Fresh insights into how zebrafish repair their damaged nerve connections could aid the development of therapies for people with spinal cord injuries. Scientists have found the immune system plays a key role in helping zebrafish nerve cells to regenerate after injury. The findings offer clues for developing treatments that could one day help people to regain movement after spinal cord injury. Large immune cells called macrophages are vital for the fish to repair damaged connections, the study found. These cells usually help the body to fight off infections but they also play a key role in wound healing.