BIOLOGICAL RECONSTRUCTION OF PERIODONTAL TISSUE USING CYTOKINE AND FIBROUS COLLAGEN MEMBRANE

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Bone morphogenetic protein (BMP) is a growth and differntiation factor that stimulates immature mesemchymal cells to create a process similar to endochonral ossification when it is implanted with insoluble bone matrix (IBM) as a carrier. Roles of this carrier is still unkown and carriers other than IBM have not been investigated. We have deviced a fibrous collagen membrane (FCM), in order to combine it with BMP and to implant subcutanuously for ectopic bone formation. In this research project, first we succeeded in generating the ectopic formation of bone and cartilage independently in FCM/BMP implant. Thus, in order to clarify the mechanism behind the phenomenon of carrier-dependent pehonotype expression by BMP, we prepared and deviced at least six different types of carriers, combined them with the chromatographically-purified BMP, and compared the phenotype expression upon implantation. New BMP-carriers other than IBM and FCM included the porous particles of hydroxyapatite (PPHAP), solid particles of hydroxyapatite (SPHAP), honeycomb shaped hydroxyapatite and fibrous glass membrane (fine and coarse FGM). Most striking finding was that the coarse FGM/BMP induced only cartilage inside the membrane, while the PPHAP/BMP induced only bone within the pore of the PPHAP.It was found that SPHAP/BMP and the fine FGM/BMP did not induce bone nor cartilage at all. Honeycomb HAP, which is consistedof cylindrical blocks (1.4 x 0.7 mm) with seven tubular holes of 0.12 mmdiameter, induced very unique shape of bone, generating the columnar bone in the center of each tubular hole, not on the inner surface of tubular holes. It was interpreted that pores in the PPHAP provided the space for vasculature which was feasible for direct bone formation, while FGM rejected vasculature but permitted mesenchymal cells entering into the membrane, which provided a feasible circumstances for cartilage formation. Above results indicate that geometrical factors are important in the use of FCM and