Bone Marrow Endothelial Progenitor Cells Research Articles

Bone Marrow Endothelial Progenitor Cells Are the Cellular Mediators of Pulmonary Hypertension in the Murine Monocrotaline Injury Model.

The role of bone marrow (BM) cells in modulating pulmonary hypertensive responses is not well understood. Determine if BM‐derived endothelial progenitor cells (EPCs) induce pulmonary hypertension (PH) and if this is attenuated by mesenchymal stem cell (MSC)‐derived extracellular vesicles (EVs). Three BM populations were studied: (a) BM from vehicle and monocrotaline (MCT)‐treated mice (PH induction), (b) BM from vehicle‐, MCT‐treated mice that received MSC‐EV infusion after vehicle, MCT treatment (PH reversal, in vivo), (c) BM from vehicle‐, MCT‐treated mice cultured with MSC‐EVs (PH reversal, in vitro). BM was separated into EPCs (sca‐1+/c‐kit+/VEGFR2+) and non‐EPCs (sca‐1‐/c‐kit‐/VEGFR2‐) and transplanted into healthy mice. Right ventricular (RV) hypertrophy was assessed by RV‐to‐left ventricle+septum (RV/LV+S) ratio and pulmonary vascular remodeling by blood vessel wall thickness‐to‐diameter (WT/D) ratio. EPCs but not non‐EPCs from mice with MCT‐induced PH (MCT‐PH) increased RV/LV+S, WT/D ratios in healthy mice (PH induction). EPCs from MCT‐PH mice treated with MSC‐EVs did not increase RV/LV+S, WT/D ratios in healthy mice (PH reversal, in vivo). Similarly, EPCs from MCT‐PH mice treated with MSC‐EVs pre‐transplantation did not increase RV/LV+S, WT/D ratios in healthy mice (PH reversal, in vitro). MSC‐EV infusion reversed increases in BM‐EPCs and increased lung tissue expression of EPC genes and their receptors/ligands in MCT‐PH mice. These findings suggest that the pulmonary hypertensive effects of BM are mediated by EPCs and those MSC‐EVs attenuate these effects. These findings provide new insights into the pathogenesis of PH and offer a potential target for development of novel PH therapies. Stem Cells Translational Medicine 2017;6:1595–1606

Layer-by-layer bioassembly of cellularized polylactic acid porous membranes for bone tissue engineering.

The conventional tissue engineering is based on seeding of macroporous scaffold on its surface ("top-down" approach). The main limitation is poor cell viability in the middle of the scaffold due to poor diffusion of oxygen and nutrients and insufficient vascularization. Layer-by-Layer (LBL) bioassembly is based on "bottom-up" approach, which considers assembly of small cellularized blocks. The aim of this work was to evaluate proliferation and differentiation of human bone marrow stromal cells (HBMSCs) and endothelial progenitor cells (EPCs) in two and three dimensions (2D, 3D) using a LBL assembly of polylactic acid (PLA) scaffolds fabricated by 3D printing. 2D experiments have shown maintain of cell viability on PLA, especially when a co-cuture system was used, as well as adequate morphology of seeded cells. Early osteoblastic and endothelial differentiations were observed and cell proliferation was increased after 7 days of culture. In 3D, cell migration was observed between layers of LBL constructs, as well as an osteoblastic differentiation. These results indicate that LBL assembly of PLA layers could be suitable for BTE, in order to promote homogenous cell distribution inside the scaffold and gene expression specific to the cells implanted in the case of co-culture system.

Transplantation of Amniotic Scaffold-Seeded Mesenchymal Stem Cells and/or Endothelial Progenitor Cells From Bone Marrow to Efficiently Repair 3-cm Circumferential Urethral Defect in Model Dogs.

The treatment options for patients with a urethral defect are limited by the availability of autologous tissues. We hypothesized that transplantation of decellularized human amniotic scaffolds (dHAS) seeded with allogeneic bone marrow mesenchymal cells (BMSCs) and/or endothelial progenitor cells (EPCs) may serve as a promising repair strategy for long segment of circumferential urethral defect. To verify the hypothesis, with urinary catheterization, a 3-cm segment of whole urethra in 25 male mongrel dogs was excised and replaced by dHAS seeded with allogeneic BMSCs and/or EPCs. Postoperative observation and ascending urethrogram found that dHAS+BMSCs+EPCs and dHAS+EPCs groups demonstrated unhindered urination and capacious urethral caliber, which were similar to the normal group, while urethrostenosis was revealed in dHAS+BMSCs, dHAS, and sham-operated groups, with the shortest narrow section in dHAS+BMSCs group and the longest in sham-operated group. Urethral anatomy check and histological analyses showed that new urethral mucosa composed of stratified columnar epithelium completely covered on the inner surface of the graft site in dHAS+BMSCs+EPCs and dHAS+EPCs groups, but the middle epithelium was thin in dHAS+EPCs group, while incompletely covered in dHAS+BMSCs, dHAS, and sham-operated groups, and there were monolayer epithelial cells at the urethrostenosis in dHAS+BMSCs and dHAS groups. In addition, abundant new vessel and blood sinus showed at submucosa in dHAS+BMSCs+EPCs and dHAS+EPCs groups, instead of the scar tissue of collagen deposition and structural distortion at the urethrostenosis in dHAS+BMSCs, dHAS, and sham-operated groups. This study demonstrates that dHAS seeded with BMSCs+EPCs or EPCs can successfully repair a 3-cm circumferential urethral defect in model dogs, but the former works best. This technology may provide some references for human clinical trials on long segment of circumferential urethral defect repair.

Intravenously Transplanted Human Bone Marrow Endothelial Progenitor Cells Engraft Within Brain Capillaries, Preserve Mitochondrial Morphology, and Display Pinocytotic Activity Toward Blood-Brain Barrier Repair in Ischemic Stroke Rats.

Stroke is a life-threatening disease with limited therapeutic options. Cell therapy has emerged as an experimental stroke treatment. Blood-brain barrier (BBB) impairment is a key pathological manifestation of ischemic stroke, and barrier repair is an innovative target for neurorestoration in stroke. Here, we evaluated via electron microscopy the ability of transplanted human bone marrow endothelial progenitor cells (hBMEPCs) to repair the BBB in adult Sprague-Dawley rats subjected to transient middle cerebral artery occlusion (tMCAO). β-galactosidase prelabeled hBMEPCs were intravenously transplanted 48 hours post-tMCAO. Ultrastructural analysis of microvessels in nontransplant stroke rats revealed typical BBB pathology. At 5 days post-transplantation with hBMEPCs, stroke rats displayed widespread vascular repair in bilateral striatum and motor cortex, characterized by robust cell engraftment within capillaries. hBMEPC transplanted stroke rats exhibited near normal morphology of endothelial cells (ECs), pericytes, and astrocytes, without detectable perivascular edema. Near normal morphology of mitochondria was also detected in ECs and perivascular astrocytes from transplanted stroke rats. Equally notable, we observed numerous pinocytic vesicles within engrafted cells. Robust engraftment and intricate functionality of transplanted hBMEPCs likely abrogated stroke-altered vasculature. Preserving mitochondria and augmenting pinocytosis in cell-based therapeutics represent a new neurorestorative mechanism in BBB repair for stroke. Stem Cells 2017;35:1246-1258.

Mesenchymal stem cells promote endothelial progenitor cell proliferation by secreting insulin‑like growth factor‑1.

Bone marrow mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) interact with each other. EPCs are able to promote the self‑renewal of MSCs as niche cells in murine bone marrow, and MSCs are able to promote EPC proliferation invitro in a co‑culture system. It has previously been reported that MSCs can secrete insulin‑like growth factor‑1 (IGF‑1), which serves critical functions in EPC proliferation. However, the mechanism underlying the IGF‑1‑mediated proliferation of EPCs remains unclear. The aim of the present study was to reveal the molecular mechanisms regulating this process. The effects of IGF‑1, which is secreted by MSCs, on EPC proliferation via the PI3K/Akt signaling pathway were examined by MTT assay, reverse transcription‑quantitative polymerase chain reaction and western blot analysis. The present study treated EPCs with various concentrations of IGF‑1. The results demonstrated that IGF‑1 significantly induced the proliferation of cultured EPCs. However, this effect was offset by treatment with the phosphatidylinositol 3‑kinase (PI3K) inhibitor LY294002. These results indicated that the pro‑proliferative effects of IGF‑1 are mediated in response to the PI3K/protein kinase B signaling pathway.

Endothelial Progenitor Cells: Procedure for Cell Isolation and Applications.

Bone marrow endothelial progenitor cells (EPCs) have shown a great promise to promote ischemic tissue neovascularization and to attenuate ischemic injury in a variety of animal models, which led to EPC-based clinical trials that yielded modest but promising results. Some of the variables in the use of EPCs relate to their differential isolation and characterization protocols since the EPC literature does not identify a unique marker for these vascular progenitors. In this chapter, we present step-by-step protocols for the isolation of EPCs, their characterization and culture conditions, and their potential use in basic and clinical research.

Atorvastatin enhances endothelial cell function in posttransplant poor graft function

AbstractPoor graft function (PGF) is a serious complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Murine studies suggest that endothelial progenitor cells (EPCs) are preferential supporting cells for hematopoietic stem cells in the bone marrow (BM) microenvironment. Our previous work found that a reduced number of BM EPCs was an independent risk factor for the occurrence of PGF after allo-HSCT. However, little is known about the functional role of BM EPCs and how to improve impaired BM EPCs in PGF. In the current study, we evaluated the function of BM EPCs in subjects with PGF postallotransplant. Moreover, we investigated whether atorvastatin could enhance the number and function of BM EPCs derived from subjects with PGF in vitro. Dysfunctional BM EPCs, which were characterized by impaired proliferation, migration, angiogenesis, and higher levels of reactive oxygen species and apoptosis, were revealed in subjects with PGF. Activation of p38 and its downstream transcription factor cyclic adenosine monophosphate–responsive element-binding protein were detected in BM EPCs from subjects with PGF. Furthermore, the number and function of BM EPCs derived from subjects with PGF were enhanced by atorvastatin treatment in vitro through downregulation of the p38 MAPK pathway. In summary, dysfunctional BM EPCs were observed in subjects with PGF. Atorvastatin treatment in vitro quantitatively and functionally improved BM EPCs derived from subjects with PGF through downregulation of the p38 MAPK pathway. These data indicate that atorvastatin represents a promising therapeutic approach for repairing impaired BM EPCs in subjects with PGF postallotransplant.

Dysfunction of Bone Marrow Endothelial Progenitor Cells from Subjects with Poor Graft Function Following Allogeneic Hematopoietic Stem Cell Transplantation Can be Improved By Atorvastatin

BackgroundPoor graft function (PGF) is a serious complication post allo-HSCT. The definition is a hypo- or aplastic bone marrow with 2 or 3 of the following: (1) neutrophils ≤0.5×10E+9/L; (2) platelets ≤20×10E+9/L; and/or (3) hemoglobin concentration ≤70 g/L for at least 3 consecutive days after day +28 post-HSCT. The mechanisms of PGF remain poorly understood. Murine studies suggest that endothelial progenitor cells (EPCs) are preferential supporting cells for hematopoietic stem cells (HSCs) in the bone marrow (BM) microenvironment. In addition, our previous prospective, nested case-control study found that a reduced number of BM EPCs was an independent risk factor for the occurrence of PGF after allo-HSCT. However, little is known about the functional role of BM EPCs and how to improve impaired BM EPCs in PGF.Atorvastatin is widely used in the treatment of dyslipidemia and associated vascular abnormalities. Furthermore, atorvastatin has been reported to improve the mobilization and function of circulating EPCs in a number of diseases, such as heart disease, diabetes and others. Nevertheless, no previous studies have focused on the roles of atorvastatin on bone marrow-derived EPCs in subjects with poor graft function following allo-HSCT.AimsTo evaluate the function of BM EPCs in subjects with PGF. Moreover, to investigate the effect of atorvastatin on the number and function of cultivated BM EPCs derived from subjects with PGF and its underling molecular mechanisms.MethodsThree cohorts were included: subjects with PGF (N=23), subjects with good graft function (N=23), defined as persistent successful engraftment after allotransplant, and transplant donors as normal controls (N=23). Atorvastatin (0.5nM,50nM,500nM) was administrated to the 5 day cultivated BM EPCs from subjects with PGF until tested on day 7. The number and functions of CD34(+)/CD133(+)/KDR(+)EPCs were evaluated by flow cytometry, cell counting, DiI-Ac-LDL and FITC-lectin-UEA-1 double staining, migration, tube formation test and apoptosis. Reactive Oxygen Species (ROS) level was evaluated by flow cytometry. Cell proliferation was determined by cell counting kit-8 assay. Protein expression for ERK,JNK, p38, Akt was measured by flow cytometry and western blots. EPCs-CD34+ co-culture system and Colony-forming unit (CFU) assays were used to evaluate the supporting effect that atorvastatin exposure on hematopoietic progenitors in vitro.ResultsHuman BM EPCs was characterized by the spindle shape and expression of CD34, CD309 and CD133 at day 7 of cultivation. Dysfunctional BM EPCs, which were characterized by impaired proliferation, migration, angiogenesis, and higher levels of reactive oxygen species and apoptosis, were revealed in subjects with PGF. Activation of p38 and its downstream transcription factor cAMP-responsive element-binding protein (CREB) were detected in BM EPCs from subjects with PGF. Furthermore, the number and function of BM EPCs derived from subjects with PGF were enhanced by atorvastatin treatment in vitro through down-regulation of the p38 mitogen-activated protein kinase (MAPK) pathway. The colony-forming unit plating efficiency in CD34+ BM cells was also improved by atorvastatin when co-cultured with BM EPCs from subjects with PGF. Atorvastatin demonstrated similar improvement effects on the number and function of bone marrow EPCs as ROS inhibitor and p38 inhibitor from subjects with PGF.ConclusionIn summary, dysfunctional BM EPCs were observed in subjects with PGF. Atorvastatin treatment in vitro quantitatively and functionally improved BM EPCs derived from subjects with PGF through down-regulation of the p38 MAPK pathway. These data indicate that atorvastatin represents a promising therapeutic approach for repairing impaired BM EPCs in subjects with PGF post-allotransplant. DisclosuresNo relevant conflicts of interest to declare.

Effect of Naoxintong capsule on endothelial progenitor cell mobilization and homing following bone marrow transplantation in a mouse hind limb ischemia model

Endothelial progenitor cells (EPCs) are precursor cells of endothelial cells. Signal molecules produced by ischemia and hypoxia can promote mobilization of bone marrow EPCs to peripheral circulation and formation of novel blood vessels in tissues that are damaged during heart attack. Naoxintong capsule (NXT) has the functions of promoting blood circulation, removing blood stasis, promoting the circulation of qi and relieving pain. The various components in NXT have protective effects on blood vessels and can effectively improve the symptoms of ischemia. However, its effect on EPCs is not clear. To study the intervention effect of NXT on mobilization and homing of peripheral blood EPCs, green fluorescent protein (GFP) transgenic mice were used for bone marrow transplantation (BMT) and then unilateral hind limb ischemia model (UHLI) were constructed. For BMT, wild-type ICR mice were irradiated by CS137 and then injected with 4×106 bone marrow cells isolated from GFP mice. The bone marrow reconstitution of recipients was assessed by quantification of GFP bone marrow-derived cells (BMDC) from transplanted mice 4 weeks after BMT. The UHLI model was duplicated by ligating femoral artery and divided into three groups: the model group, the NXT group (model+NXT) and the positive control group (model+simvastatin). Flow cytometry was used to detect the proportion of GFP positive cells and the peripheral blood EPCs levels at 1, 3, 7, 14 days before and after surgery. Ischemic tissue of gastrocnemius muscle was excised at 3 and 7 days after operation for immunofluorescence staining to detect the number of GFP+ cells. The bone marrow chimerism was achieved at day 28 after BMT. There was no significant difference in the percentage of GFP positive cells between BMT mice and GFP transgenic mice. NXT and simvastatin could significantly increase the number of peripheral blood EPCs 1,3 days after surgery. Three and seven days after operation, the number of homing EPCs was significantly higher in NXT group and positive control group than that in model group (P<0.001). In conclusion, NXT can obviously promote the mobilization and homing of EPCs.

Brief Report: Vitamin D Deficiency Is Associated With Endothelial Dysfunction and Increases Type I Interferon Gene Expression in a Murine Model of Systemic Lupus Erythematosus.

Patients with systemic lupus erythematosus (SLE) have an increased risk of cardiovascular disease (CVD) and impaired endothelial repair. Although vitamin D deficiency is associated with increased CVD risk in the general population, a causal relationship has not been demonstrated. We aimed to determine whether vitamin D deficiency directly modulates endothelial dysfunction and immune responses in a murine model of SLE. Vitamin D deficiency was induced in lupus-prone MRL/lpr mice by dietary restriction for 6 weeks. Endothelium-dependent vasorelaxation was quantified using aortic ring myography, and endothelial repair mechanisms were assessed by evaluating the phenotype and function of bone marrow endothelial progenitor cells (EPCs) and with the use of an in vivo Matrigel plug model. Lupus disease activity was determined by evaluating expression of interferon-stimulated genes (ISGs) in splenic tissue, positivity for serum autoantibodies, and renal histology. To validate the findings, expression of ISGs was also measured in whole blood from vitamin D-deficient and vitamin D-sufficient patients with SLE. Vitamin D deficiency resulted in impaired endothelium-dependent vasorelaxation and decreases in neoangiogenesis without a change in the total number of EPCs. There were no differences in anti-double-stranded DNA titers, proteinuria, or glomerulonephritis (activity or chronicity) between vitamin D-deficient or sufficient mice. Vitamin D deficiency was associated with a trend toward increased ISG expression both in mice and in patients with SLE. These findings indicate that vitamin D deficiency is associated with hampered vascular repair and reduced endothelial function, and may modulate type I interferon responses.

Effects of maternal high-fat diet and statin treatment on bone marrow endothelial progenitor cells and cardiovascular risk factors in female mice offspring fed a similar diet

ObjectivesThe aim of this study was to prove that one possible statin-related protective mechanism in dams and offspring fed a high-fat diet (HFD) is the reduction in cardiovascular risk and impairment of the vasculogenic element of endothelial regeneration. MethodsTo explore this, virgin C57 BL/6 mice (n = 8/group) were fed an HFD (fat: 45% kcal) or standard chow (C; fat: 21% kcal) from weaning and throughout their pregnancy and lactation. Half of the HFD group also was given the 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor pravastatin (S) through their drinking water (5 mg/kg body weight per day) to create HF+S dam group (n = 8/group). Offspring from each group were fed HFD or C diet from weaning to adulthood, generating respective dam/offspring dietary groups (C/C, HF/HF, HF+S/HF; n = 8/group). Body weight, blood pressure, and serum lipid profile were measured in female offspring at age 24 wk, and bone marrow endothelial progenitor cells (EPCs) were cultured. ResultsThe results indicated that in the female offspring, the statin-fed (HF+S/HF) cohort had lower total and low-density lipoprotein cholesterol concentrations, were less obese and hypertensive, and had reduced C-reactive proteins (CRPs) compared with the HF/HF phenotype. The results also showed an increased bone marrow EPCs expressing colony numbers (P < 0.001) compared with the HF/HF phenotype. ConclusionsResults from the present study demonstrated that statin administration in early life to dams fed on a HFD had a significant effect on their female offspring in terms of reduction in cardiovascular risk factors. Additionally, statin administration to female offspring on an HFD during early life was associated with reduction in circulating CRPs and an increased bone marrow EPC numbers and colony-forming characteristics.

Invited commentary

Dr Edwards and colleagues have detailed the in vivo angiogenic potential of an engineered stromal cell-derived factor-1α (SDF) in a rat arterial ligation model. SDF is a powerful chemoattractant of endothelial progenitor cells (EPCs), which represent a cornerstone of the response to ischemia and angiogenesis. Several studies have highlighted the therapeutic role of SDF to increase migration of EPCs and activation of EPCs, to improve healing of diabetic wounds, and to improve angiogenesis and ventricular physiology in cardiac models. A major hurdle to translation of SDF clinically has been the susceptibility to protease degradation and a complex tertiary structure that limits cost-effective production. Gene delivery approaches to overcome these issues add orders of magnitude to the complexity of potential SDF therapies in terms of vector toxicity and regulation of gene expression. The distinctive aspect of this study by Edwards et al is the use of an engineered SDF analog (ESA) peptide that mimics the physiologic properties of recombinant SDF but at a fraction of the size. The authors found that administration of ESA resulted in increased vascular endothelial growth factor expression, capillary density, and limb perfusion over a clinically relevant interval of 14 days. A significant limitation of this study was the administration of the cytokine granulocyte-macrophage colony-stimulating factor (GMCSF) to upregulate bone marrow EPCs in all study groups. Although GMCSF alone has not been shown to improve perfusion without a chemotactic agent such as SDF, the prospective administration of GMCSF clinically represents a significant additional therapeutic for eventual clinical translation. If future studies can demonstrate that ESA mediates angiogenesis independent of GMCSF, this would significantly improve the appeal of engineered SDF. Also, as noted by the authors, they used a model of acute rather than the intended clinical application of chronic ischemia. Potentially, mechanisms of EPC recruitment and the effect of SDF therapies might differ between these two scenarios. Although angiogenic therapies are unlikely to replace current macrovascular open and endovascular surgical approaches, they will be especially useful in scenarios where distal outflow has been compromised by conditions such as diabetes or chronic distal embolism, for instance. Broadly, these therapies should improve distal tissue perfusion and offer additional applications in coronary ischemia. The findings of this study are compelling and represent a meaningful step toward the frontier of angiogenic therapy in peripheral vascular disease. Biochemically engineered stromal cell-derived factor 1-alpha analog increases perfusion in the ischemic hind limbJournal of Vascular SurgeryVol. 64Issue 4PreviewDespite promising therapeutic innovation over the last decade, peripheral arterial disease remains a prevalent morbidity, as many patients are still challenged with peripheral ischemia. We hypothesized that delivery of engineered stromal cell-derived factor 1-alpha (ESA) in an ischemic hind limb will yield significant improvement in perfusion. Full-Text PDF Open Archive

Electroacupuncture modulates stromal cell-derived factor-1α expression and mobilization of bone marrow endothelial progenitor cells in focal cerebral ischemia/reperfusion model rats

Stromal cell-derived factor-1α(SDF-1α) plays a crucial role in regulating the mobilization, migration and homing of endothelial progenitor cells(EPCs). Electroacupuncture(EA), a modern version of Traditional Chinese Medicine, can improve neurological recovery and angiogenesis in cerebral ischemic area. This study aimed to investigate the effects of electroacupuncture(EA) on the mobilization and migration of bone marrow EPCs and neurological functional recovery in rats model after focal cerebral ischemia/reperfusion and the potentially involved mechanisms. Sprague-Dawley rats received filament occlusion of the right middle cerebral artery for 2h followed by reperfusion for 12h, 1d, 2d, 3d, 7d respectively. Rats were randomly divided into sham group, model group and EA group. After 2h of the reperfusion, EA was given at the “Baihui” (GV 20)/Siguan (“Hegu” (LI 4)/“Taichong” (LR 3)) acupoints in the EA group. Modified neurological severity score (mNSS) was used to assess the neurological functional recovery. EPCs number and SDF-1α level in bone marrow(BM) and peripheral blood(PB) were detected by using fluorescence-activated cell sorting (FACS) analysis and quantitative real time polymerase chain reaction (qRT-PCR) respectively. An mNSS test showed that EA treatment significantly improved the neurological functional outcome. EPCs number in PB and BM were obviously increased in the EA group. After cerebral ischemia, the SDF-1α level was decreased in BM while it was increased in PB, which implied a gradient of SDF-1α among BM and PB after ischemia. It suggested that the forming of SDF-1α concentration gradient can induce the mobilization and homing of EPCs. Eletroacupuncture as a treatment can accelerate and increase the forming of SDF-1α concentration gradient to further induce the mobilization of EPCs and angiogenesis in ischemic brain and improve the neurological function recovery.

Diabetic wound healing in a MMP9‐/‐ mouse model

Reduced mobilization of endothelial progenitor cells (EPCs) from the bone marrow (BM) and impaired EPC recruitment into the wound represent a fundamental deficiency in the chronic ulcers. However, mechanistic understanding of the role of BM-derived EPCs in cutaneous wound neovascularization and healing remains incomplete, which impedes development of EPC-based wound healing therapies. The objective of this study was to determine the role of EPCs in wound neovascularization and healing both under normal conditions and using single deficiency (EPC) or double-deficiency (EPC + diabetes) models of wound healing. MMP9 knockout (MMP9 KO) mouse model was utilized, where impaired EPC mobilization can be rescued by stem cell factor (SCF). The hypotheses were: (1) MMP9 KO mice exhibit impaired wound neovascularization and healing, which are further exacerbated with diabetes; (2) these impairments can be rescued by SCF administration. Full-thickness excisional wounds with silicone splints to minimize contraction were created on MMP9 KO mice with/without streptozotocin-induced diabetes in the presence or absence of tail-vein injected SCF. Wound morphology, vascularization, inflammation, and EPC mobilization and recruitment were quantified at day 7 postwounding. Results demonstrate no difference in wound closure and granulation tissue area between any groups. MMP9 deficiency significantly impairs wound neovascularization, increases inflammation, decreases collagen deposition, and decreases peripheral blood EPC (pb-EPC) counts when compared with wild-type (WT). Diabetes further increases inflammation, but does not cause further impairment in vascularization, as compared with MMP9 KO group. SCF improves neovascularization and increases EPCs to WT levels (both nondiabetic and diabetic MMP9 KO groups), while exacerbating inflammation in all groups. SCF rescues EPC-deficiency and impaired wound neovascularization in both diabetic and nondiabetic MMP9 KO mice. Overall, the results demonstrate that BM-derived EPCs play a significant role during wound neovascularization and that the SCF-based therapy with controlled inflammation could be a viable approach to enhance healing in chronic diabetic wounds.

Metformin improves the angiogenic functions of endothelial progenitor cells via activating AMPK/eNOS pathway in diabetic mice.

BackgroundEndothelial dysfunction has been suggested as a possible causal link between hyperglycemia and microvascular complications in diabetes mellitus. The effect of metformin on endothelial progenitor cells (EPCs) is still unclear. This study was designed to test the hypothesis that metformin could accelerate wound healing by improving the impaired EPC functions in streptozotocin-induced diabetic mice.MethodsStreptozotocin (STZ, 60 mg/kg/d × 5 d, i.p.) was injected to induce type 1 diabetes in male C57BL/6 mice. Mice were treated with metformin (250 mg/kg/d, i.g.) for consecutive 14 days. Wound closure was evaluated by wound area and number of CD31 stained capillaries. Functions of bone marrow-endothelial progenitor cells (BM-EPCs) were assessed by tube formation and migration assays, and expression of AMP-activated protein kinase (AMPK) and endothelial nitric oxide synthase (eNOS) was determined by western blot analysis.ResultsMetformin accelerated wound closure and stimulated angiogenesis in diabetic mice. The number of circulating EPCs was increased significantly in metformin treated diabetic mice. Abilities of tube formation and migration of BM-EPCs were impaired in diabetic mice, which were improved by metformin. Expression of both phosphorylated-AMPK and phosphorylated-eNOS was significantly increased, and nitric oxide (NO) production was enhanced by metformin in BM-EPCs of diabetic mice. In vitro, metformin improved impaired BM-EPC functions, and increased phosphorylated-eNOS expression and NO production in cultured BM-EPCs caused by high glucose, which was prevented by the AMPK inhibitor compound C.ConclusionsOur results suggest that metformin could improve BM-EPC functions in STZ-induced diabetic mice, which was possibly dependent on the AMPK/eNOS pathway.Electronic supplementary materialThe online version of this article (doi:10.1186/s12933-016-0408-3) contains supplementary material, which is available to authorized users.

The correlation between number and population of bone marrow endothelial progenitor cells with bone mass and bone metabolism in the elderly

The correlation between number and population of bone marrow endothelial progenitor cells with bone mass and bone metabolism in the elderly

The correlation between number and population of bone marrow endothelial progenitor cells with bone mass and bone metabolism in the elderly

Searchable abstracts of presentations at key conferences on calcified tissues ISSN 2052-1219 (online)

Insulin sensitizers prevent fine particulate matter-induced vascular insulin resistance and changes in endothelial progenitor cell homeostasis.

Exposure to fine particular matter (PM2.5) increases the risk of developing cardiovascular disease and Type 2 diabetes. Because blood vessels are sensitive targets of air pollutant exposure, we examined the effects of concentrated ambient PM2.5 (CAP) on vascular insulin sensitivity and circulating levels of endothelial progenitor cells (EPCs), which reflect cardiovascular health. We found that CAP exposure for 9 days decreased insulin-stimulated Akt phosphorylation in the aorta of mice maintained on control diet. This change was accompanied by the induction of IL-1β and increases in the abundance of cleaved IL-18 and p10 subunit of Casp-1, consistent with the activation of the inflammasome pathway. CAP exposure also suppressed circulating levels of EPCs (Flk-1(+)/Sca-1(+) cells), while enhancing the bone marrow abundance of these cells. Although similar changes in vascular insulin signaling and EPC levels were observed in mice fed high-fat diet, CAP exposure did not exacerbate diet-induced changes in vascular insulin resistance or EPC homeostasis. Treatment with an insulin sensitizer, metformin or rosiglitazone, prevented CAP-induced vascular insulin resistance and NF-κB and inflammasome activation and restored peripheral blood and bone marrow EPC levels. These findings suggest that PM2.5 exposure induces diet-independent vascular insulin resistance and inflammation and prevents EPC mobilization, and that this EPC mobilization defect could be mediated by vascular insulin resistance. Impaired vascular insulin sensitivity may be an important mechanism underlying PM2.5-induced vascular injury, and pharmacological sensitization to insulin action could potentially prevent deficits in vascular repair and mitigate vascular inflammation due to exposure to elevated levels of ambient air pollution.

Depletion of NAD pool contributes to impairment of endothelial progenitor cell mobilization in diabetes

ObjectiveThe impaired mobilization of endothelial progenitor cells (EPCs) from bone marrow (BM) critically contributes to the diabetes-associated vascular complications. Here, we investigated the relationship between the nicotinamide phosphoribosyltransferase (NAMPT)-controlled nicotinamide adenine dinucleotide (NAD) metabolism and the impaired mobilization of BM-derived EPCs in diabetic condition. MethodsThe NAMPT-NAD pool in BM and BM-derived EPCs in wild-type (WT) and diabetic db/db mice was determined. Nicotinamide, a natural substrate for NAD biosynthesis, was administrated for 2weeks in db/db mice to examine the influence of enhancing NAD pool on BM and blood EPCs number. The modulations of stromal cell-derived factor-1α (SDF-1α) and endothelial nitric oxide synthase (eNOS) protein in BM were measured using immunoblotting. The EPCs intracellular NAMPT level and NAD concentration, as well as the blood EPCs number, were compared between 9 healthy people and 16 patients with type 2 diabetes mellitus (T2DM). The T2DM patients were treated with nicotinamide for two weeks and then the blood EPCs number was determined. Moreover, the association between blood EPCs numbers and EPCs intracellular NAD+/NAMPT protein levels in 21 healthy individuals was determined. ResultsWe found that NAD concentration and NAMPT expression in BM and BM-derived EPCs of db/db mice were significantly lower than those in WT mice BM. Enhancing NAD pool not only increased the EPCs intracellular NAD concentration and blood EPCs number, but also improved post-ischemic wound healing and blood reperfusion in db/db mice with hind-limb ischemia model. Enhancing NAD pool rescued the impaired modulations of stromal cell-derived factor-1α (SDF-1α) and endothelial nitric oxide synthase (eNOS) protein levels in db/db mice BM upon hind-limb ischemia. In addition, enhancing NAD pool significantly inhibited PARP and caspase-3 activates in db/db mice BM. The intracellular NAMPT-NAD pool was positively associated with blood EPCs number in healthy individuals. At last, we found that the EPC intracellular NAMPT and NAD+ levels were reduced in T2DM patients and enhancing NAD pool elevated the circulating blood EPCs number in T2DM patients. ConclusionOur results indicate that the depletion of NAD pool may contribute to the impairment of EPCs mobilization in diabetic condition, and imply the potential therapeutic value of nicotinamide in the prevention and treatment for cardiovascular complications of diabetes.

Effect of early rehabilitation on endothelial progenitor cells, stromal cell-derived factor alpha 1 and motor function recovery after acute cerebral infarction

Objective To observe the effects of early rehabilitation training on endothelial progenitor cells (EPCs), stromal cell-derived factor alpha 1 (SDF-1α) and motor function recovery in hemiplegic patients with acute cerebral infarction. Methods Fifty hemiplegic patients after a first acute cerebral infarction were randomly divided into a control group (n=25) and an experimental group (n=25). Both groups of patients were given routine drug therapy, while the experimental group also received early rehabilitation (within 48 hours of onset). EPCs and SDF-1α levels in peripheral blood were measured before and after one week of treatment, and Fugl-Meyer assessments and modified Barthel index scoring were conducted at admission and after three months of treatment. Results There was no difference between the 2 groups before the treatment. After a week of treatment, however, the EPC and SDF-1α values of both groups had increased, with those of the experimental group increasing significantly more than in the control group. Spearman rank correlation analysis showed that the increase in EPCs was positively correlated with the SDF-1α increment in the first week. After 3 months of treatment, the average FMA and MBI results of the experimental group were significantly better than those of the control group. Conclusion Early rehabilitation training can help to further improve the recovery of motor function for hemiplegic patients after acute cerebral infarction. This may be related to its effect in upregulating the expression of SDF-1α, thus contributing to the mobilization of EPCs in the bone marrow. Key words: Cerebral infarction; Rehabilitation; Endothelial progenitor cells; Stromal cell derived factor 1α