Organ Explant Culture of Neonatal Rat Ventricles: A New Model to Study Gene and Cell Therapy. e59290

• Published in: PloS one 2013-03, Vol.8 (3)
• Main Authors: Haan, A Deniseden, Veldkamp, Marieke W, Bakker, Diane, Boink, Geert JJ, Janssen, Rob B, Bakker, M Tde, Tan, Hanno L
• Format: Article
• Language: English
• Subjects: Actin
• ISSN: 1932-6203
• DOI: 10.1371/journal.pone.0059290

Testing cardiac gene and cell therapies in vitro requires a tissue substrate that survives for several days in culture while maintaining its physiological properties. The purpose of this study was to test whether culture of intact cardiac tissue of neonatal rat ventricles (organ explant culture) may be used as a model to study gene and cell therapy. We compared (immuno) histology and electrophysiology of organ explant cultures to both freshly isolated neonatal rat ventricular tissue and monolayers. (Immuno) histologic studies showed that organ explant cultures retained their fiber orientation, and that expression patterns of alpha -actinin, connexin-43, and alpha -smooth muscle actin did not change during culture. Intracellular voltage recordings showed that spontaneous beating was rare in organ explant cultures (20%) and freshly isolated tissue (17%), but common (82%) in monolayers. Accordingly, resting membrane potential was -83.9 plus or minus 4.4 mV in organ explant cultures, -80.5 plus or minus 3.5 mV in freshly isolated tissue, and -60.9 plus or minus 4.3 mV in monolayers. Conduction velocity, measured by optical mapping, was 18.2 plus or minus 1.0 cm/s in organ explant cultures, 18.0 plus or minus 1.2 cm/s in freshly isolated tissue, and 24.3 plus or minus 0.7 cm/s in monolayers. We found no differences in action potential duration (APD) between organ explant cultures and freshly isolated tissue, while APD of monolayers was prolonged (APD at 70% repolarization 88.8 plus or minus 7.8, 79.1 plus or minus 2.9, and 134.0 plus or minus 4.5 ms, respectively). Organ explant cultures and freshly isolated tissue could be paced up to frequencies within the normal range for neonatal rat (CL 150 ms), while monolayers could not. Successful lentiviral (LV) transduction was shown via Egfp gene transfer. Co-culture of organ explant cultures with spontaneously beating cardiomyocytes increased the occurrence of spontaneous beating activity of organ explant cultures to 86%. We conclude that organ explant cultures of neonatal rat ventricle are structurally and electrophysiologically similar to freshly isolated tissue and a suitable new model to study the effects of gene and cell therapy.