The concept is that they are naturally-derived materials, often from the patient's own body, and contain cells and chemicals that promote self-healing.
Platelet-rich plasma (PRP)
To derive this material, the patient's own blood is centrifuged and the layer separated out which is rich in platelets. This is injected into the part of the body that is damaged. These contain healing substances, and trigger the body to heal itself.
Bone marrow-derived stem cells
They include autologous stem cells, allograft non stem cell therapies like amniotic fluid or umbilical cord blood