Regulation of Cell Cycle in Hematopoietic Stem Cells by the Niche

The quiescent state is thought to be an indispensable property for the maintenance of hematopoietic stem cells (HSCs). Interaction of HSCs with their particular microenvironments, known as the stem cell niches, is critical for cell cycle regulation of HSCs. Monitoring of the quiescence of HSCs using by a new stem cell marker, Side Population (SP), revealed that the cell cycle status of HSCs is dynamically controlled by the microenvironments. We have recently revealed a molecular mechanism in which cell cycle of HSCs is regulated by the niche. HSCs expressing the receptor tyrosine kinase Tie2 are adhere to osteoblasts (OBs) in the BM niche. The interaction of Tie2 and its ligand Angiopoietin-1 (Ang-1) leads to tight adhesion of HSCs to stromal cells, resulting in maintainance of long-term repopulating activity of HSCs. Thus, Tie2/Ang-1 signaling pathway plays a critical role in the maintenance of HSCs in a quiescent state in the BM niche. The understanding of cell cycle control in stem cells leads to development of new strategy for progress in regenerative medicine.

A comparative study of non-viral gene delivery techniques to human adipose-derived mesenchymal stem cell

Mesenchymal stem cells (MSCs) hold tremendous potential for therapeutic use in stem cell-based gene therapy. Ex vivo genetic modification of MSCs with beneficial genes of interest is a prerequisite for successful use of stem cell-based therapeutic applications. However, genetic manipulation of MSCs is challenging because they are resistant to commonly used methods to introduce exogenous DNA or RNA. Herein we compared the effectiveness of several techniques (classic calcium phosphate precipitation, cationic polymer, and standard electroporation) with that of microporation technology to introduce the plasmid encoding for angiopoietin-1 (ANGPT-1) and enhanced green fluorescent protein (eGFP) into human adipose-derived MSCs (hAD-MSCs). The microporation technique had a higher transfection efficiency, with up to 50% of the viable hAD-MSCs being transfected, compared to the other transfection techniques, for which less than 1% of cells were positive for eGFP expression following transfection. The capability of cells to proliferate and differentiate into three major lineages (chondrocytes, adipocytes, and osteocytes) was found to be independent of the technique used for transfection. These results show that the microporation technique is superior to the others in terms of its ability to transfect hAD-MSCs without affecting their proliferation and differentiation capabilities. Therefore, this study provides a foundation for the selection of techniques when using ex vivo gene manipulation for cell-based gene therapy with MSCs as the vehicle for gene delivery.

[Expression changes of Ang-1, Ang-2, Tie-2 and VEGF in co-culturing of endothelial cells and astrocytes after irradiation by X-ray and their significances]

OBJECTIVE

To explore the possible relationship between angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), Tie-2 and vascular endothelial growth factor (VEGF) and radiation brain injury (RBI) and detect the expressions of VEGF, Ang-1, Ang-2 and Tie-2 in co-cultured endothelial cells and astrocytes after an irradiation of X-ray.

METHODS

Murine brain microvascular endothelial cells bEnd.3 and astrocytes were co-cultured in a Transwell culture plate and then exposed to X-ray at various doses (5, 10, 20 and 30 Gy) and cultured for 24 hours. The group without radiation acted as a control. Western blot was used to detect the expressions of VEGF, Ang-1, Ang-2 and Tie-2.

RESULTS

As compared with the control group, the expression of VEGF increased in 5, 10, 20 and 30 Gy dose groups [(1.71 ± 0.11), (2.03 ± 0.05), (2.20 ± 0.06), (2.19 ± 0.08) vs (1.26 ± 0.10), P < 0.05]; the expression of Ang-1 decreased in 5, 10, 20 and 30 Gy dose groups [(2.27 ± 0.07), (2.28 ± 0.06), (2.01 ± 0.05), (1.54 ± 0.08) vs (2.46 ± 0.04), P < 0.05]; the expression of Tie-2 decreased in 5, 10, 20 and 30 Gy dose groups [(2.40 ± 0.10), (2.47 ± 0.06), (1.05 ± 0.09), (1.00 ± 0.08)vs(4.80 ± 0.07), P < 0.05]; the expression of Ang-2 increased in 5 Gy and 10 Gy dose groups [(2.10 ± 0.07), (2.43 ± 0.08)vs (1.69 ± 0.05), P < 0.05] while decreased in 20 Gy and 30 Gy dose groups [(1.12 ± 0.10), (1.21 ± 0.04)vs(1.69 ± 0.05), P < 0.05].

CONCLUSION

X-ray could differentially affect the expressions of VEGF, Ang-1, Ang-2 and Tie-2 in co-cultured endothelial cells and astrocytes. And the differential expressions of VEGF, Ang-1, Ang-2 and Tie-2 may be related with microvascular injury in RBI.

Effects of angiopoietin-1 on hemorrhagic transformation and cerebral edema after tissue plasminogen activator treatment for ischemic stroke in rats

An angiogenesis factor, angiopoietin-1 (Ang1), is associated with the blood-brain barrier (BBB) disruption after focal cerebral ischemia. However, whether hemorrhagic transformation and cerebral edema after tissue plasminogen activator (tPA) treatment are related to the decrease in Ang1 expression in the BBB remains unknown. We hypothesized that administering Ang1 might attenuate hemorrhagic transformation and cerebral edema after tPA treatment by stabilizing blood vessels and inhibiting hyperpermeability. Sprague-Dawley rats subjected to thromboembolic focal cerebral ischemia were assigned to a permanent ischemia group (permanent middle cerebral artery occlusion; PMCAO) and groups treated with tPA at 1 h or 4 h after ischemia. Endogenous Ang1 expression was observed in pericytes, astrocytes, and neuronal cells. Western blot analyses revealed that Ang1 expression levels on the ischemic side of the cerebral cortex were decreased in the tPA-1h, tPA-4h, and PMCAO groups as compared to those in the control group (P = 0.014, 0.003, and 0.014, respectively). Ang1-positive vessel densities in the tPA-4h and PMCAO groups were less than that in the control group (p = 0.002 and <0.001, respectively) as well as that in the tPA-1h group (p = 0.047 and 0.005, respectively). These results suggest that Ang1-positive vessel density was maintained when tPA was administered within the therapeutic time window (1 h), while it was decreased when tPA treatment was given after the therapeutic time window (4 h). Administering Ang1 fused with cartilage oligomeric protein (COMP) to supplement this decrease has the potential to suppress hemorrhagic transformation as measured by hemoglobin content in a whole cerebral homogenate (p = 0.007) and cerebral edema due to BBB damage (p = 0.038), as compared to administering COMP protein alone. In conclusion, Ang1 might be a promising target molecule for developing vasoprotective therapies for controlling hemorrhagic transformation and cerebral edema after tPA treatment.

Hydrogen sulfide improves wound healing via restoration of endothelial progenitor cell functions and activation of angiopoietin-1 in type 2 diabetes

Impaired angiogenesis and its induced refractory wound lesions are common complications of diabetes. Hydrogen sulfide (H2S) has been reported to have proangiogenic effects. We hypothesize that H2S improves diabetic wound healing by restoring endothelial progenitor cell (EPC) function in type 2 diabetes. db/db Mice were treated with sodium hydrosulfide (NaHS), 4-hydro-xythiobenzamide group (HTB), or saline for 18 days. db/+ Mice were treated with dl-propargylglycine (PAG) or saline for 18 days. Plasma H2S levels were significantly decreased in db/db mice and restored in the NaHS and HTB mice compared with the diabetic control group. Wound-closure rates were significantly faster in the NaHS and HTB groups than in the db/db group, in which the PAG group had slower wound-closure rates. Wound skin capillary densities were enhanced in the NaHS and HTB groups. EPC functions were significantly preserved in the NaHS and HTB groups but were decreased in the PAG group. Meanwhile, EPC functions of the db/+ mice were significantly reduced after in vitro PAG treatment or cystathionine-γ-lyase (CSE) silencing; EPC functions of db/db mice were significantly improved after in vitro NaHS treatment. The expressions of Ang-1 in wound skin tissue and in EPCs were upregulated in the NaHS and HTB groups compared with db/db controls, but were downregulated by in vivo PAG and in vitro siCSE treatment compared with normal controls. Diabetic EPC tube formation capacity was significantly inhibited by Ang-1 small interfering RNA before NaHS treatment compared with db/db EPCs treated with NaHS only. Taken together, these results show that H2S improves wound healing by restoration of EPC functions and activation of Ang-1 in type 2 diabetic mice.

Angiopoietin-1 upregulates de novo expression of IL-1β and Il1-Ra, and the exclusive release of Il1-Ra from human neutrophils

The expression of the angiopoietin (Ang) receptor, Tie2, on both endothelial and inflammatory cells supports the idea that Ang signaling may play a fundamental role in initiating and maintaining the inflammatory response. We have previously shown that Ang1 and/or Ang2 alter the innate immune response by enhancing human neutrophil survival, chemotaxis and production of inflammatory cytokine interleukin-8 (IL-8) in vitro. Thus, we hypothesized that Ang1 and Ang2 could modulate other inflammatory signals in neutrophils, a possibility we explored through a gene-based assay looking at changes in the mRNA expression of 84 inflammatory cytokines and their receptors. We observed that Ang1 (10(-8) M), but not Ang2, increased mRNA expression of prominent pro-inflammatory cytokine IL-1β and its natural antagonist IL-1RA, by up to 32.6- and 10.0-fold respectively, compared to PBS-control. The effects of Ang1 extended to the proteins, as Ang1 increased intracellular levels of precursor and mature IL-1β, and extracellular levels of IL-1RA proteins, by up to 4.2-, 5.0- and 4.4-fold respectively, compared to PBS-control. Interestingly, Ang1 failed at inducing IL-1β protein release or at increasing intracellular IL-1RA, but the ratio of IL-1RA to mature IL-1β remained above 100-fold molar excess inside and outside the cells. The above-noted effects of Ang1 were mediated by MAP kinases, whereby inhibiting MEK1/2 lead to up to 70% effect reduction, whereas the blockade of p38MAPK activity doubled Ang1's effect. These findings suggest that Ang1 selectively alters the balance of neutrophil-derived inflammatory cytokines, favoring the blockade of IL-1 activity, a consideration for future therapies of inflammatory diseases.

Tie1 deletion inhibits tumor growth and improves angiopoietin antagonist therapy

The endothelial Tie1 receptor is ligand-less, but interacts with the Tie2 receptor for angiopoietins (Angpt). Angpt2 is expressed in tumor blood vessels, and its blockade inhibits tumor angiogenesis. Here we found that Tie1 deletion from the endothelium of adult mice inhibits tumor angiogenesis and growth by decreasing endothelial cell survival in tumor vessels, without affecting normal vasculature. Treatment with VEGF or VEGFR-2 blocking antibodies similarly reduced tumor angiogenesis and growth; however, no additive inhibition was obtained by targeting both Tie1 and VEGF/VEGFR-2. In contrast, treatment of Tie1-deficient mice with a soluble form of the extracellular domain of Tie2, which blocks Angpt activity, resulted in additive inhibition of tumor growth. Notably, Tie1 deletion decreased sprouting angiogenesis and increased Notch pathway activity in the postnatal retinal vasculature, while pharmacological Notch suppression in the absence of Tie1 promoted retinal hypervasularization. Moreover, substantial additive inhibition of the retinal vascular front migration was observed when Angpt2 blocking antibodies were administered to Tie1-deficient pups. Thus, Tie1 regulates tumor angiogenesis, postnatal sprouting angiogenesis, and endothelial cell survival, which are controlled by VEGF, Angpt, and Notch signals. Our results suggest that targeting Tie1 in combination with Angpt/Tie2 has the potential to improve antiangiogenic therapy.

Microvascular protective role of pericytes in melatonin-treated spinal cord injury in the C57BL/6 mice

BACKGROUND

Pericytes, located on microvessels, help to maintain vascular stability and blood-brain barrier integrity. The influence of pericytes on microvessels after spinal cord injury (SCI) is less clear. Therefore, the aim of this study was to investigate whether pericytes took a protective effect on microvessels in melatonin-treated SCI.

METHODS

C57BL/6 mice were randomly divided into three groups: sham group, SCI group, and melatonin group (n = 27 per group). Functional recovery was evaluated using the Basso Mouse Scale. Motor neurons were observed using hematoxylin and eosin staining. Pericyte coverage was analyzed using immunofluorescence. Permeability of blood-spinal cord barrier (BSCB) was assessed by administration of Evan's Blue. Protein levels of occludin, aquaporin-4 (AQP4), angiopoietin-1 (Ang1), intercellular cell adhesion molecule-1 (ICAM-1), Bcl-2, and Bax were determined using Western blotting. Mimicking the pathological conditions of SCI, melatonin-treated primary pericytes were subjected to oxygen-glucose deprivation/reperfusion (OGD/R). Secretion of Ang1 was analyzed using an enzyme-linked immunosorbent assay, and the expression of ICAM-1 was detected by immunofluorescence.

RESULTS

Melatonin treatment improved locomotor functional outcome and rescued motor neurons. Pericyte coverage was significantly reduced after SCI; melatonin treatment alleviated the loss of pericyte coverage and rescued perfused microvessels 7 days after injury. The permeability of BSCB and loss of occludin were attenuated, and edema formation and upregulation of AQP4 were inhibited, after melatonin treatment. The expression of Ang1 and Bcl-2 was improved, while the expression of ICAM-1 and Bax was inhibited, in melatonin-treated SCI mice. Furthermore, the secretion of Ang1 was increased and the expression of ICAM-1 was inhibited in melatonin-treated pericytes after OGD/R.

CONCLUSIONS

Melatonin ameliorated the loss of blood vessels and disruption of BSCB to exert a protective effect on SCI, which might be mediated by increased pericyte coverage. The upregulation of Ang1 in pericytes could inhibit inflammation and apoptosis to protect the microvessels.

Adipose-derived mesenchymal stromal cells from aged patients with coronary artery disease keep mesenchymal stromal cell properties but exhibit characteristics of aging and have impaired angiogenic potential

Tissue regeneration is impaired in aged individuals. Adipose-derived mesenchymal stromal cells (ADSCs), a promising source for cell therapy, were shown to secrete various angiogenic factors and improve vascularization of ischemic tissues. We analyzed how patient age affected the angiogenic properties of ADSCs. ADSCs were isolated from subcutaneous fat tissue of patients with coronary artery disease (CAD; n = 64, 43-77 years old) and without CAD (n = 31, 2-82 years old). ADSC phenotype characterized by flow cytometry was CD90(+)/CD73(+)/CD105(+)/CD45(-)/CD31(-) for all samples, and these cells were capable of adipogenic and osteogenic differentiation. ADSCs from aged patients had shorter telomeres (quantitative reverse transcription polymerase chain reaction) and a tendency to attenuated telomerase activity. ADSC-conditioned media (ADSC-CM) stimulated capillary-like tube formation by endothelial cells (EA.hy926), and this effect significantly decreased with the age of patients both with and without CAD. Angiogenic factors (vascular endothelial growth factor, placental growth factor, hepatocyte growth factor, angiopoetin-1, and angiogenin) in ADSC-CM measured by enzyme-linked immunosorbent assay significantly decreased with patient age, whereas levels of antiangiogenic factors thrombospondin-1 and endostatin did not. Expression of angiogenic factors in ADSCs did not change with patient age (real-time polymerase chain reaction); however, gene expression of factors related to extracellular proteolysis (urokinase and its receptor, plasminogen activator inhibitor-1) and urokinase-type plasminogen activator receptor surface expression increased in ADSCs from aged patients with CAD. ADSCs from aged patients both with and without CAD acquire aging characteristics, and their angiogenic potential declines because of decreasing proangiogenic factor secretion. This could restrict the effectiveness of autologous cell therapy with ADSCs in aged patients.

Increased intravitreal angiopoietin-2 levels associated with rhegmatogenous retinal detachment

PURPOSE

To explore factors related to pathogenesis of rhegmatogenous retinal detachment (RRD) and development of proliferative vitreoretinopathy (PVR), vitreous levels of angiopoietin-1 and -2 (Ang-1 and -2), previously undefined in RRD, transforming growth factor-(TGF) β1, vascular endothelial growth factor (VEGF), erythropoietin (EPO) and proteolytic mediators of extracellular matrix remodelling (MMP-2 and -9) were compared in eyes with RRD and eyes with idiopathic macular hole or pucker.

METHODS

Vitreous samples were collected from 117 eyes with RRD (study group) and 40 eyes with macular hole or pucker (control group). Growth factors were measured by ELISA and matrix metalloproteinases (MMPs) by gelatin zymography.

RESULTS

The mean vitreous concentrations of Ang-2, MMP-2, and MMP-9 were higher (all p < 0.01), whereas concentration of VEGF was lower (p = 0.01) in eyes with RRD relative to controls. Logistic regression analysis identified Ang-2 concentration as a novel marker of RRD (p = 0.0001, OR 48.7). Ang-1, EPO, and total TGF-β1 levels were not significantly different between the groups. However, TGF-β1 and MMP-2 were increased in eyes with total RRD compared to those with local RRD (p ≤ 0.05). In eyes with PVR, no differences were observed in any studied marker as compared with non-PVR eyes.

CONCLUSIONS

Current results reveal Ang-2 as a key factor upregulated in RRD. It may co-operate with fibrosis-associated factors and contribute to vascular complications such as breakdown of blood-eye barrier and PVR development.

Inhibitory effect of glyceollins on vasculogenesis through suppression of endothelial progenitor cell function

SCOPE

Endothelial progenitor cells (EPCs) are derived from hematopoietic stem cells, and have the ability to differentiate into mature endothelial cells and contribute to neovascularization. Glyceollins are a type of phytoalexin produced in soybeans under stress conditions. The aim of this study is to determine the effect of glyceollin treatment on EPCs during early tumor vasculogenesis.

METHODS AND RESULTS

We found that glyceollin treatment significantly decreased the number of EPC colony-forming units in human cord blood-derived AC133⁺ cells and mouse bone-marrow-derived c-Kit⁺/Sca-1⁺/Lin⁻ cells. Glyceollin treatment diminished the number of lineage-committed EPC cells in a dose-dependent manner (1-20 μM). Glyceollin treatment inhibited EPC migration, tube formation and the mRNA expression of angiopoietin-1 (Ang-1), Tie-2, stromal-derived factor-1 (SDF-1), C-X-C-chemokine receptor-4 (CXCR4), and endothelial nitric oxide synthase (eNOS) in cultured EPCs. Glyceollin treatment suppressed activation of Akt, Erk, and eNOS induced by SDF-1α or vascular endothelial growth factor (VEGF). Treatment with 10 mg/kg glyceollins significantly reduced the number of tumor-induced circulating EPCs and the incorporation of EPCs into neovessels in bone marrow transplanted mice.

CONCLUSION

These results suggest that glyceollins inhibit the function of EPCs in tumor neovascularization. Glyceollins from soybean elicitation could be beneficial in prevention of cancer development via vasculogenesis.

[Influence of negative pressure wound therapy on the angiogenesis of wounds in diabetic rats]

OBJECTIVE

To observe the influence of negative pressure wound therapy on the angiogenesis of wounds in diabetic rats.

METHODS

Diabetes model was reproduced by intraperitoneal injection of 20 g/L streptozotocin in the dosage of 65 mg/kg in 40 SD rats. Two weeks later, rats were divided into control group (C) and negative pressure group (NP) according to the random number table, with 20 rats in each group. A piece of full-thickness skin in the center of the back of each rat in the size of 2 cm×2 cm was excised to produce a wound. Immediately after injury, wounds in group C were given conventional dressing change; wounds in group NP were treated with continuous negative pressure (-16.0 kPa) therapy for four hours a day, which lasted for seven days. (1) Blood glucose and body weight of rats in two groups were respectively measured by glucose meter and electronic scale before treatment, and 1 and 2 week (s) after. (2) Wound blood flow was detected by laser Doppler perfusion imager before treatment and on post treatment day (PTD) 1, 3, 7, with 5 rats at each time point. (3) On PTD 3 and 7, respectively, five rats from each group were sacrificed. The wound tissue was excised and divided into two parts. The angiogenesis in the left part tissue was observed with immunohistochemical staining. The microvessel density was calculated. (4) The full-thickness skin excised before treatment and the right part tissue freeze on PTD 3 and 7 were collected. On PTD 1 and 14, wound tissue was excised in the above-mentioned method. The mRNA levels of the vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 1 (Fit-1), angiopoietin 1 (Ang-1), Ang-2, and tyrosine kinase receptor 2 (Tie-2) were determined with real-time fluorescence quantification PCR. Data were processed with two-way analysis of variance or LSD-t test.

RESULTS

(1) No significant difference was observed between two groups in blood glucose level and body weight as a whole or at each time point (with F values respectively 0.667, 0.176, t values from 0.311 to 0.707, P values all above 0.05). (2) The difference in the overall wound blood flow of rats between two groups was significant (F = 24.66, P < 0.05). On PTD 1, 3, 7, values of wound blood flow of rats in group NP were (179 ± 24), (219 ± 12), (192 ± 30) perfusion unit, significantly higher than those of rats in group C[(127 ± 16), (179 ± 8), (144 ± 17) perfusion unit, with t values respectively 3.71, 5.57, 2.77, P < 0.05 or P < 0.01]. (3) The difference in the overall microvessel density in the wound of rats between two groups was significant (F = 33.25, P < 0.05). On PTD 3, the microvessel density in the wound of rats in group NP was (80 ± 12) per 100-time visual field, which was significantly higher than that of group C[(38 ± 4) per 100-time visual field, t = 9.257, P < 0.05]. On PTD 7, the microvessel density in the wound of rats in two groups were close (t = 1.159, P > 0.05), but the vessels in group NP were regularly arranged with spacious lumen, while the vessels in group C were disorderly arranged with narrow lumen. (4) On PTD 1, 3, mRNA expression levels of VEGF, Fit-1, and Ang-1 in group NP were obviously higher than those in group C (with t values from 1.28 to 11.60, P values all below 0.01). On PTD 7, the mRNA expression level of Ang-1 (27.59 ± 3.55) in group NP was obviously higher than that in group C (19.87 ± 1.86, t = 7.23, P < 0.001), while the mRNA level of its antagonist Ang-2 (5.79 ± 0.61) in group NP was obviously lower than that in group C (17.62 ± 0.85, t = 19.88, P < 0.001). On PTD 3, 7, 14, mRNA levels of Tie-2 in group NP were obviously lower than those in group C (with t values from 8.92 to 15.60, P values all below 0.01).

CONCLUSIONS

Negative pressure wound therapy may promote wound angiogenesis by enhancing the expression of Ang-1 and lowering the expression of Ang-2 in diabetic rats.

Comparative analysis of human mesenchymal stem cells from bone marrow, adipose tissue, and umbilical cord blood as sources of cell therapy

Various source-derived mesenchymal stem cells (MSCs) have been considered for cell therapeutics in incurable diseases. To characterize MSCs from different sources, we compared human bone marrow (BM), adipose tissue (AT), and umbilical cord blood-derived MSCs (UCB-MSCs) for surface antigen expression, differentiation ability, proliferation capacity, clonality, tolerance for aging, and paracrine activity. Although MSCs from different tissues have similar levels of surface antigen expression, immunosuppressive activity, and differentiation ability, UCB-MSCs had the highest rate of cell proliferation and clonality, and significantly lower expression of p53, p21, and p16, well known markers of senescence. Since paracrine action is the main action of MSCs, we examined the anti-inflammatory activity of each MSC under lipopolysaccharide (LPS)-induced inflammation. Co-culture of UCB-MSCs with LPS-treated rat alveolar macrophage, reduced expression of inflammatory cytokines including interleukin-1α (IL-1α), IL-6, and IL-8 via angiopoietin-1 (Ang-1). Using recombinant Ang-1 as potential soluble paracrine factor or its small interference RNA (siRNA), we found that Ang-1 secretion was responsible for this beneficial effect in part by preventing inflammation. Our results demonstrate that primitive UCB-MSCs have biological advantages in comparison to adult sources, making UCB-MSCs a useful model for clinical applications of cell therapy.

Dickkopf-related protein 3 promotes pathogenic stromal remodeling in benign prostatic hyperplasia and prostate cancer

BACKGROUND

Compartment-specific epithelial and stromal expression of the secreted glycoprotein Dickkopf-related protein (Dkk)-3 is altered in age-related proliferative disorders of the human prostate. This study aimed to determine the effect of Dkk-3 on prostate stromal remodeling that is stromal proliferation, fibroblast-to-myofibroblast differentiation and expression of angiogenic factors in vitro.

METHODS

Lentiviral-delivered overexpression and shRNA-mediated knockdown of DKK3 were applied to primary human prostatic stromal cells (PrSCs). Cellular proliferation was analyzed by BrdU incorporation ELISA. Expression of Dkk-3, apoptosis-related genes, cyclin-dependent kinase inhibitors and angiogenic factors were analyzed by qPCR, Western blot analysis or ELISA. Fibroblast-to-myofibroblast differentiation was monitored by smooth muscle cell actin and insulin-like growth factor binding protein 3 mRNA and protein levels. The relevance of Wnt/β-catenin and PI3K/AKT signaling pathways was assessed by cytoplasmic/nuclear β-catenin levels and phosphorylation of AKT.

RESULTS

Knockdown of DKK3 significantly attenuated PrSC proliferation as well as fibroblast-to-myofibroblast differentiation and increased the expression of the vessel stabilizing factor angiopoietin-1. DKK3 knockdown did not affect subcellular localization or levels of β-catenin but attenuated AKT phosphorylation in PrSCs. Consistently the PI3K/AKT inhibitor LY294002 mimicked the effects of DKK3 knockdown.

CONCLUSIONS

Dkk-3 promotes fibroblast proliferation and myofibroblast differentiation and regulates expression of angiopoietin-1 in prostatic stroma potentially via enhancing PI3K/AKT signaling. Thus, elevated Dkk-3 in the stroma of the diseased prostate presumably regulates stromal remodeling by enhancing proliferation and differentiation of stromal cells and contributing to the angiogenic switch observed in BPH and PCa. Therefore, Dkk-3 represents a potential therapeutic target for stromal remodeling in BPH and PCa.

Ang-2 upregulation correlates with increased levels of MMP-9, VEGF, EPO and TGFβ1 in diabetic eyes undergoing vitrectomy

PURPOSE

Angiogenesis in diabetic retinopathy (DR) is a multifactorial process regulated by hypoxia-induced growth factors and inflammatory cytokines. In addition to the angiogenic switch, the proteolytic processing and altered synthesis of the extracellular matrix are critical steps in this disease. This study was performed to evaluate the levels of matrix metalloproteinase-2 and matrix metalloproteinase-9 (MMP-2 and MMP-9), angiopoietin-1 and angiopoietin-2 (Ang-1 and Ang-2), vascular endothelial growth factor (VEGF), erythropoietin (EPO) and transforming growth factor-β1 (totalTGFβ1) in the vitreous of diabetic eyes undergoing vitrectomy compared with control eyes operated because of macular hole or pucker.

METHODS

Prospective consecutive controlled observational study performed in the unit of vitreoretinal surgery in Finland during the years 2006-2008. Vitreous samples were collected before the start of the conventional 3-ppp vitrectomy. Vitreous MMP-2 and MMP-9, Ang-1 and Ang-2, VEGF, EPO and TGFβ1 concentrations were measured from 69 patients with Type 1 or 2 diabetes and 40 controls.

RESULTS

Comparison of eyes with DR with controls revealed that the mean vitreous concentrations of proMMP-2 (p = 0.0015), totalMMP-2 (p = 0.0011), proMMP-9 (p = 0.00001), totalMMP-9 (p < 0.00001), Ang-2 (p < 0.00001), VEGF (p < 0.00001), EPO (p < 0.00001) and totalTGFβ1 (p = 0.000026) were significantly higher in the former group. A multivariate logistic regression analysis suggested intravitreal Ang-2 concentration being the key marker of PDR (p = 0.00025) (OR = 1507.9).

CONCLUSION

The main new finding is that the intravitreal concentrations of Ang-2 correlated significantly with MMP-9, VEGF, EPO and TGFβ1 levels in diabetic eyes undergoing vitrectomy. Thus, these factors could promote retinal angiogenesis synergistically.

Cytokine marker measurement in human neuroblastoma cells with supersensitive and multiplex assay: MUSTag technology

BACKGROUND

Recently, various sets of protein -biomarkers have been discovered in important diseases such as cancers, brain stroke and heart attack. However, clinical validation is difficult and time-consuming by individual assays or because of very low concentrations at early stages of the diseases. We have developed assay technology through an innovative modification of the immuno-PCR method for the super-sensitive and multiplex detection of target biomarkers.

METHODS

In the assay technology, each different oligo-tag simultaneously detects multiplex protein targets with extremely high-level sensitivity in a dose-dependent manner by qRT-PCR (maximum: three plexes). In this study, we measured specific secreted protein concentrations in the culture supernatant of a 24-h culture of transfected SH-SY5Y cells with MUSTag.

RESULTS

There was a significant increase in the protein level of tumor necrosis factor (TNF)-α measured with extremely high-level sensitivity (≥10 pg/mL). Compared with negative controls, the levels of TNF-α increased from 16.9 to 28.1 pg/mL (p = 0.011).

CONCLUSION

We suggest that our assay technology might be of clinical value in treating patients with cancer, cerebral ischemia, or patients who need a prompt and predictive diagnosis for adequate treatment.

Recombinant human sonic hedgehog protein regulates the expression of ZO-1 and occludin by activating angiopoietin-1 in stroke damage

This study examines the regulating effect of Sonic Hedgehog (Shh) on the permeability of the blood-brain barrier (BBB) in cerebral ischemia. By employing permanent middle cerebral artery occlusion (pMCAO) model, we find that Shh significantly decreases brain edema and preserves BBB permeability. Moreover, Shh increases zonula occludens-1 (ZO-1), occludin and angiopiotetin-1 (Ang-1) expression in the ischemic penumbra. Blockage of Shh with cyclopamine abolishes the effects of Shh on brain edema, BBB permeability and ZO-1, occludin, Ang-1 expression. Primary brain microvessel endothelial cells (BMECs) and astrocytes were pre-treated with Shh, cyclopamine, Ang-1-neutralizing antibody, and subjected to oxygen-glucose deprivation (OGD). Results show that the Ang-1 protein level in the culture medium of Shh-treated astrocytes is significantly higher. Shh also increased ZO-1, occludin and Ang-1 expression in BMECs, while cyclopamine and Ang-1-neutralizing antibody inhibited the effects of Shh on the ZO-1 and occludin expression, respectively. This study suggests that, under ischemic insults, Shh triggers Ang-1 production predominantly in astrocytes, and the secreted Ang-1 acts on BMECs, thereby upregulating ZO-1 and occludin to repair the tight junction and ameliorate the brain edema and BBB leakage.

Differential expression of capillary VEGF isoforms following traumatic brain injury

OBJECTIVES

While it is known that angiogenesis occurs after trauma, we sought to characterize the expression of vascular endothelial growth factor (VEGF) subtypes, vascular endothelial growth factor receptor 2 (VEGFR2) and angiopoietin within capillaries of animals subjected to traumatic brain injury (TBI). Further, we sought to characterize pericyte cell death in isolated capillaries.

METHODS

We used Marmarou's acceleration impact model to induce head trauma and measured VEGF, VEGFR2 and angiopoietin levels in isolated capillaries. TUNEL was used to determine pericyte cell death.

RESULTS

The VEGF response was restricted to the VEGF120 isoform. No increase in transcripts for VEGF164 and VEGF188 was observed. VEGFR2 was marginally increased and angiopoietin was increased. A subset of pericytes were TUNEL-positive.

DISCUSSION

These results show a distinct expression pattern of angiogenic factors following injury and suggest that pericyte involvement in adaptive angiogenesis may be altered following TBI.

Angiopoietin-1 elicits pro-inflammatory responses in monocytes and differentiating macrophages

The angiopoietin/Tie2 system is an important regulator of angiogenesis and inflammation. In addition to its functions in endothelial cells, Tie2 expression on non-endothelial cells allows for angiopoietin ligands to stimulate the cells. Although Ang1 is a strong Tie2 receptor agonist, little is known regarding the effect of Ang1 on non-endothelial cells, such as monocytes and macrophages. In this study, we found that Ang1 functionally binds to and stimulates monocytes via p38 and Erk1/2 phosphorylation. Ang1-mediated monocyte stimulation is associated with proinflammatory cytokine TNF-α expression. We also determined that Ang1 switched macrophage differentiation toward a pro-inflammatory phenotype, even in the presence of an anti-inflammatory mediator. These findings suggest that Ang1 plays a role in stimulating pro-inflammatory responses and could provide a new strategy by which to manage inflammatory responses.

COMP-angiopoietin-1 promotes cavernous angiogenesis in a type 2 diabetic rat model

Cartilage oligomeric matrix protein-angiopoietin-1 (COMP-Ang1) is an angiogenic factor for vascular angiogenesis. The aim was to investigate the effect of an intracavernosal injection of COMP-Ang1 on cavernosal angiogenesis in a diabetic rat model. Male Otsuka Long-Evans Tokushima Fatty (OLETF) rats made up the experimental group (1 yr old) and Long-Evans Tokushima Otsuka (LETO) rats made up the control group. The experimental group was divided into vehicle only, 10 µg COMP-Ang1, and 20 µg COMP-Ang1. COMP-Ang1 was injected into the corpus cavernosum of the penis. After 4 weeks, the penile tissues of the rats were obtained for immunohistochemistry and Western blot analysis. The immunoreactivity of PECAM-1 and VEGF was increased in the COMP-Ang1 group compared with the vehicle only group. Moreover, the expression of PECAM-1 and VEGF was notably augmented in the 20 µg Comp Ang-1 group. In the immunoblotting study, the expression of PECAM-1 and VEGF protein was significantly less in the OLEFT rats than in the control LETO rats. However, this expression was restored to control level after intracavernosal injection of COMP-Ang1. These results show that an intracavernosal injection of COMP-Ang1 enhances cavernous angiogenesis by structurally reinforcing the cavernosal endothelium.

Vascular endothelial growth factor-angiopoietin chimera with improved properties for therapeutic angiogenesis

BACKGROUND

There is an unmet need for proangiogenic therapeutic molecules for the treatment of tissue ischemia in cardiovascular diseases. However, major inducers of angiogenesis such as vascular endothelial growth factor (VEGF/VEGF-A) have side effects that limit their therapeutic utility in vivo, especially at high concentrations. Angiopoietin-1 has been considered to be a blood vessel stabilization factor that can inhibit the intrinsic property of VEGF to promote vessel leakiness. In this study, we have designed and tested the angiogenic properties of chimeric molecules consisting of receptor-binding parts of VEGF and angiopoietin-1. We aimed at combining the activities of both factors into 1 molecule for easy delivery and expression in target tissues.

METHODS AND RESULTS

The VEGF-angiopoietin-1 (VA1) chimeric protein bound to both VEGF receptor-2 and Tie2 and induced the activation of both receptors. Detailed analysis of VA1 versus VEGF revealed differences in the kinetics of VEGF receptor-2 activation and endocytosis, downstream kinase activation, and VE-cadherin internalization. The delivery of a VA1 transgene into mouse skeletal muscle led to increased blood flow and enhanced angiogenesis. VA1 was also very efficient in rescuing ischemic limb perfusion. However, VA1 induced less plasma protein leakage and myeloid inflammatory cell recruitment than VEGF. Furthermore, angioma-like structures associated with VEGF expression were not observed with VA1.

CONCLUSIONS

The VEGF-angiopoietin-1 chimera is a potent angiogenic factor that triggers a novel mode of VEGF receptor-2 activation, promoting less vessel leakiness, less tissue inflammation, and better perfusion in ischemic muscle than VEGF. These properties of VA1 make it an attractive therapeutic tool.

Endovascular cooling and endothelial activation in hemorrhagic stroke patients

BACKGROUND

Little is known about endothelial activation under the influence of endovascular temperature management. This analysis was designed to measure the endothelial markers Angiopoietin-1 (Ang-1) and -2 (Ang-2) in endovascularly based prophylactic normothermia versus conventional temperature management.

METHODS

In this randomized controlled trial patients with spontaneous subarachnoid or spontaneous intracerebral hemorrhage were prospectively enrolled and randomized in two treatment arms: (a) prophylactic normothermia group with target core temperature 36.5°C using endovascular cooling, (b) active control group with conventional stepwise predefined fever management using antipyretic medication and surface cooling. Blood samples were obtained on days 1, 4, and 7. In a substudy Ang-1 and -2 were measured in 63 patients for whom samples on consecutive days were available.

RESULTS

The median total fever burden during the course of treatment was 0.0°C and 5.9°C h in the endovascular and the conventional group, respectively (P < 0.0001). Angiopoietin serum levels did not yield a statistical difference when comparing the two treatment arms. Ang-1 was significantly lowered, whereas Ang-2 levels were significantly elevated on day 4 compared to baseline levels irrespective of group allocation (P < 0.0001). The application of non-steroidal anti-inflammatory drugs (NSAIDs) was associated with significantly increased Ang-1 (P < 0.05) and lower Ang-2 levels on day 7 (P < 0.05).

CONCLUSIONS

Endovascular long-term temperature management did not alter Ang-1 and -2 levels compared to the control group indicating that the endovascular cooling technique itself does not lead to additional endothelial impairment. However, application of NSAIDs led to lower Ang-2 serum concentrations in the endovascular group.

Involvement of the ANGPTs/Tie-2 system in ovarian hyperstimulation syndrome (OHSS)

Ovarian hyperstimulation syndrome (OHSS) is a disorder associated with ovarian stimulation. OHSS features are ovarian enlargement with fluid shifting to the third space. Disturbances in the vasculature are considered the main changes that lead to OHSS. Our aim was to analyze the levels of angiopoietins 1 and 2 (ANGPT1 and 2) and their soluble and membrane receptors (s/mTie-2) in follicular fluid (FF) and in granulosa-lutein cells culture (GLCs) from women at risk of developing OHSS. We also evaluated the effect of ANGPT1 on endothelial cell migration. In ovaries from an OHSS rat model, we analyzed the protein concentration of ANGPTs, their mTie-2 receptor, and platelet-derived growth factor PDGF-B, -D and PDGFR-β. ANGPT1 levels were increased in both FF and GLCs from women at risk of OHSS. Incubation of these FF with an ANGPT1 neutralizing antibody decreased endothelial cell migration. In the ovaries of OHSS rat model, mTie-2 protein levels increased and PDGF-B and -D decreased. In summary, these results suggest that ANGPT1 could be another mediator in the development of OHSS.

Angiogenic axis angiopoietin-1 and angiopoietin-2/Tie-2 in non-small cell lung cancer: a bronchoalveolar lavage and serum study

Angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2), ligands for the Tie-2 receptor expressed on endothelial cells, play a critical role in angiogenesis, in concert with vascular endothelial growth factor (VEGF). Angiogenesis is important for tumor growth and development and also is implicated in the pathogenesis of interstitial lung diseases. The aim of this study was to evaluate the concentration of Ang-1, Ang-2, Tie-2, interleukin-18 (IL-18), transforming growth factor beta-1 (TGF β1), and VEGF domain in both serum and bronchoalveolar lavage fluid (BALF) of lung cancer patients before chemotherapy. We studied 45 non-small cell lung cancer (NSCLC) patients (M/F; 38/7; mean age 62 ± 4 years). The age-matched control groups consisted of 15 sarcoidosis (BBS), 15 hypersensivity pneumonitis (HP), and 15 healthy subjects. The patients with NSCLC had a significantly higher level of Ang-1 compared with the BBS and healthy subjects, and a higher level of Ang-2 compared with the healthy subjects in both serum and BALF. BALF level of IL-18 was lower in the NSCLC than that in the HP group, but higher than that in the BBS patients. Serum level of IL-18 was higher in the NSCLC than in the healthy subjects. The NSCLC group had lower VEGF in BALF than that in healthy subjects. Receiver-operating characteristics (ROC) curves were applied to find the cut-off the serum levels of Ang-1 and Ang-2 levels in BALF. We did not find any correlation between the levels of Ang-1, Ang-2, Tie-2, and the stage of tumor or treatment response (prospectively). We conclude that the angiogenic axis Ang-1 and Ang-2/Tie-2 may play an important role in lung cancer development and their concentrations may be a useful marker at the time of initial diagnosis of lung cancer.

VEGF and angiopoietins in diabetic glomerulopathy: how far for a new treatment?

Diabetic nephropathy (DN) is the major cause of end-stage renal disease in Western countries and its prevalence continues to increase (United States Renal Data System 2010, http://www.usrds.org/). Treatments currently utilised for DN provide only partial renoprotection, hence the need to identify new targets for therapeutic intervention. Metabolic and haemodynamic abnormalities have been implicated in the pathogenesis of DN, triggering the activation of intracellular signaling molecules that lead to the dysregulation of vascular growth factors and cytokines, such as vascular endothelial growth factor (VEGF) and angiopoietins, important players in the functional and structural regulation of the glomerular filtration barrier. This review focuses on the importance of VEGF-A and angiopoietins in kidney physiology and in the diabetic kidney, exploring their potential therapeutic role in the prevention and delay of diabetic glomerulopathy.