Platelet microvesicles promote the recovery of neurological function in mouse model of cerebral infarction by inducing angiogenesis

The aim of this study is to investigate the effect of PMVs on mice with ischemic cerebral infarction and its mechanism. Male C57BL/6 mice were selected, and the right focal cortical infarction model was established via cauterization under a microscope and randomly divided into sham operation (Sham) group, normal saline control (Saline) group and platelet microvesicles intervention (PMVs) group. At 1 h after modeling, 5 μL of PMVs (50 μg/mL) or normal saline was injected into the lateral ventricle. The neurological function of mice in each group was evaluated at 1, 3, 7, 14 and 28 d after modeling. After 28 d, the cerebral infarction area was detected via 2,3,5-triphenyltetrazolium chloride (TTC) staining. At 7 and 28 d after modeling, the blood vessel density, proliferation rate of new vessels and encapsulation rate of pericytes were detected via immunofluorescence staining. Moreover, the changes in cerebral cortical blood flow at the infarction side were detected before modeling and at 7 and 28 d after modeling, respectively. Finally, the expressions of proangiogenic factors vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1) and N-Cadherin were detected via Western blotting at 3, 7 and 28 d after modeling. PMVs could promote the improvement of neurological function and significantly reduce the cerebral infarction volume in mice with cerebral infarction. PMVs promoted proliferation of new vessels and increased blood vessel density at the infarction edge in mice with cerebral infarction. PMVs could increase the encapsulation rate of pericytes at the infarction edge and improve the permeability of blood-brain barrier in mice with cerebral infarction. PMVs could increase the cerebral cortical blood flow perfusion in mice with cerebral infarction. PMVs could increase proangiogenic factors in brain tissues in mice with cerebral infarction. PMVs could significantly improve the recovery of neurological function in mice with cerebral infarction, which is closely related to the ability of PMVs to promote angiogenesis at the infarction edge. The possible mechanism is that PMVs facilitate angiogenesis after cerebral infarction through promoting the expressions of VEGF, Ang-1 and N-Cadherin. More importantly, the new vessels promoted by PMVs have complete structure and perfect function, and can improve the cerebral blood flow perfusion at the infarction side.

Alginate-Chitosan Hydrogels Provide a Sustained Gradient of Sphingosine-1-Phosphate for Therapeutic Angiogenesis

Sphingosine-1-phosphate (S1P), a bioactive lipid, is a potent candidate for treatment of ischemic vascular disease. However, designing biomaterial systems for the controlled release of S1P to achieve therapeutic angiogenesis presents both biological and engineering challenges. Thus, the objective of this study was to design a hydrogel system that provides controlled and sustained release of S1P to establish local concentration gradients that promote neovascularization. Alginate hydrogels have been extensively studied and characterized for delivery of proangiogenic factors. We sought to explore if chitosan (0, 0.1, 0.5, or 1%) incorporation could be used as a means to control S1P release from alginate hydrogels. With increasing chitosan incorporation, hydrogels exhibited significantly denser pore structure and stiffer material properties. While 0.1 and 0.5% chitosan gels demonstrated slower respective release of S1P, release from 1% chitosan gels was similar to alginate gels alone. Furthermore, 0.5% chitosan gels induced greater sprouting and directed migration of outgrowth endothelial cells (OECs) in response to released S1P under hypoxia in vitro. Overall, this report presents a platform for a novel alginate-chitosan hydrogel of controlled composition and in situ gelation properties that can be used to control lipid release for therapeutic applications.

Classical and non-classical proangiogenic factors as a target of antiangiogenic therapy in tumor microenvironment

Angiogenesis is sustained by classical and non-classical proangiogenic factors (PFs) acting in tumor microenvironment and these factors are also potential targets of antiangiogenic therapies. All PFs induce the overexpression of several signaling pathways that lead to migration and proliferation of endothelial cells contributing to tumor angiogenesis and survival of cancer cells. In this review, we have analyzed each PF with its specific receptor/s and we have summarized the available antiangiogenic drugs (e.g. monoclonal antibodies) targeting these PFs, some of these agents have already been approved, others are currently in development for the treatment of several human malignancies.