Application of Chorionic Villus Sampling to Longitudinal Studies in Pregnant Nonhuman Primate Models

The rhesus macaque (Macaca mulatta) is a valuable model for pregnancy research due to its physiological similarity to humans and the ability to conduct studies in a controlled environment. Our previous work used noninvasive imaging methods to assess placental hemodynamics across gestation with correlative tissue analysis post-delivery. Here, we expand access to longitudinal timepoints from ongoing pregnancies by obtaining placental biopsies using ultrasound-guided needle aspiration. This approach aligns with New Approach Methods (NAMs) and supports animal welfare by reducing the number of animals required. We describe a chorionic villus sampling (CVS) simulation model which facilitates training to gain proficiency in technical skills prior to performing the procedure in animals. We report outcomes from three rhesus macaques that underwent CVS three times between gestational days 40 to 106 (term: 165 days). Although biopsy samples are smaller than whole placenta, tissue yields were sufficient for multiple uses. We demonstrate 1) appropriate histology from aspirated samples, 2) good RNA quality and yield, and 3) the ability to isolate trophoblast organoids, a NAMs advancement that reduces the need for first-trimester surgical delivery. No adverse outcomes occurred following serial CVS procedures, supporting the use of this sampling to maximize animal utilization in longitudinal pregnancy studies.