Mesenchymal Stem Cells Engineered With A Co-delivery System Loaded With SOX9 Plasmid DNA/BMP7 And Cartilage-targeted Peptides For Osteoarthritis Therapy

Objectives:Osteoarthritis(OA),characterized by the degradation of articular cartilage,is a total joint disease with no effective curative drugs.Currently,delaying cartilage degradation and repairing damaged cartilage are regarded as the key strategies for OA treatment.Mesenchymal stem cells(MSCs),with abundant sources,are the promising choice for tissue repairment.There are lots of clinical trials demonstrating MSCs can relieve the pain symptom,but revealing the limited repairing effect on OA cartilage,which may be due to possibly unexpected differentiation.Thus,it would have a great significance to examine how MSCs differentiate to chondrocytes more effectively and then to be hyaline cartilage accurately.Methods:In order to enhance the chondrogenic capacity of MSCs and inhibit the hypertrophy effect during differentiation,we built a copper-based system loading SOX9 plasmid DNA and BMP7 recombinant protein that was used to remold MSCs via engineering strategies.In addition,cartilagetargeted peptides were modified on the cell surface by chemical click reaction,leading more MSCs to gather on the cartilage.In vitro,we verified the effect of chondrogenesis by testing the expression of gene(eg.COL2,ACAN,SOX6,SOX9),protein(eg.COL2,SOX9)and glycosaminoglycan after 7,14,28 days for inducing on MSCs.Meanwhile,we tested the expression of MMP13 and COL-X for estimating anti-hypertrophy effect Moreover,we examined the function of targeted-peptide via IVIS and OA explant experiment.In vivo,we established an OA model with DMM in mice with different engineered MSCs administration into articular cavity.After 8 weeks,we evaluated the repair effect via some methods including SO-FG,IHC,IF.Results:A co-delivery system(CSB)was successfully synthesized,delivering SOX9 plasmid and BMP7 into MSCs for engineering(termed CSB-MSC).In vitro,we found that engineered MSCs expressed more chondrogenic genes and proteins including COL2,ACAN,SOX6 and SOX9 compared to the purified MSCs while hypertrophy indicator including MMP13 and COL-X in CSB-MSC were downregulated.Moreover,we modified the MSCs with cartilage-targeted peptides(termed W-MSC)and found that compared with MSCs,more W-MSC stayed in knee for a longer time.In vivo,after intraarticular administration in mice with DMM,engineered MSCs with targeted peptides(termed W-CSB-MSC)showed an effective effect on cartilage repairment with PBS group as the control group.Besides,we found that W-CSB-MSC also exhibited a satisfying effect on repairing OA cartilage explant from human.Conclusions:In summary,we developed a co-delivery system(CSB)for engineering MSCs.This system could promote MSCs differentiate to chondrocytes more effectively and inhibit hypertrophy especially at the late stage.After engineering,MSCs not only gained more effective chondrogenesis with lower risks of hypertrophic cartilage but also gathered on cartilage for a longer time after modifying of cartilage-targeted peptides,which made contribution to OA cartilage repairment.Hence,this study provided a hopeful option for OA therapy to inject MSCs by a nanoengineered way.