Amniotic fluid-derived stem cells demonstrated cardiogenic potential in indirect co-culture with human cardiac cells

Amniotic fluid-derived stem cells (AFSC) have been shown to be broadly multipotent and non-tumorogenic. Previous studies of direct mixing of AFSC and neonatal rat ventricle myocytes indicated evidence of AFSC cardiogenesis. In this study, we examined human AFSC cardiogenic potential in indirect co-culture with human cardiac cells in conditions that eliminated the possibility of cell fusion. Human AFSC in contact with human cardiac cells showed expression of cardiac troponin T (cTnT) in immunohistochemistry, and no evidence of cell fusion was found through fluorescent in situ hybridization. When indirectly co-cultured with cardiac cells, human AFSC in contact with cardiac cells across a thin porous membrane showed a statistically significant increase in cTnT expression compared to non-contact conditions but lacked upregulation of calcium modulating proteins and did not have functional or morphological characteristics of mature cardiomyocytes. This suggests that contact is a necessary but not sufficient condition for AFSC cardiac differentiation in co-culture with cardiac cells.