Biology subjects

Sala-Hamrick, K. E.

Publications and source records attributed to Sala-Hamrick, K. E..

4 recordsLinked to original sources

bioRxiv2026

Lead Exposure During Differentiation Perturbs Electrophysiological Function in iPSC Derived Cardiomyocytes in a Cell Line-Dependent Manner

Lead (Pb) exposure is strongly associated with cardiovascular diseases, but the effects of developmental Pb exposure on the electrophysiological properties of human cardiomyocytes have not yet been investigated. Using human induced pluripotent stem cell (iPSC)-derived cardiomyocytes, we investigated the effects of human-relevant Pb exposure during ventricular cardiomyocyte differentiation on action potential properties and calcium dynamics in differentiated myocytes. We exposed 2 iPSC lines, from 1 male and 1 female donor, to Pb (0.5 or 5 micromolar) or control during only the first 8 days of differentiation, prior to functional maturation. Differentiation was carried out using an established protocol involving temporal modulation of Wnt signaling, followed by purification and maturation of contractile myocytes. We measured action potential properties and calcium dynamics using fluorescent dyes and optical mapping. We hypothesized that Pb exposure would adversely affect cardiomyocyte function, with effects persisting after cessation of exposure. In keeping with this hypothesis, we found significant Pb-induced changes in calcium (Ca) transients and action potential dynamics that were concentration and cell line specific and persisted well after exposure had ended. In the female cell line, beat frequency significantly increased with Pb exposure for both action potentials and Ca transients, while in the male cell line, beat frequency significantly decreased with Pb exposure for action potentials and increased for Ca transients. For voltage measurements, we observed significantly increased arrythmias with Pb exposure in both cell lines. Significant changes in repolarization and recovery time (for voltage and Ca, respectively) were present with Pb exposure in both cell lines. Gene expression of Ca transporters/channels and K channels were not affected, suggesting that persistent effects of Pb exposure on cardiomyocyte electrophysiology may occur through post-translational mechanisms. Overall, this study paves the way for future work to examine how exposure to Pb impacts long-term cardiac function through developmental programming.

pharmacology and toxicology↗

bioRxiv2026

Human-Relevant Lead Exposure During Differentiation Alters the Transcriptomic Profile of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Cardiovascular disease (CVD) etiology is strongly influenced by lead (Pb) exposure, but the underlying molecular and functional mechanisms are unclear, particularly during development. Using human induced pluripotent stem cell (iPSC) derived cardiomyocytes, we examined the effects of human-relevant Pb exposure during ventricular cardiomyocyte differentiation on transcription at several time points. We used an established protocol that temporally modulates Wnt signaling to differentiate iPSCs into contractile cardiomyocytes and exposed cells to 0.5 {micro}M, 5 {micro}M Pb, or control conditions during the first eight days of differentiation. Gene expression profiling on days 1, 2, 6, and 15 revealed significant Pb-induced changes in gene expression and dysregulation of pathways related to heart development and function, epigenetic machinery, and mitochondrial function throughout differentiation. Using BMDExpress3 modelling software, we calculated gene and biological pathway-specific best fit benchmark concentrations (BMCs) and found gene expression changes induced by Pb that were unique by day of differentiation but corresponded to a similar and human-relevant median benchmark concentration of 0.2 {micro}M for all days assessed. Overall, our findings provide evidence that transient Pb exposure during cardiomyocyte differentiation causes transcriptional changes in human cardiomyocytes that persist even after cessation of exposure, underscoring the need for further investigation into how Pb exposure may impact heart development and function.

pharmacology and toxicology↗

bioRxiv2026

Acute Exposure to Perfluorooctanoic Acid (PFOA) During Cardiomyogenesis disrupts Transcriptional and Electrophysiological Profiles in Differentiated Myocytes

The early developmental environment plays a critical role in the etiology of cardiovascular diseases (CVDs), but underlying molecular mechanisms are poorly understood. Exposure to per and polyfluoroalkyl substances (PFAS) are linked to various CVDs, but effects of developmental PFAS exposures on the human heart remain unclear. Using human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM), the objective of this study was to investigate the effects of PFAS exposure during cardiac differentiation on gene expression and function of cardiomyocytes. We exposed two hiPSC lines (one male and one female donor) to perfluorooctanoic acid (PFOA), a common and ubiquitous PFAS (0.05, 0.5, 5, 50, 100, 150, 200 M), followed by assessment of cellular number and pluripotency marker expression. PFOA exposure for 72 hours had no significant effects on hiPSC pluripotency, and modest inhibition of proliferation was observed only at the highest concentration. hiPSCs were then differentiated into ventricular cardiomyocytes in the continued presence or absence of PFOA (0, 0.5, 5, 50 M) using an established small molecules protocol. Optical mapping studies using voltage and calcium-sensitive dyes revealed dose and cell line-specific effects of PFOA on cardiomyocyte voltage and calcium dynamics that were still present 10 days after cessation of exposure. Patch clamping studies demonstrated small but significant reductions in repolarizing IKr currents with 5{micro}M PFOA exposure in cardiomyocytes from both donors. Using RNA-seq, we found that exposure to PFOA led to significant changes in transcriptional pathways related to lipids and lipoproteins in the female hiPSC-CM. In the male hiPSC-CM, we observed significant effects on developmental pathways and calcium homeostasis. Thus, we found that environmentally relevant PFOA exposure during cardiomyocyte differentiation affects the electrophysiological properties and transcriptome of hiPSC-CM even after cessation of exposure, with effects that differ by donor cell line. These findings provide direct experimental evidence that transient developmental exposure to PFOA can durably reprogram human cardiomyocyte function, supporting a developmental origin of PFAS-associated cardiovascular risk. Impact StatementThese studies demonstrate that exposure to environmentally relevant levels of PFOA during the differentiation of hiPSCs into cardiomyocytes alters cardiac gene expression and function, with effects that persist beyond cessation of exposure.

pharmacology and toxicology↗

bioRxiv2022

High Throughput Transcriptomics to Understand Chemical Drivers of Racial Disparities in Breast Cancer

BackgroundThe impact of chemical exposures on breast cancer progression is poorly characterized and may influence the development of more severe and aggressive subtypes. ObjectivesThere is a suite of toxicants, including metals, pesticides, and personal care product compounds, which are commonly detected at high levels in US Center for Disease Controls National Health and Nutrition Examination Survey (NHANES) chemical biomarker screens. To characterize the impact of these toxicants on breast cancer pathways, we performed high throughput dose-response transcriptomic analysis of toxicant exposed breast cells. MethodsWe treated non-tumorigenic mammary epithelial cells, MCF10A, with 21 chemicals at four doses (25nM, 250nM, 2.5{micro}M, 25{micro}M) for 48 hours. We conducted RNA-sequencing for these 408 samples, adapting the PlexWell plate-based RNA-sequencing method to analyze changes in gene expression resulting from these exposures. For each chemical, we calculated gene and biological pathway specific benchmark doses using BMDExpress2, identifying differentially expressed genes and generating the best fit benchmark dose models for each gene. We employed enrichment testing to test whether each chemicals upregulated or downregulated genes were over-represented in a biological process or pathway. We contextualized benchmark doses relative to human population biomarker concentrations in NHANES. ResultsOverall, significant changes in gene expression varied across doses of each chemical and benchmark dose modeling revealed dose-responsive alterations of thousands of different genes. Comparison of benchmark data to NHANES chemical biomarker concentrations indicated an overlap between actual exposure levels and levels sufficient to cause a gene expression response. Enrichment and cell deconvolution analyses showed benchmark dose responses correlated with changes in cancer and breast cancer related pathways, including induction of basal-like characteristics for some chemicals, including p,p-DDE, lead, copper, and methyl paraben. DiscussionThese analyses revealed that these 21 chemicals induce significant changes in pathways involved in breast cancer initiation and progression at human exposure relevant doses.

cancer biology↗