Introduction: New Approach Methodologies (NAMs), such as engineered human myocardium (EHM), serve as valuable 3D models for investigation of cardiac pathophysiology and drug discovery. EHM resemble key features of the juvenile ventricular myocardium in standard 1-3 months cultures and develop contractile dysfunction with hallmarks of fibrosis at 6 months of culture. To test the hypothesis that established pharmacological heart failure treatment using the “fantastic four” will ameliorate contractile dysfunction and fibrosis in EHM, we treated EHM over a period of 3 months using longitudinal contractility assessments.
Methods: EHM were generated from human iPSC-derived cardiomyocytes and stromal cells in a collagen hydrogel. 139 of 144 initially prepared EHM (97 %) were included in the study, meeting inclusion criteria of ring shape geometry and stable function at 3 months of culture. Average human steady state plasma concentrations of Bisoprolol [BIS; 85 nM], Valsartan [VAL; 8 µM], Valsartan + Sacubitrilat [LBQ; 8 µM + 18 nM], Eplerenone [EPL; 800 nM] and Empagliflozin [EMP; 80 nM] were individually added to the defined, serum-free culture medium and replenished at every medium change. Spontaneous beating frequency, contraction amplitude, velocity and tissue tension were assessed using video-optic myrImager recordings. Normal data distribution of repeated measures was tested using D’Agostino test. Repeated measures ANOVA with Dunnett’s multiple comparisons test or Friedman test with Dunn’s multiple comparisons test were used to compare treatment groups with normally or non-normally distributed data, respectively.
Results: At the time of abstract preparation, EHM were treated for up to 47 days (n = 20-24 per group). Relative treatment effects, meeting significance value of p < 0.05, are summarized in table 1.
Table 1: Relative treatment effects compared to control EHM. + = increase, - = decrease, o = no difference
Treatment with LBQ or EMP caused increased contraction amplitude and velocity without affecting beating frequency, while EPL led to increased contraction amplitude without affecting contraction velocity and decreased beating frequency. Interestingly, isolated treatment with VAL showed neutral outcome compared to control. Bisoprolol treated EHM had decreased beating frequency, contraction amplitude and velocity, while tissue tension was increased in comparison to controls.
Conclusion: Fantastic four treatment of EHM with repeated functional measurements over extended culture period recapitulates inotropic and chronotropic therapeutic effects. Importantly, the current study is conducted under defined conditions using serum-free medium. Therefore, NAMs offer a unique setup to investigate treatment effects under controlled levels of neurohumoral agonists. Further functional follow-up is planned until 3 months of treatment and endpoint measurements including tensile force measurement and transcriptome analysis are needed to enhance our understanding of direct cellular treatment effects.
