الفهرس 
coverOnly 14 pages are availabe for public view
 |  | from | 148 |  |  |
| | | from | 148 | | |
Abstract
MSCs are a heterogenous population of pluripotent non hematopoietic cells that proliferate in vitro as plastic adherent cells, with fusiform, fibroblast like morphology, isolated from bone marrow and other sources. They are capable of self renewal as well as multilineage differentiation into mesodermal cells as osteoblasts, adipocytes and chondrogenic cells and possibly, but still controversial, they can transdifferentiate into other non mesodermal cells as neural cells and hepatocytes. They are capable of restoring the hematopoietic microenvironment after back-transplantation of even a single clone into the body (Abdallah and Kassem, 2008 and Uccelli et al., 2008).
MSCs do not express Major histocomptability complex type II (MHC II) rendering them non immunogenic, thus precluding the need for lifelong immunosuppression with allogenic transplantation (Schipani and Kronenberg, 2008).
Experiments on animals demonstrated the capacity of locally administered stromal precursors to heal the lesions in the bone, articular cartilage, tendon and skin (Kruglyakov et al., 2004). Recently, the use of MSCs have been tried in a small number of patients with vascular ischemia secondary to peripheral arterial disease, coronary artery disease or non-healed chronic skin wounds. The injected cells were well tolerated. However, these initial encouraging results need to be confirmed in randomized clinical trials with adequate number of patients (Abdallah and Kassem, 2008).
The aim of this study was to examine the effect of local delivery of MSCs on muscle regeneration in a murine limb ischemia model.
The study was done on 45 male white Albino rats belonging to local strain weighing between 150-170 gm and were obtained from the Animal House of Faculty of Medicine, Cairo University and included in this study.
Rat hindlimb ischemia model was established by surgical ligation of the left femoral artery under anesthesia with pentobarbital (50 mg /kg, intraperitoneal). Animals were grouped as; control rats (n = 15) received IM injection of saline without cells; ischemic group (n=15) subjected to surgical left femoral artery ligation, and ischemic injected with hMSCs group (n=15) that subjected to surgical left femoral artery ligation with IM injection of 5× 106 hMSCs/ rat suspended in 0.5ml PBS one week after ligation at 3 different sites.
In vitro, hMSCs were isolated from human bone marrow aspiration and characterization was assessed by flow cytometry following culture. In vitro hMSCs were labeled by red fluorescent PKH dye for tissue tracing after cell transplantation. Muscle performance, peak isometric twitch force (Pt) was assessed 4 weeks after surgery. After rats were sacrificed, muscle tissues of the three studied groups were harvested for pathological assessment, tissue tracing of labeled MSCs and for vascular endothelial growth factor gene expression using quantitative real time PCR.
Our results showed that hMSCs by flow cytometry after culture were positive for mesenchymal stem cell marker (CD90, CD105, CD29) and, negative for panleucocytic marker (CD45), hematopoietic stem cell marker (CD34).
Assessment of muscle contractile performance in the 3 studied groups detected that ischemic with MSCs injected group showed significant increase in the Pt value compared to the ischemic group (P<0.05), while showed insignificant difference in the Pt value compared to the control group (P>0.05). In addition, both control and hMSC-treated groups showed significant increase in Pt value compared to the ischemic group (P< 0.05).
At the histopathological levels, ischemic transplanted muscle with hMSCs showed definite angiogenesis, neovascularization and collateral formation.
Red fluorescent PKH dye for tissue tracing after cell transplantation showed that the red fluorescence was not detected in control shamed muscle but it was found in ischemic hindlimb rats treated with MSCs, confirming that these transplanted labeled cells were actually seeded into the muscle tissue.
The molecular assessment of human VEGF gene in the muscle tissue of the 3 studied groups was detected by qPCR assay. The expression of VEGF significantly increased in the ischemic with hMSCs group than in the control group (p < 0.05). Moreover, the expression of VEGF was higher in hMSCs group compared with that in the ischemic group (p < 0.05).
CONCLUSION
• In conclusion, our findings seem to suggest an influence of xenotransplantatin of hMSCs in a rat model of hindlimb ischemia on angiogenesis through improved neovascularization and increased VEGF levels. Also, an improved contractile muscle performance was confirmed in the ischemic MSCs injected group.