De novo vascularization of implantable tissue and whole organ constructs has been a significant challenge in the field of tissue engineering; the use of endothelial cell populations for this task is constrained by the cell population's limited regeneration capacity and potential for loss of function. Thus, there is a need for a stem-cell population that may be induced into an endothelial cell phenotype reliably. Adipose derived stem cells (ADSCs) are multipotent cells that can be readily isolated from donor fat and may have the potential to be readily induced into endothelial cells. The ability to stimulate endothelial differentiation of these cells has been limited in standard 2D culture. We hypothesized that 3D culture would yield better differentiation. To study the influence of cell density and culture conditions on the potential of ADSCs to differentiate into an endothelial-like state, we seeded these cells types within a 3D cell-adhesive, proteolytically degradable, peptide-modified poly(ethylene-glycol) (PEG) hydrogel. ADSCs were either cultured in basal media or pro-angiogenic media supplemented with 20 ng/mL of VEGF in 2D and then encapsulated at low or high densities within the PEG-based hydrogel. These encapsulated cells were maintained in either basal media or pro-angiogenic media. Cells were then isolated from the hydrogels and cultured in Matrigel to assess the potential for tubule formation. Our work shows that maintenance of ADSCs in a pro-angiogenic medium in 2D monoculture alone does not result in any CD31 expression. Furthermore, the level of CD31 expression was affected by the density of the cells encapsulated within the PEG-based hydrogel. Upon isolation of these cells, we found that these induced ADSCs were able to form tubules within Matrigel, indicative of endothelial function, while ADSCs cultured in basal medium could not. This finding points to the potential for this stem-cell population to serve as a safe and reliable source of endothelial cells for tissue engineering and regenerative medicine purposes.

中文翻译：

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3D培养可促进VEGF刺激的脂肪干细胞的内皮细胞分化。

可植入组织和整个器官构造的新生血管形成一直是组织工程领域的重大挑战。内皮细胞群用于此任务的使用受到细胞群有限的再生能力和功能丧失的潜力的限制。因此，需要可以可靠地诱导为内皮细胞表型的干细胞群体。脂肪衍生干细胞（ADSC）是多能干细胞，可以很容易地从供体脂肪中分离出来，并且有可能容易被诱导为内皮细胞。在标准2D培养中，刺激这些细胞内皮分化的能力受到限制。我们假设3D文化将产生更好的分化。为了研究细胞密度和培养条件对ADSCs分化为内皮样状态的潜力的影响，我们将这些细胞类型植入了3D细胞粘附，可蛋白水解降解的，肽修饰的聚乙二醇（PEG）中）水凝胶。将ADSCs在补充了20 ng / mL VEGF的二维基础培养基或促血管生成培养基中培养，然后以低密度或高密度封装在基于PEG的水凝胶中。这些包封的细胞维持在基础培养基或促血管生成培养基中。然后从水凝胶中分离细胞，并在基质胶中培养以评估肾小管形成的潜力。我们的工作表明，仅在2D单培养中在促血管生成培养基中维持ADSC不会导致任何CD31表达。此外，CD31表达的水平受PEG基水凝胶中封装的细胞密度的影响。分离这些细胞后，我们发现这些诱导的ADSC能够在基质胶内形成小管，表明内皮功能，而在基础培养基中培养的ADSC则不能。这一发现表明，该干细胞群体有可能用作组织工程和再生医学目的的安全可靠的内皮细胞来源。