الفهرس | Only 14 pages are availabe for public view |
Abstract Random-pattern skin flap is one of the most widely used tools in the repair of tissue defects in plastic surgery. However, its utility is limited by unpredictable blood supply, which sometimes results in partial flap necrosis which represents a great challenge. This problem therefore limits the use of random-pattern skin flaps. Different methods to improve skin flap survival have been employed which may be pharmacological or surgical. Surgical delay and ischemic preconditioning is the most effective method of increasing survival area. However, the delay procedure requires an additional operative procedure. Many researchers have focused on drug therapy as an alternative method for augmenting blood flow rather than the time consuming surgical delay. The pharmacological drugs mimics the surgical delay, however, the effects of drugs are transient and unstable. VEGF, bFGF, PDGF, and TGF-β has been shown to augment flap vascularity and reduce skin flap necrosis. However, their utility is limited by their short duration and the need for high doses and frequent injections which leads to many side effects. Stem cells have emerged as a key element of regenerative medicine. Stem cell therapy has aroused an interest in improving flap survival, especially bone marrow derived stem cells and adipose derived stem cells. Supplemental administration of angiogenic growth factors such as BMMSCs transplantation has many advantages including abundance in the bone marrow and easy isolation. BM-MSCs are also a heterogenous population of cells, which have been shown more beneficial than homogenous composition in therapeutic vascularization. Also high levels of angiogenic growth factors such as VEGF and bFGF could be maintained by transplanted BM-MSCs. In addition BM-MSCs can be transplanted directly without in vitro expansion. All these properties make BMSCs a good source of mesenchymal stem cells. BM-MSCs exert their effect by their ability to produce angiogenic growth factors such as VEGF, PDGF, and bFGF. Also, BM-MSCs could differentiate into endothelial cells to participate in neovascularization. In our research, we studied the role of bone marrow derived stem cells whether cultured under normoxic or hypoxic conditions on the random skin flap survival in a rat model, and the optimal timing for administration of these cells. Our study consisted of three main groups; group A injected with normoxic bone marrow stem cells, group B injected with hypoxic bone marrow derived stem cells and group C which is the control group, Each group is further subdivided into two subgroups according to the time of flap injection, The subgroup 1 is injected at time of flap elevation, and subgroup 2 which is injected one week before flap elevation. Flap survival was evaluated on the seventh postoperative day by: the percentage of flap survival, capillary density and VEGF level by ELISA. BM-MSCs showed statistically significant increase in skin flap viability when injected simultaneously with time of flap elevation, however, BM-MSCs had no effect on flap survival when injected one week preoperatively. The maximal effect was observed when the hypoxic cells were injected simultaneously with flap elevation. This was in accordant with the significant increase of the capillary density and VEGF expression. |