Tritium contamination of hematopoietic stem cells alters long-term hematopoietic reconstitution

Abstract

Purpose: In vivo effects of tritium contamination are poorly documented. Here, we study the effects of tritiated Thymidine ([³H] Thymidine) or tritiated water (HTO) contamination on the biological properties of hematopoietic stem cells (HSC).

Materials and methods: Mouse HSC were contaminated with concentrations of [³H] Thymidine ranging from 0.37–37.03 kBq/ml or of HTO ranging from 5–50 kBq/ml. The biological properties of contaminated HSC were studied in vitro after HTO contamination and in vitro and in vivo after [³H] Thymidine contamination.

Results: Proliferation, viability and double-strand breaks were dependent on [³H] Thymidine or HTO concentrations used for contamination but in vitro myeloid differentiation of HSC was not affected by [³H] Thymidine contamination. [³H] Thymidine contaminated HSC showed a compromised long-term capacity of hematopoietic reconstitution and competition experiments showed an up to two-fold decreased capacity of contaminated HSC to reconstitute hematopoiesis. These defects were not due to impaired homing in bone marrow but to an initial decreased proliferation rate of HSC.

Conclusion: These results indicate that contaminations of HSC with doses of tritium that do not result in cell death, induce short-term effects on proliferation and cell cycle and long-term effects on hematopoietic reconstitution capacity of contaminated HSC.

Keywords:

• hematopoietic stem cells
• contamination by tritiated thymidine or tritiated water
• hematopoietic reconstitution

Acknowledgements

We acknowledge Pierre Fouchet and Zahra Kadri for helpful discussions. We are grateful to the staff of the iRCM animal facility for excellent support in mouse studies, to Benjelloun H, Deschamps N and Baijer J of the iRCM cytometry platform for excellent support in FACS and cell sorting experiments and to Lahaye JB of the iRCM irradiation platform for the excellent support in animal irradiation. Fabio Di Giacomo and Vilma Barroca are supported by fellowships from Marie Curie Research fellowship from the EU fp6 program ‘Eurythron’ MRTN-CT-2004-005499 and from Inserm. This project was supported by grants from EDF (Electricité de France), Association pour la Recherche sur le Cancer (ARC, 3710), Inserm and Commissariat à l'Energie Atomique (CEA)/Direction des Sciences du Vivant (DSV).

Declaration of interest:

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.