NTG-102: A Refined Molecular Therapeutic to Treat Degenerative Disc Disease

Background Degenerative Disc Disease (DDD) is characterized by the death of IVD cells, degradation of healthy extra-cellular matrix proteins, the overexpression of pro-inflammatory cytokines and matrix degradation enzymes as well as structural compromise of the IVD. A successful biological therapy needs to induce repair and promote cell viability as well as confer anti-inflammatory / anti-catabolic effects upon the degenerative IVD. Materials and Methods Bovine IVD-nucleus pulposus (NP) / annulus fibrosus (AF) cells encapsulated in alginate bead hydrogels (3D-cell culture) cultured under hypoxic conditions were used as in vitro models to test the efficacy of NTG-102 (i.e., rhTGF-β1 mixed in excipient solution) for its therapeutic potential. In addition, we used degenerative, painful IVD tissues derived from patients undergoing discectomy or fusion surgery to compare the levels of Collagen type 2A1 in samples that were immunopositive or negative to TGF-β1 protein. Results Treatment with NTG-102 in the presence of IL-1β increased the expression of healthy ECM proteins aggrecan and collagen type 2 (ACAN / Col2A1), reduced the gene expression of the inflammation and pain marker (Cox-2) and the matrix degrading enzyme (MMP-13) in bovine IVD-NP/AF 3D-cell culture models in vitro. Moreover, treatment with rhTGF-β1 preferentially activated and sustained phsopho-Smad-2/3 signaling whereas phosphorylation of the Smad-1/5 pathway was undetectable in 3D-cell culture models of bovine IVD-NPs. Further, immunohistochemical analysis revealed significantly higher Col2A1 protein expression in TGF-β1 immunopositive patient derived degenerative IVD tissues than in TGF-β1 negative samples. Conclusions Notably, treatment with NTG-102, containing rhTGF-β1 as an important key ingredient, demonstrated higher in vitro efficacy in both IVD-NP / AF models of DDD by inducing anabolic repair and suppressing inflammation / catabolic changes. The loss of TGF-β1 protein expression in a majority of the patient-derived human tissue samples was associated with a loss of collagen type 2 ECM protein and the onset of a catabolic microenvironment in IVD.