# Investigating PKD2 deficiency-associated cardiomyopathies using hESC-cardiomyocytes and bioengineered 3D ventricular cardiac tissue strips

## TL;DR

This study uses human stem cell-derived heart cells and 3D tissue models to investigate how a kidney disease gene defect causes heart problems.

## Contribution

The study introduces 3D bioengineered ventricular cardiac tissue strips as a novel model for studying PKD2 deficiency-related heart issues in humans.

## Key findings

- Polycystin-2 deficiency reduces heart tissue contractility and alters contraction/relaxation speeds.
- ER stress and reduced sarcoplasmic reticulum Ca2+-ATPase activity are key mechanisms in the observed heart dysfunction.
- Reducing ER stress or boosting Ca2+-ATPase activity partially restores normal heart function in the model.

## Abstract

Autosomal dominant polycystic kidney disease is a highly prevalent hereditary renal disorder caused by mutations in either polycystin-1 or polycystin-2. These patients also develop cardiomyopathies. However, the mechanism of how polycystin-2 defects could lead to cardiomyopathies is poorly understood. Moreover, previous studies using animal models cannot fully represent human cardiomyocyte pathophysiology. Human embryonic stem cells were differentiated into cardiomyocytes. These cardiomyocytes were transduced with viral-based polycystin-2-shRNAs, then mixed with an appropriate amount of human fetal fibroblasts, collagen, and Matrigel, and biofabricated into 3D bioengineered ventricular cardiac tissue strips (hvCTS). We used these 3D hvCTS and 2D human embryonic stem cells-derived cardiomyocytes to recapitulate polycystin-2 deficiency-associated cardiac contractile defects and to explore underlying mechanisms. Knockdown of polycystin-2 decreased the contractile force and slowed down the contraction and relaxation velocities in hvCTS, indicative of contractile malfunction. The underlying mechanisms involved an elevated endoplasmic reticulum stress and a decreased activity of sarcoplasmic reticulum Ca2+-ATPases. Alleviation of endoplasmic reticulum stress by small molecular chaperones 4-phenylbutyrate/tauroursodeoxycholic acid or stimulation of sarcoplasmic reticulum Ca2+-ATPase activity by CDN1163 partially rescued the polycystin-2 deficiency-associated contractile dysfunction in hvCTS. This study used 3D hvCTS and 2D human embryonic stem cells-derived cardiomyocytes as novel disease models to recapitulate PKD2 deficiency-associated contractile defects. We found that knockdown of polycystin-2 induces cardiomyopathies via elevating endoplasmic reticulum stress and decreasing sarcoplasmic reticulum Ca2+-ATPase activity. The results provide novel insights about polycystin-2 deficiency-associated cardiomyopathies in polycystic kidney disease patients.