The expression of placental soluble fms-like tyrosine kinase 1 in mouse placenta varies significantly across different litters from normal pregnant mice

Objective: Gene expression studies often pool tissues from multiple placentas when using animal models of preeclampsia without accounting for the potential confounders of litter origin or pup sex. We aimed to determine whether placental gene expression differs based on sex or litter. Methods: We examined the differential expression of soluble fms-like tyrosine kinase 1 (Flt-1) using 35 pups from six normal pregnant mice. Results: Expression of sFlt-1 (p = 0.003) was significantly different between litters but not between sexes (p = 0.17). Conclusions: These findings highlight the importance of adequate sampling from multiple litters in expression studies when using animal models in clinical research.