English: For isolation of chondrocytes, plastic surgeons harvest autologous septal cartilage (6 mm diameter) under local anesthesia. On the same day, venous blood is collected to prepare autologous serum. The cartilage biopsy specimen and the blood sample are transported to the Good Manufacturing Practice (GMP) facility. Here the cartilage cells (nasal chondrocytes) are isolated by enzymatic digestion of the cartilage biopsy, expanded and cultured onto collagen membrane to engineer cartilage grafts (30 x 40 x 2 mm). Throughout the graft manufacturing phase (total time: 4 weeks) regular sterility controls are done. Quality control tests for release of the grafts included absence of any contamination of cultured media and presence of at least 70% viable cells throughout the deposited extracellular matrix. Based on these criteria, the graft is released and transported to the operating room. Here the graft is trimmed to the individual defect size and then implanted into the femoral defects via miniarthrotomy.