| Regeneration and repair of skin tissue trauma is a common problemand challenge in burn and plastic surgery, especially for the repair of softtissue defects. Repair methods currently used in clinic include Lasertreatment for patients with mild degree of defect which need long course oftreatment and cause has instable effects pigmentation. Biological materialfilling such as bovine collagen, autologous collagen, hyaluronic acid andothers. Which is simple, quick and cause little damage but has theshortcomings of short maintenance time, high costs and material leakage.Surgical suture removal which may leave obvious scar. Flap surgery whichrequires high technical skills and can cause damage to the donor site.Compared to other biological filling materials, autologous fat has theadvantage of good histocompatibility and no foreign body rejection.Autologous fat transplantation as an ideal soft tissue filling agent has theadvantages of easiness to operate and cause little injury to donor site.Numerous studies show that non-vascularized autologous fat grafts have alot of fat cell death due to its less tolerance to ischemia and hypoxia. Butthe native tissue stem or progenitor cells can differentiate into adipocytesand endothelial cells. Therefore, to promote early cell proliferation andangiogenesis of graft adipose tissue by increasing the adipose derivedmesenchymal stem cells (Adipose-derived stem cells, ADSCs) has becomethe key point to improve the survival rate of transplanted fat. Especially, theinvention of cell-assisted lipotransfer provides a new method for theclinical application of fat grafting. ADSCs as seed cells are widely used toassist transplant. But autologous ADSCs’ source is limited and its long cycle time in vitro limits its clinical application. Studies show thatallogeneic ADSCs have low immunogenicity, and can induce immunetolerance. Therefore, we performed exploratory experimental of fattransplantation in SD rats by using the method of allogeneic stem cellauxiliary autologous fat transplantation, trying to prove that allogeneicstem cell graft can improve the survival rate of transplantation byshortening the time of adipose tissue ischemia and hypoxia, so as toimprove early vascular of graft. So we can provide preliminary animalexperiment data and the experimental evidence for the further study.At first, by collagenase digestion method, we separated and culturedSD rat ADSCs in vitro. The cultured ADSCs were mainly spindle-shapedand whirlpool-shaped arranged, mixed with non-adherent spherical orcircular cells. The cell growth curve showed3days later. The cells was inthe logarithmic growth phase, while the tenth generation cells growthslower than the fourth generation. The cells were identified by adipogenicand osteogenic differentiation. Cellular surface antigens were examined byusing flow cytomety. Tan nodules and red lipid droplets can be found afterstained with alizarin red and oil red O. The fourth passage ADSCs werepositive for CD34and CD49d, negative for CD106and CD45.Secondly,32healthy SD rat were divided into four groups randomlyaccording to the random number table: A allogeneic adipose granule(AG),B autologous adipose granule(AG), C autologous adipose granule(AG) andautologous ADSCs, D allogeneic ADSCs and autologous adiposegranule(AG). The fat was injected subcutaneously in the back of rat.7dayslater, we examined the graft. The graft wet weight was measured andimmunohistochemical method(CD31) was performed. Data were processedwith one-way ANOVA of variance and LSD-t test. At7days aftertransplantation, the difference of the two groups A(0.252±0.04),B(0.265±0.03) and group C(0.36±0.03), D(0.35±0.04) were statisticalsignificant (P＜0.05). The CD31positive cells of group D(22.68±1.03), C(20.53±1.07) were significantly more than those of group A(7.97±3.61),B(10.93±1.68) at7days.The results of this study show that: the first ADSCs SD rats weresuccessfully isolated and cultured in vitro. The second Allogeneic ADSCscombined with AG can improve the fat graft survival rate in SDrats. Thethrit allogeneic adipose-derived mesenchymal stem cells had distribution ofgreen fluorescence in the subcutaneous transplantation adipose tissue. Thelast allogeneic ADSCs have the same effect as autologous stem cell in fattransplantation by contribute to the early fat graft vascularization. Thedifference in wet weight of fat is still statistically significant.Allogeneic stem cell assisted autologous fat transplantation isapplicable in experimental study of SD rats fat transplantation. AllogeneicADSCs combined with autogenous AG in SD rats can significantlyimprove the survival rate of fat transplantation. The mechanism maybe isshorten SD adipose tissue ischemia and hypoxia by improving thevasclarization level of graft adipose tissue in early period. |
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