Engineered muscle from micro-channeled PEG scaffold with magnetic Fe3O4 fixation towards accelerating esophageal muscle repair

Bioprinted biomimetic hydrogel matrices guiding stem cell aggregates for enhanced chondrogenesis and cartilage regeneration

Articular cartilage tissue has limited self-repair capabilities, with damage frequently progressing to irreversible degeneration. Engineered tissues constructed through bioprinting and embedded with stem cell aggregates offer promising therapeutic alternatives. Aggregates of bone marrow mesenchymal stromal cells (BMSCs) demonstrate enhanced and more rapid chondrogenic differentiation than isolated cells, thus facilitating cartilage repair. However, it remains a key challenge to precisely control biochemical microenvironments to regulate cellular adhesion and cohesion within bioprinted matrices simultaneously. Herein, this work reports a bioprintable hydrogel matrix with high cellular adhesion and aggregation properties for cartilage repair. The hydrogel comprises an enhanced cell-adhesive gelatin methacrylate and a cell-cohesive chitosan methacrylate (CHMA), both of which are subjected to photo-initiated crosslinking. By precisely adjusting the CHMA content, the mechanical stability and biochemical cues of the hydrogels are finely tuned to promote cellular aggregation, chondrogenic differentiation and cartilage repair implantation. Multi-layer constructs encapsulated with BMSCs, with high cell viability reaching 91.1%, are bioprinted and photo-crosslinked to support chondrogenic differentiation for 21 days. BMSCs rapidly form aggregates and display efficient chondrogenic differentiation both on the hydrogels and within bioprinted constructs, as evidenced by the upregulated expression of Sox9, Aggrecan and Collagen 2a1 genes, along with high protein levels. Transplantation of these BMSC-laden bioprinted hydrogels into cartilaginous defects demonstrates effective hyaline cartilage repair. Overall, this cell-responsive hydrogel scaffold holds immense promise for applications in cartilage tissue engineering.

Slightly photo-crosslinked chitosan/silk fibroin hydrogel adhesives with hemostasis and anti-inflammation for pro-healing cyclophosphamide-induced hemorrhagic cystitis

Cyclophosphamide is commonly used in the treatment of various cancers and autoimmune diseases, while concurrently imposing substantial toxicity on the bladder, frequently manifesting hemorrhagic cystitis. Intravesical interventions, such as hyaluronic acid supplementation, present a therapeutic strategy to reinstate bladder barrier function and alleviate the effects of metabolic toxicants. However, it remains a great challenge to achieve efficient cyclophosphamide-induced hemorrhagic cystitis (CHC) management with accelerated tissue repair owing to the low wet-adhesion, poor hemostasis, and acute inflammatory responses. To address these issues, a hemostatic and anti-inflammatory hydrogel adhesive of chitosan methylacryloyl/silk fibroin methylacryloyl (CHMA/SFMA) is developed for promoting the healing of CHC. The obtained hydrogels show a high adhesive strength of 26.21 N/m with porcine bladder, facilitating the rapid hemostasis within 15 s, and reinstate bladder barrier function. Moreover, this hydrogel adhesive promotes the proliferation and aggregation of SV-HUC-1 and regulates macrophage polarization. Implanting the hydrogels into CHC bladders of a SD rat model, they not only can be completely biodegraded in 14 days, but also effectively control hematuria and inflammation, and accelerate angiogenesis, thereby significantly promote the healing of bladder injury. Overall, CHMA/SFMA hydrogels exhibit rapid hemostasis for treating CHC and accelerate muscle tissue repair via angiogenesis and inflammation amelioration, which may provide a new path for managing severe hemorrhagic cystitis in the clinics.