5-Fluorouracil spares hemopoietic stem cells responsible for long-term repopulation

Area of Science:

• Hematology
• Stem Cell Biology
• Oncology

Background:

• 5-fluorouracil (5-FU) is a chemotherapy agent used in cancer treatment.
• Its effects on primitive stem cells (PSCs) and their long-term reconstituting ability are not fully understood.
• Assessing the impact of 5-FU on hematopoietic stem cells is crucial for understanding treatment side effects and recovery.

Purpose of the Study:

• To evaluate the long-term immunohemopoietic reconstituting ability of bone marrow after a single 5-fluorouracil (5-FU) treatment.
• To determine if 5-FU causes any deleterious effects on primitive stem cells (PSCs).
• To assess the radioresistance of 5-FU treated PSCs.

Main Methods:

• Bone marrow from 5-FU treated mice was mixed with untreated marrow and transplanted into lethally irradiated hosts.
• Functional ability was assessed by measuring donor-type hemoglobin (Hb) and glucosephosphate isomerase (GPI) in host erythrocytes and lymphocytes.
• A second repopulation round was stimulated with sublethal irradiation to test radioresistance.

Main Results:

• Bone marrow treated with 5-FU 1, 5, and 8 days prior to transplantation showed normal reconstituting ability.
• Normal reconstitution was maintained even with a tenfold reduction in marrow cell numbers after 5-FU treatment.
• 5-FU treated PSCs demonstrated radioresistance comparable to fresh marrow after sublethal irradiation.

Conclusions:

• A single administration of 5-FU does not compromise the long-term reconstituting ability or radioresistance of primitive stem cells (PSCs).
• PSCs surviving 5-FU treatment equally repopulated myeloid and lymphoid pathways, suggesting a common precursor.
• These findings indicate that PSCs are largely unaffected by a single 5-FU treatment, despite cellular concentration changes.