Tissue engineering: the current status of this futuristic modality in head neck reconstruction

To define tissue engineering and describe the components that are involved in engineering tissue. To provide examples of the most recent developments in tissue engineering as they apply to the otolaryngologist. To provide a general overview of selected exciting advances outside the field of general otolaryngology but of general interest to the reconstructive community.

Tissue engineering is a rapidly evolving field that can be defined as the regeneration of new tissues through the use of biologic mediators and matricis. The three components required are scaffolds, signaling molecules, and cells. A significant amount of work has been done to generate bone, cartilage, cornea, and vascular grafts. Tissue engineered bone is the only tissue type that has been evaluated in Phase III clinical trials and is in routine clinical use. Engineered bone from BMP-2 and BMP-7 is used in orthopedics for lumbar fusions and long bone nonunions. Clinical application of bone tissue engineering in the head and neck is limited to case reports. There has been success in tissue engineering with cartilage for the nose and ear in immune incompetent animal models but there has been difficulty with generating scaffolds that do not incite an immune reaction in an immune competent model. The most advanced organ engineered is a bladder that has been successful in a canine model.

Tissue engineering holds the promise of "off the shelf" parts for reconstruction of tissues and organs. The widest clinical application is with bone in orthopedics. Applications in the head and neck are limited, at present, due to the immunogenicity of the scaffolds and the challenging wounds encountered in both cancer and cosmetic patients.