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Unlabelled: Loss of adipose tissue can occur due to congenital and acquired lipoatrophies, trauma, tumor resection, and chronic disease. Clinically, it is difficult to regenerate or reconstruct adipose tissue. The extensive microvsacular network present in adipose, and the sensitivity of adipocytes to hypoxia, hinder the success of typical tissue transfer procedures. Materials that promote the formation of vascularized adipose tissue may offer alternatives to current clinical treatment options. A number of synthetic and natural biomaterials common in tissue engineering have been investigated as scaffolds for adipose regeneration. While these materials have shown some promise they do not account for the unique extracellular microenvironment of adipose. Adipose derived hydrogels more closely approximate the physical and chemical microenvironment of adipose tissue, promote preadipocyte differentiation and vessel assembly in vitro, and stimulate vascularized adipose formation in vivo. The combination of these materials with techniques that promote rapid and stable vascularization could lead to new techniques for engineering stable, vascularized adipose tissue for clinical application. In this review we discuss materials used for adipose tissue engineering and strategies for vascularization of these scaffolds., Clinical Relevance: Materials that promote formation of vascularized adipose tissue have the potential to serve as alternatives or supplements to existing treatment options, for adipose defects or deficiencies resulting from chronic disease, lipoatrophies, trauma, and tumor resection., (Copyright © 2009 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.)

Interactions with the extracellular matrix (ECM) play an important role in regulating cell function. Cells cultured in, or on, three-dimensional ECM recapitulate similar features to those found in vivo that are not present in traditional two-dimensional culture. In addition, both natural and synthetic materials containing ECM components have shown promise in a number of tissue engineering applications. Current materials available for cell culture and tissue engineering do not adequately reflect the diversity of ECM composition between tissues. In this paper, a method is presented for extracting solutions of proteins and glycoproteins from soft tissues and inducing assembly of these proteins into gels. The extracts contain ECM proteins specific to the tissue source with low levels of intracellular molecules. Gels formed from the tissue-derived extracts have nanostructure similar to ECM in vivo and can be used to culture cells as both a thin substrate coating and a thick gel. This technique could be used to assemble hydrogels with varying composition depending upon the tissue source, hydrogels for three-dimensional culture, as scaffolds for tissue engineering therapies, and to study cell-matrix interactions.

The success of many therapies in regenerative medicine requires the ability to control the formation of stable vascular networks within tissues. The formation of new blood vessels, or neovascularization, is mediated, in part, by interactions between endothelial cells (ECs) and insoluble factors in the extracellular microenvironment. These interactions are determined by the chemical, physical, and mechanical properties of the matrix. Understanding how extracellular matrices (ECMs) and synthetic scaffolds influence neovascularization can contribute to the fundamental knowledge of normal and diseased tissue physiology and can be used to guide the design of new therapies. The goal of this review is to provide an overview of the complex role EC-matrix interactions play in neovascularization. A particular emphasis is placed on presenting differences in two subsets of ECM, basement membranes and stromal matrices, and identification of the properties of these matrices that define their biological functions. Attempts to apply information about EC-ECM interactions to enhance vascularization of synthetic materials are presented, and areas in need of further research are identified throughout this review. Our understanding of the role EC-matrix interactions play in neovascularization remains limited, but continued progress in this area could be of significant benefit to the design of clinically applicable engineered tissues.

A number of pathological entities and surgical interventions could benefit from therapeutic stimulation of new blood vessel formation. Although strategies designed for promoting neovascularization have shown promise in preclinical models, translation to human application has met with limited success when angiogenesis is used as the single therapeutic mechanism. While clinical protocols continue to be optimized, a number of exciting new approaches are being developed. Bioengineering has played an important role in the progress of many of these innovative new strategies. In this review, we present a general outline of therapeutic neovascularization, with an emphasis on investigations using engineering principles to address this vexing clinical problem. In addition, we identify some limitations and suggest areas for future research.