The arrhythmogenic effect of self-assembling nanopeptide hydrogel scaffolds on neonatal mouse cardiomyocytes.

The chaotic spatial disarray due to extracellular matrix expansion disrupts cardiomyocytes interaction and causes arrhythmia. We hypothesized that disordered nanopeptide scaffolds can mimic the chaotic spatial disarray related to cardiac fibrosis and have arrhythmogenic effects on cardiomyocytes. Primary mouse cardiomyocytes were cultured in 2D traditional and 3D nanopeptide hydrogel scaffold systems. Cardiomyocytes in 3D scaffolds showed irregular spontaneous contractile activity as compared with 2D culture controls. Calcium fluorimetric imaging revealed that basal intracellular calcium level increased 1.42-fold in cardiomyocytes cultured in the 3D scaffold, in vitro. The mRNA levels of sarcoplasmic reticulum calcium transport ATPase, ryanodine 2 receptor and connexin 43 elevated 2.14-fold, 2.33-fold and 2.62-fold in 3D compared with 2D. Immunofluorescence imaging revealed lateralization of the distribution of connexin 43 in 3D group. These findings suggest that 3D hydrogel culture system provides a model for the development of cardiac dysrhythmia. These limitations should be considered during cardiac tissue engineering. FROM THE CLINICAL EDITOR: This team of scientists has established a unique 3D hydrogel culture system as a model for the development of cardiac dysrhythmia.

Enhancement of an electroporation system for gene delivery using electrophoresis with a planar electrode.

In this paper a new electroporation (EP) system is developed, which includes an EP microchip and a logic circuit, which combined with electrophoresis (ES), can provide site-specific enhancement of gene concentration. In this ES-EP microchip, an arc planar electrode provides the ES function for DNA attraction, and interdigitated array electrodes provide appropriate electric fields for the EP on the chip surface. In addition, the adherent cells can be manipulated in situ without detachment of the ES-EP microchip, which performs the "Lab on a chip". Experimental results have shown that the efficiency of gene transfection with an attracting-electric field (35.89%) becomes much higher than that without an attracting-electric field (16.62%). Cell numbers as low as 10(4) cells, and DNA as little as 4 microg are sufficient for evaluating the phenotypic effects following the over-expression of the introduced genes on the ES-EP microchip. The proposed system has the advantages of portability, cost-effectiveness, a high transfection rate and ease of operation.