Multi-isotope imaging mass spectrometry quantifies stem cell division and metabolism

Area of Science:

• Cell Biology
• Biophysics
• Biochemistry

Background:

• Stable isotope labeling in mass spectrometry is crucial for studying biological dynamics.
• Current methods are limited to bulk tissues or cells, lacking spatial resolution.
• The immortal strand hypothesis proposes asymmetric DNA segregation in stem cells for genetic stability.

Purpose of the Study:

• To develop and apply multi-isotope imaging mass spectrometry (MIMS) for high-resolution stable isotope analysis.
• To investigate the 'immortal strand hypothesis' using MIMS in vivo.
• To demonstrate the broad applicability of MIMS in diverse biological systems.

Main Methods:

• Development of multi-isotope imaging mass spectrometry (MIMS) with submicrometre resolution.
• Stable isotope labeling (e.g., (15)N-thymidine) in mice, Drosophila, and human hematopoietic cells.
• Application of pulse-chase experiments to track label dynamics in proliferating cells.

Main Results:

• MIMS enabled visualization and quantification of stable isotope incorporation at the submicrometre level.
• No evidence for the immortal strand hypothesis was found in mouse intestinal crypt cells; random strand segregation was observed.
• MIMS demonstrated utility in analyzing lipid turnover in Drosophila and human hematopoiesis.

Conclusions:

• MIMS is a powerful, broadly applicable technique for high-resolution biological research.
• The immortal strand hypothesis is not supported by evidence from this study.
• MIMS provides novel insights into cellular dynamics and genetic stability.