Unique Responses of Stem Cell-Derived Vascular Endothelial and Mesenchymal Cells to High Levels of Glucose

Abstract

Diabetes leads to complications in selected organ systems, and vascular endothelial cell (EC) dysfunction and loss is the key initiating and perpetuating step in the development of these complications. Experimental and clinical studies have shown that hyperglycemia leads to EC dysfunction in diabetes. Vascular stem cells that give rise to endothelial progenitor cells (EPCs) and mesenchymal progenitor cells (MPCs) represent an attractive target for cell therapy for diabetic patients. Whether these vascular stem/progenitor cells succumb to the adverse effects of high glucose remains unknown. We sought to determine whether adult vascular stem/progenitor cells display cellular activation and dysfunction upon exposure to high levels of glucose as seen in diabetic complications. Mononuclear cell fraction was prepared from adult blood and bone marrow. EPCs and MPCs were derived, characterized, and exposed to either normal glucose (5 mmol/L) or high glucose levels (25 mmol/L). We then assayed for cell activity and molecular changes following both acute and chronic exposure to high glucose. Our results show that high levels of glucose do not alter the derivation of either EPCs or MPCs. The adult blood-derived EPCs were also resistant to the effects of glucose in terms of growth. Acute exposure to high glucose levels increased caspase-3 activity in EPCs (1.4x increase) and mature ECs (2.3x increase). Interestingly, MPCs showed a transient reduction in growth upon glucose challenge. Our results also show that glucose skews the differentiation of MPCs towards the adipocyte lineage while suppressing other mesenchymal lineages. In summary, our studies show that EPCs are resistant to the effects of high levels of glucose, even following chronic exposure. The findings further show that hyperglycemia may have detrimental effects on the MPCs, causing reduced growth and altering the differentiation potential.

TSPO ligand residence time influences human glioblastoma multiforme cell death/life balance

“…Specifically, cell number was determined using Trypan blue dye exclusion assay and Scepter 2.0 Automated Cell Counter (Millipore) as previously described [47]. The colorimetric assay utilizing MTS reagent was used to establish the PIGA concentration that inhibited 50 % (IC 50 value) of U87MG cell survival after 24 h of treatment and was performed according to the manufacturer's instructions.…”

Pathophysiological role of enhanced bone marrow adipogenesis in diabetic complications

“…31,36 These stem cells can be distinguished from hematopoietic stem cells by their ability to differentiate into endothelial and mural lineages and to regenerate functional vessels. 7,36,37 Studies have also shown that diabetes leads to reduced mobilization of stem cells from the marrow. 38,39 A number of signaling mechanisms have been identified underlying this abnormality.…”

“…And finally, we have shown that high levels of glucose decrease endothelial and mesenchymal progenitor cell numbers acutely (within 24 h of culture). 37 However, cells recover from glucose toxicity with sustained exposure. In addition, the differentiation capacity of blood and bone marrow-derived stem cells to produce endothelial and mesenchymal progenitor cells is not altered by the presence of high levels of glucose.…”

“…42 In addition, we have shown specific induction of PPARg2 in human marrow MPCs following addition of adipogenic differentiation media and the levels parallel C/EBPa. 36,37 Therefore, examining the expression of these transcription factors offer insight into paracrine factors regulating adipogenesis in diabetes.…”

Isolation, expansion and differentiation of mesenchymal stromal cells from rabbits' bone marrow

“…However, studies have shown that high glucose concentrations can impair original cellular functions such as apoptosis, viability and proliferation; besides, it can change the ability of primary cells in forming colonies in vitro and in vivo, regardless of their origin tissue (Li et al 2007). High glucose concentrations may also modify the gene expression and direct the differentiation of stem cells to the adipogenic over the chondrogenic and osteogenic lineages (Kearts & Khan 2012). On the other hand, glucose depletion improves these properties due to the overall beneficial effects already described of caloric restriction for stem cells, such as delay of cell death, senescence and ageing (Choudhery et al 2012).…”