Objective      To construct fusion cells with induced pluripotent stem cells (iPSc) and primary cardiac myocytes

in vitro

and to investigate biological features of the fusion cells.       Methods      Polyethylene glycol (PEG-4000) was used to mediate the cell fusion of iPSc

derived from green fluorescent protein (GFP) transgenes (octamer-binding transcription factor-4

Oct-4) mouse and cardiac myocytes from neonatal mouse. Morphological changes of the fusion cells were observed dynamically after alkaline phosphatase (AKP) staining. Specific proteins of stem cells and cardiac myocytes in fusion cells were detected by immunofluorescence. Chromosome karyotype analysis were performed to determine whether the occurrence of nuclear fusion and degree of integration.       Results      Fusion cells were constructed successfully by polyethylene glycol mediation. Colony-like cell clusters appeared in 4 d after fusion. The AKP positive rate of iPSc were 0.935±0.039

0.939±0.022

0.954±0.017

and 0.944±0.027 at the 2nd

3rd

4th and 5th days respectively

and that of fusion cells were 0.761±0.044

0.740±0.023

0.681±0.034

and 0.748±0.045 at the corresponding days respectively. At the same time points

there were significant differences between iPSc AKP-positive rates and those of fusion cells (

P

<

0.05). In the initial stage

fusion cells mainly displayed iPSc characteristics

with Oct-4 positive while cTnT negative. Then the fusion cells began to display both characteristics of iPSc and cardiac myocytes in 7 d after fusion

with positive expression of Oct-4 and cTnT. More than 80% of fusion cells had 76 to 80 chromosomes.       Conclusion      Fusion cells from diploid iPSc and diploid myocardial cells display the characteristics of the two parental cells and show bidirectional reprogramming.