Combination Therapy Using Kartogenin-Based Chondrogenesis and Complex Polymer Scaffold for Cartilage Defect Regeneration.

Articular cartilage has a highly organized structure, responsible for supporting tremendous mechanical loads. How to repair defected articular cartilage has become a great challenge as the avascular nature of cartilage limits its regenerative ability. Aiming to facilitate chondrogenic differentiation and cartilage regeneration, we recently explored a novel combination therapy using soluble poly-l-lysine/Kartogenin (L-K) nanoparticles and a poly(lactic--glycolic acid) PLGA/methacrylated hyaluronic acid (PLHA) complex scaffold. The potential use for joint cartilage reconstruction was investigated through L-K nanoparticles stimulating adipose-derived stem cells (ADSCs) on PLHA scaffolding, which ultimately differentiated into cartilage . In this study, on one hand, an effective method was established for obtaining uniform L-K nanoparticles by self-assembly. They were further proved to be biocompatible to ADSCs cytotoxicity assays and to accelerate ADSCs secreting type 2 collagen in a dose-dependent manner by immunofluorescence. On the other hand, the porous PLHA scaffold was manufactured by the combination of coprecipitation and ultraviolet (UV) cross-linking. Nanoindentation technology-verified PLHA had an appropriate stiffness close to actual cartilage tissue. Additional microscopic observation confirmed that the PLHA platform supported proliferation and chondrogenesis for ADSCs . In the presence of ADSCs, a 12-week osteochondral defect regeneration by the combination therapy showed that smooth and intact cartilage tissue successfully regenerated. Furthermore, the results of combination therapy were superior to those of phosphate-buffered saline (PBS) only, KGN, or KGN/PLHA treatment. The results of magnetic resonance imaging (MRI) and histological assessment indicated that the renascent tissue gradually regenerated while the PLHA scaffold degraded. In conclusion, we have developed a novel multidimensional combination therapy of cartilage defect repair that facilitated cartilage regeneration. This strategy has a great clinical translational potential for articular cartilage repair in the near future.