How neurons develop and acquire their morphology are questions of great importance for manipulating neuronal growth for biological and non-biological applications and for promoting neuronal regeneration post trauma. Our overall goal is to govern physical and molecular mechanisms that are involved in neuronal outgrowth and to develop technologies to promote and control the neuronal growth in vitro and in vivo. For the study we analyze a set of sensory neurons of a simple model system, the medicinal leech, which is ideal for studying neuronal outgrowth and regeneration at the level of single cells.

   Here we demonstrate a novel technology, a pneumatic capillary gene gun, for molecular modulations of genes in selected microscopic areas of tissue (in vivo and in vitro). The technology is based on fast and highly localized biolistic delivery of reagents into cells in internal layers of living leech embryos or in culture. We deliver nano- and micro- carrier particles to perform RNAi for silencing expression and to induce ectopic gene expression of axon guidance factors (netrin) in the skin of selected segments of leech embryos thus to affect the growth and distribution of the neurons (their branching rees). In order to evaluate quantitatively the effects we use image processing tools for 3D reconstruction.

   Previous studies have shown that mechanical tension plays a key role in stimulating axonal growth. We intend to use this novel delivery technology to introduce nanoparticles into neurons for mechanical manipulations and as a tool to detect the cytoskeleton dynamics.