Evaluation of platelet-rich plasma and hydrostatic pressure regarding cell differentiation in nucleus pulposus tissue...

Generation of a biological nucleus pulposus (NP) replacement by tissue engineering appears to be a promising approach for the therapy of early stages of intervertebral disc degeneration. Thereby, autologous mesenchymal stem cells (MSCs) represent an attractive cell source compared to cells of the NP that are already altered in their phenotype due to degenerative processes. This study compares the influence of 3D pellet culture and alginate beads, as well as that of different media compositions, by the addition of human platelet-rich plasma (PRP) or transforming growth factor (TGF-β1 ) in interaction with hydrostatic pressure on chondrogenic differentiation of human MSCs compared to NP cells. We found that gene expression of the chondrogenic markers aggrecan, collagen type 2 and collagen type 1 and Sox9 was considerably lower in cells cultivated with PRP compared to TGF-β1 . Immunohistology confirmed this result at protein level in pellet culture. Additionally, the pellet culture system was found to be more suitable than alginate beads. A positive influence of hydrostatic pressure could only be shown for individual donors. In summary, in comparison to TGF-β1 , human PRP did not induce adequate chondrogenic differentiation for both culture systems and cell types used. The mixture of growth factors in PRP promoted proliferation rather than chondrogenic differentiation. Based on these results, an application of PRP in human NP tissue-engineering approaches cannot be recommended.