Effects Of Parathyroid Hormone (1-34) On Osteoarthritis Of Guinea Pigs In Vivo And In Vitro

Objective This study aimed to assess whether parathyroid hormone PTH (1-34) couldimprove the micro-structure of subchondral bone, and protect against cartilagedegradation in a naturally occurring OA of guinea pigs, and explore if PTH (1-34) has aprotective effect on IL-1β-induced chondrocyte of guinea pigs in vitro.Method1Thirty-six1-month-old guinea pigs were divided into two groups:24wereuntreated and sacrificed at1,3,6and9months of age; the other12received PTH (1-34)(15ug/kg/day,5days weekly) from3months of age, and were sacrificed at6and9months. Masson staining and Mankin scores were carried out to assess cartilagedegradation. Immunohistochemistry analyses of type-II collagen, matrixmetalloproteinases-13(MMP-13) in the cartilage.2In this study, the chondrocytesobtained from articular surface of1-month-old healthy guinea pigs and we used trypsindigestion method for the cultivation of chondrocytes. The chondrocytes were identifiedby Toluidin Blue staining. MTT assay was detected the effect of PTH on vitality ofchondrocytes in vitro，in order to ensure the concentration of this study.10ng/mlrecombinant human IL-1β expossures interference of normal guinea pig articularchondrocytes and induced OA chondrocyte-like changes.In research, we used the thirdpassage and had three groups, scilicet control group, IL-1β group and PTH10-7Mgroup.We used Western blot to detect collagen type II and matrix metalloproteinase-13factors.Results1Histological and Mankin score analyses revealed OA occurred at3months ofage and was more severe with increasing age. SbBMD increases with the development ofarthritis which declines significantly after PTH (1-34) treatment. When compared withthe age-matched control groups，immunohistochemical staining demonstrated that PTH(1-34) treatment increased type-II collagen expression and decreased MMP-13expression in the cartilage.2The isolated and cultured chondrocytes of guinea pigs invitro proliferated fastly, chondrocytes began adherence after about2hours, and theygradually greated after10hours, and the form was round or polygonal. After about2days, the chondrocytes aggregated and can be subcultured. Compared with the culturedrabbit, rat, mouse and human knee cartilage cell, cycle was obviously shortened to save experimental time.3The Phaenotype of chondrocytes was metachromasia by ToluidinBlue staining.4The result of MTT assay: The vitality of chondrocytes in PTH (1-34)10-7M group was significantly increased than that in control group.5The result of Westernblot：Compared with control group, when expossuring IL-1β, the level of Col IIsignificantly reduced and the level of MMP-13significantly increased. Compared withIL-1β group, after PTH (1-34), the level of Col II increased and the level of MMP-13wasdecreased.Conclusion1PTH (1-34) can prevent cartilage damage progression and retard thedeterioration of subchondral trabecular bone in a naturally occurring OA model.2Theisolated and cultured chondrocytes of guinea pigs in vitro proliferated fastly and theperiod of experiment is short. Chondrocytes in vitro experimental study was conductedby a better choice.3PTH (1-34)10-7M was the more suitable concentration that acted onIL-1β-induced chondrocytes of guinea pigs in vitro and PTH (1-34) has a protectiveeffect.