Accerlation Of Cartilage Tissue Repair In Rabbit By Gelatin Methacryloyl (GelMA) Hydrogel With TGF-?1 Auto-recruitment

Objective:Todevelop a kind of Gelatin methacryloyl(GelMA)hydrogel scaffolds which can auto-combine with endogenous transforming growth factor-beta 1(TGF-?1)and to investigate the effect for chondrogenesis of human mesenchymal stem cell in vitro and repair of full-thickness cartilage defect in rabbit.Methods:(1)Preparation of GelMA and GelMA / HSNGLPL peptide hydrogel scaffolds.(2)Characterizing physical properties of the scaffolds,such as of surfacecharacters,fluid properties and expansion characters.Measuring the biocompatibility of the scaffoldsby CCK-8 and LIVE/DEAD staining,respectively.In vitro,mesenchymal stem cells(MSCs)was induced into chondrocytes on the cell culture plate or hydrogel scaffolds preincubated with TGF-?1.3 days later,cartilage-related gene expressions were assayed by quantitative PCR(q-PCR);7 day later,red O fast green dyeing was carried out to determine the distribution of collage type II and GAGs.(3)In vivo,rabbits were divided into four groups: sham operation group(group A),model group(group B),GelMA group(group C)and GelMA/HSNGLPL(group D).Knee full-thickness cartilage defect in rabbitswas set and treated with or without GelMA or GelMA/HSNGLPLhydrogel.Gross study,Micro-CT,H&E,toluidine blue staining and type II collage immunohistochemical staining were carried out to evaluate the effect of biological scaffold on the cartilage defect repair at 4 and 8 week post-operation,Results:(1)GelMA and GelMA/HSNGLPLhydrogel scaffolds were successfully prepared.Superficial study and SEM image suggested that the hydrogel scaffolds had similar characteristics.(2)Rheometer to determine fluid property,indicating that HSNGLPL attaching to GelMA did not affect its storage modulus and loss modulus.The results of CCK-8 showed that GelMA and GelMA/HSNGLPL can be effectively for cell attachment and proliferation.Moreover,MSCs inoculated on scaffolds for 5 days,LIVE/DEAD stainingproved that the GelMA and GelMA/HSNGLPL hydrogel scaffolds have good biocompatibility.In order to testified GelMA/HSNGLPL be able to recruitTGF-?1,we compared the cartilage-related gene expressions,the results showed the degree of up-regulated of sox-9,col II,agg,col1,col10 gene expression in the GelMA/HSNGLPL was higher than those in other groups;Red O fast green dyeing showed intense staining of GAG and COL IIin GelMA/HSNGLPL which is consistent with result of gene expression.In vitro studies indicated that GelMA/HSNGLPL could combined with TGF-?1 and keep its biological activity.(3)In vivo study,more cambium and smooth surface were observed at the injury knee joint of rabbit treated with GelMA/ HSNGLPLhydrogel scaffold than those of other groups,with a visible margin.BV/TV value and histological evaluation have also demonstrated higher score in GelMA/ HSNGLPL-treated knees than other groups at 4 and 8weeks post-surgery.More cartilage-like tissue including GAG and COL IIwere also displayed.All the date further are suggestive of GelMA/HSNGLPLhydrogel scaffoldaccelerating cartilage tissue repair in rabbit.Conclusions: GelMA/HSNGLPL hydrogel scaffoldhas great mechanical properties andbiocompatibility,and it can promote the differentiation of MSCs into cartilage in vitro and the cartilage defect repaired in vivo by means of recruiting TGF-?1,which provides a promising system for cartilage repair in clinical application.