An efficient qPCR assay for the quantification of human cells in preclinical animal models by targeting human specific DNA in the intron of BRCA1

Background Precise quantification of grafted human cells in preclinical animal models such as non-human primates, rodents and rabbits is needed for the evaluations of the safety and efficacy of cell therapy. Quantitative PCR (qPCR) as a swift, sensitive and powerful assay is suitable for human cell quantification. However, it is a formidable challenge due to that the genome of non-human primates share more than 95% of similarity as human. Methods: In the present study, we developed a probe-based quantitative PCR (qPCR) assay for the quantification of human cells in preclinical animal models via targeting human specific DNA in the intron of BRCA1 (termed BRCA1-qPCR). The 5′ and 3′ end of BRCA1-qPCR probe was conjugated with FAM and non-fluorescent quencher-minor groove binder (NFQ-MGB), respectively. 1 µg of genomic DNA from human and preclinical animal models including rhesus monkeys, cynomolgus monkeys, New Zealand white rabbits, SD rats, C57BL/6 and BALB/c mice were used for determining the specificity and sensitivity of the BRCA1-qPCR assay. A calibration curve was generated by BRCA1-qPCR analysis of linearized plasmid containing targeted human specific DNA in BRCA1 . The BRCA1-qPCR assay was validated by analysis of 0.003%, 0.03% and 0.3% of human leukocytes mixed within murine leukocytes. Results The BRCA1-qPCR assay detected human DNA rather than DNA from tested species. The amplification efficiency of the BRCA1-qPCR assay was 95.4% and the linearity of the calibration curve was R 2 = 0.9997. The BRCA1-qPCR assay detected as low as 5 copies of human specific DNA and is efficient to specially amplify 30 pg human DNA in the presence of 1 µg of genomic DNA from tested species, respectively. The BRCA1-qPCR assay was able to quantify as low as 0.003% of human cells within murine leukocytes. Conclusion The BRCA1-qPCR assay is efficient for the quantification of human cells in preclinical animal models.