Viewing hyaluronan: imaging contributes to imagining new roles for this amazing matrix polymer.

Hyaluronan (HA) is an ubiquitous extracellular matrix polymer that plays many roles in health and disease. The ability to view the spatial and temporal expression of HA in tissues and on/in cells has provided researchers with insights into the tremendously diverse biological processes in which HA is involved. Biochemical extraction, quantity, and size measurement of HA can tell part of the story, but these techniques are incomplete in placing HA at the scene of a biological event and determining which other molecules are likely to be cooperating. HA, however, is not immunogenic, so preparing antibodies for histochemistry is problematic. Fortunately, a probe for HA was devised based on the HA binding region of aggrecan, and today this probe is commercially available and very useful for histochemistry. This article discusses the conditions and considerations that the authors' lab and others have developed for optimal HA staining in many tissues and cell types.