Evaluation of Engineered Cartilage Composition and Function Using Raman Spectroscopy

A Raman spectroscopy-based platform has tremendous potential to non-destructively monitor the evolving composition of tissue-engineered cartilage (TEC) responsible for its mechanical properties from in vitro cultivation to post-implantation in vivo function. Raman spectroscopy, an inelastic light scattering technique, reflects the biochemical building blocks (amides, sulfates, and hydroxyls) comprising a tissue. Here, an arthroscopy-compatible probe acquires Raman spectra, and a multivariate linear decomposition routine extracts the regression coefficient biomarkers that reflect the contribution of extracellular matrix (ECM) constituents (sulfated glycosaminoglycans [sGAG], collagen, water) and the scaffold biomaterial to the tissue spectra. Repeated Raman acquisitions during cultivation do not alter growth of chondrocyte-seeded-agarose constructs. The Raman-derived ECM biomarkers portray the composition of the evolving neocartilage developed on agarose, hyaluronan, collagen, and polyethylene-glycol scaffolds, accounting for 90%, 78%, and 87% of content variation in sGAG, collagen, and water, and 94% of the variation in stiffness. The ECM biomarkers reveal variability in sGAG and collagen content for constructs infused with donor chondrocytes from a 58-year-old/female, a 36-year-old/male, and a 53-year-old/male, accounting for 81% and 87% of the variation in stiffness and sGAG content. This Raman platform offers a transformative approach enabling optimization of construct fabrication, improving preclinical evaluation, and advancing cartilage regenerative therapies.