Amyloid Scaffolds for Cartilage Tissue Regeneration
Maurice van Dalen is a PhD student in the department Nanobiophysics. (Co)Promotors are prof.dr. M.M.A.E. Claessens, prof.dr. H.B.J. Karperien and dr.ing J.N. Post from the faculty of Science & Technology.
Restoring cartilage tissue remains a clinical challenge, but could potentially treat many patients suffering from joint diseases, such as osteoarthritis. Therapies to regenerate cartilage often rely on scaffolds to provide (temporary) support until cartilage tissue is restored. In this Thesis, we investigate the potential use of scaffolds made of amyloid fibrils to improve cartilage tissue regeneration. Amyloid structures are functional biomaterials used by many species, that mimic several cartilage extracellular matrix features, and thus are a potential scaffold material for cartilage tissue regeneration. In addition, we look into methods to better determine if cartilage tissue has formed, rather than qualifying extracellular matrix components.
Therefore, we studied the effect of amyloid micronetworks (gels of amyloid with a diameter of tens of micrometres) of three different proteins on bovine chondrocytes. We monitored short and long term effects on cell viability, phenotype, and extracellular matrix deposition. Interestingly, we observed that all amyloid micronetworks supported cell viability, but only lysozyme amyloid micronetworks supported the cartilage cells’ phenotype, and promoted the deposition of extracellular matrix.
The viscoelastic properties of a scaffold are important to support chondrocytes with regenerating cartilage tissue. We focussed on amyloid gels of lysozyme and characterised their viscoelastic behaviour in simple buffers. Furthermore, we demonstrated that this viscoelastic behaviour measured is not necessarily representative of the viscoelastic behaviour in complex biological fluids; complex biological fluids are what the gels would experience in biomedical applications.
Proteoglycans are an essential part of the cartilage extracellular matrix. As the length of both the core and the sidechains is indicative of the stiffness of a construct containing proteoglycans, we investigated a protocol to isolate and image proteoglycans, followed by analysis of these lengths. We experienced technical issues during implementation of the protocol, and the protocol is not ready to be implemented despite optimisation attempts.
Lastly, we review our findings and also present some preliminary findings on the possible self-healing of amyloid gels, culture protocol improvements, and describe an experiment in which chondrocytes are cultured in suspension with lysozyme amyloid micronetworks. Over time they formed a single mass, and the cells remained viable for eleven months.Â
