Bone Marrow-derived Angiogenic Cells Research Articles

Corrigendum to: Tie2-dependent knockout of HIF-1 impairs burn wound vascularization and homing of bone marrow-derived angiogenic cells.

Corrigendum to: Tie2-dependent knockout of HIF-1 impairs burn wound vascularization and homing of bone marrow-derived angiogenic cells.

Abstract 24: Hydrogen Sulfide Potentiates Bone Marrow-derived Angiogenic Progenitor Cell-mediated Ischemic Limb Angiogenesis in Diabetic Animals

Rationale: Critical hindlimb ischemia (CLI) represents an outcome of peripheral artery disease with a high incidence in diabetic patients. Recently, insufficient hydrogen sulfide (H 2 S) production has been implicated in cardiovascular disease. Objective: Explore the role of H 2 S in diabetes-induced bone marrow-derived angiogenic progenitor cells (BMAPC) dysfunction and its therapeutic effects on ischemic hindlimb injury of diabetes. Methods and Results: Diabetic BMAPCs from db/db mice showed decreased intracellular H 2 S production and blunted cystathionine γ-lyase (CSE) expression-an enzyme required for H 2 S generation. High glucose (HG) inhibited H 2 S production, migration and increased apoptosis of BMPAC that was rescued by H 2 S donor diallyl trisulfide (DATS) or overexpression of CSE. Administration DATS or local injection of diabetic BMAPCs overexpressing CSE significantly potentiated BMAPC-mediated blood flow recovery, capillary and arteriole formation, skeletal muscle architecture preservation, cell survival and decrease of perivascular infiltration of monocytes (CD68 + ) cells in ischemic skeletal muscle. Moreover, overexpression of CSE increased diabetic BMAPCs homing and engraftment in ischemic hindlimb. HG-impaired human cardiac microvascular endothelial cells (HCMVECs) tube formation and migration were rescued by DATS or overexpression of CSE. Mechanistically, HG increased threonine-495 phosphorylation of eNOS (eNOS-pT495) and inhibited nitric oxide (NO) production in HCMVECs which were rescued by DATS or overexpression of CSE. Silencing CSE by siRNA impaired tube formation and increased eNOS-pT495 expression in HCMVECs. Finally, HG-treated BMAPCs impaired mouse microvascular endothelial cell tube formation that was rescued by DATS. Conclusions: Our data suggests that CSE downregulation-induced H 2 S insufficient plays a critical role in diabetes-mediated BMAPC dysfunction. Administration of DATS or overexpression of CSE improves diabetic BMAPC-mediated angiogenesis/neovascularization via, at least partially, eNOS inactivation/NO reduction pathways. Our data indicate that H 2 S and overexpression of CSE in diabetic BMAPCs may open novel avenues for cell-based therapeutics of CLI in diabetic patients.

G-Protein-coupled receptors as potential drug candidates in preeclampsia: targeting the relaxin/insulin-like family peptide receptor 1 for treatment and prevention.

Important roles for G-protein-coupled receptors (GPCRs) have been identified in the maternal physiological adaptations to pregnancy and in the pathogenesis of preeclampsia. On this basis, GPCRs are potential therapeutic targets for preeclampsia. In this review, vasopressin and apelin are initially considered in this context before the focus on the hormone relaxin and its cognate receptor, the relaxin/insulin-like family peptide receptor 1 (RXFP1). Based on both compelling scientific rationale and a promising safety profile, the relaxinligand-receptor system is comprehensively evaluated as a potential therapeutic endpoint in preeclampsia. The published literature relating to the topic was searchedthroughJanuary 2016 using PubMed. Relaxin is a peptide hormone secreted by the corpus luteum; it circulates in the luteal phase and during pregnancy. Activation of RXFP1 is vasodilatory; thus, relaxin supplementation is expected to at least partly restore the fundamental vasodilatory changes of normal pregnancy, thereby alleviating maternal organ hypoperfusion, which is a major pathogenic manifestation of severe preeclampsia. Specifically, by exploiting its pleiotropic hemodynamic attributes in preeclampsia, relaxin administration is predicted to (i) reverse robust arterial myogenic constriction; (ii) blunt systemic and renal vasoconstriction in response to activation of theangiotensin II receptor, type 1; (iii) mollify the action of endogenous vasoconstrictors on uterine spiral arteries with failed remodeling and retained smooth muscle; (iv) increase arterial compliance; (v) enhance insulin-mediated glucose disposal by promoting skeletal muscle vasodilation and (vi) mobilize and activate bone marrow-derived angiogenic progenitor cells, thereby repairing injured endothelium and improving maternal vascularity in organs such as breast, uterus, pancreas, skin and fat. By exploiting its pleiotropic molecular attributes in preeclampsia, relaxin supplementation is expected to (i) enhance endothelial nitric oxide synthesis and bioactivity, as well as directly reduce vascular smooth muscle cytosolic calcium, thus promoting vasodilation; (ii) improve the local angiogenic balance by augmenting arterial vascular endothelial and placental growth factor (VEGF and PLGF) activities; (iii) ameliorate vascular inflammation; (iv) enhance placental peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PCG1α) expression, and hence, peroxisome proliferator-activated receptor gamma(PPAR-γ) activity and (v) confer cytotrophoblast and endothelial cytoprotection. Insofar as impaired endometrial maturation (decidualization) predisposes to the development of preeclampsia, relaxin administration in the late secretory phase and during early pregnancy would be anticipated to improve decidualization, and hence trophoblast invasion and spiral artery remodeling, thereby reducing the risk of preeclampsia. Relaxin has a favorable safety profile both in the non-pregnant condition and during pregnancy. There is a strong scientific rationale for RXFP1 activation in severe preeclampsia by administration of relaxin, relaxin analogs or small molecule mimetics, in order to mollify the disease pathogenesis for safe prolongation of pregnancy, thus allowing time for more complete fetal maturation, which is a primary therapeutic endpoint in treating the disease. In light of recent data implicating deficient or defective decidualization as a potential etiological factor in preeclampsia and the capacity of relaxin to promote endometrial maturation, the prophylactic application of relaxin to reduce the risk of preeclampsia is a plausible therapeutic approach to consider. Finally, given its pleiotropic and beneficial attributes particularly in the cardiovascular system, relaxin, although traditionally considered as a 'pregnancy' hormone, is likely to prove salutary for several disease indications in the non-pregnant population.

Aging impairs ischemia-induced neovascularization by attenuating the mobilization of bone marrow-derived angiogenic cells

BackgroundAging is associated with impaired ischemia-induced neovascularization. However, the effects of aging on bone marrow-derived angiogenic cell (BMDAC)-mediated vasculogenesis and on angiogenesis at the ischemic sites remain incompletely understood. Methods and resultsTwo- and 24-month old male C57Bl/6J mice were subjected to hindlimb ischemia. The levels of Sca1+/CXCR4+ BMDACs were determined post-ischemia by flow cytometry. In young mice, ischemia increased Sca1+/CXCR4+ BMDAC levels in the bone marrow and spleen at day 3 (p<0.001) and in the circulating blood at day 7 (p<0.01) post-ischemia. However, ischemia-induced elevation of progenitor cells was attenuated in the bone marrow, spleen and blood of old mice despite a preserved HIF-1α-mediated angiogenic response in the ischemic tissues. Irradiated young recipient mice engrafted with old bone marrow displayed reduced levels of Sca1+/CXCR4+ BMDACs in the bone marrow and circulating blood post-ischemia compared to recipients with young bone marrow. Ex vivo cultured BMDACs from old mice exhibited reduced SDF-1-stimulated migration (p<0.01) and a decrease in JAK-2 and AKT activation. However, the intrinsic angiogenic function of BMDACs, including VEGF secretion and promotion of endothelial cell tubule formation, was preserved with aging. Furthermore, facilitated mobilization of old bone marrow-derived mononuclear cells to the ischemic hindlimb by intramuscular injection enhanced ischemia-induced neovascularization in old mice in vivo (p<0.001). ConclusionsThe age-related impairment in ischemia-induced neovascularization is largely attributable to a marked attenuation of BMDAC mobilization with a preservation of intrinsic angiogenic function with age.

Targeting hypoxia-inducible factor 1 to stimulate tissue vascularization

When tissue perfusion is impaired, the resulting reduction in O2 availability activates hypoxia-inducible factor 1 (HIF-1), which mediates increased transcription of genes encoding multiple angiogenic factors including vascular endothelial growth...

METHYLGLYOXAL-DERIVED ADVANCED GLYCATION END-PRODUCTS PRODUCED AFTER MYOCARDIAL INFARCTION CONTRIBUTE TO NEGATIVE CARDIAC REMODELLING

METHYLGLYOXAL-DERIVED ADVANCED GLYCATION END-PRODUCTS PRODUCED AFTER MYOCARDIAL INFARCTION CONTRIBUTE TO NEGATIVE CARDIAC REMODELLING

Number and function of bone-marrow derived angiogenic cells and coronary flow reserve in women without obstructive coronary artery disease: a substudy of the NHLBI-sponsored Women's Ischemia Syndrome Evaluation (WISE).

BackgroundIn women with ischemia and no obstructive coronary artery disease, the Women's Ischemic Syndrome Evaluation (WISE) observed that microvascular coronary dysfunction (MCD) is the best independent predictor of adverse cardiovascular events. Since coronary microvascular tone is regulated in part by endothelium, we hypothesized that circulating endothelial cells (CEC), which reflect endothelial injury, and the number and function of bone-marrow derived angiogenic cells (BMDAC), which could help repair damaged endothelium, may serve as biomarkers for decreased coronary flow reserve (CFR) and MCD.MethodsWe studied 32 women from the WISE cohort. CFR measurements in response to intracoronary adenosine were taken as an index of MCD. We enumerated BMDAC colonies and CEC in peripheral blood samples. BMDAC function was assessed by assay of migration of CD34+ cells toward SDF-1 and measurement of bioavailable nitric oxide (NO). These findings were compared with a healthy reference group and also entered into a multivariable model with CFR as the dependent variable.ResultsCompared with a healthy reference group, women with MCD had lower numbers of BMDAC colonies [16 (0, 81) vs. 24 (14, 88); P = 0.01] and NO [936 (156, 1875) vs. 1168 (668, 1823); P = 0.02]. Multivariable regression analysis showed strong correlation of CFR to the combination of BMDAC colony count and CD34+ cell function (migration and NO) (R2 = 0.45; P<0.05).ConclusionsThe BMDAC function and numbers of BMDAC colonies are decreased in symptomatic women with MCD and are independently associated with CFR. These circulating cells may provide mechanistic insights into MCD in women with ischemia.

MicroRNA miR-27b Rescues Bone Marrow–Derived Angiogenic Cell Function and Accelerates Wound Healing in Type 2 Diabetes Mellitus

Vascular precursor cells with angiogenic potentials are important for tissue repair, which is impaired in diabetes mellitus. MicroRNAs are recently discovered key regulators of gene expression, but their role in vascular precursor cell-mediated angiogenesis in diabetes mellitus is unknown. We tested the hypothesis that the microRNA miR-27b rescues impaired bone marrow-derived angiogenic cell (BMAC) function in vitro and in vivo in type 2 diabetic mice. BMACs from adult male type 2 diabetic db/db and from normal littermate db/+ mice were used. miR-27b expression was decreased in db/db BMACs. miR-27b mimic improved db/db BMAC function, including proliferation, adhesion, tube formation, and delayed apoptosis, but it did not affect migration. Elevated thrombospondin-1 (TSP-1) protein in db/db BMACs was suppressed on miR-27b mimic transfection. Inhibition of miR-27b in db/+ BMACs reduced angiogenesis, which was reversed by TSP-1 small interfering RNA (siRNA). miR-27b suppressed the pro-oxidant protein p66(shc) and mitochondrial oxidative stress, contributing to its protection of BMAC function. miR-27b also suppressed semaphorin 6A to improve BMAC function in diabetes mellitus. Luciferase binding assay suggested that miR-27b directly targeted TSP-1, TSP-2, p66(shc), and semaphorin 6A. miR-27b improved topical cell therapy of diabetic BMACs on diabetic skin wound closure, with a concomitant augmentation of wound perfusion and capillary formation. Normal BMAC therapy with miR-27b inhibition demonstrated reduced efficacy in wound closure, perfusion, and capillary formation. Local miR-27b delivery partly improved wound healing in diabetic mice. miR-27b rescues impaired BMAC angiogenesis via TSP-1 suppression, semaphorin 6A expression, and p66shc-dependent mitochondrial oxidative stress and improves BMAC therapy in wound healing in type 2 diabetic mice.

Thrombospondin-1/CD36 pathway contributes to bone marrow-derived angiogenic cell dysfunction in type 1 diabetes via Sonic hedgehog pathway suppression

Refractory wounds in diabetic patients present a significant clinical problem. Sonic hedgehog (SHH), a morphogenic protein central to wound repair, is deficient in diabetes. Regulation of SHH in wound healing is poorly understood. We hypothesize that thrombospondin-1 (TSP-1), through its receptor CD36, contributes to the SHH signaling defect in bone marrow-derived angiogenic cells (BMACs) in type 1 diabetic mice. Isolated BMACs from TSP-1-knockout mice demonstrated improved tube formation, migration, and adhesion in parallel with active SHH signaling. BMACs from STZ-induced type 1 diabetic mice showed significantly impaired Matrigel tube formation (n = 5; P < 0.05 vs. control), which was rescued by TSP-1 depletion (n = 5; P < 0.05 STZ-TSP-1(-/-) vs. STZ-WT) or exogenous SHH (20 mg/l, 24 h, n = 4; P < 0.05 vs. STZ-control). The expression of CD36 was elevated in BMACs from STZ mice (n = 4; P < 0.05). SHH signaling was significantly higher in BMACs from TSP-1(-/-) mice and TSP-1 receptor CD36-knockout mice (n = 6; P < 0.05 vs. WT) but not CD47-knockout mice (n = 3; P > 0.05 vs. WT). The impairment of recombinant human TSP-1 (2.2 nM, 24 h) on BMAC Matrigel tube formation was delayed significantly by CD36 deletion (n = 5; P < 0.05). CD36(-/-) BMACs demonstrated better tube formation under both normal and diabetic conditions with active SHH signaling (n = 4; P < 0.05 vs. WT BMACs). In conclusion, The TSP-1/CD36 pathway contributes to the SHH signaling defect, resulting in BMAC dysfunction in type 1 diabetic mice.

Combination of HIF-1α gene transfection and HIF-1-activated bone marrow-derived angiogenic cell infusion improves burn wound healing in aged mice

Impaired burn wound healing in the elderly represents a major clinical problem. Hypoxia-inducible factor-1 (HIF-1) is a transcriptional activator that orchestrates the cellular response to hypoxia. Its actions in dermal wounds promote angiogenesis and improve healing. In a murine burn wound model, aged mice had impaired wound healing associated with reduced levels of HIF-1. When gene therapy with HIF-1 alone did not correct these deficits, we explored the potential benefit of HIF-1 gene therapy combined with the intravenous infusion of bone marrow-derived angiogenic cells (BMDACs) cultured with dimethyloxalylglycine (DMOG). DMOG is known to reduce oxidative degradation of HIF-1. The mice treated with a plasmid DNA construct expressing a stabilized mutant form of HIF-1α (CA5-HIF-1α)+BMDACs had more rapid wound closure. By day 17, there were more mice with completely closed wounds in the treated group (χ(2), P=0.05). The dermal blood flow measured by laser Doppler showed significantly increased wound perfusion on day 11. Homing of BMDACs to the burn wound was dramatically enhanced by CA5-HIF-1α gene therapy. HIF-1α mRNA expression in the burn wound was increased after transfection with CA5-HIF-1α plasmid. Our findings offer insight into the pathophysiology of burns in the elderly and point to potential targets for developing new therapeutic strategies.

Oxidative Stress–Mediated Thrombospondin-2 Upregulation Impairs Bone Marrow–Derived Angiogenic Cell Function in Diabetes Mellitus

Circulating angiogenic cells play an essential role in angiogenesis but are dysfunctional in diabetes mellitus characterized by excessive oxidative stress. We hypothesize that oxidative stress-mediated upregulation of thrombospondin-2 (TSP-2), a potent antiangiogenic protein, contributes to diabetic bone marrow-derived angiogenic cell (BMAC) dysfunction. BMACs were isolated from adult male type 2 diabetic db/db mice and control db/+ (C57BLKS/J) mice. In Matrigel tube formation assay, angiogenic function was impaired in diabetic BMACs, accompanied by increased oxidative stress and nicotinamide adenine dinucleotide phosphate oxidase activity. BMAC angiogenic function was restored by overexpression of dominant negative Rac1 or by overexpression of manganese superoxide dismutase. TSP-2 mRNA and protein were both significantly upregulated in diabetic BMACs, mediated by increased oxidative stress as shown by a decrease in TSP-2 level after overexpression of dominant negative Rac1 or manganese superoxide dismutase. Silencing TSP-2 by its small interfering RNA in diabetic BMACs improved BMAC function in tube formation, adhesion, and migration assays. Notably, the upregulation of TSP-2 was also found in BMACs from streptozotocin-induced type 1 diabetic mice, and normal BMACs with high glucose treatment. let-7f, a microRNA which has been related to endothelial angiogenic function, is found to play key role in TSP-2 increase, but let-7f did not directly interact with TSP-2 mRNA. The upregulation of TSP-2 mediated by increased oxidative stress contributes to angiogenesis dysfunction in diabetic BMACs.

Diminazene Attenuates Pulmonary Hypertension and Improves Angiogenic Progenitor Cell Functions in Experimental Models

Studies have demonstrated that angiotensin-converting enzyme 2 (ACE2) plays a protective role against lung diseases, including pulmonary hypertension (PH). Recently, an antitrypanosomal drug, diminazene aceturate (DIZE), was shown to exert an "off-target" effect of enhancing the enzymatic activity of ACE2 in vitro. To evaluate the pharmacological actions of DIZE in experimental models of PH. PH was induced in male Sprague Dawley rats by monocrotaline, hypoxia, or bleomycin challenge. Subsets of animals were simultaneously treated with DIZE. In a separate set of experiments, DIZE was administered after 3 weeks of PH induction to determine whether the drug could reverse PH. DIZE treatment significantly prevented the development of PH in all of the animal models studied. The protective effects were associated with an increase in the vasoprotective axis of the lung renin-angiotensin system, decreased inflammatory cytokines, improved pulmonary vasoreactivity, and enhanced cardiac function. These beneficial effects were abolished by C-16, an ACE2 inhibitor. Initiation of DIZE treatment after the induction of PH arrested disease progression. Endothelial dysfunction represents a hallmark of PH pathophysiology, and growing evidence suggests that bone marrow-derived angiogenic progenitor cells contribute to endothelial homeostasis. We observed that angiogenic progenitor cells derived from the bone marrow of monocrotaline-challenged rats were dysfunctional and were repaired by DIZE treatment. Likewise, angiogenic progenitor cells isolated from patients with PH exhibited diminished migratory capacity toward the key chemoattractant stromal-derived factor 1α, which was corrected by in vitro DIZE treatment. Our results identify a therapeutic potential of DIZE in PH therapy.

Cancer–stromal cell interactions mediated by hypoxia-inducible factors promote angiogenesis, lymphangiogenesis, and metastasis

Interactions between cancer cells and stromal cells, including blood vessel endothelial cells (BECs), lymphatic vessel endothelial cells (LECs), bone marrow-derived angiogenic cells (BMDACs) and other bone marrow-derived cells (BMDCs) play important roles in cancer progression. Intratumoral hypoxia, which affects both cancer and stromal cells, is associated with a significantly increased risk of metastasis and mortality in many human cancers. Recent studies have begun to delineate the molecular mechanisms underlying the effect of intratumoral hypoxia on cancer progression. Reduced O2 availability induces the activity of hypoxia-inducible factors (HIFs), which activate the transcription of target genes encoding proteins that play important roles in many critical aspects of cancer biology. Included among these are secreted factors, including angiopoietin 2, angiopoietin-like 4, placental growth factor, platelet-derived growth factor B, stem cell factor (kit ligand), stromal-derived factor 1, and vascular endothelial growth factor. These factors are produced by hypoxic cancer cells and directly mediate functional interactions with BECs, LECs, BMDACs and other BMDCs that promote angiogenesis, lymphangiogenesis, and metastasis. In addition, lysyl oxidase (LOX) and LOX-like proteins, which are secreted by hypoxic breast cancer cells, remodel extracellular matrix in the lungs, which leads to BMDC recruitment and metastatic niche formation.

Diabetes and aging: a different phenotypic commitment of circulating and resident stem cells?

Atherosclerosis is a vascular disease largely attributed to chronic vascular injury, and its clinical manifestations appear more frequently in aged subjects. Accumulation of vascular smooth muscle cells in the tunica intima plays a major role in the pathogenesis of atherosclerosis. Arterial smooth muscle cells are heterogeneous even in the normal vessel wall and display more marked different phenotypes in pathological conditions. Smooth muscle cells in atherosclerotic plaques display a de-differentiated or ‘‘synthetic’’ phenotype compared to a ‘‘contractile’’ phenotype in the normal media. Aorta stiffens with age and other cardiovascular risk factors. In particular, diabetes-induced activation of the renin–angiotensin system increases the expression of angiotensin II, further increasing aortic calcification and stiffness. Thus, alterations of aortic and carotid walls in patients with diabetes were traditionally considered a sort of ‘‘accelerated aging.’’ In the last years, the contribution of stem cells to atherosclerosis has been highlighted. Bone marrow and peripheral blood-derived endothelial and vascular smooth muscle cell resident progenitors both contribute to vascular remodeling during atherogenetic process and aging [1]. Both circulating and resident progenitor cells have been evocated to contribute to the response of the adult arterial wall to damage. Chronic treatment with bone marrow-derived progenitor cells from young non-atherosclerotic ApoE/ mice prevents atherosclerosis progression in ApoE/ recipients despite persistent hypercholesterolemia, whereas bone marrow-derived progenitor cells from older ApoE/ mice with atherosclerosis were much less effective [2]. These findings suggest that the progressive bone marrow-derived progenitor cells deficit may contribute to the development of atherosclerosis. Nevertheless, atherosclerotic lesions are characterized from the increase of stem cell markerexpressing cells, and macroscopically normal aortas from human and rat aged donors show an increased number of VEGFR-1 and c-kit cells in the thickened intima [3]. Also, diabetes alters the function of circulating progenitor cells. Depletion of bone marrow-derived angiogenic cell populations may further promote atherogenesis and aortic calcification in patients with diabetes mellitus [4]. In multivariable analyses, the increase in colony-forming units from endothelial progenitor cells was associated with the decrease in coronary artery and abdominal aortic calcification [5]. These changes were not associated with changes in CD34 expression, suggesting that a decreased angiogenic potential contributes to the development of human atherosclerosis. Moreover, decreasing colonyforming capacity associated with the progressive increase of calcification scores [5]. Recently, it has been reported that diabetes mellitus patients had significantly higher expression of osteocalcin and bone alkaline phosphatase on circulating VEGFR-2/CD34 progenitor cells than control subjects [6]. Moreover, cultured VEGFR-2/CD34 cells from diabetes mellitus patients formed structures highly suggestive of calcified nodules, strongly suggesting that circulating progenitor cells from diabetic patients show a drift toward a pro-calcific phenotype that may be driven by inflammatory signals in response to injury [6], similarly to that observed in non-vascular tissues [7]. Monocyte– macrophage recruitment is a crucial step for a correct angiogenesis, and this mechanism is mainly mediated by VEGFR-1, that favors the increase of vessel lumen, vessel Communicated by Massimo Federici.

HIF-1α gene therapy combined with HIF-1 activated bone marrow-derived angiogenic cell (BMDAC) therapy improves burn wound healing in aged mice

HIF-1α gene therapy combined with HIF-1 activated bone marrow-derived angiogenic cell (BMDAC) therapy improves burn wound healing in aged mice

Tie2-dependent knockout of HIF-1 impairs burn wound vascularization and homing of bone marrow-derived angiogenic cells

Hypoxia-inducible factor 1 (HIF-1) is a heterodimer composed of HIF-1α and HIF-1β subunits. HIF-1 is known to promote tissue vascularization by activating the transcription of genes encoding angiogenic factors, which bind to receptors on endothelial cells (ECs) and bone marrow-derived angiogenic cells (BMDACs). In this study, we analysed whether HIF-1 activity in the responding ECs and BMDACs is also required for cutaneous vascularization during burn wound healing. We generated mice with floxed alleles at the Hif1a or Arnt locus encoding HIF-1α and HIF-1β, respectively. Expression of Cre recombinase was driven by the Tie2 gene promoter, which is expressed in ECs and bone marrow cells. Tie2Cre(+) and Tie2Cre(-) mice were subjected to burn wounds of reproducible diameter and depth. Deficiency of HIF-1α or HIF-1β in Tie2-lineage cells resulted in delayed wound closure, reduced vascularization, decreased cutaneous blood flow, impaired BMDAC mobilization, and decreased BMDAC homing to burn wounds. HIF-1 activity in Tie2-lineage cells is required for the mobilization and homing of BMDACs to cutaneous burn wounds and for the vascularization of burn wound tissue.

Burn wound homing of bone marrow-derived angiogenic cells is impaired by conditional knock out of the hypoxia-inducible factor 1beta gene

Burn wound homing of bone marrow-derived angiogenic cells is impaired by conditional knock out of the hypoxia-inducible factor 1beta gene

Metabolic reprogramming by HIF-1 promotes the survival of bone marrow–derived angiogenic cells in ischemic tissue

AbstractA major obstacle to using bone marrow cell-based therapies for ischemic cardiovascular disease is that transplanted cells must survive in an ischemic microenvironment characterized by low oxygen, glucose, and pH. We demonstrate that treatment of bone marrow-derived angiogenic cells (BMDACs) with dimethyloxalylglycine, an α-ketoglutarate antagonist that induces hypoxia-inducible factor 1 (HIF-1) activity, results in metabolic reprogramming of these cells, with increased glucose uptake, decreased O2 consumption, increased lactate production, decreased reactive oxygen species, and increased intracellular pH. These effects are dependent on HIF-1, which transactivates target genes encoding metabolic enzymes and membrane transporters. Dimethyloxalylglycine-treated BMDACs have a significant survival advantage under conditions of low O2 and low pH ex vivo and in ischemic tissue. Combined HIF-1α-based gene and cell therapy reduced tissue necrosis even when BMDAC donors and ischemic recipient mice were 17 months old, suggesting that this approach may have therapeutic utility in elderly patients with critical limb ischemia.

Aging impairs the mobilization and homing of bone marrow-derived angiogenic cells to burn wounds

Impaired wound healing in the elderly represents a major clinical problem. Delineating the cellular and molecular mechanisms by which aging impairs wound healing may lead to the development of improved treatment strategies for elderly patients with non-healing wounds. Neovascularization is an essential step in wound healing, and bone marrow-derived angiogenic cells (BMDACs) play an important role in vascularization. Using a mouse full-thickness burn wound model, we demonstrate that perfusion and vascularization of burn wounds were impaired by aging and were associated with dramatically reduced mobilization of BMDACs bearing the cell surface molecules CXCR4 and Sca1. Expression of stromal-derived factor 1 (SDF-1), the cytokine ligand for CXCR4, was significantly decreased in peripheral blood and burn wounds of old mice. Expression of hypoxia-inducible factor (HIF)-1α was detected in burn wounds from young (2-month-old), but not old (2-year-old), mice. When BMDACs from young donor mice were injected intravenously, homing to burn wound tissue was impaired in old recipient mice, whereas the age of the BMDAC donor mice had no effect on homing. Our results indicate that aging impairs burn wound vascularization by impairing the mobilization of BMDACs and their homing to burn wound tissue as a result of impaired HIF-1 induction and SDF-1 signaling.

Hypoxia-inducible factor-1-dependent mechanisms of vascularization and vascular remodelling

The vascular system delivers oxygen and nutrients to every cell in the vertebrate organism. Hypoxia-inducible factor 1 (HIF-1) is a master regulator of hypoxic/ischaemic vascular responses, driving transcriptional activation of hundreds of genes involved in vascular reactivity, angiogenesis, arteriogenesis, and the mobilization and homing of bone marrow-derived angiogenic cells. This review will focus on the pivotal role of HIF-1 in vascular homeostasis, the involvement of HIF-1 in vascular diseases, and recent advances in targeting HIF-1 for therapy in preclinical models.