Expression And Significance Of Transcription Factor Runx2 And Bone Morphogenetic Protein-2 (BMP-2) In Osteoblasts From Patients With Adolescent Idiopathic Scoliosis

Expression and significance of transcription factor Runx2 and bone morphogenetic protein-2 (BMP-2) in osteoblasts from patients with adolescent idiopathic scoliosisPartⅠIsolation, cultivation, amplification and phenotype identification of osteoblasts from adolescent subjects in vitro Objective To establish the methods of the isolation,cultivation and amplification of osteoblast (OB) from adolescent subjects in vitro.Methods This study covered 26 female adolescent idiopathic scoliosis (AIS) subjects who underwent spinal surgery from March 2008 to April 2009. According to the status of bone mass, AIS patients were divided into two groups: Group A and Group B. Patients in Group A (15 cases) maintained normal BMD. While patients in Group B (11 cases) suffered from osteopenia. The cancellous bone was harvested from the posterior superior iliac spine of the subjects. The chipped explants were cultured to obtain the osteoblasts. The incremet time of each generation were recorded. The second generation (P2) cells were scraped to count. Formation of calcium nodules,staining of alkaline phosphatase and expression of osteocalcin mRNA detected by RT-PCR were used to confirm the osteoblast phenotype.Results Cell outgrowths appeared after 5-6 days,and then turned to be fusiform in shape and confluent cultures after 4 weeks. 0.5×107 cells could be obtained in each P2 generation culture flask. The positive results of staining of alkaline phosphatase, formation of calcium nodules and expression of osteocalcin confirmed that the P2 cells were typical osteoblasts. There was no statistical difference between the two study groups about increment time of osteoblasts.Conclusion 1. Explant culture system offers copious primary osteoblasts with good cellular characters, it is an ideal culture system for human osteoblasts. 2. Osteoblast from adolescent idiopathic scoliosis in the two study groups has the same capacity of growth and proliferation in vitro. PartⅡThe Association between Runx2, BMP-2 in osteoblasts and the Decreased Bone Mass in Adolescent Idiopathic Scoliosis PatientsObjective To investigate the association between bone morphogenetic proteins-2 (BMP-2), transcription factor Runx2 in osteoblasts and the decreased bone mass of adolescent idiopathic scoliosis patients.Methods This study included 26 female AIS subjects (aged from 12 to 18) who underwent spinal surgery from March 2008 to April 2009. According to the status of bone mass, AIS patients were divided into two groups: Group A and Group B. Patients in Group A (15 cases) had normal BMD. While patients in Group B (11 cases) suffered from osteopenia. The average age was 14.6 years in Group A and 14.8 years in Group B. BMD of the lumbar spine and proximal femur was measured using dual energy X-ray absorptiometry in both groups. The cancellous bone was harvested from the posterior superior iliac spine of the subjects. The chipped explants were cultured to obtain the osteoblasts. Expression of transcription factor Runx2 and bone morphogenetic proteins-2 (BMP-2) of P2 generation osteoblasts from two groups were detected by using RT-PCR and Western blotting.Results BMD of the lumbar spine (L2~L4) and proximal femur in Group B was obviously lower than that in Group A. RT-PCR and Western blotting results showed that:1) Expression of BMP-2 in osteoblasts was comparable between two study group (P>0.05). 2) Expression of Runx2 in Group B were obviously decreased as compared with that in Group A (P<0.05).Conclusion The expression of BMP-2 in OB may not associated with the reduced BMD in AIS, while the abnormal expression of Runx2 may play an important role in the pathogenesis of reduced BMD in AIS.