Abstract
Background
Current clinical treatment for spinal instability requires invasive spinal fusion with cages and screw instrumentation. We previously reported a novel injectable hydrogel (Bgel), which supports the delivery and differentiation of mesenchymal stem cells (MSCs) to bone forming cells and supports bone formation in vivo. Here, we investigated whether this system could be utilised to induce bone formation within intervertebral disc tissue as a potential injectable spinal fusion approach.
Methodology
Bovine and Human Nucleus pulpous tissue explants were injected with Bgel with and without MSCs. Tissue samples were cultured under hypoxia (5%) in standard culture media for 4 weeks. Cell viability, histological assessment of matrix deposition, calcium formation, and cell phenotype analysis using immunohistochemistry for NP matrix and bone markers.
Results
Following injection of B-gel into tissue explants following culture for 4 weeks, cells were visualized within the regions of the B-gel. Demonstrating that native cells were able to migrate into regions of B-gel. Increased collagen deposition was seen in tissue explants injected with Bgel, with increased collagen type I and X but decreased collagen type II staining in explants injected with Bgel. Tissue explants, in the absence of Bgel, showed limited calcium deposition, which was increased in B-gel injected explants. Furthermore, disc cells increased expression of bone markers (alkaline phosphatase & osteocalcin), but decreased NP matrix (Aggrecan and Collagen type II) following Bgel injection.
Conclusion
This system could have potential to support spinal fusion via direct injection into the disc.
Conflict of interest: C Le Maitre & C Sammon are inventors on the hydrogel discussed.
Funding: This work was funded by GrowMed Tech Proof of Concept funding.
