Novel quality controls for nasal chondrocyte-derived tissue engineered cartilage

Cartilage defects are caused by injury, can be painful if left untreated, and may lead to degenerative joint diseases. Currently available treatments have not shown long-term predictable and durable results. Nasal chondrocytes have been investigated as an alternative to articular chondrocytes for engineering cartilage grafts due to their ability to produce high quality engineered tissues and reduced harm to patients’ knees. A phase II clinical trial is ongoing to investigate the efficacy of this treatment. A complete portrait of the tissue engineered therapy includes the characterization of the starting materials, i.e., nasal septal biopsy and the cells within. Potency assays must also be developed for tissue engineered therapies that are based on their hypothesized mode of action, i.e., the filling of cartilage defects with mature cartilaginous cells and matrix.
First, perichondrial cells were identified as the possibly contaminating cells obtained when harvesting nasal septal tissue. Increasing amounts of perichondrial cells were found to have a negative impact on tissue engineered cartilage.
For the development of identity and purity assays, gene expression panels as well as Raman spectroscopy were investigated in this thesis. The developed gene expression panels could differentiate between nasal chondrocytes and perichondrial cells. A novel application of Raman spectroscopy to distinguish the native nasal cartilage and perichondrium was proposed and could distinguish between the two tissue types.
For the development of potency assays, various methods were investigated. The expression of genes by expanded cells could be used to predict the maturity of the final engineered cartilage. Raman spectroscopy could be used to develop a nondestructive potency assay for clinically relevant tissue engineered cartilage. Finally, the automated grading of histological images was implemented using deep learning.
Prospectively, when the two- and five-year follow-up results from the patients become available, the hypothesized mode of action must be verified and the developed potency assays should be reevaluated to search for features of the tissue engineered products that correlate with good clinical outcome.