Label-free microscopy for studying individual immune cells

Fluorescence methods have allowed scientists to label and follow single living cells with optical microscopy, revealing much about how cells work. However, the fluorophores used in these methods can be large and sometimes require invasive methods to get them into the cells, thus we don’t know how they really affect cell behavior.

Ideally, scientists would study cell behavior under conditions as close to natural as possible. Researchers at the University of Rochester have come closer to this ideal by creating an integrated Raman spectroscopy and angular-scattering microscopy (IRAM) system and using it to image unlabeled human live immune cells. The work is detailed in the latest issue of Applied Optics.

Raman spectroscopy provides chemical information about the sample, while angular-scatting microscopy acquires structural information. Together this is enough information to distinguish individual cells of different types.

The researchers were able to use the microscopy system to identify single granulocytes and peripheral blood monocytes -- two components of the human immune system. They next want to use the system to gather continuous data, which could allow the study of things such as how individual cells respond to various stimuli, to observe early changes in cells involved in an immune response or cancer, and to follow how cells change over time.

Applied Optics paper:
Zachary J. Smith and Andrew J. Berger, "Validation of an integrated Raman- and angular-scattering microscopy system on heterogeneous bead mixtures and single human immune cells," Appl. Opt. 48, D109-D120 (2009)