UCSF

Many tissue-engineering approaches for repair and regeneration involve transplants between species. Yet a challenge is distinguishing donor versus host effects on gene expression. This study provides a simple molecular strategy to quantify species-specific contributions in chimeras and xenografts. Species-specific primers for reverse transcription quantitative real-time PCR (RT-qPCR) were designed by identifying silent mutations in quail, duck, chicken, mouse and human ribosomal protein L19 (RPL19). cDNA from different pairs of species was mixed in a dilution series and species-specific RPL19 primers were used to generate standard curves. Then quail cells were transplanted into transgenic-GFP chick and resulting chimeras were analyzed with species-specific primers. Fluorescence-activated cell sorting (FACS) confirmed that donor- and host-specific levels of RPL19 expression represent actual proportions of cells. To apply the RPL19 strategy, we measured Runx2 expression in quail-duck chimeras. Elevated Runx2 levels correlated with higher percentages of donor cells. Finally, RPL19 primers also discriminated mouse from human and chick. Thus, this strategy enables chimeras and/or xenografts to be screened rapidly at the molecular level.