The human amniotic fluid stem cell secretome exerts cardio-active paracrine potential for myocardial repair and regeneration

Abstract

Background & Aim Functional replacement of cardiomyocytes following injury is the sine qua non condition for heart regeneration. We previously reported that human amniotic fluid-derived stem cells (hAFS) are cardioprotective on rodent ischemic myocardium and cardiac cells exposed to cardiotoxicity. Here we investigated whether hAFS secretome (all paracrine factors released in the cell-conditioned medium, hAFS-CM, including extracellular vesicles, hAFS-EV) can trigger cardiomyocyte cell cycle re-entry. We also evaluated gestational age influence on the secretome of II trimester hAFS from leftover samples of prenatal amniocentesis (fetal hAFS) over III trimester cells from clinical waste of scheduled C-section delivery (perinatal hAFS). Methods, Results & Conclusion c-KIT+ hAFS were isolated as previously described and preconditioned by 1% O2 for 24h. A preclinical mouse model of myocardial infarction (MI) was treated with single intra-myocardial injection of fetal hAFS-CM over hAFS-EV to assess cardiac repair and cardiomyocyte cell cycle progression by bromodeoxyuridine (BrdU) uptake 4 weeks post-MI. Neonatal mouse ventricular cardiomyocytes (mNVCM) were isolated from R26pFUCCI2 transgenic pups with a nuclear probe system to fluorescently tag cell cycle stages (G1 by mCherry; S-G2-M by mVenus/GFP) and stimulated by fetal versus perinatal hAFS-CM to investigate cardiomyocyte renewal. Fetal hAFS-CM injection soon after MI counteracted scarring, supported local angiogenesis and reactivation of epicardial progenitors. Fetal hAFS-EV recapitulated all the beneficial effects of whole hAFS-CM, but for vessel formation while significantly counteracted cardiac function worsening. BrdU-positive resident cardiomyocytes were similarly increased by 2.5-fold when primed with either fetal hAFS-CM or -EV over vehicle-treated mice (p Our preliminary findings suggest that hAFS secretome can enhance cardiac repair and sustain endogenous regenerative mechanisms. Further analyses are ongoing to evaluate the effect of perinatal versus fetal hAFS-EV on myocardial renewal, so to define the most cardio-active secretome formulation.