How this works is through the stem cell's production of growth factors, proteins, peptides and collagens which have the ability to renew damaged cells when injected into a damaged area. The material produced by the stem cells serves to communicate with the other cells and stimulate their growth when they need to begin healing or producing new cells to replace the ones that are too far gone. The damaged cells within the tendon in the shoulder get repaired, restored or replaced, leaving a tendon that no longer hurts, and allows for full function again.