NEUROPEPTIDES IN HETEROTOPIC BONE INDUCED BY BONE-MATRIX IN IMMUNOSUPPRESSED RATS

The effects of cyclosporin A on the occurrence of neuroendocrine pepti des in bone induced by demineralized allogeneic and xenogeneic bone ma trix were studied in rats, Cyclosporin A enhanced bone induction in de mineralized allogeneic bone matrix implants by 40% to 50% at 4 weeks, whereas there was no difference to the control group at 8 weeks, In de mineralized xenogeneic bone matrix implants there was virtually no car tilage or bone formation at 4 weeks, but some bone and cartilage forma tion was seen at 8 weeks, In both cyclosporin A treated groups the net bone formation in demineralized xenogeneic bone matrix implants was i ncreased four to five times at 4 weeks, Cyclosporin A treatment did no t alter the temporal occurrence or distribution of neuropeptide contai ning nerve fibers in the bone induced by allogeneic bone matrix, Fiber s containing substance P, calcitonin gene related peptide, neuropeptid e Y, vasoactive intestinal peptide, and tyrosine hydroxylase were dete cted in the ossicles of cyclosporin A treated and control rats, In the xenogeneic bone matrix of the control group, no immunoreactive nerve fibers could be detected at 4 weeks, but at 8 weeks all five neuropept ides were detected, However, after cyclosporin A treatment immunoreact ive nerve fibers could be seen at 4 weeks in the demineralized xenogen eic bone matrix implants, Thus, immunologic properties of the inductiv e matrix affect the yield of mineralized bone and the degree of innerv ation, Cyclosporin A decreases the immune response and enhances the fo rmation of bone and the number of transmitter identified nerves in dem ineralized xenogeneic bone matrix induced ossicles.