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Biomaterials that support adipogenesis could contribute to tissue engineering therapies to be used as alternatives to traditional methods of tissue reconstruction and regeneration. We have recently shown that hydrogels comprised of urea soluble proteins and polysaccharides extracted from adipose tissue promote preadipocyte differentiation in vitro and adipogenesis in vivo. However, it is not clear if these findings result from the adipose tissue source of the extracts or if the technique isolates adipogenic factors from other tissues. The present study investigates whether the application of this technique to dermis samples would provide adipogenic hydrogels. Extracts from dermis assembled into hydrogels by either temperature or pH mechanisms. Both formulations supported preadipocyte differentiation in vitro and vascularized adipose formation in vivo. The temperature formulation of the gels induced more rapid adipose formation than the pH formulation in vivo. Interestingly, in comparison to our previous studies the dermis derived hydrogels had comparable adipogenic properties to adipose gels in vivo but not in vitro. Further study of these materials could lead to insight of the role of specific matrix properties on adipogenesis., ((c) 2009 Wiley Periodicals, Inc.)

Abstract: 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 &y& Elsevier]

Abstract: Biomaterials that induce adipogenesis may ultimately serve as alternatives to traditional tissue reconstruction and regeneration techniques. In addition, these materials can provide environments for studying factors that regulate adipogenesis. The present study investigates the potential of adipose-derived matrices to induce adipogenesis in vitro and in vivo. Solutions containing basement membrane proteins and growth factors were extracted from subcutaneous adipose tissue. These extracts could be induced to form gels by either incubating the solutions at 37°C or adjusting the pH to 4.0. The adipose extracts promoted rapid preadipocyte aggregation and formation of lipid-loaded colonies in vitro. Differentiation on adipose-derived gels was greater than tissue culture dishes and the tumor-derived product Matrigel™ (p <0.05). Significant adipose formation was observed when adipose-derived gels were implanted around a rat epigastric pedicle bundle. Adipose levels in these gels were significantly greater than Matrigel™ (p <0.05). The duration of adipose formation depended on the mechanism for gelling the solutions, with acid gelled matrices having greater adipose levels at 6 weeks than temperature gelled matrices. These adipose-derived hydrogels promote rapid adipogenesis in vitro and in vivo. They may lead to new materials for adipose tissue engineering, and provide an environment for studying cell–matrix interactions in adipogenesis. [Copyright &y& Elsevier]