A novel animal model for skin flap prelamination with biomaterials

Fibroblast Growth Factor in Diabetic Foot Ulcer: Progress and Therapeutic Prospects

Diabetic foot ulcer (DFU) is a combination of neuropathy and various degrees of peripheral vasculopathy in diabetic patients resulting in lower extremity infection, ulcer formation, and deep-tissue necrosis. The difficulty of wound healing in diabetic patients is caused by a high glucose environment and various biological factors in the patient. The patients' skin local microenvironment changes and immune chemotactic response dysfunction. Wounds are easy to be damaged and ulcerated repeatedly, but difficult to heal, and eventually develop into chronic ulcers. DFU is a complex biological process in which many cells interact with each other. A variety of growth factors released from wounds are necessary for coordination and promotion of healing. Fibroblast growth factor (FGF) is a family of cell signaling proteins, which can mediate various processes such as angiogenesis, wound healing, metabolic regulation and embryonic development through its specific receptors. FGF can stimulate angiogenesis and proliferation of fibroblasts, and it is a powerful angiogenesis factor. Twenty-three subtypes have been identified and divided into seven subfamilies. Traditional treatments for DFU can only remove necrotic tissue, delay disease progression, and have a limited ability to repair wounds. In recent years, with the increasing understanding of the function of FGF, more and more researchers have been applying FGF-1, FGF-2, FGF-4, FGF-7, FGF-21 and FGF-23 topically to DFU with good therapeutic effects. This review elaborates on the recently developed FGF family members, outlining their mechanisms of action, and describing their potential therapeutics in DFU.

Vascularization strategies for skin tissue engineering

Lack of proper vascularization after skin trauma causes delayed wound healing. This has sparked the development of various tissue engineering strategies to improve vascularization.

Construction of a dermis-fat composite in vivo: Optimizing heterogeneous acellular dermal matrix with in vitro pretreatment

Dermis-fat composite tissues have been widely used in plastic and reconstructive surgery and were previously constructed using hydrogel-type scaffolds. The constructs can be used for in vitro cosmetic and pharmaceutical testing but are not mechanically strong enough for in vivo applications. In this study, we used heterogeneous (porcine) acellular dermal matrix (PADM) as dermal layer scaffold. PADM was pretreated with the laser micropore technique and then precultured with rat adipose-derived stem cells (rADSCs) in vitro. rADSCs proliferated well on pretreated/unpretreated PADM, showing increased expression of genes associated with inflammatory regulation, proangiogenesis, and stemness, indicating that pretreated/unpretreated PADM both provide a beneficial microenvironment for rADSCs to exert their paracrine function. After in vitro processing, the rADSCs-polyporous PADM and PADM without pretreatments were implanted into the back of rats respectively, followed by adipose tissue transplantation. After implantation, the inflammation induced by pretreated PADM was significantly attenuated and localized compared to the unpretreated group. Moreover, the vascularization was faster, and more adipose tissue was formed in the pretreated group. Sound dermis-fat composite tissue was constructed with sufficient strength, which can potentially be used for actual repair application.

Pre-culture of adipose-derived stem cells and heterologous acellular dermal matrix: paracrine functions promote post-implantation neovascularization and attenuate inflammatory response

Heterologous acellular dermal matrix (ADM) has good biocompatibility and sufficient strength for clinical use for the repair of defects, tissue filling, and resurfacing of deep wounds. However, ADM tissue has such a compact structure that it can easily result in delayed vascularization after implantation. Moreover, in spite of the low immunogenicity of heterologous ADM, it can still cause varying degrees of inflammation in the host. These two drawbacks limit the efficacy and scope of clinical applications for heterologous ADM. Adipose-derived stem cells (ADSCs) have multiple effects on promoting vascularization and regulating immunological responses through paracrine signaling. Pre-culturing heterologous ADM with ADSCs may address these problems; however, it is unknown if ADSCs can exert their paracrine functions within a heterologous ADM microenvironment. This study examined the effect of porcine ADM (PADM) on the paracrine function of rat ADSCs (rADSCs) and showed that the expression of genes associated with inflammatory regulation, pro-angiogenesis factors, and stemness increased when rADSCs were seeded on PADM compared to rADSCs seeded on microplates. This indicates that PADM can provide a beneficial microenvironment for ADSCs to exert their paracrine function. After pre-culture, in vivo implanted rADSC-PADM exhibited improved vascularization and mitigated inflammatory response compared to untreated PADM. This study is the first to report that ADM can provide a suitable microenvironment for ADSCs and that pre-culturing improved the ADM implantation quality in vivo. These results suggest that it could be possible to apply heterologous ADM more effectively and broadly for repair and reconstruction treatments.