Neural stem cells (NSCs) play vital roles in brain homeostasis and exhibit a broad repertoire of potentially therapeutic actions following neurovascular injury. One such injury is stroke, a worldwide leading cause of death and disability. Clinically, extensive injury from ischemic stroke results from ischemia-reperfusion (IR), which is accompanied by inflammation, blood-brain barrier (BBB) damage, neural cell death, and extensive tissue loss. Tissue plasminogen activator (tPA) is still the only US Food and Drug Administration–approved clot-lysing agent. Whereas the thrombolytic role of tPA within the vasculature is beneficial, the effects of tPA (in a non-thrombolytic role) within the brain parenchyma have been reported as harmful. Thus, new therapies are needed to reduce the deleterious side effects of tPA and quickly facilitate vascular repair following stroke. The Stroke Treatment Academic Industry Roundtable (STAIR) recommends that stroke therapies “focus on drugs/devices/treatments with multiple mechanisms of action and that target multiple pathways”. Thus, based on multifactorial ischemic cascades in various stroke stages, effective stroke therapies need to focus on targeting and ameliorating early IR injury as well as facilitating angiogenesis, neurogenesis, and neurorestorative mechanisms following stroke. This review will discuss the preclinical perspectives of NSC transplantation as a promising treatment for neurovascular injury and will emphasize both the subacute and chronic phase of ischemic stroke.

IntroductionDiabetic retinopathy (DR) is the leading cause of blindness among the working population in the USA. Current therapies, including anti-vascular endothelial growth factor treatments, cannot completely reverse the visual defects induced by DR. MicroRNA-150 (miR-150) is a regulator that suppresses inflammation and pathological angiogenesis. In patients with diabetes, miR-150 is downregulated. As chronic inflammation is a major contributor to the pathogenesis of DR, whether diabetes-associated decrease of miR-150 is merely associated with the disease progression or decreased miR-150 causes retinal inflammation and pathological angiogenesis is still unknown.Research design and methodsWe used high-fat diet (HFD)-induced type 2 diabetes (T2D) in wild type (WT) and miR-150 knockout (miR-150-/-) mice for this study and compared retinal function and microvasculature morphology.ResultsWe found that WT mice fed with an HFD for only 1 month had a significant decrease of miR-150 in the blood and retina, and retinal light sensitivity also decreased. The miR-150-/- mice on the HFD developed diabetes similar to that of the WT. At 7–8 months old, miR-150-/- mice under normal diet had increased degeneration of retinal capillaries compared with WT mice, indicating that miR-150 is important in maintaining the structural integrity of retinal microvasculature. Deletion of miR-150 worsened HFD-induced retinal dysfunction as early as 1 month after the diet regimen, and it exacerbated HFD-induced T2DR by further increasing retinal inflammation and microvascular degeneration.ConclusionThese data suggest that decreased miR-150 caused by obesity or diabetic insults is not merely correlated to the disease progression, but it contributes to the retinal dysfunction and inflammation, as well as the development of DR.

BackgroundWe recently discovered a small endogenous peptide, peptide Lv, with the ability to activate vascular endothelial growth factor receptor 2 and its downstream signaling. As vascular endothelial growth factor through vascular endothelial growth factor receptor 2 contributes to normal development, vasodilation, angiogenesis, and pathogenesis of various diseases, we investigated the role of peptide Lv in vasodilation and developmental and pathological angiogenesis in this study.Methods and ResultsThe endothelial cell proliferation, migration, and 3‐dimensional sprouting assays were used to test the abilities of peptide Lv in angiogenesis in vitro. The chick chorioallantoic membranes and early postnatal mice were used to examine its impact on developmental angiogenesis. The oxygen‐induced retinopathy and laser‐induced choroidal neovascularization mouse models were used for in vivo pathological angiogenesis. The isolated porcine retinal and coronary arterioles were used for vasodilation assays. Peptide Lv elicited angiogenesis in vitro and in vivo. Peptide Lv and vascular endothelial growth factor acted synergistically in promoting endothelial cell proliferation. Peptide Lv–elicited vasodilation was not completely dependent on nitric oxide, indicating that peptide Lv had vascular endothelial growth factor receptor 2/nitric oxide–independent targets. An antibody against peptide Lv, anti‐Lv, dampened vascular endothelial growth factor–elicited endothelial proliferation and laser‐induced vascular leakage and choroidal neovascularization. While the pathological angiogenesis in mouse eyes with oxygen‐induced retinopathy was enhanced by exogenous peptide Lv, anti‐Lv dampened this process. Furthermore, deletion of peptide Lv in mice significantly decreased pathological neovascularization compared with their wild‐type littermates.ConclusionsThese results demonstrate that peptide Lv plays a significant role in pathological angiogenesis but may be less critical during development. Peptide Lv is involved in pathological angiogenesis through vascular endothelial growth factor receptor 2–dependent and –independent pathways. As anti‐Lv dampened the pathological angiogenesis in the eye, anti‐Lv may have a therapeutic potential to treat pathological angiogenesis.

Peptide Lv is a small endogenous secretory peptide that is expressed in various tissues and conserved across different species. Patients with diabetic retinopathy, an ocular disease with pathological angiogenesis, have upregulated peptide Lv in their retinas. The pro-angiogenic activity of peptide Lv is in part through promoting vascular endothelial cell (EC) proliferation, migration, and sprouting, but its molecular mechanism is not completely understood. This study aimed to decipher how peptide Lv promotes EC-dependent angiogenesis by using patch-clamp electrophysiological recordings, Western immunoblotting, quantitative PCR, and cell proliferation assays in cultured ECs. Endothelial cells treated with peptide Lv became significantly hyperpolarized, an essential step for EC activation. Treatment with peptide Lv augmented the expression and current densities of the intermediate-conductance calcium-dependent potassium (KCa3.1) channels that contribute to EC hyperpolarization but did not augment other potassium channels. Blocking KCa3.1 attenuated peptide Lv-elicited EC proliferation. These results indicate that peptide Lv-stimulated increases of functional KCa3.1 in ECs contributes to EC activation and EC-dependent angiogenesis.

Background: Peptide Lv is an endogenous secretory peptide that is upregulated in the eyes of patients with diabetic retinopathy, an ocular disease with pathological angiogenesis. Peptide Lv promotes vascular endothelial cell proliferation, migration, and sprouting, and blocking peptide Lv with a specific antibody, anti-Lv, dampens neovascularization, so peptide Lv is an angiogenic factor. However, the molecular mechanism of how peptide Lv promotes angiogenesis is not clear. We found that peptide Lv causes endothelial cell membrane hyperpolarization, a step that is essential in endothelium-dependent angiogenesis. Peptide Lv augments the protein expression and current densities of K Ca 3.1, an ion channel underlying the endothelial hyperpolarization. As ion channels require trafficking and insertion to the plasma membrane to be functional after they are expressed, we aimed to determine the downstream signaling of peptide Lv that is involved in the trafficking of K Ca 3.1 in endothelial cells. Hypothesis: Peptide Lv activates the MEK1/ERK signaling pathway to promote the trafficking and membrane insertion of K Ca 3.1 in endothelial cells. Blocking MEK1/ERK will prevent augmentation of K Ca 3.1 by peptide Lv. Methods: Cultured human umbilical vein endothelial cells (HUVECs) were treated with peptide Lv (500 ng/ml) or PBS (vehicle control) in the presence/absence of FR180402 (10 μM; an ERK inhibitor) or PD98059 (10 μM, a MEK1 inhibitor) followed by the patch-clamp electrophysiological recordings and biotinylation assays. Results: Blocking ERK activation attenuated the peptide Lv-meditated membrane hyperpolarization and increase of K Ca 3.1 currents in endothelial cells. Blocking ERK activation did not affect peptide Lv-elicited increases of K Ca 3.1 protein expression, but it reduced the level of membrane-bound K Ca 3.1 Conclusions: The MEK1/ERK signaling pathway mediates peptide Lv-elicited trafficking and membrane insertion of K Ca 3.1 but does not affect the increase of K Ca 3.1 expression by peptide Lv.