Evidence of rat cardiomyocyte mitosis in vitro

Objective To inverstigate myocardial cell mitosis and proliferation in vitro. Methods Primary neonatal rat cardiomyocytes were cultured from 0 hour to 12 days and 5 days,and double stained by cardiac tropnin-T( c Tn T),phospho histone H3( H3P) and tubulin using immunofluorescence technique. Cardiomyocytes with mitosis were searched with the living cell station and a fluorescence microscope. Results Primary cardiomyocytes were lived well and had a high purity. The tubulin change at every mitosis period was observed. The cardiomyocytes were not swelled up and maintained squamous under mitosis condition. The nuclear shape in mitosis prophase was regular,the chromatin became condensation and H3 P began to express; At prometaphase,karyotheca broken and spindle formed; Chromosomes were arranged in the equatorial plane and the shape of spindle was very typical at metaphase. The character at anaphase was that the chromatids separated and moved towards the poles and the spindle extended. At telophase,daughter nucleus came into being and parallel microtubule distributed between two daughter nucleus; At cytokinesis period,two daughter cells were generated and a small amount of silky microtubules located between two daughter cells were seen after the two daughter cells separation. The conjugate nuclei of primary cultured neonatal rat cardiomyocytes from 1 day to 12 days were seldom observed in all cell division image. The division phase of cardiomyocytes was observed and the proportions of division cell were approximately 2 /127( 1. 57%) and 1 /92( 1. 09%) at cultured 3 days,3 /69( 4. 35%) and 5 /163( 3. 07%) at 7days,2 /100( 2%) and 0 /60( 0) at 12 days. Conclusion Cardiomyocyte in vitro exists completing mitosis division in few cells which is cell evidence of cardiac regeneration and proliferation.