A Bioinspired Wound Dressing Loaded With Micronized Amnion For Scarless Skin Regeneration

Objective: According to reports,burn injuries and chronic wounds affect more than 11 million and 6.5 million people every year,respectively.Large areas of skin wounds or burns are often faced with scars after treatment.Many wound dressing materials have emerged in the past decades to improve skin repair,such as against at infection and inflammation,deliver biologically active substances to promote repair.Nevertheless,the general successful outcomes that has been reported are accelerated wound closure,seldom involving skin appendages regeneration.Cell treatment seems another good choice,but it usually takes several weeks to culture and amplify cells tailored for each patient,whose cost are highly.Amnion constitutes a pre-formed stem cell sheet,which is rich in stem cell resources,but it is relatively soft and thin,making it difficult to attach to the wound bed.Therefore,our research team developed the skin secretion of Andrias davidianus(SSAD)hydrogel as a scaffold material for micronized amnion(about 600 μm)to jointly promote the scarless healing of large skin defects and explore its possible mechanism for promoting scarless healing.Methods: After a certain process,the research group processed the amnion and the skin secretions of Andrias davidianu(SSAD),and obtained SSAD powder and micronized amnion(about 600 μm).The obtained SSAD powder was mixed with PBS to form SSAD hydrogels with adhesive property.The bonding interface between the SSAD hydrogel and the amnion was observed by scanning electron microscopy.In vitro,live and dead cell staining and TUNEL staining of micronized amnion tested the toxic effect of SSAD hydrogel on micronized amnion.Through cell proliferation experiments,scratch and transwell assays of amniotic mesenchymal cells and Ha Cat cells were performed to examine the influence of SSAD hydrogel on cell migration and proliferation.A model of a complete layer skin defect with a diameter of 20 mm on the back of a rat was created.The micronized amnion and SSAD hydrogel were used as the positive control group,and the wound bed alone was used as the negative control group.Evaluation of the SSAD hydrogel as the carrier for micronizd amnion to promote scarless skin healing.At the same time,it was tested whether the SSAD hydrogel as a carrier for micronized amnion has toxic and side effects on experimental animals.Finally,through transcriptome analysis of Ha Cat cells cultured in SSAD-conditioned medium and 4 groups of experimental animals,the possible mechanism of SSAD hydrogel as a carrier for micronized amnion was analyzed.Result: SSAD hydrogel formed a good adhesion interface with micronized amnion.SSAD hydrogel have showed good biocompatibility.In vitro micronized amnion showed less apoptosis than the control group with staining of living / dead cells and the TUNEL test.Cell proliferation,scratches and Transwell assays revealed that SSAD hydrogel could promote the proliferation and migration of amniotic mesenchymal stem cells and Ha Cat cells.In addition,the results of the skin defect rats showed that the wound healing time of the SSAD hydrogel as the carrier for micronized amnion group was the shortest,and the regenerated tissue could achieve skin healing scarless,with the regeneration of skin appendages.At the same time,the toxicity test showed that there was no organ damage and necrosis in the rats of each group.Transcriptome analysis showed that SSAD has positive regulation effects on cell migration,differentiation and proliferation,which may be attributed to the abundant growth factors in SSAD.Conclusion: The hydrogel derived from the the skin secretion of Andrias davidianus has good adhesion and biocompatibility,and can be used as a scaffold material to load the micronized amnion to promote skin healing scarless.Meanwhile,its potential to promote cell migration,differentiation and proliferation shows that it has a wide range of medical application value.