Human heart-forming organoids recapitulate early heart and foregut development

TLDR

Organoid models of early development exist for intestine, brain, kidney, and other organs, but heart organoids have been lacking, and the architecture of the newly generated HFOs resembles early native heart anlagen that depend on foregut endoderm interactions. The study aims to generate complex, highly structured heart‑forming organoids and to use them to model genetic cardiac defects, such as NKX2.5 knockout phenotypes. Human pluripotent stem cell aggregates were embedded in Matrigel and directed toward cardiac fate by biphasic WNT pathway modulation with small molecules, producing 3D heart‑forming organoids. The resulting HFOs contain a myocardial layer lined by endocardial‑like cells, a septum‑transversum‑like anlagen, distinct anterior and posterior foregut endoderm, a vascular network, and NKX2.5‑knockout organoids recapitulate cardiac malformations seen in transgenic mice.

Abstract

Abstract Organoid models of early tissue development have been produced for the intestine, brain, kidney and other organs, but similar approaches for the heart have been lacking. Here we generate complex, highly structured, three-dimensional heart-forming organoids (HFOs) by embedding human pluripotent stem cell aggregates in Matrigel followed by directed cardiac differentiation via biphasic WNT pathway modulation with small molecules. HFOs are composed of a myocardial layer lined by endocardial-like cells and surrounded by septum-transversum-like anlagen; they further contain spatially and molecularly distinct anterior versus posterior foregut endoderm tissues and a vascular network. The architecture of HFOs closely resembles aspects of early native heart anlagen before heart tube formation, which is known to require an interplay with foregut endoderm development. We apply HFOs to study genetic defects in vitro by demonstrating that NKX2.5 -knockout HFOs show a phenotype reminiscent of cardiac malformations previously observed in transgenic mice.