67. 3D-printed porous biomimetic titanium promotes osteogenic gene expression in murine mesenchymal stem cells

Abstract

BACKGROUND CONTEXT Titanium is a commonly used implant material in orthopedics due to its biocompatibility with bone. Nonetheless, bone resorption caused by stress shielding is a concern. It has been reported that 3D-printing can be used to impart porosity that mimics the structure of trabecular bone, which could create a more osteogenic environment. PURPOSE In this study, we compared the capabilities of smooth titanium (TS), polyether-ether-ketone (PEEK), and 3D-printed titanium (T3) to promote expression of bone-relevant genes. STUDY DESIGN/SETTING In vitro cell culture study. PATIENT SAMPLE Not applicable. OUTCOME MEASURES Cell count was measured using a cell viability assay on day 1, 7, and 14 for all materials. Gene expression was analyzed at day 1,7,14, and 21 using two-step RT-qPCR for the following bone markers: Alkaline Phosphatase (ALP), Vascular Endothelial Growth Factor (VEGF), Osteocalcin (OCN), and RUNX2. Substrates were compared at each time point for gene expression and cell count. METHODS Discs, 15mm in diameter, of TS, PEEK, and T3 were used to culture murine bone marrow mesenchymal stem cells (BM-MSCs). Cells were also cultured on tissue culture polystyrene (TCPS). Substrates were seeded with BM-MSCs at a density of ∼56x103 cells/cm2. RESULTS T3 exhibited higher cell count than other discs over 14 days, though significantly less than TCPS at all time points. By day 14, TCPS, T3, PEEK, and TS cultures resulted in the cell counts of (349±12, 207±10, 134±7, and 103±83)×103 cells, respectively. Cell count on T3 discs was significantly higher than TS at D1 (58±3×103 and 30±9×103 respectively), TS and PEEK at D7 (167±8 x103, 47±45×103, and 122±22×103 respectively), and PEEK at D14 (207±10×103 and 134±7×103 respectively) (p CONCLUSIONS This study suggests that 3D-printed, porous, titanium implants may provide a more osteogenic environment than smooth titanium and PEEK, since cells cultured on 3D-printed titanium exhibited higher cell counts and enhanced bone marker production compared to both smooth titanium and PEEK over 21 days. Further research is required to assess the osseointegration potential of 3D-printed porous, titanium in vivo. FDA DEVICE/DRUG STATUS HEDRON (Globus Medical) (Approved for this indication)