Downregulated calmodulin expression contributes to endothelial cell impairment in diabetes

Endothelial dysfunction, a central hallmark of cardiovascular pathogenesis in diabetes mellitus, is characterized by impaired endothelial nitric oxide synthase (eNOS) and NO bioavailability. However, the underlying mechanisms remain unclear. Here in this study, we aimed to identify the role of calmodulin (CaM) in diabetic eNOS dysfunction. Human umbilical vein endothelial cells and murine endothelial progenitor cells (EPCs) treated with high glucose (HG) exhibited downregulated CaM mRNA/protein and vascular endothelial growth factor (VEGF) expression with impeded eNOS phosphorylation and cell migration/tube formation. These perturbations were reduplicated in CALM1-knockdown cells but prevented in CALM1-overexpressing cells. EPCs from type 2 diabetes animals behaved similarly to HG-treated normal EPCs, which could be rescued by CALM1-gene transduction. Consistently, diabetic animals displayed impaired eNOS phosphorylation, endothelium-dependent dilation, and CaM expression in the aorta, as well as deficient physical interaction of CaM and eNOS in the gastrocnemius. Local CALM1 gene delivery into a diabetic mouse ischemic hindlimb improved the blunted limb blood perfusion and gastrocnemius angiogenesis, and foot injuries. Diabetic patients showed insufficient foot microvascular autoregulation, eNOS phosphorylation, and NO production with downregulated CaM expression in the arterial endothelium, and abnormal CALM1 transcription in genome-wide sequencing analysis. Therefore, our findings demonstrated that downregulated CaM expression is responsible for endothelium dysfunction and angiogenesis impairment in diabetes, and provided a novel mechanism and target to protect against diabetic endothelial injury.

Muscle progenitor cells are required for skeletal muscle regeneration and prevention of adipogenesis after limb ischemia

Skeletal muscle injury in peripheral artery disease (PAD) has been attributed to vascular insufficiency, however evidence has demonstrated that muscle cell responses play a role in determining outcomes in limb ischemia. Here, we demonstrate that genetic ablation of Pax7+ muscle progenitor cells (MPCs) in a model of hindlimb ischemia (HLI) inhibited muscle regeneration following ischemic injury, despite a lack of morphological or physiological changes in resting muscle. Compared to control mice (Pax7WT), the ischemic limb of Pax7-deficient mice (Pax7Δ) was unable to generate significant force 7 or 28 days after HLI. A significant increase in adipose was observed in the ischemic limb 28 days after HLI in Pax7Δ mice, which replaced functional muscle. Adipogenesis in Pax7Δ mice corresponded with a significant increase in PDGFRα+ fibro/adipogenic progenitors (FAPs). Inhibition of FAPs with batimastat decreased muscle adipose but increased fibrosis. In vitro, Pax7Δ MPCs failed to form myotubes but displayed increased adipogenesis. Skeletal muscle from patients with critical limb threatening ischemia displayed increased adipose in more ischemic regions of muscle, which corresponded with fewer satellite cells. Collectively, these data demonstrate that Pax7+ MPCs are required for muscle regeneration after ischemia and suggest that muscle regeneration may be an important therapeutic target in PAD.

microRNA-29a Regulates ADAM12 Through Direct Interaction With ADAM12 mRNA and Modulates Postischemic Perfusion Recovery

Background

Peripheral artery disease is caused by atherosclerotic occlusion of vessels outside the heart and most commonly affects vessels of the lower extremities. Angiogenesis is a part of the postischemic adaptation involved in restoring blood flow in peripheral artery disease. Previously, in a murine hind limb ischemia model of peripheral artery disease, we identified ADAM12 (a disintegrin and metalloproteinase gene 12) as a key genetic modifier of postischemic perfusion recovery. However, less is known about ADAM12 regulation in ischemia. MicroRNAs are a class of small, noncoding, single‐stranded RNAs that regulate gene expression primarily through transcriptional repression of messenger RNA (mRNA). We showed microRNA‐29a (miR‐29a) modulates ADAM12 expression in the setting of diabetes and ischemia. However, how miR‐29a modulates ADAM12 is not known. Moreover, the physiological effects of miR‐29a modulation in a nondiabetic setting is not known.

Methods and Results

We overexpressed or inhibited miR‐29a in ischemic mouse gastrocnemius and tibialis anterior muscles, and quantified the effect on perfusion recovery, ADAM12 expression, angiogenesis, and skeletal muscle regeneration. In addition, using RNA immunoprecipitation–based anti‐miR competitive assay, we investigated the interaction of miR‐29a and ADAM12 mRNA in mouse microvascular endothelial cell, skeletal muscle, and human endothelial cell lysates. Ectopic expression of miR‐29a in ischemic mouse hind limbs decreased ADAM12 mRNA expression, increased skeletal muscle injury, decreased skeletal muscle function, and decreased angiogenesis and perfusion recovery, with no effect on skeletal muscle regeneration and myofiber cross‐sectional area following hind limb ischemia. RNA immunoprecipitation–based anti‐miR competitive assay studies showed miR‐29a antagomir displaced miR‐29a and ADAM12 mRNA from the AGO‐2 (Argonaut‐2) complex in a dose dependent manner.

Conclusions

Taken together, the data show miR‐29a suppresses ADAM12 expression by directly binding to its mRNA, resulting in impaired skeletal muscle function, angiogenesis, and poor perfusion. Hence, elevated levels of miR‐29a, as seen in diabetes and aging, likely contribute to vascular pathology, and modulation of miR‐29a could be a therapeutic target.

Resveratrol Promotes Angiogenesis in a FoxO1-Dependent Manner in Hind Limb Ischemia in Mice

Critical limb ischemia (CLI) is a severe form of peripheral artery diseases (PAD) and seriously endangers the health of people. Therapeutic angiogenesis represents an important treatment strategy for CLI; various methods have been applied to enhance collateral circulation. However, the current development drug therapy to promote angiogenesis is limited. Resveratrol (RSV), a polyphenol compound extracted from plants, has various properties such as anti-oxidative, anti-inflammatory and anti-cancer effects. Whether RSV exerts protective effects on CLI remains elusive. In the current study, we demonstrated that oral intake of RSV significantly improved hind limb ischemia in mice, and increased the expression of phosphorylated Forkhead box class-O1 (FoxO1). RSV treatment in human umbilical vein endothelial cells (HUVECs) could increase the phosphorylation of FoxO1 and its cytoplasmic re-localization to promote angiogenesis. Then we manipulated FoxO1 in HUVECs to further verify that the effect of RSV on angiogenesis is in a FoxO1-dependent manner. Furthermore, we performed metabolomics to screen the metabolic pathways altered upon RSV intervention. We found that the pathways of pyrimidine metabolism, purine metabolism, as well as alanine, aspartate and glutamate metabolism, were highly correlated with the beneficial effects of RSV on the ischemic muscle. This study provides a novel direction for the medical therapy to CLI.

Plicosepalus acacia Extract and Its Major Constituents, Methyl Gallate and Quercetin, Potentiate Therapeutic Angiogenesis in Diabetic Hind Limb Ischemia: HPTLC Quantification and LC-MS/MS Metabolic Profiling

Plicosepalus acacia (Fam. Loranthaceae) has been reported to possess hypoglycemic, antioxidant, antimicrobial, and anti-inflammatory effects. Liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) analysis revealed the presence of a high content of polyphenolic compounds that are attributed to the therapeutic effects of the crude extract. In addition, methyl gallate and quercetin were detected as major phytomedicinal agents at concentrations of 1.7% and 0.062 g%, respectively, using high-performance thin layer chromatography (HPTLC). The present study investigated the effect of the P. acacia extract and its isolated compounds, methyl gallate and quercetin, on hind limb ischemia induced in type 1 diabetic rats. Histopathological examination revealed that treatment with P. acacia extract, methyl gallate, and quercetin decreased degenerative changes and inflammation in the ischemic muscle. Further biochemical assessment of the hind limb tissue showed decreased oxidative stress, increased levels of nitric oxide and endothelial nitric oxide synthase (eNOS), and enhancement of the levels of heme oxygenase-1 (HO-1) and vascular endothelial growth factor (VEGF) in the groups treated with methyl gallate and quercetin. Expression levels of hypoxia inducible factor-1 alpha (HIF-1α), VEGF, fibroblast growth factor-2 (FGF-2), and miR-146a were upregulated in the muscle tissue of methyl gallate- and quercetin-treated groups along with downregulation of nuclear factor kappa B (NF-κB). In conclusion, P. acacia extract and its isolated compounds, methyl gallate and quercetin, mediated therapeutic angiogenesis in diabetic hind limb ischemia.

Treatment with adipose-derived regenerative cells enhances ischemia-induced angiogenesis via exosomal microRNA delivery in mice

Adipose-derived regenerative cells (ADRCs), mesenchymal stem/progenitor cells from subcutaneous adipose tissue, have been shown to stimulate angiogenesis in hind limb ischemia, an effect attributed to paracrine action on endothelial cells (ECs) in mice. Despite promising therapeutic effects, the relevant molecules promoting neovascularization in this setting have not been fully elucidated. Extracellular vesicles, crucial mediators of intercellular communication, are recognized as a new therapeutic modality for regenerative medicine. Here, we found that GW4869, an exosome biogenesis inhibitor targeting neutral sphingomyelinase, impaired ADRCs-mediated angiogenesis and improvement of blood perfusion in a murine hind limb ischemia model. In addition, while the supernatant of ADRCs induced murine EC migration, this effect was attenuated by pre-treatment with GW4869. RNA analysis revealed that treatment of ADRCs with GW4869 reduced the expression of microRNA-21 (miR-21), miR-27b, miR-322, and let-7i in ADRCs-derived exosomes. Furthermore, the exosomes derived from GW4869-treated ADRCs induced the expression of the miR-21 targets Smad7 and Pten, and the miR-322 target Cul2, in ECs. These findings suggest that several miRNAs in ADRCs-derived exosomes contribute to angiogenesis and improvement of blood perfusion in a murine hind limb ischemia model.

Oroxylin a Attenuates Limb Ischemia by Promoting Angiogenesis via Modulation of Endothelial Cell Migration

Oroxylin A (OA) has been shown to simultaneously increase coronary flow and provide a strong anti-inflammatory effect. In this study, we described the angiogenic properties of OA. OA treatment accelerated perfusion recovery, reduced tissue injury, and promoted angiogenesis after hindlimb ischemia (HLI). In addition, OA regulated the secretion of multiple cytokines, including vascular endothelial growth factor A (VEGFA), angiopoietin-2 (ANG-2), fibroblast growth factor-basic (FGF-2), and platelet derived growth factor BB (PDGF-BB). Specifically, those multiple cytokines were involved in cell migration, cell population proliferation, and angiogenesis. These effects were observed at 3, 7, and 14 days after HLI. In skeletal muscle cells, OA promoted the release of VEGFA and ANG-2. After OA treatment, the conditioned medium derived from skeletal muscle cells was found to significantly induce endothelial cell (EC) proliferation. OA also induced EC migration by activating the Ras homolog gene family member A (RhoA)/Rho-associated coiled-coil kinase 2 (ROCK-II) signaling pathway and the T-box20 (TBX20)/prokineticin 2 (PROK2) signaling pathway. In addition, OA was able to downregulate the number of macrophages and neutrophils, along with the secretion of interleukin-1β, at 3 days after HLI. These results expanded current knowledge about the beneficial effects of OA in angiogenesis and blood flow recovery. This research could open new directions for the development of novel therapeutic intervention for patients with peripheral artery disease (PAD).

Ischemic tissue released microvesicles induce monocyte reprogramming and increase tissue repair by a tissue factor-dependent mechanism

AIMS

Despite increasing evidence that monocytes may acquire endothelial features, it remains unclear how monocytes participate in angiogenesis after ischemic damage. We investigated whether ischemic cells can release microvesicles (MVs) and promote neovascularisation in a model of peripheral artery disease (PAD).

METHODS AND RESULTS

To model PAD we used an in vivo experimental model of hind limb ischemia (HLI) in mice. MVs were isolated from the ischemic muscle and from peripheral blood at different times after unilateral femoral artery ligation. MVs were phenotypically characterized to identify cell origin. HLI in mice induced the release of MVs with a much higher content of tissue factor (TF) than non-HLI control mice both in the MVs isolated from the affected limb muscle area and from blood. MVs were mainly released from endothelial cells (ECs) and induced Mo differentiation to endothelial cell-like (ECL) cells. Differentiation to ECL cells encompassed highly strict hierarchycal transcription factor activation, initiated by ETS1 activation. MVs secreted by microvascular ECs overexpressing TF (upTF-EMVs), were injected in the ischemic hind limb in parallel with control EMVs (from random siRNA-treated cells) or EMVs released by silenced TF endothelial cells (siTF-EMVs). In animals treated with upTF-EMVs in the ischemic zone there was a highly significant increase in functional new vessels formation (seen by magnetic resonance angiography), a concomitant increase in the pool of circulating Ly6Clow Mo expressing vascular endothelial cell markers, and a significantly higher number of Mo/Macrophages surrounding and integrating the newly formed collaterals.

CONCLUSION

Ischemia-activated ECs release EMVs rich in TF that induce monocyte differentiation into ECL cells and the formation of new vessels in the ischemic zone. TF by this mechanism of formation of new blood microvessels can contribute to ischemic tissue repair.

TRANSLATIONAL PERSPECTIVE

Neovascularization is the cornerstone of limb preservation in peripheral artery disease. Neovessel formation occurring during postnatal development is usually connected with inflammation. Advanced studies in the field of vascular biology have reported that monocytes can acquire endothelial features under angiogenic stimulation. We report that after ischemia affected endothelial cells release microvesicles rich in tissue factor that act as endogenous triggers by interacting with monocytes in an autocrine fashion, coaxing the cells to differentiate into functional endothelial cells. These differentiated cells have the ability to increase blood flow into ischemic tissue. The present study depicts a new concept in the mechanisms governing vessel formation in ischemic tissue.

Adverse Effect of Circadian Rhythm Disorder on Reparative Angiogenesis in Hind Limb Ischemia

Background Circadian rhythm disorders, often seen in modern lifestyles, are a major social health concern. The aim of this study was to examine whether circadian rhythm disorders would influence angiogenesis and blood perfusion recovery in a mouse model of hind limb ischemia. Methods and Results A jet-lag model was established in C57BL/6J mice using a light-controlled isolation box. Control mice were kept at a light/dark 12:12 (12-hour light and 12-hour dark) condition. Concentrations of plasma vascular endothelial growth factor and circulating endothelial progenitor cells in control mice formed a circadian rhythm, which was diminished in the jet-lag model (P<0.05). The jet-lag condition deteriorated tissue capillary formation (P<0.001) and tissue blood perfusion recovery (P<0.01) in hind limb ischemia, which was associated with downregulation of vascular endothelial growth factor expression in local ischemic tissue and in the plasma. Although the expression of clock genes (ie, Clock, Bmal1, and Cry) in local tissues was upregulated after ischemic injury, the expression levels of cryptochrome (Cry) 1 and Cry2 were inhibited by the jet-lag condition. Next, Cry1 and Cry2 double-knockout mice were examined for blood perfusion recoveries and a reparative angiogenesis. Cry1 and Cry2 double-knockout mice revealed suppressed capillary density (P<0.001) and suppressed tissue blood perfusion recovery (P<0.05) in the hind limb ischemia model. Moreover, knockdown of CRY1/2 in human umbilical vein endothelial cells was accompanied by increased expression of WEE1 and decreased expression of HOXC5. This was associated with decreased proliferative capacity, migration ability, and tube formation ability of human umbilical vein endothelial cells, respectively, leading to impairment of angiogenesis. Conclusions Our data suggest that circadian rhythm disorder deteriorates reparative ischemia-induced angiogenesis and that maintenance of circadian rhythm plays an important role in angiogenesis.

Deciphering the in vivo Dynamic Proteomics of Mesenchymal Stem Cells in Critical Limb Ischemia

Objective

Regenerative therapy using mesenchymal stem cells (MSC) is a promising therapeutic method for critical limb ischemia (CLI). To understand how the cells are involved in the regenerative process of limb ischemia locally, we proposed a metabolic protein labeling method to label cell proteomes in situ and then decipher the proteome dynamics of MSCs in ischemic hind limb.

Methods and Results

In this study, we overexpressed mutant methionyl-tRNA synthetase (MetRS), which could utilize azidonorleucine (ANL) instead of methionine (Met) during protein synthesis in MSCs. Fluorescent non-canonical amino-acid tagging (FUNCAT) was performed to detect the utilization of ANL in mutant MSCs. Mice with hindlimb ischemia (HLI) or Sham surgery were treated with MetRS^mut MSCs or PBS, followed by i.p. administration of ANL at days 0, 2 6, and 13 after surgery. FUNCAT was also performed in hindlimb tissue sections to demonstrate the incorporation of ANL in transplanted cells in situ. At days 1, 3, 7, and 14 after the surgery, laser doppler imaging were performed to detect the blood reperfusion of ischemic limbs. Ischemic tissues were also collected at these four time points for histological analysis including HE staining and vessel staining, and processed for click reaction based protein enrichment followed by mass spectrometry and bioinformatics analysis. The MetRS^mut MSCs showed strong green signal in cell culture and in HLI muscles as well, indicating efficient incorporation of ANL in nascent protein synthesis. By 14 days post-treatment, MSCs significantly increased blood reperfusion and vessel density, while reducing inflammation in HLI model compared to PBS. Proteins enriched by click reaction were distinctive in the HLI group vs. the Sham group. 34, 31, 49, and 26 proteins were significantly up-regulated whereas 28, 32, 62, and 27 proteins were significantly down-regulated in HLI vs. Sham at days 1, 3, 7, and 14, respectively. The differentially expressed proteins were more pronounced in the pathways of apoptosis and energy metabolism.

Conclusion

In conclusion, mutant MetRS allows efficient and specific identification of dynamic cell proteomics in situ, which reflect the functions and adaptive changes of MSCs that may be leveraged to understand and improve stem cell therapy in critical limb ischemia.

β 3 Adrenergic Receptor Stimulation Promotes Reperfusion in Ischemic Limbs in a Murine Diabetic Model

Aims/Hypothesis: Peripheral arterial disease (PAD) is a major burden, resulting in limb claudication, repeated surgical interventions and amputation. There is an unmet need for improved medical management of PAD that improves quality of life, maintains activities of daily life and reduces complications. Nitric oxide (NO)/redox balance is a key regulator of angiogenesis. We have previously shown beneficial effects of a β₃ adrenergic receptor (β₃AR) agonist on NO/redox balance. We hypothesized that β₃AR stimulation would have therapeutic potential in PAD by promoting limb angiogenesis.

Methods: The effect of the β₃AR agonist CL 316,243 (1–1,000 nmol/L in vitro, 1 mg/kg/day s. c) was tested in established angiogenesis assays with human endothelial cells and patient-derived endothelial colony forming cells. Post-ischemia reperfusion was determined in streptozotocin and/or high fat diet-induced diabetic and non-diabetic mice in vivo using the hind limb ischemia model.

Results: CL 316,243 caused accelerated recovery from hind limb ischemia in non-diabetic and type 1 and 2 diabetic mice. Increased eNOS activity and decreased superoxide generation were detected in hind limb ischemia calf muscle from CL 316, 243 treated mice vs. controls. The protective effect of CL 316,243 in diabetic mice was associated with >50% decreases in eNOS glutathionylation and nitrotyrosine levels. The β₃AR agonist directly promoted angiogenesis in endothelial cells in vitro. These pro-angiogenic effects were β₃AR and NOS-dependent.

Conclusion/Interpretation:β₃AR stimulation increased angiogenesis in diabetic ischemic limbs, with demonstrable improvements in NO/redox balance and angiogenesis elicited by a selective agonist. The orally available β₃AR agonist, Mirabegron, used for overactive bladder syndrome, makes translation to a clinical trial by repurposing of a β₃AR agonist to target PAD immediately feasible.

Therapeutic angiogenesis using zinc oxide nanoflowers for the treatment of hind limb ischemia in rat model

Critical limb ischemia (CLI) is considered as a severe type of peripheral artery diseases (PADs) which occurs due to the inadequate supply of blood to the limb extremities. CLI patients often suffer from extreme cramping pain, impaired wound healing, immobility, cardiovascular complications, amputation of the affected limb and even death. The conventional therapy for the treatment of CLI includes surgical revascularization as well as restoring angiogenesis using growth factor therapy. However, surgical revascularization is suitable for only a minor percentage of CLI patients and it is associated with high perioperative mortality rate. The use of growth factors is also limited in terms of their poor therapeutic angiogenesis potential as observed by the earlier clinical studies, which could be attributed to their poor bio-availability and non-specificity issues. Therefore, to outweigh the aforesaid disadvantages of the conventional strategies, there is an utmost need for the advancement of new alternative therapeutic biomaterials to treat CLI. Since past few decades, various research groups including ours have been involved in developing different pro-angiogenic nanomaterials. Among them, zinc oxide nanoflowers (ZONF), established in our laboratory, are considered as one of the potent nanoparticles to induce therapeutic angiogenesis. In our earlier studies, we have depicted that ZONF promote angiogenesis by inducing the formation of reactive oxygen species (ROS) and nitric oxide (NO) as well as activating Akt/MAPK/eNOS cell signaling pathways in the endothelial cells. Recently, we have also reported the therapeutic potential of ZONF to treat cerebral ischemia through their neuritogenic and neuroprotective properties, exploiting angio-neural cross talk. Considering the excellent pro-angiogenic properties of ZONF and importance of revascularization for the recovery of CLI, in this present study, we have comprehensively explored the therapeutic potential of ZONF in a rat hind limb ischemia model (established by ligating the femoral artery of hind limb), an animal model that mimics CLI in humans. The behavioural studies, laser Doppler perfusion imaging, histopathology, immunofluorescence as well as estimation of serum NO level depicted that the administration of ZONF could ameliorate the ischemic conditions in rats at a faster rate by promoting therapeutic angiogenesis to the ischemic sites. Altogether, the present study offers an alternative nanomedicine approach employing ZONF for the treatment of PADs.

BMP Receptor Inhibition Enhances Tissue Repair in Endoglin Heterozygous Mice

Hereditary hemorrhagic telangiectasia type 1 (HHT1) is a severe vascular disorder caused by mutations in the TGFβ/BMP co-receptor endoglin. Endoglin haploinsufficiency results in vascular malformations and impaired neoangiogenesis. Furthermore, HHT1 patients display an impaired immune response. To date it is not fully understood how endoglin haploinsufficient immune cells contribute to HHT1 pathology. Therefore, we investigated the immune response during tissue repair in Eng+/- mice, a model for HHT1. Eng+/- mice exhibited prolonged infiltration of macrophages after experimentally induced myocardial infarction. Moreover, there was an increased number of inflammatory M1-like macrophages (Ly6Chigh/CD206-) at the expense of reparative M2-like macrophages (Ly6Clow/CD206+). Interestingly, HHT1 patients also showed an increased number of inflammatory macrophages. In vitro analysis revealed that TGFβ-induced differentiation of Eng+/- monocytes into M2-like macrophages was blunted. Inhibiting BMP signaling by treating monocytes with LDN-193189 normalized their differentiation. Finally, LDN treatment improved heart function after MI and enhanced vascularization in both wild type and Eng+/- mice. The beneficial effect of LDN was also observed in the hind limb ischemia model. While blood flow recovery was hampered in vehicle-treated animals, LDN treatment improved tissue perfusion recovery in Eng+/- mice. In conclusion, BMPR kinase inhibition restored HHT1 macrophage imbalance in vitro and improved tissue repair after ischemic injury in Eng+/- mice.

MicroRNA-139-5p upregulation is associated with diabetic endothelial cell dysfunction by targeting c-jun

Dysfunction of endothelial cells (ECs) and their progenitor cells is an important feature of diabetic vascular disease. MicroRNA (miR)-139-5p is involved in inhibiting the metastasis and progression of diverse malignancies. However, the role of miR-139-5p in ECs still remains unclarified. Here we demonstrated that miR-139-5p expression was elevated in endothelial colony-forming cells (ECFCs) isolated from patients with diabetes, ECs derived from the aorta of diabetic rodents, and human umbilical vein endothelial cells (HUVECs) cultured in high glucose media. MiR-139-5p mimics inhibited tube formation, migration, proliferation, and down-regulated expression of c-jun, vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF)-B, in ECFCs and HUVECs, respectively; moreover, miR-139-5p inhibitors reversed the tendency. Further, gain- and-loss function experiments and ChIP assay indicated that miR-139-5p regulate functions of ECFCs by targeting c-jun-VEGF/PDGF-B pathway. In vivo experiments (Matrigel plug assay and hindlimb ischemia model) showed that miR-139-5p downregulation further promoted ECFC-mediated angiogenesis and blood perfusion. In conclusion, diabetes-mediated high miR-139-5p expression inhibits the c-jun-VEGF/PDGF-B pathway, thus decreasing ECFCs migration, tube formation and proliferation, which subsequently reduces ECs survival. Therefore, miR-139-5p might be an important therapeutic target in the treatment of diabetic vasculopathy in the future.

SIRT5 deficiency enhances the proliferative and therapeutic capacities of adipose-derived mesenchymal stem cells via metabolic switching

BACKGROUND

Mesenchymal stem cells (MSCs) have therapeutic potential for multiple ischemic diseases. However, in vitro expansion of MSCs before clinical application leads to metabolic reprogramming from glycolysis to oxidative phosphorylation, drastically impairing their proliferative and therapeutic capacities. This study aimed to define the regulatory effects of Sirtuin 5 (SIRT5) on the proliferative and therapeutic functions of adipose-derived MSCs (ADMSCs) during in vitro expansion.

METHODS

ADMSCs were isolated from wild-type (WT) and Sirt5-knockout (Sirt5-/- ) mice. Cell counting assay was used to investigate the proliferative capacities of the ADMSCs. Dihydroethidium and senescence-associated β-galactosidase stainings were used to measure intracellular ROS and senescence levels. Mass spectrometry was used to analyze protein succinylation. Oxygen consumption rates and extra cellular acidification rates were measured as indicators of mitochondrial respiration and glycolysis. Metabolic-related genes expression were verified by quantitative PCR and western blot. Hind limb ischemia mouse model was used to evaluate the therapeutic potentials of WT and Sirt5-/- ADSMCs.

RESULTS

SIRT5 protein levels were upregulated in ADMCs during in vitro expansion. Sirt5-/- ADMSCs exhibited a higher proliferation rate, delayed senescence, and reduced ROS accumulation. Furthermore, elevated protein succinylation levels were observed in Sirt5-/- ADMSCs, leading to the reduced activity of tricarboxylic acid cycle-related enzymes and attenuated mitochondrial respiration. Glucose uptake, glycolysis, and pentose phosphate pathway were elevated in Sirt5-/- ADMSCs. Inhibition of succinylation by glycine or re-expression of Sirt5 reversed the metabolic alterations in Sirt5-/- ADMSCs, thus abolishing their enhanced proliferative capacities. In the hind limb ischemia mouse model, SIRT5-/- ADMSCs transplantation enhanced blood flow recovery and angiogenesis compared with WT ADMSCs.

CONCLUSIONS

Our results indicate that SIRT5 deficiency during ADMSC culture expansion leads to reversed metabolic pattern, enhanced proliferative capacities, and improved therapeutic outcomes. These data suggest SIRT5 as a potential target to enhance the functional properties of MSCs for clinical application.

All-in-One Hydrogel Realizing Adipose-Derived Stem Cell Spheroid Production and In Vivo Injection via "Gel-Sol" Transition for Angiogenesis in Hind Limb Ischemia

Adipose-derived stem cell (ASC) spheroids exhibit enhanced angiogenic efficacy toward ischemia treatment. Thus, it is necessary to develop an all-in-one platform that enables efficient spheroid production, collection, and injectable implantation in vivo. The present study fabricated a poly(l-glutamic acid) (PLGA)-based porous hydrogel that can not only produce ASC spheroids but also conveniently collect spheroids for in vivo implantation via minimally invasive injection to treat hind limb ischemia. PLGA was cross-linked with cystamine (Cys), which contains disulfide bonds, to form a porous hydrogel that could realize "gel-sol" transition by the reduction effect of glutathione (GSH). For one thing, it was found that the introduction of the disulfide bond in the PLGA hydrogel promoted cellular adhesion via combining fibronectin, preventing the formation of spheroids, while the introduction of polyethylene glycol monomethyl ether (mPEG) could disturb the effect of the disulfide bond on cellular adhesion, supporting spheroid formation inside the porous hydrogel. For another, the porous hydrogel transferred into a syringe could turn into liquid polymer solution within about 40 min for collection of the produced spheroids and in vivo injection. In addition, because of the lubrication of polymer solution, the spheroids were protected during the injection of the spheroids/polymer suspensoid through a 25G syringe needle, avoiding damages from shearing. After the in vivo injection, the enhanced paracrine secretion of ASC spheroids resulted in promoted angiogenesis and muscle regeneration, exhibiting obvious therapeutic effect on limb ischemia in mice after 21 days. At the same time, PLGA-based material exhibited well-performed biocompatibility in vivo.

Cytokine Profile in Experimental Models of Critical Limb Ischemia in Rats

We studied the effect of intramuscular administration of a cellular product (mesenchymal stem cells, conditioned media, and erythropoietin) on cytokine levels in blood serum, conditioned media of bone marrow mononuclears, and calf muscles in Wistar rats with hind limb ischemia. It is shown that the cellular product reduces the proinflammatory background at the early stages of the experiment and increases the content proangiogenic factors.

VEGF-A-Cleavage by FSAP and Inhibition of Neo-Vascularization

Alternative splicing leads to the secretion of multiple forms of vascular endothelial growth factor-A (VEGF-A) that differ in their activity profiles with respect to neovascularization. FSAP (factor VII activating protease) is the zymogen form of a plasma protease that is activated (FSAPa) upon tissue injury via the release of histones. The purpose of the study was to determine if FSAPa regulates VEGF-A activity in vitro and in vivo. FSAP bound to VEGF₁₆₅, but not VEGF₁₂₁, and VEGF₁₆₅ was cleaved in its neuropilin/proteoglycan binding domain. VEGF₁₆₅ cleavage did not alter its binding to VEGF receptors but diminished its binding to neuropilin. The stimulatory effects of VEGF₁₆₅ on endothelial cell proliferation, migration, and signal transduction were not altered by FSAP. Similarly, proliferation of VEGF receptor-expressing BAF3 cells, in response to VEGF₁₆₅, was not modulated by FSAP. In the mouse matrigel model of angiogenesis, FSAP decreased the ability of VEGF₁₆₅, basic fibroblast growth factor (bFGF), and their combination, to induce neovascularization. Lack of endogenous FSAP in mice did not influence neovascularization. Thus, FSAP inhibited VEGF₁₆₅-mediated angiogenesis in the matrigel model in vivo, where VEGF’s interaction with the matrix and its diffusion are important.

Variations in Surgical Procedures for Inducing Hind Limb Ischemia in Mice and the Impact of These Variations on Neovascularization Assessment

Mouse hind limb ischemia is the most common used preclinical model for peripheral arterial disease and critical limb ischemia. This model is used to investigate the mechanisms of neovascularization and to develop new therapeutic agents. The literature shows many variations in the model, including the method of occlusion, the number of occlusions, and the position at which the occlusions are made to induce hind limb ischemia. Furthermore, predefined end points and the histopathological and radiological analysis vary. These differences hamper the correlation of results between different studies. In this review, variations in surgical methods of inducing hind limb ischemia in mice are described, and the consequences of these variations on perfusion restoration and vascular remodeling are discussed. This study aims at providing the reader with a comprehensive overview of the methods so far described, and proposing uniformity in research of hind limb ischemia in a mouse model.

Carnosine Supplementation Enhances Post Ischemic Hind Limb Revascularization

High (millimolar) concentrations of the histidine containing dipeptide - carnosine (β-alanine-L-histidine) are present in the skeletal muscle. The dipeptide has been shown to buffer intracellular pH, chelate transition metals, and scavenge lipid peroxidation products; however, its role in protecting against tissue injury remains unclear. In this study, we tested the hypothesis that carnosine protects against post ischemia by augmenting HIF-1α angiogenic signaling by Fe2+ chelation. We found that wild type (WT) C57BL/6 mice, subjected to hind limb ischemia (HLI) and supplemented with carnosine (1g/L) in drinking water, had improved blood flow recovery and limb function, enhanced revascularization and regeneration of myocytes compared with HLI mice placed on water alone. Carnosine supplementation enhanced the bioavailability of carnosine in the ischemic limb, which was accompanied by increased expression of proton-coupled oligopeptide transporters. Consistent with our hypothesis, carnosine supplementation augmented HIF-1α and VEGF expression in the ischemic limb and the mobilization of proangiogenic Flk-1+/Sca-1+ cells into circulation. Pretreatment of murine myoblast (C2C12) cells with octyl-D-carnosine or carnosine enhanced HIF-1α protein expression, VEGF mRNA levels and VEGF release under hypoxic conditions. Similarly pretreatment of WT C57/Bl6 mice with carnosine showed enhanced blood flow in the ischemic limb following HLI surgery. In contrast, pretreatment of hypoxic C2C12 cells with methylcarcinine, a carnosine analog, lacking Fe2+ chelating capacity, had no effect on HIF-1α levels and VEGF release. Collectively, these data suggest that carnosine promotes post ischemic revascularization via augmentation of pro-angiogenic HIF-1α/VEGF signaling, possibly by Fe2+ chelation.

Transplantation of Adipose Stromal Cell Sheet Producing Hepatocyte Growth Factor Induces Pleiotropic Effect in Ischemic Skeletal Muscle

Cell therapy remains a promising approach for the treatment of cardiovascular diseases. In this regard, the contemporary trend is the development of methods to overcome low cell viability and enhance their regenerative potential. In the present study, we evaluated the therapeutic potential of gene-modified adipose-derived stromal cells (ADSC) that overexpress hepatocyte growth factor (HGF) in a mice hind limb ischemia model. Angiogenic and neuroprotective effects were assessed following ADSC transplantation in suspension or in the form of cell sheet. We found superior blood flow restoration, tissue vascularization and innervation, and fibrosis reduction after transplantation of HGF-producing ADSC sheet compared to other groups. We suggest that the observed effects are determined by pleiotropic effects of HGF, along with the multifactorial paracrine action of ADSC which remain viable and functionally active within the engineered cell construct. Thus, we demonstrated the high therapeutic potential of the utilized approach for skeletal muscle recovery after ischemic damage associated with complex tissue degenerative effects.

The Neuropeptide Secretoneurin Exerts a Direct Effect on Arteriogenesis In Vivo and In Vitro

It is well known that nerves modulate the development and remodeling of blood vessels by releasing different neuropeptides and neurotransmitters. Secretoneurin (SN), a neuropeptide located in nerve fibers along blood vessels, acts as a pro-angiogenic agent and induces postnatal vasculogenesis. However, little is known about its involvement in arteriogenesis. In the present study, we tested the hypothesis that SN promotes arteriogenesis in a rat model of hind limb ischemia, as such, we evaluated the effect of this neuropeptide on proliferation and the production of adhesion and chemotaxis molecules in vascular smooth muscle cells (VSMCs), the main component that carries the burden of the transformation of a small arteriole into a large collateral vessel. In vivo, SN-immunoreactive nerve fibers were abundantly distributed in the adventitia of the collateral vessel. Moreover, administration of SN induced cell proliferation in the vascular wall and the infiltration of inflammatory cells/macrophages to promote collateral vessel growth. This was shown by an increased density of arterioles/arteries, together with a well-developed network of collateral vessels, and well-preserved skeletal muscles. In vitro, SN exerted proliferative effects on VSMCs and stimulated these cells to express adhesion molecules. In conclusion, our data demonstrate for the first time that SN acts as a mediator of inflammation, contributing to collateral vessel growth, in addition to directly stimulating cell proliferation in the vascular wall to promote collateral vessel growth in a rat model of hind limb ischemia. Anat Rec, 301:1917-1927, 2018. © 2018 Wiley Periodicals, Inc.

[Acupoint injection of BMSCs combined with Chinese herbs for capillary density in ischemic hind limb of diabetes mellitus rats]

OBJECTIVE

To observe the effect of acupoint injection of bone mesenchymal stem cells (BMSCs) combined with Chinese herbs of benefiting qi for activating blood circulation for capillary density and arterioles density in skeletal muscle in ischemic hind limb of diabetes mellitus (DM) rats.

METHODS

A total of 80 rats were randomized into a normal sham operation group (10 rats) and a model group (70 rats). Disposable intraperitoneal injection of streptozotocin (STZ, 50.0 mg/kg) was used to establish DM model, and the rats in the model group were randomized into 7 subgroups, 10 rats in each one. The subgroups were the DM sham operation group, DM ischemic group, Chinese herb group (intragastric herbs of benefiting qi for activating blood circulation), local injection group (BMSCs local injection), local injection + Chinese herb group (BMSCs local injection combined with intragastric herbs of benefiting qi for activating blood circulation), acupoint injection group (BMSCs acupoint injection), acupoint injection + Chinese herb group (BMSCs acupoint injection combined with intragastric herbs of benefiting qi for activating blood circulation). The local injection was phosphate buffer (PBS) injection at the equidistant 5 points along the line between the ischemic tissue and the normal tissue a time. The acupoints were "Sanyinjiao" (SP 6), "Zhaohai" (KI 6), "Huantiao" (GB 30), "Housanli" (ST 36) and "Yanglingquan" (GB 34). 100 μL BMSCs with 1×10⁷/mL was totally injected at the above acupoints for one rat, 20 μL an acupoint. 1.5 kg/L Chinese herbs were applied by intragastric administration, including 120 g Radix Astragali, 120 g Codonopsis, 48 g Radix Glycyrrhiza, 120 g Angelica sinensis, 120 g Blood Rattan, 48 g Achyranthes bidentata. Intragastric distilled water was used in the other non-Chinese herb groups. The expressions of α-smooth muscle actin (α-actin), latelet endothelial cell adhesion molecule (CD31) and von willebrand factor (vWF) in the skeletal muscle were detected with immunohistochemical SP two-step method.

RESULTS

Twenty-one days after intervention, the expressions of α-actin and CD31 on the operation hind limb were higher than those on the healthy hind limb in all the groups, except the Chinese herb group (P<0.05，P<0.01). The vWF expressions on the operation side were lower than those on the healthy side in the Chinese herb group, the local injection group, the local injection + Chinese herb group and the acupoint injection + Chinese herb group (P<0.05, P<0.01). The α-actin expression on the operation side in the acupoint injection + Chinese herb group was higher than those in the normal sham operation group, DM sham operation group, the DM ischemic group and the local injection group (P<0.05, P<0.01). The CD31 expressions in the acupoint injection group, the acupoint injection + Chinese herb group, local injection + Chinese herb group were higher than those in the normal sham operation group, DM sham operation group and DM ischemic group (P<0.05, P<0.01). The CD31 expression in the acupoint injection + Chinese herb group was higher than those in the Chinese herb group and the local injection group (both P<0.05). The vWF expressions in the local injection + Chinese herb group, the acupoint injection group and the acupoint injection + Chinese herb group lower than those in the DM sham operation group and the DM ischemic group (P<0.05, P<0.01).

CONCLUSION

schemia increases the expressions of the vascular density related factors of α-actin and CD31. It is more obvious for the increasing expressions of α-actin and CD31, and decreasing expression of vWF with the interventions of simple BMSCs injection and simple Chinese herbs of benefiting qi for activating blood circulation, especially with the combination of the above tow methods. It is indicated that acupoint injection of BMSCs combined with Chinese herbs of benefiting qi for activating blood circulation can improve the angiogenesis of ischemic tissue.

Role of genetics in peripheral arterial disease outcomes; significance of limb-salvage quantitative locus-1 genes

Peripheral artery disease is a major health care problem with significant morbidity and mortality. Humans with peripheral artery disease exhibit two major and differential clinical manifestations - intermittent claudication and critical limb ischemia. Individuals with intermittent claudication or critical limb ischemia have overlapping risk factors and objective measures of blood flow. Hence, we hypothesized that variation in genetic make-up may be an important determinant in the severity of peripheral artery disease. Previous studies have identified polymorphism in genes, contributing to extent of atherosclerosis but much less is known about polymorphisms associated with genes that can influence peripheral artery disease severity. This review outlines some of the progress made up-to-date to unravel the molecular mechanisms underlining differential peripheral artery disease severity. By exploring the recovery phenotype of different mouse strains following experimental peripheral artery disease, our group identified the limb salvage-associated quantitative trait locus 1 on mouse chromosome 7 as the first genetic modifier of perfusion recovery and tissue necrosis phenotypes. Furthermore, a number of genes within LSq-1, such as ADAM12, IL-21Rα, and BAG3 were identified as genetic modifiers of peripheral artery disease severity that function through preservation of endothelial and skeletal muscle cells during ischemia. Taken together, these studies suggest manipulation of limb salvage-associated quantitative trait locus 1 genes show great promise as therapeutic targets in the management of peripheral artery disease. Impact statement Peripheral artery disease (PAD) is a major health care problem with significant morbidity and mortality. Individuals with similar atherosclerosis burden do display different severity of disease. This review outlines some of the progress made up-to-date in unraveling the molecular mechanisms underlining differential PAD severity with a focus on the role of the Limb Salvage-associated Quantitative trait locus 1 (LSq-1), a key locus in adaptation to ischemia in PAD.

Inhalation of Fine Particulate Matter Impairs Endothelial Progenitor Cell Function Via Pulmonary Oxidative Stress

OBJECTIVE

Exposure to fine particulate matter (PM_2.5) air pollution is associated with the depletion of circulating endothelial progenitor cells (EPCs), as well as vascular injury and dysfunction. Nevertheless, it remains unclear whether PM_2.5 exposure leads to significant impairments in EPC function. Hence, we studied the effects of PM_2.5 on EPC-mediated recovery of vascular perfusion after hindlimb ischemia and examined the mechanisms whereby PM_2.5 exposure affects EPC abundance and function.

APPROACH AND RESULTS

In comparison with EPCs isolated from mice breathing filtered air, EPCs from mice exposed for 9 consecutive days (6 hours per day) to concentrated ambient PM_2.5 (CAP) had defects in both proliferation and tube formation. However, CAP exposure of mice overexpressing extracellular superoxide dismutase (ecSOD-Tg) in the lungs did not affect EPC tube formation. Exposure to CAP also suppressed circulating EPC levels, VEGF (vascular endothelial growth factor)-stimulated aortic Akt phosphorylation, and plasma NO levels in wild-type but not in ecSOD-Tg mice. EPCs from CAP-exposed wild-type mice failed to augment basal recovery of hindlimb perfusion when injected into unexposed mice subjected to hindlimb ischemia; however, these deficits in recovery of hindlimb perfusion were absent when using EPCs derived from CAP-exposed ecSOD-Tg mice. The improved reparative function of EPCs from CAP-exposed ecSOD-Tg mice was also reflected by greater expression of Mmp-9 and Nos3 when compared with EPCs from CAP-exposed wild-type mice.

CONCLUSIONS

Exposure to PM_2.5 impairs EPC abundance and function and prevents EPC-mediated vascular recovery after hindlimb ischemia. This defect is attributed, in part, to pulmonary oxidative stress and was associated with vascular VEGF resistance and a decrement in NO bioavailability.

Placenta-derived PLX-PAD mesenchymal-like stromal cells are efficacious in rescuing blood flow in hind limb ischemia mouse model by a dose- and site-dependent mechanism of action

BACKGROUND

In peripheral artery disease (PAD), blockage of the blood supply to the limbs, most frequently the legs, leads to impaired blood flow and tissue ischemia. Pluristem's PLX-PAD cells are placenta-derived mesenchymal stromal-like cells currently in clinical trials for the treatment of peripheral artery diseases.

METHODS

In this work, the hind limb ischemia (HLI) mouse model was utilized to study the efficacy and mechanism of action of PLX-PAD cells. ELISA assays were performed to characterize and quantitate PLX-PAD secretions in vitro.

RESULTS

PLX-PAD cells administered intramuscularly rescued blood flow to the lower limb after HLI induction in a dose-dependent manner. While rescue of blood flow was site-dependent, numerous administration regimes enabled rescue of blood flow, indicating a systemic effect mediated by PLX-PAD secretions. Live PLX-PAD cells were more efficacious than cell lysate in rescuing blood flow, indicating the importance of prolonged cytokine secretion for maximal blood flow recovery. In vitro studies showed a multifactorial secretion profile including numerous pro-angiogenic proteins; these are likely involved in the PLX-PAD mechanism of action.

DISCUSSION

Live PLX-PAD cells were efficacious in rescuing blood flow after the induction of HLI in the mouse model in a dose- and site-dependent manner. The fact that various administration routes of PLX-PAD rescued blood flow indicates that the mechanism of action likely involves one of systemic secretions which promote angiogenesis. Taken together, the data support the further clinical testing of PLX-PAD cells for PAD indications.

Co-injection of mesenchymal stem cells with endothelial progenitor cells accelerates muscle recovery in hind limb ischemia through an endoglin-dependent mechanism

Endothelial colony-forming cells (ECFCs) are progenitor cells committed to endothelial lineages and have robust vasculogenic properties. Mesenchymal stem cells (MSCs) have been described to support ECFC-mediated angiogenic processes in various matrices. However, MSC-ECFC interactions in hind limb ischemia (HLI) are largely unknown. Here we examined whether co-administration of ECFCs and MSCs bolsters vasculogenic activity in nude mice with HLI. In addition, as we have previously shown that endoglin is a key adhesion molecule, we evaluated its involvement in ECFC/MSC interaction. Foot perfusion increased on day 7 after ECFC injection and was even better at 14 days. Co-administration of MSCs significantly increased vessel density and foot perfusion on day 7 but the differences were no longer significant at day 14. Analysis of mouse and human CD31, and in situ hybridization of the human ALU sequence, showed enhanced capillary density in ECFC+MSC mice. When ECFCs were silenced for endoglin, coinjection with MSCs led to lower vessel density and foot perfusion at both 7 and 14 days (p<0.001). Endoglin silencing in ECFCs did not affect MSC differentiation into perivascular cells or other mesenchymal lineages. Endoglin silencing markedly inhibited ECFC adhesion to MSCs. Thus, MSCs, when combined with ECFCs, accelerate muscle recovery in a mouse model of hind limb ischemia, through an endoglin-dependent mechanism.

Neuropeptide Y3-36 incorporated into PVAX nanoparticle improves functional blood flow in a murine model of hind limb ischemia

We generated a novel nanoparticle called PVAX, which has intrinsic antiapoptotic and anti-inflammatory properties. This nanoparticle was loaded with neuropeptide Y_3-36 (NPY_3-36), an angiogenic neurohormone that plays a central role in angiogenesis. Subsequently, we investigated whether PVAX-NPY_3-36 could act as a therapeutic agent and induce angiogenesis and vascular remodeling in a murine model of hind limb ischemia. Adult C57BL/J6 mice (n = 40) were assigned to treatment groups: control, ischemia PBS, ischemia PVAX, ischemia NPY_3-36, and Ischemia PVAX-NPY_3-36 Ischemia was induced by ligation of the femoral artery in all groups except control and given relevant treatments (PBS, PVAX, NPY_3-36, and PVAX-NPY_3-36). Blood flow was quantified using laser Doppler imaging. On days 3 and 14 posttreatment, mice were euthanized to harvest gastrocnemius muscle for immunohistochemistry and immunoblotting. Blood flow was significantly improved in the PVAX-NPY_3-36 group after 14 days. Western blot showed an increase in angiogenic factors VEGF-R2 and PDGF-β (P = 0.0035 and P = 0.031, respectively) and antiapoptotic marker Bcl-2 in the PVAX-NPY_3-36 group compared with ischemia PBS group (P = 0.023). Proapoptotic marker Smad5 was significantly decreased in the PVAX-NPY_3-36 group as compared with the ischemia PBS group (P = 0.028). Furthermore, Y₂ receptors were visualized in endothelial cells of newly formed arteries in the PVAX-NPY_3-36 group. In conclusion, we were able to show that PVAX-NPY_3-36 can induce angiogenesis and arteriogenesis as well as improve functional blood flow in a murine model of hind limb ischemia.NEW & NOTEWORTHY Our research project proposes a novel method for drug delivery. Our patented PVAX nanoparticle can detect areas of ischemia and oxidative stress. Although there have been studies about delivering angiogenic molecules to areas of ischemic injury, there are drawbacks of nonspecific delivery as well as short half-lives. Our study is unique because it can specifically deliver NPY_3-36 to ischemic tissue and appears to extend the amount of time therapy is available, despite NPY_3-36's short half-life.

Dynamic imaging of allogeneic adipose-derived regenerative cells transplanted in ischemic hind limb of apolipoprotein E mouse model

Background

Transplantation of allogeneic adipose-derived regenerative cells (ADRCs) is a promising treatment modality for severe ischemic diseases. However, minimal information is available on the in vivo effects, fate, and migration of ADRCs, as well as the mechanisms of their therapeutic angiogenesis.

Materials and methods

In this study, green fluorescent protein-expressing ADRCs (GFP-ADRCs) were obtained, labeled with acetylated 3-aminopropyltrimethoxysilane (APTS)-coated iron oxide nanoparticles (APTS NPs), and injected into an old apolipoprotein E knockout (ApoE-KO) mouse model with hind limb ischemia. Then, 3.0 T magnetic resonance imaging (MRI) was performed to dynamically trace the role of ADRCs targeting hind limb ischemia in the ApoE-KO mice model.

Results

Labeled cells were visualized as large hypointense spots in ischemic muscles by serial 3.0 T MRI scans during a 4-week follow-up. The presence of labeled GFP-ADRCs was confirmed by Prussian blue staining and fluorescence microscopy on postmortem specimens.

Conclusion

This study showed that allogeneic ADRCs offer great potential application for therapeutic angiogenesis in severe ischemic disease based on the efficacy and feasibility of ADRC transplantation and on the available amounts of tissue.

Characterization of the Pall Celeris system as a point-of-care device for therapeutic angiogenesis

BACKGROUND AIMS

The Pall Celeris system is a filtration-based point-of-care device designed to obtain a high concentrate of peripheral blood total nucleated cells (PB-TNCs). We have characterized the Pall Celeris-derived TNCs for their in vitro and in vivo angiogenic potency.

METHODS

PB-TNCs isolated from healthy donors were characterized through the use of flow cytometry and functional assays, aiming to assess migratory capacity, ability to form capillary-like structures, endothelial trans-differentiation and paracrine factor secretion. In a hind limb ischemia mouse model, we evaluated perfusion immediately and 7 days after surgery, along with capillary, arteriole and regenerative fiber density and local bio-distribution.

RESULTS

Human PB-TNCs isolated by use of the Pall Celeris filtration system were shown to secrete a panel of angiogenic factors and migrate in response to vascular endothelial growth factor and stromal-derived factor-1 stimuli. Moreover, after injection in a mouse model of hind limb ischemia, PB-TNCs induced neovascularization by increasing capillary, arteriole and regenerative fiber numbers, with human cells detected in murine tissue up to 7 days after ischemia.

CONCLUSIONS

The Pall Celeris system may represent a novel, effective and reliable point-of-care device to obtain a PB-derived cell product with adequate potency for therapeutic angiogenesis.

Targeted molecular imaging of angiogenesis in PET and SPECT: a review

Over the past few decades, there have been significant advancements in the imaging techniques of positron emission tomography (PET) and single photon emission tomography (SPECT). These changes have allowed for the targeted imaging of cellular processes and the development of hybrid imaging systems (e.g., SPECT/CT and PET/CT), which provide both functional and structural images of biological systems. One area that has garnered particular attention is angiogenesis as it relates to ischemic heart disease and limb ischemia. Though the aforementioned techniques have benefits and consequences, they enable scientists and clinicians to identify regions that are vulnerable to or have been exposed to ischemic injury via non-invasive means. This literature review highlights the advancements in molecular imaging techniques and specific probes as they pertain to the process of angiogenesis in cardiovascular disease.

Peripheral arterial disease in diabetes: is there a role for genetics?

Atherosclerotic occlusion of vessels outside of the heart is commonly referred to as peripheral arterial disease (PAD). The lower extremity is the most common site of PAD and its development is associated with the same risk factors involved in general atherosclerosis. However, there is emerging evidence that other risk factors may play a key role in the development of PAD. Over the past decade polymorphism in a number of genes has been shown to contribute to the risk of developing PAD. These genes can be classified into proartherosclerosis or proatherothrombosis based on the known gene function. Moreover, they can be categorized as "novel" polymorphism when the function of the genes is not known or when the specific gene within an associated genetic locus is not known. It is intriguing that not only are gene polymorphisms associated with PAD being identified, but more recently studies are now finding gene polymorphisms that may be important in development of this syndrome only in the contest of certain environmental factors such as diabetes. Currently how these gene-environment interactions contribute to the pathogenesis of PAD is poorly understood but will likely play a critical role in future understanding of this complex disease.