Histological study of articular cartilage in experimental rat knee arthritis induced by intracapsular injection of cationic polyethyleneimine.
Degeneration of proteoglycans and abnormalities in their metabolism have been assumed to be critical at an early stage of osteoarthritis. To clarify a trigger mechanism of osteoarthritis, anionic sites of knee articular cartilage were blocked by intracapsular injection of cationic polyethyleneimine of 2000 or 70,000 molecular weight (MW) into rat knee joints. Experimental or normal rats were examined by gross observation, roentgenography, cytokine interleukin-1beta (IL-1beta) assay, and light or electron microscopy. In both groups with the polyethyleneimine injection, the rats showed temporarily limping and swelling of their knee joints. By light or electron microscopic studies, knee articular cartilage was found to be degenerated at an early stage, but IL-1beta was within normal levels. At 2, 4, or 6 months, the deformity of the knee joints was obvious by roentgenography. Degeneration and hypofunction of proteoglycans might be related to the ultrastructural changes of articular cartilage at an early stage, though the inflammatory cytokine was not involved. At later stages the pathophysiology of the knee joints advanced chronically to typical osteoarthritis, which was more radically induced by the large molecular polyethyleneimine (70,000 MW). The functional impairment of anionic sites is a key point for elucidating the mechanism of osteoarthritic development in this animal model.
Sakano
Y
Y
Department of Orthopaedic Surgery, Yamanashi Medical University, Tamaho, Yamanashi 409-3898, Japan.
Terada
N
N
Ueda
H
H
Fujii
Y
Y
Hamada
Y
Y
Akamatsu
N
N
Ohno
S
S
D000818:Animals; D002358:Cartilage, Articular / Q000473:pathology* / Q000648:ultrastructure; D003094:Collagen / Q000032:analysis; D007375:Interleukin-1 / Q000032:analysis; D007719:Knee Joint / Q000473:pathology* / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D010003:Osteoarthritis / Q000139:chemically induced / Q000000981:diagnostic imaging / Q000473:pathology*; D011094:Polyethyleneimine / Q000633:toxicity*; D011509:Proteoglycans / Q000378:metabolism; D011859:Radiography; D051381:Rats; D011916:Rats, Inbred F344
D007375:Interleukin-1; D011509:Proteoglycans; D011094:Polyethyleneimine; D003094:Collagen