Use of a rotary bioreactor for growth and differentiation of mesenchymal stem cells

Bone graft generation in vitro is limited by slow nutrient-waste exchange through thick scaffolds and insufficient mechanical stimuli required for induction and differentiation of osteoprogenitor cells, often requiring the use of suitable bioreactors to circumvent these limitations. In this study, we test the suitability of a modified rotary miniPERM¿ bioreactor system in inducing proliferation and osteodifferentiation of human foetal mesenchymal stem cell (hfMSC) on poly-¿-caprolactone (PCL)tricalcium phosphate (TCP) scaffolds. Briefly, 0.5×10⁶ hfMSC were seeded onto PCLTCP scaffolds and cultured for 7 days at rotation speeds of 15 and 20 rpm in a modified miniPERM¿ bioreactor with static culture as control. Proliferation of hfMSC in 20 rpm dynamic culture was better than 15 rpm, as evidenced by results from PicoGreen® double-stranded DNA quantitation, light and confocal laser microscopy. Consequently, 20 rpm rotational speed was used to induce and study osteogenesis of hfMSC on identical scaffolds. Seeded scaffolds were cultured for 28 days in 3 conditions, viz. dynamic osteoinduced, dynamic uninduced and static osteoinduced cultures. We found that the dynamic induced scaffolds in the modified miniPERM¿ had undergone osteoinduction with 1.5 times more ALP activity and 3.5 times more calcium deposition, as compared to its static induced controls. We also noted that a low baseline level of bone induction was seen in the uninduced dynamic culture. This suggests that both osteogenic medium and appropriate mechanostimulation are critical to effect full osteodifferentiation of hfMSCs. The use of a modified miniPERM¿ bioreactor system can improve cellular viability over static cultures, with increased proliferation and osteogenic differentiation in vitro.