RESUMO
AIM: Understanding the molecular identity of human pluripotent stem cell (hPSC)-derived cardiac progenitors and mechanisms controlling their proliferation and differentiation, is valuable for developmental biology and regenerative medicine. METHODS AND RESULTS: Here we show that chemical modulation of Histone Acetyl Transferases (HATs; by IQ-1) and WNT (by CHIR99021), synergistically enable the transient and reversible block of directed cardiac differentiation progression on hPSCs. The resulting stabilized cardiovascular progenitors (SCPs) are characterized by ISL1pos/KI-67pos/NKX2-5neg expression. In the presence of the chemical inhibitors, SCPs maintain a proliferation quiescent state. Upon small molecules removal SCPs resume proliferation and concomitant NKX2-5 upregulation triggers cell-autonomous differentiation into cardiomyocytes. Directed differentiation of SCPs into the endothelial and smooth muscle lineages confirms their full developmental potential typical of bona fide cardiovascular progenitors. Single-cell RNAseq-based transcriptional profiling of our in vitro generated human SCPs notably reflects the dynamic cellular composition of E8.25-E9.25 posterior second heart field (pSHF) of mouse hearts, hallmarked by NR2F2 expression. Investigating molecular mechanisms of SCP stabilization, we found that the cell-autonomously regulated Retinoic Acid (RA) and BMP signaling is governing SCPs transition from quiescence towards proliferation and cell-autonomous differentiation, reminiscent of a niche-like behavior. CONCLUSION: The chemically defined and reversible nature our stabilization approach provides an unprecedented opportunity to dissect mechanisms of cardiovascular progenitors' specification and reveal their cellular and molecular properties.
RESUMO
COVID-19 affects multiple organs. Clinical data from the Mount Sinai Health System shows that substantial numbers of COVID-19 patients without prior heart disease develop cardiac dysfunction. How COVID-19 patients develop cardiac disease is not known. We integrate cell biological and physiological analyses of human cardiomyocytes differentiated from human induced pluripotent stem cells (hiPSCs) infected with SARS-CoV-2 in the presence of interleukins, with clinical findings, to investigate plausible mechanisms of cardiac disease in COVID-19 patients. We infected hiPSC-derived cardiomyocytes, from healthy human subjects, with SARS-CoV-2 in the absence and presence of interleukins. We find that interleukin treatment and infection results in disorganization of myofibrils, extracellular release of troponin-I, and reduced and erratic beating. Although interleukins do not increase the extent, they increase the severity of viral infection of cardiomyocytes resulting in cessation of beating. Clinical data from hospitalized patients from the Mount Sinai Health system show that a significant portion of COVID-19 patients without prior history of heart disease, have elevated troponin and interleukin levels. A substantial subset of these patients showed reduced left ventricular function by echocardiography. Our laboratory observations, combined with the clinical data, indicate that direct effects on cardiomyocytes by interleukins and SARS-CoV-2 infection can underlie the heart disease in COVID-19 patients. One Sentence SummaryCardiomyocytes derived from human induced pluripotent stem cells treated with interleukins and infected with SARS- CoV- 2 in cultures, show increased release of troponin, disorganization of myofibrils, and changes in beating mirroring specific pathologies in some COVID-19 patients.
