The Experimental Study On The Repair Of Rabbit Degenerated Intervertebral Disc With Transplantation Of Bone Mesenchymal Stem Cells

Objective:To observe the bionomics of the bone marrow mesenchymal stem cells cultured in vitro;To prove the feasibility study that the animal mode of degenerative intervertebral disc was built by aspirating the nucleus pulposus through an posterolateral approach,to simulate human discectomy. To observe that if the MSCs grafted into the degeneratived intervertebral disc could survive and proliferate,and that if the MSCs could delay the disc degeneration and promote the disc repair .Methods:①.The rabbit bone marrow mesenchymal stem cells were isolated and purified with density gradient solution and attachment-independent culture system.To detect the surface antigens ,the labeled cells were analysed with a flow cytometer. The BMSCs were cultured in inductive serum-free medium containing transforming growth factor-β1 for two weeks,then examined by hematoxylin and eosin ,and immunohistochemistry.②.The animal mode of degenerative intervertebral disc was built by aspirating the nucleus pulposus through an posterolateral approach,then examined by MRI and hematoxylin and eosin at 2,4 and8 weeks after the operation,to detect degenerative disc.③.The MSCs were marked with BrdU in vitro, and grafted into the intervertebral disc.The specimens were stained with BrdU immunohistochemical methods.The mesenchymal stem cells (MSCs) from bone marrow were transplanted into a rabbit model of disc degeneration. Changes in disc height by plain radiograph, MRI and histology, were evaluated between controls group with PBS and MSCs-transplanted group.Results:①. MSCs have the capacity for self-renewal, proliferation, the multilineage potential to differentiate into chondrogenic lineages, and satisfy the characteristics of MSCs.So MSCs were the suitable seeding cells for intervertebral disc tissue engineering.The BMSCs ,analysed with a flow cytometer,expreesed positive CD44,but negative CD45.②.The animal mode of degenerative intervertebral disc was built,by aspirating the nucleus pulposus through an posterolateral approach,and examined by MRI and hematoxylin and eosin.③.The results showed that BrdU positive staining cells may be observed in the specimens at all the time after autografted.Results showed that after 12 weeks post-MSC transplantation, degenerated discs of MSCs-transplanted animals regained a disc height value of about 81.66±2.05%, On the other hand, sham-operated group discs demonstrated the disc height value of about 61.01±3.57%. Macroscopic and histological evaluations confirmed relatively preserved nucleus with structure in MSCs-transplanted discs . The histologic grading scores with MSC injection was statistically significant at the 4,8 and 12 week time points(P<0.05).Angiogenesis,osteophyte and cellular infiltration were not seen in the inner or middle layers of the anulus fibrosus or in the nucleus pulposus in any section of any group. Conclusions:1.Aspirating the nucleus pulposus from discs could induce lumbar intervertebral disc degeneration.2.It indicated that the MSCs grafted into the degeneratived intervertebral disc could survive and proliferate.The results suggest that MSC transplantation is effective in decelerating disc degeneration and repairing the degeneratived intervertebral discs in experimental models,and provided new hopes for treatment of degenerative disc disease in humans. BMSCs may serve as a valuable resource in cell transplantation therapy and tissue engineering repair for degenerative disc disease.