A superhydrophilic titanium implant functionalized by ozone gas modulates bone marrow cell and macrophage responses

Bone-forming cells and M phi play key roles in bone tissue repair. In this study, we prepared a superhydrophilic titanium implant functionalized by ozone gas to modulate osteoconductivity and inhibit inflammatory response towards titanium implants. After 24 h of ozone gas treatment, the water contact angle of the titanium surface became zero. XPS analysis revealed that hydroxyl groups were greatly increased, but carbon contaminants were largely decreased 24 h after ozone gas functionalization. Also, ozone gas functionalization did not alter titanium surface topography. Superhydrophilic titanium (O-3-Ti) largely increased the aspect ratio, size and perimeter of cells when compared with untreated titanium (unTi). In addition, O-3-Ti facilitated rat bone marrow derived MSCs differentiation and mineralization evidenced by greater ALP activity and bone-like nodule formation. Interestingly, O-3-Ti did not affect RAW264.7 M phi proliferation. However, naive RAW264.7 M phi cultured on unTi produced a two-fold larger amount of TNF alpha than that on O-3-Ti. Furthermore, O-3-Ti greatly mitigated proinflammatory cytokine production, including TNF alpha and IL-6 from LSP-stimulated RAW264.7 M phi. These results demonstrated that a superhydrophilic titanium prepared by simple ozone gas functionalization successfully increased MSCs proliferation and differentiation, and mitigated proinflammatory cytokine production from both naive and LPS-stimulated M phi. This superhydrophilic surface would be useful as an endosseous implantable biomaterials and as a biomaterial for implantation into other tissues.