THE EFFECT OF EXOSOME-MEDIATED EMBRYONIC TRANSCRIPTION FACTOR TREATMENT ON CARDIAC MYOCYTE REPROGRAMMING IN RATS WITH CARDIAC ARREST

Zijing Guo^{1, 2, *}

¹Department of Pharmacology, Xiangnan University, Chenzhou, 423000, China - ²“Biomedical Microbiology Research” Key Laboratory of Universities in Hunan Province, Chenzhou, 423000, China

Objective: To analyze the effect of exosome-mediated embryonic transcription factor tbox18 on cardiomyocyte reprogramming in rats with myocardial block, in order to obtain the relevant mechanism of tbox18 on cardiomyocyte impulse coding. 

Methods: Neonatal rat ventricular myocytes (NRVMs) were infected with adenovirus carrying tbox18 and labeled with green fluorescence, and the control group was infected with empty plasmid. After 3 days, exosomes secreted by nrvms of the two groups were obtained, and GFP exos and tbox18 exos were quantitatively analyzed. The rat heart block model was established by injecting acetylcholine chloride into the caudal vein at 72 hours. The biological pacing activity was analyzed, and the automatic rhythm, time-varying effect, and epigenetic characteristics were analyzed through in vitro experiments. 

Results: Western blot and immunofluorescence staining showed that the expression level of the Cx43 marker gene around the sinoatrial node decreased significantly. The quantitative detection results of RT-PCR showed that SCN5A and nkx2-5, Cx43 and other ventricular muscle genes showed a downward trend, while HCN4 sinoatrial node impulse formation gene expression showed an increasing trend. After the establishment of the heart block model, the GFP exos group showed a narrow QRS wave, anterograde, slow atrioventricular junction, and so on; the Tbx18 exos group showed wide QRS wave, retrograde and ventricular ectopic rhythm. The effect of Ca2⁺ oscillation in nrvms cells in the GFP exos group showed poor oscillation and rhythm. Tbox18 exos group had better oscillation and rhythm. 

Conclusion: Exosome-mediated overexpression of embryonic transcription factor tbox18 can induce rat cardiomyocytes to reprogram into sinoatrial node-like cells, providing a new path for heart tissue-related diseases and the development of biological pacemakers.