Sensing tissue engineered cartilage quality with Raman spectroscopy and statistical learning for the development of advanced characterization assays

Nasal chondrocyte-derived engineered cartilage has been demonstrated to be safe and feasible for the treatment of focal cartilage lesions with promising preliminary evidences of efficacy. To ensure the quality of the products and processes, and to meet regulatory requirements, quality controls for identity, purity, and potency need to be developed. We investigated the use of Raman spectroscopy, a nondestructive analytical method that measures the chemical composition of samples, and statistical learning methods for the development of quality controls to quantitatively characterize the starting biopsy and final grafts. We provide a proof-of-concept to show how Raman spectroscopy can be used to identify the types of tissues found in a nasal septal biopsy, i.e., hyaline cartilage and perichondrium, for a novel tissue identity assay. The tissues could be classified with a sensitivity of 89% and specificity of 77%. We also show how clinically relevant and mature nasal chondrocyte-derived engineered cartilage can be assessed with Raman spectroscopy for the development of potency assays. The maturity of engineered grafts, based on the quantified ratio of glycosaminoglycans to DNA and histological score, could be accurately assessed (R2 = 0.78 and 0.89, respectively, between predicted and measured values). Our results demonstrate the potential of Raman spectroscopy for the development of characterization assays for regenerative therapies that could be integrated into a good manufacturing practice-compliant process.