Electronic Thesis and Dissertation Repository

Thesis Format



Master of Engineering Science


Biomedical Engineering

Collaborative Specialization

Musculoskeletal Health Research


Flynn, Lauren E.

2nd Supervisor

Séguin, Cheryle A.

Joint Supervisor


Biomaterials-based therapies targeting the nucleus pulposus (NP) have the potential to promote regeneration and restore mechanical function to the intervertebral disc. This study developed composite hydrogels incorporating decellularized NP (DNP) and assessed its effects on viability, retention and differentiation of U-CH1 cells, an NP progenitor-like cell line. A minimal protocol was developed to decellularize bovine NP that reduced nuclear content while preserving key extracellular matrix components predicted to be favourable for bioactivity. The resulting DNP demonstrated cell-instructive effects, supporting U-CH1 viability and retention within the hydrogels, and promoted the differentiation of the progenitor-like cells towards an NP-like phenotype. These studies established a 3D platform that mimics the native NP microenvironment and holds promise for applications in cell culture and delivery. Further in vitro studies using this system will provide valuable insight into the effects of tissue-specific extracellular matrix on NP progenitor cell fate.

Summary for Lay Audience

Back pain is the most common cause of disability worldwide. While the cause of low back pain is complex, it is often linked to intervertebral disc (IVD) degeneration. Although IVD degeneration is multifactorial, it is believed to initiate in the central gel-like region of the disc, known as the nucleus pulposus (NP). Current treatments focus on pain management by medication, physiotherapy and/or exercise therapy; however, there are no disease-modifying treatments available for IVD degeneration. Surgical interventions can alter spine biomechanics, leading to further degeneration of adjacent discs. These limitations have inspired biomaterials-based therapies to regenerate the NP and restore mechanical function to the spine. This study developed injectable biomaterial scaffolds using extracellular matrix (ECM) from bovine NP tissues as a cell-instructive component. The ECM is a tissue-specific complex network of proteins and polysaccharides that provides structure and directs cell function. Existing techniques to isolate the NP ECM use harsh chemicals and strong detergents to remove donor cells, with the goal of creating off-the-shelf scaffolds that could be applied in humans without causing a negative immunological response. This thesis developed a new minimalistic protocol for isolating ECM from bovine NP tissues with the goal of better preserving the structure and composition of the native ECM to enhance bioactivity. Once the protocol was developed and validated, particles of the isolated NP ECM were incorporated into an injectable hydrogel, a gel material that can retain a large amount of water to support encapsulated cell populations and resembles the structure of the NP ECM. As a first step towards testing the regenerative potential of this material, the behaviour of human NP precursor-like cells within the hydrogels were assessed. The results indicated that the NP ECM enhanced the survival of the precursor cells within the gels and promoted a more mature NP-like cell phenotype. These studies represent a key first step in developing a new injectable biomaterial with potential clinical application for the repair or regeneration of the NP and to restore mechanical function to the IVD.