PURPOSE: To examine the fate of muscle-derived stem cells (MDSC) after injection into different host conditions and provide an insight for their mechanism of action. MATERIALS AND METHODS: MDSCs differentiated in vitro towards the endothelial lineage and transfected with lentivirus tagged with green fluorescent protein (GFP) were injected into two animal models mimicking vascular diseases: hindlimb ischemia and carotid injury models. Injected cells were tracked at the site of injection and in remote organs by harvesting the respective tissues at different time intervals and performing immunofluorescent histological analyses. Stem cell survival was quantified at the site of injection for up to 4 weeks. RESULTS: MDSCs were successfully tagged with fluorescent material GFP and showed successful implantation into the respective injection sites. These cells showed a higher affinity to implant in blood vessel walls as shown by double fluorescent co-stain with CD31. Quantification of stem cell survival showed a time-dependent decrease from day 3 to 4 weeks (survival rate normalized against day 3 was 72.0% at 1 week, 26.8% at 2 weeks and 2.4% at 4 weeks). Stem cells were also fo und in distant organs, especially the kidneys and liver, which survived up to 4 weeks. CONCLUSION: MDSCs were successfully tracked in different vascular disease models, and their fate was assessed in terms of cell survival and distribution. Better understanding of the donor cell properties, including their interaction with the host conditions and their mechanism of action, are needed to enhance cell survival and achieve improved outcomes.
Adult Stem Cells ; Animals ; Blood Vessels ; Cell Survival ; Hindlimb ; Humans ; Ischemia ; Kidney ; Lentivirus ; Liver ; Models, Animal ; Stem Cell Niche ; Stem Cells* ; Tissue Donors ; Vascular Diseases

PURPOSE: Lymphedema is a disease with a poorly understood pathogenesis and without definite ways of treatment, yet it can lead to serious complications. The purpose of this study was to establish a new lymphedema mouse model and to evaluate its usefulness for future studies. METHODS: A lymphedema model was created by interrupting flow from the superficial lymphatic system (skin and subcutaneous tissue removal, electrocautery) and the deep lymphatic system (hindlimb muscle resection, dye injection, and inguinal lymph node dissection). The lymphedema group (n=10) was compared to a control group (n=10) by assessing the differences in hindlimb edema, through the use of a water displacement volumetry method. In addition, lymphoscintigraphy, immunohistochemistry, and reverse transcription- polymerase chain reaction (RT-PCR) were performed and compared between the 2 groups. RESULTS: Volumetric analysis showed that the lymphedema group had a 2-fold increase in swelling compared to the control group at study day 3; this gradually decreased to normal levels after 8 weeks. Staining showed an increase in fibrosis in the lymphedema group, as well as an increase in vascular endothelial growth factor receptor-3, a receptor specific for lymphatic cells. RT-PCR showed that there was increased expression of the lymphatic cell specific markers, Prox-1 and podoplanin, in the distal portion of the hindlimb. Lymphoscintigraphy showed retention of lymphatic flow after 30 minutes, however, eventually all of the radioactive substance drained out from the hindlimb. CONCLUSION: Our method for creation of lymphedema in mice was effective in creating acute lymphedema. However it failed to retain its edematous properties for long periods of time. Further studies are needed to create a novel method of chronic lymphedema.
Animals ; Displacement (Psychology) ; Edema ; Fibrosis ; Hindlimb ; Immunohistochemistry ; Lymph Nodes ; Lymphatic System ; Lymphedema ; Lymphoscintigraphy ; Mice ; Muscles ; Polymerase Chain Reaction ; Retention (Psychology) ; Subcutaneous Tissue ; Vascular Endothelial Growth Factor Receptor-3 ; Water