15-hydroxy-11-alpha-9-alpha-(epoxymethano)prosta-5-13-dienoic-acid and Ischemia

We have shown that the differentiation of human-induced pluripotent stem cells (hiPSCs) into endothelial cells (ECs) is more efficient when performed with a 3-dimensional (3D) scaffold of biomaterial than in monolayers. The current study aims to further increase hiPSC-EC differentiation efficiency by deciphering the signaling pathways in 3D scaffolds.. We modified our 3D protocol by using U-46619 to upregulate both p38 mitogen-activated protein kinase (p38MAPK) and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling, which increased the differentiation efficiency (as measured by CD31 expression) to as high as 89% in two established hiPSC lines. The differentiated cells expressed arteriovenous, but not lymphatic, markers; formed tubular structures and EC lumen in vitro; had significantly shorter population-doubling times than monolayer-differentiated hiPSC-ECs; and restored perfusion and vascularity in a murine hind limb ischemia model. The differentiation efficiency was also > 85% in three hiPSC lines that had been derived from patients with diseases or disease symptoms that have been linked to endothelial dysfunction.. These observations demonstrate that activating both p38MAPK and ERK1/2 signaling pathways with U-46619 improves the efficiency of arteriovenous hiPSC-EC differentiation and produces cells with greater proliferative capacity.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Cell Differentiation; Cell Line; Disease Models, Animal; Endothelial Cells; Enzyme Activation; Hindlimb; Humans; Induced Pluripotent Stem Cells; Ischemia; MAP Kinase Signaling System; Mesoderm; Mice, Inbred NOD; Mice, SCID; p38 Mitogen-Activated Protein Kinases; Perfusion; Pyridines; Pyrimidines

The tripeptide ZAMI-420 has been shown by Gervasi et al. (4) to be able to prevent experimentally-induced gastric damage, possibly by interfering with the synthesis and the action of thromboxane A2 (TXA2), a potent vasoconstrictor and platelet aggregator. Further studies on a canine stomach wedge preparation, supplied with a fixed flow of 10 ml/min-1 of arterial blood from the same dog have been designed to investigate this hypothesis. Bolus injection of arachidonic acid (AA) through a 30-sec incubation coil that allows the production of TXA2 resulted in a dose-related increase in resistance to flow in the stomach wedge vasculature and blanching of the gastric mucosa. This was progressively inhibited by ZAMI-420 perfused through the delay coil. Similar results were obtained with 1-benzylimidazole (BI). ZAMI-420, but not BI, produced a partial inhibition of TXA2-induced vasoconstriction when infused close to the stomach. Investigations of the antagonistic action of ZAMI-420 on the pharmacological effect of the formed TXA2 were carried out using strips of celiac and mesenteric artery from rabbits and gastric artery from dogs. Preincubation of these vascular preparations with ZAMI-420 led to progressive inhibition of the contraction induced either by the stable endoperoxide U-46619 or by CaCl2. Whittle et al. (3) reported that TXA2 may be involved in the pathogenesis of ulcerative disorders of the stomach; if so, both the inhibition of the synthesis and the antagonism of TXA2-induced effects could be of value in the prevention of experimentally-induced gastric disorders.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Celiac Artery; Dogs; Female; Gastric Mucosa; Ischemia; Male; Mesenteric Arteries; Oligopeptides; Prostaglandin Endoperoxides, Synthetic; Rabbits; Stomach; Thromboxane A2; Thromboxanes; Vasoconstriction

Prostaglandin (PG) precursors can be converted into many related substances with diverse biological activities. Products formed from arachidonate include thromboxane A2, which is a potent platelet aggregator and vasoconstrictor. Mucosa and muscle from human stomach, ileum and colon yield substantial amounts of this substance, and thromboxane A2 is also formed in the alimentary tract of other species. Injection of arachidonic acid or a stable thromboxane A2-mimetic (U-46619) into the arterial blood supplying dog stomach causes mucosal ischaemia. The ensuing necrosis that occurs with arachidonic acid when the mucosa is bathed with HCl and taurocholic acid can be prevented by a thromboxane synthetase inhibitor. Isolated gastrointestinal muscle contracts to low amounts of the thromboxane A2-mimetic U-46619, some human tissues being sensitive to less than 1pg/ml. These findings constitute a rational basis for examining thromboxane synthetase inhibitors in peptic ulceration and smooth muscle spasm. Unlike cyclo-oxygenase inhibitors, thromboxane synthetase inhibitors spare, or even increase, the formation of prostanoids with actions opposite to those of thromboxane A2.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Animals; Arachidonic Acids; Digestive System; Gastric Mucosa; Humans; Ischemia; Muscle, Smooth; Prostaglandin Endoperoxides; Prostaglandin Endoperoxides, Synthetic; Thromboxane A2; Thromboxane-A Synthase; Thromboxanes