The aim of this study was to develop nanofibrous silk substrates for limbal stem cell expansion that can serve as a potential alternative substrate to replace human amniotic membrane. The human limbal stem cell was used to evaluate the biocompatibility of substrates (random and oriented nanofibrous mats, and human amniotic membrane) based on their phenotypic profile, viability, proliferation, and attachment ability. Biocompatibility results indicated that all substrates were highly biocompatible, as limbal stem cells could favorably attach and proliferate on the nanofibrous surfaces. Microscopic figures showed that the human limbal stem cells were firmly anchored to the substrates and were able to retain a normal corneal stem cell phenotype. Microscopic analyses illustrated that cells infiltrated the nanofibers and successfully formed a three-dimensional corneal epithelium, which was viable for 15 days. Immunocytochemistry and real-time PCR results revealed no change in the expression profile of limbal stem cells grown on nanofibrous substrates when compared to those grown on human amniotic membrane. In addition, electrospun nanofibrous silk substrates especially oriented mat provides not only a milieu supporting limbal stem cells expansion, but also serve as a useful alternative carrier for ocular surface tissue engineering and could be used as an alternative substrate to amniotic membrane.

The aim of this study was to produce a chitosan–cross-linked nanofibrous biodegradable poly (3-hydroxybutyrate-co-3-hydroxyvalerate) nerve conduit. The artificial nerve scaffold designed by electrospinning method and cross-linked with chitosan by chemical method. Afterwards, the scaffolds were evaluated by microscopic, physical, and mechanical analyses and cell culture assays with Schwann cells. The conduits were implanted into a 10 mm gap in the sciatic nerves of the rats. Four months after surgery, the regenerated nerves were evaluated by macroscopic assessments and histology. This polymeric conduit had sufficiently good mechanical properties to serve as a nerve guide. Cellular experiments showed a better cell adhesion, growth, and proliferation inside the cross-linked nanofibrous scaffolds compared with un–cross-linked ones, also Schwann cells well attached on chitosan–cross-linked nanofibrous surface. The in vivo results demonstrated that in the nanofibrous graft, the sciatic nerve trunk had been reconstructed with restoration of nerve continuity and formatted nerve fibers with myelination. This neural conduit appears to have the right organization for testing in vivo nerve tissue engineering studies.

Plant-derived tannic acid as a green material can play an important role in improving the mechanical and physical properties of biomaterials. Tannic acid can be used as an antioxidant, antimicrobial, and cross-linking agent in biomaterial products due to its unique functional groups. Its active phenolic groups can react with biomaterial functional groups to form bonds that improve performance. In this review, the mechanism of effectiveness of tannic acid as a natural crosslinker in improving the properties of biomaterials for various applications, such as tissue engineering, tissue adhesives, drug delivery, wound healing, and toxicity studies, has been investigated. In general, tannic acid can be a suitable alternative to synthetic crosslinkers in biomaterial applications.

A nanofibrous PHBV nerve conduit has been used to evaluate its efficiency based on the promotion of nerve regeneration in rats. The designed conduits were investigated by physical, mechanical and microscopic analyses. The conduits were implanted into a 30-mm gap in the sciatic nerves of the rats. Four months after surgery, the regenerated nerves were evaluated by macroscopic assessments and histology. This polymeric conduit had sufficiently high mechanical properties to serve as a nerve guide. The results demonstrated that in the nanofibrous graft with cells, the sciatic nerve trunk had been reconstructed with restoration of nerve continuity and formatted nerve fibers with myelination. For the grafts especially the nanofibrous conduits with cells, muscle cells of gastrocnemius on the operated side were uniform in their size and structures. This study proves the feasibility of artificial conduit with Schwann cells for nerve regeneration by bridging a longer defect in a rat model.

In this study, we have evaluated the wound-healing effects of unrestricted somatic stem cells loaded in chitosan-cross linked PHBV nanofibrous scaffold, implanted into the full thickness skin defects of rats. Afterwards, the scaffolds were evaluated by structural, microscopic, physical and mechanical assays and cell culture analyses. Defects were treated with the scaffolds without and with USSCs. MTT assay, immunostaining, and wound pathology were performed for groups twenty one days after implantation. SEM images showed the average diameter of about 100 nm for the nanofibrous scaffolds, increasing up to 500 nm after chitosan-crosslinking. Results of physical and mechanical analyses also showed a good resilience and compliance with movement as a skin graft. Cellular experiments showed a better cell adhesion, growth and proliferation inside the cross-linked nanofibrous scaffolds compared to un-cross linked ones. In animal models, all groups, excluding the control group, exhibited the most pronounced effect on wound closure, with the statistically significant improvement in wound healing being seen at post-operative day 21. Histological and immunostaining examinations of healed wounds from all groups, especially the groups treated with stem cells. Thus, the grafting of chitosan-cross-linked nanofibrous scaffold loaded with USSC showed better results during the healing process of skin defects in rat models.

Fish skin grafting as a new skin substitute is currently being used in clinical applications. Acceleration of the wound healing, lack of disease transmission, and low cost of the production process can introduce fish skin as a potential alternative to other grafts. An appropriate decellularization process allows the design of 3D acellular scaffolds for skin regeneration without damaging the morphology and extracellular matrix content. Therefore, the role of decellularization processes is very important to maintain the properties of fish skin. In this review article, recent studies on various decellularization processes as well as biological, physical, and mechanical properties of fish skin and its applications with therapeutic effects in wound healing were investigated.