Methoxy Polyethylene Glycol Modification Promotes Adipogenesis In Xenogeneic Acellular Adipose Matrix

Background:Acellular adipose matrix(AAM)represents a promising scaffold for adipose tissue engineering.However,the unique and prolonged lipid removal process required for adipose tissue can damage extracellular matrix(ECM)bioactive components.We adopted a fast and mild decellularization to fabricate high-quality AAM(M-AAM),which realized better adipogenesis result than previous products.However,the remaining antigens in M-AAM remains to be a problem.Bioengineering of M-AAM by the covalent attachment of methoxy polyethylene glycol(mPEG)to remaining antigens provides a novel means to attenuate host immune reaction to mPEG-induced charge and steric camouflage.Previous studies demonstrated that immune camouflage effect by mPEG modification could decreased immune recognition both in vitro and in vivo.Few studies has been provided concerning the immune camouflage technique in AAM production.Objective:The adipogenesis results and regeneration mechanism of mPEG modified M-AAM were investigated.Methods:We first transplanted M-AAM in immune-deficient mice and wild-type mice to explore the impact of remaining antigens on the adipogenesis result of transplanted AAM.The adipogenesis results of mPEG-modified/unmodified M-AAM in wild-type mice were investigated.Then wild-type mice treated with CD28-SA antibody,anti-CD25 antibody and phosphate buffered solution were used as Treg cells up-regulation,Treg cells down regulation and control,respective.The relationship among mPEG modification,Treg cells level and M2 macrophages were verified by co-culture experiments in vitro.Methods in this study include histological staining,cell live/death staining,enzyme-linked immunosorbent assay,immunofluorescence staining,flow cytometry,quantitative real-time PCR,and Western blot assay.Result:1.Adipogenesis result and volume retention in immune-deficient mice was higher than in wild-type mice after M-AAM transplantation.2.mPEG modification could shield major histocompatibility antigen class I and? of M-AAM grafts,and reduced immunoglobulin M and immunoglobulin G levels in host circulation.3.mPEG-modified M-AAM could achieve better adipogenesis result and volume retention results after transplantation compared with the control.4.mPEG modification could improve Treg cells in M-AAM grafts.5.Treg cells secreted IL-10,IL-13 and TGF-?1 that promote the polarization of M2 macrophage,which improve the adipogenesis result in M-AAM transplantation.Conclusion:1.The remaining antigens in M-AAM limit the regeneration properties in vivo2.mPEG-modified M-AAM could achieve an excellent volume retention and adipogenesis results in vivo,and is a reliable biomaterial for soft tissue reconstruction in the future.3.Treg cells play an important role in xenogeneic M-AAM regeneration.