# Deciphering the Cellular Effects of Strontium Chloride and Potassium Carbonate on Induced Pluripotent Stem Cells and Their Derivative Cardiomyocytes

## TL;DR

This study shows that toothpaste ingredients strontium chloride and potassium carbonate can harm stem cells and heart cells in a dose-dependent way, raising safety concerns.

## Contribution

The study is the first to demonstrate the cytotoxic and arrhythmogenic effects of SrCl2 and K2CO3 on iPSCs and iPSC-derived cardiomyocytes.

## Key findings

- Both compounds reduced iPSC proliferation and viability in a dose- and time-dependent manner.
- iPSC-derived cardiomyocytes showed downregulated cardiac genes and disrupted beating activity.
- Higher concentrations of the compounds caused increased cell death and impaired cardiac function.

## Abstract

Background/Objectives: Toothpaste ingredients such as strontium chloride (SrCl2) and potassium carbonate (K2CO3) are recognized for their desensitizing and remineralizing effects but may be absorbed through the oral mucosa. Their potential cytotoxic and cardiotoxic properties, however, remain inadequately characterized. Here, we investigated the effects of SrCl2 and K2CO3 on mouse-induced pluripotent stem cells (iPSCs) and iPSC-derived cardiomyocytes (iPSC-CMs). Methods: Cells were exposed to varying concentrations of each compound for up to 72 h. Real-time cell analysis (xCELLigence RTCA Cardio system) was used to assess proliferation, and flow cytometry was used to evaluate cell viability. Functional properties of iPSC-CMs were examined using multi-electrode array (MEA) recordings and xCELLigence-based impedance measurements. Cardiac marker expression was examined via immunofluorescence and quantitative RT-PCR. Results: Both SrCl2 and K2CO3 affected iPSC proliferation and reduced viability in a dose- and time-dependent manner, accompanied by altered embryoid body (EB) morphology and increased cell death. In iPSC-CMs, both compounds downregulated key cardiac genes and disrupted spontaneous beating activity, with effects intensifying at higher concentrations. Conclusions: These results demonstrate that SrCl2 and K2CO3 induced dose-dependent cytotoxic and arrhythmogenic effects on iPSCs and iPSC-CMs. At elevated concentrations, these compounds impair iPSC-CM function and may pose safety concerns upon chronic exposure. Further mechanistic and long-term in vivo studies are warranted to assess their potential cardiotoxic risk in consumer oral care products.