Micro-fragmented Adipose Tissue-based Natural Stem Cell Scaffold For Regeneration Of Cartilage Defect

Articular cartilage is a kind of tissue with special structure covering the surface of joint,mainly composed of cartilage matrix and chondrocytes.Once damage occurs,cartilage hardly self-regenerates and self-repairs due to the reason that there is no blood vessels and nerve.In recent years,the development of stem cell-based therapy in the field of regenerative medicine has provided a new strategy for cartilage regeneration.Adipose-derived mesenchymal stem cells(ASCs)are widely used in regeneration studies because of their advantages such as rich sources,low invasiveness,easy access,and multi-directional differentiation potential.However,the in vitro culture expansion process will cause cell senescence and reduce the differentiation potential of ASCs.At the same time,traditional enzymatic digestion will destroy the surface structure of ASCs and affect cell viability.Exogenous collagenase may also spread diseases.Therefore,we use purely physical and mechanical methods to treat adipose tissue in order to obtain a natural scaffold containing rich and highly active ASCs for the repair of cartilage defects in vivo and to evaluate its regenerative efficacy.Lipogems?is a new,closed device that uses magnetic beads to emulsify adipose tissue,reduce the size of fat clusters,and remove residual inflammatory oils and blood to obtain micro-fragmented adipose tissue(MFAT).It was determined that the cells cultured from MFAT were mainly ASCs by flow cytometry technology,and their multi-directional differentiation potential was verified by adipogenic,chondrogenic and osteogenic differentiation.The effects of MFAT on the migration of chondrocytes were studied by scratch and migration experiments in vitro.Finally,it was determined whether MFAT could promote the regeneration of cartilage defects in vivo through key elements such as natural scaffolds(adipose tissue structure),cellular components(ASCs)and growth factors(secreted cytokines and chemokines).Our results demonstrated that abundant ASCs with multi-directional differentiation potential was contained in MFAT,while MFAT could significantly enhance chondrocyte migration.Animal experiments showed that the MFAT treatment group had better cartilage repair effect than the PBS treatment group after 6 and 12 weeks of treatment.At 12 weeks after operation,the cartilage surface of the MFAT treatment group was smooth and flat with higher expression of hyaline cartilage.Meanwhile,the reconstruction of inferior bone was intact and the expression of type Ⅰ,Ⅱ and Ⅵ collagen was compatible with normal cartilage.Our research findings proved that the MFAT obtained by using purely mechanical method was useful for cartilage regeneration.And it can be a safe and promising alternative to traditional cell therapy for cartilage defect repair.