Fig. 4

Orthotopic implantation of human-derived cartilaginous aggregates. To challenge the stability of the hypertrophically differentiated cartilaginous organoids, we implanted these in critical size long bone defects. Following 8 weeks of implantation, no bone bridging was detected in the BMP4-, BIO-, T3- and BBT3-treated samples (A). Histological analysis using safranin-O further indicated that the implanted organoids remained largely stable (B) with no (C) to limited bone formation at the edges of the implant (D). Data represent observations collected from experiments (4 experiments per condition) using the CY2 cell line. The following abbreviations have been used to highlight the tissue composition in the sections: B: bone, C: cartilage, F: fibrous tissue, M: bone marrow and T: cartilage-bone turnover site (dotted rectangle)