Stem cells are produced in a laboratory. They are isolated from the blood and cultivated in order to obtain a very high concentration of pure stem cells. They can be either differentiated or undifferentiated. The undifferentiated cells have the ability to adapt to any type of cell, which can sometimes cause problems. This is why we use differentiated stem cells. These adapt to a specific tissue (tendon stem cells for tendon injuries, cartilage stem cells for cartilage injuries, ...), so that healing is much faster.