Effect of different incubation durations of β-TCP/BMSCs tissue engineering bone on the posterolateral spinal fusion in rabbits

Abstract

Objective To investigate appropriate incubation time of bone marrow stem cells (BMSCs) combined with β-tricalcium phosphate (β-TCP) for the posterolateral spinal fusion in rabbits.Methods The rabbit BMSCs were isolated and cultured to induce osteoblasts in vitro.The same amounts of osteoblasts were seeded onto β-TCP for static incubation of 1,3 and 7 days respectively before implantation into New Zealand rabbits for the posterolateral spinal fusion.The cell viability was observed by MTI,scanning electron microscopy and fluorescent staining.The rabbits were sacrificed 12 weeks postoperation for radiological,histological and histomorphometry observations of new bone formation and lumbar fusion.Results The cell viability was 0.19 ± 0.02 A/g for incubation of one day,0.48 ± 0.06 A/g for incubation of 3 days and 0.61 ±0.05 A/g for 7 days,with a significant between-group difference (F =175.570,P =0.000).Scanning electron microscopy and fluorescent staining showed fine growth of the cells.At 12 weeks the X-ray score,spinal fusion rate,bone mineral content (BMC),bone volume fraction (BV/TV) value,percentage of new bone formation for incubation of one day were all significantly lower than those for incubation of 3 and 7 days( P ＜ 0.05),but there was no significant difference between incubation of 3 days and incubation of 7 days ( P ＞ 0.05 ).Conclusions The posterolateral spinal fusion is significantly affected by the incubation time of β-TCP/BMSCs,but the incubation time is not proportional to the fusion effect,suggesting that the incubation time may have a critical value. Key words: Calcium phosphates; Bone marrow cells; Spinal fusion; Tissue engineering