Contractile abnormalities and altered drug response in engineered heart tissue from Mybpc3-targeted knock-in mice

TY - JOUR

T1 - Contractile abnormalities and altered drug response in engineered heart tissue from Mybpc3-targeted knock-in mice

AU - Stöhr, Andrea

AU - Friedrich, Felix W

AU - Flenner, Frederik

AU - Geertz, Birgit

AU - Eder, Alexandra

AU - Schaaf, Sebastian

AU - Hirt, Marc N

AU - Uebeler, June

AU - Schlossarek, Saskia

AU - Carrier, Lucie

AU - Hansen, Arne

AU - Eschenhagen, Thomas

N1 - © 2013. Published by Elsevier Ltd. All rights reserved.

PY - 2013/10/1

Y1 - 2013/10/1

N2 - Myosin-binding protein C (Mybpc3)-targeted knock-in mice (KI) recapitulate typical aspects of human hypertrophic cardiomyopathy. We evaluated whether these functional alterations can be reproduced in engineered heart tissue (EHT) and yield novel mechanistic information on the function of cMyBP-C. EHTs were generated from cardiac cells of neonatal KI, heterozygous (HET) or wild-type controls (WT) and developed without apparent morphological differences. KI had 70% and HET 20% lower total cMyBP-C levels than WT, accompanied by elevated fetal gene expression. Under standard culture conditions and spontaneous beating, KI EHTs showed more frequent burst beating than WT and occasional tetanic contractions (14/96). Under electrical stimulation (6Hz, 37°C) KI EHTs exhibited shorter contraction and relaxation times and a twofold higher sensitivity to external [Ca(2+)]. Accordingly, the sensitivity to verapamil was 4-fold lower and the response to isoprenaline or the Ca(2+) sensitizer EMD 57033 2- to 4-fold smaller. The loss of EMD effect was verified in 6-week-old KI mice in vivo. HET EHTs were apparently normal under basal conditions, but showed similarly altered contractile responses to [Ca(2+)], verapamil, isoprenaline and EMD. In contrast, drug-induced changes in intracellular Ca(2+) transients (Fura-2) were essentially normal. In conclusion, the present findings in auxotonically contracting EHTs support the idea that cMyBP-C's normal role is to suppress force generation at low intracellular Ca(2+) and stabilize the power-stroke step of the cross bridge cycle. Pharmacological testing in EHT unmasked a disease phenotype in HET. The altered drug response may be clinically relevant.

AB - Myosin-binding protein C (Mybpc3)-targeted knock-in mice (KI) recapitulate typical aspects of human hypertrophic cardiomyopathy. We evaluated whether these functional alterations can be reproduced in engineered heart tissue (EHT) and yield novel mechanistic information on the function of cMyBP-C. EHTs were generated from cardiac cells of neonatal KI, heterozygous (HET) or wild-type controls (WT) and developed without apparent morphological differences. KI had 70% and HET 20% lower total cMyBP-C levels than WT, accompanied by elevated fetal gene expression. Under standard culture conditions and spontaneous beating, KI EHTs showed more frequent burst beating than WT and occasional tetanic contractions (14/96). Under electrical stimulation (6Hz, 37°C) KI EHTs exhibited shorter contraction and relaxation times and a twofold higher sensitivity to external [Ca(2+)]. Accordingly, the sensitivity to verapamil was 4-fold lower and the response to isoprenaline or the Ca(2+) sensitizer EMD 57033 2- to 4-fold smaller. The loss of EMD effect was verified in 6-week-old KI mice in vivo. HET EHTs were apparently normal under basal conditions, but showed similarly altered contractile responses to [Ca(2+)], verapamil, isoprenaline and EMD. In contrast, drug-induced changes in intracellular Ca(2+) transients (Fura-2) were essentially normal. In conclusion, the present findings in auxotonically contracting EHTs support the idea that cMyBP-C's normal role is to suppress force generation at low intracellular Ca(2+) and stabilize the power-stroke step of the cross bridge cycle. Pharmacological testing in EHT unmasked a disease phenotype in HET. The altered drug response may be clinically relevant.

KW - Adrenergic beta-Agonists

KW - Animals

KW - Calcium

KW - Calcium Channel Blockers

KW - Cardiomyopathy, Hypertrophic

KW - Carrier Proteins

KW - Disease Models, Animal

KW - Gene Targeting

KW - Intracellular Space

KW - Isoproterenol

KW - Mice

KW - Mice, Transgenic

KW - Myocardial Contraction

KW - Myocardium

KW - Tissue Engineering

KW - Transcriptome

KW - Verapamil

U2 - 10.1016/j.yjmcc.2013.07.011

DO - 10.1016/j.yjmcc.2013.07.011

M3 - SCORING: Journal article

C2 - 23896226

VL - 63

SP - 189

EP - 198

JO - J MOL CELL CARDIOL

JF - J MOL CELL CARDIOL

SN - 0022-2828

ER -