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ACL transection influences mRNA levels for collagen type I and TNF‐α in MCL scar
Author(s) -
Majima Tokifumi,
Lo Ian K. Y.,
Randle John A.,
Marchuk Linda L.,
Shrive Nigel G.,
Frank Cyril B.,
Hart David A.
Publication year - 2002
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1016/s0736-0266(01)00128-0
Subject(s) - decorin , biglycan , anterior cruciate ligament , scars , lumican , medial collateral ligament , medicine , extracellular matrix , glyceraldehyde 3 phosphate dehydrogenase , acl injury , ligament , messenger rna , gene expression , ankle , pathology , anatomy , chemistry , proteoglycan , cartilage , gene , biochemistry
To assess the mRNA expression of extracellular matrix genes which might correlate with or contribute to mechanically weaker medial collateral ligament (MCL) scars in the ACL‐deficient rabbit knee joint compared to those in anterior cruciate ligament (ACL) intact knee joints, a bilateral MCL injury was induced in 10 skeletally mature female NZW rabbits. As part of the same surgical procedure, the ACL was transected in one of the knees while the contralateral knee had a sham procedure. The side having the combined MCL and ACL injury was randomly assigned. After six weeks, the rabbits were euthanized. Histological assessments were performed on samples of the MCL scars from each operated knee ( n = 3 animals) and mRNA levels for collagen type I, III, V, decorin, biglycan, lumican, fibromodulin, TGF‐β, IL‐1, TNF‐α, MMP‐1, MMP‐1, MMP‐13, and a housekeeping gene (GAPDH) were assessed using semiquantitative RT‐PCR on RNA isolated from the MCL scar tissue of the remaining animals ( n = 7 animals). Levels of mRNA for each gene were normalized using the corresponding GAPDH value. Results showed that the total RNA yield (per mg wet weight) in the MCL scar of the ACL‐deficient knee was significantly greater than that in the MCL scar from the ACL‐intact knee. Collagen type I mRNA levels were significantly lower and mRNA levels for TNF‐α were significantly greater in the scars of ACL‐deficient knees compared to scars from ACL‐intact joints. There were no significant differences between ACL‐deficient and ACL‐intact knees with respect to MCL scar mRNA levels for the remaining genes assessed. Histologically, the “flaw” area, which has been shown to correlate with mechanical properties in previous studies, was significantly greater in MCL scars from ACL‐deficient knees than in the ACL‐intact MCL scars. The mean number of cells/mm 2 in MCL scars from ACL‐deficient knees was significantly greater than in MCL scars from ACL‐intact knees. The present study suggests that MCL scar cell metabolism is differentially influenced by the combined injury environment. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.