Mouse Ear Irradiation Model
We have developed equipment, techniques and protocols that allow us to irradiate a mouse ear using the charged-particle microbeam. Shown here is a custom designed holder to position the flattened mouse ear over the microbeam port
The ear of a mouse, measuring approximately 13 mm in both length and width and with an average thickness of 250 µm, can be used for radiation-induced bystander studies in vivo with our 3-MeV proton microbeam, which has a range of 134 µm. It is possible to irradiate a small area of the mouse ear and investigate bystander effects in non-targeted regions.
- For microbeam experiments, cells along a 6 mm line of a C57BL/6 mouse ear are irradiated with 3 MeV proton beam (~12.5 keV/µm, range 134 µm) with a diameter of ~ 35 µm
- Sham-irradiated animal served as controls
- 30 min after irradiation tissues were fixed, embedded and cut for analysis of radiation-induced biological endpoints such as the formation of radiation-induced DNA repair protein foci
- We found that compared to control, proton irradiation induces gammaH2AX foci formation. Strikingly, although the proton beam size was of ~ 35 µm in diameter the average length spanned by gammaH2AX positive cells was >150 µm.
- It can be speculated that microbeam proton irradiation induced DNA damage also in non-irradiated bystander cells that were in proximity to directly irradiated cells
If you are looking to do animal irradiations at RARAF, contact the RARAF staff before planning as any irradiation/handling protocols will be required to submit a research plan for approval to the Columbia University Institutional Animal Care and Use Committee (IACUC)