Acupuncture increases the diameter and reorganisation of collagen fibrils during rat tendon healing.

BACKGROUND: Our previous study showed that electroacupuncture (EA) increases the concentration and reorganisation of collagen in a rat model of tendon healing. However, the ultrastructure of collagen fibrils after acupuncture is unknown. OBJECTIVES: To assess the effect of acupuncture protocols on the ultrastructure of collagen fibrils during tendon healing. METHODS: Sixty-four rats were divided into the following groups: non-tenotomised (normal group), tenotomised (teno group), tenotomised and subjected to manual acupuncture at ST36 (ST36 group), BL57 (BL57 group) and ST36+BL57 (SB group) and EA at ST36+BL57 (EA group). The mass-average diameter (MAD) and the reorganisation of collagen fibril diameters were determined during the three phases of tendon healing (at 7, 14 and 21 days). RESULTS: The MAD increased during the three phases of healing in the SB group. In the EA group, MAD increased initially but was reduced at day 21. The reorganisation of collagen fibrils was improved in the EA and SB groups at days 14 and 21, respectively. EA at day 21 appeared to reduce the reorganisation. CONCLUSIONS: These results indicate that the use of EA up to day 14 and manual acupuncture at ST36+BL57 up to day 21 improve the ultrastructure of collagen fibrils, indicating strengthening of the tendon structure. These data suggest a potential role for acupuncture in rehabilitation protocols.

Statins induce biochemical changes in the Achilles tendon after chronic treatment.

Statins have been widely prescribed as lipid-lowering drugs and are associated with tendon rupture. Therefore, this study aimed to evaluate the possible biochemical changes in the Achilles tendon of rats after chronic treatment with statins. Dosages of statins were calculated using allometric scaling with reference to the 80mg/day and 20mg/day, doses recommended for humans. The rats were divided into the following groups: treated with simvastatin (S-20 and S-80), treated with atorvastatin (A-20 and A-80), and the control group that received no treatment (C). Measurements of low-density lipoprotein (LDL) in the plasma were performed. The levels of non-collagenous proteins, glycosaminoglycans (GAGs) and hydroxyproline were quantified. Western blotting for collagen I was performed, and the presence of metalloproteinases (MMPs)-2 and -9 was investigated through zymography. The concentration of non-collagenous proteins in S-20 was less than the C group. There was a significant increase in pro-MMP-2 activity in A-80 group and in active MMP-2 in S-20 group compared to the C group. A significant increase in latent MMP-9 activity was observed in both the A-80 and S-20 groups when compared to C group. In the A-20 group, there was a lower amount of collagen I in relation to C group. In addition, a higher concentration of hydroxyproline was found in the S-20 group than the C group. The analysis of GAGs showed a significant increase in the A-20 group when compared to C group. The treatment induced remarkable alterations in the Achilles tendon and the response of the tissue seems to depend of the used statin dosage. The presence of MMP-2 and MMP-9 is evidence of the degradation and remodeling processes in the extracellular matrix of the tendons. Our results show that statins induce imbalance of extracellular matrix components and possibly induce microdamage in tendons.

Inflammatory process induced by carrageenan in adjacent tissue triggers the acute inflammation in deep digital flexor tendon of rats.

Tendinopathy is a pathology found mainly in the rotator cuff, patellar, Achilles and flexor tendons. Tendinopathy is a significant impediment to performance in athletes and in workers in the labor market. Some studies have indicated that inflammation in adjacent tissues may affect the rotator cuff and Achilles tendon. In this study alterations were verified in the extracellular matrix (ECM) of the deep digital flexor tendon after two periods (12 and 24 hr) of induction inflammation in rat paw. Wistar rats were divided into three groups: those that received injection of 1% carrageenan; those that received 0.9% NaCl; and those that received no application. The tendon was divided into distal (d), proximal (p), and intermediate (i) regions. Biochemical analyses were performed and included non-collagenous proteins (NCP), glycosaminoglycans (GAGs), hydroxyproline (HoPro) and metalloproteinases 2 and 9. Tissue sections were stained with toluidine blue, hematoxylin-eosin, and Ponceau SS and observed under polarization microscopy. Remarkable results were detected that included the presence of MMP-9, degradation of NCP and GAG and the presence of cellular infiltrate closer to digits in d region. The different concentrations of HoPro, as well as alterations in the organization of the collagen fibers showed the collagenous matrix undergoing some alterations. The results indicated that the induced inflammation in rat paw exhibited characteristics similar to the typical acute inflammatory process observed in tendons.

Electroacupuncture increases the concentration and organization of collagen in a tendon healing model in rats.

The aim of this study was to investigate the effect of electroacupuncture (EA) on the composition and organization of the extracellular matrix of the rat Achilles tendon after a partial transection during the proliferative phase of healing. Wistar rats were divided into three groups: rats that were not tenotomized (G1), tenotomized rats (G2), and rats that were tenotomized and submitted to EA (G3). EA was applied 15 days after injury at the ST36 and BL57 acupoints for 20 min, three times per week on alternate days for a total of six sessions. Biochemical analyses were performed using non-collagenous proteins, glycosaminoglycans, and hydroxyproline quantifications. An analysis of metalloproteinase-2 was carried out by zymography. The general organization of the extracellular matrix and the metachromasy of the tendons were analyzed under light microscopy. The organization of the bundles of collagen fibers was analyzed by birefringence analysis. The results showed that EA did not alter the concentration of non-collagenous proteins or glycosaminoglycans or the enzymatic activity of metalloproteinase-2 in the transected tendons. However, the concentration of hydroxyproline was significantly increased when these tendons were treated by EA. The analysis of birefringence showed a higher organization of collagen fibers in the group treated by EA. These results indicate, for the first time, that EA may offer therapeutic benefits for the treatment of tendon injuries by increasing the concentration of collagen and by inducing a better molecular organization of the collagen fibers, which may improve the mechanical strength of the tendon after injury.

Alterations in the Achilles tendon after inflammation in surrounding tissue.

OBJECTIVE: To analyze the characteristics of the Achilles tendon of rats after induction of localized inflammation in the rat paw. METHODS: IN OUR STUDY THREE GROUPS WERE USED: inflamed group with carrageenan in rat paw (G1); saline group (G2) and control group (G3). After 4 hours the animals were euthanized and the Achilles tendon removed. RESULTS: No significant differences were observed in the analysis of non-collagenous proteins, glycosaminoglycans and hydroxyproline in the groups but a tendency of reduction was verified in G1. As regards the organization of collagen molecules, no differences were observed between groups. With respect to MMPs activity, a stronger presence of the active isoform of MMP-2 in G1 was observed, suggesting that the remodeling was occurring. CONCLUSION: Thus, we conclude that the inflammatory process in rat paw may affect the remodeling of tendons located near the inflamed site. Level of Evidence I, Prognostic Studies - Investigating the Effect of a Patient Characteristic on the Outcome of Disease.

Effects of acute inflammation induced in the rat paw on the deep digital flexor tendon.

The tendon is commonly affected by inflammation, and in such situations, the tissue undergoes a process of reorganization of the extracellular matrix to improve and regenerate the affected region. Little is known about the mechanisms that trigger inflammation in the tissues surrounding the affected area. The objective of this study was to biochemically and morphologically analyze the deep digital flexor tendon at the peak of acute inflammation in the rat paw. Wistar rats were divided into the following three groups: those that received injection of 1% carrageenan, those that received 0.9% NaCl, and those that received nothing. The deep digital flexor tendon was divided into the distal, proximal, and intermediate regions. For biochemical analysis, the tendons were treated with guanidine hydrochloride and analyzed by sodium dodecyl sulfate-polyacrilamide gel electrophoresis. Proteins, glycosaminoglycans (GAGs), and hydroxyproline were quantified, and metalloproteinases were analyzed. The GAGs were analyzed by agarose gel electrophoresis. Tissue sections were stained with hematoxylin-eosin, toluidine blue, and Ponceau SS. The content of proteins and GAGs was smaller in the group receiving the application of carrageenan. The concentration of hydroxyproline in the two tendon regions that respond to tension forces was higher in the inflammation group. The metalloproteinase-9 was detected in the distal region, and a thicker epitenon with cellular infiltrate was observed in the groups with inflamed paws. Meanwhile, a better organization of collagen bundles was observed in the two tension regions of that same group. Our results show that although the tendon was not directly inflamed, changes in the surrounding structural and biochemical parameters were observed.