Induced pluripotent stem cell-based modeling of resiliency: understanding the molecular mechanisms of exceptional longevity
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Abstract
Dynamic resiliency, or the ability to respond to and recover from stress, declines with age and results in increased frailty and susceptibility to disease. Individuals with exceptional longevity (EL) display remarkable resiliency and healthspan by delaying or escaping aging-related disease. However, the underlying mechanisms that drive resiliency remain unclear. Moreover, models of human resilience that allow for the functional testing of interventions are virtually non-existent. To address this need, we leveraged access to EL and control cohorts to generate a first-of-its-kind bank of peripheral blood mononuclear cells (PBMCs) and resultant induced pluripotent stem cells (iPSCs). As a first aim of this study, we wanted to characterize the EL immune system at unprecedented resolution to test the hypothesis that these subjects harbor a unique immune make-up leading to increased resiliency to infection. We profiled PBMCs from seven of the centenarians (over 100 years of age) in our bank at single cell resolution through RNA sequencing with cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) antibodies, as well as developing a novel 40-color immune flow cytometry panel. We integrated these data with existing datasets improving the number of centenarian subjects, as well as including a broad range of subjects across the typical human lifespan (20-80 years). These studies revealed that EL subjects retain a higher cell type diversity in the immune system, specifically maintaining the effector immune cells typically lost with age. Additionally, we identified a separate and distinct transcriptional signature of the EL immune system which did not follow the profiles typically observed with age.
In aim 2, we sought to generate a renewable source of longevity-specific biomaterial which could fuel the study of resiliency in these subjects. To do this, we combined associated phenotypic data with omics-based aging clocks to identify individuals at the extremes of resiliency and frailty within our bank. We collected 110 EL subjects including centenarians, centenarian offspring, and offspring age-matched controls. From these subjects, we generated 20 iPSC lines and validated these lines for stemness, pluripotency, and ability to differentiate into cell types of aging-related interest such as neurons. Importantly, we observed no failures in the ability to generate high quality iPSC lines from EL subjects.
This bank was utilized in aim 3 to build a human, iPSC-based model of resiliency. IPSC-derived neurons were generated from EL and non-EL subjects and exposed to cellular stress to stimulate responses aimed at restoring cellular function. Following stress, bulk RNA sequencing was performed to establish the transcriptional signatures of stress response and adaptation. EL-derived cells displayed a more resilient molecular signature represented by significant upregulation of genes involved in protein quality control, integrity and functionality, and resistance to Alzheimer’s Disease as compared to non-EL controls.
Our in vitro model of functional resilience synergizes omics-based discovery with the flexibility and functional impact of iPSC-based models. This model will allow for the cross validation of longevity-related discoveries and will be leveraged to identify biomarkers of resilience or decline at the level of the individual and to develop novel, personalized therapeutics for aging-related disease.
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2025