| Objective The purposes of this study were to investigate the mesenchymal stem cells(MSCs) affected by microenvironment of cartilage and to research the features and biocompatibility of porous Poly(vinyl alcohol) (PVA)and its composite. In addition,we wanted to preliminary observed the repairing results of knee osteochondral defects in the rabbit by using new porous integrative interlocked biomaterial, Polyamide 66/nano-Hydroxyapatite(PA66/n-HA) and Poly(vinylalcohol)/Gelatin(PVA/Gel) composite.Methods①Chondrocyte of rabbit and its disused culture medium were used to simulate the cartilaginous microenvironment. We observed the effect cocultue chondrocyte or its disused cultue medium with MSCs on cartilaginous phenotype in vitro by microscope observation, toluidine blue staining and in situ hybridization for type II collagen mRNA.②Porous PVA , PVA/n-HA,PVA/Gel,Poly(vinyl alcohol)/Chitosan(PVA/Cs) materials were prepared by emusifier-foaming, freeze-drying and surfactant-cleaning method. The features and biocompatibility of above materials were further studyed by image analysis,mechanics test,MTT,ELISA assay,cocultue with MSCs and muscle implanting and so on.③prepared new porous integrative interlocked PVA/PA66/n-HA or PVA/n-HA/PA66/n-HA biomaterials,which upper layer material is PVA or PVA/n-HA and underlayer is PA66/n-HA. We evaluated their mechanics feature and the effects of repairing knee joint osteochondral defect of rabbits.④PA66/n-HA scaffold,which was seeded with MSCs in vitro,was implanted to knee joint osteochondral defect of rabbits.At the same time, the scaffold was lower than normal cartilage a little. After 1 and 4 months,we investigate the repairing effects.⑤We have also explored repairing effects of knee joint osteochondral defect of rabbits by implanting porous PVA/Gel,which was prepare by Tween-20 foaming agent.Differented to above method, MSCs were injected to PVA/Gel after materials implanting to defect 2 weeks.Results①Cocultue chondrocyte with MSCs would affect each other.Perhaps the 2:1 ratio of MSCs and chondrocytes was beneficial to maintenance cartilaginous matrix and increasing collagen II mRNA expression. The disused culture medium of chondrocytes could also induce MSCs to chondrocyte-like change and express collagen II mRNA,but the cells appeared hypertrophic.②The materials obtained by this method had high hydrophilicity,porosity,pore interconnectivity and proper elasticity. Scanning electron microscopy (SEM) showed that the material had a lot of micropores (less than 10 urn) on the walls of macropores (100～300μm). Porous PVA,PVA/n-HA and PVA/Gel had relative better biocompatibility,compared with control materials. PVA/Gel and PVA/Cs had better cellular compatibility with MSCs,but the latter had bigger inflammatory reaction when muscle implanting.③PVA/n-HA/PA66/n-HA had better repairing effects of knee joint osteochondral defect of rabbits.Underlayer material was stable.④PA66/n-HA scaffold,which was seeded with MSCs , had better repairing effects of knee joint osteochondral defect of rabbits.After 4 months,repaired cartilage main expressed collagen II ,also expressed collagen I .⑤The PVA/Gel obtained by this method also had good porosity(76%),pore interconnectivity. Scanning electron microscopy (SEM) showed that the material had micropores and macropores. Afer 4 months, porous PVA/Gel,which was injected MSCs,had a satisfactory repairing results.But the stability of material was not enough.Conclusion Our study suggests that microenvironment of cartilage,to some extent,can indue or maintain cartilaginous phenotype in vitro. So,our data provide clues to induce MSCs differentiation to cartilaginous direction.PA66/n-HA plays a key role in keeping instantly long-term stability of materials.Porous PVA/Gel is a better material for cartilage repairing.In the future, seeking for new methods such as surface modification ,adding other materials or preparing degradation PVA are required.
|
PDF Full Text Request