Diabetic Adipose Derived Stem Cells Display Functional Impairments in the Setting of a Regenerative Biomimetic Hydrogel Scaffold

Introduction: Diabetes is associated with a reduced neovascular and wound healing potential that may be due in part to impaired stem cell function. Adipose derived mesenchymal stem cells (ASCs) are a clinically appealing source of multipotent progenitor cells that can be applied to wounds to improve neovascularization and accelerate wound healing.^1,2 However, the effect of diabetes on ASC therapeutic function remains unclear. In this study, we examine diabetic ASC behavior and neovascular potential in the setting of a previously established biomimetic hydrogel scaffold,^3-5 in order to better understand the regenerative capacity of these cells.

Methods: ASCs were harvested from wild-type (C57BL/6) and diabetic (db/db) mice, and in vitro angiogenic tubule formation was assessed upon co-culture with endothelial cells. Cell biocompatibility and functionality within a biomimetic hydrogel was analyzed using microscopic evaluation of morphology and quantification of secreted factors associated with neovascularization and tissue remodeling. Finally, the in vivo regenerative potential of diabetic and wild-type ASCs was determined through application of cell-seeded hydrogels to murine ischemic skin flaps.

Results: Diabetic ASCs promoted less endothelial cell tubule formation following in vitro co-culture (16.9 ± 1.6 vs 27. 1 ± 1.6 tubules/HPF, p < 0.01). Upon hydrogel seeding, diabetic cells remained in a clumped pattern and failed to produce cytoplasmic elongations, whereas wild-type ASCs displayed a multidimensional spreading. Moreover, diabetic ASCs displayed a decreased expression of angiogenic and tissue remodeling factors, including VEGF, HGF and MMP-9 (p ≤ 0.03). In accordance with this signaling dysfunction, ischemic flaps treated with diabetic versus wild-type ASCs displayed significantly reduced levels of tissue survival (21.3 %± 8.5 vs 45.1% ± 11.1, p = 0.05).  

Conclusion: Diabetic ASCs display a substantial impairment in therapeutic potential as implicated by deficiencies in secretory profiles, biomimetic hydrogel incorporation and in vivo amelioration of ischemic injury. This data indicates that the utility of autologous ASCs for cell-based therapies in diabetic patients may be limited, warranting the exploration of alternative cell sources or additional interventions to improve cell function before application.