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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]

Abstract: Microvascular network formation is required for the success of many therapies in regenerative medicine. The process of vessel assembly is fundamentally altered, however, in many people within the potential patient population, including the elderly and people with diabetes. Significant research has been performed to determine how cellular dysfunction contributes to this inadequate neovascularization, but alterations in the extracellular matrix (ECM) may also influence this process. Glycation of ECM proteins, specifically type I collagen, increases as people age and is accelerated due to uncontrolled diabetes. This glycation results in increased ECM stiffness and resistance to degradation. The goal of this research is to determine whether collagen glycation consistent with changes in aged (defined as people older than 80 years old) and diabetic individuals influences neovascularization. Collagen gels that were incubated in glucose-6-phopshate (G6P) for varying times exhibited cross-linking (26.2±8.1% and 31.3±5.6% for incubation in 375 mM G6P for 5 and 8 days, respectively), autofluorescence, and advanced glycation end product levels (666±481 and 2122±501 pmol/mg protein for 5 and 8 days of 375 mM G6P, respectively) consistent with aged and diabetic populations. Three-dimensional culture models showed that sprouting angiogenesis was delayed in collagen gels with high levels of glycation. When implanted in vivo, glycated gels were degraded (44.4±4.2% and 49.5±11.7% nondegraded gel remaining for gels incubated for 5 and 8 days in 375 mM G6P, respectively) and vascularized (75.5±32.0 and 73.7±23.6 vessels/mm2) more slowly than controls (22.3±9.9% gel remaining and 133.3±31.0 vessels/mm2). These results suggest that glycation of collagen can alter neovascularization and may contribute to alterations in vessel assembly observed as people age and due to diabetes. [Copyright &y& Elsevier]