Effects of trabecular calcium phosphate scaffolds on stress signaling in osteoblast precursor cells

The objective of this research was to investigate stress-signaling patterns in response to two-dimensional (2-D) and three-dimensional (3-D) calcium phosphate (CP) materials using human embryonic palatal mesenchyme cells (HEPM, CRL-1486, ATCC, Manassas, VA), an osteoblast precursor cell line. Control discs and scaffolds were fabricated from hydroxyapatite and beta tri-CP ceramics. Phospho-specific antibody cell-based ELISA technique was utilized on members of the mitogen-activated protein kinase cascade including; the extracellular signal-regulated kinases (ERK1/2), p38, c-Jun N-terminal kinase (JNK), and the anti-apoptosis mediator protein kinase B (AKT). Quantification of these signals was evaluated during the early attachment phase of osteoblast precursor cells. In this study, it was observed that 3-D CP scaffolds significantly activated the stress mediators p38 and JNK but not ERK1/2. This signal trend was matched with an up-regulation in AKT, suggesting the ability of cells to manage high stress signals in response to 3-D CP architecture and that 3-D CP scaffolds are necessary for studies simulating a natural trabecular bone organization. The absence of these signals in 2-D CP surfaces indicated the importance of local architecture conditions on cell stress response. It was concluded from this study that osteoblast precursor cells cultured in 3-D CP scaffolds experience greater stress-signaling patterns when compared to 2-D CP surfaces.