Local delivery of triamcinolone acetonide in an aclt model of osteoarthritis impairs joint regeneration, possibly by inhibition of wound healing

INTRODUCTION: Corticosteroids such as triamcinolone acetonide (TAA) are used to alleviate pain symptoms of osteoarthritic patients. Although usually pain relief is achieved, the effect wears off with time. The use of biomaterial-based local delivery systems would overcome this problem. However, little is known on the the appropriate dosing of corticosteroids in the joint. In a previous study on collagenase-induced mild OA in the rat, a limited effect on cartilage degeneration was found of TAA, either as bolus or in a polyesteramide microsphere (PEAMs) controlled release platform system. In the current study, safety, effectivity and possible side effects of TAA locally delivered by the microsphere platform at different dosages was studied in an anterior cruciate ligament transection (ACLT) and partial meniscectomy (DMM) model of rat OA, which is a more severe OA model. As damage of ligamentous structures leading to instability is a contraindication for corticosteroid therapy, despite lack of clear evidence with this respect, this was further examined. METHODS: The Utrecht University Ethical Committee for Animal Care and Use approved the study protocol (# 2014.III.10.086). OA was induced by transection of the anterior cruciate ligament and partial meniscectomy in 24 rats. Four weeks after surgery, the experimental joint was injected intra-articularly with PEAMs loaded with 0.70 mg, 1.0 mg or 1.6 mg TAA. Empty PEAMs were included as control, in addition to the contralateral healthy and untreated joints. PEAMs were administered by two injections on two consecutive days. Serum TAA levels were determined the first two weeks post-injection using HPLC analysis. Weekly pressure plate measurements were performed to monitor static weight bearing and thereby indirectly pain during a 16 week follow up. Post-mortem, histology (Mankin score) and microCT scans of all knee joints showed disease progression and possible effects on bone tissue. From healthy animals, patella, collateral and cruciate ligament explants were cultured in expansion medium consisting of DMEM (high glucose, GlutaMAX(TM), pyruvate) supplemented with 10% fetal bovine serum, 1% ascorbic acid 2-phosphate and 1% penicillin/streptomycin for 10 days with or without TAA (100 muM) added to the medium. After culture, the presence of fibroblasts migrating out of the tissue and adhering to the bottom of the culture dish was assessed. Differences in calcium deposition by microCT were evaluated by one-way analysis of variance (ANOVA). In vitro data on ligament cell outgrowth was categorized into "migration/adherence" and "no migration/adherence" and a Fisher's Exact test was performed to evaluate significant differences in the migration/adherence of ligament fibroblasts in the presence or absence of TAA. P