Objective: Assessment of liver metabolism using blood samples was tested by comparison of cytochrome P450 (CYP) gene expression in paired liver and blood samples from 13 individuals.
Methods: Total RNA was isolated from percutaneous needle biopsies and blood collected simultaneously. Gene expression for CYP1A2, CYP1B1, CYP2E1 and CYP3A4 was studied using a real-time reverse-transcription polymerase chain reaction (RT-PCR) method.
Results: All CYP mRNA species were expressed in all liver biopsies but at varying levels. The highest and lowest levels of expression were observed for CYP2E1 and CYP1B1, respectively. The expression patterns differed between blood and liver. CYP1B1 was expressed in all blood samples at a 20% higher level than in the liver. CYP1A2, CYP2E1 and CYP3A4 were expressed in blood at 35- to 5,000-fold lower levels than in liver. None of the transcripts in blood showed any correlation with the expression in liver.
Conclusion: We conclude that blood cannot serve as a surrogate organ for assessment of the expression of the studied CYP genes in liver.