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Human Cardiac Progenitors Grown Under Microgravity Conditions Generate Myocytes With High Conduction Velocities
Author(s) -
Prodan Nicole,
Islas Jose,
Iyer Dinakar,
McConnell Bradley,
Birla Ravi,
Schwartz Robert J
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.676.3
Subject(s) - myocyte , microbiology and biotechnology , chemistry , biophysics , medicine , biology
Clinical trials using human adipogenic mesenchymal stem cells (hAdMSC) for the treatment of cardiac diseases have shown improvement in cardiac function and were proven safe. However, hAdMSCs do not convert efficiently into cardiac myocytes or vasculature. Thus, reprogramming hADMSCs into mature myocytes may fare better in future investigations. To reprogram hAdMSCs into electrically conductive cardiac myocytes (CM), we pioneered a 3‐step reprogramming strategy that uses proven MESP1/ETS2 transcription factors, beta 2‐adrenergic receptor (b2AR) and micro‐gravity signaling induced in 3D cardio‐spheroids. In stage 1, ETS2 and MESP1 activated Nkx2.5, Tbx5, Mef2C, dHAND and GATA4 during the conversion of hAdMSCs into cardiac progenitor cells (CPCs). Next, in stage 2, b2AR activation repositioned CPCs into de novo myocytes, along with the appearance of RYR2, CAV2.1, CAV3.1, Nav1.5, SERCA2 and CX45 gene transcripts, myofibrils and action potentials. In stage 3, electrical conduction fostered by 3D cardio‐spheroids formed in a Synthecon®, Inc. rotating bioreactor that mimics micro‐gravity induced the appearance of hypoxic genes: HIF1a/b, PCG1a/b and NOS2 which coincided with the robust activation of adult contractile genes MYH6, MYH7 and TNNI3, ion channel genes and the appearance of hyperpolarization‐activated and cyclic nucleotide‐gated channels (HCN1‐4). Conduction velocities doubled to ~200mm/s after hypoxia, and doubled yet again after dissociation of the 3D cell clusters to ~400mm/s. By comparison, normal conduction velocities within working ventricular myocytes in the whole heart range from 0.5–1m/s. Epinephrine stimulation of stage‐3 myocytes in patches resulted in an increase in amplitude of the electrical wave, indicative of mature CMs. Our efficient protocol converted hAdMSC into highly conductive CM and demonstrated the potential utilization of stage‐3 cells for tissue engineering applications for cardiac repair. Support or Funding Information Supported by a grant from the Center for Advanced Science in Space This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .