The Impact of Type 2 Diabetes on the Role of Adipose-Derived Stem Cells in Vasculogenesis
Visakha Suresh, BSE1, Jennifer L. West, PhD2.
1Duke University School of Medicine, Durham, NC, USA, 2Duke University, Durham, NC, USA.
Introduction: Adipose-derived stem cells (ADSCs) have been shown to influence wound healing, however much is unclear about the role these cells play in neovascularization. Previous work has shown that ADSCs may be stimulated to express CD31, an endothelial cell surface marker, using EGM2 media. Understanding the influence of ADSCs on neovascularization may provide novel avenues for stem cell therapy in treating ischemic conditions, such as chronic non-healing wounds seen in diabetic patients. Utilizing three-dimensional in vitro models may provide insight into in vivo cell-cell interactions between ADSCs and vascular endothelial and support cells. Additionally, we sought to understand the influence of a specific ischemia inducing disease state, e.g. type 2 diabetes mellitus, on the role of ADSCs in neovascularization.
Materials and Methods: Using a previously developed 3D cell-adhesive, degradable cell culture matrix consisting of a peptide-modified poly(ethylene-glycol) (PEG) hydrogel, we sought to understand the relationships between human ADSCs and endothelial and pericyte cells through co-culture. ADSCs derived from healthy human donors and ADSCs derived from donors with type 2 diabetes mellitus (abbreviated as D-ADSC) were used in this study. The hydrogels consisted of PEG modified with RGDS, an integrin-binding peptide, and GGGPQGIWGQGK (abbreviated as PQ), a peptide sensitive to enzymatic degradation by matrix-metalloproteinase-2 and 9. Cells were co-cultured in these hydrogels and maintained in EGM2 media for 7 days. The gels were fixed and immunohistochemistry was performed. Metamorph software was used for measuring tubule diameter. Quantification was performed using a one-way ANOVA, where a p-value < 0.05 was considered significant. All values are reported as mean ± standard deviation.
Results: After 7 days, 3D co-culture of ADSCs and human endothelial cells in EGM2 media showed the formation of tubule-like networks (tubule diameter of 12.88 ± 1.50 microns). Tubule diameters in these sets of co-cultures were similar to that seen in the control 3D co-cultures of human endothelial cells and pericytes (12.57 ± 1.30 microns, p = 0.2986). 3D co-culture of D-ADSCs and human endothelial cells also showed the formation of tubule-like networks, with an average tubule diameter of 8.97 ± 1.24 microns. This decrease in tubule diameter was statistically significant compared to the control co-cultures of human endothelial cells and pericytes (p = 0.021).
Conclusions: Our findings suggest that ADSCs do contribute to neovascularization when stimulated in the appropriate environment. Additionally, diabetic ADSCs were found to be less supportive of tubule formation compared to wild type ADSCs.
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