Effects Of Topical Application Of Small Dose Insulin On The Revascularization Process To The Acellular Dermal Substitutes After The Grafting

ObjectiveTo investigate the effects of topical application of small dose of insulin is to the revascularization process in the acellular dermal substitutes after the grafting.Methods1. To produce the swine acellular dermal matrix;Use the vertebral column as center to get skin and disinfect it. Execute the shin patch to 10 10cm and 0. 5 mm thick. Process it with10% sodium chloride solution at constant temperature 37℃ for 24 -48h. Then clean the saline and tear the epidermis. First drip it in the 5% sodium hydrogen carbonate solution for 30 minutes and then drip it in 0. 25% trypsin and 0.1% EDTA at 37℃ for 90 minutes. After using asepsis saline to clean it, made it to reticulation. It is conserved at 2 -8℃.2. 144 rats were enrolled in the study and were randomly divided into group A,B and C(under sADM injection of 0. 1U,0. 05U and 0. 01U insulin into the rats) and D (under sADM injection of isotonic saline into the rats as control). To inject every other day until the 13 day after grafting . The tissue biopsies were harvested at 1,2,3,4,7,10,14,21,28 post grafting day ( PGD) for the observation of the revascularization process, and blood glucose concentration of each group was determined.Results1. The blood glucose levelThe blood glucose level of BNC and D groups fluctuated from 4. 0 to 8. 40mmol/L at 6 PGH, while that in group A decreased obviously 1 hour after in-jection( P<0. 01).2. Histological and macroscopic observation of acellular dermal substitutes after grafting2.1 macroscopic observationThe conjugation between the acellular dermal substitutes and the wound surface was satisfied on the every view time point after the transplant.On the 14th day after grafted, there were so affluent vasoganglions in the fascia which had wrapped up the acellular dermal substitutes, the density was higher than the control group.2. 2 Histological observationNo cell can be seen in the sADM before the grafting. In A and B group, two days after the grafting, there were lots of fibroblasts and inflammatory cells in the superficial layer of transplant. 4 days after the grafting, there were a lot of vascular endothelial cells. (P <0. 05)7 days after the grafting, new entire capillaries were detected at the superficial layer of transplant. Fourteen days after the grafting, more blood vessels can be seen in A and B groups. There were no significant difference at the numbers and caliber among each group 28 days after the grafting.DiscussionThe Vascular endothelial cells will be enhanced in many aspects such as the cytodieresis ^proliferation ^ migration and vasopermeability on the condition that the acellular dermal substitutes combined with Vascular endothelial cell growth factor(VEGF) receptors. And as the result, the vasculogenesis will be certainly rasised. With the interaction of the vascular endothelial cells and fibro-blasts, the vasculogenesis will take place further more. The insulin induct the VEGF mRNA expression throuth various different signal paths. Also the insulin plays the role of promoting the proliferation of fibroblasts and the synthesis of the collogen, supporting the activity of fibroblasts. So we begin to study the insulin which has the action on both the vascular endothelial cells and the fibroblasts. Since the insulin has the positive effects on the vascular endothelial cells' cytodi-eresis ^proliferation and VEGF expression, we plan to transplant the sADM into the rats subcutaneously and do the local infiltration as the second step, then the artificial environment will benefit the cells' cytodieresis and proliferation. Not only the dermal matrix will has the vitality, but also the vascular endothelial cells will generate faster for the effect of VEGF in the matrix. The fibroblasts also excrete cytokines^ growth factors and elements of extracellular matrix which help to enhance the affinity of dermal substitutes and the vasculogenesis. It maybe the cytological base of the dermal matrixes vasculogenesis being promoted by insulin. The design not only saves the time, but also omits the complicate course of taking the samples and cell culture, reaches the aim that it may provide the best conditions for rapid vasculogenesis of acellular dermal substitutes.ConclusionLocal injection of small dose of insulin can obviously promote the earlier period revascularization of acellular dermal substitutes.