A Novel Surgical Approach for Intratracheal Administration of Bioactive Agents in a Fetal Mouse Model

Abstract

Prenatal pulmonary delivery of cells, genes or pharmacologic agents could provide the basis for new therapeutic strategies for a variety of genetic and acquired diseases. Apart from congenital or inherited abnormalities with the requirement for long-term expression of the delivered gene, several non-inherited perinatal conditions, where short-term gene expression or pharmacological intervention is sufficient to achieve therapeutic effects, are considered as potential future indications for this kind of approach. Candidate diseases for the application of short-term prenatal therapy could be the transient neonatal deficiency of surfactant protein B causing neonatal respiratory distress syndrome 1,2 or hyperoxic injuries of the neonatal lung Generally, an important advantage of prenatal gene therapy is the ability to start therapeutic intervention early in development, at or even prior to clinical manifestations in the patient, thus preventing irreparable damage to the individual. In addition, fetal organs have an increased cell proliferation rate as compared to adult organs, which could allow a more efficient gene or stem cell transfer into the fetus. Furthermore, in utero gene delivery is performed when the individual's immune system is not completely mature. Therefore, transplantation of heterologous cells or supplementation of a non-functional or absent protein with a correct version should not cause immune sensitization to the cell, vector or transgene product, which has recently been proven to be the case with both cellular and genetic therapies 7 .In the present study, we investigated the potential to directly target the fetal trachea in a mouse model. This procedure is in use in larger animal models such as rabbits and sheep 8, and even in a clinical setting 9 , but has to date not been performed before in a mouse model. When studying the potential of fetal gene therapy for genetic diseases such as CF, the mouse model is very useful as a first proof-of-concept because of the wide availability of different transgenic mouse strains, the well documented embryogenesis and fetal development, less stringent ethical regulations, short gestation and the large litter size.Different access routes have been described to target the fetal rodent lung, including intra-amniotic injection [10][11][12] , (ultrasound-guided) intrapulmonary injection 13,14 and intravenous administration into the yolk sac vessels 15,16 or umbilical vein 17 . Our novel surgical procedure enables researchers to inject the agent of choice directly into the fetal mouse trachea which allows for a more efficient delivery to the airways than existing techniques 18 . Video LinkThe video component of this article can be found at

Immunological Ignorance Allows Long-Term Gene Expression After Perinatal Recombinant Adeno-Associated Virus-Mediated Gene Transfer to Murine Airways

“…Fetal vector delivery by intraamniotic injection (60 ll of vector suspension) was performed as previously described (Carlon et al, 2010(Carlon et al, , 2012. Neonatal vector administration to the airways was performed by sniffing on day 3 postpartum.…”

A novel translational model for fetoscopic intratracheal delivery of nanoparticles in piglets

“…Different animal models have been described for intra‐uterine nanoparticles delivery into fetal lungs . Only larger animals, such as sheep, pig and primates, allow the fetoscopic route because of their comparable anatomical size as humans.…”

“…20 nm for rAAV), the substance it is dissolved in, usually saline, and its tropism. In the past we have already shown that the distribution of fluospheres was very comparable to that of rAAV2/6.2 delivery and subsequent gene expression in fetal mouse airways …”

“…Non‐injected control fetuses were processed the same way. Samples were processed for cryosectioning as described previously . Each lung sample was dissected into seven segments (i.e.…”

“…Previously, we demonstrated that direct intratracheal delivery of fluospheres and viral vectors to the lungs of fetal mice resulted in more efficient targeting of lung parenchyma compared to intra‐amniotic delivery . An efficient delivery route becomes even more important when upscaling to a large animal model, for example, pig.…”