Speaker
Description
"INTRODUCTION: Mesenchymal stromal cells (MSCs) are potential candidates in tissue engineering applications. Nevertheless, MSC-based therapies have fallen short of the initial promise and hype due to the low MSC retention rate caused by the disruption of nutrient and oxygen supplies. Our previous studies established that the lack of glucose (but not oxygen) is fatal to human MSCs (hMSCs) because it acts as a pro-survival molecule for hMSCs upon transplantation. As a first step towards the engineering of a glucose releasing hydrogel, this study aims to provide insights into the effects of glucose on hMSCs paracrine function pertinent to angiogenesis in vitro and in vivo.
METHODOLOGY: In vitro experiment: Release of bioactive factors, angiogenic potential, and chemo-attractive potential of conditioned media (CM) from hMSCs towards human umbilical vein endothelial cells (HUVECs) were performed using Multiplex Luminex® Assays, Matrigel-Based Tube Formation Assay, and Incucyte® Live Cell Analysis System, respectively. The CM was obtained by exposure of hMSC to near-anoxia in the presence of glucose at 0, 1, or 5 g/L for 3 days. In vivo experiment: hMSC pro-angiogenic potential was investigated using hMSC-containing hydrogels loaded with either 0, 1, 5, 10, or 20 g/L glucose and hMSC-free hydrogels loaded with 20 g/L glucose, which were implanted ectopically in nude mice. The formation of new blood vessels was quantified using a micro-CT scanner after Microfil® injection at 21 days.
RESULTS: Glucose improves angioinduction of MSCs in near anoxia: Supernatant CM collected from hMSCs cultured with either 1 or 5 g/L glucose in near-anoxia for 3 days increased HUVECs migration and formation of vascular-like structure compared to that in the CM collected from hMSCs cultured without glucose. These data were corroborated by the increased amounts of pro-angiogenic factors (Angiogenin, VEGF-A, VEGF-C, Angiopoietin-1, Endostatin, and CCL2) in the CM collected from hMSCs cultured with glucose. Glucose improves the survival of MSCs and new blood vessels formation post-implantation: Upon ectopic implantation into nude mice, the volume of newly formed blood vessels within hMSCs-containing hydrogels loaded either 5, 10, and 20 g/L glucose exhibited a 2.4, 2.8, and 2.4 fold increase compared to hMSCs-containing hydrogels without glucose at days 21 post-implantation, respectively.
CONCLUSION: These data demonstrate that critical impact of glucose on MSC-mediated angiogenesis both in vitro under near-anoxia and in vivo using an ectopic mouse model. Further investigations are ongoing to determine whether endoplasmic reticulum stress is involved in the positive effects of glucose in MSC-mediated angiogenesis. All in all, the in vivo delivery of hMSCs in the presence of glucose strategy may be broadly helpful to improve not only the survival but also the angioinductive potential of hMSC-based therapies."
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