Deep tissue imaging and optical windows

It is well known that the in vivo measure of optical (fluorescent and bioluminescent) reporters is hampered by tissue absorption at wavelenghts minor than 600 nm. Today, the most important trend to minimize tissue absorption is to design new red-shifted reporters and even infrared reporters. Another complementary approach is to "window" some tissue and gain access to desired cells. Sometimes this could appear very cruel, like in case of the skin flap approach proposed by Huang and collaborators in 2007. Now, a new eclectic approach is presented by Stephan Speier et colleagues in the May issue of Nature Medecine.

In their technical report, the swedish scientists from Karolinska, isolated pancreatic islets from transgenic mice expressing enhanced GFP under control of the rat insulin-1 promoter, then transplanted and engrafted the islets in the anterior chamber of the eye in order to noninvasively image vascularization, beta cell function and death at cellular resolution (microscope and confocal scanner from Leica Microsystem). In a few words, the researcher used the cornea as a natural body window that has the further advantage of being an immune-privileged site. The eye window and more classic skin windows protocols are available at Nature protocols

  • Speier, S., Nyqvist, D., Cabrera, O., Yu, J., Molano, R.D., Pileggi, A., Moede, T., Köhler, M., Wilbertz, J., Leibiger, B., Ricordi, C., Leibiger, I.B., Caicedo, A., Berggren, P. (2008). Noninvasive in vivo imaging of pancreatic islet cell biology. Nature Medicine, 14(5), 574-578. DOI: 10.1038/nm1701
  • Huang, Q., Acha, V., Yow, R., Schneider, E., Sardar, D.K., Hornsby, P.J. (2007). Bioluminescence measurements in mice using a skin window. Journal of Biomedical Optics, 12(5), 054012. DOI: 10.1117/1.2795567