Delivery of FBXO6 with highly branched poly(β-amino ester)s to modulate the inflammatory environment for the treatment of osteoarthritis

Osteoarthritis (OA) is a chronic joint disease characterized by the progressive degradation of articular cartilage. Delivering functional genes to chondrocytes to modulate the inflammatory environment offers a promising approach to treating OA. However, the dense extracellular matrix (ECM) in the OA microenvironment and the rapid clearance of naked nucleic acids from synovial fluid present significant challenges. Here we report the development of highly branched poly(beta-amino ester)s (HPAEs) for effective delivery of F-box protein 6 (FBXO6) gene to treat OA. Four HPAEs were synthesized using an "A2 + B4 + C2" Michael addition strategy. By optimizing the chemical compositions and topological structures, the optimal HMDA-2 was identified to exhibit superior transfection efficiency, outperforming the commercial reagents Lipofectamine 3000 and branched polyethyleneimine (PEI). HMDA-2 was further employed to deliver FBXO6 plasmid to effectively regulate H2O2 expression, improve oxidative stress injury, and reduce the expression of MMP-13 and COX-2 in chondrocytes, leading to significant reductions in synovial inflammatory cell infiltration, cartilage loss, and bone erosion. After intra-articular injection in an anterior cruciate ligament transection (ACLT) rat model, HMDA-2/FBXO6 polyplexes substantially reduced synovitis and cartilage damage, improved cartilage surface integrity, and restored proteoglycan levels. The delivery of FBXO6 with HMDA-2 to chondrocytes offers a potential treatment for OA.