Co-stimulation with equibiaxial strain and pre-osteoblast co-culture differentiates monocytes in a bone model.

Bone remodeling and immune function are dynamically regulated through cell-cell and cell-matrix interactions by stem and mature cell populations. We investigated the hypothesis that monocytes and pre-osteoblasts respond to cyclic tensile stress and paracrine interactions by differentiating into macrophage-like and osteoblast-like cells. 20% cyclic equibiaxial strain was applied to monocytic U937 and pre-osteoblastic ST2 cells for 72 h. Increased levels of CD11B, CD14, IL-6, and IL-8 in U937 indicated monocytic differentiation. Increased ALP expression and calcium deposition in ST2 indicated differentiation towards osteoblastic lineage. Overall, application of cyclic strain and pre-osteoblastic co-culture induced differentiation in this cyclically strained bone model.