Stimulation of intervertebral disc cells in alginate bead culture with bone morphogenetic protein 2 and/or L51P

Introduction: In clinics, Bone Morphogenetic Protein 2 (BMP2) was applied to support spinal fusion. Further BMP2 was tested in IVD models and showed potential for IVD regeneration. The aim of this study is the investigation of BMP2 and L51P on different cell types of the human IVD in 3D alginate beads, particularly their plasticity to undergo bone formation. Methods: Human nucleus pulposus (NPC), annulus fibrosus (AFC) and cartilaginous endplate cells (CEPC) were each encapsulated in 1.2% alginate at a density of 4 Mio/mL. NPC, AFC, and CEPC beads were then cultured in α-MEM or osteogenic medium (OM) supplemented with 10% FBS and 100 ng/mL BMP2 or L51P for seven days. After four days, medium supplemented with cytokines was refreshed. Beads were then snap frozen with liquid nitrogen and analyzed by qPCR and Alcian Blue staining. Results: Aggrecan (ACAN) expression was the highest up-regulated in IVD cells stimulated with OM and 100 ng/ml BMP2 and L51P compared to negative control (basal medium) in NPC, AFC and CEPC (mean ± SEM NP: 18.95 ± 15.65). The same was true for Collagen type 2 (COL2) expression (NP: 72.47 ± 62.95). COL1 remained unaffected (N=2). Conclusion: Recent studies confirmed the anabolic effect of BMP2 on IVD. Also, we showed the trend of an increase in ACAN and COL2 gene expression in stimulated cells. Like in previous studies collagen type 1 (COL1) expression in stimulated IVD cells was unaffected. Interestingly showed the co-treatment of BMP2 and L51P a cumulative effect towards an increased ECM production