Young, P. E. | Search bioRxiv

bioRxiv2021

A standardized method to purify cardiomyocytes from individual mouse hearts of any age

Primary cardiomyocytes are invaluable for understanding postnatal heart development. However, a universal method to obtain freshly purified cardiomyocytes without using different agedependent isolation procedures and cell culture, is lacking. Here, we report the development of a standardised method that allows rapid isolation and purification of high-quality cardiomyocytes from individual neonatal through to adult C57BL/6J murine hearts. Langendorff retrograde perfusion, which is currently limited to adult hearts, was adapted for use in neonatal and infant hearts by developing an easier in situ aortic cannulation technique. Tissue digestion conditions were optimised to achieve efficient digestion of hearts of all ages in a comparable timeframe (<14 min). This resulted in a high yield (1.56-2.2x106 cells/heart) and viability (~70-100%) of cardiomyocytes post-isolation. An immunomagnetic cell separation step was then applied to yield highly purified cardiomyocytes (~95%) as confirmed by immunocytochemistry, flow cytometry, and qRT-PCR. For cell-type specific studies, cardiomyocyte DNA, RNA, and protein could be extracted in sufficient yields to conduct molecular experiments. We generated transcriptomic datasets for neonatal cardiomyocytes from individual hearts, for the first time, which revealed nine sex-specific genes (FDR<0.05) encoded on the sex chromosomes. Finally, we also developed an in situ fixation protocol that preserved the native cytoarchitecture of cardiomyocytes (~94% rodshaped post-isolation), and used it to evaluate cell morphology during cardiomyocyte maturation, as well as capture spindle-shaped neonatal cells undergoing cytokinesis. Together, these procedures allow molecular and morphological profiling of high-quality cardiomyocytes from individual hearts of any postnatal age.

cell biology↗

bioRxiv2016

Monozygotic twin pairs discordant for amyotrophic lateral sclerosis carry both common and unique epigenetic differences relevant to disease

Amyotrophic lateral sclerosis (ALS) is a devastating late-onset neurodegenerative disorder in which only a small proportion of patients carry an identifiable causative genetic lesion. Despite high heritability estimates, a genetic etiology for most sporadic ALS remains elusive. Here we report the epigenetic profiling of five monozygotic twin pairs discordant for ALS in whom previous genome sequencing excluded a genetic basis for their disease discordance. By studying cytosine methylation patterns in peripheral blood DNA we identified thousands of large between-twin differences at individual CpGs. While the specific sites of difference were largely idiosyncratic to a twin pair, a proportion (involving GABA signalling) were common to all affected individuals. In both instances the differences occurred within genes and pathways related to neurobiological function and dysfunction. Our findings reveal widespread changes in epigenetic marks in ALS patients, consistent with an epigenetic contribution to disease. These findings may be exploited to develop blood-based biomarkers of ALS and develop further insight into disease pathogenesis. We expect that our findings will provide a useful point of reference for further large scale studies of sporadic ALS.

neuroscience↗