OBJECTIVEExperimental study on the survival rate of random flap using vascular endothelial growth factor (VEGF) and bone marrow mesenchymal stem cell (MSC).

METHODSMSC was isolated through the combined utilization of density gradient centrifugation and adherence screening methods. MSC was cultured and its purity and biological properties were identified. Forty Wistar rat models were established and divided into control group, VEGF group, MSC group and MSC+VEGF group. Designed 2 cm x 5 cm pedicle flap on each rat's back. The flaps were observed for 14 d after operation. On the 14th day, the rats were killed. The survival rates of random flap in each group were counted, and the histological sections were stained at the flap which was 4 cm far from the pedicle, and the number of microvascular was observed.

RESULTS1) MSC was detected by flow cytometry, adipogenic and osteogenic induction detection. The results showed that MSC could differentiate to fat and cartilage by induction and certified that the MSC had multi-differentiation potential. 2) Immune rejection did not appear on each animal. The survival rate of random flap in control group, VEGF group, MSC group and MSC+VEGF group were 55.4% +/- 4.4%, 70.7% +/- 6.3%, 65.1% +/- 7.1%, and 93.4% +/- 9.4%, respectively. The survival rate of each experimental group was higher than control group (P < 0.05). The survival rate of MSC+VEGF group was the highest (P < 0.05). 3) The histological examination showed that the granulation tissue, fibroblast and neovascularity was most abundant in MSC+VEGF group.

CONCLUSION1)The purified and multi-differentiated MSC can be obtained by density gradient centrifugation and adherence screening methods. 2) The human MSC has no immunogens or minimal immunogenicity, immunological would not be caused when it is transmitted in cross-species. 3) VEGF and MSC have synergetic effect when they are used together, it can rebuild the blood circulation of the ischemic region in a short time, solve ischemia of the flap far from the pedicle, improve survival rate of the flap and enhance the repair quality of the wound.