A Preexisting Microvascular Network Benefits In Vivo Revascularization of a Microvascularized Tissue-Engineered Skin Substitute

Abstract

Delayed or absence of vascularization is one of the major reasons for skin engraftment failure in patients with extensive burns. For such trauma victims, the best alternative to a split-thickness graft would be wound coverage with an autologous in vitro reconstructed skin (RS) combining dermis and epidermis with an appropriate microvascularization. We have developed an endothelialized RS based on our self-assembly approach, which is generated from autologous cultured cells without any exogenous angiogenic growth factor or scaffold. After transplantation in athymic mice, an early inosculation between the graft and host vasculatures occurred within 4 days. We also concurrently detected an active invasion of the dermis by host capillaries sprouting from the wound bed. Thus, the microvascular network constructed in vitro within our three-dimensional skin substitute did not only develop functional anastomoses with the host's blood vessels but also promoted a rapid, complete, and optimal vascularization of the implanted tissues by exerting an angiogenic effect compared with control RS. Our model may bring about interesting possibilities for regenerative medicine by leading to faster vascularization in clinical applications. In addition, the endothelialized RS can be a useful in vitro angiogenesis model.

A first vascularized skin equivalent for as an alternative to animal experimentation

“…Also, the matrix provides stable vessel lumen, allowing the perfusion of the complex vascular network formed. To date, perfusion of vessel-like structures in pre-vascularized models has only been achieved upon grafting to an animal model (Gibot et al, 2010;Schechner et al, 2003;Tremblay et al, 2005). The current model can be regarded as an improvement on a previously published pre-vascularized skin model, which only enabled medium flow underneath the tissue and left out the perfusion of vessels in the construct (Helmedag et al, 2015).…”

Control of Perfusable Microvascular Network Morphology Using a Multiculture Microfluidic System

“…It has been increasingly realized that forming prevascularized tissue in vitro may be a necessary first step. 15,28,29 Additionally, in vitro platforms enabling the growth and maintenance of a functional microvasculature provide significant benefits in their own right. Perfusable, in vitro models can be used as physiological drug-screening platforms for developing and identifying metastasis preventing cancer drugs.…”

The Effects of Constant Flow Bioreactor Cultivation and Keratinocyte Seeding Densities on Prevascularized Organotypic Skin Grafts Based on a Fibrin Scaffold

“…Fibroblasts play an important role in organizing the clot, which includes the secretion of extracellular matrix and the promotion of angiogenesis. 14,15 To our knowledge, bi-layered prevascularized skin grafts so far have been only engineered based on the so-called ''self-assembly approach,'' [16][17][18] collagenbased scaffolds, 19,20 de-cellularized donor dermis, 21 or use of a de-cellularized porcine jejunal segment as suggested by Groeber et al 22 All of these methods are characterized by specific shortcomings: The self-assembly approach takes approximately 6 weeks to form a prevascularized neo-dermis, which is a significantly longer timeframe than our employed method. Collagen-based scaffolds, de-cellularized donor dermis, or xenogenous templates cannot offer a complete autologous approach; drawbacks such as transmission of infectious diseases, allergic reactions, or intricate experimental setup have to be taken into account as a possible future issue regarding human implementation.…”