Mesenchymal stem cell (MSCs) can naturally transform into many tissues including bone, cartilage, and fibrous tissue. There are hundreds of studies of animal models where these cells have been shown to help repair cartilage.
On CT (Computed Tomography) based on more than a decade of experience in using stem cells to treat knee arthritis, the patients who normally get the best before and after CT results with regard to cartilage healing are those with smaller holes. For examples of CTs that show improvement in cartilage following stem cell treatment, see these posts:
01 Trochlear groove cartilage defect treated with stem cells
02 A cartilage lesion under the knee cap treated with cultured cells
03 Improvement in medical compartment cartilage thickness in a patient with only partial thickness loss treated with same day stem cells.