Stimuli-Responsive Transfersome-Based Bio-Mimetic Gels for Intra-Articular Drug Delivery in Osteoarthritis

Abstract

Osteoarthritis (OA) is one of the most prevalent debilitating joint diseases affecting over 7.6% of the global population. This disease is primarily characterized by cartilage degeneration, leading to pain, inflammation, and stiffness in affected joints. Current commercial treatment options for OA are mainly symptomatic and palliative. These include the pain and inflammation medicines acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, and opioids. However, these are associated with limitations such as gastric ulceration and acute kidney injury with classical NSAIDs, increased risk of cardiovascular disease with cyclooxygenase-2 (COX-2) selective inhibitors and the need for repeated intra-articular (IA) injections with glucocorticoids which, apart from increasing the risk for exposure to infections, are not cost-effective and often results in low patient compliance. However, to mitigate some of these drawbacks, stimuli-responsive drug delivery systems, such as nanocomposites, offer a promising approach to effective and sustainable treatment of OA. In this study, we investigated the use of dexamethasone (DEX)-loaded tNPs nanoparticles (tNPs) incorporated in a Pluronic F-127/hyaluronic acid (PF-127/HA) hydrogel to treat OA. DEX, a potent anti-inflammatory and immunosuppressive agent, has been used for treatment of various inflammatory disorders, including OA. DEX-loaded transfersomes (tNPs) were synthesized using thin-film hydration and incorporated into a thermo-responsive hydrogel composed of Pluronic F-127 (PF-127) and hyaluronic acid (HA). The formulation was evaluated for morphology, particle size, zeta potential, encapsulation efficiency, physiochemical characteristics, rheological properties, syringeability and drug release. In vitro release studies were conducted using a knee joint simulator to mimic physiological conditions. Biocompatibility was assessed using RAW 264.7 macrophages via MTT and IL-4 quantification assays to determine cytotoxicity and anti- inflammatory potential. From the microscopic analysis (Scanning electron and transmission electron microscopy), the DEX-loaded tNPs had a hydrodynamic size of 76.43 ± 0.48 nm depicting a smooth and spherical morphology. Moreover, these tNPs had a remarkable EE of 98 ± 0.31%. The DEX- loaded tNPs also demonstrated high stability with insignificant changes in size, size distribution, and zeta potential over a period of 3 months. The amount of force required to extrude the hydrogel from a standard 22-gauge needle was 24 N, suggesting the required ease of injection. The drug release kinetic profile of these tNPs showed approximately 90% DEX release after 72 hrs, which, however, improved to approximately 2 months (7 weeks) 19 upon incorporation into the hydrogel matrix. In a knee joint simulator, the in vitro DEX release was confirmed to be 2 months from this nanosystem. The rheological analysis showed promising mechanical properties such as stress sweep, thixotropy, yield stress, and frequency sweep, signifying the suitability of the hydrogel for the IA administration in OA joints. Furthermore, cell culture studies showed that the nanocomposite was biocompatible with RAW 264.7 macrophage cells, maintaining cell viability above 70%. Interleukin-4 (IL-4) quantification revealed that Blank-tNPs hydrogel induced the highest anti-inflammatory response, while DEX encapsulation slightly reduced IL- 4 secretion Taken together, the results from this study suggest that the developed DEX-tNPs-P127/HA hydrogel exhibited ideal physicochemical, rheological, and drug release properties for sustained IA delivery in OA. The formulation holds promise as a novel IA therapy, reducing injection frequency while maintaining therapeutic efficacy. However, further in vivo studies are warranted.