A Nondestructive Raman Spectral Method for Temporal Tracking of Articular Cartilage Maturation

Because articular cartilage (AC) lacks inherent repair capacity, research has focused on translating tissue-engineered cartilage to the clinic. Toward this, rapid and nondestructive methods would be useful for determining in-process and release characteristics during the manufacture of tissue-engineered products. The current work aims to introduce a Raman-based methodology for nondestructive qualitative and quantitative characterization of tissue development using AC. First, Raman shifts associated with critical biochemical components of AC, with particular emphasis on DNA, glycosaminoglycans (long chains of sugar molecules and a key component of cartilage), total collagen, as well as pyridinoline (a marker of collagen crosslinking and maturation), were collated. Next, verification of the molecular spectroscopic biomarkers was conducted by temporally tracking tissue maturation/development of nascent and mature AC, establishing a temporal reference dataset. Finally, validation was performed by correlating the spectroscopic biomarkers with traditional photometric biochemical assays and mass spectrometry. The results presented here include a Maturity Index for quantification of tissue development/maturation. Strong correlations were found between nondestructive spectroscopic-based measurements and destructive (photometric and mass spectrometric) measurements with high linearity for both nondestructive Raman (R² > 0.96) and destructive biochemical (R² > 0.97) assays, respectively. Uses of the proposed rapid and nondestructive method include in-line quality assessment (in which the sample is not removed from the process stream) to monitor the manufacturing of tissue-engineered medical products. This study shows that Raman spectroscopy has the capacity of being a powerful tool for nondestructive quality control and assurance in traditional biomanufacturing workflows, and the approach taken here may also be utilized as a template and research tool for studies on the development of other native and engineered tissues.