Gene-activated dermal equivalents to accelerate healing of diabetic chronic wounds by regulating inflammation and promoting angiogenesis

Diabetic chronic wound,characterized by prolonged inflammation and impaired angiogenesis,has become one of the most serious challenges in clinic and pose a significant healthcare burden worldwide.Although a great variety of wound dressings have been developed,few of encouraged achievements were obtained so far.In this study,the gene-activated strategy was applied to enhance sustained expression of vascular endothelial growth factor(VEGF)and achieve better healing outcomes by regulating inflammation and promoting angiogenesis.The gene-activated bilayer dermal equivalents(Ga-BDEs),which has good biocompatibility,were fabricated by loading the nano-sized complexes of Lipofectamine 2000/plasmid DNA-encoding VEGF into a collagen-chitosan scaffold/silicone membrane bilayer dermal equivalent.The DNA complexes were released in a sustained manner and showed the effective transfection capacities to up-regulate the expression of VEGF in vitro.To overcome cutaneous contraction of rodents and mimic the wound healing mechanisms of the human,a reformative rat model of full-thickness diabetic chronic wound was adopted.Under the treatment of Ga-BDEs,speeding wound healing was observed,which is accompanied by the accelerated infiltration and phenotype shift of macrophages and enhanced angiogenesis in early and late healing phases,respectively.These proved that Ga-BDEs possess the functions of immunomodulation and pro-angiogenesis simultaneously.Subsequently,the better regeneration outcomes,including deposition of oriented collagen and fast reepithelialization,were achieved.All these results indicated that,being different from traditional pro-angiogenic concept,the up-regulated expression of VEGF by Ga-BDEs in a sustained manner shows versatile potentials for promoting the healing of diabetic chronic wounds.

Gene-activated matrix harboring a miR20a-expressing plasmid promotes rat cranial bone augmentation

Gene-activated matrix(GAM)has a potential usefulness in bone engineering as an alternate strategy for the lasting release of osteogenic proteins but efficient methods to generate non-viral GAM remain to be established.In this study,we investigated whether an atelocollagen-based GAM containing naked-plasmid(p)DNAs encoding microRNA(miR)20a,which may promote osteogenesis in vivo via multiple pathways associated with the osteogenic differentiation of mesenchymal stem/progenitor cells(MSCs),facilitates rat cranial bone augmentation.First,we confirmed the osteoblastic differentiation functions of generated pDNA encoding miR20a(pmiR20a)in vitro,and its transfection regulated the expression of several of target genes,such as Bambi1 and PPARc,in rat bone marrow MSCs and induced the increased expression of BMP4.Then,when GAMs fabricated by mixing 100 ll of 2%bovine atelocollagen,20mg b-TCP granules and 0.5mg(3.3 lg/ll)AcGFP plasmid-vectors encoding miR20a were transplanted to rat cranial bone surface,the promoted vertical bone augmentation was clearly recognized up to 8 weeks after transplantation,as were upregulation of VEGFs and BMP4 expressions at the early stages of transplantation.Thus,GAM-based miR delivery may provide an alternative non-viral approach by improving transgene efficacy via a small sequence that can regulate the multiple pathways.

Recent advances in polymeric biomaterials-based gene delivery for cartilage repair

Untreated articular cartilage damage normally results in osteoarthritis and even disability that affects millions of people.However,both the existing surgical treatment and tissue engineering approaches are unable to regenerate the original structures of articular cartilage durably,and new strategies for integrative cartilage repair are needed.Gene therapy provides local production of therapeutic factors,especially guided by biomaterials can minimize the diffusion and loss of the genes or gene complexes,achieve accurate spatiotemporally release of gene products,thus provideing long-term treatment for cartilage repair.The widespread application of gene therapy requires the development of safe and effective gene delivery vectors and supportive gene-activated matrices.Among them,polymeric biomaterials are particularly attractive due to their tunable physiochemical properties,as well as excellent adaptive performance.This paper reviews the recent advances in polymeric biomaterial-guided gene delivery for cartilage repair,with an emphasis on the important role of polymeric biomaterials in delivery systems.