| Objective:To investigate the ability of repair of rabbit articular cartilage defects using a conjugated PEG gelatin. This biomaterial consists of HSNGLPL polypeptides which can self-assembling TGF-β and RGDS(Arg-Gly-Asp-Ser). Observe the influence of the different hybrid gel scaffolds on the chondrocytes regeneration and extracellular matrix generation of rabbit articular. To evaluate the advantages and disadvantages of different gelatin hybrid scaffolds as new biomaterials.Methods:A total of 50 healthy rabbits were selected randomly,4mm diameter, 3mm depth full—thick articular osteochondral defects were made in the center of the medial femoral condyle of the rabbits. These rabbits were randomly divided into 5 groups according to the scaffolds which will be filled in these defects:A group(void control group, untreated),B group(gelatin scaffold, only PEG gel), C group(gelatin-RGDS, gel contain RGDS), D group(gelatin-HSNGLPL, gel contain HSNGLPL polypeptides) and E group(gelatinHSNGLPL-RGDS, gel contain HSNGLPL polypeptides and RGDS). The repair of defects was periodically examined by gross observation,histology examination, micro-CT scan and analysis after the operation of 4 and 8 weeks respectively.Results:Gross appearance and histological stain show : after 4 weeks of the operation, there are obvious dent on the surface of articular defects in A,B and C group,the boundary is identified clearly between the new tissue and normal cartilage around the defects. The new tissue is composed mainly by fibrous tissue.Cells in the defects are small and have a long and narrow shape.Scarcely to see see hyaline-like chondrocyte. The new tissue filled the entire area of cartilage defects in D and E groups.The new tissue is white,tenacious and tramosericeous. The boundary is not easily to see compared with the others. The new tissue is composed mainly by hyaline-like cartilage, the new cells in the defects are smaller than the normal chondrocyte, and the cartilage lacunas are plenty.After 8 weeks of the operation, there were little dents on the surface of articular defects in A group,the new tissue is composed mainly by fibrous tissue.The surface of it is dark and coarse. In the deep lamella of the new tissues,we also can see some hyaline-like chondrocytes,the cells are small, the boundary still existed. The defects are filled by the new tissue in B and C groups.The surface is white and soft. Under the surface,there are some cartilage—like tissues, these cells are still small and slender, and the boundary can still to be seen. In D group the defects were almost as high as normal cartilage and filled by the hyaline-like cartilage.The boundary is difficult to discriminate.The dent on the surface of articular defects in E group disappeared totally.The new tissue is smooth and similar to that of the normal cartilage around the defects.The staining of the new tissue was as the same as that of normal cartilage around the defects. The boundary has vanished. Micro-CT scan shows: after 4 weeks of the operation, there are very clear dent on the surface of articular defects in A,B and C group. The new osteoid tissue filled the almost entire area of cartilage defects in D and E groups. There was no statistical difference between five groups according to BV/TV value. After 8 weeks of the operation, there were little dents on the surface of articular defects in A, B and C group, and have rugged surfaces of new born tissue. In D and E group the defects were almost as high as normal cartilage and the surface of new tissue is smooth.The curative effect of D and E group is more idealer than A, B and C group. And the efficacy of E group is the best in comparison with the other group according to BV/TV value and histological grading scores.Conclusion:1. The novel HSNGLPL- RGDS- conjugated PEG gelatin can supply ideal microenvironment for chondrocytes and have biodegradation, nontoxicity and good biocompatibility. And ti can fit for defects of any shape and depth, the application of it will be promising.2. The HSNGLPL-RGDS-conjugated PEG gelatin significantly accelerate the regeneration of chondrocytes in comparison with other groups in vivo.3. The RGDS- conjugated PEG gelatin slightly promote the regeneration of chondrocytes in comparison with PEG gelatin, and this indicate the physiological functions of RGDS have a effect on regeneration of chondrocytes via the cell attachment and focal adhesion.4. The HSNGLPL-conjugated PEG gelatin distinctly promote the regeneration of chondrocytes in comparison with the RGDS-conjugated PEG gelatin, and this indicate the physiological functions of HSNGLPL play a important role in the regeneration of chondrocytes in vivo. And this phenomenon is relate to function of self-assembling autologous TGF-β. |
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