Preparation and biocompatibility of odanacatib microspheres-gel composite sustained-release carrier

Abstract

BACKGROUND: Odanacatib effectively exerts anti-inflammatory effects and promotes alveolar bone repair in periodontitis-affected areas. However, multiple injections are required to ensure efficacy, which is cumbersome. OBJECTIVE: To prepare an odanacatib-loaded microsphere-gel composite sustained-release carrier and characterize its biocompatibility. METHODS: (1) Poly(lactic-co-glycolic acid) microspheres loaded with different masses of odanacatib (denoted as ODN-MS) were prepared by emulsion-solvent evaporation method. Based on drug loading and encapsulation efficiency, microspheres prepared with 5 mg odanacatib and 40 mg PLGA were selected for subsequent experiments. Different masses of ODN-MS were mixed with methacrylated gelatin (GelMA) solution to prepare gel composite sustained-release carriers (denoted as ODN-MS-Gel), with ODN-MS mass concentrations of 250 and 500 μg/mL. The microstructure and in vitro drug release properties of ODN-MS and 250 μg/mL ODN-MS-Gel were characterized. (2) Rabbit bone marrow mesenchymal stem cells (BMSCs) were cultured with extracts of GelMA gel, PLGA microsphere-loaded gel composite sustained-release carrier, and 250 and 500 μg/mL ODN-MS-Gel. CCK-8 assay was used to detect cell proliferation. Rabbit BMSCs were cultured with extracts of GelMA gel, PLGA microsphere-loaded gel composite sustained-release carrier, and 250 μg/mL ODN-MS-Gel. Live/dead staining was used to detect cell viability. Rabbit BMSCs were seeded on GelMA gel, PLGA microsphere-loaded gel composite sustained-release carrier, and 250 μg/mL ODN-MS-Gel. Phalloidin staining and scanning electron microscopy were used to observe cell adhesion. RESULTS AND CONCLUSION: (1) Under optical microscope, ODN-MS were spherical, uniformly distributed, and without agglomeration. Scanning electron microscopy showed that ODN-MS surface had fine porous structure; 250 μg/mL ODN-MS-Gel hydrogel had porous structure, and ODN-MS were distributed in the porous structure. Both ODN-MS and 250 μg/mL ODN-MS-Gel could achieve sustained drug release, and the 250 μg/mL ODN-MS-Gel system released drug more gently, achieving dual sustained-release effect. (2) CCK-8 assay showed that 250 and 500 μg/mL ODN-MS-Gel extracts could promote the proliferation of rabbit BMSCs. Live/dead staining showed that 250 μg/mL ODN-MS-Gel extract did not affect the viability of rabbit BMSCs. Phalloidin staining and scanning electron microscopy showed that compared with the other two materials, 250 μg/mL ODN-MS-Gel promoted the adhesion of rabbit BMSCs. These results indicate that ODN-MS-Gel can achieve sustained release of odanacatib and has good biocompatibility.

1. Introduction

Periodontitis is characterized by destruction of the gingiva, periodontal ligament, and alveolar bone, leading to severe bone loss and tooth loosening or loss [1-3]. Traditional treatments such as mechanical debridement and systemic antibiotic administration can control inflammation [4], but they are insufficient to achieve functional regeneration of alveolar bone. Moreover, existing bone graft materials lack anti-inflammatory properties [5]. Studies have shown that cathepsin K, a key enzyme in bone resorption, is significantly upregulated in periodontal tissues of periodontitis patients [6]. Therefore, inhibiting cathepsin K expression has become an effective strategy to promote inflammatory alveolar bone repair [7-8]. Odanacatib, a cathepsin K inhibitor, is currently the only drug that has completed phase III clinical trials [9]. However, long-term systemic administration increases the risk of cardiovascular and cerebrovascular diseases [10], which severely hinders its further application. Our previous research found that local application of odanacatib into periodontal pockets can promote the transformation of inflammatory granulation tissue into reparative granulation tissue and regulate M2 macrophage polarization, thereby promoting inflammatory alveolar bone defect repair [7,11]. Furthermore, experiments with knockout mice indicated that cathepsin K gene knockout or inhibition enhances the proliferation and osteogenic differentiation of jaw bone marrow mesenchymal stem cells through the glycolytic pathway [8]. These experiments all involved injection of drug solution into periodontal pockets. However, the drug solution has high fluidity and cannot remain in the periodontal pocket for a long time, requiring multiple injections to ensure efficacy, which is cumbersome and costly. Therefore, developing a local sustained-release system to achieve long-term release of odanacatib in the periodontal pocket has become an urgent problem to solve.