Osteochondral tissue engineering based on biomimetic osteochondral scaffold contained calcified cartilage layer compounding with ADSCs in vivo / 中华骨科杂志

ABSTRACT

Objective The biomimetic osteochondral scaffold contained calcified cartilage layer(CCL) was fabricated using slik fibroin (SF) and hydroxyapatite (HA) for materials.To investigate effects of biomimetic osteochondral scaffold contained CCL compounding with ADSCs on regeneration of the osteochondral defect on the rabbit knee,explore the feasibility of this design as a concept of osteochondral tissue engineering.Methods We fabricated a novel biomimetic osteochondral scaffold with CCL using SF and HA by the combination of paraffin-sphere leaching and modified temperature gradient-guided thermal-induced phase separation (TIPS) technique.The pore size,porosity,and compressive modulus of elasticity of the scaffold cartilage layer and the osteogenic layer were measured by scanning electron microscopy and microscopy CT.The osteochondral defect model on rabbit bilateral knees were established,and implanted with the non-CCL group (non-CCL scaffold compounding with ADSCs) and CCL group (CCL scaffold compounding with ADSCs).At 4,8 and 12 weeks after implantation,the rabbits were euthanized,respectively.Gross observation score,histological and immunohistochemical assessment,biochemical quantitative of new osteochondral tissue,micro-CT scans for new bone,were executed.We evaluated the regeneration of osteochondral defects in each group,and verified the role of CCL in vivo.Results The biomimetic osteochondral scaffold with CCL had a consecutively overlapping trilayer structure with different densities and pore structures,including a chondral layer (top layer),intermediate layer and bony layer (bottom layer).The cartilage layer had a well-oriented microporous structure with a uniform distribution with a pore size of (112.43± 12.65)μm and a porosity of 90.25％±2.05％.The subchondral bone layer had a good three-dimensional macroporous structure,good connectivity,pore size (362.23±26.52) μm,porosity of osteogenic layer was 85.30％± 1.80％.The cartilage regeneration in CCL+AD-SCs group was better than non-CCL+ADSCs group.The content of GAG and type Ⅱ collagen in new cartilage tissue in CCL+AD-SCs group was much more than non-CCL+ADSCs group.The new bone tissue analysis and biomechanical testing had no significant differences between the two groups.Conclusion The biomimetic osteochondral SF/HA scaffold contained CCL mimics the structure of normal osteochondral tissue with good 3-dimensional pore structure and biocompatibility.The scaffold complex autologous ADSCs successfully repair osteochondral defects in rabbit knee,and the presence of CCL accelerates the growth of cartilage.