title: Ectopic chondro-ossification and erroneous extracellular matrix deposition in a tendon window injury model.
abstract: The acquisition of chondro-osteogenic phenotypes and erroneous matrix deposition may account for poor tissue quality after acute tendon injury. We investigated the presence of chondrocyte phenotype, ossification, and the changes in the expression of major collagens and proteoglycans in the window wound in a rat patellar tendon window injury model using histology, von Kossa staining and immunohistochemistry of Sox 9, major collagens, and proteoglycans. Our results showed that the repair tissue did not restore to normal after acute injury. Ectopic chondrogenesis was observed in 33% of samples inside wound at week 4 while ectopic ossification surrounded by chondrocyte-like cells were observed in the window wound in 50% of samples at week 12. There was sustained expression of biglycan and reduced expression of aggrecan and decorin in the tendon matrix in the repair tissue. The erroneous deposition of extracellular matrix and ectopic chondro-ossification in the repair tissue, both might influence each other, might account for the poor tissue quality after acute injury. Higher expression of biglycan and aggrecan were observed in the ectopic chondro-ossification sites in the repair tissue, suggesting that they might have roles in ectopic chondro-osteogenesis.
authors.affiliation: Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR, China. pauline@ort.cuhk.edu.hk
authors.forename: Pauline Po Yee
authors.initials: PP
authors.lastname: Lui
authors.forename: Yau Chuk
authors.initials: YC
authors.lastname: Cheuk
authors.forename: Yuk Wa
authors.initials: YW
authors.lastname: Lee
authors.forename: Kai Ming
authors.initials: KM
authors.lastname: Chan
mesh_terms: D053674:Aggrecans / Q000378:metabolism; D000818:Animals; D058578:Biglycan / Q000378:metabolism; D019902:Chondrocytes / Q000378:metabolism / Q000473:pathology; D024042:Collagen Type I / Q000378:metabolism; D024061:Collagen Type III / Q000378:metabolism; D058575:Decorin / Q000378:metabolism; D004195:Disease Models, Animal; D005109:Extracellular Matrix / Q000378:metabolism / Q000473:pathology*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D000071235:Fibromodulin; D008297:Male; D009999:Ossification, Heterotopic / Q000473:pathology*; D017847:Patellar Ligament / Q000293:injuries* / Q000378:metabolism / Q000473:pathology*; D010641:Phenotype; D011509:Proteoglycans / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013708:Tendon Injuries / Q000378:metabolism / Q000473:pathology*; D014945:Wound Healing / Q000502:physiology
chemical_list: C508321:Acan protein, rat; D053674:Aggrecans; D058578:Biglycan; D024042:Collagen Type I; D024061:Collagen Type III; D058575:Decorin; D016326:Extracellular Matrix Proteins; C000604334:Fmod protein, rat; D011509:Proteoglycans; D000071235:Fibromodulin