Prenatal 3i-0777 treatment attenuates left ventricular hypertrabeculation and dysfunction in a retinoic acid-induced mouse model

Excessive left ventricular trabeculation and thinning of the compacted myocardium arise during cardiac development and may be accompanied by myocardial dysfunction. Gestational exposure to all-trans retinoic acid (ATRA) induces a comparable phenotype in mice, providing a model for evaluating prenatal pharmacological intervention. We examined whether 3i-0777, a small-molecule enhancer of GATA4-NKX2-5 transcriptional synergy, could attenuate these structural and functional abnormalities. Pregnant C57BL/6NCrl dams were randomly assigned to untreated control, vehicle control, ATRA, or ATRA plus 3i-0777 groups (12 independent litters per group). Both ATRA-exposed groups received ATRA (50 mg/kg) on embryonic day (E)12.5. In the ATRA plus 3i-0777 group, 3i-0777 (15 mg/kg) was administered as a separate injection concurrently with ATRA at E12.5, followed by 5 mg/kg every 8 h (three doses per day) on E13.5-E15.5. At postnatal day 1, one pup was randomly selected from each litter for echocardiography and subsequent histomorphometry. The echocardiographic and histomorphometric ratios of non-compacted to compacted myocardial layer thickness (N/C ratios) were higher, and the absolute magnitude of global longitudinal strain (|GLS|) was lower, in the ATRA group than in either control group (all adjusted P < 0.001). Compared with the ATRA group, the ATRA plus 3i-0777 group had lower echocardiographic and histomorphometric N/C ratios (0.58 {+/-} 0.19 vs 2.19 {+/-} 0.18 and 0.90 {+/-} 0.33 vs 2.46 {+/-} 0.48, respectively), higher |GLS| (25.9 {+/-} 2.5% vs 15.3 {+/-} 2.7%), and a smaller left ventricular internal diameter at end-diastole (1.15 {+/-} 0.06 vs 1.42 {+/-} 0.10 mm; all adjusted P < 0.001). These findings provide proof of concept that ATRA-induced left ventricular hypertrabeculation and dysfunction can be pharmacologically attenuated in utero.