In 2011, Neurotar pioneered in vivo two-photon brain imaging in mice as a service for preclinical drug development.
Since then, we have expanded our service portfolio to multiple applications and started imaging in the brain of awake head-fixed mice in our proprietary Mobile HomeCage. Below we explain what two-photon imaging is, how it compares to conventional drug development methods, and list different types of services offered at Neurotar.
Two-photon imaging in a nutshell
Two-photon imaging (a.k.a two-photon microscopy) acquires high-resolution images of living cells and organelles by using the low-energy infra-red laser light. The infra-red light penetrates deep into a living animal’s brain without damaging it. This technology allows visualizing individual cells (and even sub-cellular organelles) in their natural undisturbed environment. Since two-photon microscopy is non-invasive, it allows re-examining the same experimental animal (and precisely the same cellular ensemble) over several days, weeks, or months. This yields an unmatched wealth of information on disease progression and drug action dynamics. Besides that, using the same animal as its own control greatly increases the statistical significance of the results and allows reducing the group size.
Two-photon microscopy in technical terms
Two-photon microscopy (also known as Multiphoton Excitation Laser Scanning Microscopy) relies on the phenomenon of simultaneous absorption of two infra-red photons by a fluorophore. The latter is usually a fluorescent protein, synthetic dye, or tissue’s own autofluorescent component. Non-linear summation of two infra-red photons’ energy results in excitation of the fluorophore, which emits a photon in the visible spectrum. Since the likelihood of coincident absorption of two photons is strictly limited in space, only fluorescent molecules that are located exactly in the focal point emit visible photons. The emitted photons are collected by sensitive photomultiplier tubes. The pulsed infra-red laser scans point-by-point through the plane of interest (and plane by plane, stacking two-dimensional XY images into a Z-stack by shifting focus in the vertical direction). Finally, dedicated computer software combines the data into sharply focused 2D images and, eventually, into a reconstructed 3D volumetric image.
Benefits of Neurotar’s in vivo two-photon imaging services
Neurotar offers in vivo two-photon imaging as a service to the pharmaceutical and biotechnological companies. Our services are usually deployed at the lead selection or lead optimization stages of preclinical drug development.
How do our services compare to conventional preclinical drug development methods? Conventional in vitro microscopy offers excellent resolution (tens to hundreds of nanometers), but the results obtained on dissociated cells or fixed tissue sections have limited relevance. Conventional in vivo imaging offers maximal relevance: it allows analyzing the brain of the same living animal repeatedly over time (milliseconds to weeks or months). However, its spatial resolution is severely limited.
Neurotar’s in vivo microscopy combines the benefits of both techniques and avoids their shortcomings. It yields high relevance data (obtained from a live animal) with high resolution (nanometer scale). We follow the disease progression and effects of treatments longitudinally and with sub-cellular resolution. Besides that: we perform microscopic imaging in the brain of anesthetized mice (in vivo) as well as in the brain of awake behaving mice (in vigilo).
Advantages of in vivo two-photon microscopy
Neurotar’s in vivo two-photon imaging service portfolio
Follow the links below to learn about our services in detail.
- Trans-BBB pharmacokinetics
- Blood-brain barrier integrity
- Dendritic spine turnover
- Microglial dynamics
- Abeta plaques dynamics
- Tau tangles dynamics
- Calcium signaling
- Mitochondrial fragmentation
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