Study Of The Protective Effects Of Modified PGE₂ On Hypoxia Injury In Cardiomyocytes Of Diabetes Mellitus

Objetive: In this study, cobalt chloride induced cardiomyocte hypoxia injury was as a cell model, investigates the protective effect of polyethylene glycol?PEG? modified prostaglandin E₂?PGE₂? to this model and the myocardial targeting effect, and then to explore its mechanism. Methods: First of all, PEG and PGE₂ synthesis under certain conditions, and assisted laser desorption ionization time of flight mass spectrometry?MALDI-TOF? and infrared spectroscopy?FT-IR? detecting the successful synthesis of the polymer, followed by dynamic light scattering?DLS? and transmission electron microscopy?TEM? observation of the polymer particle size, dispersion and morphology. We tested the biocompatibility of the polymer, hemolytic and its effect on myocardial hypoxia model of cell viability, cell morphology, apoptosis and the expression of apoptosis related proteins. Then we use confocal laser scanning microscope?CLSM? to observing myocardial targeting effect of the polymer, and competitive inhibition assay to verify the way of polymer into cells. Then we through an animal experiments conducted in rats pharmacokinetic experiment to test half-life of 4arm-PEG-PGE₂. Results: 1 The average molecular weight of 4arm-PEG-PGE₂ was 6175.682 detected by MALDI-TOF and FT-IR, and the infrared spectrum having characteristic peaks of amide linkage,and double bond, a carbonyl group, a methylene group of PGE₂ corresponding to the peak appeared, therefore, polymer 4arm-PEG-PGE₂ synthesis successfully. By DLS and TEM we could see the polymer dispersed spherical uniform, and the average particle size was 224.2±4.063 nm.2 Biocompatible polymers were tested and found NIH3T3 cells and H9c2 cell viability were greater than 80%, which proved the 4arm-PEG-PGE₂ has good biocompatibility. And the hemolytic test confirmed that the different concentration of polymer in the body were no hemolysis effect of red blood cell, indicating that 4arm-PEG-PGE₂ without toxic effects on the human body.3 We detected the influnce of the different concentration of the polymer to myocardial hypoxia model viability by MTT assay, was found that those were improved significantly. While the number of cells, shape and the shape of nuclei were improved as well. Cell apoptosis rate detected by flow cytometer was found significantly reduced, with 4arm-PEG-PGE₂ at a concertration of 125 ?g/mL and 250 ?g/mL. And the release of lactate dehydrogenase?LDH? and the expression of caspase-3 reduced significantly after the intervention.4 CLSM to observe the polymer of fluorescent tags in 3 h, 8 h, 24 h in H9c2 cells and NIH3T3 cell aggregation degree have significant differences, different time H9c2 cells within the green fluorescence intensity were significantly stronger than the NIH3T3 cells, instruction 4arm-PEG-PGE₂ on myocardial cell does have targeted. And by competitive inhibition test, we can see the PGE₂ can inhibit polymer into cells, shows that polymer is mediated by receptor cell function into cells.5 Through the rat in vivo pharmacokinetic experiment, we could confirm the half-life of PEG modified PGE₂ is greatly extended, which was 19.3±2.43 h. Conclusion: Polyethylene glycol?PEG? modified prostaglandin E₂ had stable chemical properties and good biocompatibility, which can improve H9c2 cell hypoxia model of cell viability, apoptosis rate and form significantly, also reduced the release of LDH and the expression of caspase-3 from molecular level. And 4arm-PEG-PGE₂ is targeted to myocardial cells, and its half-life is extended to 19.3±2.43 h, significantly improve the bioavailability. To sum up, polyethylene glycol modified prostaglandin E₂ mediated by EP4 receptors on the surface of the cardiomyocyte, and inhibition of myocardial cell apoptosis, thus protecting hypoxia injury of myocardial cells.