Hypertension Cell Models for Research

Hypertension is a major global health issue, affecting over 1.28 billion adults worldwide, according to the World Health Organization (WHO). It is a leading risk factor for cardiovascular diseases, stroke, and kidney failure, contributing to approximately 10.8 million deaths annually. The prevalence of hypertension is increasing, particularly in low- and middle-income countries. Key risk factors include unhealthy diet, physical inactivity, obesity, tobacco use, and excessive alcohol consumption. The 5-year survival rate for hypertension-related complications varies, but uncontrolled hypertension significantly reduces life expectancy. Early detection and management are critical to prevent severe outcomes.

Hypertension is a complex, multifactorial disease with genetic, environmental, and lifestyle components. It is an ideal model for mechanistic studies due to its well-defined physiological pathways (e.g., renin-angiotensin-aldosterone system, sympathetic nervous system) and the availability of large public datasets from genome-wide association studies (GWAS) and transcriptomic analyses. Open questions include the identification of novel drug targets, understanding drug resistance mechanisms, and the role of rare genetic variants. Gene-edited cell models enable precise manipulation of candidate genes to study their function in relevant cell types, such as vascular smooth muscle cells, endothelial cells, and renal cells.

While hypertension is not a cancer, it involves dysregulation of several signaling pathways that are also relevant in oncology, such as:

• • Renin-Angiotensin-Aldosterone System (RAAS): Overactivation leads to vasoconstriction and sodium retention.
• • Sympathetic Nervous System (SNS): Increased activity raises heart rate and vascular tone.
• • Nitric Oxide (NO) Signaling: Impaired NO production causes endothelial dysfunction.
• • Inflammatory Pathways: Chronic low-grade inflammation contributes to vascular remodeling.

These pathways are interconnected and offer multiple targets for therapeutic intervention.

Data from GWAS and candidate gene studies, as compiled in ClinVar and NCBI Gene.

Key signaling networks in hypertension include:

• • RAAS Pathway: Key nodes: ACE, AGT, AT1R, aldosterone synthase.
• • Sympathetic Nervous System: Key nodes: beta-1 adrenergic receptor, alpha-1 adrenergic receptor.
• • Endothelial Function: Key nodes: eNOS, endothelin-1, VEGF.
• • Renal Sodium Handling: Key nodes: ENaC, NKCC2, NCC.

These networks are targets for existing antihypertensive drugs and are being explored for novel therapies.

Organoids derived from induced pluripotent stem cells (iPSCs) offer a more physiologically relevant model for studying hypertension, as they can recapitulate vascular and renal tissue architecture.

Animal models are essential for studying hypertension in vivo. Examples include:

• • Spontaneously Hypertensive Rats (SHR): Genetic model of essential hypertension.
• • Angiotensin II Infusion Model: Induced hypertension via chronic infusion.
• • DOCA-salt Model: Induced hypertension via deoxycorticosterone acetate and salt.
• • Genetically Engineered Mouse Models (GEMMs): Knockout or knock-in of genes such as ACE, AGT, or NOS3.
• • Patient-Derived Xenografts (PDX): Less common for hypertension, but useful for studying tumor-associated hypertension.

CRISPR-Cas9 gene editing enables the creation of isogenic cell lines with precise genetic modifications, providing powerful tools for hypertension research. Examples include:

• • ACE knockout cell lines: To study the role of ACE in angiotensin II production.
• • AGT knock-in cell lines with the M235T variant: To assess the functional impact of this polymorphism.
• • NOS3 knockout cell lines: To investigate endothelial dysfunction.
• • NR3C2 (mineralocorticoid receptor) knockout cell lines: To study aldosterone signaling.

These sequence-verified models are commercially available and accelerate research by providing consistent, reproducible systems for functional studies and drug screening.

Gene-edited cell lines are used to validate the function of genes implicated in hypertension. For example, knocking out ACE in endothelial cells reduces angiotensin II production, confirming its role in vasoconstriction. Similarly, introducing the AGT M235T variant into a renal cell line can increase angiotensinogen secretion, providing a model to study the variant's effect.

Isogenic cell line pairs (wild-type vs. knockout) are used in high-throughput screening to identify compounds that selectively target mutant or overactive pathways. For instance, ACE knockout cells can be used to screen for ACE-independent antihypertensive agents. Additionally, resistance to antihypertensive drugs can be modeled by exposing cells to increasing drug concentrations and selecting for resistant clones.

CRISPR-based synthetic lethality screens can identify genes that are essential when a hypertension-related gene is mutated. This approach can uncover novel biomarkers and therapeutic targets. For example, in cells with NOS3 knockout, screening for genes whose depletion causes cell death may reveal compensatory pathways that could be targeted pharmacologically.