Lubricin distribution in the torn human anterior cruciate ligament and meniscus

Abstract

The objective of this study was to: (1) determine the distribution of lubricin in the human torn anterior cruciate ligament (ACL) and meniscus; (2) determine the distribution of lubricin in the human intact ACL and meniscus; (3) and identify potential cellular sources of lubricin in these tissues. Ten torn ACLs and six torn menisci were obtained from surgeries; for comparison, 11 intact ACLs and 13 intact menisci were obtained from total knee replacements. Samples were formalin fixed and processed for immunohistochemical staining with a monoclonal antibody for lubricin. In torn ACLs and menisci, lubricin was generally found as a discrete layer covering the torn surface. No surface lubricin staining was found on the transected edges produced during excision. Lubricin was also found on the native surfaces of intact ACLs and menisci. In all tissues, lubricin was found in the matrix and intracellularly.

Aging affects mechanical properties and lubricin/PRG4 gene expression in normal ligaments

“…This was first suggested by Funakoshi and Spector (2010) in a caprine infraspinatus tendon cell culture study, and then later supported by Zhang et al (2011) in an analysis of human ACL and menisci. Zhao et al (2010) demonstrated that repaired canine flexor tendons treated with a lubricin-containing hyaluronic acid compound showed decreased post-operative adhesions, but this was also associated with impaired tendon healing.…”

“…articular cartilage, meniscus, and tendon (Sun et al, 2006;Lee et al, 2008;Funakoshi et al, 2008;Zhang et al, 2011). Lee et al (2008) reported that bovine ACLs and posterior cruciate ligaments (PCLs) stained for lubricin/PRG4 on their surface, as well as between collagen fibre bundles.…”

“…Jay (1992) was the first to define the role of lubricin as a boundary lubricant in animal synovial joints. Since then, lubricin has been identified in canine, bovine, and human knee ligaments (Sun et al, 2006;Lee et al, 2008;Zhang et al, 2011). Because lubricin has been found on the surface of ligaments and between collagen fibre bundles in ligaments, it is thought to serve as both a surface lubricant as well as an interfascicular lubricant in ligaments (Lee et al, 2008).…”

Influence of cartilage interstitial fluid on gene expression in cruciate ligament fibroblasts

“…Many articles refer to the fibroblast gene expression of the ligaments in damaged or pathological joints (20,21,23,24). Our study shows the influence of factors present in normal joint fluid on the gene expression in ACL fibroblasts.…”

“…Lubricin was also found on the native surfaces of intact ACLs and on torn edges of ACLs. Thus, it may interfere with the integrative healing process needed for ACL repair (21). Both CIF and CIF-like cocktail stimulated aggrecan expression in CLFs but not in DFs (Tables I and II).…”