Survival And Generation Of Adipose Tissue In Tissue Engineering Chamber In Vivo

Fat graft has a wide range of applications in plastic surgery. Application of tissue engineering to tissue engineering chamber opens the door for refinement of current adipose tissue–engineering approaches. The aim of this study is to learn pedicle fat flaps and free fat graft survival in tissue engineering chamber and induction of its own de novo adipogenesis, in order to better promote the survival of graft fat tissue and further elucidate the mechanism of de novo adipogenesis.Pedicle fat grafts because of its immediate reconstruction of blood circulation with microsurgical technique, the volume reduction after transplantation is low, these approach can achieve the best results of fat graft. However, limited donor area, harvested a lot of fat easily lead to secondary deformity, which limit the pedicle fat flap in clinical application. Free fat graft for simple operation, combined with the widespread launch of liposuction techniques, making fat graft more popular in clinical practice. However, after fat graft, volume reduction is up to 70%, its unpredictability and high absorption rate limits its clinical application.In vivo tissue engineering chamber which was made of Bio-inert material can provide a good growing space for tissue engineering. If transfer the blood vessels into it, natural vascular network extensions were generated by blood vessels sprouting , these can provide the base of agiogenesis and nutrients for tissues in chamber. Chambers with perforated walls can better promote the growth of constructs indoor, the reason was increasing the exchange of nutrients inside and outside. In vivo tissue engineering chamber constructed a relatively independent space which facilitate the study of a specific tissue organization.The aim of this study in rabbits using pedicle flap which was inset into silicon produced tissue engineering chamber, can grow to larger volume, so as fat flap to the skin after expansion by the expander from small to big, in order to reduce secondary deformity after transplantation, and to provide more adipose tissue to repair the defect. Tissue engineering chamber with perforated wall can accumulate exudation, we also want to find if this exudation be able to support the survival and growth of autologous fat, do some research on the exudation in tissue engineering chamber, and explore the survive and induction of xenograft fat in tissue engineering chamber.1. Study of spontaneous adipose tissue generation of vascularized pedicled fat flap inside tissue engineering chamber:Objective To explore the application of tissue engineering chamber in in vivo adipose tissue engineering ;to establish a model of spontaneous generation of new adipose tissue from an existing fat flap . Methods A defined volume of fat flap based on the superficial inferior epigastric vascular pedicle was elevated and inset into a hollow silicon chamber implanted subcutaneously in the groin of the rabbit. The contents were analyzed after being in situ for 6 weeks. Results The total volume of construct in all tissue engineering chambers increased significantly, from0.5225±0.031ml baseline compared to 3.7625±0.106ml. The volume of the fat flap which included the adipocyte and blood vessels volume increased from 0.5225±0.031ml at insertion to3.01±0.135ml(476% increase) in the perforated silicon chambers. Histomorphometric analysis rather than simple hypertrophy documented an increased number of adipocytes. The new tissue was highly vascularized and no fat necrosis or atypical changes were observed. Conclusion A novel method of spontaneous generation of new adipose tissue from an existing fat flap in rabbit is established. Tissue growth is spontaneous and needs no additional cells, growth or differentiation factors, or extracellular matrices.2. Survival of rabbit Autologous fat in tissue engineering chamber:Objective To observe if the exudation in tissue engineering chamber in the absence of blood vessels can support the survival of autologous fat graft. Methods Autologous fat was prepared as 1-3mm3 granular. immediately grafted to rabbits subcutaneous as control group; experimental group 1:immediately grafted into rabbit tissue engineering chamber; experimental group 2 :planted tissue engineering chamber to rabbits subcutaneous , and then grafted autologous fat after 20 days, Harvested after 3 months. Results The volume of grafted fat were reduced in all experimental groups .in control group and experimental group 1, the difference of adipose tissue volume has no statistically meaning. In experimental group 1 and group 2, the volume of adipose tissue were significantly different. Discussion The exudation in tissue engineering chamber can support the survival of some of the grafted fat, graft fat to issue engineering chamber delayed can improve the survival rate. Tissue engineering chamber can support the survival of part of high metabolic adipose tissue, with no growth factors, scaffolds, nutrients added.3. The research of exudation in tissue engineering chamberObjective To investigate the dynamic changes of exudation in tissue engineering chambers with different pore size on their walls, draw the time - volume curve; do some research on exudation, like dectect the amount of total protein, albumin, sugar and compared with the amount in serum; find out if the exudation contains transforming growth factor TGF-β. Methods Plant tissue engineering chamber in Rabbit dorsum, measure the volume of exudation in the tissue engineering chamber at specific time with syringe , trypan blue staining for dead cells at 7 days, 14 days, 21 days. Test total protein, albumin and sugar content in exudation with the serum as control. Take Western blot test for transforming growth factor TGF-β; harvest after 30 days. Results The volume of exudation in chamber gradually increased over time, with a stability at the volume of tissue engineering chamber. The dead cells was 97% in exudation. The amount of total protein, albumin, sugar is stable. The exudation contains a certain amount of transforming growth factor TGF-β, there is some coagulated exudates in chamber after 30 days. Discussion The inner environment in tissue engineering chamber is relatively stable, and the exudation has certain nutrients, but it can not support the survival of a single cell, coagulated exudates may play as scaffolds for tissue growth in chamber. 4. Xenograft fat induced de novo adipogenesis in rabbit tissue engineering chamber modelObjective To observe the survival of human fat graft in tissue engineering chamber model, whether there is immune rejection, or induce de novo adipogenesis in rabbit. To lay the foundation of making further use of in vivo tissue engineering chamber for tissue engineering adipose. Methods Plant four silicone tissue engineering chamber in the dorsum of each rabbit, 20 days later, make the subcutaneous fat tissue from human into pieces of 1-3mm3, and then graft into rabbit tissue engineering chamber, harvested after 3 months. Results Part of the human fat graft was survived. The capsule of tissue engineering was generated, the outer layer of capsule was highly vascularized, there are lots of prominent of fat tissue in the inner layer. the removal of the prominent cause small bleeding. Conclusion Xenograft fat induced de novo adipogenesis in rabbit tissue engineering chamber model.