A framework for developing sex-specific engineered heart models

Abstract

The convergence of tissue engineering and patient-specific stem cell biology has enabled the engineering of in vitro tissue models that allow the study of patient-tailored treatment modalities. However, sex-related disparities in health and disease, from systemic hormonal influences to cellular-level differences, are often overlooked in stem cell biology, tissue engineering and preclinical screening. The cardiovascular system, in particular, shows considerable sex-related differences, which need to be considered in cardiac tissue engineering. In this Review, we analyse sex-related properties of the heart muscle in the context of health and disease, and discuss a framework for including sex-based differences in human cardiac tissue engineering. We highlight how sex-based features can be implemented at the cellular and tissue levels, and how sex-specific cardiac models could advance the study of cardiovascular diseases. Finally, we define design criteria for sex-specific cardiac tissue engineering and provide an outlook to future research possibilities beyond the cardiovascular system.

Keywords: Cardiovascular diseases.

Fig. 1. Factors contributing to sex-based cardiac differences.

Differences between male and female cardiac physiology in humans arise from genetic, epigenetic, sex hormone, environmental, behavioural and lifestyle factors, which interact and change throughout life and are not easy to delineate^–.

Fig. 2. Workflow for creating engineered cardiac models.

Engineered cardiac tissue models are 3D constructs that are grown using cells, biomaterials and exogenous factors to recapitulate patient-specific cardiac phenotypes in vitro. Regardless of the specific tissue design, a common workflow can be outlined and each step can be designed in a sex-specific way. Human induced pluripotent stem cells (iPSCs) are first derived from donors, differentiated into cardiomyocytes and supporting cells, and seeded into a biomaterial. The resulting engineered tissue is cultured in an appropriate culture medium and subjected to electromechanical conditioning. Finally, the cardiac tissue is matured to recapitulate the phenotype of the donor. ECM, extracellular matrix.

Fig. 3. Engineered cardiac tissue models.

a | Human induced pluripotent stem cell-derived cardiomyocytes and supporting cardiac fibroblasts encapsulated in a fibrin hydrogel can be subjected to tension between two elastic pillars. b | The Biowire II platform allows the creation of electrophysiologically distinct atrial and ventricular tissues attached to two polymer wires. c | The I-Wire platform combines neonatal ventricular rat cells in a fibrinogen–Matrigel–thrombin hydrogel into a polydimethylsiloxane mould with a channel for the 3D tissue and titanium wires on either side. d | Chamber-specific heart tissues can be created from ventricular and atrial human pluripotent stem cell-derived cardiomyocytes embedded in a collagen hydrogel. e | Using a hydrogel derived from human omentum and patient-specific cardiomyocytes and endothelial cells, personalized bioinks can be created to bioprint vascularized patches. f | Tissue-engineered ventricles are prepared from seeding ellipsoidal ventricle scaffolds with cardiomyocytes. Their contractile properties are evaluated by pressure–volume catheterization in the heart bioreactor. g | Collagen can be 3D-printed using freeform reversible embedding of suspended hydrogels to generate parts of the human heart at different scales. The selection of the most appropriate model depends on the specific question and the functional outcomes being measured (for example, tissues anchored to pillars are especially useful for studies requiring measurements of force generation). Ultimately, the choice should be made at the user’s discretion. ECT, engineered cardiac tissue. Panel b reprinted with permission from ref., Elsevier. Panel c reprinted with permission from ref., Elsevier. Panel d reprinted from ref., CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Panel e reprinted from ref., CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Panel f reprinted from ref., Springer Nature Limited. Panel g reprinted with permission from ref., AAAS.