Diabetes Causes Bone Marrow Autonomic Neuropathy and Impairs Stem Cell Mobilization via Dysregulated p66Shc and Sirt1.

Diabetes compromises the bone marrow (BM) microenvironment and reduces the number of circulating CD34⁺ cells. Diabetic autonomic neuropathy (DAN) may impact the BM, because the sympathetic nervous system is prominently involved in BM stem cell trafficking. We hypothesize that neuropathy of the BM affects stem cell mobilization and vascular recovery after ischemia in patients with diabetes. We report that, in patients, cardiovascular DAN was associated with fewer circulating CD34⁺ cells. Experimental diabetes (streptozotocin-induced and ob/ob mice) or chemical sympathectomy in mice resulted in BM autonomic neuropathy, impaired Lin^-cKit⁺Sca1⁺ (LKS) cell and endothelial progenitor cell (EPC; CD34⁺Flk1⁺) mobilization, and vascular recovery after ischemia. DAN increased the expression of the 66-kDa protein from the src homology and collagen homology domain (p66Shc) and reduced the expression of sirtuin 1 (Sirt1) in mice and humans. p66Shc knockout (KO) in diabetic mice prevented DAN in the BM, and rescued defective LKS cell and EPC mobilization. Hematopoietic Sirt1 KO mimicked the diabetic mobilization defect, whereas hematopoietic Sirt1 overexpression in diabetes rescued defective mobilization and vascular repair. Through p66Shc and Sirt1, diabetes and sympathectomy elevated the expression of various adhesion molecules, including CD62L. CD62L KO partially rescued the defective stem/progenitor cell mobilization. In conclusion, autonomic neuropathy in the BM impairs stem cell mobilization in diabetes with dysregulation of the life-span regulators p66Shc and Sirt1. [ABSTRACT FROM AUTHOR]