes and for inducing differentiation to beige/brite cells in culture. The browning effect can be assessed by the expression of brown fat-selective markers such as UCP1.

Primary white preadipocytes isolated from white adipose tissues in mice can be differentiated into beige/brite cells. Presented here is a reliable cellular model system to study the molecular regulation of "browning" of white fat.

Brown adipocytes have the ability to uncouple the  respiratory chain in mitochondria and dissipate chemical energy as heat.  Development of UCP1-positive ...

Nephrotoxin Microinjection in Zebrafish to Model Acute Kidney Injury

The kidneys are susceptible to harm from exposure to chemicals they filter from the bloodstream. This can lead to organ injury associated with a rapid decline in renal function and development of the clinical syndrome known as acute kidney injury (AKI). Pharmacological agents used to treat medical circumstances ranging from bacterial infection to cancer, when administered individually or in combination with other drugs, can initiate AKI. Zebrafish are a useful animal model to study the chemical effects on renal function in vivo, as they form an embryonic kidney comprised of nephron functional units that are conserved with higher vertebrates, including humans. Further, zebrafish can be utilized to perform genetic and chemical screens, which provide opportunities to elucidate the cellular and molecular facets of AKI and develop therapeutic strategies such as the identification of nephroprotective molecules. Here, we demonstrate how microinjection into the zebrafish embryo can be utilized as a paradigm for nephrotoxin studies.

Renal injuries incurred from nephrotoxins, which include drugs ranging from antibiotics to chemotherapeutics, can result in complex disorders whose pathogenesis remains incompletely understood. This protocol demonstrates how zebrafish can be used for disease modeling of these conditions, which can be applied to the identification of renoprotective measures.

The kidneys are susceptible to harm from exposure to chemicals they filter from the bloodstream. This can lead to organ injury associated with a rapid ...

A 3D Cartographic Description of the Cell by Cryo Soft X-ray Tomography

Imaging techniques are fundamental in order to understand cell organization and machinery in biological research and the related fields. Among these techniques, cryo soft X-ray tomography (SXT) allows imaging whole cryo-preserved cells in the water window X-ray energy range (284-543 eV), in which carbon structures have intrinsically higher absorption than water, allowing the 3D reconstruction of the linear absorption coefficient of the material contained in each voxel. Quantitative structural information at the level of whole cells up to 10 &#181;m thick is then achievable this way, with high throughput and spatial resolution down to 25-30 nm half-pitch. Cryo-SXT has proven itself relevant to current biomedical research, providing 3D information on cellular infection processes (virus, bacteria, or parasites), morphological changes due to diseases (such as recessive genetic diseases) and helping us understand drug action at the cellular level, or locating specific structures in the 3D cellular environment. In addition, by taking advantage of the tunable wavelength at synchrotron facilities, spectro-microscopy or its 3D counterpart, spectro-tomography, can also be used to image and quantify specific elements in the cell, such as calcium in biomineralization processes. Cryo-SXT provides complementary information to other biological imaging techniques such as electron microscopy, X-ray fluorescence or visible light fluorescence, and is generally used as a partner method for 2D or 3D correlative imaging at cryogenic conditions in order to link function, location, and morphology.

Here, a protocol describing the sample preparation and data collection steps required in cryo soft X-ray tomography (SXT) to image the ultrastructure of whole cryo-preserved cells at a resolution of 25 nm half pitch, is presented.

Imaging techniques are fundamental in order to understand cell organization and machinery in biological research and the related fields. Among these ...

Megakaryocyte Culture in 3D Methylcellulose-Based Hydrogel to Improve Cell Maturation and Study the Impact of Stiffness and Confinement

The 3D environment leading to both confinement and mechanical constraints is increasingly recognized as an important determinant of cell behavior. 3D culture has thus been developed to better approach the in vivo situation. Megakaryocytes differentiate from hematopoietic stem and progenitor cells (HSPCs) in the bone marrow (BM). The BM is one of the softest tissues of the body, confined inside the bone. The bone being poorly extensible at the cell scale, megakaryocytes are concomitantly subjected to a weak stiffness and high confinement. This protocol presents a method for the recovery of mouse lineage negative (Lin-) HSPCs by immuno-magnetic sorting and their differentiation into mature megakaryocytes in a 3D medium composed of methylcellulose. Methylcellulose is non-reactive towards megakaryocytes and its stiffness may be adjusted to that of normal bone marrow or increased to mimic a pathological fibrotic marrow. The process to recover the megakaryocytes for further cell analyses is also detailed in the protocol. Although proplatelet extension is prevented within the 3D milieu, it is described below how to resuspend the megakaryocytes in liquid medium and to quantify their capacity to extend proplatelets. Megakaryocytes grown in 3D hydrogel have a higher capacity to form proplatelets compared to those grown in a liquid milieu. This 3D culture allows i) to differentiate progenitors towards megakaryocytes reaching a higher maturation state, ii) to recapitulate phenotypes that may be observed in vivo but go unnoticed in classical liquid cultures, and iii) to study transduction pathways induced by the mechanical cues provided by a 3D environment.

It is now acknowledged that the three-dimensional environment of cells can play an important role in their behavior, maturation and/or differentiation. This protocol describes a three-dimensional cell culture model designed to study the impact of physical containment and mechanical constraints on megakaryocytes.

The 3D environment leading to both confinement and mechanical constraints is increasingly recognized as an important determinant of cell behavior. 3D ...