Involvement of bone morphogenic protein-2 (BMP-2) in the pathological ossification process of the spinal ligament

Objective. To investigate the function of bone morphogenic protein-2 (BMP-2 ) in the ossification of the spinal ligament (OSL). Methods. Total RNA was prepared from the cultured spinal ligament cells fro m patients with OSL and analysed by reverse transcription-polymerase chain reaction using specific primers for BMP-2. BMP-2 mRNA expression in ligamen t tissues was examined by in situ hybridization. Spinal ligament cells from patients without OSL were treated with BMP-2 and examined for alkaline pho sphatase activity. Results. Expression of the BMP-2 gene was detected in cultured spinal ligam ent cells. In ligament tissues, BMP-2 mRNA was present in the chondrocyte-l ike cells in the fibrocartilage zone. Exogenous BMP-2 increased alkaline ph osphatase activity in spinal ligament cells from patients without OSL. Conclusion. The BMP-2 gene is expressed in the spinal ligaments of OSL pati ents, and exogenous BMP-2 stimulates osteogenic differentiation of spinal l igament cells. The expression of BMP-2 in the spinal ligaments could be a c lue in elucidating how heterotrophic osteogenesis develops in ligament tiss ue.