Photon Imager - In Actio
Conventional optical imaging instruments are too often limited to the quantification of a still signal, revealing the expression of a molecule at a given time only. Biological phenomena are always dynamic, and a single observation at a unique time point usually gives an incomplete information and can often lead to misinterpretation. With such 'photography'-like observations, the dynamics of 'fast' phenomena remains completely unaccessible. Before In Actio, in vivo molecular imaging with non invasive optical modalities had the following limitations:
- Imaging the animal during motion was not possible. Monitoring calcium activity in the brain during sleep and wake cycles or observing a bioluminescent signal in a contracting muscle could not be done non invasively in vivo.
- Anesthesia could be a time consuming step and a limit to the capacity of the imaging systems to have a high throughput
- Anesthesia could introduce a bias, disturb the physiology of the pathology model, or affect the signal expression
Being able to image non anesthetized, non sedated animals opens new possibilities that could not be imagined before.
The In Actio module records simultaneously the signal and a video of the animal under infra red lightning for co-registration.
Hence, the Photon Imager extends its imaging capabilities from a dynamic signal on an anesthetized animal, to a dynamic signal on a dynamic animal.
The In Actio modules gathers the following advantages, for protocols when there is no need for acquisition of the ventral or lateral sides of the animal:
- Physiological relevance: observe physiological or pathological phenomena free from disturbance.
- Reduced animal preparation: Anesthesia is not required any more.
- High throughput: Several animals can be imaged simultaneously, the procedure being quicker without anesthesia
Examples of acquisition are shown below with freely moving mice and fish.
Freely moving mouse with subcutaneous luminescent nanoparticules, imaged with a temporal resolution of 20 ms.
Fish with persistent luminescence nanoparticules.
In Actio imaging has the possibility to offer unprecedented flexibility in many different fields; one must keep in mind, however, that it is limited, for awake rodents, as acquisition of the back of the animal.
The applications below are listed as examples:
- Molecular approaches to behavioral studies. Ex: calcium flux during sleep and wake cycles
- Functional physiological studies, with calcium imaging during muscular contraction
- Biodistribution of therapeutic molecules at the subcutaneous tumor site in awake animals
Some of these applications are thoroughly described in the publication of Rogers et al: Non-invasive in vivo imaging of calcium signaling in mice,
PLoS ONE, 2(10): e974 (2007) (link)
Photon Imager - Optional modules