Effect of controlled released PTH (1-34) encapsulated PLGA microspheres on treatment of early osteoarthritis in rat

INTRODUCTION: Parathyroid hormone (PTH) is an 84 amino acid polypeptide that acts as the most important regulator of calcium homeostasis in the human body through its direct action on bone and kidney. Previously we reported that PTH(1-34) inhibits terminal differentiation of articular chondrocytes and in turn suppresses the progression of osteoarthritis (OA). However, the treatment needs the injection of PTH every 3 days over the treatment period. We hypothesized that encapsulation of PTH(1-34) in PLGA microspheres with controlled release property may prolong the injection durations and can be used to treat OA with less injection frequency. Here in we studied the effect of released PTH(1-34) from PLGA(65:35) encapsulated PTH(1-34) (PLGA/PTH) microspheres on the papain-induced OA in the rat knee joints. In vitro study, we studied the microspheres morphology, PTH(1-34) encapsulation efficiency, release profile, bioactivity. In vivo study, we evaluated the changes of localized glycosaminoglycan (GAG), Type II collagen and Type X collagen in the articular cartilage of rat knee.