An Injectable Dextran-Gelatin Hydrogel Scaffold Combined With Cytokines For Cartilage Tissue Engineering

Part1:The exploration of a novel injectable dextran-gelatin hydrogel scaffoldObjective:To explore the compatibility between the novel injectable dextran-gelatin hydrogel scaffold and synovium-derived mesenchymal stem cells (SMSCs).Methods:The SMSCs were obtained with passage isolation. The novel injectable dextran-gelatin hydrogel scaffold was fabricated from oxidized dextran (Odex) with modified gelatin. The dynamic gelling process was measured through rheological measurements. The effect of the ratio of Odex and gelatin on gelling time, microstructure, swelling ratio and in vitro degradation of the composite hydrogels were examined. Biological assess was performed through WST-1Assay by using synovium-derived mesenchymal cells (SMSCs).Results:Passage isolation shows flat, large, spindle-shaped or stellate-shaped cells. Adjustable physic-chemical properties can be obtained through simply altering the ratio of oxidized dextran and modified gelatin. For the oxidized dextran/modified gelatin (ratio5:5) system, tgel was approximately95s, which was very fast during hydrogel formation. All hydrogels showed good interconnected porous structures with an average pore sizes ranging from50-200μm. Moreover, with the increase of incorporated gelatin, better biocompatibility was showed in the composite hydrogels.Conclusion:The novel injectable dextran-gelatin hydrogel scaffold has a good cytocompatibility, which exhibited its potentially high application prospect in the field of cartilage tissue engineering. Part2:The experimental study on migration of synovium-derived mesenchymal stem cells by five chemotactic factorsObjective:To explore the chemotactic migration effects of serum, TGF-β3, PDGF-AB, BMP-2, and FGF-basic on rabbit synovium-derived mesenchymal stem cells (SMSCs).Methods:The SMSCs were obtained with passage isolation, and then stimulated by low-glucose DEME containing TGF-β3, PDGF-AB, BMP-2, FGF-basic with50ng/ml concentration as well as0.1%,0.5%,1.0%,2.0%,5.0%,10.0%,20.0%serum. The migration of SMSCs under five different chemotactic factors was observed in Transwell chamber assays.Results:TGF-β3, PDGF-AB, BMP-2, FGF-basic and serum consistently enhanced the migration activity of rabbit SMSCs. Compared with other concentration,5.0%is the appropriate concentration for serum to induce the migration of rabbit SMSCs. Among the four growth factors, PDGF-AB showed more potent chemotactic effect than other three.Conclusion:The migration of SMSCs from rabbit could be enhanced by TGF-β3, PDGF-AB, BMP-2and FGF-basic. PDGF-AB is the most potent chemotactic factor among the four growth factors, and may be useful to promote cell homing and cartilage regeneration in situ during cartilage repair. Part3:The experimental study on the effects of chondrogenesis by four cytokinesObjective: To investigate and compare the effects of TGF-β3, PDGF-AB, BMP-2, and FGF-basic dextran-gelatin hydrogel scaffolds combined with SMSCs on the chondrogenesis in vivo.Methods:The SMSCs were seeded into dextran-gelatin hydrogel scaffolds. Five groups were injected subcutaneously in the dorsum of nude mice. TGF-β3group:TGF-β3dextran-gelatin hydrogel scaffolds combined with SMSCs; PDGF-AB group:PDGF-AB dextran-gelatin hydrogel scaffolds combined with SMSCs; BMP-2group:BMP-2dextran-gelatin hydrogel scaffolds combined with SMSCs; FGF-basic group:FGF-basic dextran-gelatin hydrogel scaffolds combined with SMSCs; control group: dextran-gelatin hydrogel scaffolds combined with SMSCs. Samples were harvested at8weeks after operation. Hematoxylin-eosin and toluidine blue staining were done for the cross-section of the samples.Results:Gross view of TGF-β3, PDGF-AB, BMP-2, FGF-basic samples were cartilage-like and white when harvested at8weeks after operation. Hematoxylin-eosin and toluidine blue staining showed that a homogenous cell distribution and abundant cartilage-like extracellular cell matrix formation were achieved in TGF-β3group, BMP-2group and FGF-basic group when compared with control group and PDGF-AB group.Conclusion:Excellent biocompatibility was shown in the dextran-gelatin hydrogel scaffolds after being injected in nude mice. TGF-β3, BMP-2, and FGF-basic enhanced the chondrogenesis in vivo compared to PDGF-AB. No significant difference was observed between the effects of chondrogenesis by PDGF-AB or without cytokines.