Regeneration is a fascinating injury response that can be found widely across the animal kingdom. Previous studies have shown that macrophages are required for successful regeneration in a variety of different species and tissues. We wanted to investigate if macrophages have a role to play in lens regeneration in the Spanish newt. To do this, lens removal surgeries, or lentectomies, were performed on newts and the eyes were collected 30 days post lentectomy (DPL). To investigate the presence of macrophages in the newt eye before and after surgery, the collected eyes were stained for MPEG, a macrophage-expressed gene. Results show that there is increased macrophage presence after lentectomy. Knowing that macrophages are now present after injury, we tested to see if lens regeneration would be affected in macrophages were depleted. After lentectomies, the newt eyes were injected with either control PBS liposomes, or clodronate liposomes which target macrophages for cell death. At 30 DPL, the clodronate treated newts failed to form a lens, indicating that macrophages are necessary for successful lens regeneration. To better understand the role macrophages have on lens regeneration, we checked for EdU incorporation as a measure of cell proliferation. The eyes treated with the control liposomes showed many EdU cells, however, the clodronate treated eyes had significantly less EdU cells. This is a strong indication that macrophages aid in proliferation during regeneration. The opposite of regeneration in response to injury is the formation of a scar, also known as fibrosis. Fascinatingly, the macrophage depleted eyes were undergoing fibrosis. With this data supporting that macrophages play a key role in lens regeneration, future directions include comparing the molecular phenotype of newt and mouse macrophages. This information will help us better understand how to induce regeneration in mammals.
Author: Sophia Ratvasky
Advisor: Katia del Rio-Tsonis
Graduate Advisor: Georgios Tsissios
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