Epidermis recreation in spongy-like hydrogels: New opportunities to explore epidermis-like analogues

[Excerpt] On the road to successfully achieving skin regeneration, 3D matrices/scaffolds that provide the adequate physico-chemical and biological cues to recreate the ideal healing environment are believed to be a key element [1], [2] and [3]. Numerous polymeric matrices derived from both natural [4] and [5] and synthetic [6], [7] and [8] sources have been used as cellular supports; nowadays, fewer matrices are simple carriers, and more and more are ECM analogues that can actively participate in the healing process. Therefore, the attractive characteristics of hydrogels, such as high water content, tunable elasticity and facilitated mass transportation, have made them excellent materials to mimic cells’ native environment [9]. Moreover, their hygroscopic nature [10] and possibility of attaining soft tissues-like mechanical properties mean they have potential for exploitation as wound healing promoters [11], [12], [13] and [14]. Nonetheless, hydrogels lack natural cell adhesion sites [15], which limits the maximization of their potential in the recreation of the cell niche. This issue has been tackled through the use of a range of sophisticated approaches to decorate the hydrogels with adhesion sequences such as arginine-glycine-aspartic acid (RGD) derived from fibronectin [16], [17] and [18], and tyrosine-isoleucine-glycine-serine-arginine (YIGSR) derived from laminin [18] and [19], which not only aim to modulate cell adhesion, but also influencing cell fate and survival [18]. Nonetheless, its widespread use is still limited by significant costs associated with the use of recombinant bioactive molecules

Wound dressings for a proteolytic-rich environment

Wound dressings have experienced continuous and significant changes over the years based on the knowledge of the biochemical events associated with chronic wounds. The development goes from natural materials used to just cover and conceal the wound to interactive materials that can facilitate the healing process, addressing specific issues in non-healing wounds. These new types of dressings often relate with the proteolytic wound environment and the bacteria load to enhance the healing. Recently, the wound dressing research is focusing on the replacement of synthetic polymers by natural protein materials to delivery bioactive agents to the wounds. This article provides an overview on the novel protein-based wound dressings such as silk fibroin keratin and elastin. The improved properties of these dressings, like the release of antibiotics and growth factors, are discussed. The different types of wounds and the effective parameters of healing process will be reviewed

A new model for preclinical testing of dermal substitutes for human skin reconstruction

BACKGROUND: Currently, acellular dermal substitutes used for skin reconstruction are usually covered with split-thickness skin grafts. The goal of this study was to develop an animal model in which such dermal substitutes can be tested under standardized conditions using a bioengineered dermo-epidermal skin graft for coverage. METHODS: Bioengineered grafts consisting of collagen type I hydrogels with incorporated human fibroblasts and human keratinocytes seeded on these gels were produced. Two different dermal substitutes, namely Matriderm(®), and an acellular collagen type I hydrogel, were applied onto full-thickness skin wounds created on the back of immuno-incompetent rats. As control, no dermal substitute was used. As coverage for the dermal substitutes either the bioengineered grafts were used, or, as controls, human split-thickness skin or neonatal rat epidermis were used. Grafts were excised 21 days post-transplantation. Histology and immunofluorescence was performed to investigate survival, epidermis formation, and vascularization of the grafts. RESULTS: The bioengineered grafts survived on all tested dermal substitutes. Epidermis formation and vascularization were comparable to the controls. CONCLUSION: We could successfully use human bioengineered grafts to test different dermal substitutes. This novel model can be used to investigate newly designed dermal substitutes in detail and in a standardized way

memo - Magazine of European Medical Oncology / Extravasation emergencies : state-of-the-art management and progress in clinical research

In cancer treatment, extravasation is defined as an inadvertent instillation or leakage of cytotoxic drugs into the perivascular space during infusion. As a dreaded complication of chemotherapy, extravasation has gained increasing attention in recent years. Classified according to their subcutaneous toxicity, three types of cytotoxins have been established: vesicants, irritants and nonvesicant drugs. Vesicant cytotoxic drugs may induce tissue damage, ulceration and tissue necrosis. Although we have established measures to manage extravasation emergencies, prevention is of paramount importance. This may be achieved within hospitals through regular training and education, which is best provided by a specialised and experienced task force including all disciplines involved in cancer therapy. Moreover, clinical and translational studies contribute to a better management of chemotherapy-induced extravasation as shown by our group in recent years. We were able to demonstrate that the evaluation of blood flow by indocyanine green angiography in the extravasation area predicts the extent of damage and the need of future surgical intervention. When a Port-a-Cath® extravasation is detected early, a subcutaneous wash-out procedure was found to be beneficial, corroborated by the analytical evaluation of the removed cytotoxic compound epirubicin. In another study, the tissue distribution of platinum was quantified at the anatomic level in cryosections of various tissues. This novel knowledge complements and supports our current efforts to handle extravasations better. On the other hand, a number of new drugs (chemotherapy, monoclonal antibodies, checkpoint inhibitors etc.) with many open issues to reliably classify their tissue toxicity still require our attention.(VLID)349711