Challenges and limitations for live cell imaging in extreme cold

Area of Science:

• Cellular biology
• Microscopy
• Cryobiology

Background:

• Many ecosystems and polar organisms thrive in near-0 °C environments.
• Understanding cellular adaptations for survival in cold conditions is critical due to rapid polar warming.
• Current live-cell fluorescence microscopy methods are optimized for mammalian temperatures and often fail at low temperatures.

Purpose of the Study:

• To examine the challenges of live-cell fluorescence microscopy at near-0 °C.
• To discuss the breakdown of common imaging modalities and labeling strategies in cold conditions.
• To highlight the need for specialized microscopy platforms for studying cold-adapted life.

Main Methods:

• Review of conceptual, technical, and practical challenges in low-temperature microscopy.
• Analysis of how physicochemical changes at low temperatures affect probe behavior and imaging.
• Perspective on developing new biological questions addressable with cold-optimized microscopy.

Main Results:

• Standard microscopy tools and probes optimized for 37 °C perform poorly or yield biased data near 0 °C.
• Fluorophore photophysics, molecular motion, and membrane organization are fundamentally altered at low temperatures.
• Current temperature control strategies have trade-offs, and there's a need for improved fluorophore design and instrumentation.

Conclusions:

• Live-cell fluorescence microscopy at near-0 °C is a distinct operational regime, not merely an extension of conventional methods.
• Developing robust tools for cold conditions is essential for studying cold-adapted organisms and ecosystems.
• Further research is needed in fluorophore design, instrument engineering, and quantitative standards for low-temperature imaging.