[Modulation of osteogenic differentiation in mouse osteoprogenitor cells by curved microgrooves with varied roughness...

Objective: To construct curved microgrooves with gradient surface roughness on polycaprolactone (PCL) members by regulating alkali etching time and to investigate the synergistic effect of surface roughness and curved microgrooves on the in vitro osteogenic differentiation of mouse pre-osteoblasts (MC3T3-E1), aiming to determine the optimal PCL surface modification strategy. Methods: Soft lithography and melt-casting techniques were used to fabricate PCL membranes with regularly arranged curved microgrooves (CMP). Alkali etching was performed for 24, 48, and 72 h. Groups: smooth PCL (control), CMP (curved microgrooves only), CMP-24 h, CMP-48 h, CMP-72 h (CMP etched for 24, 48, 72 h, respectively). Surface physicochemical properties were characterized: surface morphology was observed by scanning electron microscopy (SEM), surface roughness was measured by atomic force microscopy (AFM), and surface hydrophilicity was evaluated by contact angle measurement. MC3T3-E1 cells were cultured in vitro. Cell adhesion, proliferation, and osteogenic differentiation were assessed using cell counting (CCK-8), immunofluorescence staining, alkaline phosphatase (ALP) and Alizarin red staining with quantification. The mRNA expression levels of osteogenesis-related genes [ALP, collagen type Ⅰ (COL-1), Runt-related transcription factor 2 (RUNX-2), osteocalcin (OCN), osteopontin (OPN)] were detected by real-time fluorescence quantitative PCR (RT-qPCR). Results: Curved microgrooves were successfully fabricated on PCL membranes. Alkali treatment improved surface hydrophilicity and increased roughness. The CMP-72 h group exhibited the best hydrophilicity (contact angle: 33.2°±5.5°), with significant differences compared to all other groups (all P<0.05). The CMP-72 h group showed the highest roughness [(59.966±4.729) nm], which was significantly different from all other groups (all P<0.05). CCK-8 results on day 5 showed that both curved microgrooves and roughness promoted cell proliferation: CMP-24 h (0.292±0.003) and CMP-72 h (0.383±0.004) were significantly higher than those in the smooth group (0.270±0.005) (all P<0.05). Immunofluorescence staining revealed that curved microgrooves induced significant contact guidance of cells; this effect weakened with increasing etching time. ALP and Alizarin red staining indicated the deepest osteogenic staining in the CMP-48 h group. Both ALP activity (0.013 021±0.000 032) and Alizarin red quantification (0.290±0.003) were highest in the CMP-48 h group, significantly different from all other groups (all P<0.05). RUNX-2 expression in CMP-24 h and CMP-48 h groups (1.845±0.087 and 1.837±0.027, respectively) was significantly higher than in other groups (all P<0.05), with no significant difference between these two groups (P>0.05). CMP-48 h group exhibited the highest mRNA expression of all osteogenic genes tested, specifically ALP (2.194±0.028), COL-1 (1.983±0.024), OCN (7.644±0.156), and OPN (2.648±0.031), all significantly greater than other groups (all P<0.05). Conclusions: Both curved microgrooves and surface roughness modification enhance the in vitro osteogenic differentiation of cells on PCL membranes. Among the tested strategies, alkali etching of curved microgrooves for 48 hours (CMP-48h) provided the optimal enhancement of osteogenic capability for MC3T3-E1 cells and represented a promising surface modification strategy for future PCL membranes.