Use of Platelet-Rich Plasma Plus Suramin, an Antifibrotic Agent, to Improve Muscle Healing After Injuries.

BACKGROUND: The increasing use of platelet-rich plasma (PRP) to treat muscle injuries raises concerns because transforming growth factor-beta (TGF-ß) in PRP may promote fibrosis in the injured muscle and thus impair muscle regeneration. PURPOSE: To investigate whether suramin (a TGF-ß inhibitor) can reduce muscle fibrosis to improve healing of the injured muscle after PRP treatment and identify the underlying molecular mechanism. STUDY DESIGN: Controlled laboratory study. METHODS: Myoblasts isolated from the gastrocnemius muscle of Sprague Dawley rats were treated with PRP or PRP plus suramin. MTT assays were performed to evaluate cell viability. The expression of fibrosis-associated proteins (such as type I collagen and fibronectin), Smad2, and phosphorylated Smad2 was determined using Western blot analysis and immunofluorescent staining. An anti-TGF-ß antibody was employed to verify the role of TGF-ß in fibronectin expression. Gastrocnemius muscles were injured through a partial transverse incision and then treated using PRP or PRP plus suramin. Hematoxylin and eosin staining was conducted to evaluate the healing process 7 days after the injury. Immunofluorescent staining was performed to evaluate fibronectin expression. Muscle contractile properties-fast-twitch and tetanic strength-were evaluated through electric stimulation. RESULTS: PRP plus 25 µg/mL of suramin promoted myoblast proliferation. PRP induced fibronectin expression in myoblasts, but suramin reduced this upregulation. The anti-TGF-ß antibody also reduced the upregulation of fibronectin expression in the presence of PRP. The upregulation of phosphorylated Smad2 by PRP was reduced by either the anti-TGF-ß antibody or suramin. In the animal study, no significant difference was discovered in muscle healing between the PRP versus PRP plus suramin groups. However, the PRP plus suramin group had reduced fibronectin expression at the injury site. Fast-twitch strength and tetanic strength were significantly higher in the injured muscle treated using PRP or PRP plus suramin. CONCLUSION: Simultaneous PRP and suramin use reduced fibrosis in the injured muscle and promoted healing without negatively affecting the muscle's contractile properties. The underlying molecular mechanism may be associated with the phosphorylated Smad2 pathway. CLINICAL RELEVANCE: Simultaneous PRP and suramin use may reduce muscle fibrosis without compromising muscle contractile properties and thus improve muscle healing.

Gonadotropin-releasing hormone antagonist associated with lower cardiovascular risk compared with gonadotropin-releasing hormone agonist in prostate cancer: A nationwide cohort and in vitro study.

BACKGROUND: We aimed to determine whether cardiovascular (CV) risk in patients with prostate cancer (PCa) differs between those who receive gonadotropin-releasing hormone (GnRH) agonist (GnRHa) therapy and those who receive GnRH antagonist therapy. METHODS: Using the Taiwan National Health Insurance Research Database, we analyzed data by comparing 666 participants receiving GnRH antagonists and 1332 propensity score-matched participants treated with GnRHa in a 1:2 fashion during the period from May 1, 2015, to September 30, 2018. Cox proportional-hazards models were used to estimate the treatment effect on CV outcomes. Furthermore, we conducted an in vitro study to investigate the effect of a GnRHa (leuprolide) or a GnRH antagonist (degarelix) on matrix metalloproteinase-9 (MMP-9) expression and invasion ability in THP-1 differentiated macrophages. RESULTS: GnRH antagonist therapy was associated with a lower risk of composite CV events of myocardial infarction, ischemic stroke, or CV death (hazard ratio [HR], 0.48; 95% confidence interval [CI], 0.25-0.90) than GnRHa therapy, with a mean follow-up period of 1.21 years. Significantly lower risks of CV death (HR, 0.21; 95% CI, 0.06-0.70) and all-cause mortality (HR, 0.77; 95% CI, 0.61-0.97) were observed in the GnRH antagonist group. In the in vitro study, leuprolide, but not degarelix, significantly increased the expression of MMP-9 activity and the invasive ability of THP-1 differentiated macrophages through gelatin zymography and the matrix invasion assay, respectively. CONCLUSION: GnRH antagonists were associated with reduced risk CV events compared with the GnRHa among patients with PCa, which may be through effects on macrophages.

Platelet-Rich Plasma Releasate Promotes Regeneration and Decreases Inflammation and Apoptosis of Injured Skeletal Muscle.

BACKGROUND: Platelet-rich plasma (PRP) contains various cytokines and growth factors that may be beneficial to the healing process of injured muscle. Based on the authors' previous study, PRP releasate can promote proliferation and migration of skeletal muscle cells in vitro, so animal studies are performed to support the use of PRP to treat muscle injury in vivo. PURPOSE: To investigate the effect of PRP releasate on regeneration of injured muscle, as well as its effect on inflammatory reaction and cell apoptosis, in the early stages of the muscle-healing process. STUDY DESIGN: Controlled laboratory study. METHODS: The gastrocnemius muscles of Sprague-Dawley rats were injured by partial transverse incision and then treated with PRP releasate. Hematoxylin and eosin stain was used to evaluate the healing process of injured muscle at 2, 5, and 10 days after injury. TUNEL assay was used to evaluate the cell apoptosis of injured muscle after PRP releasate treatment. Immunohistochemistry was used to stain the CD68-positive cells during the healing process. Muscle contractile properties, including fast-twitch and tetanic strength, were evaluated by electric stimulation. RESULTS: The results revealed that PRP releasate treatment could enhance the muscle-healing process and decrease CD68-positive cells and apoptotic cells. Furthermore, the tetanic strength was significantly higher in injured muscle treated with PRP releasate. CONCLUSION: In conclusion, PRP releasate could enhance the healing process of injured muscle and decrease inflammatory cell infiltration as well as cell apoptosis. CLINICAL RELEVANCE: PRP promotes skeletal muscle healing in association with decreasing inflammation and apoptosis of injured skeletal muscle. These findings provide in vivo evidence to support the use of PRP to treat muscle injury.

Platelet rich plasma releasate promotes proliferation of skeletal muscle cells in association with upregulation of PCNA, cyclins and cyclin dependent kinases.

Platelet rich plasma (PRP) contains various cytokines and growth factors which may be beneficial to the healing process of injured muscle. The purpose of this study is to investigate the effect and molecular mechanism of PRP releasate on proliferation of skeletal muscle cells. Skeletal muscle cells intrinsic to Sprague-Dawley rats were treated with PRP releasate. Cell proliferation was evaluated by 3-[4,5-Dimethylthiazol- 2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay and immunocytochemistry with Ki-67 stain. Flow cytometric analysis was used to evaluate the cell cycle progression. Western blot analysis was used to evaluate the protein expressions of PCNA, cyclin E1, cyclin A2, cyclin B1, cyclin dependent kinase (cdk)1 and cdk2. The results revealed that PRP releasate enhanced proliferation of skeletal muscle cells by shifting cells from G1 phase to S phase and G2/M phases. Ki-67 stain revealed the increase of proliferative capability after PRP releasate treatment. Protein expressions including cyclin A2, cyclin B1, cdk1, cdk2 and PCNA were up-regulated by PRP releasate in a dose-dependent manner. It was concluded that PRP releasate promoted proliferation of skeletal muscle cells in association with the up-regulated protein expressions of PCNA, cyclin A2, cyclin B1, cdk1 and cdk2.

Low-level laser irradiation stimulates tenocyte proliferation in association with increased NO synthesis and upregulation of PCNA and cyclins.

Low-level laser therapy is commonly used to treat tendinopathy or tendon injury. Tendon healing requires tenocyte migration to the repair site, followed by proliferation and synthesis of the extracellular matrix. There are few evidence to elucidate that low-level laser promote tenocyte proliferation. This study was designed to determine the effect of laser on tenocyte proliferation. Furthermore, the association of this effect with secretion of nitric oxide (NO) and the expressions of proliferating cell nuclear antigen (PCNA) and cyclins D1, E, A, and B1 was investigated. Tenocytes intrinsic to rat Achilles tendon were treated with low-level laser (660 nm). Tenocyte proliferation was evaluated by MTT assay and immunocytochemistry with Ki-67 stain. NO in the conditioned medium was measured by ELISA. Western blot analysis was used to evaluate the protein expressions of PCNA and cyclins D1, E, A, and B1. The results revealed that tenocytes proliferation was enhanced dose dependently by laser. NO secretion was increased after laser treatment. PCNA and cyclins E, A, and B1 were upregulated by laser. In conclusion, low-level laser irradiation stimulates tenocyte proliferation in a process that is mediated by upregulation of NO, PCNA, and cyclins E, A, and B1.

Low-level laser irradiation stimulates tenocyte migration with up-regulation of dynamin II expression.

Low-level laser therapy (LLLT) is commonly used to treat sports-related tendinopathy or tendon injury. Tendon healing requires tenocyte migration to the repair site, followed by proliferation and synthesis of the extracellular matrix. This study was designed to determine the effect of laser on tenocyte migration. Furthermore, the correlation between this effect and expression of dynamin 2, a positive regulator of cell motility, was also investigated. Tenocytes intrinsic to rat Achilles tendon were treated with low-level laser (660 nm with energy density at 1.0, 1.5, and 2.0 J/cm(2)). Tenocyte migration was evaluated by an in vitro wound healing model and by transwell filter migration assay. The messenger RNA (mRNA) and protein expressions of dynamin 2 were determined by reverse transcription/real-time polymerase chain reaction (real-time PCR) and Western blot analysis respectively. Immunofluorescence staining was used to evaluate the dynamin 2 expression in tenocytes. Tenocytes with or without laser irradiation was treated with dynasore, a dynamin competitor and then underwent transwell filter migration assay. In vitro wound model revealed that more tenocytes with laser irradiation migrated across the wound border to the cell-free zone. Transwell filter migration assay confirmed that tenocyte migration was enhanced dose-dependently by laser. Real-time PCR and Western-blot analysis demonstrated that mRNA and protein expressions of dynamin 2 were up-regulated by laser irradiation dose-dependently. Confocal microscopy showed that laser enhanced the expression of dynamin 2 in cytoplasm of tenocytes. The stimulation effect of laser on tenocytes migration was suppressed by dynasore. In conclusion, low-level laser irradiation stimulates tenocyte migration in a process that is mediated by up-regulation of dynamin 2, which can be suppressed by dynasore.

The effect of aging on migration, proliferation, and collagen expression of tenocytes in response to ciprofloxacin.

Quinolone-induced tendinopathy or tendon rupture tends to be age-related. However, the synergistic effects of quinolone and aging on tenocytes remained to be explored. Tenocytes intrinsic to rat Achilles tendon from two age groups (young: 2 months; and near senescent (old): 24 months) were treated with ciprofloxacin. Tenocyte migration and proliferation were assessed by transwell filter migration assay and MTT (3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay, respectively. Messenger RNA and protein expressions of types I and III collagen were determined by reverse transcription-polymerase chain reaction (RT/PCR) and Western blot analysis, respectively. Transwell filter migration assay revealed that ciprofloxacin inhibited tenocytes migration, which became more significant in old tenocytes (p < 0.05). The results of MTT assay revealed that tenocytes proliferation decreased after ciprofloxacin treatment (p < 0.05), which also became more significant in old tenocytes. The results of RT-PCR and Western blot analysis revealed that mRNA and protein expressions of type I collagen remained unchanged in either young or old tenocytes with ciprofloxacin treatment, whereas the expressions of type III collagen were down-regulated by ciprofloxacin, which was more significant in old tenocytes. In conclusion, aging potentiated the ciprofloxacin-mediated inhibition of migration, proliferation, and expression of type III collagen of tenocytes.

The promoting effect of pentadecapeptide BPC 157 on tendon healing involves tendon outgrowth, cell survival, and cell migration.

Pentadecapeptide BPC 157, composed of 15 amino acids, is a partial sequence of body protection compound (BPC) that is discovered in and isolated from human gastric juice. Experimentally it has been demonstrated to accelerate the healing of many different wounds, including transected rat Achilles tendon. This study was designed to investigate the potential mechanism of BPC 157 to enhance healing of injured tendon. The outgrowth of tendon fibroblasts from tendon explants cultured with or without BPC 157 was examined. Results showed that BPC 157 significantly accelerated the outgrowth of tendon explants. Cell proliferation of cultured tendon fibroblasts derived from rat Achilles tendon was not directly affected by BPC 157 as evaluated by MTT assay. However, the survival of BPC 157-treated cells was significantly increased under the H(2)O(2) stress. BPC 157 markedly increased the in vitro migration of tendon fibroblasts in a dose-dependent manner as revealed by transwell filter migration assay. BPC 157 also dose dependently accelerated the spreading of tendon fibroblasts on culture dishes. The F-actin formation as detected by FITC-phalloidin staining was induced in BPC 157-treated fibroblasts. The protein expression and activation of FAK and paxillin were determined by Western blot analysis, and the phosphorylation levels of both FAK and paxillin were dose dependently increased by BPC 157 while the total amounts of protein was unaltered. In conclusion, BPC 157 promotes the ex vivo outgrowth of tendon fibroblasts from tendon explants, cell survival under stress, and the in vitro migration of tendon fibroblasts, which is likely mediated by the activation of the FAK-paxillin pathway.

Ciprofloxacin up-regulates tendon cells to express matrix metalloproteinase-2 with degradation of type I collagen.

Ciprofloxacin-induced tendinopathy and tendon rupture have been previously described, principally affecting the Achilles tendon. This study was designed to investigate the effect of ciprofloxacin on expressions of matrix metalloproteinases (MMP)-2 and -9, tissue inhibitors of metalloproteinase (TIMP)-1 and -2 as well as type I collagen in tendon cells. Tendon cells intrinsic to rat Achilles tendon were treated with ciprofloxacin and then underwent MTT (tetrazolium) assay. Real-time reverse-transcription polymerase chain reaction (RT-PCR) and Western blot analysis were used, respectively, to evaluate the gene and protein expressions of type I collagen, and MMP-2. Gelatin zymography was used to evaluate the enzymatic activities of MMP-2 and -9. Reverse zymography was used to evaluate TIMP-1 and -2. Immunohistochemical staining for MMP-2 in ciprofloxacin-treated tendon explants was performed. Collagen degradation was evaluated by incubation of conditioned medium with collagen. The results revealed that ciprofloxacin up-regulated the expression of MMP-2 in tendon cells at the mRNA and protein levels. Immunohistochemistry also confirmed the increased expressions of MMP-2 in ciprofloxacin-treated tendon explants. The enzymatic activity of MMP-2 was up-regulated whereas that of MMP-9, TIMP-1 or TIMP-2 was unchanged. The amount of secreted type I collagen in the conditioned medium decreased and type I collagen was degraded after ciprofloxacin treatment. In conclusion, ciprofloxacin up-regulates the expressions of MMP-2 in tendon cells and thus degraded type I collagen. These findings suggest a possible mechanism of ciprofloxacin-associated tendinopathy.

Endothelium-dependent and -independent vasorelaxation induced by CIJ-3-2F, a novel benzyl-furoquinoline with antiarrhythmic action, in rat aorta.

AIMS: This study was designed to examine the mechanism of relaxation induced by CIJ-3-2F, a benzyl-furoquinoline antiarrhythmic agent, in rat thoracic aorta at the tissue and cellular levels. MAIN METHODS: Isometric tension of rat aortic ring was measured in response to drugs. Ionic channel activities in freshly dissociated aortic vascular smooth muscle cells (VSMCs) were investigated using a whole-cell patch-clamp technique. KEY FINDINGS: CIJ-3-2F relaxed both phenylephrine (PE) and high KCl (60mM)-induced contractions with respective pEC(50) (-log EC(50)) values of 6.91+/-0.07 and 6.32+/-0.06. Removal of endothelium or pretreatment with nitric oxide (NO)-pathway inhibitors N(omega)-nitro-l-arginine methyl ester (L-NAME), N(G)-monomethyl-l-arginine (L-NMMA), N(5)-(1-iminoethyl)-l-ornithine (L-NIO), hemoglobin, methylene blue or 1H-[1,2,4]oxadiazolo[4,2-alpha]quinoxalin-1-one (ODQ) reduced the relaxant effect of CIJ-3-2F. Relaxation to CIJ-3-2F was also attenuated by K(+) channel blockers tetraethylammonium (TEA) or 4-aminopyridine (4-AP), but not by charybdotoxin plus apamin, iberiotoxin, glibenclamide, or BaCl(2). CIJ-3-2F non-competitively antagonized the contractions induced by PE, Ca(2+), and Bay K8644 in endothelium-denuded rings. In addition, CIJ-3-2F inhibited both the phasic and tonic contractions induced by PE but did not affect the transient contraction induced by caffeine. CIJ-3-2F reduced the Ba(2+) inward current through L-type Ca(2+) channel (IC(50)=4.1microM) and enhanced the voltage-dependent K(+) (K(v)) current in aortic VSMCs. SIGNIFICANCE: These results suggest that CIJ-3-2F induced both endothelium-dependent and -independent vasorelaxation; the former is likely mediated by the NO/cGMP pathway whereas the latter is probably mediated through inhibition of Ca(2+) influx or inositol 1,4,5-triphosphate (IP(3))-sensitive intracellular Ca(2+) release, or through activation of K(v) channels.

Ibuprofen upregulates expressions of matrix metalloproteinase-1, -8, -9, and -13 without affecting expressions of types I and III collagen in tendon cells.

Nonsteroidal antiinflammatory drugs are widely used to treat sports-related tendon injuries or tendinopathy. This study was designed to investigate the effect of ibuprofen on expressions of types I and III collagen, as well as collagen-degrading enzymes including matrix metalloproteinase (MMP)-1, -2, -8, -9, and -13. Rat Achilles tendon cells were treated with ibuprofen and then underwent MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Reverse transcription-polymerase chain reaction was used to evaluate mRNA expressions of types I and III collagen, MMP-1, -2, -8, -9, and -13. Protein expressions of types I and III collagen, MMP-1, -8, and -13 were determined by Western blot analysis. Gelatin zymography was used to evaluate the enzymatic activities of MMP-2 and MMP-9. The results revealed that ibuprofen upregulated expressions of MMP-1, -8, -9, and -13, both at mRNA and protein levels. There was no effect of ibuprofen on mRNA and protein expressions of types I and III collagen. Gelatin zymography revealed that the enzymatic activity of MMP-9 was upregulated after ibuprofen treatment. In conclusion, ibuprofen upregulates the expressions of collagenases including MMP-1, -8, -9, and -13 without affecting the expressions of types I and III collagen. These findings suggest a molecular mechanism potentially accounting for the inhibition of tendon healing by ibuprofen.

Ciprofloxacin-mediated inhibition of tenocyte migration and down-regulation of focal adhesion kinase phosphorylation.

Ciprofloxacin-induced tendinopathy and tendon rupture have been previously described, principally affecting the Achilles tendon. However, the underlying mechanism remains unclear. Tendon healing requires migration of tenocytes to the repair site, followed by proliferation and synthesis of the extracellular matrix. This study was designed to determine the effect of ciprofloxacin on migration of tenocytes intrinsic to rat Achilles tendon. Whether a correlation exits between this effect and the expression and phosphorylation of focal adhesion kinase (FAK), which is a positive regulator of cell motility, was also investigated. Using cultured tenocytes, migration was evaluated by counting the number of initial cell outgrowth from the tendon explants and by transwell filter migration assay. Tenocyte spreading was also evaluated microscopically. The serum-induced protein expression and phosphorylation of FAK were determined by Western blot analysis in synchronized tenocytes. Ciprofloxacin dose-dependently inhibited tenocytes outgrowth from the explants ex vivo, migration of tenocytes through the transwell filter, as well as cell spreading in vitro. Suppression of FAK phosphorylation was revealed by Western blot analyses. In conclusion, ciprofloxacin inhibits tenocyte migration in a process that is probably mediated by inhibition of FAK phosphorylation.

Therapeutic ultrasound stimulation of tendon cell migration.

Ultrasound is a therapeutic agent commonly used to treat sports-related tendinopathy. Tendon healing requires tendon cells migration to the repair site, followed by the proliferation and synthesis of extracellular matrix. This study was designed to determine the effect of ultrasound on migration of tendon cells intrinsic to rat Achilles tendon. Furthermore, the existence of a correlation between this effect and the expression of the contractile actin isoform, alpha-smooth muscle (SM) actin, which is associated with cell mobility, was also examined. Cell migration was evaluated by transwell filter migration assay. The mRNA expressions of alpha-SM actin were determined by reverse transcription-polymerase chain reaction. Dose-dependent ultrasound enhancement of tendon cells migration through the transwell filter was demonstrated. Using immunofluorescence stain for alpha-SM actin, the percentages of alpha-SM actin-positive cells of total cells, nonmigrated cells, and migrated cells on the filter were calculated. Ultrasound-treated cells which had migrated to the bottom side of the filter were more likely to express alpha-SM actin than migrated control cells and nonmigrated cells. However, there was no change of mRNA and protein expression of alpha-SM actin as well as expression of FAK and p-FAK. In conclusion, ultrasound stimulates tendon cell migration in association with increased expression of alpha-SM actin of tendon cells.

The pentapeptide KTTKS promoting the expressions of type I collagen and transforming growth factor-beta of tendon cells.

Pentapeptide KTTKS, a subfragment of type I collagen propeptide, has been demonstrated to promote the extracellular release of collagen in fibroblasts. The present study was designed to investigate the effect and molecular mechanism of KTTKS on type I collagen expression of rat Achilles tendon cells. Genes related to the upregulation of collagen expression such as transforming growth factor-beta (TGF-beta), and mRNA-binding proteins (mRBP) E1 and K were also examined. MTT assay revealed cell viability was not affected by KTTKS treatment. Protein expression of type I collagen was determined by immunocytochemistry and Western blot analysis. Results showed that KTTKS induced type I collagen expression of tendon cells. The mRNA expressions of alpha1(I) procollagen, TGF-beta, mRBP K, as determined by reverse transcription-polymerase chain reaction (RT-PCR), were also enhanced after KTTKS treatment. The stability of preexisting alpha1(I) procollagen mRNA after the addition of alpha-amanitin was analyzed by RT-PCR at 24 and 48 h. Results showed that KTTKS slowed down the degradation of alpha1(I) procollagen mRNA (p = 0.021). Furthermore, the concentration of TGF-beta in conditioned medium, as determined by enzyme-linked immunosorbent assay, increased dose dependently in cells treated with KTTKS (p = 0.001). In conclusion, KTTKS promotes the expression of type I collagen and maintains its mRNA stability in a process associated with the upregulation of TGF-beta.

Ultrasound stimulation of types I and III collagen expression of tendon cell and upregulation of transforming growth factor beta.

Traumatic tendon injuries are commonly treated with ultrasound. However, previous research has not examined the molecular mechanism of this therapeutic effect on collagen synthesis of tendon cells. This study was designed to determine the effect of ultrasound on the expression of type I and type III collagen of tendon cells intrinsic to rat Achilles tendon. Whether a correlation exits between this effect and the expression of transforming growth factor beta (TGF-beta), which enhances collagen synthesis, was also investigated. Tendon cells after ultrasound treatment and protein expression of types I and III collagen were determined by immunocytochemistry. The mRNA expressions of alpha1(I) procollagen, alpha1(III) procollagen, and TGF-beta were determined by reverse transcription-polymerase chain reaction (RT-PCR). Furthermore, the concentration of TGF-beta in conditioned medium was evaluated by enzyme-linked immunosorbent assay (ELISA). Immunocytochemical staining revealed that ultrasound-treated tendon cells were stained more strongly for types I and III collagen than were control cells. Upregulation of procollagen alpha1(I) gene, procollagen alpha1(III) gene, and TGF-beta at the mRNA level was confirmed by RT-PCR. A dose-dependent increase in the concentration of TGF-beta in conditioned medium obtained from cells treated with ultrasound was demonstrated by ELISA assay (p = 0.043). In conclusion, ultrasound stimulates the expression of type I and type III collagen in a process that is likely mediated by the upregulation of TGF-beta.

Ibuprofen inhibition of tendon cell migration and down-regulation of paxillin expression.

Sports-related tendon injuries are commonly treated with nonsteroidal antiinflammatory drugs. Tendon healing requires migration of tendon cells to the repair site, followed by proliferation and synthesis of the extracellular matrix. This study was designed to determine the effect of ibuprofen on the migration of tendon cells intrinsic to rat Achilles tendon. Whether a correlation exits between this effect and the expression of paxillin, which is a positive regulator of cell spreading and migration, was also investigated. The migration of tendon cells was evaluated ex vivo by counting the number of initial outgrowths from the tendon explants and in vitro by transwell filter migration assay. The spreading of tendon cells in culture was also evaluated microscopically. The mRNA and protein expressions of paxillin were determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. Dose-dependent ibuprofen inhibition was demonstrated on the migration of tendon cells both ex vivo, and in vitro. Similar inhibition was also observed on the spreading of tendon cells. Suppression of mRNA expression and protein level of paxillin was revealed by RT-PCR and Western blot analyses. The expression of focal adhesion kinase (FAK) and tyrosine phosphorylation of FAK remained unchanged. In conclusion, ibuprofen inhibits tendon cell migration in a process that is probably mediated by the down-regulation of paxillin.