Mouse beta cell proliferation is inhibited by thymidine analogue labelling

Area of Science:

• Endocrinology
• Cell Biology
• Regenerative Medicine

Background:

• Long-term labeling with halogenated thymidine analogues is a standard method to assess beta cell proliferation in vivo.
• This technique is used to quantify beta cell expansion during regeneration and to determine the duration of postmitotic quiescence.

Purpose of the Study:

• To investigate the hypothesis that long-term thymidine analogue administration negatively impacts beta cell proliferation.
• To determine if this labeling method provides an accurate assessment of beta cell regenerative capacity.

Main Methods:

• Neonatal, young, and adult mice received thymidine analogues for 7-14 days via intraperitoneal injection or drinking water.
• Beta cell proliferation was assessed by Ki67 and phosphorylated histone H3 expression and nucleotide analogue incorporation.
• Proliferation markers and analogue incorporation were compared between treated and control groups, and after analogue washout.

Main Results:

• Long-term thymidine analogue administration significantly reduced the percentage of proliferating beta cells (Ki67+, phosphorylated histone H3+) compared to controls.
• Beta cell proliferation returned to normal levels after the cessation of analogue administration (washout).
• Pre-labeling with one thymidine analogue diminished the subsequent incorporation of a different analogue, indicating an inhibitory effect.

Conclusions:

• Long-term labeling with halogenated thymidine analogues is a biased method for studying beta cell proliferation.
• The technique underestimates the true proliferation and re-division potential of mouse beta cells.
• This finding necessitates a critical re-evaluation of previous studies relying on this method for assessing beta cell regeneration.