Three-dimensional engineered heart tissue from neonatal rat cardiac myocytes

A technique Is presented that allows neonatal rat cardiac myocytes to form spontaneously and coherently beating 3-dimensional engineered heart tissue (EHT) in vitro, either as a plane biconcaval matrix anchored at bath sides on Velcro-coated silicone tubes or as a ring. Contractile activity was moni tored in standard organ baths or continuously in a CO2 incubator for up to 18 days (=26 days after casting). Long-term measurements showed an increase in force between days 8 and 18 after casting and stable forces thereafter, At day 10, the twitch amplitude (TA) of electrically paced EHTs (average l ength x width x thickness, 11 x 6 x 0.4 mm) was 0.51 mN at length of maxima [ force development (L-max) and a maximally effective calcium concentration . EHTs showed typical features of neonatal rat heart: a positive force-leng th and a negative force-frequency relation, high sensitivity to calcium (EC 50 0.24 mM), modest positive inotropic, (increase in TA by 46%) and pronoun ced positive lusitropic effect of isoprenaline (decrease in twitch duration by 21%). Both effects of isoprenaline were sensitive to the muscarinic rec eptor agonist carbachol in a pertussis toxin-sensitive manner. Adenovirus-m ediated gene transfer of beta-galactosidase into EHTs reached 100% efficien cy. In summary, EHTs retain many of the physiological characteristics of ra t cardiac tissue and allow efficient gene transfer with subsequent force me asurement. (C) 2000 John Wiley & Sons, Inc.