RESUMO
Objective To establish a quantitative polymerase chain reaction(PCR)method for the analysis of human-derived SRY DNA in mouse tissues,and to study the tissue distribution of human umbilical cord mesenchymal stem cells(HUCMSCs)in immunodeficient NOG mice after a single intravenous injection.Methods We established a quantitative PCR method for the analysis of human SRY DNA in mouse tissues,and validated the standard curve,linear range,accuracy,precision,and stability.Thirty-six NOG mice(18 male,18 female)were administered 3.5×107 HUCMSCs/kg by single intravenous injection.Six mice were then anesthetized and dissected after blood collection(EDTA anticoagulation)at 6,12,24,and 72 h,and at 1 and 2 weeks,respectively.DNA was extracted from lung,kidney,heart,liver,brain,spinal cord,stomach,small intestine,fat,skin,spleen,testis,uterus,and ovary tissues,and the distribution of HUCMSCs in each tissue was determined by the validated quantitative PCR method for detecting the human-derived SRY gene in mouse tissues.In addition,18 NOG mice(9 male,9 female)were divided into control(n = 6)and treatment groups(n = 12)injected intravenously with 0.9%sodium chloride and 3.5×107 cells/kg,respectively.Acute toxic reactions were observed during the administration period,and four animals were dissected at 72 h and at 2 and 4 weeks after administration to observe the gross organs.Mitochondrial protein expression was detected in paraffin sections of lung tissues by immunohistochemistry to analyze the colonization of HUCMSCs in lung tissues.Results The established RT-qPCR method for human-derived SRY DNA in mouse tissues met the validation criteria for each index.After a single intravenous injection in NOG mice,HUCMSCs were mainly distributed in the lungs and blood within 1 week after administration,with higher concentrations in lung tissues than in blood.The concentrations of HUCMSCs in lung tissue and blood remained relatively stable within 6～24 h and 6～72 h,respectively,and then decreased over time.The distribution of HUCMSCs in other tissues was not measured at all sampling points.The colonization result showed that HUCMSCs were detected in lungs 72 h after intravenous injection,but not at 2 and 4 weeks.No obvious acute toxicity was observed in NOG mice after single intravenous administration of HUCMSCs.Conclusions The above method for analyzing the distribution of HUCMSCs in mouse tissue is reliable and feasible.HUCMSCs were mainly distributed in lung and blood in NOG mice within 1 week after a single intravenous injection,and mainly colonized lung tissue at 72 h.A single intravenous administration of HUCMSCs has a good safety profile.