Luciferase reports Maternal Cell Chimerism

Are you a chimera? If in your body, some cells belong to your mother, you are a chimera of cells. Better, you are a living example of maternal cell microchimerism (MCM). In humans, maternal cells are present in the affected tissues of children with inflammatory myopathy, scleroderma, and neonatal lupus. The role of MCM in pregnancy and disease pathogenesis remains to be elucidated, and first of all, there is a need for background information (how many cells? how many tissues? how often?).

Su and colleagues from Tufts-New England Medical Center exploited reporter gene technology to adress some basic question: they bred female CMV-luciferase mice (from Xenogen) to wild type (WT) males. The WT offspring were sacrificed at various postnatal ages, multiple organs where microdissected and DNA was extracted for real-time PCR amplification of Luc transgene as a marker for maternally derived cells. Sensitivity was 1 to 2 transgenic cells per 100,000 WT cells. MCM was noted in 85% of mice and 45% of tissues assayed. Basically the authors draw a baseline for future mechanistic studies of MCM using qPCR amplification of a maternal genomic marker (the reporter). But what about in vivo imaging claimed in the title? They used such costly tecnique just for genotyping/phenotyping purposes (discarding luciferase-positive mice), this is a non-sense! Why not using PCR (all the paper is centered on PCR)?

Su, E.C., Johnson, K.L., Tighiouart, H., Bianchi, D.W. (2008). Murine Maternal Cell Microchimerism: Analysis Using Real-Time PCR and In Vivo Imaging. Biology of Reproduction DOI: 10.1095/biolreprod.107.063305