Endothelial progenitor cells (EPCs) are essential in vasculogenesis and wound healing, but their circulating and wound level numbers are decreased in diabetes. This study aimed to determine mechanisms responsible for the diabetic defect in circulating and wound EPCs. Since mobilization of BM EPCs occurs via eNOS activation, we hypothesized that eNOS activation is impaired in diabetes, which results in reduced EPC mobilization. Since hyperoxia activates NOS in other tissues, we investigated whether hyperoxia restores EPC mobilization in diabetic mice through BM NOS activation. Additionally, we studied the hypothesis that impaired EPC homing in diabetes is due to decreased wound level stromal cell-derived factor-1α (SDF-1α), a chemokine that mediates EPC recruitment in ischemia. Diabetic mice showed impaired phosphorylation of BM eNOS, decreased circulating EPCs, and diminished SDF-1α expression in cutaneous wounds. Hyperoxia increased BM NO and circulating EPCs, effects inhibited by the NOS inhibitor N-nitro-l-arginine-methyl ester. Administration of SDF-1α into wounds reversed the EPC homing impairment and, with hyperoxia, synergistically enhanced EPC mobilization, homing, and wound healing. Thus, hyperoxia reversed the diabetic defect in EPC mobilization, and SDF-1α reversed the diabetic defect in EPC homing. The targets identified, which we believe to be novel, can significantly advance the field of diabetic wound healing.

Background Percutaneous transluminal angioplasty +/− stent (PTA/S) and surgical bypass are both accepted treatments for claudication due to superficial femoral artery (SFA) occlusive disease. However, long-term results comparing these modalities for primary intervention in patients who have had no prior intervention has not been reported. We report our results with three year follow-up. Methods We reviewed all lower extremity bypass procedures at Beth Israel Deaconess Medical Center from 2001–2009 and all PTA/S performed from 2005 through 2009 for claudication. We excluded all limb salvage procedures and included only those that were undergoing their first intervention for claudication due to SFA disease. We recorded patient demographics, comorbidities, perioperative medications, TASC classification, and runoff. Outcomes included complications, restenosis, symptom recurrence, reinterventions, major amputation, and mortality. Results We identified 113 bypass grafts and 105 PTA/S of femoral-popliteal lesions without prior interventions. Bypasses were above the knee in 62% (45% vein) and below the knee in 38% (100% vein). Mean age was 63 (bypass) vs. 69 (PTA/S) (P<.01). Mean length of stay (LOS) was 3.9 vs. 1.2 days (P<.01). Bypass grafts were used less for TASC A (17% vs. 40%, P<.01), and more for TASC C (36% vs. 11%, P<.01) and TASC D (13% vs. 3%, P<.01) lesions. There were no differences in perioperative (2% vs. 0%, NS) or 3 year mortality (9 vs. 8%, NS). Wound infection was higher with bypass (16% vs. 0%, P<.01). None involved grafts. Bypass showed improved freedom from restenosis (73% vs. 42% - 3 years, HR 0.4, 95% CI 0.23–0.71), symptom recurrence (70% and 36% at 3 years, HR 0.37, 95% CI 0.2–0.56), and freedom from symptoms at last follow-up (83% vs. 49%, (HR 0.18, 95% CI 0.08–0.40). There was no difference in freedom from reintervention (77% vs. 66% at 3 years, NS). Multivariable analysis of all patients showed that restenosis was predicted by PTA/S (HR 2.5, 95% CI 1.4–4.4) and TASC D (HR 3.7, 95% CI 3.5–9) lesions. Recurrence of symptoms was similarly predicted by PTA/S (HR 3.0, 95% CI 1.8–5) and TASC D lesions (HR 3.1, 95% CI 1.4–7). Statin use postoperatively was predictive of patency (HR 0.6 95% CI 0.35–0.97) and freedom from recurrent symptoms (HR 0.6 95% CI 0.36–0.93). Conclusions Surgical bypass for the primary treatment of claudication showed improved freedom from restenosis and symptom relief despite treatment of more extensive disease, but was associated with increased LOS and wound infection. Statins improved freedom from restenosis and symptom recurrence overall.

Adult bone marrow-derived mesenchymal stem cells (MSCs) are able to differentiate into myofibroblasts and be recruited into wound lesions and contribute to wound healing. The cellular and molecular mechanism responsible for MSC trafficking and differentiation, however, are poorly understood. Local resting resident fibroblasts are activated after injury and play a critical role in recruiting MSCs. We investigated the role of platelet derived growth factor-B-activated fibroblasts (PDGF-B-aFBs) in regulating recruitment, migration and differentiation of MSCs from GFP transgenic mice in an in vitro wound healing assay and a novel three-dimensional (3D) model. PDGF-B-aFBs caused significant increases in MSCs migration velocity compared to control as demonstrated by time-lapse photography in an in vitro wound healing assay. Consistently, invasion/ migration of MSCs into 3D collagen gels was enhanced in the presence of PDGF-B-aFbs. In addition, PDGF-B-aFBs induced differentiation of MSCs into myofibroblast. The regulatory effects of PDGF-B-aFBs are likely to be mediated by basic fibroblast growth factor (bFGF) and epithelial neutrophil activating peptide-78 (ENA-78 or CXCL5) as protein array analysis indicated an elevated levels of these two soluble factors in culture supernatant of PDGF-B-aFBs. Blocking antibodies against bFGF and CXCL5 were able to inhibit both trafficking and differentiation of MSCs into 3D collagen gels while supplement of exogenous bFGF and/or CXCL5 promoted invasion/migration of MSCs into 3D collagen gels. Our results reveal that PDGF-B-aFBs play a key role in recruitment/migration and differentiation of MSCs and implicate a bFGF-and CXCL5-dependent mechanism in mediating these effects. KeywordsFibroblasts; Platelet derived growth factor-B (PDGF-B); basic fibroblast growth factor (bFGF); endothelial neutrophil activating peptide-78 (ENA-78) or CXCL5; bone marrow-derived mesenchymal stem cells; wound healing Correspondence to: Omaida C. Velazquez.

Objective Endovascular repair (EVAR) of ruptured abdominal aortic aneurysm (rAAA) has become first-line therapy at our institution and is performed under a standardized protocol. We compare perioperative mortality, midterm survival, and morbidity after EVAR and open surgical repair (OSR). Methods Records were retrospectively reviewed from May 2000 to September 2010 for repair of infrarenal rAAAs. Primary end points included perioperative mortality and midterm survival. Secondary end points included acute limb ischemia, length of stay, ventilator-dependent respiratory failure, myocardial infarction, renal failure, abdominal compartment syndrome, and secondary intervention. Statistical analysis was performed using the t-test,X2 test, the Fisher exact test, and logistic regression calculations. Midterm survival was assessed with Kaplan-Meier analysis and Cox proportional hazard models. Results Seventy-four infrarenal rAAAs were repaired, 19 by EVAR and 55 by OSR. Despite increased age and comorbidity in the EVAR patients, perioperative mortality was 15.7% for EVAR, which was significantly lower than the 49% for OSR (odds ratio, 0.19; 95% CI, 0.05-0.74; P = .008). Midterm survival also favored EVAR (hazard ratio, 0.40; 95% CI, 0.21-0.77; P = .028, adjusted for age and sex). Mean follow-up was 20 months, and 1-year survival was 60% for EVAR vs 45% for OSR. Mean length of stay for patients surviving >1 day was 10 days for EVAR and 21 days for OSR (P = .004). Ventilator-dependent respiratory failure was 5% in the EVAR group vs 42% for OSR (odds ratio, 0.08; 95% CI, 0.01-0.62; P = .001). Conclusions EVAR of rAAA has a superior perioperative survival advantage and decreased morbidity vs OSR. Although not statistically significant, overall survival favors EVAR. We recommend that EVAR be considered as the first-line treatment of rAAAs and practiced as the standard of care.

Objective Matrix metalloproteinase-2 (MMP-2) degrades type IV collagen and enables endothelial cell (EC) migration during angiogenesis and wound healing. PEX2 is a byproduct of activated MMP-2 autocatalysis and competitively inhibits newly activated MMP-2 from EC surface binding and migration. We hypothesize that PEX2 is elevated during limb ischemia, contributing to poor wound healing by interfering with angiogenesis. We aim to identify elevated PEX2 in ischemic murine hindlimb muscle and demonstrate poor healing with decreased capillary density. Methods Western blot was used to identify PEX2 in hindlimbs of FVB/NJ mice with surgically induced ischemia. The PEX2 effect on healing was evaluated by calculating area of exposed muscle after wounding the dorsum of mice and performing daily injections with recombinant PEX2 (hrPEX2). Additionally, wounds were injected with lentivirus expressing PEX2 (PEX2-LV), harvested on post operative day 7 (POD 7), fixed and sectioned for staining with hematoxylin and eosin (H&E). Epithelial gap was assessed with light microscopy. Capillary density was evaluated after wounding Tie2-GFP+ transgenic FVB mice (ECs labeled green) and viral transduction with PEX2-LV. Wounds were harvested on POD 7, frozen in liquid nitrogen, sectioned and stained with Hoechst. Vessel density was assessed via fluorescence microscopy as average number of capillaries per ten high powered fields (HPF). Paired Student’s t-test was used to assess differences between the groups. Results PEX2 was elevated 5.5-fold (±2.0, P= .005) on POD 2 and 2.9-fold (±0.69, P= .004) on POD 4 in gastrocnemius muscles of ischemic hindlimbs. The wound surface area, or lack of granulation tissue and exposed muscle, decreased daily in all mice, but was greater in the hrPEX mice by 12% to 16% (P< .004). Wounds in the control group were completely covered with granulation tissue by POD 3, whereas wounds injected with hrPEX2 were not completely covered by POD 7, but continued to have exposed muscle. Microscopic examination of wounds after PEX2-LV viral transduction, demonstrated an average epithelial gap of 1.6±0.3μm versus 0.64±0.3 μm in control wounds (P< .04). Wounds from Tie-2-GFP mice had an average number of 3.8±1.1 capillaries versus 6.9±1.2 in control wounds (P< .007). Conclusion Our study is the first report linking elevated PEX2 to ischemia and poor wound healing. We demonstrate comparative PEX2 elevation in ischemic murine hindlimbs. Wounds subjected to hrPEX2 or viral transduction with PEX2-LV produce less granulation tissue and retarded healing. Microscopic evaluation of the wounds exhibit fewer capillaries, supporting the hypothesis that PEX2 decreases angiogenesis.