非荷重部と荷重部の軟骨修復の違い : 非荷重部と荷重部の軟骨修復の違い

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　関節軟骨の全層欠損損傷は自然に修復されることが知られているが、軟骨再生については不明な点が多く、修復組織に関して一致した見解は得られていない。そこで本研究では、軟骨治療手術の一つであるMicrofractureを応用することで軟骨全層欠損モデルを作成する事を試み、大腿骨内顆非荷重部および荷重部の軟骨修復の過程を組織学的に検討した。　対象として９週齢Wistar系雄性ラット６０匹を用い、関節包上から左大腿骨内顆非荷重部もしくは荷重部にワイヤーを用いて穿孔を行った。飼育期間後、組織標本を作製し、ヘマトキシリン・エオジン染色を行い、光学顕微鏡下で病理組織学的に観察した。　非荷重部損傷群は１週、２週、４週後に無腐性壊死を伴う硝子軟骨組織により修復されたが、８週後には全例で線維軟骨様組織による修復となった。荷重部損傷群では１週、２週、４週後とも非荷重部損傷群と類似した修復状態であったが、８週後では正常な関節軟骨に類似した硝子軟骨組織によって修復された。　本結果より、非荷重部と荷重部の軟骨修復に差異があることが示唆され、この要因として損傷部位の違いが大きく影響していると考えられた。つまり、荷重や関節運動の有無に加えて、非荷重部と荷重部軟骨に存在する元来の組織学的な相違、例えば、軟骨細胞の数や軟骨層の厚さ、軟骨代謝の程度、荷重などの力学的負荷に対する耐久性、滑液循環量の違いなどが修復能に影響を及ぼしていることが推測された。 It is known that a full-thickness articular cartilage defect is spontaneouslyrepaired. However, the mechanisms of articular cartilage regeneration remainsunclear, and the consistent opinions about the repair tissue are not obtained. Inthis study, we tried to produce a rat full-thickness articular defects model byapplying Microfracture, known as one of the operative treatments for the cartilageinjury. And we histopathologically studied the cartilage regeneration at theunloading and loading portion in a medial condyle of the femur.　We used sixty Wistar male rats of 9-week-old. Under anesthesia, thirty rats waspenetrated the unloading portion in a medial condyle of the left femur over thecapsule by a Kirschner wire (Group U). The other thirty rats was penetrated theloading portion (Group L). Both groups were divided into immediacy, 1, 2, 4, 8weeks(n=6). After the experimental period, the knee joints of each group were excisedand stained with hematoxylin-eosin. We observed them under an opticalmicroscope. The experimental protocol was approved by the Committee for AnimalExperimentation at Kanazawa University.　In the group U, the repair tissues were hyaline-like tissue with aseptic necrosisand chondrocyte cloning from 1week to 4weeks, but at 8weeks the repair tissueswere replaced with fibrocartilage-like tissue with blood vessels. In the group L, therepair tissues were hyaline-like tissue with aseptic necrosis and chondrocyte cloningfrom 1week to 4weeks, as well as group U. At 8weeks, the repair tissues weremaintained hyaline tissue, which is similar with normal articular cartilage.　These results suggest that the cartilage regeneration has difference betweenunloading portion and loading portion. This difference in repair tissue may beinfluenced on the difference in the portion of the cartilage detect. In other words,besides the loading and the joint motion, the primary histological difference inbetween unloading portion and loading portion, for example, the number ofchondrocytes, the thickness of cartilage, the degree of cartilage metabolism, theendurance for mechanical stress, and the amount of synovial fluid circulation mayeffect on cartilage repair.　In the future, in prerequisite condition for the increase of specimens and thequantitative assessment of repair tissue, it is necessary that articular cartilageregeneration is studied in long term.
2010-07-30

非荷重部と荷重部の軟骨修復の違い : 非荷重部と荷重部の軟骨修復の違い

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