Hemopexin reduces blood-brain barrier injury and protects synaptic plasticity in cerebral ischemic rats by promoting EPCs through the HO-1 pathway

Ischemic stroke causes endothelial dysfunction and blood-brain barrier dysfunction, thus damages synaptic plasticity such as learning and memory. In this study we aim to investigate the effect of hemopexin (HPX) in protecting synaptic plasticity and blood brain barrier integrity from toxic heme, and determine whether this effect is via the activation of endothelial progenitor cells (EPCs) through the heme oxygenase-1 (HO-1) pathway. Our data indicates HPX showed a significant effect in inducing the expression of HO-1, promoting the migration and differentiation of EPCs, facilitating new blood vessel formation thus protecting blood-brain barrier integrity. Also the magnitude of synaptic plasticity of rats recovered with HPX treatment. And in the presence of HO-1 blocker Zinc protoporphyrin-9 (ZnppIX), HPX lost its protective effect. This suggests that HPX protects endothelial and blood brain barrier integrity from toxic heme, thus protects neurologic function in cerebral ischemic rats in HO-1 pathway.

The promotion of tissue engineering blood vessel patency by CGS21680 through regulating pro-inflammatory activities of endothelial progenitor cell

The mobilization and homing of endothelial progenitor cells (EPCs) contribute to the rapid endothelialization of tissue engineering blood vessel (TEBV). Inflammation can affect TEBV patency, and monocytes/macrophages (MM) are the main effector cells. But it is not clear how EPCs interact with MM after TEBV transplantation. Our results showed acellular materials would not directly cause acute and severe inflammatory responses but activate E-selectin expression in homing EPCs, gradually promoting the polarization of MM to the M1. Adenosine A2a receptor agonist CGS21680 promoted the secretion of more proangiogenic factors from MM, inducing EPC migration and mobilization. CGS21680 could inhibit MM polarization to the M1 type through the down-regulation of EPC proinflammatory molecules, such as E-selectin. Chitosan/(2-hydroxypropyl)-β-cyclodextrin nanoparticles were prepared to control the release of CGS-21680 and then modified to TEBVs through layer-by-layer assembly. Animal experiments showed that this TEBV can maintain patency for 6 months and good endothelialization was observed. In summary, our results showed the regulation of EPC pro-inflammatory activities is a new approach to enhance TEBV patency. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2634-2642, 2018.

Comparison of Ticagrelor Versus Prasugrel for Inflammation, Vascular Function, and Circulating Endothelial Progenitor Cells in Diabetic Patients With Non-ST-Segment Elevation Acute Coronary Syndrome Requiring Coronary Stenting: A Prospective, Randomized, Crossover Trial

OBJECTIVES

This study compared adenosine-associated pleiotropic effects of the 2 P2Y₁₂ receptor antagonists on vascular function, systemic inflammation, and circulating endothelial progenitor cells (EPCs).

BACKGROUND

Both ticagrelor and prasugrel have potent antiplatelet effects. However, only ticagrelor inhibits cellular uptake of adenosine.

METHODS

Using a randomized, crossover design with 10-week follow-up ticagrelor or prasugrel was administered to type 2 diabetic patients with non-ST-segment elevation acute coronary syndrome requiring stent implantation. A total of 62 patients underwent randomization in a 1:1 ratio to receive ticagrelor or prasugrel for 5 weeks followed by a direct cross over to the alternative treatment for 5 additional weeks. Brachial artery flow-mediated dilation, inflammatory markers, and number of circulating EPCs were compared.

RESULTS

Improvement in brachial artery flow-mediated dilation was greater in the ticagrelor group (0.15 ± 0.19 mm vs. -0.03 ± 0.18 mm; p < 0.001). Moreover, ticagrelor compared with prasugrel decreased interleukin 6 (-0.58 ± 0.43 pg/ml vs. -0.05 ± 0.24 pg/ml; p < 0.001), tumor necrosis factor alpha (-5.62 ± 4.40 pg/ml vs. -0.42 ± 2.64 pg/ml; p < 0.001), and increased adiponectin (2.31 ± 2.00 μg/ml vs. 0.08 ± 1.50 μg/ml; p < 0.001) during 10-week follow-up. Other inflammatory cytokines like high-sensitivity C-reactive protein and soluble vascular cell adhesion molecule-1 were decreased in both groups. Ticagrelor compared with prasugrel significantly increased absolute numbers of circulating EPCs CD34+/KDR+ (42.5 ± 37.8 per μl vs. -28.2 ± 23.7 per μl; p < 0.001), CD34+/CD117+ (51.9 ± 77.2 per μl vs. -66.3 ± 45.2 per μl; p < 0.001), and CD34+/CD133+ (55.2 ± 69.2 per μl vs. -28.0 ± 34.1 per μl; p < 0.001).

CONCLUSIONS

Compared with prasugrel, ticagrelor significantly decreased inflammatory cytokines such as interleukin 6 and tumor necrosis factor alpha and increased circulating EPCs, contributing to improved arterial endothelial function in diabetic non-ST-segment elevation acute coronary syndrome patients. Thus, data support that pleiotropic effects of ticagrelor beyond its potent antiplatelet effects could contribute to additional clinical benefits. (Comparison of Ticagrelor vs. Prasugrel on Inflammation, Arterial Stiffness, Endothelial Function, and Circulating Endothelial Progenitor Cells in Diabetic Patients With Non-ST Elevation Acute Coronary Syndrome [NSTE-ACS] Requiring Coronary Stenting; NCT02487732).

The synergistic effects of saxagliptin and metformin on CD34+ endothelial progenitor cells in early type 2 diabetes patients: a randomized clinical trial

AIMS

Type 2 diabetes is associated with endothelial dysfunction leading to cardiovascular disease. CD34+ endothelial Progenitor Cells (EPCs) are responsible for endothelial repair and neo-angiogenesis and can be used as a cardiovascular disease risk biomarker. This study investigated whether the addition of saxagliptin, a DPP-IV inhibitor, to metformin, may reduce cardiovascular disease risk in addition to improving glycemic control in Type 2 diabetes patients.

METHODS

In 12 week, double-blind, randomized placebo-controlled trial, 42 subjects already taking metformin 1-2 grams/day were randomized to placebo or saxagliptin 5 mg. Subjects aged 40-70 years with diabetes for < 10 years, with no known cardiovascular disease, BMI 25-39.9, HbA1C 6-9% were included. We evaluated EPCs number, function, surface markers and gene expression, in addition to arterial stiffness, blood biochemistries, resting energy expenditure, and body composition parameters. A mixed model regression to examine saxagliptin vs placebo, accounting for within-subject autocorrelation, was done with SAS (p < 0.05).

RESULTS

Although there was no significant increase in CD34+ cell number, CD31+ cells percentage increased. Saxagliptin increased migration (in response to SDF1α) with a trend of higher colony formation count. MNCs cytometry showed higher percentage of CXCR4 double positivity for both CD34 and CD31 positive cells, indicating a functional improvement. Gene expression analysis showed an upregulation in CD34+ cells for antioxidant SOD1 (p < 0.05) and a downregulation in CD34- cells for IL-6 (p < 0.01). For arterial stiffness, both augmentation index and systolic blood pressure measures went down in saxagliptin subjects (p < 0.05).

CONCLUSION

Saxagliptin, in combination with metformin, can help improve endothelial dysfunction in early diabetes before macrovascular complications appear. Trial registration Trial is registered under clinicaltrials.gov, NCT02024477.

The Effect of Mineralocorticoid Receptor Antagonists on Recruitment and Function of Endothelial Progenitor Cells in Patients with Congestive Heart Failure

BACKGROUND

Circulating endothelial progenitor cells have an important role in the process of vascular repair. Impaired recruitment and function of endothelial progenitor cells is related to the pathophysiology of congestive heart failure. Endothelial progenitor cells have been shown to express the mineralocorticoid receptor.

OBJECTIVES

To investigate the effect of mineralocorticoid receptor antagonists on endothelial progenitor cells in patients with heart failure.

METHODS

Twenty-four patients with compensated heart failure, who were not under mineralocorticoid receptor antagonist therapy, were recruited. Either eplerenone (n=8) or spironolactone (n=16) therapy was initiated. Circulating endothelial progenitor cell level, identified as the proportion of mononuclear cells expressing vascular endothelial growth factor receptor 2 (VEGFR-2), CD133, and CD34, was evaluated by flow cytometry at baseline and after 8 weeks. Following 7 days of culture, colonies were counted by microscopy and MTT assay was performed on randomly selected patients (n=12) to estimate viability.

RESULTS

Both median CD34+/VEGFR2+ and median CD133+/VEGFR2+ increased significantly (P = 0.04 and 0.02, respectively). However, the number of colonies and viability of the cells after therapy (as assessed by the MTT assay) was not significantly different compared with the baseline.

CONCLUSIONS

These preliminary results suggest that mineralocorticoid receptor blockade may enhance endothelial progenitor cells recruitment in patients with compensated heart failure.

Methylglyoxal induced advanced glycation end products (AGE)/receptor for AGE (RAGE)-mediated angiogenic impairment in bone marrow-derived endothelial progenitor cells

Endothelial cells (ECs) maintain the structure and function of blood vessels and are readily exposed to exogenous and endogenous toxic substances in the circulatory system. Bone marrow-derived endothelial progenitor cells (EPCs) circulate in the blood and differentiate to EC, which are known to participate in angiogenesis and regeneration of injured vessels. Dysfunction in EPC contributes to cardiovascular complications in patients with diabetes, but the precise molecular mechanisms underlying diabetic EPC abnormalities are not completely understood. The aim of this study was to investigate the mechanisms underlying diabetic EPC dysfunction using methylglyoxal (MG), an endogenous toxic diabetic metabolite. Data demonstrated that MG decreased cell viability and protein expression of vascular endothelial growth factor receptor (VEGFR)-2 associated with functional impairment of tube formation in EPC. The generation of advanced glycation end (AGE) products was increased in EPC following exposure to MG. Blockage of receptor for AGE (RAGE) by FPS-ZM1, a specific antagonist for RAGE, significantly reversed the decrease of VEGFR-2 protein expression and angiogenic dysfunction in MG-incubated EPC. Taken together, data demonstrated that MG induced angiogenic impairment in EPC via alterations in the AGE/RAGE-VEGFR-2 pathway which may be utilized in the development of potential therapeutic and preventive targets for diabetic vascular complications.

BMP-2 induces angiogenesis by provoking integrin α6 expression in human endothelial progenitor cells

Bone morphogenetic protein-2 (BMP-2) is a multifunctional cytokine, capable of governing several cellular functions, including proliferation, motility, differentiation, and angiogenesis. Circulating endothelial progenitor cells (EPCs) have been shown to facilitate tissue repair, postnatal neovascularization, and tumor associated angiogenesis. Nevertheless, the impact of BMP-2 on angiogenesis of human EPCs has largely remained a mystery. In this study, we found that BMP-2 promoted cell migration and tube formation of EPCs in a concentration-dependent manner, indicating BMP-2 induced in vitro angiogenesis in human EPCs. Furthermore, BMP-2 significantly increased microvessel formation in Matrigel plug assay, and BMP-2 antagonist noggin prevented BMP-2-induced in vivo angiogenesis. Mechanistic investigations showed BMP-2 profoundly induced the expression of Id-1 and integrin α6 as well as EPCs angiogenesis by activating PI3K/Akt and MEK/ERK signaling pathways. Moreover, knockdown of Id-1 and integrin α6 by siRNA transfection obviously attenuated BMP-2-indueced tube formation of EPCs. These results suggest that BMP-2 promotes angiogenesis in human EPCs through the activation of PI3K/Akt, MEK/ERK, and Id-1/integrin α6 signaling cascades. This is the first demonstration that BMP-2 exhibits the angiogenesis property on human EPCs. BMP-2 might serve as the potential therapeutic target for treatment of angiogenesis-related diseases.

Resveratrol Improves Endothelial Progenitor Cell Function through miR-138 by Targeting Focal Adhesion Kinase (FAK) and Promotes Thrombus Resolution In Vivo

BACKGROUND Endothelial progenitor cells (EPCs) were found to be a potential therapeutic choice for low extremity deep vein thrombosis. The aim of our research was to investigate the effect of resveratrol (RSV) on EPCs that may promote thrombus resolution and its potential pathway. MATERIAL AND METHODS EPCs were pretreated with RSV and migration; angiogenesis were evaluated ex vivo. Expression of miR-138 and focal adhesion kinase (FAK) was also tested. A murine model of venous thrombosis was developed as an in vivo model. The effects of RSV treatment on mice with inferior venous thrombosis were evaluated. RESULTS We found that RSV increased EPCs migration and tube formation ex vivo. RSV significantly inhibited miR-138 expression. Moreover, we demonstrated that FAK was a target of miR-138 and revealed that FAK knockdown downregulated migration and angiogenesis of RSV-treated EPCs. In addition, RSV-induced EPCs promoted thrombus resolution in a murine model of venous thrombosis. CONCLUSIONS We found the first evidence that intravenous injection of RSV-treated EPCs enhanced thrombus resolution in vivo. RSV exerted its role by reducing miR-138 expression and therefore upregulated FAK.

Surface functionalization of electrospun scaffolds using recombinant human decorin attracts circulating endothelial progenitor cells

Decorin (DCN) is an important small leucine-rich proteoglycan present in the extracellular matrix (ECM) of many organs and tissues. Endothelial progenitor cells (EPCs) are able to interact with the surrounding ECM and bind to molecules such as DCN. Here, we recombinantly produced full-length human DCN under good laboratory practice (GLP) conditions, and after detailed immunological characterization, we investigated its potential to attract murine and human EPCs (mEPCs and hECFCs). Electrospun polymeric scaffolds were coated with DCN or stromal cell-derived factor-1 (SDF-1α) and were then dynamically cultured with both cell types. Cell viability was assessed via imaging flow cytometry. The number of captured cells was counted and compared with the non-coated controls. To characterize cell-scaffold interactions, immunofluorescence staining and scanning electron microscopy analyses were performed. We identified that DCN reduced T cell responses and attracted innate immune cells, which are responsible for ECM remodeling. A significantly higher number of EPCs attached on DCN- and SDF-1α-coated scaffolds, when compared with the uncoated controls. Interestingly, DCN showed a higher attractant effect on hECFCs than SDF-1α. Here, we successfully demonstrated DCN as promising EPC-attracting coating, which is particularily interesting when aiming to generate off-the-shelf biomaterials with the potential of in vivo cell seeding.

Role of Sertoli and Leydig Cells in the Regulation of Spermatogonial Stem Cell and Development of Reproductive Disorders in Male C57Bl/6 Mice with Type 1 Diabetes Mellitus

Course administration streptozotocin to male C57Bl/6 mice induces a complex of symptoms typical of type 1 diabetes mellitus: hyperglycemia and insulin deficiency, focal inflammatory infiltration of the pancreas, destructive changes in the Langerhans islets, damage to the insular apparatus (reduced number of PDX1⁺ cells and insulin expression by the secreting cells). Male reproductive disorder are serious complications of type 1 diabetes mellitus. In "diabetic" mice, interstitial edema with inflammatory infiltration and microvascular disorders in the testicular tissue are observed, the number of endothelial precursors (CD45^-/CD31⁺) and the total number and percentage of motile spermatozoa decreased, immature spermatogenic epithelium cells are desquamated of into the lumen of the tubules. Disturbances in the proliferation and differentiation of various spermatogonial stem cell populations (c-kit^-/CD90⁺, c-kit⁺/CD90⁺, and CD51^-/CD24⁺/CD52⁺) in diabetes can be explained by the inhibitory influence of inflammatory factors on testosterone-producing Leydig cells.

Identification of a novel angiogenic peptide from periostin

Angiogenic peptides have therapeutic potential for the treatment of chronic ischemic diseases. Periostin, an extracellular matrix protein expressed in injured tissues, promotes angiogenesis and tissue repair. We previously reported that in vivo administration of both recombinant full-length protein and the first FAS I domain of periostin alleviated peripheral artery occlusive disease by stimulating the migration of humane endothelial colony forming cells (ECFCs) and subsequent angiogenesis. In the present study, we ascertained the peptide sequence responsible for the periostin-induced angiogenesis. By serial deletion mapping of the first FAS I domain, we identified a peptide sequence (amino acids 142–151) of periostin for stimulation of chemotactic migration, adhesion, proliferation and endothelial tube formation of human ECFCs in vitro. Chemotactic migration of ECFCs induced by the periostin peptide was blocked by pre-incubation with an anti-β5 integrin neutralizing antibody. Treatment of ECFCs with the periostin peptide led to phosphorylation of both AKT and ERK, and pretreatment of ECFCs with the MEK-ERK pathway inhibitor U0126 or the PI3K-AKT pathway inhibitors, LY294002 or Wortmannin, blocked the periostin peptide-stimulated migration of ECFCs. These results suggest that the synthetic periostin peptide can be applied for stimulating angiogenic and therapeutic potentials of ECFCs.

Toll‑like receptor 4 is expressed and functional in late endothelial progenitor cells

It has been previously demonstrated that lipopolysaccharides (LPS) inhibit the viability, migration, adhesion and in vitro angiogenesis of late endothelial progenitor cells (EPCs). However, the mechanisms underlying this LPS‑induced impairment of late EPC functional activity are unknown. The aim of the present study was to investigate whether Toll‑like receptor 4 (TLR4) is expressed and functional on late EPCs, using late EPCs of 3‑5 passages. Cells were deprived of serum for 24 h prior to experiments and incubated with 10 µg/ml LPS for 24 h with or without pretreatment with 2 µg/ml TLR4 signaling inhibitor CLI‑095 for 30 min. The viability, migration, adhesion and in vitro angiogenesis, as well as the expression of silent information regulator 1 (SIRT1), in late EPCs were evaluated. Treatment with 10 µg/ml LPS decreased the viability, migration and adhesion abilities, and in vitro angiogenesis of late EPCs. Pretreatment with the TLR4 signaling inhibitor reversed this LPS‑induced dysfunction of late EPCs. LPS downregulated the expression of SIRT1 protein, however, blocking TLR4 attenuated the effect of LPS on SIRT1 expression. Therefore, the results of the present study indicate that LPS impaired the functional activity of late EPCs via TLR4, which may be associated with decreased SIRT1 expression.

MiR-27b augments bone marrow progenitor cell survival via suppressing the mitochondrial apoptotic pathway in Type 2 diabetes

Bone marrow-derived progenitor cells (BMPCs) are potential candidates for autologous cell therapy in tissue repair and regeneration because of their high angiogenic potential. However, increased progenitor cell apoptosis in diabetes directly limits their success in the clinic. MicroRNAs are endogenous noncoding RNAs that regulate gene expression at the posttranscriptional level, but their roles in BMPC-mediated angiogenesis are incompletely understood. In the present study, we tested the hypothesis that the proangiogenic miR-27b inhibits BMPC apoptosis in Type 2 diabetes. Bone marrow-derived EPCs from adult male Type 2 diabetic db/db mice and their normal littermates db/+ mice were used. MiR-27b expression (real-time PCR) in EPCs was decreased after 24 h of exposure to methylglyoxal (MGO) or oxidized low-density lipoprotein but not high glucose, advanced glycation end products, the reactive oxygen species generator LY83583, or H2O2 The increase in BMPC apoptosis in the diabetic mice was rescued following transfection with a miR-27b mimic, and the increased apoptosis induced by MGO was also rescued by the miR-27b mimic. p53 protein expression and the Bax/Bcl-2 ratio in EPCs (Western blot analyses) were significantly higher in db/db mice, both of which were suppressed by miR-27b. Furthermore, mitochondrial respiration, as measured by oxygen consumption rate, was enhanced by miR-27b in diabetic BMPCs, with concomitant decrease of mitochondrial Bax/Bcl-2 ratio. The 3' UTR binding assays revealed that both Bax, and its activator RUNX1, were direct targets of miR-27b, suggesting that miR-27b inhibits Bax expression in both direct and indirect manners. miR-27b prevents EPC apoptosis in Type 2 diabetic mice, at least in part, by suppressing p53 and the Bax/Bcl-2 ratio. These findings may provide a mechanistic basis for rescuing BMPC dysfunction in diabetes for successful autologous cell therapy.

Hedgehog-Interacting Protein (HIP) Regulates Apoptosis Evasion and Angiogenic Function of Late Endothelial Progenitor Cells

Late endothelial progenitor cells (LEPCs) are derived from mononuclear cells (MNCs) and are thought to directly incorporate into blood vessels and differentiate into mature endothelial cells (ECs). Using transcriptome and proteome analysis, we identified distinctive LEPC profiles and found that Hedgehog-interacting protein (HIP) is strongly expressed in LEPCs. Inhibition of HIP by lentiviral knockdown activated canonical hedgehog signaling in LEPCs, while it activated non-canonical hedgehog signaling in ECs. In LEPCs, HIP knockdown induced much enhanced tube formation and resistance to apoptosis under oxidative stress conditions via canonical hedgehog signaling. Although HIP is strongly expressed in proliferating LEPCs, HIP expression is down-regulated during angiogenesis and under oxidative stress condition. Moreover, when LEPCs are treated with angiogenic triggers such as VEGF and FGF2, HIP expression is reduced. Our findings suggest that HIP blocks LEPC angiogenesis and regulate survival when there is no angiogenic stimulation. HIP inhibition in LEPCs enhanced tube formation and reduced apoptosis, resulting in improved angiogenesis.

High glucose-induced endothelial progenitor cell dysfunction

Vascular complications contribute significantly to morbidity and mortality of diabetes mellitus. The primary cause of vascular complications in diabetes mellitus is hyperglycaemia, associated with endothelial dysfunction and impaired neovascularization. Circulating endothelial progenitor cells was shown to play important roles in vascular repair and promoting neovascularization. In this review, we will demonstrate the individual effect of high glucose on endothelial progenitor cells. Endothelial progenitor cells isolated from healthy subjects exposed to high glucose conditions or endothelial progenitor cells isolated from diabetic patients exhibit reduced number of endothelial cell colony forming units, impaired abilities of differentiation, proliferation, adhesion and migration, tubulization, secretion, mobilization and homing, whereas enhanced senescence. Increased production of reactive oxygen species by the mitochondria seems to play a crucial role in high glucose-induced endothelial progenitor cells deficit. Later, we will review the agents that might be used to alleviate dysfunction of endothelial progenitor cells induced by high glucose. The conclusions are that the relationship between hyperglycaemia and endothelial progenitor cells dysfunction is only beginning to be recognized, and future studies should pay more attention to the haemodynamic environment of endothelial progenitor cells and ageing factors to discover novel treatment agents.

Multiple therapeutic effect of endothelial progenitor cell regulated by drugs in diabetes and diabetes related disorder

BACKGROUND

Reduced levels of endothelial progenitor cells (EPCs) counts have been reported in diabetic mellitus (DM) patients and other diabetes-related disorder. EPCs are a circulating, bone marrow-derived cell population that appears to participate in vasculogenesis, angiogenesis and damage repair. These EPC may revert the damage caused in diabetic condition. We aim to identify several existing drugs and signaling molecule, which could alleviate or improve the diabetes condition via mobilizing and increasing EPC number as well as function.

MAIN BODY

Accumulated evidence suggests that dysregulation of EPC phenotype and function may be attributed to several signaling molecules and cytokines in DM patients. Hyperglycemia alone, through the overproduction of reactive oxygen species (ROS) via eNOS and NOX, can induce changes in gene expression and cellular behavior in diabetes. Furthermore, reports suggest that EPC telomere shortening via increased oxidative DNA damage may play an important role in the pathogenesis of coronary artery disease in diabetic patients. In this review, different type of EPC derived from different sources has been discussed along with cell-surface marker. The reduced number and immobilized EPC in diabetic condition have been mobilized for the therapeutic purpose via use of existing, and novel drugs have been discussed. Hence, evidence list of all types of drugs that have been reported to target the same pathway which affect EPC number and function in diabetes has been reviewed. Additionally, we highlight that proteins are critical in diabetes via polymorphism and inhibitor studies. Ultimately, a lucid pictorial explanation of diabetic and normal patient signaling pathways of the collected data have been presented in order to understand the complex signaling mystery underlying in the diseased and normal condition.

CONCLUSION

Finally, we conclude on eNOS-metformin-HSp90 signaling and its remedial effect for controlling the EPC to improve the diabetic condition for delaying diabetes-related complication. Altogether, the review gives a holistic overview about the elaborate therapeutic effect of EPC regulated by novel and existing drugs in diabetes and diabetes-related disorder.

Perinatal testosterone exposure potentiates vascular dysfunction by ERβ suppression in endothelial progenitor cells

Recent clinical cohort study shows that testosterone therapy increases cardiovascular diseases in men with low testosterone levels, excessive circulating androgen levels may play a detrimental role in the vascular system, while the potential mechanism and effect of testosterone exposure on the vascular function in offspring is still unknown. Our preliminary results showed that perinatal testosterone exposure in mice induces estrogen receptor β (ERβ) suppression in endothelial progenitor cells (EPCs) in offspring but not mothers, while estradiol (E2) had no effect. Further investigation showed that ERβ suppression is due to perinatal testosterone exposure-induced epigenetic changes with altered DNA methylation on the ERβ promoter. During aging, EPCs with ERβ suppression mobilize to the vascular wall, differentiate into ERβ-suppressed mouse endothelial cells (MECs) with downregulated expression of SOD2 (mitochondrial superoxide dismutase) and ERRα (estrogen-related receptor α). This results in reactive oxygen species (ROS) generation and DNA damage, and the dysfunction of mitochondria and fatty acid metabolism, subsequently potentiating vascular dysfunction. Bone marrow transplantation of EPCs that overexpressed with either ERβ or a SIRT1 single mutant SIRT1-C152(D) that could modulate SIRT1 phosphorylation significantly ameliorated vascular dysfunction, while ERβ knockdown worsened the problem. We conclude that perinatal testosterone exposure potentiates vascular dysfunction through ERβ suppression in EPCs.

Regenerative Potential of Spermatogonial Stem Cells, Endothelial Progenitor Cells, and Epithelial Progenitor Cells of C57Bl/6 Male Mice with Metabolic Disorders

The properties of spermatogonial stem cells, endothelial progenitor cells, and the epithelial progenitors of C57Bl/6 mice under conditions of metabolic disorders were studied using the model of busulfan-induced suppression of spermatogenesis and in vitro culture technique. Spermatogonial stem cells CD117-CD90⁺ and epithelial progenitors CD45-CD31-Sca-1⁺CD49f⁺ derived from the testes of mice with metabolic disturbances demonstrated 17- and 28-fold increase in the respective cell mass and generated cell colonies in vitro. In contrast, spermatogonial stem cells with immune phenotype CD51-CD24⁺CD52⁺ had reduced selfrenewal capacity. Spermatogonial stem cells CD117-CD90⁺ and CD117⁺CD90⁺ as well as endothelial progenitors CD45-CD31⁺ derived from the testes of donor mice with metabolic disorders demonstrated high transplantation capacity in C57Bl/6 mouse testes damaged by cytostatic busulfan.

Drug depot-anchoring hydrogel: A self-assembling scaffold for localized drug release and enhanced stem cell differentiation

Localized and long-term delivery of growth factors has been a long-standing challenge for stem cell-based tissue engineering. In the current study, a polymeric drug depot-anchoring hydrogel scaffold was developed for the sustained release of macromolecules to enhance the differentiation of stem cells. Self-assembling peptide (RADA16)-modified drug depots (RDDs) were prepared and anchored to a RADA16 hydrogel. The anchoring effect of RADA16 modification on the RDDs was tested both in vitro and in vivo. It was shown that the in vitro leakage of RDDs from the RADA16 hydrogel was significantly less than that of the unmodified drug depots (DDs). In addition, the in vivo retention of injected hydrogel-incorporated RDDs was significantly longer than that of hydrogel-incorporated unmodified DDs. A model drug, vascular endothelial growth factor (VEGF), was encapsulated in RDDs (V-RDDs) as drug depot that was then anchored to the hydrogel. The release of VEGF could be sustained for 4weeks. Endothelial progenitor cells (EPCs) were cultured on the V-RDDs-anchoring scaffold and enhanced cell proliferation and differentiation were observed, compared with a VEGF-loaded scaffold. Furthermore, this scaffold laden with EPCs promoted neovascularization in an animal model of hind limb ischemia. These results demonstrate that self-assembling hydrogel-anchored drug-loaded RDDs are promising for localized and sustained drug release, and can effectively enhance the proliferation and differentiation of resident stem cells, thus lead to successful tissue regeneration.

Zoledronate suppressed angiogenesis and osteogenesis by inhibiting osteoclasts formation and secretion of PDGF-BB

PURPOSE

Bisphosphonates related osteonecrosis of jaw (BRONJ) is a severe complication of systemic BPs administration, the mechanism of which is still unclarified. Recently, platelet-derived growth factor-BB (PDGF-BB) secreted by preosteoclasts was reported to promote angiogenesis and osteogenesis. This study aimed to clarify whether bisphosphonates suppressed preosteoclasts releasing PDGF-BB, and whether the suppression harmed coupling of angiogenesis and osteogenesis, which could contribute to BRONJ manifestation.

METHODS AND RESULTS

Zoledronate significantly inhibited osteoclast formation by tartrate-resistant acid phosphatase (TRAP) staining and PDGF-BB secretion tested by ELISA. In line with decreasing secretion of PDGF-BB by preosteoclasts exposed to zoledronate, conditioned medium (CM) from the cells significantly induced less migration of endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) compared to CM from unexposed preosteoclasts. Meanwhile, angiogenic function of EPCs and osteoblastic differentiation of MSCs also declined when culturing with CM from preosteoclasts treated by zoledronate (PZ-CM), evidenced by tube formation assay of EPCs and alkaline phosphatase activity of MSCs. Western blot assay showed that the expression of VEGF in EPCs and OCN, RUNX2 in MSCs declined when culturing with PZ-CM compared to CM from preostoeclasts without exposure of zoledronate.

CONCLUSION

Our study found that zoledronate was able to suppress preosteoclasts releasing PDGF-BB, resulting in suppression of angiogenesis and osteogenesis. Our study may partly contributed to the mechanism of BRONJ.

Effect of vitamin D on endothelial progenitor cells function

BACKGROUND

Endothelial progenitor cells (EPCs) are a population of bone marrow-derived cells, which have an important role in the process of endothelialization and vascular repair following injury. Impairment of EPCs, which occurs in patients with diabetes, was shown to be related to endothelial dysfunction, coronary artery disease (CAD) and adverse clinical outcomes. Recent evidence has shown that calcitriol, the active hormone of vitamin D, has a favorable impact on the endothelium and cardiovascular system. There is limited data on the effect of vitamin D on EPCs function.

AIM

To examine the in vitro effects of Calcitriol on EPCs from healthy subjects and patients with diabetes.

METHODS

Fifty-one patients with type 2 diabetes (60±11 years, 40% women, HbA1C: 9.1±0.8%) and 23 healthy volunteers were recruited. EPCs were isolated and cultured with and without calcitriol. The capacity of the cells to form colony-forming units (CFUs), their viability (measured by MTT assay), KLF-10 levels and angiogenic markers were evaluated after 1 week of culture.

RESULTS

In diabetic patients, EPC CFUs and cell viability were higher in EPCs exposed to calcitriol vs. EPCs not exposed to calcitriol [EPC CFUs: 1.25 (IQR 1.0-2.0) vs. 0.5 (IQR 0.5-1.9), p < 0.001; MTT:0.62 (IQR 0.44-0.93) vs. 0.52 (IQR 0.31-0.62), p = 0.001]. KLF-10 levels tended to be higher in EPCs exposed to vitamin D, with no differences in angiopoietic markers. In healthy subjects, calcitriol supplementation also resulted in higher cell viability [MTT: 0.23 (IQR 0.11-0.46) vs. 0.19 (0.09-0.39), p = 0.04], but without differences in CFU count or angiopoietic markers.

CONCLUSION

In patients with diabetes mellitus, in vitro vitamin D supplementation improved EPCs capacity to form colonies and viability. Further studies regarding the mechanisms by which vitamin D exerts its effect are required.

Pinocembrin ex vivo preconditioning improves the therapeutic efficacy of endothelial progenitor cells in monocrotaline-induced pulmonary hypertension in rats

Pulmonary hypertension is still not curable and the available current therapies can only alleviate symptoms without hindering the progression of disease. The present study was directed to investigate the possible modulatory effect of pinocembrin on endothelial progenitor cells transplanted in monocrotaline-induced pulmonary hypertension in rats. Pulmonary hypertension was induced by a single subcutaneous injection of monocrotaline (60mg/kg). Endothelial progenitor cells were in vitro preconditioned with pinocembrin (25mg/L) for 30min before being i.v. injected into rats 2weeks after monocrotaline administration. Four weeks after monocrotaline administration, blood pressure, electrocardiography and right ventricular systolic pressure were recorded. Rats were sacrificed and serum was separated for determination of endothelin-1 and asymmetric dimethylarginine levels. Right ventricles and lungs were isolated for estimation of tumor necrosis factor-alpha and transforming growth factor-beta contents as well as caspase-3 activity. Moreover, protein expression of matrix metalloproteinase-9 and endothelial nitric oxide synthase in addition to myocardial connexin-43 was assessed. Finally, histological analysis of pulmonary arteries, cardiomyocyte cross-sectional area and right ventricular hypertrophy was performed and cryosections were done for estimation of cell homing. Preconditioning with pinocembrin provided a significant improvement in endothelial progenitor cells' effect towards reducing monocrotaline-induced elevation of inflammatory, fibrogenic and apoptotic markers. Furthermore, preconditioned cells induced a significant amelioration of endothelial markers and cell homing and prevented monocrotaline-induced changes in right ventricular function and histological analysis compared with native cells alone. In conclusion, pinocembrin significantly improves the therapeutic efficacy of endothelial progenitor cells in monocrotaline-induced pulmonary hypertension in rats.

Human Stem Cell-Derived Endothelial-Hepatic Platform for Efficacy Testing of Vascular-Protective Metabolites from Nutraceuticals

Atherosclerosis underlies many cardiovascular and cerebrovascular diseases. Nutraceuticals are emerging as a therapeutic moiety for restoring vascular health. Unlike small-molecule drugs, the complexity of ingredients in nutraceuticals often confounds evaluation of their efficacy in preclinical evaluation. It is recognized that the liver is a vital organ in processing complex compounds into bioactive metabolites. In this work, we developed a coculture system of human pluripotent stem cell-derived endothelial cells (hPSC-ECs) and human pluripotent stem cell-derived hepatocytes (hPSC-HEPs) for predicting vascular-protective effects of nutraceuticals. To validate our model, two compounds (quercetin and genistein), known to have anti-inflammatory effects on vasculatures, were selected. We found that both quercetin and genistein were ineffective at suppressing inflammatory activation by interleukin-1β owing to limited metabolic activity of hPSC-ECs. Conversely, hPSC-HEPs demonstrated metabolic capacity to break down both nutraceuticals into primary and secondary metabolites. When hPSC-HEPs were cocultured with hPSC-ECs to permit paracrine interactions, the continuous turnover of metabolites mitigated interleukin-1β stimulation on hPSC-ECs. We observed significant reductions in inflammatory gene expressions, nuclear translocation of nuclear factor κB, and interleukin-8 production. Thus, integration of hPSC-HEPs could accurately reproduce systemic effects involved in drug metabolism in vivo to unravel beneficial constituents in nutraceuticals. This physiologically relevant endothelial-hepatic platform would be a great resource in predicting the efficacy of complex nutraceuticals and mechanistic interrogation of vascular-targeting candidate compounds. Stem Cells Translational Medicine 2017;6:851-863.

Beneficial Effects of Reconstituted High-Density Lipoprotein (rHDL) on Circulating CD34+ Cells in Patients after an Acute Coronary Syndrome

Background

High-density lipoproteins (HDL) favorably affect endothelial progenitor cells (EPC). Circulating progenitor cell level and function are impaired in patients with acute coronary syndrome (ACS). This study investigates the short-term effects of reconstituted HDL (rHDL) on circulating progenitor cells in patients with ACS.

Methods and Findings

The study population consisted of 33 patients with recent ACS: 20 patients from the ERASE trial (randomized to receive 4 weekly intravenous infusions of CSL-111 40 mg/kg or placebo) and 13 additional patients recruited as controls using the same enrolment criteria. Blood was collected from 16 rHDL (CSL-111)-treated patients and 17 controls at baseline and at 6–7 weeks (i.e. 2–3 weeks after the fourth infusion of CSL-111 in ERASE). CD34⁺ and CD34⁺/kinase insert domain receptor (KDR⁺) progenitor cell counts were analyzed by flow cytometry. We found preserved CD34⁺ cell counts in CSL-111-treated subjects at follow-up (change of 1.6%), while the number of CD34⁺ cells was reduced (-32.9%) in controls (p = 0.017 between groups). The level of circulating SDF-1 (stromal cell-derived factor-1), a chemokine involved in progenitor cell recruitment, increased significantly (change of 21.5%) in controls, while it remained unchanged in CSL-111-treated patients (p = 0.031 between groups). In vitro exposure to CSL-111 of early EPC isolated from healthy volunteers significantly increased CD34⁺ cells, reduced early EPC apoptosis and enhanced their migration capacity towards SDF-1.

Conclusions

The relative increase in circulating CD34⁺ cells and the low SDF-1 levels observed following rHDL infusions in ACS patients point towards a role of rHDL in cardiovascular repair mechanisms.

Advanced Glycation Endproducts Impair Endothelial Progenitor Cell Migration and Homing via Syndecan 4 Shedding

Endothelial progenitor cells (EPCs) are a subtype of bone marrow-derived progenitor cells. Stromal cell-derived factor 1 (SDF-1)-mediated EPC mobilization from bone marrow to areas of ischemia plays an important role in angiogenesis. Previous studies have reported that advanced glycation endproducts (AGEs), which are important mediators of diabetes-related vascular pathology, may impair EPC migration and homing, but the mechanism is unclear. Syndecan-4 (synd4) is a ubiquitous heparan sulfate proteoglycan receptor on the cell surface, involved in SDF-1-dependent cell migration. The extracellular domain of synd4 (ext-synd4) is shed in the context of acute inflammation, but the shedding of ext-synd4 in response to AGEs is undefined. Here we investigated changes in ext-synd4 on EPCs in response to AGEs, focusing on the influence of impaired synd4 signaling on EPC migration and homing. We found decreased full length and increased residue of synd4 in cells incubated with AGEs, with concomitant increase in the soluble fragment of ext-synd4 in the cell medium. EPCs from patients with type 2 diabetes expressed less ext-synd4 as assessed by Western blotting. Flow cytometry analysis showed less ext-synd4 on circulating CD34⁺ peripheral blood mononuclear cells, of which EPCs form a subgroup. We then explored the role of synd4 in EPC migration and homing. Impaired migration of synd4-deficient EPCs was observed by a 2D-chemotaxis slide. Furthermore, poor homing of synd4-/- EPCs was observed in a mouse model of lower limb ischemia. This study demonstrates that the shedding of synd4 from EPCs plays a key role in AGE-mediated dysfunction of EPC migration and homing. Stem Cells 2017;35:522-531.