Study On Cultured RMSCs Proliferation And Osteogenesis Differentiation Affected By Titanium Particles Loading

Total joint replacement is an efficacious, reliable, and cost-effective procedure for treatment of joint affricated by end-stage arthritis or osteoarthrosis since its advance more than thirty years ago. With improvement in fatigue strength of the prosthesis, and skeletal fixation, wear debris and its seqelae have become the primary limitation of total joint replacement longevity. The particle-induced activation of monocytes/macrophages and bone resorption adjacent to a prosthesis has been extensively studied, but only limited information is available on the response of MSCs to paniculate wear debris and the inhibition in bone formation around a prosthesis, periprosthetic normal maintenance of net bone relies on the well balanced coordination of the bone formation and bone resorption. For this reason, it is necessary to study the effect of paniculate wear debris of Titanium particles on cells proliferation.diffentiation, osteoblastic phenotype expression, maintenance at the bone formation site for further understanding the pathoenesis mechanism of artificial joint prosthetic aseptic loosening in later stage.Through density-gradient centrifugation isolation and percoll isolation subculture attachment selection, the rMSCs culture became much purified. TEM and SEM observation showed the fibroblastic appearance and the fast growth characteristic of MSCs, and Flow cytometer analysis that CD44 present positive and CD45 present negative. Those evidence prove that the mesenchymal stem cellscultured have multipotential stem cell nature in our laboratory.MTT-assay and Confocal Laser Scanning Microscopy are utilized to detect rMSCs proliferation rate and morphologic variety. In vitro studies showed Titanium particles loading can suppress the proliferation of osteogenesis behavior of MSCs, but this down-regulation is various in different circle diameter, varied concentration and various loading durations of Ti particles.The osteogenic induction compound had strong effect on promoting proliferation. To test the cultured rMSCs' osteogenisis potentiality by Titanium particles loading, we measured the changes of alkaline phosphatase(ALP) activity, the modulations of osteocalcin (OCN) protein procuction and collagen I (COLL I) protein production and formation of calcium deposites. Our results showed that the cultured rMSCs could be induced to osteoblasts, which was testified by, under osteogenic induction condition, the increases of ALP activity and OCN protein and COLL I protein production, as well as the formation of calcified bone nodules. Titanium particles loading can depress ALP activity and OCN protein and COLL I protein production, but this down-regulation is various in different circle diameter, varied concentration and various loading durations of Ti particles.