The authors would like to thank Sanjiv Gambhir for the gift of the fluc/mrfp/sr39tk reporter gene. This work was funded by The Stem Cell Network (SCN) of Canada, and The Jesse's Journey Foundation.

1. Maintenance and Propagation of C2C12 Myoblasts
<ol>
	<li>Plate C2C12 myoblasts in a 75 cm2 flask and maintain cells in high glucose Dulbecco's Modified Eagle's Serum (HG-DMEM) supplemented with fetal bovine serum (FBS) to a final concentration of 10%. Do not allow cells to become confluent at any time as this will deplete the myoblastic population. Medium should be changed every other day. Note: always warm medium to 37 &deg;C in a water bath prior to use.</li>
	<li>When myoblasts become approximately 80% confluent, passage cells to a new flask. Aspirate culture medium. Wash cells with 4-5 ml Hanks Balanced Salt Solution (HBSS) to remove all traces of culture medium, which contains trypsin-inhibiting serum. Briefly rinse the cell layer with 2-3 ml 0.25% (w/v) trypsin-EDTA solution to dissociate the adherent myoblasts from the flask. Aspirate trypsin and place flask in incubator at 37 &deg;C for 5 min.</li>
	<li>During this incubation, prepare a new flask with 9 ml of HG-DMEM/10% FBS medium. After trypsinization, add 10 ml of complete medium to cells and pipette 4-5 times to ensure collection of all cells in the medium. Add 1 ml of cell suspension to the new flask and incubate in 5% CO2 at 37 &deg;C.</li>
</ol>
2. C2C12 Cell Transfection
<ol>
	<li>Once cells have reached 50% confluency, transfect according to manufacturer's instructions from Invitrogen. Briefly, combine 90 &mu;l Lipofectamine 2000 reagent with 4.5 ml OPTI-MEM medium. In another tube, combine 36 &mu;g CMV-trifusion reporter gene DNA with 4.5 ml OPTI-MEM. Flick each tube to combine and wait 5 min. Combine contents of both tubes, mix gently and incubate at room temperature for exactly thirty minutes. Note: A second flask should also be set up for untransfected cells that only receive Lipofectamine and OPTI-MEM to serve as a negative control.</li>
	<li>Remove medium from C2C12 cells and add 15.5 ml of fresh HG-DMEM/10%FBS medium. Add transfection medium to bring total volume to 20 ml.</li>
	<li>Allow cells to transfect overnight for at least 20 hr at 37 &deg;C.</li>
	<li>Next day, aspirate transfection medium and add 10 ml HG-DMEM/10%FBS.</li>
	<li>View cells under an inverted fluorescent microscope. Capture both bright field and red fluorescence images (using a TRITC filter cube; mrfp ex/em: 584/607 nm). Count the number of RFP-expressing cells viewed under fluorescence divided by total number of cells viewed under bright field for multiple fields of view to generate transfection efficiency.</li>
</ol>
3. Assessment of Cell Survivability/MTT Assay
<ol>
	<li>One day prior to transfection, plate 1x105 C2C12 cells into each well in a 24-well plate. Cells should be plated in 500 &mu;l volumes in HG-DMEM/10%FBS .</li>
	<li>Next day, transfect myoblasts overnight as previously described. Follow manufacturer's suggestions for transfection reagent volumes for a 24-well plate. Incubate a set of wells with Lipofectamine only (no DNA) as a control. View cells under fluorescence to ensure that proper transfection has occurred.</li>
	<li>Remove transfection medium and incubate myoblasts with 5 mg/ml thiazolyl blue tetrazolium bromide (MTT) in HG-DMEM/10% FBS. Add D-luciferin to eight of the transfected wells, and incubate at 37 &deg;C for four hours.</li>
	<li>Remove medium from wells. Solubilize blue formazan crystals by adding 180 &mu;l isopropanol to each well. Shake at 37 &deg;C for 15 min.</li>
	<li>Avoiding any precipitate, pipette solution into a 96-well plate and read absorbance at 575 nm.</li>
</ol>
4. Preparation of Myoblasts for Transplant
<ol>
	<li>Remove medium, wash myoblasts with HBSS, and trypsinize cells as outlined in 1.1.</li>
	<li>Re-suspend cells in 4 ml of complete medium.</li>
	<li>Using a hemocytometer, count cells to generate volumes containing 106 myoblasts. Pipette volume into sterile 1.5 ml microtubes. With a transfection efficiency of ~10%, these values indicate that 100,000 luciferase-expressing cells are detectable on the GE ExploreOptix scanner after transplant.</li>
	<li>Attain a final injection volume of 15 &mu;l, containing 106 C2C12 cells. If necessary, centrifuge microtubes at 2,000 rpm for one minute. Carefully aspirate supernatant with a pipette. Re-suspend cells in 15 &mu;l of HG-DMEM lacking FBS.</li>
</ol>
5. Cell Implantation
<ol>
	<li>Anesthetize mouse with 2% isoflurane/2%O2. Pluck hair from the dorsal hind limb area. Maintain anesthesia at 1.5%isoflurane/2%O2.</li>
	<li>Ensure C2C12 myoblasts are well suspended. With the mouse in a prone position, extend the hind limb and use an insulin syringe to inject cells directly into the lateral head of the gastrocnemius muscle at a 30 &deg; angle. Inject transfected myoblasts into the right hind limb and untransfected myoblasts into the contralateral (left) hind limb.</li>
	<li>Perform a baseline bioluminescence scan: Quickly transfer mouse to stage in the optical scanner, laying the mouse in a prone position. Hook up the anesthetic line. To ensure the mouse remains anesthetized, a second person should be present to hook up the anesthetic line while the other places the animal in the scanner.</li>
	<li>Gently extend the hind limb so the area of injection is visible. Tape hind limbs in place with a gentle adhesive such as medical tape.</li>
	<li>Close the chamber and ensure that no light can access the interior of the scanner, as this will increase the background signal detected. The scanner should be set to parameters included in your manufacturer's instructions for bioluminescence imaging. Specifically, ensure "no laser" is selected.</li>
	<li>Draw a region of interest (ROI) around the plucked area and start scan.</li>
</ol>
6. Injection of Fluc Substrate, D-luciferin, into Mdx Mouse
<ol>
	<li>While the mouse is anesthetized intraperitoneally inject 150 mg/kg of firefly luciferase substrate, D-luciferin (from a 40 mg/ml stock solution, made up according to manufacturer's instructions).</li>
	<li>Recover mouse and allow a 15 min uptake period before preparing mouse for the next scan.</li>
</ol>
7. BLI to Target Luc-expressing MPCs Following Implant into Mouse Models of DMD
<ol>
	<li>After the uptake period, anesthetize mouse again, as described in 5.1.</li>
	<li>Transfer the mouse back to the optical scanner and perform another bioluminescence scan in the same manner as the background scan.</li>
	<li>Although a 20 min uptake period should provide maximal signal intensity, a subsequent scan may be performed.</li>
	<li>Upon completion of image acquisition, sacrifice the mouse according to guidelines set by your Institutional Animal Ethics Committee and the Canadian Council on Animal Care (CCAC). Isolate hind limb muscle and place immediately in 10% formalin to fix for paraffin embedment. Perform immunohistochemistry staining for luciferase to confirm intramuscular injection of myoblasts.</li>
</ol>

<ol>
	<li>Emery, A. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+muscular+dystrophies.">The muscular dystrophies.</a> Lancet. 359, 687-695 (2002).</li><li>Blake, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Function+and+genetics+of+dystrophin+and+dystrophin-related+proteins+in+muscle.">Function and genetics of dystrophin and dystrophin-related proteins in muscle.</a> Physiol. Rev. 82, 291-329 (2002).</li><li>Goldring, K., Partridge, T., Watt, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Muscle+stem+cells.">Muscle stem cells.</a> J. Pathol. 197, 457-467 (2002).</li><li>Partridge, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cells+that+participate+in+regeneration+of+skeletal+muscle.">Cells that participate in regeneration of skeletal muscle.</a> Gene Ther. 9, 752-753 (2002).</li><li>Moss, F. P., Leblond, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Satellite+cells+as+the+source+of+nuclei+in+muscles+of+growing+rats.">Satellite cells as the source of nuclei in muscles of growing rats.</a> Anat. Rec. 170, 421-435 (1971).</li><li>Snow, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+autoradiographic+study+of+satellite+cell+differentiation+into+regenerating+myotubes+following+transplantation+of+muscles+in+young+rats.">An autoradiographic study of satellite cell differentiation into regenerating myotubes following transplantation of muscles in young rats.</a> Cell Tissue Res. 186, 535-540 (1978).</li><li>Kuang, S., Rudnicki, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+emerging+biology+of+satellite+cells+and+their+therapeutic+potential.">The emerging biology of satellite cells and their therapeutic potential.</a> Trends Mol. Med. 14 (2), 82 (2008).</li><li>Hoffman, E. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+dystrophin+in+muscle-biopsy+specimens+from+patients+with+Duchenne's+or+Becker's+muscular+dystrophy.">Characterization of dystrophin in muscle-biopsy specimens from patients with Duchenne's or Becker's muscular dystrophy.</a> N. Engl. J. Med. 318, 1363-1368 (1988).</li><li>Ray, P., Tsien, R., Gambhir, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Construction+and+validation+of+improved+triple+fusion+reporter+gene+vectors+for+molecular+imaging+of+living+subjects.">Construction and validation of improved triple fusion reporter gene vectors for molecular imaging of living subjects.</a> Cancer Res. 67 (7), 3085 (2007).</li><li>Ray, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+tri-fusion+multimodality+reporter+gene+expression+in+living+subjects.">Imaging tri-fusion multimodality reporter gene expression in living subjects.</a> Cancer Res. 64, 1323-1330 (2004).</li><li>Massoud, T. F., Gambhir, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+imaging+in+living+subjects:+seeing+fundamental+biological+processes+in+a+new+lights.">Molecular imaging in living subjects: seeing fundamental biological processes in a new lights.</a> Genes Dev. 17, 545-580 (2003).</li><li>Sicinski, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+molecular+basis+of+muscular+dystrophy+in+the+mdx+mouse:+a+point+mutation.">The molecular basis of muscular dystrophy in the mdx mouse: a point mutation.</a> Science. 244, 1578-1580 (1989).</li><li>Mattson, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Pathogenesis of neurodegenerative disorders. In: Contemporary neuroscience. X, 294 (2001).</li><li>Andersson, J. E., Bressler, B. H., Ovalle, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+regeneration+in+hind+limb+skeletal+muscle+of+the+mdx+mouse.">Functional regeneration in hind limb skeletal muscle of the mdx mouse.</a> J. Muscle Res. Cell Motil. 9, 499-515 (1988).</li></ol>

Authors have nothing to disclose.

In this study, we have described a fast and reliable molecular imaging, reporter gene approach to non-invasively target myoblasts/MPCs following transplantation. While this study demonstrates the short-term localization of transplanted MPCs via bioluminescense imaging (BLI), the manner in which cells are targeted can, in fact, be easily applied to a longitudinal assessment of cell engraftment, through the implantation of cells that stably express the reporter gene. To this end, our group has generated t...

<table border="1">
<tbody>
 <tr>
 <td>Name of reagent</td>
 <td>Company</td>
 <td>Catalogue number</td>
 <td>Comments (optional)</td>
 </tr>
 <tr>
 <td>C2C12 myoblasts</td>
 <td>ATCC</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Dulbecco's Modified Eagle's Medium</td>
 <td>Life Technologies</td>
 <td>12800-017</td>
 <td></td>
 </tr>
 <tr>
 <td>fetal bovine serum</td>
 <td>Life Technologies</td>
 <td>12483020</td>
 <td></td>
 </tr>
 <tr>
 <td>0.25% Trypsin-EDTA</td>
 <td>Life Technologies </td>
 <td>25200-72</td>
 <td></td>
 </tr>
 <tr>
 <td>Hanks Balanced Salt Solution</td>
 <td>Sigma Aldrich</td>
 <td>H6648</td>
 <td></td>
 </tr>
 <tr>
 <td>Lipofectamine 2000</td>
 <td>Life Technologies</td>
 <td>11668-019</td>
 <td></td>
 </tr>
 <tr>
 <td>Nikon Eclipse TE2000-5</td>
 <td>Nikon Instruments Inc.</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Xenolight D-luciferin</td>
 <td>PerkinElmer</td>
 <td>122796</td>
 <td>40 mg/ml in PBS</td>
 </tr>
 </tbody>
</table>

molecular imaging to target transplanted muscle progenitor cells

Duchenne muscular dystrophy (DMD) is a severe genetic neuromuscular disorder that affects 1 in 3,500 boys, and is characterized by progressive muscle degeneration1, 2. In patients, the ability of resident muscle satellite cells (SCs) to regenerate damaged myofibers becomes increasingly inefficient4. Therefore, transplantation of muscle progenitor cells (MPCs)/myoblasts from healthy subjects is a promising therapeutic approach to DMD. A major limitation to the use of stem cell therapy, however, is a lack of reliable imaging technologies for long-term monitoring of implanted cells, and for evaluating its effectiveness. Here, we describe a non-invasive, real-time approach to evaluate the success of myoblast transplantation. This method takes advantage of a unified fusion reporter gene composed of genes (firefly luciferase [fluc], monomeric red fluorescent protein [mrfp] and sr39 thymidine kinase [sr39tk]) whose expression can be imaged with different imaging modalities9, 10. A variety of imaging modalities, including positron emission tomography (PET), single-photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), optical imaging, and high frequency 3D-ultrasound are now available, each with unique advantages and limitations11. Bioluminescence imaging (BLI) studies, for example, have the advantage of being relatively low cost and high-throughput. It is for this reason that, in this study, we make use of the firefly luciferase (fluc) reporter gene sequence contained within the fusion gene and bioluminescence imaging (BLI) for the short-term localization of viable C2C12 myoblasts following implantation into a mouse model of DMD (muscular dystrophy on the X chromosome [mdx] mouse)12-14. Importantly, BLI provides us with a means to examine the kinetics of labeled MPCs post-implantation, and will be useful to track cells repeatedly over time and following migration. Our reporter gene approach further allows us to merge multiple imaging modalities in a single living subject; given the tomographic nature, fine spatial resolution and ability to scale up to larger animals and humans10,11, PET will form the basis of future work that we suggest may facilitate rapid translation of methods developed in cells to preclinical models and to clinical applications.

Upon 50-60% confluency, C2C12 myoblasts were transiently transfected with the above-mentioned fusion reporter gene construct composed of firefly luciferase [fluc], monomeric red fluorescent protein [mrfp] and sr39 thymidine kinase [sr39tk](Figure 1A). Transfection efficiency was calculated via fluorescence microscopy (Figures 1B,C), making use of the mrfp sequence in our reporter construct. Cell survivability was not affected by labeling with the BLI s...

Watch this Scientific Journal Video about Molecular Imaging to Target Transplanted Muscle Progenitor Cells at JoVE.com

Molecular Imaging to Target Transplanted Muscle Progenitor Cells

A non-invasive means to evaluate the success of myoblast transplantation is described. The method takes advantage of a unified fusion reporter gene composed of genes whose expression can be imaged with different imaging modalities. Here, we make use of a fluc reporter gene sequence to target cells via bioluminescence imaging.

Duchenne muscular dystrophy (DMD) is a severe genetic neuromuscular disorder that affects 1 in 3,500 boys, and is characterized by progressive muscle ...

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9.1K Views.  Lawson Health Research Institute. A non-invasive means to evaluate the success of myoblast transplantation is described. The method takes advantage of a unified fusion reporter gene composed of genes whose expression can be imaged with different imaging modalities. Here, we make use of a fluc reporter gene sequence to target cells via bioluminescence imaging.

Video: Molecular Imaging to Target Transplanted Muscle Progenitor Cells

In vivo Near Infrared Fluorescence (NIRF) Intravascular Molecular Imaging of Inflammatory Plaque, a Multimodal Approach to Imaging of Atherosclerosis

The vascular response to injury is a well-orchestrated inflammatory response triggered by the accumulation of macrophages within the vessel wall leading to an accumulation of lipid-laden intra-luminal plaque, smooth muscle cell proliferation and progressive narrowing of the vessel lumen. The formation of such vulnerable plaques prone to rupture underlies the majority of cases of acute myocardial infarction. The complex molecular and cellular inflammatory cascade is orchestrated by the recruitment of T lymphocytes and macrophages and their paracrine effects on endothelial and smooth muscle cells.1
Molecular imaging in atherosclerosis has evolved into an important clinical and research tool that allows in vivo visualization of inflammation and other biological processes. Several recent examples demonstrate the ability to detect high-risk plaques in patients, and assess the effects of pharmacotherapeutics in atherosclerosis.4 While a number of molecular imaging approaches (in particular MRI and PET) can image biological aspects of large vessels such as the carotid arteries, scant options exist for imaging of coronary arteries.2 The advent of high-resolution optical imaging strategies, in particular near-infrared fluorescence (NIRF), coupled with activatable fluorescent probes, have enhanced sensitivity and led to the development of new intravascular strategies to improve biological imaging of human coronary atherosclerosis.
Near infrared fluorescence (NIRF) molecular imaging utilizes excitation light with a defined band width (650-900 nm) as a source of photons that, when delivered to an optical contrast agent or fluorescent probe, emits fluorescence in the NIR window that can be detected using an appropriate emission filter and a high sensitivity charge-coupled camera. As opposed to visible light, NIR light penetrates deeply into tissue, is markedly less attenuated by endogenous photon absorbers such as hemoglobin, lipid and water, and enables high target-to-background ratios due to reduced autofluorescence in the NIR window. Imaging within the NIR 'window' can substantially improve the potential for in vivo imaging.2,5
Inflammatory cysteine proteases have been well studied using activatable NIRF probes10, and play important roles in atherogenesis. Via degradation of the extracellular matrix, cysteine proteases contribute importantly to the progression and complications of atherosclerosis8. In particular, the cysteine protease, cathepsin B, is highly expressed and colocalizes with macrophages in experimental murine, rabbit, and human atheromata.3,6,7 In addition, cathepsin B activity in plaques can be sensed in vivo utilizing a previously described 1-D intravascular near-infrared fluorescence technology6, in conjunction with an injectable nanosensor agent that consists of a poly-lysine polymer backbone derivatized with multiple NIR fluorochromes (VM110/Prosense750, ex/em 750/780nm, VisEn Medical, Woburn, MA) that results in strong intramolecular quenching at baseline.10 Following targeted enzymatic cleavage by cysteine proteases such as cathepsin B (known to colocalize with plaque macrophages), the fluorochromes separate, resulting in substantial amplification of the NIRF signal. Intravascular detection of NIR fluorescence signal by the utilized novel 2D intravascular NIRF catheter now enables high-resolution, geometrically accurate in vivo detection of cathepsin B activity in inflamed plaque.
In vivo molecular imaging of atherosclerosis using catheter-based 2D NIRF imaging, as opposed to a prior 1-D spectroscopic approach,6 is a novel and promising tool that utilizes augmented protease activity in macrophage-rich plaque to detect vascular inflammation.11,12 The following research protocol describes the use of an intravascular 2-dimensional NIRF catheter to image and characterize plaque structure utilizing key aspects of plaque biology. It is a translatable platform that when integrated with existing clinical imaging technologies including angiography and intravascular ultrasound (IVUS), offers a unique and novel integrated multimodal molecular imaging technique that distinguishes inflammatory atheromata, and allows detection of intravascular NIRF signals in human-sized coronary arteries.

In vivo Near Infrared Fluorescence NIRF Intravascular Molecular Imaging of Inflammatory Plaque, a Multimodal Approach to Imaging of Atherosclerosis

We detail a new near-infrared fluorescence (NIRF) catheter for 2-dimensional intravascular molecular imaging of plaque biology in vivo. The NIRF catheter can visualize key biological processes such as inflammation by reporting on the presence of plaque-avid activatable and targeted NIR fluorochromes. The catheter utilizes clinical engineering and power requirements and is targeted for application in human coronary arteries. The following research study describes a multimodal imaging strategy that utilizes a novel in vivo intravascular NIRF catheter to image and quantify inflammatory plaque in proteolytically active inflamed rabbit atheromata.

The vascular response to injury is a well-orchestrated inflammatory response triggered by the accumulation of macrophages within the vessel wall leading ...

Labeling Stem Cells with Ferumoxytol, an FDA-Approved Iron Oxide Nanoparticle

Stem cell based therapies offer significant potential for the field of regenerative medicine. However, much remains to be understood regarding the in vivo kinetics of transplanted cells. A non-invasive method to repetitively monitor transplanted stem cells in vivo would allow investigators to directly monitor stem cell transplants and identify successful or unsuccessful engraftment outcomes.
A wide range of stem cells continues to be investigated for countless applications. This protocol focuses on 3 different stem cell populations: human embryonic kidney 293 (HEK293) cells, human mesenchymal stem cells (hMSC) and induced pluripotent stem (iPS) cells. HEK 293 cells are derived from human embryonic kidney cells grown in culture with sheared adenovirus 5 DNA. These cells are widely used in research because they are easily cultured, grow quickly and are easily transfected. hMSCs are found in adult marrow. These cells can be replicated as undifferentiated cells while maintaining multipotency or the potential to differentiate into a limited number of cell fates. hMSCs can differentiate to lineages of mesenchymal tissues, including osteoblasts, adipocytes, chondrocytes, tendon, muscle, and marrow stroma. iPS cells are genetically reprogrammed adult cells that have been modified to express genes and factors similar to defining properties of embryonic stem cells. These cells are pluripotent meaning they have the capacity to differentiate into all cell lineages 1. Both hMSCs and iPS cells have demonstrated tissue regenerative capacity in-vivo.
Magnetic resonance (MR) imaging together with the use of superparamagnetic iron oxide (SPIO) nanoparticle cell labels have proven effective for in vivo tracking of stem cells due to the near microscopic anatomical resolution, a longer blood half-life that permits longitudinal imaging and the high sensitivity for cell detection provided by MR imaging of SPIO nanoparticles 2-4. In addition, MR imaging with the use of SPIOs is clinically translatable. SPIOs are composed of an iron oxide core with a dextran, carboxydextran or starch surface coat that serves to contain the bioreactive iron core from plasma components. These agents create local magnetic field inhomogeneities that lead to a decreased signal on T2-weighted MR images 5. Unfortunately, SPIOs are no longer being manufactured. Second generation, ultrasmall SPIOs (USPIO), however, offer a viable alternative. Ferumoxytol (FerahemeTM) is one USPIO composed of a non-stoichiometric magnetite core surrounded by a polyglucose sorbitol carboxymethylether coat. The colloidal, particle size of ferumoxytol is 17-30 nm as determined by light scattering. The molecular weight is 750 kDa, and the relaxivity constant at 2T MRI field is 58.609 mM-1 sec-1 strength4. Ferumoxytol was recently FDA-approved as an iron supplement for treatment of iron deficiency in patients with renal failure 6. Our group has applied this agent in an &ldquo;off label&rdquo; use for cell labeling applications. Our technique demonstrates efficient labeling of stem cells with ferumoxytol that leads to significant MR signal effects of labeled cells on MR images. This technique may be applied for non-invasive monitoring of stem cell therapies in pre-clinical and clinical settings.

We describe a technique for labeling and tracking stem cells with FDA-approved, superparamagnetic iron oxide (SPIO), ferumoxytol (Feraheme). This cellular imaging technique that utilizes magnetic resonance (MR) imaging for visualization, is readily accessible for long-term monitoring and diagnosis of successful or unsuccessful stem cell engraftments in patients.

Stem cell based therapies offer significant potential for the field of regenerative medicine. However, much remains to be understood regarding the in vivo ...

The Use of Thermal Infra-Red Imaging to Detect Delayed Onset Muscle Soreness

Delayed onset muscle soreness (DOMS), also known as exercise induced muscle damage (EIMD), is commonly experienced in individuals who have been physically inactive for prolonged periods of time, and begin with an unexpected bout of exercise1-4, but can also occur in athletes who exercise beyond their normal limits of training5. The symptoms associated with this painful phenomenon can range from slight muscle tenderness, to severe debilitating pain1,3,5. The intensity of these symptoms and the related discomfort increases within the first 24 hours following the termination of the exercise, and peaks between 24 to 72 hours post exercise1,3. For this reason, DOMS is one of the most common recurrent forms of sports injury that can affect an individual&#x2019;s performance, and become intimidating for many1,4.
For the last 3 decades, the DOMS phenomenon has gained a considerable amount of interest amongst researchers and specialists in exercise physiology, sports, and rehabilitation fields6. There has been a variety of published studies investigating this painful occurrence in regards to its underlying mechanisms, treatment interventions, and preventive strategies1-5,7-12. However, it is evident from the literature that DOMS is not an easy pathology to quantify, as there is a wide amount of variability between the measurement tools and methods used to quantify this condition6. It is obvious that no agreement has been made on one best evaluation measure for DOMS, which makes it difficult to verify whether a specific intervention really helps in decreasing the symptoms associated with this type of soreness or not. Thus, DOMS can be seen as somewhat ambiguous, because many studies depend on measuring soreness using a visual analog scale (VAS)10,13-15, which is a subjective rather than an objective measure. Even though needle biopsies of the muscle, and blood levels of myofibre proteins might be considered a gold standard to some6, large variations in some of these blood proteins have been documented 6,16, in addition to the high risks sometimes associated with invasive techniques. 
Therefore, in the current investigation, we tested a thermal infra-red (IR) imaging technique of the skin above the exercised muscle to detect the associated muscle soreness. Infra-red thermography has been used, and found to be successful in detecting different types of diseases and infections since the 1950&#x2019;s17. But surprisingly, near to nothing has been done on DOMS and changes in skin temperature. The main purpose of this investigation was to examine changes in DOMS using this safe and non-invasive technique.

The purpose of this investigation was to assess whether using an infra-red thermal camera is a valid tool for detecting and quantifying the muscle soreness after exercising.

Delayed onset muscle soreness (DOMS), also known as exercise induced muscle damage (EIMD), is commonly experienced in individuals who have been physically ...

MR Molecular Imaging of Prostate Cancer with a Small Molecular CLT1 Peptide Targeted Contrast Agent

Tumor extracellular matrix has abundance of cancer related proteins that can be used as biomarkers for cancer molecular imaging. In this work, we demonstrated effective MR cancer molecular imaging with a small molecular peptide targeted Gd-DOTA monoamide complex as a targeted MRI contrast agent specific to clotted plasma proteins in tumor stroma. We performed the experiment of evaluating the effectiveness of the agent for non-invasive detection of prostate tumor with MRI in a mouse orthotopic PC-3 prostate cancer model. The targeted contrast agent was effective to produce significant tumor contrast enhancement at a low dose of 0.03 mmol Gd/kg. The peptide targeted MRI contrast agent is promising for MR molecular imaging of prostate tumor.

To demonstrate MR cancer molecular imaging with a small peptide targeted MRI contrast agent specific to clotted plasma proteins in tumor stroma in a mouse prostate cancer model.

Tumor extracellular  matrix has abundance of cancer related proteins that can be used as biomarkers  for cancer molecular imaging. In this work,  we ...

High-throughput Flow Cytometry Cell-based Assay to Detect Antibodies to N-Methyl-D-aspartate Receptor or Dopamine-2 Receptor in Human Serum

Over the recent years, antibodies against surface and conformational proteins involved in neurotransmission have been detected in autoimmune CNS diseases in children and adults. These antibodies have been used to guide diagnosis and treatment. Cell-based assays have improved the detection of antibodies in patient serum. They are based on the surface expression of brain antigens on eukaryotic cells, which are then incubated with diluted patient sera followed by fluorochrome-conjugated secondary antibodies. After washing, secondary antibody binding is then analyzed by flow cytometry. Our group has developed a high-throughput flow cytometry live cell-based assay to reliably detect antibodies against specific neurotransmitter receptors. This flow cytometry method is straight forward, quantitative, efficient, and the use of a high-throughput sampler system allows for large patient cohorts to be easily assayed in a short space of time. Additionally, this cell-based assay can be easily adapted to detect antibodies to many different antigenic targets, both from the central nervous system and periphery. Discovering additional novel antibody biomarkers will enable prompt and accurate diagnosis and improve treatment of immune-mediated disorders.

Over the recent years, live cell-based assays have been used successfully to detect antibodies against surface and conformational antigens. Here, we describe a method using high-throughput flow cytometry enabling the analysis of large cohorts of patients. Detection of novel antibodies will improve diagnosis and treatment of immune-mediated disorders.

Over the recent years, antibodies against surface and conformational proteins involved in neurotransmission have been detected in autoimmune CNS diseases ...

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 ...

Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease

Quantitative magnetic resonance imaging (qMRI) describes the development and use of MRI to quantify physical, chemical, and/or biological properties of living systems. Neuromuscular diseases often exhibit a temporally varying, spatially heterogeneous, and multi-faceted pathology. The goal of this protocol is to characterize this pathology using qMRI methods. The MRI acquisition protocol begins with localizer images (used to locate the position of the body and tissue of interest within the MRI system), quality control measurements of relevant magnetic field distributions, and structural imaging for general anatomical characterization. The qMRI portion of the protocol includes measurements of the longitudinal and transverse relaxation time constants (T1 and T2, respectively). Also acquired are diffusion-tensor MRI data, in which water diffusivity is measured and used to infer pathological processes such as edema. Quantitative magnetization transfer imaging is used to characterize the relative tissue content of macromolecular and free water protons. Lastly, fat-water MRI methods are used to characterize fibro-adipose tissue replacement of muscle. In addition to describing the data acquisition and analysis procedures, this paper also discusses the potential problems associated with these methods, the analysis and interpretation of the data, MRI safety, and strategies for artifact reduction and protocol optimization.

Neuromuscular diseases often exhibit a temporally varying, spatially heterogeneous, and multi-faceted pathology. The goal of this protocol is to characterize this pathology using non-invasive magnetic resonance imaging methods.

Quantitative magnetic resonance imaging (qMRI) describes the development and use of MRI to quantify physical, chemical, and/or biological properties of ...

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 ...

Calcification of Vascular Smooth Muscle Cells and Imaging of Aortic Calcification and Inflammation

Cardiovascular disease is the leading cause of morbidity and mortality in the world. Atherosclerotic plaques, consisting of lipid-laden macrophages and calcification, develop in the coronary arteries, aortic valve, aorta, and peripheral conduit arteries and are the hallmark of cardiovascular disease. In humans, imaging with computed tomography allows for the quantification of vascular calcification; the presence of vascular calcification is a strong predictor of future cardiovascular events. Development of novel therapies in cardiovascular disease relies critically on improving our understanding of the underlying molecular mechanisms of atherosclerosis. Advancing our knowledge of atherosclerotic mechanisms relies on murine and cell-based models. Here, a method for imaging aortic calcification and macrophage infiltration using two spectrally distinct near-infrared fluorescent imaging probes is detailed. Near-infrared fluorescent imaging allows for the ex vivo quantification of calcification and macrophage accumulation in the entire aorta and can be used to further our understanding of the mechanistic relationship between inflammation and calcification in atherosclerosis. Additionally, a method for isolating and culturing animal aortic vascular smooth muscle cells and a protocol for inducing calcification in cultured smooth muscle cells from either murine aortas or from human coronary arteries is described. This in vitro method of modeling vascular calcification can be used to identify and characterize the signaling pathways likely important for the development of vascular disease, in the hopes of discovering novel targets for therapy.

Vascular calcification is an important predictor of and contributor to human cardiovascular disease. This protocol describes methods for inducing calcification of cultured primary vascular smooth muscle cells and for quantifying calcification and macrophage burden in animal aortas using near-infrared fluorescence imaging.

Cardiovascular disease is the leading cause of morbidity and mortality in the world.  Atherosclerotic plaques, consisting of lipid-laden macrophages and ...

Contractility Measurements of Human Uterine Smooth Muscle to Aid Drug Development

Discovery and characterization of novel pharmaceutical compounds or biochemical probes rely on robust and physiologically relevant assay systems. We describe methods to measure ex vivo myometrium contractility. This assay can be used to investigate factors and molecules involved in the modulation of myometrial contraction and to determine their excitatory or inhibitory actions, and hence their therapeutic potential in vivo. Biopsies are obtained from women undergoing cesarean section delivery with informed consent. Fine strips of myometrium are dissected, clipped and attached to a force transducer within 1 mL organ baths superfused with physiological saline solution at 37 &#176;C. Strips develop spontaneous contractions within 2&#8211;3 h under set tension and remain stable for many hours (&#62;6 h). Strips can also be stimulated to contract such as by the endogenous hormones, oxytocin and vasopressin, which cause concentration-dependent modulation of contraction frequency, force and duration, to more closely resemble contractions in labor. Hence, the effect of known and novel drug leads can be tested on spontaneous and agonist-induced contractions.
This protocol specifically details how this assay can be used to determine the potency of known and novel agents by measuring their effects on various parameters of human myometrial contraction. We use the oxytocin- and V1a receptor antagonists, atosiban and SR49059 as examples of known compounds which inhibit oxytocin- and vasopressin-induced contractions, and demonstrate how this method can be used to complement and validate pharmacological data obtained from cell-based assays to aid drug development. The effects of novel agonists in comparison to oxytocin and vasopressin can also be characterized. Whilst we use the example of the oxytocin/ vasopressin system, this method can also be used to study other receptors and ion channels that play a role in uterine contraction and relaxation to advance the understanding of human uterine physiology and pathophysiology.

This article describes experimental protocols to study ex vivo contractions of human myometrium and their application in drug discovery. This technique is used to improve the understanding of myometrial physiology and pathophysiology as well as to validate pharmacological data from novel research probes or drug leads.

Discovery and characterization of novel pharmaceutical compounds or biochemical probes rely on robust and physiologically relevant assay systems. We ...