Professor Ulf Ahlgren and his associates at the Umeå Center for Molecular Medicine (UCMM) have developed technology for biomedical imaging with optical projection tomography (OPT). Initially the method could only be used on relatively small preparations, but five years ago the scientists at Umeå were able to adapt the technology to study whole organs including the pancreas from adult mice. The present findings describe a further development of the OPT technology by going from ordinary visible light to the near-infrared spectrum. Near infrared light is light with longer wavelengths that can more easily penetrate tissue. Thereby, the developed imaging platform enables studies of considerably larger samples than was previously possible. This includes the rat pancreas, which is important because rats as laboratory animals are thought to be physiologically more similar to humans.
This adaptation, also able to image in near-infrared light, means that the researchers gain access to a broader range of the light spectrum, making it possible to study more and different cell types in one organ preparation. In the article the scientists exemplify the possibility of simultaneously tracking the insulin-producing islets of Langerhans as well as the autoimmune infiltrating cells and the distribution of blood vessels in a model system for type-1 diabetes.
Internationally, huge resources are being committed to the development of non-invasive imaging methods for study of the number of remaining insulin cells in patients with developing diabetes. Such methods would be of great importance as only indirect methods for this exist today. However, a major problem in these research undertakings is to find suitable contrast agents that specifically bind to the insulin producing cells of the pancreas to allow imaging. In this context, the developed Near Infrared — OPT technology can play an important role as it enables the evaluation of new contrast agents. It may also be used as a tool to calibrate the non-invasive read out by e.g. magnetic resonance imaging (MRI).
Near-infrared optical projection tomography enables the visualization of several cell types in large preparations. The image of a pancreas from a mouse with type-1 diabetes shows the insulin-producing islets of Langerhans in blue, blood vessels in red, and infiltrating autoimmune cells that break down the insulin-producing cells in green. (Credit: Image courtesy of Umeå universitet)
The Journal of Visualized Experiments. Jan 2013