Tissue Engineered Growth of New Cartilage in the Shape of a Human Ear Using Synthetic Polymers Seeded with Chondrocytes
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TISSUE ENGINEERED GROWTH OF NEW CARTILAGE IN THE SHAPE OF A HUMAN EAR USING SYNTHETIC POLYMERS SEEDED WITH CHONDROCYTES CHARLES A.VACANTI 1, LINDA G. CIMA2 , DIANNE RATKOWSKI 3 ,JOSEPH UPTON 4 , and JOSEPH P. VACANTI 4 1 Mass. General Hospital, Department of Anaesthesia, Boston, MA 02114 2 Massachusetts Institute of Technology, Chemical Engineering Dept., Cambridge, MA 02139 3 Boston University, Department of Otolaryngology, Boston, MA 02114 4 Children's Hospital, Department of Surgery, Boston, MA, 02115. Abstract This report concerns the tissue-engineered growth of new cartilage in the shape of a human ear. Using synthetic biodegradable polyesters, a porous, three dimensional device in the shape of a human ear was fabricated. The polymer matrices were seeded with living chondrocytes isolated from a freshly sacrificed calf shoulder and implanted subcutaneously on the dorsum of athymic rats. This resulted in the formation of new cartilage in the shape of a human ear of approximately the same dimensions as the original implants. Histological analysis revealed the presence of mature cartilage in all specimens. Introduction Prosthetic cartilage replacements are widely used in plastic surgery, and they generally serve as an adequate, but not optimal, replacement for natural tissue. The cartilage structure of the human outer ear offers a particular example of the shortcomings of prosthetic cartilage replacements. Two major alternatives are currently available to the plastic surgeon carrying out reconstruction of the human outer ear: silicone rubber prostheses and sculpted autologous bone. As with any foreign body, silicone prostheses are prone to infection at the the materialtissue interface. These prostheses are particularly vulnerable because of their proximity to the surface of the skin, and a wound in the skin often leads to infection which nessecitates removal of the device. The second alternative, sculpting autologous rib bone, is not optimal because the resulting replacement lacks the resiliency and gross morphology of the native structure. An ideal replacement would be formed of natural cartilage. The approach we are taking toward this goal is to transplant chondrocytes using a synthetic biodegradable polymer template formed in the desired shape. Following transplantation, the polymer will resorb and the isolated chondrocytes will form cartilage under the right conditions12 . Previous studies which demonstrated the formation of hyaline cartilage from chondrocytes transplanted with biodegradable polymer matrices were carried out with matrices of an amorphous shape. Application of the technique to plastic surgery requires that the polymer scaffold must be designed to hold a specific shape, and have some intrinsic flexability and strength in order that the cartilage created would have the appropriate morphologic appearance and texture. In order to provide suitable conditions for growth of cartilage in vivo, the device must also be porous enough to allow for homogeneous seeding of a sufficient concentration of chondr
