Tissue Engineered Neocartilage using Polyglycolic Acid(PGA) and Chondrocyte

Choi, Min Hyuk; Whang, Kwi Whan; Park, Hung Jae

Abstract

Neomorphogenesis using tissue engineering technique by cell transplantation with biodegradable polymer has been introduced as a new method to achieve organ replacement or to create new tissues. Using this tissue engineering technique, neocartilage formation can be possible when isolated chondrocyte is combined with biocompatible and biodegradable polymer scaffolds. The purposes of this study are to investigate whether chondrocyte-polyglycolic acid(PGA) polymer can be designed to induce cartilage formation in a predetermined shape, to analyze the properties of neocartilage by histologic and immunohistochemical study. Chondrocytes were isolated from the articular cartilage of swine shoulder joint and seeded onto four PGA polymers(disc shape, diameter;1cm, thickness; 0.3 cm) at a concentration of 5 x 107 chondrocytes per cm3. Chondrocyte-PGA polymers were implanted into left side of subcutaneous pockets on the dorsa of 4 athymic mice. PGA polymers without chondrocyte were implanted into the right side of subcutaneous pockets of the same animals as a control study. The chondrocyte-PGA polymers were harvested 2, 4, 6 and 8 weeks after implantation and investigated grossly, histologically and immunohistochemically. Chondrocytes were also cultured in Ham's F-12 medium under 5% CO2 incubator at 37degrees C and analyzed by histologic and immunohistologic study. The analysis confirmed the following results: 1. In vitro study, it was confirmed by Hematoxylin-Eosin (H-E) stain and toluidine blue stain that histologic findings of cultured chondrocyte corresponded to normal chondrocyte. 2. After 4 weeks of implantation of chondrocyte-PGA polymer, specimens changed in gross finding to pearly white opalescence and firm on palpation and this findings were accentuated progressively. But PGA polymers without chondrocyte could not maintain its shape and were resolved gradually. 3. The appearance of normal immature cartilage was detected at 2 weeks of implantation of chondrocyte-PGA polymer in H-E stain and toluidine blue stain. Maturation process of cultured chondrocyte was observed by steps in the 4th, 6th and 8th week. 4. Using the immunohistochemistric study, the presences of Type II collagen and CD44 were confirmed in cultured chondrocytes. This finding meant that neocartilage could inherit the original properties of chondrocyte. 5. Nipple-shaped cartilage discs which could assure the mechanical and histologic properties of normal cartilage were successfully created. It seems to be possible to apply this method to other kinds of manufacture with various shaped-PGA polymer. This study showed not only new cartilage formation could be possible using chondrocyte and PGA polymer but also engineered tissue could be one of the modalities to treat the patients suffering from the shortage of tissue in the future. With further prudent researches, tissue engineering technique can be a distinguished armament in reconstruction of human body including cartilage.