In situ tissue engineering is a powerful strategy for the treatment of bone defects. It could overcome the limitations of traditional bone tissue engineering, which typically involves extensive cell expansion steps, low cell survival rates upon transplantation, and a risk of immuno-rejection. Here, a porous scaffold polycaprolactone (PCL)/decellularized small intestine submucosa (SIS) was fabricated via cryogenic free-form extrusion, followed by surface modification with aptamer and PlGF-2_123-144*-fused BMP2 (pBMP2). The two bioactive molecules were delivered sequentially. The aptamer Apt19s, which exhibited binding affinity to bone marrow-derived mesenchymal stem cells (BMSCs), was quickly released, facilitating the mobilization and recruitment of host BMSCs. BMP2 fused with a PlGF-2_123-144 peptide, which showed “super-affinity” to the ECM matrix, was released in a slow and sustained manner, inducing BMSC osteogenic differentiation. In vitro results showed that the sequential release of PCL/SIS-pBMP2-Apt19s promoted cell migration, proliferation, alkaline phosphatase activity, and mRNA expression of osteogenesis-related genes. The in vivo results demonstrated that the sequential release system of PCL/SIS-pBMP2-Apt19s evidently increased bone formation in rat calvarial critical-sized defects compared to the sequential release system of PCL/SIS-BMP2-Apt19s. Thus, the novel delivery system shows potential as an ideal alternative for achieving cell-free scaffold-based bone regeneration in situ.

Ideal bone tissue engineering scaffolds composed of extracellular matrix (ECM) require excellent osteoconductive ability to imitate the bone environment. We developed a mineralised tissue-derived ECM-modified true bone ceramic (TBC) scaffold for the delivery of aspartic acid-modified bone morphogenic protein-2 (BMP-2) peptide (P28) and assessed its osteogenic capacity. Decellularized ECM from porcine small intestinal submucosa (SIS) was coated onto the surface of TBC, followed by mineralisation modification (mSIS/TBC). P28 was subsequently immobilised onto the scaffolds in the absence of a crosslinker. The alkaline phosphatase activity and other osteogenic differentiation marker results showed that osteogenesis of the P28/mSIS/TBC scaffolds was significantly greater than that of the TBC and mSIS/TBC groups. In addition, to examine the osteoconductive capability of this system in vivo, we established a rat calvarial bone defect model and evaluated the new bone area and new blood vessel density. Histological observation showed that P28/mSIS/TBC exhibited favourable bone regeneration efficacy. This study proposes the use of mSIS/TBC loaded with P28 as a promising osteogenic scaffold for bone tissue engineering applications.

Wounds, a major complication in orthopedic-related diseases, present significant challenges for orthopedic surgeons due to impaired healing driven by vascular dysfunction, oxidative stress, and chronic inflammation. This study introduces an injectable, self-healing, pH-responsive hydrogel system delivering curcumin-preconditioned mesenchymal stem cell (MSC)-derived exosomes (Cur-Exos) to enhance diabetic wound repair, offering a cell-free therapeutic strategy with applications in orthopedic regenerative medicine. The hydrogel, formed through dynamic cross-linking of amphoteric chitosan and multi-armed polyethylene glycol, exhibits antibacterial properties and degrades selectively in the acidic microenvironment (pH 4.5–6.5) of diabetic wounds. Loaded with Cur-Exos, it enables controlled release of bioactive molecules, leveraging the enhanced antioxidant, anti-inflammatory, and pro-angiogenic properties of exosomes from curcumin-preconditioned MSCs. In vitro, Cur-Exo@Gel exhibited excellent biocompatibility, promoted endothelial cell migration, and enhanced angiogenesis, while reducing oxidative stress. It also modulated macrophage polarization by decreasing pro-inflammatory M1 markers (iNOS) via the upregulation of Iκβ-α and reduced p65 phosphorylation, fostering an anti-inflammatory microenvironment. The hydrogel’s inherent antibacterial properties (>50% reduction in Escherichia coli and Staphylococcus aureus, p < 0.05) further mitigate infection risks that are critical in orthopedic wounds. In vivo, in a diabetic rat full-thickness skin defect model, Cur-Exo@Gel significantly reduced wound areas, with enhanced epithelial migration and collagen deposition. These findings highlight Cur-Exo@Gel as a promising cell-free therapeutic strategy for accelerating chronic orthopedic wound repair, offering novel insights for regenerative orthopedics.