Relaxin inhibits patellar tendon healing in rats: a histological and biochemical evaluation

Abstract

Background Female patients are more likely to have tendon injuries than males, especially those who has a higher concentration of relaxin. Previous studies have demonstrated that relaxin attenuates extracellular matrix (ECM) formation. However, the mechanism of relaxin on tendon repair remains unclear. We hypothesize that relaxin inhibits tendon healing by disrupting collagen synthesis. Methods A patellar tendon window defect model was established using Sprague-Dawley rats. The center of the patellar tendon was removed from the patella distal apex and inserted to the tibia tuberosity in width of 1 mm. Then, the rats were injected with saline (0.2 μg/kg/day) or relaxin (0.2 μg/kg/day) for two and four weeks, which was followed by biomechanical analysis and histological and histochemical examination. Results Mechanical results indicated that relaxin induces a significant decrease in tear resistance, stiffness, and Young’s modulus compared to those rats without relaxin treatment. In addition, it was shown that relaxin activates relaxin family peptide receptor 1(RXFP1), disturbs the balance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteases (TIMPs), and reduces the deposition of collagen in injury areas. Conclusions Relaxin impairs tendon healing in rats. Also, relaxin might lead to tendon injury more commonly for females than males. Electronic supplementary material The online version of this article (10.1186/s12891-019-2729-3) contains supplementary material, which is available to authorized users.

Role of relaxin in diastasis of the pubic symphysis peripartum

“…RLX also reduces the degree of scar formation[ 18 ]. Unemori et al [ 19 ] and Mookerjee et al [ 20 ] found that RLX inhibited the differentiation of renal fibroblasts and collagen deposition by inhibiting phosphorylation of Smad2, thus interfering with TGF-β1[ 21 , 22 ]. An increase in RLX levels also causes ligament and tendon injury.…”

Dual‐Phase Aligned Composite Scaffolds Loaded with Tendon‐Derived Stem Cells for Achilles Tendon Repair

“…With the aging of the population and the increase in physical activity, the incidence of tendon injury has increased significantly. According to conservative reports, more than 30 million tendon injuries occur worldwide each year, [ 4 ] which represent a serious societal problem that must be addressed.…”

The Role of Scaffolds in Tendon Tissue Engineering

“…Within the orthopaedic field, tendinopathy is one of the most frequently self reported musculoskeletal injuries in the athletic and working populations, which result in pain, swelling and impaired function [ 2 ]. More than 30 million tendon injuries are reported annually worldwide, while the actual number might be even higher since many injuries are not reported [ 3 ]. The elderly population and athletes are predominantly affected by tendon injuries.…”