Healing of the eye's retina after injury is aided by immune cells that dampen local inflammation and boost the retina's capacity for repair.

Michal Schwartz at the Weizmann Institute of Science in Rehovot, Israel, and her team monitored the influx of cells called macrophages from the blood into the damaged retinas of mice. They found that the immune cells flooded the retinas, with most homing in on the area of damage — the layer containing the retinal ganglion cells (RGCs). Boosting macrophage levels enhanced the survival of RGCs and triggered proliferation of retinal progenitor cells. The macrophages also altered the levels of immune regulators to decrease inflammation in the damaged retina.

The authors did not find any signs of newly generated mature retinal neurons. They therefore suggest that the progenitor cells provide a protective environment, for example by modulating the immune response, rather than replacing damaged cells.

J. Exp. Med. doi:10.1084/jem.20101202 (2011)