Effect of hyperthyroidism on haemopoietic stem cell kinetics in mice

Area of Science:

• Hematology
• Endocrinology
• Stem Cell Biology

Background:

• Thyroid hormones play a crucial role in regulating various physiological processes.
• The impact of thyroid hormones on hematopoietic stem cells (HSCs) requires further elucidation.

Purpose of the Study:

• To investigate the effect of dried thyroid gland (TH) administration on hematopoietic colony-forming units (CFUs) in mice.
• To assess changes in HSCs' proliferative activity and bone marrow/spleen cellularity following TH treatment.

Main Methods:

• Mice were fed dried thyroid gland (TH) for 21 days, with observations continuing for 13 days post-treatment.
• Colony-forming units (CFUs) in DNA synthesis were quantified after hydroxyurea (HU) treatment.
• Nucleated cell counts in bone marrow and spleen, peripheral blood cell counts, erythrocyte counts, and hematocrit values were analyzed.

Main Results:

• TH treatment led to a significant increase in both splenic and bone marrow CFUs, with elevated numbers persisting post-treatment.
• Nucleated cell numbers in bone marrow and spleen increased concurrently with CFU counts.
• Peripheral blood showed an increase in leukocytes, while erythrocytes and hematocrit remained unchanged. Proliferative activity of CFUs peaked within the first week of TH administration.

Conclusions:

• Thyroid hormones (TH) exhibit a rapid stimulatory effect on the hematopoietic stem cell compartment.
• Increased CFU numbers and proliferative activity suggest a direct or indirect influence of TH on HSCs.
• The involvement of humoral factors in mediating the stimulatory effects of TH on HSCs is proposed.