Measuring interstitial pH and pO2 in mouse tumors

Area of Science:

• Biomedical Engineering
• Cancer Research
• Microscopy Techniques

Background:

• Tumor microenvironment characterization is crucial for understanding cancer progression.
• Accurate measurement of interstitial pH and pO2 is essential for evaluating tumor hypoxia and acidity.
• Existing methods may lack the precision or sequential measurement capabilities for comprehensive analysis.

Purpose of the Study:

• To present a detailed protocol for measuring extravascular interstitial pH in mouse tumors.
• To describe a method for quantifying interstitial and microvascular partial pressure of oxygen (pO2) in tumors.
• To enable sequential measurement of both interstitial pH and pO2 within the same tissue samples.

Main Methods:

• Interstitial pH measurement using fluorescence ratio imaging microscopy (FRIM) with the pH-sensitive dye BCECF.
• Interstitial and microvascular pO2 measurement via oxygen-dependent phosphorescence quenching of albumin-bound palladium porphyrin.
• Sequential application of both pH and pO2 measurement techniques on identical tissue specimens.

Main Results:

• The protocol provides a reliable means to assess interstitial pH in mouse tumor models.
• The phosphorescence quenching method accurately quantifies oxygen levels in both interstitial space and tumor vasculature.
• Demonstrated feasibility of performing sequential pH and pO2 measurements on the same tumor tissue.

Conclusions:

• This protocol offers valuable tools for in-depth analysis of the tumor microenvironment.
• The combined pH and pO2 measurements enhance our understanding of tumor pathophysiology.
• These methods support further research into targeted cancer therapies and diagnostics.