Department of Biomedical Engineering, University of California, Davis, CA 95616, USA; Laboratory of Natural Products, Chulabhorn Research Institute, Bangkok 10210, Thailand.
Department of Orthopaedic Surgery, School of Medicine, University of California, Davis, CA 95618, USA.
Acta Biomater. 2022 Sep 1;149:347-358. doi: 10.1016/j.actbio.2022.06.042. Epub 2022 Jun 30.
Rapid joint clearance of small molecule drugs is the major limitation of current clinical approaches to osteoarthritis and its subtypes, including post-traumatic osteoarthritis (PTOA). Particulate systems such as nano/microtechnology could provide a potential avenue for improved joint retention of small molecule drugs. One drug of interest for PTOA treatment is flavopiridol, which inhibits cyclin-dependent kinase 9 (CDK9). Herein, polylactide-co-glycolide microparticles encapsulating flavopiridol were formulated, characterized, and evaluated as a strategy to mitigate PTOA-associated inflammation through the inhibition of CDK9. Characterization of the microparticles, including the drug loading, hydrodynamic diameter, stability, and release profile was performed. The mean hydrodynamic diameter of flavopiridol particles was ∼15 µm, indicating good syringeability and low potential for phagocytosis. The microparticles showed no cytotoxicity in-vitro, and drug activity was maintained after encapsulation, even after prolonged exposure to high temperatures (60 °C). Flavopiridol-loaded microparticles or blank (unloaded) microparticles were administered by intraarticular injection in a rat knee injury model of PTOA. We observed significant joint retention of flavopiridol microparticles compared to the soluble flavopiridol, confirming the sustained release behavior of the particles. Matrix metalloprotease (MMP) activity, an indicator of joint inflammation, was significantly reduced by flavopiridol microparticles 3 days post-injury. Histopathological analysis showed that flavopiridol microparticles reduced PTOA severity 28 days post-injury. Taken altogether, this work demonstrates a promising biomaterial platform for sustained small molecule drug delivery to the joint space as a therapeutic measure for post-traumatic osteoarthritis. STATEMENT OF SIGNIFICANCE: Post-traumatic osteoarthritis (PTOA) begins with the deterioration of subchondral bone and cartilage after acute injuries. In spite of the prevalence of PTOA and its associated financial and psychological burdens, therapeutic measures remain elusive. A number of small molecule drugs are now under investigation to replace FDA-approved palliative measures, including cyclin-dependent kinase 9 (CDK9) inhibitors which work by targeting early inflammatory programming after injury. However, the short half-life of these drugs is a major hurdle to their success. Here, we show that biomaterial encapsulation of Flavopiridol (CDK9 inhibitor) in poly (lactic-co-glycolic acid) microparticles is a promising route for direct delivery and improved drug retention time in the knee joint. Moreover, administration of the flavopiridol microparticles reduced the severity of PTOA.
小分子药物的快速关节清除是当前治疗骨关节炎及其亚型（包括创伤后骨关节炎（PTOA））的临床方法的主要限制。微粒系统（如纳米/微技术）可为改善小分子药物在关节中的保留提供潜在途径。用于 PTOA 治疗的一种药物是 flavopiridol，它能抑制细胞周期蛋白依赖性激酶 9（CDK9）。本文中，我们制备了包封 flavopiridol 的聚乳酸-共-羟基乙酸微球，并对其进行了表征，将其作为通过抑制 CDK9 减轻 PTOA 相关炎症的策略进行了评估。对微球进行了表征，包括药物包封率、水动力学直径、稳定性和释放特性。flavopiridol 颗粒的平均水动力学直径约为 15 µm，表明其具有良好的可推注性和低吞噬作用潜力。体外微球无细胞毒性，即使在暴露于高温（60°C）后，药物活性在包封后仍能保持。flavopiridol 负载微球或空白（未负载）微球通过关节内注射施用于 PTOA 的大鼠膝关节损伤模型。与可溶性 flavopiridol 相比，我们观察到关节中 flavopiridol 微球的保留明显增加，证实了颗粒的持续释放行为。基质金属蛋白酶（MMP）活性是关节炎症的指标，在损伤后 3 天，flavopiridol 微球显著降低了 MMP 活性。组织病理学分析表明，flavopiridol 微球在损伤后 28 天降低了 PTOA 的严重程度。总的来说，这项工作展示了一种有前途的生物材料平台，可用于将小分子药物持续递送到关节间隙，作为治疗创伤后骨关节炎的一种手段。
创伤后骨关节炎（PTOA）始于急性损伤后软骨下骨和软骨的恶化。尽管 PTOA 很普遍，且其相关的经济和心理负担很大，但治疗方法仍难以捉摸。目前有许多小分子药物正在研究中，以替代 FDA 批准的姑息性治疗方法，包括细胞周期蛋白依赖性激酶 9（CDK9）抑制剂，其通过靶向损伤后的早期炎症编程起作用。然而，这些药物的半衰期短是其成功的主要障碍。在这里，我们表明，flavopiridol（CDK9 抑制剂）的生物材料包封在聚（乳酸-共-羟基乙酸）微球中是一种很有前途的直接递送途径，并可以改善药物在膝关节中的保留时间。此外，flavopiridol 微球的给药降低了 PTOA 的严重程度。
