Chrysanthi Samara

Large-scale in vivo femtosecond laser neurosurgery screen reveals small-molecule enhancer of regeneration

Discovery of molecular mechanisms and chemical compounds that enhance neuronal regeneration can lead to development of therapeutics to combat nervous system injuries and neurodegenerative diseases. By combining high-throughput microfluidics and femtosecond laser microsurgery, we demonstrate for the first time large-scale in vivo screens for identification of compounds that affect neurite regeneration. We performed thousands of microsurgeries at single-axon precision in the nematode Caenorhabditis elegans at a rate of 20 seconds per animal. Following surgeries, we exposed the animals to a hand-curated library of approximately one hundred small molecules and identified chemicals that significantly alter neurite regeneration. In particular, we found that the PKC kinase inhibitor staurosporine strongly modulates regeneration in a concentration- and neuronal type-specific manner. Two structurally unrelated PKC inhibitors produce similar effects. We further show that regeneration is significantly enhanced by the PKC activator prostratin.

Microfluidic in vivo screen identifies compounds enhancing neuronal regeneration.

Compound screening is a powerful tool to identify new therapeutic targets, drug leads, and elucidate the fundamental mechanisms of biological processes. We report here the results of the first in vivo small-molecule screens for compounds enhancing neuronal regeneration. These screens are enabled by the microfluidic devices we have developed for C. elegans. The devices enable rapid and repeatable animal immobilization which allows high-throughput and precise surgery. Following surgery, animals are exposed to the contents of a small-molecule library and assayed for neuronal regeneration. Using this screening method we have identified several compounds that enhance neural regeneration in vivo.

High-throughput in vivo genetic and drug screening using femtosecond laser nano-surgery, and microfluidics

We demonstrate microfluidic devices and imaging technologies for high-speed immobilization, cellular resolution imaging, and femtosecond laser micro-surgery of awake small-animals (C. elegans) for high-throughput in vivo genetic and drug screens on neural degeneration and regeneration.

High-throughput on-chip in vivo neural regeneration studies using femtosecond laser nano-surgery and microfluidics

In recent years, the advantages of using small invertebrate animals as model systems for human disease have become increasingly apparent and have resulted in three Nobel Prizes in medicine or chemistry during the last six years for studies conducted on the nematode Caenorhabditis elegans (C. elegans). The availability of a wide array of species-specific genetic techniques, along with the transparency of the worm and its ability to grow in minute volumes make C. elegans an extremely powerful model organism. We present a suite of technologies for complex high-throughput whole-animal genetic and drug screens. We demonstrate a high-speed microfluidic sorter that can isolate and immobilize C. elegans in a well-defined geometry, an integrated chip containing individually addressable screening chambers for incubation and exposure of individual animals to biochemical compounds, and a device for delivery of compound libraries in standard multiwell plates to microfluidic devices. The immobilization stability obtained by these devices is comparable to that of chemical anesthesia and the immobilization process does not affect lifespan, progeny production, or other aspects of animal health. The high-stability enables the use of a variety of key optical techniques. We use this to demonstrate femtosecond-laser nanosurgery and three-dimensional multiphoton microscopy. Used alone or in various combinations these devices facilitate a variety of high-throughput assays using whole animals, including mutagenesis and RNAi and drug screens at subcellular resolution, as well as high-throughput high-precision manipulations such as femtosecond-laser nanosurgery for large-scale in vivo neural degeneration and regeneration studies.