The characteristics of stem cells in human degenerative intervertebral disc

The aim of this study is to identify which possessed the best stem-cell-like characteristics in 3 kinds of cell in human degenerative intervertebral disc: NPSCs (nucleus pulposus-derived stem cells), AFSCs (annulus fibrosus-derived stem cells), or CESCs (cartilage endplate-derived stem cells).

We separated the disc samples obtained from 15 surgically treated patients with disc degenerative diseases into nucleus pulposus, annulus fibrosus, and cartilage endplate. After cultivating, we used the cell counting kit-8 to analysis the cell activity of 3 kinds of disc tissue-derived stem cell separately; different stem cells were defined with multilineage (osteogenic, chondrogenic, and adipogenic) differentiation. We extracted the total RNA and detected the expression of different lineage differentiation-related genes with the real-time polymerase chain reaction (RT-PCR).

Cell morphology of NPSCs, AFSCs, and CESCs did not show significant difference. Cell proliferation capacity of NPSCs and AFSCs was stronger than that of CESCs. The differentiation outcomes showed that osteocyte-like cells were stained red by Alizarin red S, chondrocyte-like cells blue by toluidine blue, and adipocyte-like red by oil red O. The RT-PCR reflected that the expression of different lineage differentiation-related genes of AFSCs was stronger than NPSCs and CESCs.

In conclusion, we found that the cell morphology was not significantly different among NPSCs, AFSCs, and CESCs. Both differentiation and RT-PCR tests demonstrated that AFSCs had the best stem-cell-like characteristics in the human degenerative intervertebral disc.