The Investigation Of The Early Cell Differentiation And The Phenotype Expression Of Specific Proteins In The Osteoinduction Of Calcium Phosphate Ceramics

In current study, the cell differentiation, the mineralization of the new bone matrix, the ultrastructure between HA/ P-TCP cermics and new bone, and the phenotype expression of specific proteins, including collagen type I and bone sialopritein, in the osteoinduction of HA/ P-TCP ceramics have been investigated via Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Raman Spectra, Scanning Electron Microscopy (SEM), Immunohistochemistry (IHC) staining and histological methold respectively. The new evidences to prove the osteoinduction of HA/ p-TCP ceramics have been obtained based on the outcomes of experiments mentioned above. Meanwhile, the expression of Bone Morphogenetic Proteins (BMP-2 and BMP-4) and the receptor of BMP-2 (BMPR2) were performed via IHC. The present results have demonstrated that the native BMPs and their receptors were expressed in the newly-formed tissue in the osteoinduction of HA/ p-TCP ceramics, which indicated the native BMPs and their receptors may act as important roles in osteoinduction.TEM observation showed that croweded active cells with abundant endoplasmic meticulum (ER) synthesizing and sorting proteins, which originated from sheetlike mesenchymal cells lining the outer and inner of in-growth capillary. The studies of mineralization on the newly-formed bone matrix and the ultrastructure of the interface between HA/ P-TCP ceramics and newly-formed tissue to confirmed that new precipitation biological apatite was epitaxic growth on the surface of HA/ P-TCP ceramics and was less crystallnity, non-stoichment and other ions substituted, such as Na, K and S. It gives us new evidence for osteoinductivity of Ca-P ceramics from the inorganic component of bone tissue.XRD pattern of implants before and after implanted confirmed that P-TCPphase has been reduced due to the dissolving of P-TCP in vivo with time. Raman Spectra have demonstrated that some proteins have been adsorbed on surface of HA/ P-TCP, including matrix fibronectin, an important protein for adhesion of cells.The results of IHC have demonstrated that the expression of Collagen type I and bone sialoprotein in the new-formed tissue in HA/ P-TCP ceramics implanted in non-osseous sites temporarily and spatially. It demonstrated the osteoindutivity of HA/ P-TCP ceramics not only based on the morphology of tissue but also on the phenotype expression of specific proteins. It also confirmed this osteoinduction is the normal bone formation processes.The investigations of the expression of BMPs via IHC have demonstrated that BMP-2 has been expressed in the extracelluar matrix (ECM) near HA/ p-TCP ceramic surface and tube-like tissue before osteogenesis. Meanwhile, there were some cells with irrugulated shapes have expressed BMPR2, which indicted the existence of target cells. BMP-2 and BMP-4 were also expressed after implanted 60days in the new-formed tissue. The present results have inferred that various native BMPs may play varied roles in osteoinduction of HA/ P-TCP ceramics.