Implantation of Cell-Seeded Biodegradable Polymers for Tissue Reconstruction
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IMPLANTATION OF CELL-SEEDED BIODEGRADABLE POLYMERS FOR TISSUE RECONSTRUCTION
KAZUSHI ITO, TOSHIYA FUJISATO, AND YOSHITO IKADA Research Center for Biomedical Engineering, Kyoto University, Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606, Japan INTRODUCTION The aim of this work is to use biodegradable polymers as a scaffold for self-reconstruction of defective tissue which has the capacity to regenerate; for instance, cartilage, blood vessel, bone, peripheral nervous system, and liver. After seeding parenchymal cells of the target tissue on the scaffold, the cellpolymer composite will be implanted as the core tissue for reconstruction. There is another approach for this purpose, that is, the use of hybrid-type artificial organs, but they have several problems such as poor viability and low capacity. In addition, it is difficult to culture cells on a large enough scale to maintain biofunctionality. However, these problems may be solved if tissue is self-reconstructed in body on a scaffold seeded with the cells originated from the objective tissue [1]. In this study, we investigated the possibility of using the poly(L-lactic acid) (PLLA) and poly(glycolic acid) (PGA) non-woven fabrics as the biodegradable scaffold with short-term implantation. Rabbit liver and rat cartilage were selected as the target tissues, because it is easy to isolate the cells and easy to autograft, especially when rabbit liver is used. EXPERIMENTAL
PLLA and PGA non-woven fabrics whose fiber diameter is 5 gim were offered by Gunze Company. Two sheets of fabrics were cut to have round shape of 1.5 cm diameter, and then overlapped each other and sewn around by surgical suture. As a control, non-biodegradable polyethylene telephthalate (PET) nonwoven fabrics were used. All the fabrics were sterilized by 70 % ethanol overnight, and then washed by phosphate buffered saline. A piece of rabbit liver was surgically removed without sacrificing the animal, and the tissue was perfused for 15 min with an oxygenated solution of 0.05% collagenase to remove the hepatocytes from the liver bed [3]. The costal cartilage chondrocytes were isolated from rats by 0.25% trypsin and 0.05% collagenase treatments for one hr [4]. All the procedures were done with clean technique. For the in vitro study, the cells were seeded on various polymer surfaces in 24 multi-well dishes at a density of 5.7x10 4 cells/cm 2 . After predetermined periods of time, the cell appearance was observed with a light microscope. Cells
Mat. Res. Soc. Symp. Proc. Vol. 252. 91992 Materials Research Society
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were counted by quantifying the activity of lactate dehydrogenase in the cells after complete digestion using test kits for clinical use. In addition, the concentrations of serum albumin and collagen (type II) in the supernatant of culture dishes were measured using an ELISA technique. Williams' E culture medium with insulin and epidermal cell growth factor was used for rabbit hepatocytes, and Eagle MEM for rat chondrocytes [6]. The cell suspension of lx106 cells was injected via needle into
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