Development of Injectable Aldehyde Hyaluronic Acid Hydrogels Loaded with CRISPRa Reprogrammed Elite Macrophages for the Treatment of Osteoarthritis.

Osteoarthritis (OA) is a common joint disorder that causes significant disability. Previous studies suggested that the predominance of M1 macrophages (MΦs) exacerbates inflammation and cartilage degradation in OA, suggesting that shifting the polarization toward M2 MΦs could be a promising therapeutic strategy. We recently developed CRISPRa-engineered macrophages, termed Elite MΦs, that express IL-10 and maintain a stable M2 phenotype. However, achieving effective and sustained delivery of these cells to the OA joint remains a challenge. In this study, we synthesized two injectable aldehyde hyaluronic acid-based hydrogels, CHO/CDH and ACHO/CDH hydrogels, to serve as Elite MΦ delivery platforms. Comprehensive analyses identified the ACHO/CDH hydrogel as superior due to its enhanced suitability for encapsulating and delivering Elite MΦs. When loaded with Elite MΦs, the ACHO/CDH hydrogel was able to not only localize Elite MΦs but also enhance their anti-inflammatory and reparative effects. Furthermore, intra-articular injection of the Elite MΦ-loaded ACHO/CDH hydrogel in an OA mouse model resulted in notable improvements in the joint's cellular environment, alleviating cartilage degradation and synovial inflammation. These results highlight the ability of the ACHO/CDH hydrogel to rebalance the inflammatory imbalance and promote cartilage repair. This approach not only targets the underlying inflammatory processes more directly than traditional therapies but also harnesses the regenerative potential of macrophages, offering a transformative strategy for OA management.