RESUMO
Regenerating new tissue using cell transplantation has relied on successful cell engraftment in the host; however, cell engraftment into the diabetic skin wound is not as successful as in many other tissues. We used a biodegradable and biocompatible triblock co-polymer poly(ethylene glycol-b-[DL-lactic acid-co-glycolic acid]-b-ethylene glycol) (PEG-PLGA-PEG), which forms a thermosensitive hydrogel, as a wound dressing and scaffold. We found that the thermosensitive hydrogel increased the engraftment of muscle-derived stem cells (MDSCs) by 20- to 30-fold until day 20, when the wound was completely closed in a db/db genetically diabetic mouse model. At day 9, 30% of the transplanted MDSCs were found to remain, and 15% remained at day 20 after transplantation. The increased engraftment resulted in enhanced wound healing, as indicated by the wound closure rate, epithelium migration, and collagen deposition. Using MDSCs stably expressing beta-gal and immunofluorescence, we found that 25% of MDSCs differentiated into fibroblasts, 10% into myofibroblasts, and 10% into endothelial cells. We conclude that using the thermosensitive hydrogel as a scaffold increased the engraftment of MDSCs, which leads to improved diabetic wound healing, possibly by retaining the cells at the wound site for longer.
Assuntos
Diabetes Mellitus/cirurgia , Ácido Láctico/química , Polietilenoglicóis/química , Ácido Poliglicólico/química , Polímeros/química , Transplante de Células-Tronco/métodos , Animais , Diferenciação Celular , Células Cultivadas , Colágeno/metabolismo , Procedimentos Cirúrgicos Dermatológicos , Diabetes Mellitus/fisiopatologia , Feminino , Imunofluorescência , Hidrogéis , Camundongos , Camundongos Endogâmicos C57BL , Mioblastos/citologia , Mioblastos/transplante , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Pele/metabolismo , Pele/patologia , CicatrizaçãoRESUMO
PURPOSE: To accelerate diabetic wound healing with TGF-beta1 gene delivery system using a thermosensitive hydrogel made of a triblock copolymer, PEG-PLGA-PEG. METHODS: Two 7 x 7 mm full thickness excisional wounds were created in parallel at the back of each genetically diabetic mouse. The hydrogel containing plasmid TGF-beta1 was administered to the wound and formed an adhesive film in situ. Controls were either untreated or treated with the hydrogel without DNA. We used a commercial wound dressing, Humatrix, either with or without DNA, to compare the therapeutic effect with the thermosensitive hydrogel. RESULTS: We found that thermosensitive hydrogel alone is slightly beneficial for reepithealization at early stage of healing (day 1-5), but significantly accelerated repithelializaion, increased cell proliferation, and organized collagen were observed in the wound bed treated with thermosensitive hydrogel containing plasmid TGF-beta1. The accelerated reepithelialization was accompanied with enhanced collagen synthesis and more organized extracellular matrix deposition. Humatrix alone or with plasmid TGF-beta1, had little effect. CONCLUSIONS: Thermosensitive hydrogel made of PEG-PLGA-PEG triblock copolymer provides excellent wound dressing activity and delivers plasmid TGF-beta1 to promote wound healing in a diabetic mouse model.
Assuntos
Complicações do Diabetes , Diabetes Mellitus/genética , Técnicas de Transferência de Genes , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/uso terapêutico , Cicatrização/efeitos dos fármacos , Cicatrização/genética , Animais , Antimetabólitos , Bromodesoxiuridina , Divisão Celular/efeitos dos fármacos , DNA/administração & dosagem , DNA/química , Feminino , Temperatura Alta , Humanos , Hidrogéis , Insulina/sangue , Ácido Láctico , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Veículos Farmacêuticos , Plasmídeos/genética , Polietilenoglicóis , Ácido Poliglicólico , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Polímeros , Proteínas Recombinantes/farmacologia , Pele/patologiaRESUMO
PURPOSE: Currently, most pDNA delivery systems based on synthetic polymers are either nonbiodegradable or not sensitive to the release environment. The primary objective of this study was to develop and evaluate an aqueous-based, thermosensitive, biodegradable and biocompatible triblock copolymer to control pDNA delivery in vitro and in vivo. METHODS: The triblock copolymers, poly[ethylene glycol-b-(D, L-lactic acid-co-glycol acid)-b-ethylene glycol] (PEG-PLGA-PEG), were synthesized as previously described. The molecular weight and polydispersity of PEG-PLGA-PEG were monitored by gel permeation chromatography (GPC). The cytotoxicity of PEG-PLGA-PEG was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The release of 32P-labeled pDNA entrapped in aqueous dispersion of PEG-PLGA-PEG in 0.1 mol/L sodium phosphate buffer solution (pH 7.4) was studied at 37 degrees C under agitation. Gene transfection efficiency was evaluated in a skin wound model in CD-1 mice. RESULTS: The aqueous dispersion of PEG-PLGA-PEG flows freely at room temperature but form a gel at 37 degrees C body temperature. The in vitro degradation of PEG-PLGA-PEG lasted for more than 30 days. The cytotoxicity of PEG-PLGA-PEG evaluated in HEK 293 cells was significantly lower than that of poly-L-lysine hydrochloride. The release profile of supercoiled pDNA from the polymer followed the zero-order kinetics up to 12 days. Maximal gene expression of luciferase was at 24 h in the skin wound of CD-1 mice and by 72 h, the expression dropped by nearly 94%. CONCLUSION: These results suggest hydrogel formed by PEG-PLGA-PEG could be a promising platform for delivery of pDNA, which represents a novel strategy that may serve as a non-viral vector for gene therapy in wound healing.