Abstract
Low birth weight is associated with both short term problems and the fetal programming of adult onset diseases, including an increased risk of obesity, diabetes and cardiovascular disease. Placental insufficiency leading to intrauterine growth restriction (IUGR) contributes to the prevalence of diseases with developmental origins. Currently there are no therapies for IUGR or placental insufficiency. To address this and move towards development of an in utero therapy, we employ a nanostructure delivery system complexed with the IGF-1 gene to treat the placenta. IGF-1 is a growth factor critical to achieving appropriate placental and fetal growth. Delivery of genes to a model of human trophoblast and mouse placenta was achieved using a diblock copolymer (pHPMA-b-pDMAEMA) complexed to hIGF-1 plasmid DNA under the control of trophoblast-specific promoters (Cyp19a or PLAC1). Transfection efficiency of pEGFP-C1-containing nanocarriers in BeWo cells and non-trophoblast cells was visually assessed via fluorescence microscopy. In vivo transfection and functionality was assessed by direct placental-injection into a mouse model of IUGR. Complexes formed using pHPMA-b-pDMAEMA and CYP19a-923 or PLAC1-modified plasmids induce trophoblast-selective transgene expression in vitro, and placental injection of PLAC1-hIGF-1 produces measurable RNA expression and alleviates IUGR in our mouse model, consequently representing innovative building blocks towards human placental gene therapies.
Highlights
Inappropriate placental development affecting up to 6% of all pregnancies is associated with multiple pathologies and accounts for a 75% of all cases of intra-uterine growth restriction [1]
NP-CyP19a-human IGF-1 (hIGF-1) placentas showed evidence of morphological disturbance with disorganization in the labyrinth zone (Fig 5D) and expansion of the junctional zone as demonstrated by the altered ratio of labyrinth to junctional zone (Fig 5E), as shown previously in some transgenic strains [25]. This is the first study to successfully deliver a human transgene into a mouse placenta in vivo and human trophoblast in vitro using non-viral mechanisms
We demonstrate that delivery of IGF-1 via the nanoparticle was able to express sufficient transgene to restore normal fetal growth in a mouse model of placental insufficiency and fetal growth restriction
Summary
Inappropriate placental development affecting up to 6% of all pregnancies is associated with multiple pathologies and accounts for a 75% of all cases of intra-uterine growth restriction [1]. Previous experiments using adenovirus-mediated gene transfer to the placenta modulates placental function and fetal growth in vivo [7, 8] These studies have shown that transgene expression is minimal but still occurs in the fetus or mother following placental delivery of gene therapy [9]. The development of polymer-based biodegradable nanoparticles [12] permits non-viral gene delivery leading to enhanced cell and organ function. Purified plasmid DNA containing a sequence for IGF-1 is complexed by poly(2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA), a tertiary amine that acts as a weak base capable of being protonated at biological pH [15] Together these co-polymers provide a non-viral nanoparticle alternative for gene transfer into the placenta. In a mouse model of surgicallyinduced placental insufficiency, we are able to detect expression of human IGF-1 in placenta and maintenance of fetal growth
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