Biological features of osteoblasts isolated from patients with type Ⅰ neurofibromatosis / 中华骨科杂志

ABSTRACT

Objective To detect the neurofibromin expression and observe the biological features of the osteoblasts of patients with type 1 neurofibromatosis and scoliosis. Methods 10 cases of congenital scoliosis and 8 cases of NF1 scoliosis were chosen. The two groups were with the similar age(with the average of 11.7 years and 12.5 years) and Cobb angle(with the average of 85? and 94?). Cancellous bone was harvested from the ilia and the bone explants culture system was used. Proliferation of the osteoblasts, and also the specific differentiation index including alkaline phosphatase, type Ⅰ collagen and osteocalcin was assayed in sewnd generation osteoblasts. Neurofibromin expression in the two kinds of osteoblasts was detected with immunoprecipitation followed by Western blot. Results Compared to the osteoblasts of patients with congenital scoliosis, lower level of neurofibromin was expressed in osteoblasts of patients with NF1 scoliosis, (the OD value was 1.05?0.06 and 2.59?1.40 respectively, P=0.002). The level of alkaline phosphatase, type Ⅰ collagen and osteocalcin were significant lower in osteoblasts of patients with NF1 scoliosis than those of CS patients (44.69 IU/mg vs 51.38 IU/mg, P=0.019; 226.34 ng/mg vs 249.93 ng/mg, P=0.014; 7.41 ng/mg vs 8.87 ng/mg, P=0.049). But the proliferation rate of the NF1 osteoblasts was significant higher than that of the CS osteoblasts (3.34 and 2.70 respectively, P=0.049). Conclusion With the decrease of neurofibromin expression, the NF1 osteoblasts show some defects in their function, these function defects may contribute to varieties of skeletal abnormalities as dystrophic change and decreased bone density.