Fig. 2

Engineering of stratified, mechanically functional human cartilage. a Human mesenchymal stem cells are induced to fuse into cell bodies which are then placed on the cartilage side of a mold in the exact shape of a condyle, an anatomically shaped bone scaffold is placed on the other side, and the two pieces are press-fit. After 5 weeks of in-vitro cultivation, an anatomical layer of articular cartilage forms at the interface with the underlying bone. b The resulting cartilage is physiologically thick and stratified, expressing all key markers, and integrated with the underlying bone. c The fusing mesenchymal stem cell bodies were also tested for their ability to repair small cartilage defects. Structural integration is shown by alcian blue and antibody stains for glycosaminoglycan and collagen type II. The newly formed tissue is shown on the left, the adjacent native cartilage on the right. Selected images are reproduced with permission from [73]. H & E hematoxylin and eosin