Flow perfusion culture of human mesenchymal stem cells on silicate-substituted tricalcium phosphate scaffolds

Autologous bone grafts are currently the gold standard for treatment of large bone defects, but their availability is limited due to donor site morbidity. Different substitutes have been suggested to replace these grafts, and this study presents a bone tissue engineered alternative using silicate-substituted tricalcium phosphate (Si-TCP) scaffolds seeded with human bone marrow-derived mesenchymal stem cells (hMSC). The cells were seeded onto the scaffolds and cultured either statically or in a perfusion bioreactor for up to 21 days and assessed for osteogenic differentiation by alkaline phosphatase activity assays and by quantitative real-time RT-PCR on bone markers. During culture, cells from the flow cultured constructs demonstrated improved proliferation and osteogenic differentiation verified by a more pronounced expression of several bone markers, e.g. alkaline phosphatase, osteopontin, Runx2, bone sialoprotein II, and bone morphogenetic protein 2. Cells and matrix were distributed homogenously throughout the entire scaffold in flow culture, whereas only a peripheral layer was obtained after static culture. A viable and homogenous ex vivo bone construct with superior osteogenic properties was produced in dynamic culture and may provide a replacement for autologous grafts.