OBJECTIVEProgenitor cells (PCs) contribute to postnatal neovascularization and tissue repair. Here, we explore the mechanism contributing to decreased diabetic circulating PC number and propose a novel treatment to restore circulating PC number, peripheral neovascularization, and tissue healing.RESEARCH DESIGN AND METHODSCutaneous wounds were created on wild-type (C57BL/J6) and diabetic (Leprdb/db) mice. Blood and bone marrow PCs were collected at multiple time points.RESULTSSignificantly delayed wound closure in diabetic animals was associated with diminished circulating PC number (1.9-fold increase vs. 7.6-fold increase in lin−/sca-1+/ckit+ in wild-type mice; P < 0.01), despite adequate numbers of PCs in the bone marrow at baseline (14.4 ± 3.2% lin−/ckit+/sca1+ vs. 13.5 ± 2.8% in wild-type). Normal bone marrow PC mobilization in response to peripheral wounding occurred after a necessary switch in bone marrow stromal cell-derived factor-1α (SDF-1α) expression (40% reduction, P < 0.01). In contrast, a failed switch mechanism in diabetic bone marrow SDF-1α expression (2.8% reduction) resulted in impaired PC mobilization. Restoring the bone marrow SDF-1α switch (54% reduction, P < 0.01) with plerixafor (Mozobil, formerly known as AMD3100) increased circulating diabetic PC numbers (6.8 ± 2.0-fold increase in lin−/ckit+, P < 0.05) and significantly improved diabetic wound closure compared with sham-treated controls (32.9 ± 5.0% vs. 11.9 ± 3% at day 7, P > 0.05; 73.0 ± 6.4% vs. 36.5 ± 7% at day 14, P < 0.05; and 88.0 ± 5.7% vs. 66.7 ± 5% at day 21, P > 0.05, respectively).CONCLUSIONSSuccessful ischemia-induced bone marrow PC mobilization is mediated by a switch in bone marrow SDF-1α levels. In diabetes, this switch fails to occur. Plerixafor represents a potential therapeutic agent for improving ischemia-mediated pathology associated with diabetes by reducing bone marrow SDF-1α, restoring normal PC mobilization and tissue healing.

(2016) Intestinal bacteria are necessary for doxorubicin-induced intestinal damage but not for doxorubicin-induced apoptosis, Gut Microbes, 7:5, 414-423, DOI: 10.1080/19490976.2016 To link to this article: https://doi.org/10. 1080/19490976.2016 ABSTRACT Doxorubicin (DOXO) induces significant, but transient, increases in apoptosis in the stem cell zone of the jejunum, followed by mucosal damage involving a decrease in crypt proliferation, crypt number, and villus height. The gastrointestinal tract is home to a vast population of commensal bacteria and numerous studies have demonstrated a symbiotic relationship between intestinal bacteria and intestinal epithelial cells (IEC) in maintaining homeostatic functions of the intestine. However, whether enteric bacteria play a role in DOXO-induced damage is not well understood. We hypothesized that enteric bacteria are necessary for induction of apoptosis and damage associated with DOXO treatment. Conventionally raised (CONV) and germ free (GF) mice were given a single injection of DOXO, and intestinal tissue was collected at 6, 72, and 120 h after treatment and from no treatment (0 h) controls. Histology and morphometric analyses quantified apoptosis, mitosis, crypt depth, villus height, and crypt density. Immunostaining for muc2 and lysozyme evaluated Paneth cells, goblet cells or dual stained intermediate cells. DOXO administration induced significant increases in apoptosis in jejunal epithelium regardless of the presence of enteric bacteria; however, the resulting injury, as demonstrated by statistically significant changes in crypt depth, crypt number, and proliferative cell number, was dependent upon the presence of enteric bacteria. Furthermore, we observed expansion of Paneth and goblet cells and presence of intermediate cells only in CONV and not GF mice. These findings provide evidence that manipulation and/or depletion of the enteric microbiota may have clinical significance in limiting chemotherapy-induced mucositis.

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Flap ischemia induces phenotypic changes in bone marrow-derived endothelial progenitor cells that subsequently traffic through the circulation. The vasculogenic potential of endothelial progenitor cells at various stages of differentiation is impaired in diabetes and thus may account for impaired ischemia-induced vasculogenesis observed clinically.