Osteogenic differentiation driven by osteoclasts and macrophages

Osteoclasts are bone-resorbing cells closely related to bone turnover, whereas different macrophage subtypes contribute fracture healing. As osteoclasts and macrophages share the same hematopoietic origin, difference between both cell types on osteoblast coupling, crosstalk extent consequent formation remains poorly understood. This study compares potential of primary that routinely considered as osteoclast cultures their ability support osteogenic differentiation human mesenchymal stromal (hMSCs). Human Peripheral Blood Mononuclear Cells (hPBMCs) were used obtain or using appropriate stimulatory factors. With seeding densities hPBMCs, conditioned media from harvested for comparative evaluation effects thereof hMSCs. Specific cytological staining was qualitatively evaluate cultures. Additionally, quantitative data hMSC proliferation, mineralization obtained via biochemical assays. Conditioned medium low hPBMCs densities, but not high macrophages, stimulated mineralization. Upon cellular crosstalk, pre-differentiated non-polarized equally supported early mineralization, confirmed by increased alkaline phosphatase levels within 7 days calcium content 14 in comparison with undifferentiated controls. Initial density strongly influences osteoclastogenesis paracrine effect resultant population In addition, only indirect coculture, provide similar MSCs Our results demonstrate differentiation, depending initial hPBMC density. we show contain pools polarized which may be involved effects. insight into tissue engineering approaches multicellular interactions remodeling healing vitro modulation differentiation.