Neural tissue engineering (NTE) has made remarkable strides in recent years and holds great promise for treating several devastating neurological disorders. Selecting optimal scaffolding material is crucial for NET design strategies that enable neural and non-neural cell differentiation and axonal growth. Collagen is extensively employed in NTE applications due to the inherent resistance of the nervous system against regeneration, functionalized with neurotrophic factors, antagonists of neural growth inhibitors, and other neural growth-promoting agents. Recent advancements in integrating collagen with manufacturing strategies, such as scaffolding, electrospinning, and 3D bioprinting, provide localized trophic support, guide cell alignment, and protect neural cells from immune activity. This review categorises and analyses collagen-based processing techniques investigated for neural-specific applications, highlighting their strengths and weaknesses in repair, regeneration, and recovery. We also evaluate the potential prospects and challenges of using collagen-based biomaterials in NTE. Overall, this review offers a comprehensive and systematic framework for the rational evaluation and applications of collagen in NTE.

Background: Osteoarthritis (OA) is characterized by inflammation and extracellular matrix (ECM) degradation and is one of the most common chronic degenerative joint diseases that causes pain and disability in adults. Urolithin A (UA) has been widely reported for its anti-inflammatory properties in several chronic diseases. However, the effects of UA on OA remain unclear. The aim of the current study was to investigate the anti-inflammatory effects and mechanism of UA in interleukin-1β (IL-1β)-induced chondrocytes. Results: No marked UA cytotoxicity was noted, and UA protected cartilage from damage following IL-1β stimulation in micromasses. Moreover, UA promoted the expression of anabolic factors including Sox-9, Collagen II, and Aggrecan while inhibiting the expression of catabolic factors such as matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS-4) in rat chondrocytes. Protective effects of UA were also observed in ex vivo organ culture of articular cartilage. Mechanistically, IL-1β significantly activated and upregulated the expression of p-ERK 1/2, p-JNK, p-P38, and p-P65, while UA protected chondrocytes against IL-1β-induced injury by activating the mitogen-activated kinase (MAPK)/nuclear factor-κB (NF-κB) signaling pathways. Conclusion: Our results provide the evidence that UA could attenuate IL-1β-induced cell injury in chondrocytes via its anti-inflammatory action. UA may be a promising therapeutic agent in the treatment of OA.

Recently, regenerated silk fibroin is one of the most investigated silk-based materials for tissue engineering. However, it needs complex preparation process and will irresistibly denature to solid state with time, which is the biggest challenge to produce in large scale and widely use it as commercial material. In this work, industrially produced sericin, silk fibroin amino acid, and silk fibroin powder were investigated on its physico–chemical and biological properties compared with laboratory prepared regenerated silk fibroin, in order to excavate the potential application in biomedical and therapeutical fields. The results showed that sericin may be the most suitable silk materials to use as an alternative in tissue engineering compared with regenerated silk fibroin. It was found that sericin can absorb UV in the range of 223–300 nm, inhibit tyrosinase, resist to free radicals, and retain water capacity similar to hyaluronic acid. Importantly, cell experiment on human fibroblast showed that sericin (0.05 wt%) could stimulate cell proliferation and obviously up-regulate the expression of collagen type I, collagen type III, and hyaluronidase I compared with the control at seven days, which is the closest equivalent to regenerated silk fibroin. These results suggested that sericin might be a valuable ingredient for skin repair on tissue engineering.