title: Tumorigenicity of poly-L-lactide (PLLA) plates compared with medical-grade polyethylene.
abstract: Poly-L-lactide (PLLA) plates, 20 x 10 x 1 mm in size, with flat surfaces, were implanted into 50 young male Wistar rats subcutaneously, and the incidence of tumors for 2 years under specific pathogen-free (SPF) conditions was evaluated. Tumors arose in 22 rats (at the implant sites in 20, and distant from the implantation site in 2). As a control, plates of medical-grade polyethylene of the same shape were implanted into 50 rats. Tumors appeared in 23 of these rats (21 at the sites of the plates, and 2 ectopically). In 30 rats given sham operations, no tumors appeared in the 2 year observation period. Histologically, all the tumors were mesenchymal malignant tumors resembling fibrosarcoma or malignant fibrous histocytoma (MFH) in humans. In 6 of the PLLA tumors and 3 of the PE tumors, bone formation was observed. There was no significant difference between the incidence of tumors caused by PLLA plates and that of tumors caused by medical-grade polyethylene plates. Macroscopically, PLLA plates retained their initial shape for 2 years. Scanning electron microscopy revealed small holes on the surfaces of the plates, and their molecular weight was reduced to 8% of the initial value.
authors.affiliation: Department of Artificial Organs, Kyoto University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: Y
authors.initials: Y
authors.lastname: Shimizu
authors.forename: N
authors.initials: N
authors.lastname: Okumura
authors.forename: T
authors.initials: T
authors.lastname: Matsui
authors.forename: S H
authors.initials: SH
authors.lastname: Hyon
authors.forename: T
authors.initials: T
authors.lastname: Shimamoto
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000633:toxicity*; D001835:Body Weight / Q000187:drug effects; D001859:Bone Neoplasms / Q000139:chemically induced / Q000473:pathology; D002273:Carcinogens / Q000633:toxicity*; D005354:Fibrosarcoma / Q000139:chemically induced / Q000473:pathology; D018219:Histiocytoma, Benign Fibrous / Q000139:chemically induced / Q000473:pathology; D008297:Male; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D012516:Osteosarcoma / Q000139:chemically induced / Q000473:pathology; D011091:Polyesters / Q000633:toxicity*; D011095:Polyethylenes / Q000633:toxicity*; D019736:Prostheses and Implants / Q000009:adverse effects*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001672:Biocompatible Materials; D002273:Carcinogens; D011091:Polyesters; D011095:Polyethylenes; C033616:poly(lactide)