TABLE 5.

Limitations in measuring intracellular pH.

Topic	Description
Limitations of the Current Techniques	Methods for measuring intracellular pH (pHi), including fluorescence pH probes, nuclear magnetic resonance, and pH microelectrodes, face challenges in accuracy, resolution, and potential cellular disruption. These limitations may hinder the ability to fully capture pHi variations, especially in complex in vivo conditions, potentially underestimating the pH discrepancy between tumor and normal cells
Intracellular and Inter-cell Variability	Within a single cell, pH levels can significantly differ across compartments like mitochondria, cytosol, and nucleus, and there’s notable variation among cells in the same tissue or culture, which current measurement methods may not fully capture
Effects of the Microenvironment	The cellular microenvironment, particularly in tumor tissues, can affect pHi in challenging ways to reproduce in vitro. Interactions between cells, the extracellular matrix, and soluble factors can significantly influence pHi, which standard culture conditions might not accurately replicate

Based on data from Loiselle and Casey (2010) and Jaworska and Malek (2021).