Evaluation of immature cardiac myocyte viability after 24 hours of hypothermic preservation.

Abstract

In this study, we evaluated cardiac myocyte viability and function under hypothermic conditions using three types of storage solutions; saline solution (SS), Euro-Collins solution (ECS) and MCDB 107 medium (MM). Cardiac myocytes were isolated from neonatal rat ventricles by collagenase dispersion and cultured for 4 days with MCDB 107 medium. A total of 12.5 x 10(5) myocytes/culture dish were used and the myocytes were incubated at 4 degrees C for 6, 12, 18 and 24 hrs in the various storage solutions. After each incubation time, CPK and LDH were measured in the storage solutions. The myocytes were then cultured in MCDB 107 medium and incubated for 24 hrs at 37 degrees C to evaluate the recovery of the myocyte beating rate. In group MM (n = 7), the recovery ratio of the myocyte beating rate was 99.2 percent of control (beating rate prior to hypothermic incubation) at 6 hours, 104.6% at 12 hrs and 44.8% at 24 hrs. Groups SS and ECS (n = 7 each) had significantly lower recovery ratios than the MM group (at 6 hrs: 74.3, 34.0; at 12 hrs: 61.0, 32.2; at 24 hrs: 0.0, 0.0 percent of control, respectively). Release of CPK and LDH in the MM group gradually increased and at 24 hrs was 28.6 IU/l and 93.6 IU/l, respectively. However, the SS group had significantly increased CPK and LDH values at 24 hrs (CPK: 66.9, LDH: 164.2). The ECS group showed the greatest increase in both markers (CPK: 317.5, LDH: 421.2). In summary, saline solution showed a beneficial effect on recovery of myocyte viability at 12 hours compared to Euro-Collins solution, however, MCDB 107 medium had the best overall protective effect on cultured myocytes. Accordingly, alternate hypothermic storage solutions, such as cell-culture medium, may have protective characteristics that are suitable for cardiac preservation.