Effects of bone morphogenic protein-2(BMP-2) on cultured spinal ligament cells in vitro

ObjectiveTo detect the role of the BMP-2 on the ligament cells derived from patients with ossification of the posterior longitudinal ligament(OPLL).MethodsLigament specimens were obtained form non-ossified sites of OPLL patients and non-OPLL patients.Eight OPLL cell lines(OL1~OL8)and seven non-OPLL cell lines(NL1~NL7)were established.Proliferation,alkaline phosphatase(ALP)activity,collagen synthesis,osteocalcin secretion of the ligament cells cultured in vitro were detected.The expression of BMP-2 in normal and degenerative spinal ligament tissue was examined.The effects of rhBMP-2 in different concentration on the cultured cells were also detected.ResultsFour of eight OL cell lines expressed osteoblast phenotype(high ALP activity, bony tubercle,glycosaminoglycans,osteocalcin were detected).However,all seven NL cell lines had low ALP activity and no bone tubercle formation and osteocalcin were detected.BMP-2 expressed in degenerative,chondrified and ossified sites of ligament tissues, didn't express in normal spinal ligament.BMP-2 could enhance the ALP activity,osteocalcin secretion,DNA and collagen synthesis of OL cell lines.Only two of NL cell lines were with increased ALP activity and osteocalcin secretion.ConclusionCultured ligament cells from OPLL patients can express osteoblast phenotype in vitro.BMP-2 can induce osteoblast defferentiation of fibroblast.BMP-2 plays an important role in the formation of OPLL.