48 Towards a reproducible intervertebral disc model – a bioprintable nucleus pulposus-like material
Disc degeneration is a major source of pain and disability in patients worldwide, and a significant financial burden on healthcare providers. Attempts at addressing it through tissue engineering and regenerative medicine research are limited by the lack of a suitable model recapitulating the intrinsic features of the intervertebral disc (IVD). The IVD is a complex heterogeneously composed organ, subjected to a challenging mechanical environment. Presently available models of the IVD are inadequate, differing in composition, organization, and mechanical properties. Despite previous efforts, a standardized full IVD 3D model recreating the native tissue and providing the necessary biochemical cues and mechanical performance has not been reported yet.
With the goal of mimicking the gel-like nucleus pulposus in the core of the intervertebral disc, a tyramine derivative of hyaluronic acid was combined with unmodified type I collagen, preparing a bioink with double-crosslinking capabilities. These were utilized in a stepwise manner to ensure adequate printability following an initial enzymatic crosslinking, and to further strengthen the material via light crosslinking after printing. Various compositions of the bioink were first evaluated rheologically, determining their printability, and comparing their performance to that of native tissue. As a proof of concept, simple lattice-based structures were then printed.
The presented bioink system offers a versatile approach to 3D printing due to its double-crosslinking mechanism. Our work demonstrates that with the use of modified matrix components, this mechanism is a viable method of recreating nucleus pulposus-like structures, bringing us a step further towards a 3D printed IVD model.