COMP-Ang1 Potentiates EPC Treatment of Ischemic Brain Injury by Enhancing Angiogenesis Through Activating AKT-mTOR Pathway and Promoting Vascular Migration Through Activating Tie2-FAK Pathway

Successful recovery from brain ischemia is limited due to poor vascularization surrounding the ischemic zone. Cell therapy with strong angiogenic factors could be an effective strategy to rescue the ischemic brain. We investigated whether cartilage oligomeric matrix protein (COMP)-Ang1, a soluble, stable and potent Ang1 variant, enhances the angiogenesis of human cord blood derived endothelial progenitor cells (hCB-EPCs) for rescuing brain from ischemic injury. COMP-Ang1 markedly improved the tube formation of capillaries by EPCs and incorporation of EPCs into tube formation with human umbilical vein endothelial cells (HUVECs) upon incubation on matrigel in vitro. COMP-Ang1 stimulated the migration of EPCs more than HUVECs in a scratch wound migration assay. The transplanted EPCs and COMP-Ang1 were incorporated into the blood vessels and decreased the infarct volume in the rat ischemic brain. Molecular studies revealed that COMP-Ang1 induced an interaction between Tie2 and FAK, but AKT was separated from the Tie2-FAK-AKT complex in the EPC plasma membrane. Tie2-FAK increased pp38, pSAPK/JNK, and pERK-mediated MAPK activation and interacted with integrins alphanubeta3, alpha4, beta1, finally leading to migration of EPCs. AKT recruited mTOR, SDF-1, and HIF-1alpha to induce angiogenesis. Taken together, it is concluded that COMP-Ang1 potentiates the angiogenesis of EPCs and enhances the vascular morphogenesis indicating that combination of EPCs with COMP-Ang1 may be a potentially effective regimen for ischemic brain injury salvage therapy.

Radiography evaluation of enhanced vascularization of COMP-Ang-1 on acellular nerve / 中华显微外科杂志

Objective To observe the way of vascularization of acellular nerves and evaluate the enhanced vascularization of using COMP-Ang-1 into acellular nerve on bridging sciatic nerve gaps by radiography.Methods From March,2013 to June,2014,acellular nerves were harvested by chemical extraction.Thirty-six female rats weighing 200-250 g were randomly divided into 2 groups:18 animals with 1 cm long sciatic nerve lesions were repaired by nerve grafting (control group),18 animals with 1 cm long sciatic nerve lesions were repaired by nerve grafting and COMP-Ang-1 were administrated after surgery.Grafts were harvested after perfusion of lead oxide (carotid artery) on day 7,day 14 and day 21 postoperatively.Radiography was performed to capture the two dimensional image.The rules of vascularization of acellular nerve and the enhanced effects of COMP-Ang-1 on vascularization were evaluated.Results The density of vessels in COMP-Ang-1 group were higher than control group after 7 days (2701.60 ± 318.93 vs.925.40 ± 106.22,P =0.030),14 days (3309.21 ± 381.31 vs.2832.70 ± 189.23,P =0.210) and 21 days (4787.33 ± 251.09 vs.3469.36 ± 232.10,P =0.030) postoperatively; the area of vessels in COMP-Ang-1 group were higher than control group after 7 days (9231.03 ± 581.91 μm2 vs.4839.01 ± 101.01 μm2,P =0.043) and 14 days (15561.13 ± 697.73 vs.6811.07 ± 250.05,P =0.049) postoperatively.Conclusion COMP-Ang-1 can enhance the vascularization of acellular nerves fairly.

COMP-Angiopoietin-1 Stimulates Synovial Proliferation but Suppresses Osteoclast by Enhancing Angiogenesis and Osteoblast Maturation in Collagen-Induced Arthritis

OBJECTIVE: Angiopoietin-1 (Ang1) is a potent angiogenic factor that can increase synovial angiogenesis and also enhance osteoblast maturation and bone formation. However, its role in rheumatoid arthritis (RA) has not been well documented. Thus, we investigated roles of Ang1 in collagen-induced arthritis (CIA). METHODS: A recombinant adenovirus carrying the gene that encodes either cartilage oligomeric matrix protein (AdCOMP)-Ang1 (a modified form of Ang1) or LacZ (AdLacZ) was injected intravenously into CIA mice. Clinical, radiological, histopathological, and immunofluorescent analyses were performed. Serum levels of receptor activators of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG) and expression of osteoblast maturation genes were analyzed. RESULTS: AdCOMP-Ang1-injected mice developed more severe inflammation than the AdLacZ-injected mice. However, there were no significant differences in cartilage damage and bone erosion. More PECAM-1-positive blood vessels were seen in the synovium of the AdCOMP-Ang1-injected mice than in those injected with AdLacZ. Interestingly, a lower number of TRAP-positive osteoclasts were observed in AdCOMP-Ang1-injected CIA mice than in the AdLacZ group when comparing sections obtained from joints showing similar synovial proliferation. The serum OPG/RANKL ratio and expression of osteoblast maturation genes, such as runt-related transcription factor 2, bone sialoprotein, type 1 collagen, osteopontin, and osterix, were significantly upregulated in the AdCOMP-Ang1 group. CONCLUSION: COMP-Ang1 facilitates arthritis onset and increases synovial inflammation, but enhances osteoblast maturation, which in turn inhibits osteoclastogenesis by increasing the OPG/RANKL ratio in CIA. Our results suggest that careful investigation is necessary to delineate the possible therapeutic use of COMP-Ang1 as an adjunctive agent, in combination with anti-inflammatory therapies, for the prevention of bone destruction in RA.

Angiopoietin-1 variant, COMP-Ang1 attenuates hydrogen peroxide-induced acute lung injury

Reactive oxygen species (ROS) play a crucial role in acute lung injury. Tissue inflammation, the increased vascular permeability, and plasma exudation are cardinal features of acute lung injury. Angiopoietin-1 (Ang1) has potential therapeutic applications in preventing vascular leakage and also has beneficial effects in several inflammatory disorders. Recently developed COMP-Ang1 is more potent than native Ang1 in phosphorylating tyrosine kinase with immunoglobulin and EGF homology domain 2 receptor in endothelial cells. However, there are no data on effects and related molecular mechanisms of COMP- Ang1 on ROS-induced acute lung injury. We used hydrogen peroxide (H2O2)-inhaled mice to evaluate the effect of COMP-Ang1 on pulmonary inflammation, bronchial hyper-responsiveness, and vascular leakage in acute lung injury. The results have revealed that VEGF expression, the levels of IL-4, TNF-alpha, IL-1 beta, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 in lungs, the levels of hypoxia-inducible factor-1alpha (HIF-1 alpha) and NF-kappa B in nuclear protein extracts, phosphorylation of Akt, and vascular permeability were increased after inhalation of H2O2 and that the administration of COMP-Ang1 markedly reduced airway hyper-responsiveness, pulmonary inflammation, plasma extravasation, and the increases of cytokines, adhesion molecules, and VEGF in lungs treated with H2O2. We have also found that the activation of HIF-1a and NF-kappa B and the increase of phosphoinositide 3-kinase activity in lung tissues after H2O2 inhalation were decreased by the administration of COMP-Ang1. These results suggest that COMP-Ang1 ameliorates ROS-induced acute lung injury through attenuating vascular leakage and modulating inflammatory mediators.