An optical Doppler tomography (ODT) system that permits imaging of fluid flow velocity in highly scattering media is described. ODT combines Doppler velocimetry with the high spatial resolution of low-coherence optical interferometry to measure fluid flow velocity at discrete spatial locations. Tomographic imaging of particle flow velocity within a circular conduit submerged 1 mm below the surface in a highly scattering phantom of Intralipid is demonstrated.

We describe a neuro-optical microfluidic platform for studying injury and subsequent regeneration of individual mammalian axons. This platform consists of three components integrated on an inverted microscope, which include a compartmentalized neuronal culture microfluidic device, a femtosecond laser to enable precise axotomy, and a custom built mini cell culture incubator for continuous long term observation of post injury events. We demonstrate the unique capabilities of the platform by injuring individual central and peripheral nervous system axons and monitoring the post injury sequence of events from initial degeneration to subsequent regeneration. This platform will enable study and understanding of neuronal response to injury that is currently not possible with conventional cell culture platform and tools.

Graphical AbstractHighlights d Distinct types of gliomas interact with different sets of brain cells d Glioma cells use extracellular vesicles to achieve the gliomabrain-cell crosstalk d EV-mediated communication alters neuronal activity in the labeled neurons SUMMARY Emerging evidence suggests that crosstalk between glioma cells and the brain microenvironment may influence brain tumor growth. To date, known reciprocal interactions among these cells have been limited to the release of paracrine factors. Combining a genetic strategy with longitudinal live imaging, we find that individual gliomas communicate with distinct sets of non-glioma cells, including glial cells, neurons, and vascular cells. Transfer of genetic material is achieved mainly through extracellular vesicles (EVs), although cell fusion also plays a minor role. We further demonstrate that EV-mediated communication leads to the increase of synaptic activity in neurons. Blocking EV release causes a reduction of glioma growth in vivo. Our findings indicate that EV-mediated interaction between glioma cells and non-glioma brain cells alters the tumor microenvironment and contributes to glioma development.