Changes of the Collagen composition in the heart caused by microcurrent application. An explanation for the improvement of cardiac function by bi-ventricular pacing?

Abstract

Objective Improvement of cardiac function by the unloading effect of a cardiac assist device mainly depends on the duration of heart failure (HF). Patients with a short history of HF ( 5 years) do not show significant cardiac function improvement is that the collagen composition of the extracellular matrix is irreversible. It is successful clinical practice to apply microcurrent in patients with bone fractures and wound healing disturbances in order to improve the healing process by modulation of the collagen synthesis. In order to examine whether microcurrent can also influence the collagen synthesis in the myocardium, the effect of microcurrent application on collagen synthesis of adult cardiomyocytes was investigated. Methods Adult cardiomyocytes were isolated and cultivated in 24 well cell culture plates. Current of different magnitudes (0, 20, 40, 60, 80, 100 :A) was applied via platinum electrodes by a special custom-made device. The whole equipment was incubated under cell culture conditions (+37°C, 5% CO2) over a period of 7 days. Changes of the collagen type I and type III synthesis were analyzed using immunohistochemical staining methods. Collagen type I and type III content was quantified using a special fluorescence confocal laser scanning microscopy system including special analysis software. Results Compared to cardiomyocytes exposed to 0 :A (control cells), collagen type I synthesis of cardiomyocytes showed no significant change after exposure to a moderate current magnitude(40, 60 :A) but a highly significant mean decrease (20.6 %) if exposed to high current (80, 100 :A). Collagen type III revealed a mean increase at moderate current of 29.7 % and a decrease of 25.2 % at high current exposure. As a side effect, we detected an increase in the cell proliferation rate at moderate and high current. Conclusion The results obtained in cell culture suggest that the application of micro-current is able to modulate the synthesis of collagen. In particular, in dependency of the current magnitude collagen type I can be up- or down-regulated. Collagen type I is responsible for the stiffness and the degree of dilatation of the heart. Therefore it can be envisaged that this method -if applied clinically - may help to improve cardiac function, as it helps to heal bone fractures.