Nanoparticle-mediated delivery of placental gene therapy via uterine artery catheterization in a pregnant rhesus macaque

Abstract

Nanoparticles offer promise as a mechanism to non-invasively deliver targeted placental therapeutics. Our previous studies utilizing intraplacental administration demonstrate efficient nanoparticle uptake into placental trophoblast cells and overexpression of human IGF1 (hIGF1). Nanoparticle-mediated placental overexpression of hIGF1 in small animal models of placental insufficiency and fetal growth restriction improved nutrient transport and restored fetal growth. The objective of this pilot study was to extend these studies to the pregnant nonhuman primate and develop a method for local delivery of nanoparticles to the placenta via maternal blood flow from the uterine artery. Nanoparticles containing hIGF1 plasmid driven by the placenta-specific PLAC1 promoter were delivered to a mid-gestation pregnant rhesus macaque via a catheterization approach that is clinically used for uterine artery embolization. Maternal-fetal interface, fetal and maternal tissues were collected four days post-treatment to evaluate the efficacy of hIGF1 treatment in the placenta. The uterine artery catheterization procedure and nanoparticle treatment was well tolerated by the dam and fetus through the four-day study period following catheterization. Nanoparticles were taken up by the placenta from maternal blood as plasmid-specific hIGF1 expression was detected in multiple regions of the placenta via in situ hybridization and qPCR. The uterine artery catheterization approach enabled successful delivery of nanoparticles to maternal circulation in close proximity to the placenta with no concerns to maternal or fetal health in this short-term feasibility study. In the future, this delivery approach can be used for preclinical evaluation of the long-term safety and efficacy of nanoparticle-mediated placental therapies in a rhesus macaque model.

Keywords: Gene therapy; IGF1; Macaque; Nanoparticles; Placenta.

Fig. 1.. Evaluation of acute maternal and fetal responses to uterine artery catheterization.

A. Image of fluoroscopy-guided catheterization of the uterine artery. The arrows indicate the catheter placement in the femoral artery, the tip of the catheter at the uterine artery, and the fetal spine relative to the uterine artery. B. Fetal heart rate (HR) in beats per minute (bpm) at −7 days prior to treatment, at the time of the procedure and 4 days post-treatment. C. Levels of estradiol and progesterone in maternal circulation; one serum sample was assayed per timepoint. D. Complete blood count analysis of maternal white blood cells, red blood cells, and platelet levels as evaluated by complete blood cell count. The reference interval for each parameter for non-pregnant rhesus females is indicated by dashed lines.

Fig. 2.. Detection of hIGF1 in the nanoparticle-treated placenta.

A. Gross images of the placental discs. Each disc was dissected into six regions using a grid pattern to evaluate RNA and protein expression. A center cut (tissue region indicated by the dashed lines) was collected for histopathological analysis. B. In situ hybridization of tissues pieces within the primary placenta disc. C. In situ hybridization of decidua, cytokeratin immunohistochemistry of serial section and merged image demonstrating trophoblast localization of ISH. D. Relative gene expression of hIGF1 in control, untreated placenta, directly injected placenta and the placenta that received nanoparticles via uterine artery (UA) delivery as determined by qPCR.