gms | German Medical Science

Objective: Cell-based regenerative approaches have been suggested for the treatment of intervertebral disc (IVD) diseases. Alterations of immunogenic properties along IVD cell isolation and expansion and in 3D culture with various biomaterials, however, have been scarcely addressed. Therefore, our aim was to evaluate the immunogenic properties of mild and severely degenerated nucleus pulposus (NP) cells with regard to cell surface markers and co-cultures with autologous or allogenic peripheral blood mononuclear cells (PBMC) as well as changes of theses immunogenic properties after 3D culture.

Method: Ten patients with severe and mild grades of IVD degeneration were included. NP cells were isolated, expanded and cultured in 3D fibrin/PLGA transplants. NP cells were evaluated for induction of immune responses in co-culture with PBMC from the same donor or from an allogenic donor, using a 5,6-carboxyfluorescein diacetate N-succinimidyl ester-based proliferation assay. Surface marker detection and evaluation of cytokines was performed by Cytometric Bead Array and FACS analysis.

Results: All cells expressed HLA-ABC and CD95 (Fas), but lacked expression of HLA-DR and CD24. NP cells after monolayer culture did not provoke a significant proliferation of T cells, NK cells or B cells from either the same donor or from allogenic PBMC. NP cells in a 3D matrix, however, provoked the immune cell proliferation to a greater extent than in monolayer culture. 3D specimens containing NP cells from patients with severe degeneration tended to provoke a larger response, especially for CD3+CD8+ and CD3+CD4+ T cells, than those with mild degeneration. In general, the cytokine release was low, especially for the inflammatory cytokines TNF-alpha and IFN-gamma.

Conclusions: NP cells in monolayer, regardless of their grade of degeneration, did not provoke a significant proliferation response in T cells, NK cells or B cells. In conjunction with low inflammatory cytokine expression, a low immunogenicity can be assumed, facilitating possible therapeutic approaches. In 3D culture, however, we found higher immune cell proliferation levels. This emphasizes the importance of considering specific immunological alterations when including biomaterials into a therapeutic concept. The overall expression of Fas receptor on cultured NP cells could have disadvantageous implications on their potential therapeutic applications because of cytotoxic T-cell activity acting by Fas ligand-induced apoptosis.