Dataset Information

Distinctive collagen maturation process in fibroblasts derived from rabbit anterior cruciate ligament, medial collateral ligament, and patellar tendon in vitro.

ABSTRACT:

Purpose

Differences in the tissue-specific collagen maturation process between tendon and ligament are still unknown. Collagen cross-link formation is crucial for the collagen maturation process. The aim of this study is to examine collagen maturation processes of anterior cruciate ligament (ACL), medial collateral ligament (MCL), and patellar tendon (PT) in vitro, in order to determine the optimal cell source for tissue engineering of ligament.

Methods

Cells derived from the ACL, MCL, and PT of New Zealand white rabbits were isolated. Each cell type was cultured for up to 4 weeks after reaching confluence. Cell-matrix layers were evaluated and compared for their morphology, collagen cross-links, and gene expression levels of lysine hydroxylase 1 and 2, lysyl oxidase (LOX), tenomodulin, collagen1A1 (Col1A1), and collagen3A1 (Col3A1).

Results

Transmission electron microscopy photomicrographs verified that collagen fibrils were secreted from all three types of fibroblasts. A higher ratio of dihydroxylysinonorleucine/hydroxylysinonorleucine was evident in the ligament compared to the tendon, which was consistent with lysine hydroxylase 2/lysine hydroxylase 1 gene expression. The gene expression of LOX, which regulates the total amount of enzymatic cross-linking, and the gene expression levels of Col1A1 and Col3A1 were higher in the ACL matrix than in the MCL and PT matrices.

Conclusion

ACL, MCL, and PT cells have distinct collagen maturation processes at the cellular level. In addition, the collagen maturation of ACL cells is not necessarily inferior to that of MCL and PT cells in that all three cell types have a good ability to synthesize collagen and induce collagen maturation. This bioactivity of ACL cells in terms of ligament-specific mature collagen induction can be applied to tissue-engineered ACL reconstruction or remnant preserving procedure with ACL reconstruction.

SUBMITTER: Kato S

PROVIDER: S-EPMC4555208 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:Both the anterior cruciate ligament (ACL) and the medial collateral ligament (MCL) bear load during athletic tasks of landing, cutting, pivoting, and twisting. As dynamic knee valgus is a purported mechanism for ACL injury, the MCL should bear significant strain load with valgus force. HYPOTHESIS:The intact MCL will demonstrate a significant increase in strain upon failure of the ACL at 25° of knee flexion. STUDY DESIGN:Controlled laboratory study. METHODS:In vivo kinetics/kinematics of 44 healthy athletic participants were measured to determine stratification of injury risk (ie, low, medium, and high) in 3 degrees of knee forces/moments (knee abduction moment, anterior tibial shear, and internal tibial rotation). These stratified kinetic values were input into a cadaveric impact simulator to assess ligamentous strain during a simulated landing task. Uniaxial and multiaxial load cells and differential variable reluctance transducer strain sensors were utilized to collect mechanical data for analysis. Conditions of external loads applied to the cadaveric limbs were varied and randomized. RESULTS:ACL strain increased with increased dynamic knee abduction moment (?2[5] = 14.123, P = .0148). The most extreme dynamic knee abduction moment condition demonstrated significantly higher ACL strain compared with lower loaded trials (P? .0203). Similarly, MCL strain increased with dynamic knee abduction moment (?2[5] = 36.578, P < .0001). Matched-pairs analysis compared ACL strain with MCL strain (maximum ACL strain - maximum MCL strain) and demonstrated high strain for the ACL versus the MCL (S177 = 6223.5, P < .0001). CONCLUSION:Although significant, MCL strain had minimal increase with increased dynamic knee abduction moment, and the event of ACL failure did not significantly increase MCL strain when compared with high dynamic knee abduction moment conditions in the cadaveric model. The ACL bears more strain than the MCL at increasing amounts of dynamic knee abduction moment at 25° of knee flexion, which may explain the limited concomitant MCL injury rate that can occur during a dynamic valgus collapse of the knee. CLINICAL RELEVANCE:These characteristics of ACL and MCL strain are important to understand the mechanisms that drive these injuries at the knee and will improve rehabilitation and injury prevention techniques.