Department of Immunology, Tufts University School of Medicine, 136 Harrison Ave, Boston, MA, United States of America.
Remedium Bio, Inc. 1116 Great Plain Ave, Suite 203, Needham, MA, United States of America.
Curr Gene Ther. 2024;24(4):331-345. doi: 10.2174/0115665232275532231213063634.
Osteoarthritis (OA) is a highly debilitating, degenerative pathology of cartilaginous joints affecting over 500 million people worldwide. The global economic burden of OA is estimated at $260-519 billion and growing, driven by aging global population and increasing rates of obesity. To date, only the multi-injection chondroanabolic treatment regimen of Fibroblast Growth Factor 18 (FGF18) has demonstrated clinically meaningful disease-modifying efficacy in placebo-controlled human trials. Our work focuses on the development of a novel single injection disease-modifying gene therapy, based on FGF18's chondroanabolic activity.
OA was induced in Sprague-Dawley rats using destabilization of the medial meniscus (DMM) (3 weeks), followed by intra-articular treatment with 3 dose levels of AAV2-FGF18, rh- FGF18 protein, and PBS. Durability, redosability, and biodistribution were measured by quantifying nLuc reporter bioluminescence. Transcriptomic analysis was performed by RNA-seq on cultured human chondrocytes and rat knee joints. Morphological analysis was performed on knee joints stained with Safranin O/Fast Green and anti-PRG antibody.
Dose-dependent reductions in cartilage defect size were observed in the AAV2-FGF18- treated joints relative to the vehicle control. Total defect width was reduced by up to 76% and cartilage thickness in the thinnest zone was increased by up to 106%. Morphologically, the vehicle- treated joints exhibited pronounced degeneration, ranging from severe cartilage erosion and bone void formation, to subchondral bone remodeling and near-complete subchondral bone collapse. In contrast, AAV2-FGF18-treated joints appeared more anatomically normal, with only regional glycosaminoglycan loss and marginal cartilage erosion. While effective at reducing cartilage lesions, treatment with rhFGF18 injections resulted in significant joint swelling (19% increase in diameter), as well as a decrease in PRG4 staining uniformity and intensity. In contrast to early-timepoint RNA-seq analysis, which showed a high degree of concordance between protein- and gene therapy-treated chondrocytes, transcriptomic analysis, revealed few gene expression changes following protein treatment. On the other hand, the gene therapy treatment exhibited a high degree of durability and localization over the study period, upregulating several chondroanabolic genes while downregulating OA- and fibrocartilage-associated markers.
FGF18 gene therapy treatment of OA joints can provide benefits to both cartilage and subchondral bone, with a high degree of localization and durability.
骨关节炎（OA）是一种严重的软骨关节退行性疾病，全球有超过 5 亿人受其影响。OA 的全球经济负担估计为 2600 亿至 5190 亿美元，并呈增长趋势，这是由于全球人口老龄化和肥胖率上升所致。迄今为止，只有成纤维细胞生长因子 18（FGF18）的多关节注射软骨形成治疗方案在安慰剂对照的人体试验中显示出具有临床意义的疾病改善疗效。我们的工作重点是开发一种新的单关节注射疾病修饰基因治疗方法，该方法基于 FGF18 的软骨形成活性。
使用内侧半月板不稳定（DMM）（3 周）在 Sprague-Dawley 大鼠中诱导 OA，然后用 3 个剂量水平的 AAV2-FGF18、rh-FGF18 蛋白和 PBS 进行关节内治疗。通过定量 nLuc 报告基因生物发光来测量耐久性、可重复使用性和生物分布。通过对培养的人软骨细胞和大鼠膝关节进行 RNA-seq 分析进行转录组分析。用番红 O/快绿和抗 PRG 抗体对膝关节进行形态学分析。
与载体对照组相比，AAV2-FGF18 治疗关节的软骨缺陷大小呈剂量依赖性减小。总缺陷宽度减少了 76%，最薄区域的软骨厚度增加了 106%。形态学上，载体治疗的关节表现出明显的退化，范围从严重的软骨侵蚀和骨空洞形成到软骨下骨重塑和近完全软骨下骨塌陷。相比之下，AAV2-FGF18 治疗的关节看起来更解剖正常，只有局部糖胺聚糖丢失和边缘软骨侵蚀。尽管 rhFGF18 注射治疗有效减少了软骨损伤，但治疗会导致关节肿胀（直径增加 19%），以及 PRG4 染色均匀性和强度降低。与早期时间点的 RNA-seq 分析相比，蛋白质和基因治疗的软骨细胞具有高度的一致性，而转录组分析显示，蛋白质治疗后基因表达变化很少。另一方面，基因治疗在研究期间表现出高度的耐久性和定位性，上调了几个软骨形成基因，同时下调了 OA 和纤维软骨相关标志物。
FGF18 基因治疗 OA 关节可以同时改善软骨和软骨下骨，具有高度的定位性和耐久性。
