Recapitulation of auricular cartilage microstructure.

Histological staining of native human auricular cartilage (A-C), disc constructs (D-L), and ear constructs (M-R) following 3 months in vivo. Picrosirius Red staining (A, D, G, J, M, P) displayed the formation of a perichondrium (PC) composed of collagen fibers at the perimeter of AuC and 1:1 disc and 1:1 ear constructs similar to native cartilage, while MSC discs were composed of fibrous collagen throughout. Safranin O staining with Fast Green counterstain (B, E, H, K, N, Q) displayed proteoglycan deposition and cell lacunae formation in AuC and 1:1 disc and 1:1 ear constructs similar to native cartilage, with no proteoglycan deposition in MSC discs. Verhoeff’s stain (C, F, I, L, O, R) displayed the formation of a maturing elastin fiber (EF) network in AuC and 1:1 discs similar to native cartilage, with less mature fibers appearing in 1:1 ear constructs. No elastin was observed in MSC discs. Scale bar = 100 μm for (A-O) and 4 mm for (P-R).