Decoupling the effects of collagen alignment and bioceramic incorporation on osteoblast proliferation, differentiation, and mineralization

Biomimetic scaffolds provide the essential biophysical (e.g., surface topography, stiffness) and biochemical cues (e.g., composition) to guide cell morphology, proliferation, and differentiation. Although the effects of biomaterial-directed cues on cell response have been widely reported, few studies have sought to decouple these effects to better understand the interplay between the different physicochemical factors on tissue-specific cell function. Herein, beta-tricalcium phosphate (8-TCP) was incorporated into electrochemically aligned collagen (ELAC) and random collagen threads, and the individual and interactive effects of collagen alignment (i.e., biophysical) and bioceramic incorporation (i.e., biochemical) on osteoblast cell morphology, proliferation, differentiation, and mineralization were investigated. Results showed that collagen alignment in ELAC threads was retained upon 8-TCP incorporation. Collagen alignment significantly improved (p < 0.05) the swelling capacity and stability of collagen threads, while 8-TCP incorporation showed no such effects. Tensile tests revealed that 8-TCP incorporation significantly decreased (p < 0.05) the strength and stiffness of ELAC threads. Significant increase (p < 0.05) in Saos-2 cell orientation and alkaline phosphatase (ALP) activity was observed on ELAC compared to random collagen threads indicating that aligned collagen serves as a key driving factor for osteogenesis. 8-TCP incorporation into random collagen threads had no effect on Saos-2 cell function. On the other hand, presence of 8-TCP significantly augmented (p < 0.05) Saos-2 cell metabolic activity, differentiation, and mineralization on ELAC threads. Together, these findings suggest that combining collagen alignment and 8-TCP incorporation can create robust tissue-mimicking scaffolds for bone regeneration applications.