Mechano Growth Factor Accelerates ACL Repair and Improves Cell Mobility of Mechanically Injured Human ACL Fibroblasts by Targeting Rac1-PAK1/2 and RhoA-ROCK1 Pathways

Abstract

Exceeded mechanical stress leads to a sublethal injury to anterior cruciate ligament (ACL) fibroblasts, and it will hinder cell mobility and ACL regeneration, and even induce osteoarthritis. The mechano growth factor (MGF) could be responsible for mechanical stress and weakening its negative effects on cell physiological behaviors. In this study, effects of MGF on cell mobility and relevant molecules expression in injured ACL fibroblasts were detected. After an injurious mechanical stretch, the analysis carried out, at 0 and 24 h, respectively, showed that the cell area, roundness, migration, and adhesion of ACL fibroblasts were reduced. MGF (10, 100 ng/mL) treatment could improve cell area, roundness and promote cell migration and adhesion capacity compared with the injured group without MGF. Further study indicated that cell mobility-relevant molecules (PAK1/2, Cdc42, Rac1, RhoA, and ROCK1) expression in ACL fibroblasts was down-regulated at 0 or 24 h after injurious stretch (except Rac1 and RhoA at 0 h). Similarly, MGF improved cell mobility-relevant molecule expression, especially the ROCK1 expression level in ACL fibroblasts at 0 or 24 h after injurious stretch. Protein expression of ROCK1 in injured ACL fibroblasts was also reduced and could be recovered by MGF treatment. In a rabbit partial ACL transection (ACLT) model, ACL exhibited poor regenerative capacity in collagen and extracellular matrix (ECM) synthesis after partial ACLT for 2 or 4 weeks, and MGF remarkably accelerated ACL regeneration and restored its mechanical loading capacity after partial ACLT for four weeks. Our findings suggest that MGF weakens the effects of pathological stress on cell mobility of ACL fibroblasts and accelerates ACL repair, and might be applied as a future treatment approach to ACL rupture in the clinic.

Dehydrocorydaline Accelerates Cell Proliferation and Extracellular Matrix Synthesis of TNFα-Treated Human Chondrocytes by Targeting Cox2 through JAK1-STAT3 Signaling Pathway

“…Protein expression levels of p-JAK1 and p-STAT3 in the normal group, the TNFα group, and the TNFα + 10 µM DHC group were detected with ICF staining according to our previous study [3]. The samples were incubated with the primary antibodies anti-STAT3 (phospho Y705) (Abcam, Cambridge, MA, USA, 1:300) and anti-JAK1 (phospho Tyr1022) (Cell Signaling Technology, Beverly, MA, USA, 1:50) overnight at 4 • C. Then, the cells were incubated with FITC-conjugated secondary antibody (Beyotime, Shanghai, China, 1:300) for 1 h at room temperature (RT).…”

“…The cartilage can therefore buffer the mechanical stress between the tibia and femur during exercise and decrease friction [1]. Aging and aberrant mechanical load-caused anterior cruciate ligament (ACL) rupture will lead to the cell loss of chondrocytes and extracellular matrix (ECM) degradation in articular cartilage and further cause osteoarthritis (OA) [2,3]. Once OA occurs, inflammatory factors are highly expressed and pervasive in the synovial fluid, and then the matrix metalloproteinases 2 of 18 (MMPs) is activated, further adding to the degradation of ECM [4,5].…”

Cell Death in Acute Organ Injury and Fibrosis

“…For example, excessive mechanical stress, aging, or hypoxia can cause sublethal injury or the apoptosis of anterior cruciate ligament fibroblasts, hindering fibroblast cell motility and ligament regeneration [30]. An improvement in fibroblast motility or survival has been shown to protect and accelerate the healing of the anterior cruciate ligament [31][32][33]. In addition, components of extracellular matrix proteins may also be important to protect some organ normal resident cells from injury and apoptosis.…”