In recent years there has been an increase in the need for tissue replacement in the head and neck region. The disadvantages of classical reconstructive procedures are donor site morbidity for autologous transplants and the immunogenity of allogenous transplants. Tissue engineering is a promising method for the generation of autologous cartilagenous transplants for plastic and reconstructive surgery for closure of large defects by the use of minimal amounts of material for reconstruction. For this purpose harvested material must be cultivated in suitable culture/carrier systems. One obstacle is the loss of phenotype and function once the cells are detached from their environment (dedifferentiation). Adult mesenchymal stem cells are a valuable cell source for tissue engineering. The underlying strategy of using stem cells is the replacement of functionally compromised cells either by in vitro expanded stem cells or activation of stem cells in the tissue. However, there are still problems regarding valuable markers for cellular differentiation and the controlled differentiation towards a specific phenotype.