In vitro Assessment, Cellular Uptake and Anti-cardiomyocyte Apoptosis of Tetramethylpyrazine PEG-PE Micelles

OBJECTIVE To prepare tetramethylpyrazine PEG-PE(TMP-PEG-PE) micelles, and to evaluate the cellular uptake and anti-cardiomyocyte apoptosis of the nanomicelle. METHODS TMP-PEG-PE micelles were prepared by thin film hydration method and characterized. The drug delivery system was evaluated by in vitro release, cell uptake and apoptosis assays. RESULTS The particle size of TMP-PEG-PE micelles was (15.8±0.9)nm, the zeta potential was -(20.5±0.4)mV, the drug loading was (5.7±0.3)% and the encapsulation efficiency was (87.2±5.4)%. The results of electron microscopy showed that the TMP-PEG-PE micelles were in the shape of a regular spherical structure. The critical micelle concentration of PEG-PE micelles was determined by Pyrene assay to be about 5.3 μg·mL^-1. The results of cell uptake assay showed that PEG-PE nanomicelles could enhance the cellular uptake of the drug and reduce the extracellular residual amount. TMP-PEG-PE micelles had good stability in 10% fetal bovine serum DMEM medium. Isoproterenol was used to induce myocardial apoptosis, Hoechst staining indicated that there were a lot of morphological changes in apoptotic cardiomyocytes. TMP-PEG-PE micelles could significantly reduce the pro-apoptotic caspase-3 activity, inhibit the expression of the pro-apoptotic protein Bax, and increase the expression of anti-apoptotic protein Bcl-2, which were significantly better than the test results of TMP(P<0.01). CONCLUSION TMP-PEG-PE micelles have the advantages of small particle size, high drug loading and slow drug release, which can greatly improve the myocardial cell uptake of TMP and enhance its anti-cardiomyocyte apoptosis effect.