Identifying serum miRNA biomarkers for radiation exposure in hematopoietic humanized NSG-SGM3 mice.

BACKGROUND

Humans are commonly exposed to ionizing radiation. The conventional approach for estimating radiation exposure is to integrate physical and clinical measurements for optimizing the dose calculation. However, these methods have several limitations. The present study attempted to identify candidate microRNA (miRNA) biomarkers for radiation exposure in a hematopoietic humanized NSGS (hu-NSGS) mouse model.

METHODS

We grafted human CD34+ hematopoietic stem cells into NSG-SGM3 (NSGS) mice. The hu-NSGS mice underwent total body irradiation at doses of 2, 3, and 4 Gy. Tissues from the spleen, thymus, and lymph nodes of hu-NSGS mice were prepared to analyze levels of CD45+ and CD3+ T cells and CD 20+ B cells using flow cytometry and immunohistochemistry. Serum miRNAs were profiled using a digital multiplexed NanoString n-Counter.

RESULTS

The expression of 45 miRNAs was upregulated/downregulated hu-NSGS mice. The miRNAs hsa-mir-188-5p, hsa-let-7a-5p, hsa-mir-612, hsa-mir-671-5p, and hsa-mir-675-5p were highly radiation-responsive in irradiated hu-NSGS mice. When compared with control mice, radiation-exposed mice exhibited significant upregulated of hsa-let-7a-5p expression and significant downregulation of hsa-mir-188-5p expression.

CONCLUSIONS

Single miRNAs or combinations of hsa-mir-188-5p, hsa-let-7a-5p, hsa-mir-675-5p, hsa-mir-612, and hsa-mir-671-5p can be used as biomarkers for predicting the impact of radiation exposure. The current findings suggest the usefulness of hu-NSGS models for investigating radiation biomarkers.