Articular cartilage repair remains a major clinical challenge due to the limited regenerative capacity of the tissue and the poor therapeutic efficacy of current treatments. Although stem cell–based therapies hold promise, their clinical outcomes are often compromised by insufficient chondrogenic differentiation, phenotypic instability, and rapid cell loss in the dynamic joint environment. Herein, we report an ultrasound-responsive, bio-scaffold system (e-BMSCs/Gel) designed to enhance cartilage regeneration through coordinated biochemical and genetic regulation. In this system, bone marrow mesenchymal stem cells (BMSCs) are engineered by internalizing nanobubbles (NBs) loaded with TGF-β3 protein and CRISPR/Cas9 plasmids targeting the YAP (pCas9-YAP), termed T@NBspDNA. Additionally, to enhance cell retention and survival, engineered BMSCs (e-BMSCs) are encapsulated within a thermosensitive thiolated-chitosan/hydroxyapatite hydrogel that rapidly forms in situ. Under US stimulation, the synchronized activation of TGF-β3 release and YAP gene silencing significantly promoted the chondrogenic differentiation of e-BMSCs. Furthermore, in vivo evaluation in a rat articular cartilage defect model demonstrates that US-activated e-BMSCs/Gel effectively promotes hyaline-like cartilage regeneration and improves structural restoration of the defect site. Overall, this work presents a controllable bio-scaffold platform, offering a novel strategy for effective cartilage regeneration.
Thermoresponsive injectable hydrogels are promising platforms for soft tissue repair because they enable minimally invasive administration and undergo sol–gel transition under physiological conditions. In this study, methylcellulose-based hydrogels were prepared using sodium sulfate as a thermogelation-promoting agent and functionalized with thiolated hyaluronic acid (HA-SH) and a β-cyclodextrin/curcumin (β-CD/CUR) inclusion complex. The β-CD/CUR complex improved curcumin compatibility and dispersion within the aqueous hydrogel matrix. All formulations exhibited shear-thinning behavior, supporting injectability, while qualitative self-healing tests showed recovery of structural continuity after mechanical disruption. HA-SH incorporation altered the hydration and porous structure, increasing water uptake while reducing porosity. CUR-loaded hydrogels provided sustained curcumin release under physiological conditions, reaching 67.94 ± 6.52% after 24 h for MC3.5/1.5–HA0.25/CUR0.5, with diffusion modeling indicating a diffusion-controlled mechanism. The released curcumin retained antioxidant activity, with the highest DPPH radical scavenging observed at the highest CUR loading. All hydrogels were cytocompatible with normal human fibroblasts, maintaining viability above 80% throughout the study and exceeding 100% after 72 h. CUR-loaded formulations also showed antibacterial activity against Staphylococcus aureus and Escherichia coli, with MC3.5/1.5–HA0.25/CUR0.5 exhibiting the strongest effect. IL-1β analysis showed no pronounced pro-inflammatory response, while CUR-loaded hydrogels reduced LPS-induced IL-1β secretion over time. Scratch assays further demonstrated enhanced fibroblast-mediated wound closure, particularly after 24 and 48 h. Overall, these HA-SH/CUR-loaded thermoresponsive hydrogels combine injectability, cytocompatibility, controlled release, antioxidant and antibacterial activity, and wound closure-supporting properties, highlighting their potential as bioactive platforms for various biomedical applications.
Purpose Carbon dots (CDs) are emerging bioactive nanomaterials for tissue engineering applications. This study aimed to reproduce softwood lignin-derived carbon dots (LCDs) and nitrogen-doped LCDs (N@LCDs) and evaluate their effects on early human adipose-derived mesenchymal stem cell (hMSC) behavior in 2D monolayer and 3D culture systems. Methods LCDs/N@LCDs were reproduced and characterized. CDs were ultrasonically sprayed onto 2D substrates and polyethylenimine (PEI)-treated electrospun poly(lactic-co-glycolic acid) (PLGA, 65:35) 3D scaffolds for in vitro analyses. Distribution after drop-casting and ultrasonic spray deposition (USD) was quantified using nearest-neighbor distance (NND). Native versus cell media-exposed LCD/N@LCD functionalities were compared by Fourier-transform infrared spectroscopy (FTIR). Scaffolds were characterized for structural and compositional properties. Cell attachment, morphology, and biomarker expression were evaluated. Results USD reduced LCD/N@LCD concentration of short NND relative to drop-casting. Following media exposure, LCD/N@LCDs exhibited unique changes in FTIR spectra, supporting distinct media-associated interfacial functionalities. The F-actin aspect ratio differed among groups. (p = 0.0287); LCD/N@LCD increased hMSC elongation relative to control (p = 0.0587 and 0.0371, respectively). 2D cultures showed increased fibronectin-182, MAP2, and GFAP in LCD/N@LCD groups (p < 0.05) compared to untreated substrates. Compared to untreated scaffolds, hMSCs on N@LCD-treated scaffolds displayed increased vinculin (p = 0.015), MAP2 (p = 0.032), GFAP (p > 0.05), and CD31 expression (p = 0.044). Collagen type I and fibronectin-182 increased on LCD/N@LCD-treated scaffolds (p > 0.05). Conclusion LCDs/N@LCDs regulate early hMSC cytoskeletal organization and biomarker expression. Exposure of LCDs/N@LCDs to the biological media exhibited variations in FTIR spectra, suggesting differences in adsorbed proteins, potentially consequential of variant corona composition. Results demonstrate LCD/N@LCDs functioning as bioactive cues, supporting their potential in tissue engineering applications.
Full-thickness skin defects caused by trauma or surgical resection pose a major clinical challenge in wound repair. Effective healing requires early stable structural support and sustained biochemical regulation. Accordingly, developing dynamically tunable scaffolds that meet stage-specific repair requirements is vital for tissue regeneration. In this work, a retinoic acid (RA)-functionalized PCL scaffold was fabricated using melt electrowriting (MEW). The MEW process produced highly ordered microfibers with a diameter of approximately 15 μm and an interfiber spacing of 200 μm. After surface amination, RA was covalently grafted onto PCL-NH₂ via EDC-mediated activation of its carboxyl group, forming an amide bond. During the early repair phase, the ordered microfibers promoted cell adhesion and migration. Upon immersion in PBS, the functionalized interface gradually evolved, enabling low initial RA release followed by sustained release that provided biochemical regulation at later stages. Transcriptomic analysis revealed differential gene expression and alternative splicing-associated changes involving pathways related to cell adhesion, migration, cytoskeletal remodeling, and inflammatory regulation. In a rat full-thickness skin defect model, the PCL-RA scaffold achieved approximately twofold higher repair efficiency than the blank control group and promoted epithelialization and organized collagen remodeling. This study demonstrates that the PCL-RA scaffold can effectively support early structural guidance and subsequent biochemical regulation, offering a novel scaffold design strategy for full-thickness skin defect repair.
