Invited commentary

Abstract

Preventing the advancement of or, better yet, reversing peripheral vascular occlusive disease could save many limbs and provide a better quality of life for our patients. The “magic bullet” of an individual agent placed locally to change the milieu sufficiently to improve collateral vascular development or to stimulate angiogenesis has not been successful to date. However, providing cells that can change the local milieu by providing a slurry of beneficial agents is more promising. Mesenchymal stem cells (MSCs) can provide stromal support and paracrine effects of potential benefit. Unfortunately, one group of patients who could benefit most are those with diabetes, and yet their MSCs (dMSCs) have a deficient expansion capacity. This paper tests the hypothesis that dMSCs have a reversible defect in the epidermal growth factor (EGF) receptor pathway that may blunt cell growth and survival. Human platelet lysate (PL), known to be rich in several growth factors including EGF, might reverse this deficiency, as might EGF alone. It tests whether dMSCs can provide angiogenic stimulus of human umbilical vein endothelial cells (ECs) and, therefore, be a viable regenerative treatment. The study demonstrates that MSCs from the bone marrow and adipose tissue of limbs of well-controlled, nonsmoking diabetic patients have similar population doublings and entered senescence after passage 11, confirming deficient expansion capacity. In addition, dMSCs do not express EGF in their secretome while demonstrating robust expression of other angiogens. Supplementing the dMSCs with PL increased phosphorylation of AKT to healthy MSC levels, whereas providing EGF alone increased only phosphorylated extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) to similar levels as that of PL supplementation. MSC invasion increased over time, but there were inconsistent differences of invasion length and chemokine concentration across MSC types and patients. Both cell types were able to stimulate EC proliferation like standard EC growth media and in co-culture demonstrated longer EC sprouts. In contrast to past literature, this study confirms a lack of EGF expression by dMSCs, providing a deficiency that is cell culture modifiable. Adding EGF increased phosphorylated ERK1/2 levels but not pAKT levels, whereas PL increased both, which may be important because both AKT and ERK1/2 signaling pathways promote cell survival, proliferation, and sustained paracrine activity. The lack of EGF may explain the early senescence noted in the study, but exogenous EGF certainly does not fully correct deficient signaling pathways, whereas PL does better but likely not totally in considering prior studies by the same authors. Both types of dMSCs promote EC proliferation and sprouting, which supports the regenerative benefits of these cells if sufficient numbers for local injection are available. This study has limitations regarding sample size, potential lack of generalization (the population was nonsmoking, well-controlled diabetic patients), and potential bias because the control MSCs were from the iliac crest whereas the experimental MSCs were from the tibia. Provided is some detailed explanation as to how these limitations can be interpreted. Overall, this study is another step forward in the basic science wheel of evidence that will eventually lead to a clinical advancement in regenerative medicine aimed at limb salvage. The opinions or views expressed in this commentary are those of the author and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery the Society for Vascular Surgery. Reversible secretome and signaling defects in diabetic mesenchymal stem cells from peripheral arterial disease patientsJournal of Vascular SurgeryVol. 68Issue 6PreviewRegenerative medicine seeks to stall or to reverse the pathologic consequences of chronic diseases. Many people with diabetes have peripheral arterial disease (PAD), which increases their already high risk of major amputation. Cellular therapies are a promising regenerative medicine approach to PAD that can be used to focally inject regenerative cells to endangered tissue beds. Mesenchymal stem cells (MSCs) are known to promote tissue regeneration through stromal support and paracrine stimulation of new blood vessels (angiogenesis). Full-Text PDF Open Archive