Department of Microbiology and Immunology

Immunology and Cell Biology

The immune system: a dynamic network connecting organs and tissues to maintain the integrity of a living organism
  • Utilization of state-of-the-art imaging on living bone and other tissues
  • Elucidation of immune cell function and movement in the human body
  • Elucidation of cancer invasion and metastasis
  • Visualization and analyses of a respective single living cell at the molecular level
  • Next generation quantitative imaging to human applications
Professor Masaru Ishii
Immunology and Cell Biology
The lab started at the Institute for Cancer Research under the leadership of Keishi Matsumoto and later by Yukihiko Kitamura. It was then reorganized under the supervision of Toshio Hirano. The lab is currently headed by Masaru Ishii.

Development of state-of-the-art imaging systems to visualize living bone tissue

"Visualizing the interior of living bone tissue has been challenging owing to the fact that bone is extremely hard and opaque. In previous studies, researchers were only able to visualize bone specimens that were thinly dissected. However, when analyzed in this manner, the specimen is dead and cells are no longer moving. Thus, to observe living bone tissue, the lab has utilized special optical microscopy, two-photon excitation microscopy, and using it has successfully observed the medullary cavity. The lab is the first in the world to pioneer this approach, which will help to clarify biological phenomena in the bone marrow.

In vivo imaging of bone and bone marrow using 2-photon microscopy

Osteoclasts play an important role in bone remodeling by breaking down bone during inflammation or absorbing old bone under normal conditions. These cells are originally derived from macrophages in the blood, which migrate to the bone surface and become specialized to target bone. By visualizing live bone marrow, the lab was able to extensively analyze the mechanisms by which macrophages migrate to and destroy cells at the bone surface.

In particular, the lab found that sphingosine 1-phosphate (S1P), a physiologically active lipid, converts macrophages into osteoclasts in a tightly regulated manner. This finding has clarified why vitamin D has a positive effect on bone strength, as we found it regulates the S1P-mediated osteoclast conversion. In addition, we visualized osteoclasts catabolized bone, finding new information on both the number and state of osteoclasts for this function.

Various immune and blood cells are born and differentiate in the bone, which is also a hiding place for metastatic cancer cells. Analyzing the bone in a living state will contribute to not only immunology and hematology fields, but also various life science fields.

Sphingosine-1-phosphate mobilizes osteoclast precursors and regulates bone homeostasis

Recently, we have been using our imaging technology to observe other cell types, including liver, lung, etc. at the single cell level, to elucidate the whole picture of dynamic migratory network of immune cells.