How bone marrow-derived human mesenchymal stem cells respond to poorly crystalline apatite coated orthopedic and dental titanium implants

Due to the delayed and weak bone-implant integration in dental and orthopedic devices, there have been several attempts to enhance implant-bone interactions for rapid osseointegration. In this paper, the interactions of human bone marrow-derived stromal (mesenchymal) stem cells (hMSCs) with uncoated and coated titanium alloy implants with poorly crystalline apatite are studied. First the configuration and chemical composition of the apatite coatings and their deposition progress in different experimental conditions are investigated and discussed. Then, hMSCs are cultured on different substrates and cell attachment and proliferation are monitored and evaluated for different time intervals. Although the uncoated and coated substrates indicate good cell attachment, the differences in proliferation and morphology of the cells spread over the coated samples are significant. It is concluded that the coated samples improve the capability for accepting the cells in three-dimensional and slender shapes. The migration of hMSCs on both substrates are discussed. As such cell migration is directly associated to the osteoconduction, the findings confirm the hypothesis of enhancement in bone formation on the surface of biomimetically poorly crystalline apatite coated titanium implants. This in vitro study demonstrates that the coated samples are nontoxic and biocompatible enough for ongoing osteogenic studies in bone or dental defects in animal models in vivo.