FIGURE 3.

Cell sources proposed for NP regeneration: Studies investigating potential cellular therapy to regenerate the NP expanding over 26 years (from January 1994 to December 2020) were classified according to cell source proposed: the number (A), percentage (B) of cell type and the percentage of cell type relative to the year (C) which used the following cell types: Adipose derived mesenchymal stem cells (ADMSC), annulus fibrosus (AF) cells, bone marrow derived mesenchymal stem cells (BMSC), chondrocytes (subgroups include: endplate chondrocytes, hyaline chondrocytes, articular chondrocytes, nasal chondrocytes, and auricular chondrocytes), fibroblast cells, gynecological cells (subgroups include: menstrual blood derived stem cells, and human amniotic cells), hematopoietic stem cells, human embryonic stem cells (hESC), human umbilical cord stem cells (hUSC; including placenta derived mesenchymal stem cells), induced pluripotent stem cells (iPSC), muscle derived stem cells, notochordal cells (NC), nucleus pulposus cells (NPC), olfactory stem cells, and synovial derived mesenchymal stem cells. (B) From the literature extracted: 40% used BMSC; 26% used NPC; 12% ADMSC; 6% used chondrocytes; 3% used iPSC; 3% used hUSC; 3% used NC cells; 2% used AF cells; 2% used fibroblasts; <1% used hESC; <1% used synovial MSC; <1% used gynecological cells; <1% used olfactory SC; <1% used muscle SC; <1% hematopoietic SC