Immune system found to control eye tissue renewal in zebrafish

The findings are significant, insofar as they may one day advance efforts to combat damage stming from degenerative eye disease in humans, as evolution has likely conserved with mechanism of regenerative potential in other animals.According to study author Associate Professor Jeffery Mumm, the secret lies in an inducible st cell called the Müller glia (MG), which can be found in the eyes of both humans and zebrafish.{{quote-A:R-W:450-I:2-Q: Humans still have the genetic machinery needed to regenerate retinal tissue, if we can activate and control it. -WHO:Jeffery Mumm}}“At the cellular level, zebrafish and human eyes are rarkably similar,” Mumm said, while explaining that his team had discovered that microglia, a cell type found in most vertebrate innate immune systs, affected MG’s regenerative response and could be harnessed to accelerate the growth of new tissues in the retina.“Humans have an evolutionary block on our ability to regenerate certain tissues. But humans still have the genetic machinery needed to regenerate retinal tissue, if we can activate and control it,” Mumm explained.The team experimented with a model of retinitis pigmentosa (RP) in zebrafish by incorporating a gene for a specialised enzyme into the rod cells of the fish retina. The enzyme, which has a unique ability to convert the chical metronidazole into a toxin, allowed researchers to selectively kill the cells expressing it.Once the photoreceptor loss was initiated, the team monitored the immune syst responses by tracking three types of immune cells – microglia, neutrophils and peripheral macrophages – that were all marked with distinctive fluorescent dyes. Cellular activity was studied using 3D time-lapse microscopic imaging.The scientists found that microglia were the only cells able to both respond to the injury and reach the injured cells. Additionally, they found that when microglia were also lost, MG showed almost no regenerative activity after three days of recovery, compared with approximately 75% regeneration in the control population.The researchers hope that by harnessing the ability to improve regeneration in zebrafish, they will be better able to understand how to achieve the same results in human eyes. Part of the future research will focus on improving imaging techniques to build a more comprehensive understanding of how immune cells impact the regeneration process.More information:–  Full study