Renal tubular response to titanium dioxide nanoparticles exposure

Titatinum dioxide nanoparticles (TiO₂-NPs) are frequently used in several areas. Titanium alloys are employed in orthopedic and odontological surgery (such as hip, knee, and teeth implants). To evaluate the potential acute toxic effects of titanium pieces implantations and in other sources that allow the systemic delivery of titanium, parenteral routes of TiO₂-NPs administration should be taken into account. The present study evaluated the impact of subcutaneous administration of TiO₂-NPs on renal function and structure in rats. Animals were exposed to a dose of 50 mg/kg b.w., s.c. and sacrificed after 48 h. Titanium levels were detected in urine (135 ± 6 ηg/mL) and in renal tissue (502 ± 40 ηg/g) employing inductively coupled plasma mass spectrometry. An increase in alkaline phosphatase activity, total protein levels, and glucose concentrations was observed in urine from treated rats suggesting injury in proximal tubule cells. In parallel, histopathological studies showed tubular dilatation and cellular desquamation in these nephron segments. In summary, this study demonstrates that subcutaneous administration of TiO₂-NPs causes acute nephrotoxicity evidenced by functional and histological alterations in proximal tubule cells. This fact deserves to be mainly considered when humans are exposed directly or indirectly to TiO₂-NPs sources that cause the systemic delivery of titanium.