Abstract Background/Introduction Mechanistic discoveries mostly rely on animal research or bioengineered human models; these platforms often fail to recapitulate human physiology and disease. Here we report a novel approach using adult human hearts, available from the UK National Health Service, explanted exclusively for research and employed to prepare living myocardial slices (LMSs). LMSs are ultrathin (300μm) sections of living cardiac tissue that maintain the native structure and function, and can be kept in culture for weeks/months under physiological electro-mechanical conditions. Purpose We assessed whether preparing LMSs from donor human hearts is a viable and practical alternative to other research platforms. We then tested if it is possible to delay tissue utilisation, to maximise throughput, overcome out-of-hours logistical difficulties and enable the sharing of tissue with multiple centres. Methods From July 2024 to October 2025, we accepted 54 hearts (30 donated after circulatory death, 24 donated after brain death). The donors were 62.15 +/- 15.38 years of age (Mean +/- SD). We only accepted hearts from donors without cardiovascular disease or current infections and were within 6h (hours) transport time (transported in saline solution at 4°C). LMSs were prepared as described by our group previously (Camelliti et al., 2011; Pitoulis et al., 2020; van der Geest et al., 2025; Watson et al., 2019, 2017). Biopsies were stored in cardioplegia solution between 5-16h at 4°C prior to LMS generation. Results We could prepare 30-50 LMSs from a 1cm3 LV transmural biopsy. LMSs were viable and robust: (force transient amplitude at 2.2μm sarcomere length: 8.8 +/- 7.2mN/mm2; passive force: 9.4 +/- 6.6mN/mm2 (n=39)). There was no statistical difference in both force transient amplitude and passive force between fresh LMS and LMS from biopsies stored in cardioplegia for 5h (active force fresh: 7.8 +/- 4.8mN/mm2; post-cardioplegia: 26.4 +/ 24mN/mm2; paired t-test: p=0.272; passive force fresh: 6.1+/-1.34mN/mm2; post-cardioplegia: 13.5+/-5.4mN/mm2; p=0.132 (n=3 hearts from 8 fresh and 11 post-cardioplegia LMSs)), or from biopsies stored in cardioplegia for 5-16h (active force fresh: 3.104 +/- 2.573mN/mm2; post-cardioplegia: 5-6h: 4.931 +/- 6.406mN/mm2; 7-8h: 2.026 +/-2.114mN/mm2; 9h+ 2.599 +/- 2.224mN/mm2; one-way anova: p=0.442; passive force fresh: 7.569 +/- 6.147mN/mm2; post-cardioplegia: 5-6h: 9.039 +/- 6.826mN/mm2; 7-8h: 6.717 +/- 2.914mN/mm2; 9h+: 10.918 +/- 5.675mN/mm2; p=0.2502 (n=11 hearts from 27 fresh, 15 5-6h, 8 7-8h and 9 9-16h post-cardioplegia LMSs)). Conclusions Adult donor heart tissue is a viable source of LMSs and can lead to valuable research in mechanisms of disease and treatment, as a valid alternative to animal research or bioengineered models. Transmural biopsies could be stored for up to 16 hours post-dissection with no significant effect on contractile function.
Reitemeier et al. (Fri,) studied this question.
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