![]() ![]() The method relies on the usage of three independent electrodes that upon an easy and highly reliable re-orientation of the electrode's positions and polarities results in a much improved accessibility to embryos in utero and a more efficient electric-field distribution, allowing a largely consistent expression of the genes of interest in the hippocampus, visual cortex, motor cortex and, for the first time to our knowledge, Purkinje cells in the cerebellum. Here, we present an innovative IUE configuration that allows simple and highly consistent transfection at various brain locations. Indeed, although IUE has tremendous potentialities in targeting all cell populations in brain areas deriving from progenitors lining the walls of the ventricular system, the steric inaccessibility of embryos in utero to a tilted forceps-type electrode may have made it difficult or impossible to practically target theoretically attainable regions 6, 17. This possibly indicates that reliability and consistency of IUE transfection was not straightforward for brain areas other than the somatosensory cortex. Notably, in the same timeframe the number of publications on the somatosensory cortex raised to 35 ( Supplementary Fig. However, notwithstanding the great scientific interest on both these brain regions, only two other articles for the hippocampus 12, 13 and visual cortex 15, 16 appeared in the first 6 years following their initial publications. Moreover, electroporation of the visual cortex was achieved in 2005 by orienting the forceps-type electrode along the antero-posterior axes 14. 13)-was obtained by orienting the forceps-type electrode in the medio-lateral axes. 8) and methodologically detailed in 2005 (ref. In particular, specific electroporation of the hippocampus-first described in 2001 (ref. In parallel, as the first description, several investigators have developed IUE for gene targeting of other brain regions by tilting the extra-uterine paddle electrodes and orienting the position of the electric field along different axes 1, 2, 11. Since then, owing to the simplicity and reliability of the procedure, the number of publications with IUE aiming at the somatosensory cortex has increased exponentially ( Supplementary Fig. IUE was first described in 2001 by three independent reports as a means to achieve targeted gene expression in the developing parietal (somatosensory) cortex of the rodent in vivo 8, 9, 10. Gene expression in neurons persists for a long time postnatally, and co-electroporation of fluorescent reporter genes enables visualization of targeted cells across development 5, 7. With expertize, ~70–90% of born pups expresses the transfected plasmid appropriately 8. ![]() Therefore, negatively charged DNA drifts towards the anode in the electric field, actively penetrating into the cell cytoplasm and allowing selective transfection of the neurogenic regions. The electric shocks destabilize the structure of the lipophilic cell membrane and induce the formation of transient electropores. Current delivery is facilitated by extra-uterine forceps-type paddle electrodes, which contribute to physically holding the uterus and the yolk sac containing the embryo. Transfection of neural progenitors of the brain area of interest is achieved by microinjection of plasmid DNA solution into the lumen of the ventricular system, followed by manually directing electrical pulses to the relevant neurogenic tissue. Depending on the locations of the different progenitors in the neurogenic epithelia and on the embryonic stage, this results in a spatially and temporally restricted neuronal population carrying the gene of interest 1, 2, 3, 4, 5, 6, 7. This technique takes advantage of the fact that by targeting neural progenitors at the epithelium of the ventricular system, one can address specific populations of newborn neurons that will migrate to the various brain areas. In utero electroporation (IUE) is a simple and quick procedure to efficiently perform in vivo genetic manipulation of specific cell types at different brain locations 1, 2. ![]()
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