Cellular evolution is one of the facts that keeps many doctors in business. When individual cells evolve into uncooperative units that replicate for their own purposes, instead of cooperating with the whole body, we call that cancer.
Very rarely, someone separates some of those mutated cells and gives them a safe place to grow and multiply, for a long time. About 50 years ago, a researcher did this with some cells from a cancer on Henrietta Lacks' cervix, and today, these cells are grown, around the world and have replicated a total mass, measured in tons.
They are a new species evolved from human cells, after mutations triggered by an infection by humanpappiloma virus. Their informal name is HeLa cells (from the first letters of Henrietta Lacks' name) but were eventually given the formal name, Helacyton gartleri. They have been used in almost all medical and lots of biological research, since their discovery.