Three-dimensional stem cell microcarrier/platelet-rich plasma functionalized injectable hydrogel scaffold for cartilage repair

Articular cartilage repair is a significant clinical challenge due to its avascular nature and limited regenerative capacity, with current treatments often yielding suboptimal outcomes. To address this, tissue engineering strategies combining stem cells with bioactive scaffolds are being intensively explored. Platelet-rich plasma (PRP), a natural concentrate of growth factors, emerges as a promising candidate for enhancing stem cell-based therapies by promoting anabolic activity and mitigating catabolic inflammation. In this study, we developed an injectable, PRP-functionalized hydrogel system using alginate crosslinked with calcium gluconate and calcium chloride. This platform was designed to encapsulate and deliver three-dimensional microcarriers of human umbilical cord mesenchymal stem cells (hucMSCs) pre-cultured on porous microcarriers. Our in vitro experiments demonstrated that this PRP-enriched hydrogel microenvironment significantly enhanced the proliferation ( p < 0.05) and chondrogenic differentiation ( p < 0.01) of hucMSCs, as confirmed by upregulated expression of cartilage-specific markers. Furthermore, in a rat model of knee joint osteochondral defect, the implantation of this composite system markedly facilitated the regeneration of hyaline-like cartilage tissue with improved structural integration and surface smoothness ( p < 0.01). These findings collectively indicate that the synergistic combination of PRP release and three-dimensional stem cell microcarriers within an injectable hydrogel presents a robust and translatable strategy for achieving functional cartilage regeneration.