ABSTRACT
Objective Normal nucleus pulposus cells (nNPCs) can induce the differentiation of mesenchymal stem cells (MSCs).However, the inductive effect of degeneration nucleus pul-posus cells ( dNPCs ) on MSCs has not been determined .This study aimed to compare nNPCs with dNPCs in inducing MSCs into nucleus pulposuslike cells. Methods MSCs (cell line) were co-cultured with NPCs (cell line/isolated from patients with intervertebral disc degeneration) in 3D in vitro.The cells were divided into 5 groups:nNPCs control group, dNPCs control group, MSCs control group, nNPCs-MSCs group (MSCs induced by nNPCs), dNPCs-MSCs group (MSCs induced by dNPCs).After co-cultured for 7 days, the expression level of aggrecan (ACAN), type II collagen (COL-2), SOX-9, matrix metalloproteinase-1 (MMP-1) and MMP-3 in all the 5 groups'cellswere detected by RT-PCR and Western-blot. Results The RT-PCR results showed the expression of ACAN , COL-2 and SOX-9 in nNPCs-MSCs group was higher than that in dNPCs control group and dNPCs -MSCs group (all P<0.05).The expression of MMP-1 and MMP-3 in nNPCs-MSCs group and dNPCs-MSCs group was lower than that in dNPCs control group ( all P<0.01) , but there was no difference when compared with nNPCs control group and MSCs control group (all P>0.05).Western-blot analysis showed that the expression of ACAN , COL-2 and SOX-9 in nNPCs-MSCs group was higher than that in dNPCs control group and dNPCs-MSCs group (all P<0.05).The expression of MMP-1 and MMP-3 in nNPCs-MSCs group and dNPCs-MSCs group was lower than that in nNPCs control group and dNPCs control group ( all P<0.01) , but there was no difference compared with MSCs control group ( all P>0.05) . Conclusion Both nNPCs and dNPCs could induce the differentiation of MSCs into nucleus pulposus cells .After co-cultured with nNPCs, the expression level of ACAN, COL-2 and SOX-9 of MSCs was similar to that of nNPCs, which was superior to the induc-tion of MSCs by dNPCs under the same culture conditions .