Stem Cell Therapy involves using stem cells to treat medical conditions. Stem cells are cells that have not differentiated into specific cell types. Scientists can manipulate these undifferentiated cells into the cell type the patient needs and then implant these healthy new cells into the patient; the new cells can help improve the condition of the patient. The stem cells can come from the patient, from the lab, or from a donor. In the case of joint repair, doctors can take stem cells from the patient's own bone marrow or fat tissue, or stem cells from an amniotic sac, and inject this into the joint in question to help improve healing or reduce inflammation.