Statins enhance rotator cuff healing by stimulating the COX2/PGE2/EP4 pathway: an in vivo and in vitro study

A causal association between lipid-lowering medications and rotator cuff syndrome: a drug-targeted mendelian randomization study

Background: Previous research has suggested that dyslipidemia may be a risk factor for rotator cuff syndrome (RCS), and lipid-lowering drugs may aid in its treatment, though conclusions have not been definitive. Mendelian randomization is a statistical method that explores the causal relationships between exposure factors and diseases. It overcomes the confounding issues inherent in traditional observational studies, thereby providing more reliable causal inferences. We employed this method to investigate whether hyperlipidemia is a risk factor for rotator cuff syndrome and whether lipid-lowering drugs can effectively treat this condition. Methods: Genetic variations linked to lipid traits low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), and total cholesterol (TC) were acquired from the UK Biobank and the Global Lipids Genetics Consortium (GLGC). Data on genetic variation in rotator cuff syndrome were obtained from FinnGen, including 24,061 patients and 275,212 controls. In the next step, we carried out two-sample Mendelian randomization analyses to determine whether lipid traits correlate with rotator cuff syndrome risk. Additionally, we performed drug-target Mendelian randomization (MR) analyses on 10 drug targets related to rotator cuff syndrome. For the drug targets that showed significant results, further analysis was done using Summary-data-based Mendelian Randomization (SMR) and colocalization techniques. We performed a mediation analysis to identify potential mediators between HMG-CoA reductase (HMGCR) and RCS. Results: No causative link was established between these lipid traits and rotator cuff syndrome. However, a significant association has been identified where HMGCR inhibition corresponds to a reduced risk of rotator cuff disease (OR = 0.68, [95% CI, 0.56-0.83], p = 1.510 × 10-4). Additionally, enhanced expression of HMGCR in muscle tissues is also linked to a decreased risk of rotator cuff syndrome (OR = 0.88, [95% CI, 0.76-0.99], p = 0.03). Body mass index (BMI) mediated 22.97% of the total effect of HMGCR on RCS. Conclusion: This study does not support low-density LDL-C, TG, and TC as risk factors for rotator cuff syndrome. HMGCR represents a potential pharmaceutical target for preventing and treating rotator cuff syndrome. The protective action of statins on the rotator cuff syndrome might not be associated with their lipid-lowering properties.

Biomechanical comparison of suture bridge rotator cuff repair with and without dermal allograft pledgets

BACKGROUND

One method to augment rotator cuff repair is to pass dermal allograft pledgets along the sutures that bridge from the medial to the lateral row. It remains unclear whether this augmentation method alters repair biomechanics.

METHODS

This was a controlled laboratory study. After an a priori power analysis, 9 pairs of rotator cuffs underwent double-row suture bridge rotator cuff repair, half randomized to augmentation with dermal allograft pledgets passed along the suture bridge sutures. Repairs were then mounted on a material testing system and loaded cyclically 500 cycles to measure applied force and displacement. Repairs then underwent ultimate failure testing, and stiffness, ultimate failure force, and ultimate failure displacement were measured. Paired t tests were performed to compare between groups.

RESULTS

There were no differences between groups in construct gapping with cyclic loading after 500 cycles (P = .885). There were no differences between the augmented and control groups in yield force (103.5 ± 5.0 vs. 101.4 ± 5.9 N, respectively, P = .183), stiffness (94.2 ± 13.9 vs. 90.9 ± 13.8, P = .585), or ultimate failure force (255.3 ± 65.8 vs. 285.3 ± 83.2, P = .315). There were no differences between groups in failure modes, with most specimens failing by cuff tissue tearing within or medial to the construct.

CONCLUSION

The addition of dermal allograft pledgets does not positively or negatively influence the time-zero biomechanical characteristics of double-row suture bridge rotator cuff repair.

Immunomodulatory multicellular scaffolds for tendon-to-bone regeneration

Limited motor activity due to the loss of natural structure impedes recovery in patients suffering from tendon-to-bone injury. Conventional biomaterials focus on strengthening the regenerative ability of tendons/bones to restore natural structure. However, owing to ignoring the immune environment and lack of multi-tissue regenerative function, satisfactory outcomes remain elusive. Here, combined manganese silicate (MS) nanoparticles with tendon/bone-related cells, the immunomodulatory multicellular scaffolds were fabricated for integrated regeneration of tendon-to-bone. Notably, by integrating biomimetic cellular distribution and MS nanoparticles, the multicellular scaffolds exhibited diverse bioactivities. Moreover, MS nanoparticles enhanced the specific differentiation of multicellular scaffolds via regulating macrophages, which was mainly attributed to the secretion of PGE2 in macrophages induced by Mn ions. Furthermore, three animal results indicated that the scaffolds achieved immunomodulation, integrated regeneration, and function recovery at tendon-to-bone interfaces. Thus, the multicellular scaffolds based on inorganic biomaterials offer an innovative concept for immunomodulation and integrated regeneration of soft/hard tissue interfaces.

Non-steroidal Anti-inflammatory Drugs and Cyclooxygenase-2 Inhibitors Do Not Affect Healing After Rotator Cuff Repair: A Systematic Review and Meta-analysis

PURPOSE

To determine whether non-steroidal anti-inflammatory drugs (NSAIDs) and cyclooxygenase-2 (COX-2) inhibitors affect healing rate, functional outcomes, and patient satisfaction after rotator cuff repair.

METHODS

Medline, EMBASE, PsychINFO and the Cochrane Library were searched for randomized controlled trials (RCTs) investigating the use of NSAIDs and COX-2 inhibitors after arthroscopic rotator cuff repair. Primary outcomes included healing and retear rate, determined by radiological imaging. Secondary outcomes included shoulder-specific outcome measures and the visual analog scale (VAS). Risk of bias was graded using the Cochrane risk-of-bias v2.0 tool. The GRADE framework was used to assess certainty of findings.

RESULTS

Seven RCTs with a total of 507 patients were included (298 randomized to NSAID/COX-2 vs 209 randomized to control). NSAIDs use did not yield a difference in retear rate (P = .77). NSAIDs were shown to significantly reduce pain in the perioperative period (P = .01); however, no significant difference was present at a minimum of 6 months (P = .11). COX-2 inhibitors did not significantly reduce pain (P = .15). Quantitative analysis of ASES and UCLA scores showed NSAIDs significantly improved functional outcomes versus control (P = .004). COX-2 inhibitors did not significantly improve functional outcomes (P = .15). Two trials were deemed "low" risk of bias, four trials were graded to have "some concerns", and one trial was graded to have "high" risk of bias. Retear rate and functional PROMs were deemed to have "low" certainty. VAS pain scale was graded to have "moderate" certainty.

CONCLUSIONS

This systematic review and meta-analysis indicates that NSAIDs do not affect healing rate after arthroscopic rotator cuff repair, but they do significantly improve postoperative pain and functional outcomes. No significant difference was seen in pain or functional outcomes with the use of COX-2 inhibitors.

LEVEL OF EVIDENCE

Level I, meta-analysis of randomized controlled trials.

Current Research on the Influence of Statin Treatment on Rotator Cuff Healing

Rotator cuff tears are a condition characterized by damage to the muscles and tendons that connect the scapula and humerus, which are responsible for shoulder rotation and arm lifting. Metabolic factors such as diabetes, thyroid disease, high cholesterol, vitamin D deficiency, obesity, and smoking have been associated with an increased risk of rotator cuff tears. Interestingly, patients with hyperlipidemia, a condition characterized by high levels of cholesterol and other fats in the blood, have been found to have a higher incidence of rotator cuff tears and breakdown of tendon matrix. As a result, statin therapy, which is commonly used to lower cholesterol levels in hyperlipidemia, has been explored as a potential treatment to improve clinical outcomes in rotator cuff tears. However, the results of preclinical and clinical studies on the effects of statins on tendon healing in rotator cuff tears are limited and not well-defined. Moreover, since hyperlipidemia and rotator cuff tears are more prevalent in older individuals, a literature review on the efficacy and safety of statin therapy in this population is needed.

Multilayer amnion-PCL nanofibrous membrane loaded with celecoxib exerts a therapeutic effect against tendon adhesion by improving the inflammatory microenvironment

Tendon adhesion is a common complication after tendon surgery. The inflammatory phase of tendon healing is characterized by the release of a large number of inflammatory factors, whose mediated excessive inflammatory response is an important cause of tendon adhesion formation. Nonsteroidal anti-inflammatory drugs(NSAIDs) were used to prevent tendon adhesions by reducing the inflammatory response. However, recent studies have shown that the NSAIDs partially impairs tendon healing. Therefore, optimizing the anti-adhesive membrane loaded with NSAIDs to mitigate the effects on tendon healing requires further in-depth study. Amniotic membranes(AM) are natural polymeric semi-permeable membranes from living organisms that are rich in matrix, growth factors, and other active ingredients. In this study, we used electrostatic spinning technology to construct multifunctional nanofiber membranes of the PCL membrane loaded with celecoxib and AM. In vitro cellular assays revealed that celecoxib-loaded PCL membranes significantly inhibited the adhesion and proliferation of fibroblasts with increasing concentrations of celecoxib. In a rabbit tendon repair model, biomechanical tests further confirmed that the PCL membrane loaded with celecoxib had better anti-adhesion effects. Further experimental studies revealed that the PCL/AM membrane improved the inflammatory microenvironment by downregulating the expression of pro-inflammatory factors such as COX-2, IL-1β, and TNF-α proteins; and inhibiting the synthesis of COL I and COL Ⅲ. The PCL/AM membrane can continuously release celecoxib to reduce the inflammatory response and deliver growth factors to the damaged area to build a suitable microenvironment for tendon repair, which provides a new direction to improve the repair efficiency of tendon.

Progress in studying the impact of hyperlipidemia and statins on rotator cuff injury and repair

This review delves into the intersection of two prevalent conditions, hyperlipidemia and rotator cuff injuries, both of which bear substantial healthcare burdens. Our investigation begins with an exploration of rotator cuff injuries, common musculoskeletal disorders that severely impair shoulder functionality and quality of life. These injuries are notably pervasive among sports enthusiasts and the older adult, with an incidence rate estimated at 5-10% in the general population. Despite their widespread occurrence and the diverse, multifactorial etiological factors, effective treatment strategies remain elusive. We then examine hyperlipidemia, a metabolic disorder affecting approximately 40% of the global adult population. Characterized by elevated levels of cholesterol and triglycerides, hyperlipidemia can precipitate severe cardiovascular complications and presents a significant socioeconomic burden. Although current management strategies encompass lifestyle modifications and pharmacological interventions, the condition remains a formidable health challenge. Central to this review is the exploration of a potential association between hyperlipidemia and rotator cuff injuries. We aim to synthesize the current understanding of hyperlipidemia's role in the pathophysiology of rotator cuff injuries, thereby offering fresh insights into their common etiological underpinnings, potential therapeutic targets, and drugs, such as Statins. The influence of other lipid-lowering therapeutics on tendon health is also considered, and further research into the molecular pathways and potential therapeutic benefits of these drugs is required. This pursuit aligns with broader efforts to enhance patient outcomes, minimize healthcare burdens, and contribute to the global understanding of these prevalent conditions.

Non-selective NSAIDs do not increase retear rates post-arthroscopic rotator cuff repair: A meta-analysis

BACKGROUND

Arthroscopic rotator cuff repairs (RCRs) are known to be associated with substantial pain and post-operative pain management is critical in overall patients' outcomes. Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most commonly used oral medications and can reduce opioid usage. However, controversies arise due to its postulated effect on postoperative tendon healing. As the evidence of safety and efficacy of NSAIDs remains unclear, this study aims to investigate the effect of NSAIDs on retear rates and clinical outcomes.

METHODS

A systematic search of four databases (PubMed, EMBASE, Scopus, and Cochrane Library) was conducted, identifying studies that compared cohorts with post-RCR NSAIDs use versus control groups without NSAID use. Meta-analysis was conducted for retear rate as well as pain and functional outcomes (Visual Analogue Scale and American Shoulder and Elbow Surgeons Shoulder score). Subgroup analysis was conducted for retear rates to determine the overall treatment effect of including selective COX-2 inhibitors.

RESULTS

Six studies were included in the meta-analysis. The total baseline cohort size was 916, with 443 (48.3%) patients in the NSAID group and 473 (51.6%) patients in the control group. There were no statistically significant differences in the baseline characteristics between the two groups. Meta-analysis between the two groups showed that there were no statistically significant differences in retear rates (p ​= ​0.70), early and late post-operative Visual Analogue Scale score (p ​= ​0.10 and p ​= ​0.10, respectively) and latest American Shoulder and Elbow Surgeons Shoulder score (p ​= ​0.31). However, subgroup analysis of retear rates revealed a statistically significant difference between the subgroup including COX-2 selective inhibitor versus non-selective COX inhibitor (p ​< ​0.01).

CONCLUSION

NSAID use in post-arthroscopic RCR pain relief does not increase retear rates and can provide similar clinical outcomes compared to a non-NSAID regimen.

LEVEL OF EVIDENCE

Meta-analysis, level of evidence, 4.

Pharmacological Therapies for Connective Tissue Fibrosis in Orthopaedics

Fibrosis is a common and debilitating pathological process that affects many organ systems and contributes to connective tissue disorders in orthopaedics. Tendons heal after acute and chronic injury through a process of fibrovascular scar tissue formation, and soft tissue joint capsules can be affected after traumatic joint injury, leading to arthrofibrosis. Although the precise underlying mechanisms are still being elucidated, fibrosis is thought to be a consequence of dysregulated immune and cytokine signaling that leads to myofibroblast activation and proliferation and subsequent excessive collagen deposition. Current treatments for connective tissue fibrosis include physical therapy and surgery, but there are no therapies that directly target the underlying cellular and molecular mechanisms of fibrosis. Many pharmacological agents have been used to successfully target fibrosis in other tissues and organ systems and thus are a promising treatment option to fill this gap. However, limited evidence is available to guide the use of these agents in musculoskeletal connective tissues. This article provides an overview of pharmacological therapies that have potential to treat connective tissue fibrosis in patients with musculoskeletal conditions, along with the current supporting evidence and future uses of each therapy.

Relationship of Missed Statin Therapy and 10-Year Atherosclerotic Cardiovascular Disease Risk Score to Retear Rate After Arthroscopic Rotator Cuff Repair

BACKGROUND

There is no practical consensus on managing cholesterol in patients with rotator cuff repair despite hyperlipidemia and statin therapy being well-known factors in rotator cuff healing. The 10-year atherosclerotic cardiovascular disease (ASCVD) risk score is a commonly used guideline to determine statin administration for hyperlipidemia.

PURPOSE

To identify the relationship between retear and preoperative factors, including 10-year ASCVD risk score and statin administration status, and to compare clinical outcomes and retear rates between patients who are taking and not taking statins.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

This study enrolled 182 patients with a symptomatic full-thickness rotator cuff tear who underwent arthroscopic repair. Serum lipid profile, 10-year ASCVD risk score, statin eligibility, and statin administration status were assessed. Patients were categorized into 2 groups based on magnetic resonance imaging to evaluate cuff integrity at postoperative 6 months: a healed group and a retear group. Radiographic and intraoperative factors related to retear were analyzed. Multiple regression analysis was performed to evaluate factors related to rotator cuff retear. For the subgroup analysis, patients eligible for statin therapy were divided into 2 subgroups according to administration status.

RESULTS

There were 149 (81.9%) patients in the healed group and 33 (18.1%) in the retear group. In the multiple regression analysis, missed statin therapy, 10-year ASCVD risk score, and fatty infiltration of the infraspinatus muscle were the independent factors related to retear. The cutoff value for 10-year ASCVD risk score was 11.85%, with a sensitivity of 0.75 and a specificity of 0.62. In the subgroup analysis of 104 patients eligible for statin therapy, 66 (63.5%; group 1) received statin therapy and 38 (36.5%; group 2) missed it. Group 2 showed a significantly higher retear rate than group 1 (36.8% vs 13.6%; P = .006).

CONCLUSION

Missed statin therapy, 10-year ASCVD risk score, and fatty infiltration of the infraspinatus were the independent factors associated with rotator cuff retear. Patients who missed statin therapy showed a higher retear rate than patients receiving statin therapy. Optimal statin therapy for patients who undergo arthroscopic rotator cuff repair might improve repair integrity.

Dyslipidemia is associated with risk for rotator cuff repair failure: a systematic review and meta-analysis

Background

Lipid deposition secondary to dyslipidemia (DLD) is shown to have a significant impact on tendon pathology, including tendon elasticity, fatty infiltration, and healing properties. Rotator cuff repair is a common procedure, susceptible to influence from many tear-related and patient-related characteristics. The purpose of this study was to determine the relationship between DLD and rotator cuff repair outcomes with analysis of retear risk and function.

Methods

PubMed, Embase, and SPORTDiscus were searched for all English-language, peer-reviewed studies between 2000 and the present, which analyzed relationships between patient-related factors and outcomes of rotator cuff repair. Studies that explicitly examined the effect of DLD on rotator cuff repair outcomes were chosen for inclusion. Included studies were assessed for methodological quality, and data were extracted for meta-analysis.

Results

Of the 3087 titles, 424 were screened by abstract, and 67 were reviewed in full. Inclusion criteria were met by 11 studies. Of these studies, 5 studies assessed retear, 2 studies measured function, 3 studies reported both retear and function, and 1 study evaluated the risk of retear necessitating a revision surgery. The studies report no significant difference in functional outcomes. Meta-analysis revealed that DLD patients had a significantly higher risk of retear after primary rotator cuff repair (odds ratio 1.32, 95% confidence interval 1.06-1.64).

Conclusion

DLD leads to an increased risk of retear after rotator cuff repair, although function appears to be unimpaired. DLD should be considered among other risk factors when counseling patients regarding expected rotator cuff repair outcomes.

Clinical differences between patients with early and late revision surgery for symptomatic failed arthroscopic rotator cuff repair

PURPOSE

Time ranges of revision rotator cuff surgeries after arthroscopic repair are highly variable. However, the cause and clinical relevance of the different timings of revision surgeries have not been analyzed. The purpose of this study was to evaluate the clinical manifestations of patients who required revision surgeries at early and late periods after failed arthroscopic rotator cuff repair, and to identify clinical and radiological differences related to the timing of revision surgery.

METHODS

Sixty patients who underwent revision surgery due to symptomatic failed rotator cuff repair after arthroscopic repair were included. Patients were divided into two groups: patients who underwent revision surgeries within 1 year postoperatively (21 patients, group I) and patients who underwent revision surgeries more than 1 year postoperatively (39 patients, group II). Clinical and radiological characteristics were compared between the two groups before primary and revision surgery.

RESULTS

VAS for pain (5.9 ± 1.9 in group I, 3.9 ± 1.4 in group II, P < 0.001) and Constant score (50.7 ± 9.9 in group I, 60.4 ± 8.9 in group II, P < 0.001) at the time of revision surgery were significantly different between the two groups. In group II, isometric muscle strength of forward flexion (74.1 ± 21.1 to 63.9 ± 15.1, P = 0.020) and external rotation (73.0 ± 23.5 to 61.2 ± 15.0, P = 0.032) were significantly deteriorated after primary surgery, even with significant improvement of pain and shoulder function (VAS: 5.7 ± 1.9 to 3.9 ± 1.4, P < 0.001; Constant score: 50.3 ± 11.0 to 60.4 ± 8.9, P < 0.001). On postoperative MRI, re-tear at the tendon-bone interface on the greater tuberosity occurred significantly more in group I (81.0%) than group II (51.3%, P = 0.024). Incidence of full-thickness tear of the subscapularis tendon was significantly different between the two groups (42.9% in group I, 12.8% in group II, P = 0.012).

CONCLUSION

Patients who had early revision surgeries had significantly worse clinical outcomes after primary surgery than patients who had late revision surgeries. Healing failure at the tendon-bone interface on the greater tuberosity and re-tear combined with full-thickness tear of subscapularis tendon were related to early revision. Conversely, patients of the late revision group had muscle weakness that considerably impacted daily activities, even with improved pain and shoulder function.

LEVEL OF EVIDENCE

III.

Does statin-treated hyperlipidemia affect rotator cuff healing or muscle fatty infiltration after rotator cuff repair?

BACKGROUND

Hyperlipidemia is linked to poor tendon-to-bone healing and progression of fatty infiltration after rotator cuff repair. Statins effectively treat hyperlipidemia, but it is unknown if they have any potential detrimental effects following rotator cuff repair. The aim of this study was to evaluate the effect of statins on rotator cuff healing and fatty infiltration following repair.

METHODS

A total of 77 patients undergoing arthroscopic rotator cuff repair were recruited prospectively, 38 patients who were prescribed a statin for hyperlipidemia (statin group) and 39 patients who were not taking a statin (control group). Patients who did not have both preoperative and 1-year postoperative magnetic resonance imaging (MRI) scans were excluded from the study. Patient-reported outcome measures, namely the Western Ontario Rotator Cuff (WORC) index, Constant-Murley score, American Shoulder and Elbow Surgeons (ASES) score, and Disabilities of the Arm, Shoulder and Hand (DASH) score, were collected preoperatively and at 1 year. Fatty infiltration was assessed on MRI according to the Goutallier grade preoperatively and at 12 months; rotator cuff healing was assessed at 12 months according to the Sugaya classification. Following propensity score weighting to adjust for baseline imbalances, 12-month outcomes were compared between the 2 groups.

RESULTS

At 12 months, all patient-reported outcome measures had improved significantly compared with baseline (WORC score, 85.9 vs. 32.5, P < .001; ASES score, 87.3 vs. 37.5, P < .001; Constant-Murley score, 77 vs. 31, P < .001; and DASH score, 13.6 vs. 61.4, P < .001). There was no significant difference in postoperative scores in the statin group vs. the control group (WORC score, 84.9 vs. 89.6, P = .94; ASES score, 87.5 vs. 86.6, P = .40; Constant-Murley score, 77 vs. 81, P = .90; and DASH score, 14.4 vs. 11.4, P = .14), and for 3 of these scores, the 95% confidence intervals excluded a clinically meaningful difference. Similarly, rotator cuff healing at 12 months and Goutallier fatty infiltration grades were comparable between the 2 groups. Retears were seen in 6 patients (15.8%) in the statin group and 8 (20.5%) in the control group. Progression of fatty infiltration was seen in 4 patients (10.5%) in the statin and 4 (10.3%) in the control group. Statin use did not demonstrate a significant association with either retear risk (P = .41) or progression of fatty atrophy (P = .69).

CONCLUSION

Patient-reported outcomes, rotator cuff retear rate, and fatty infiltration on MRI at 12 months after rotator cuff repair in patients with hyperlipidemia treated with statins are similar to those in a control group.

LncRNA XIST Prevents Tendon Adhesion and Promotes Tendon Repair Through the miR-26a-5p/COX2 Pathway

Tendon adhesion is the biggest obstacle to repair of tendon injury. Long-chain non-coding RNA X-inactive specific transcript (lncRNA XIST) is highly expressed in populations at high risk of tendon injury. However, whether XIST participates in tendon injury and the specific mechanism remain unknown. Here, we aimed to explore the effects and underlying mechanism of XIST in tendon injury. A mouse model of tendon injury was constructed by the transection method in vivo. XIST and COX2 were highly expressed in tendon tissues of mice with tendon injury, while miR-26a-5p was lowly expressed. Fibroblasts were isolated from tendon injury mice. Overexpression of XIST promoted fibroblast proliferation and upregulated α-SMA and Collagen I protein expression, while silencing XIST indicated the opposite effects. Further dual-luciferase reporter gene assay and RIP assay verified a targeting relationship between XIST and miR-26a-5p, as well as miR-26a-5p and COX2, and XIST targeted miR-26a-5p to act on COX2 expression. miR-26a-5p inhibition and COX2 overexpression reversed the decrease in fibroblast proliferation and the downregulation of α-SMA and Collagen I expression caused by XIST silencing, while interference with si-COX2 eliminated the effects of miR-26a-5p inhibitor. This study revealed that XIST promoted fibroblast proliferation and the formation of tendon adhesion through miR-26a-5p/COX2 pathway, suggesting that XIST/miR-26a-5p/COX2 may be a potential target for the treatment of tendon injury.

Role of prostaglandin E2 in tissue repair and regeneration

Tissue regeneration following injury from disease or medical treatment still represents a challenge in regeneration medicine. Prostaglandin E2 (PGE2), which involves diverse physiological processes via E-type prostanoid (EP) receptor family, favors the regeneration of various organ systems following injury for its capabilities such as activation of endogenous stem cells, immune regulation, and angiogenesis. Understanding how PGE2 modulates tissue regeneration and then exploring how to elevate the regenerative efficiency of PGE2 will provide key insights into the tissue repair and regeneration processes by PGE2. In this review, we summarized the application of PGE2 to guide the regeneration of different tissues, including skin, heart, liver, kidney, intestine, bone, skeletal muscle, and hematopoietic stem cell regeneration. Moreover, we introduced PGE2-based therapeutic strategies to accelerate the recovery of impaired tissue or organs, including 15-hydroxyprostaglandin dehydrogenase (15-PGDH) inhibitors boosting endogenous PGE2 levels and biomaterial scaffolds to control PGE2 release.

NSAIDs inhibit bone healing through the downregulation of TGF-β3 expression during endochondral ossification

INTRODUCTION & AIMS

Non Steroidal Anti-Inflammatory drugs (NSAIDs) are potent inhibitors of post-traumatic pain. Several studies have highlighted that NSAIDs could exert a negative effect on bone healing process possibly by down-regulating chondrogenesis and endochondral ossification. The aim of the study is to explore the potential mechanism though which NSAIDs can affect chondrogenesis. M&M: Trabecular bone from the fracture site was isolated from 10 patients suffering from long bone fractures. Mesenchymal Stem Cells (MSCs) were isolated following collagenase digestion and functional assays to assess the effect of diclofenac sodium on chondrogenesis were performed. Gene expression analysis of 84 key molecules was performed.

RESULTS

Diclofenac sodium inhibits chondrogenic differentiation and induces a strong inhibition of prostaglandin E-2 (PGE-2) production during chondrogenic differentiation. Replenishment of PGE-2 did not reverse this negative effect. Chondrogenic inhibition is similar in cells treated only for the first week of chondrogenic differentiation or continuously for 3 weeks. Gene analysis shows a strong downregulation of TGF-β3 and FGF-1 while TNF was upregulated.

CONCLUSION

NSAIDs seem to affect the transition phase of mesenchymal stem cells towards functional chondrocytes. This effect is unrelated to the endogenous production of PGE-2. The downregulation of the expression of key molecules like TGF-β3 seem to be the underlying mechanism.

Celecoxib-Loaded Electrospun Fibrous Antiadhesion Membranes Reduce COX-2/PGE2 Induced Inflammation and Epidural Fibrosis in a Rat Failed Back Surgery Syndrome Model

To date, failed back surgery syndrome (FBSS) remains a therapy-refractory clinical condition after spinal surgery. The antiadhesion membrane is applied to prevent FBSS by isolating fibrosis; however, the inflammation stimulated by the foreign body and surgical trauma needs to be further resolved simultaneously. Therefore, we developed new electrospun polycaprolactone (PCL) fibrous membranes loaded with celecoxib (CEL) to prevent fibrosis and inflammation associated with FBSS. The CEL-loaded PCL fibers were randomly distributed, and the drug was released over two weeks. Fluorescence micrographs revealed that the fibroblasts proliferated less on the PCL-CEL fibrous membranes than in the PCL group and the blank control. In the rat laminectomy model after 4 weeks, magnetic resonance imaging of epidural fibrosis was least in the PCL-CEL group. Expression of COX-2 and PGE2 was lower in the PCL-CEL group. It concluded that the CEL-loaded PCL membrane could reduce fibrosis and inflammation in a rat model of FBSS via COX-2/PGE2 signaling pathways.

Polymorphisms and alterations in gene expression associated with rotator cuff tear and healing following surgical repair: a systematic review

BACKGROUND

Rotator cuff tears (RCTs) are a common cause of shoulder disability, yet both conservative and surgical treatment strategies can lead to poor results in some patient populations. Enhanced understanding of the genetic processes associated with RCTs can assist in the development of more effective management options and help predict individual responses to surgical treatment. This systematic review analyzes the current literature on the genetic footprint associated with RCTs and interprets these findings to enhance the current understanding of RCT pathogenesis, potential treatment regimens, and prognostic biomarkers of outcomes after surgical repair.

METHODS

A systematic search of the Embase, PubMed, and Web of Science electronic databases was performed. Medical Subject Headings (MeSH) and Emtree index terms were formulated from the concept terms "rotator cuff tear," "genetics," and "human," and synonyms of these concepts were applied to the Web of Science search. Articles were screened against predefined inclusion and exclusion criteria. Eligible studies compared gene expression patterns and genetic polymorphisms between cases (with RCTs) and controls (without RCTs). Quality assessment was performed with studies being rated as high, moderate, or poor quality. A modified best-evidence synthesis was applied, and studies were determined to be of strong, moderate, or limited evidence.

RESULTS

The search identified 259 articles. Of these studies, 26 were eligible for review. Two studies were considered poor quality; 15 studies, moderate quality; and 9 studies, high quality. Analysis of these articles found that RCTs were associated with alterations in genes that code for the extracellular matrix, cell apoptosis, immune and inflammatory responses, and growth factor pathways. In particular, there was strong evidence of a significant association between RCTs and the genes MMP3, TNC, and ESRRB. Strong evidence of an association between BMP5 upregulation and successful healing after surgical repair was also found.

CONCLUSION

This review provides strong evidence of an genetic association with RCTs. The genotype and gene expression patterns detailed within this review can assist in deciphering the biological mechanisms resulting in RCTs, as well as predicting an individual's response to surgical repair. Future research could investigate whether manipulating these genes-or their associated signaling pathways-could assist in RCT healing and whether genetic biomarkers could be used clinically to predict patient outcomes after surgical repair of RCTs.

Healing rates after rotator cuff repair for patients taking either celecoxib or placebo: a double-blind randomized controlled trial

Background

Use of anti-inflammatory medications (NSAIDs) is an important component of multimodal pain control after orthopedic procedures to avoid opioid overutilization and abuse. However, the deleterious effects of NSAIDs on tendon healing are of particular concern in rotator cuff repair (RCR). The purpose of this study was to evaluate the effect of celecoxib or placebo on healing rates after RCR when administered in the perioperative and immediate postoperative period using MRI evaluation at one year postoperatively. A secondary aim was to determine whether clinical differences existed between patients with intact or non-intact repairs.

Methods

Patients aged ≤65 years with partial- or full-thickness rotator cuff tear (<25x25 mm) were randomized to receive celecoxib 400 mg or placebo 1 hour before the procedure and 200mg bid for 3 weeks postoperatively. All patients were treated as clinically indicated at the time of surgery and followed standard postoperative protocol. Repair integrity was evaluated with MRI using the Sugaya classification for repair integrity. Data were analyzed using multivariable logistic regression by intent to treat.

Results

Seventy-nine patients were enrolled; 21 were lost to follow-up, 6 did not have cuff repair, 5 were revised, and 2 declined follow-up, leaving 45 patients with one-year follow-up. Five of these patients did not complete MRI, leaving 40 patients for review. Eighteen of 20 patients (90%) who received celecoxib completed all doses of study medication as did 15 of 20 patients (75%) who received placebo. The patient groups were similar for demographics, clinical results, and healing rate. After adjusting for tear size, no statistically significant difference in healing rate was found between groups, with 10 of 20 celecoxib patients (50%) having intact repair at 1 year compared with 14 of 20 placebo patients (70%) (OR = 0.53, 95% CI: 0.14, 2.08, P = 0.35).

Conclusion

Half of the patients who received celecoxib had an intact repair compared with 70% intact repair for patients receiving placebo. Although not statistically significant in this small study, larger studies are needed to clarify this important clinical concern. The authors do not recommend use of celecoxib for postoperative pain control after RCR.

Spectrum of Tendon Pathologies: Triggers, Trails and End-State

The biggest compartment of the musculoskeletal system is the tendons and ligaments. In particular, tendons are dense tissues connecting muscle to bone that are critical for the integrity, function and locomotion of this system. Due to the increasing age of our society and the overall rise in engagement in extreme and overuse sports, there is a growing prevalence of tendinopathies. Despite the recent advances in tendon research and due to difficult early diagnosis, a multitude of risk factors and vague understanding of the underlying biological mechanisms involved in the progression of tendon injuries, the toolbox of treatment strategies remains limited and non-satisfactory. This review is designed to summarize the current knowledge of triggers, trails and end state of tendinopathies.

Double-row rotator cuff repairs lead to more intensive pain during the early postoperative period but have a lower risk of residual pain than single-row repairs

PURPOSE

The purpose of this study is to compare pain patterns and identify factors associated with residual shoulder pain after rotator cuff repairs using double-row and single-row techniques.

METHODS

A cohort study was performed using patients who underwent arthroscopic rotator cuff repairs at our center in 2015. Patients were allocated according to the repair technique into an single-row (SR) group or a double-row (DR) group. Visual Analog Scale (VAS) scores for pain were assessed at 1 week, 3 months, 6 months, 12 months and 24 months after surgery. Functional and radiographic assessments were performed at least 24 months postoperatively. The proportion of patients with residual pain and factors associated with residual shoulder pain (VAS > 0 at the final follow-up) were analyzed in both groups.

RESULTS

Fifty-two patients were enrolled in the SR group, and 53 were enrolled in the DR group. The DR group appeared to have higher levels of pain 1 week (P < 0.001) and 3 months (P = 0.041) postoperatively, while at other time points, the pain intensity of the two groups was comparable. Fourteen (26.4%) and 25 (48.1%) patients in the DR and the SR groups, respectively, developed residual shoulder pain, (P = 0.022; RR 1.82). The univariate analysis and multiple regression revealed that a poorer quality of tendon tissue is related to residual pain in the SR group, whereas tendon retraction is associated with residual pain in the DR group. The rate of re-tear was similar between the two groups and between patients with and without residual pain.

CONCLUSIONS

The DR repair technique results in a greater intensity of pain than that of SR repair during the first 3 months after surgery; however, patients who underwent DR repair presented a significantly lower proportion of residual shoulder pain and better tendon quality after 2 years. Poorer tendon quality and larger tendon retraction as determined intraoperatively were risk factors for residual pain. These results highlight the necessity of promoting healing on the grounds of residual pain prevention.

LEVEL OF EVIDENCE

II.

Post-operative non-steroidal anti-inflammatory drugs do not affect clinical outcomes of rotator cuff repair

Background

The administration of non-steroidal anti-inflammatory drugs (NSAIDs) to patients is thought to impair rotator cuff healing and clinical outcomes.

Methods

36 patients who underwent rotator cuff repair were divided into 3 groups based on their post-operative analgesia regimes.

Results

At 4.4 years postoperative, there was significant improvement in SST and UCLA scores (p < 0.001). There were no significant differences in post-operative clinical outcome scores between the groups (p > 0.05). Administration of NSAIDs and duration of their use did not influence outcomes of rotator cuff repair (p = 0.151).

Conclusion

NSAIDs has no significant influence on clinical outcomes of rotator cuff repair.

Real-Time Monitoring of Ascorbic Acid-Mediated Reduction of Cytotoxic Effects of Analgesics and NSAIDs on Tenocytes Proliferation

Tendinopathy is a common painful musculoskeletal disorder treated by injection of analgesics and nonsteroidal anti-inflammatory drugs (NSAIDs), which are believed to have cytotoxicity toward tenocytes. Ascorbic acid is an antioxidant that promotes collagen biosynthesis and prevents free radical formation. It is believed to protect tenocytes from oxidative stress. The optimal concentration of ascorbic acid, especially when used in conjunction with anesthetics and NSAIDs injection, to treat different stages of tendinopathies is unknown. Human tenocytes were isolated from a torn edge of the supraspinatus tendon of a 51-year-old male patient during arthroscopic repair. We monitored real-time changes in human tenocyte proliferation upon exposure to different concentrations of ascorbic acid, bupivacaine, and ketorolac tromethamine using the xCELLigence system. No significant changes in cell index were observed between the control group and tenocytes treated with the 3 concentrations of ascorbic acid. Tenocytes exposed to 0.5% bupivacaine and 30 or 15 mg/mL ketorolac tromethamine revealed significant reduction in tenocytes proliferation. Bupivacaine 0.5% with 250 μg/mL ascorbic acid and 15 mg/mL ketorolac tromethamine with 250 μg/mL ascorbic acid showed the least cytotoxicity against tenocytes. The optimal ascorbic acid concentration required to reduce the cytotoxic effects of bupivacaine and ketorolac tromethamine was demonstrated using this platform.

Effect of Suture Absorbability on Rotator Cuff Healing in a Rabbit Rotator Cuff Repair Model

BACKGROUND

Various suture materials can be clinically used for rotator cuff repair (RCR). RCR with high-strength nonabsorbable sutures may not be ideal, because it may cause stress shielding, which may hinder enthesis regeneration and maturation in the tendon-bone interface. RCR with strength-decreasing sutures (ie, absorbable sutures) may be a better choice. However, the effects of suture absorbability on enthesis regeneration and maturation have not been investigated.

HYPOTHESIS

The use of absorbable sutures in RCR would produce a better tendon-bone connection structure, which provides histological and biomechanical advantages over the use of nonabsorbable sutures.

STUDY DESIGN

Controlled laboratory study.

METHODS

A supraspinatus tear was created on the right shoulder in 108 of 120 skeletally mature male rabbits. The animals were randomly divided into 3 groups, with 36 rabbits in each group, to undergo RCR individually with total absorbable, partial absorbable, and nonabsorbable sutures (TAS, PAS, and NAS). Twelve animals in each group were sacrificed at 4, 8, and 12 weeks after surgery, with 6 operated shoulders used for histological evaluation to detect enthesis regeneration and maturation and the other 6 for biomechanical testing. The remaining 12 animals without supraspinatus tear were used as control.

RESULTS

At 12 weeks, in the tendon-bone interface, enthesis regeneration was detected in the TAS group but not in the NAS group. A mature enthesis appeared in the TAS group but not in the NAS group. In the PAS group, enthesis regeneration was also observed; however, the fibrocartilage was not abundant and the enthesis maturity not good as compared with the TAS group. Biomechanical testing showed that the rotator cuff-greater tuberosity connection structure in the TAS and PAS groups had greater values of ultimate load to failure, stiffness, and stress than the NAS group at all time points.

CONCLUSION

In RCR in an acute rabbit rotator cuff tear model, the use of sutures with absorbability lead to enthesis regeneration, increased maturity of rotator cuff insertion, and enhanced rotator cuff-greater tuberosity connection.

CLINICAL RELEVANCE

Compared with the use of NAS, the use of TAS or PAS might be a better choice for RCR.

The effects of hyperlipidemia on rotator cuff diseases: a systematic review

BACKGROUND

Rotator cuff disease is a common condition that causes shoulder pain and functional disability. Recent studies suggested that hyperlipidemia might be associated with the development of rotator cuff disease. The objective of this study was to explore the relationship of hyperlipidemia and rotator cuff diseases.

METHODS

A computerized search using relevant search terms was performed in the PubMed, EMBASE, and Cochrane Library databases, as well as a manual search of reference and citation lists of the included studies. Searches were limited to studies that explored the association of hyperlipidemia and rotator cuff diseases.

RESULTS

Sixteen studies were included in this systematic review. Ten of sixteen included studies suggested an association between dyslipidemia and rotator cuff diseases, while the other six studies did not find an association. Two studies demonstrated there were an association between statins and reduced risk of developing rotator cuff diseases or decreased incidence of revision after rotator cuff repair.

CONCLUSION

The current study suggested that there was an association between hyperlipidemia and rotator cuff diseases. Furthermore, current evidence suggested that use of statins could decrease the risk of developing rotator cuff diseases and the incidence of revision after rotator cuff repair. Future high-quality studies are highly needed to confirm these findings.

Biologics and stem cell-based therapies for rotator cuff repair

The rotator cuff is composed of several distinct muscles and tendons that function in concert to coordinate shoulder motion. Injuries to these tendons frequently result in permanent dysfunction and persistent pain. Despite considerable advances in operation techniques, surgical repair alone still does not fully restore rotator cuff function. This review focuses on recent research in the use of biologics and stem cell-based therapies to augment repair, highlighting promising avenues for future work and remaining challenges. While a number of animal models are used for rotator cuff studies, the anatomy of the rotator cuff varies dramatically between species. Since the rodent rotator cuff shares the most anatomical features with the human, this review will focus primarily on rodent models to enable consistent interpretation of outcome measures.

Aspirin alone and combined with a statin suppresses eicosanoid formation in human colon tissue

Eicosanoids, including prostaglandins (PGs) and thromboxanes, are broadly bioactive lipid mediators and increase colon tumorigenesis possibly through chronic inflammatory mechanisms. Epidemiological and experimental data suggest that acetylsalicylic acid (ASA) helps prevent colorectal cancer (CRC), possibly through cyclooxygenase (COX)-mediated suppression of eicosanoid, particularly PGE2, formation. Recent studies suggest that statins prevent CRC and improve survival after diagnosis. We identified patients on ASA and/or statin treatment undergoing routine colonoscopy and measured eicosanoid levels in colonic mucosa with targeted metabolomics technology (LC-MS/MS). ASA-treated individuals (n = 27) had significantly lower tissue eicosanoid levels of most COX-derived metabolites than untreated individuals (n = 31). In contrast, COX-derived lipid metabolites tended to be higher in patients with statin treatment (n = 7) as compared with those not receiving statins (n = 24). This effect was not discernible in subjects treated with ASA and statins (n = 11): Individuals treated with both drugs showed a pronounced suppression of COX-derived eicosanoids in colon tissue, even compared with subjects treated with ASA alone. Our data from a routine clinical setting support the hypothesis that ASA and statins could inhibit CRC development via lipid mediator modification. Further studies should directly investigate the effect of dual ASA and statin treatment on colon tumorigenesis in humans.

Exploring the In Vivo Anti-Inflammatory Actions of Simvastatin-Loaded Porous Microspheres on Inflamed Tenocytes in a Collagenase-Induced Animal Model of Achilles Tendinitis

Tendon rupture induces an inflammatory response characterized by release of pro-inflammatory cytokines and impaired tendon performance. This study sought to investigate the therapeutic effects of simvastatin-loaded porous microspheres (SIM/PMSs) on inflamed tenocytes in vitro and collagenase-induced Achilles tendinitis in vivo. The treatment of SIM/PMSs in lipopolysaccharide (LPS)-treated tenocytes reduced the mRNA expressions of pro-inflammatory cytokines (Matrix metalloproteinase-3 (MMP-3), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α)). In addition, the local injection of SIM/PMSs into the tendons of collagenase-induced Achilles tendinitis rat models suppressed pro-inflammatory cytokines (MMP-3, COX-2, IL-6, TNF-α, and MMP-13). This local treatment also upregulated anti-inflammatory cytokines (IL-4, IL-10, and IL-13). Furthermore, treatment with SIM/PMSs also improved the alignment of collagen fibrils and effectively prevented collagen disruption in a dose-dependent manner. Therefore, SIM/PMSs treatment resulted in an incremental increase in the collagen content, stiffness, and tensile strength in tendons. This study suggests that SIM/PMSs have great potential for tendon healing and restoration in Achilles tendinitis.

Do Selective COX-2 Inhibitors Affect Pain Control and Healing After Arthroscopic Rotator Cuff Repair? A Preliminary Study

BACKGROUND

Selective cyclooxygenase (COX)-2 inhibitors are commonly used analgesics that provide similar analgesia as that of other analgesics but with fewer adverse effects. However, few prospective studies have performed comparative analyses in this regard.

PURPOSE

To evaluate the efficacy of a selective COX-2 inhibitor in early postoperative pain control, satisfaction with pain management, and incidence of systemic adverse effects in patients undergoing arthroscopic rotator cuff repair.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

This study included 180 patients who underwent arthroscopic rotator cuff repair between September 2011 and August 2012. The patients were randomly assigned to receive celecoxib, ibuprofen, or tramadol (n = 60 each). Visual analog scale (VAS) scores for pain intensity and satisfaction with medication, incidence of adverse effects, and use of rescue medication were recorded and compared between the 3 groups at 3 days and 2 weeks after surgery. Magnetic resonance and ultrasonography images of 82 patients were retrospectively reviewed at least 24 months after surgery, along with the range of motion and pain VAS and functional scores.

RESULTS

There were no significant differences among the 3 groups in terms of pain intensity, incidence of adverse effects, or dosage of rescue medication at 3 days or 2 weeks after surgery. Pain VAS and functional scores at the final follow-up were also comparable among the 3 groups. However, the retear rate in the celecoxib group (11/30 [37%]) was significantly higher than those in the ibuprofen (2/27 [7%]) and tramadol (1/25 [4%]) groups ( P = .009).

CONCLUSION

Despite having similar postoperative analgesic effects as other nonsteroidal anti-inflammatory drugs and opioids, selective COX-2 inhibitors should not be used for postoperative analgesia because they might negatively affect tendon-to-bone healing after surgical repair. Registration: NCT02850211 ( ClinicalTrials.gov identifier).

Ibuprofen impairs capsulolabral healing in a rat model of anterior glenohumeral instability

BACKGROUND

Failure of glenoid labrum and capsular healing after glenohumeral dislocation can lead to persistent shoulder instability. The purpose of this study was to determine the effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on the healing glenoid labrum and capsule after glenohumeral dislocation in a rat model.

METHODS

Sixty-six rats had surgically induced anterior-inferior labral tears and anterior glenohumeral dislocation. Postoperatively, the animals were assigned to either normal (n = 32) or ibuprofen drinking water (n = 31). Animals were euthanized at 2 and 4 weeks postoperatively for biomechanical testing and histologic analysis.

RESULTS

The maximum load increased from 2 to 4 weeks after injury in the NSAID groups but not in the control groups. At 2 weeks, the maximum load was lower in the NSAID group compared with the control group. In a matched comparison between injured and uninjured limbs, the maximum load was significantly decreased in the injured limb of the 2-week NSAID group. At 4 weeks, the NSAID group had decreased stiffness compared with the 4-week control group.

CONCLUSIONS

In a new rat model of glenohumeral instability, the postinjury administration of ibuprofen resulted in decreased capsulolabral healing. A matched pair analysis of injured to uninjured limbs supported the findings of impaired healing in the NSAID-treated animals. These findings demonstrate that the use of NSAIDs after glenohumeral dislocation may impair capsulolabral healing and should be limited or avoided to optimize glenohumeral stability.

Perioperative Serum Lipid Status and Statin Use Affect the Revision Surgery Rate After Arthroscopic Rotator Cuff Repair

BACKGROUND

Recent animal studies have demonstrated that hyperlipidemia is associated with poor tendon-bone healing after rotator cuff repair; however, these findings have not been substantiated in human studies.

PURPOSE

To examine any association between hyperlipidemia and the failure of arthroscopic rotator cuff repair requiring revision surgery and to investigate whether the use of statin lipid-lowering agents had any influence on observed associations.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

From a national insurance database, patients who underwent arthroscopic rotator cuff repair with perioperative lipid levels (total cholesterol, low-density lipoprotein [LDL], and triglycerides) recorded were reviewed. For each lipid test, patients were stratified into normal, moderate, and high groups based on published standards. For the total cholesterol and LDL cohorts, a subgroup analysis of patients stratified by statin use was performed. The primary outcome measure was ipsilateral revision rotator cuff surgery, including revision repair or debridement. A logistic regression analysis controlling for patient demographics and comorbidities was utilized for comparison.

RESULTS

There were 30,638 patients included in the study. The rate of revision rotator cuff surgery was significantly increased in patients with moderate (odds ratio [OR], 1.20; 95% CI, 1.03-1.40; P = .022) and high total cholesterol levels (OR, 1.36; 95% CI, 1.10-1.55; P = .006) compared with patients with normal total cholesterol levels perioperatively. Within each of these groups, patients without statin use had significantly higher rates of revision surgery, while those with statin prescriptions did not. The absolute risk reduction for statin use ranged from 0.24% to 1.87% when stratified by the total cholesterol level, yielding a number needed to treat from 54 to 408 patients. The rate of revision surgery was significantly increased in patients with moderate (OR, 1.24; 95% CI, 1.10-1.41; P = .001) and high LDL levels (OR, 1.46; 95% CI, 1.08-1.99; P = .014) compared with patients with normal LDL levels perioperatively. Again, patients without statin prescriptions had significantly increased rates of revision surgery, whereas patients with statin use did not. The absolute risk reduction for statin use ranged from 0.26% to 1.89% when stratified by the LDL level, yielding a number needed to treat from 53 to 387 patients. There were no significant differences in the rates of revision rotator cuff surgery between patients with moderate and high triglyceride levels compared with patients with normal triglyceride levels.

CONCLUSION

The present study found a significant association between moderate and high perioperative total cholesterol and LDL levels and the rate of revision surgery after primary arthroscopic rotator cuff repair. Furthermore, the use of statin agents appeared to mitigate the need for revision rotator cuff repair. Further prospective studies are necessary to validate these preliminary findings and determine if better perioperative lipid control can improve clinical outcomes after arthroscopic rotator cuff repair.

Comparison between xCELLigence biosensor technology and conventional cell culture system for real-time monitoring human tenocytes proliferation and drugs cytotoxicity screening

Background

Local injections of anesthetics, NSAIDs, and corticosteroids for tendinopathies are empirically used. They are believed to have some cytotoxicity toward tenocytes. The maximal efficacy dosages of local injections should be determined. A commercial 2D microfluidic xCELLigence system had been developed to detect real-time cellular proliferation and their responses to different stimuli and had been used in several biomedical applications. The purpose of this study is to determine if human tenocytes can successfully proliferate inside xCELLigence system and the result has high correlation with conventional cell culture methods in the same condition.

Methods

First passage of human tenocytes was seeded in xCELLigence and conventional 24-well plates. Ketorolac tromethamine, bupivacaine, methylprednisolone, and betamethasone with different concentrations (100, 50, and 10% diluted of clinical usage) were exposed in both systems. Gene expression of type I collagen, type III collagen, tenascin-C, decorin, and scleraxis were compared between two systems.

Results

Human tenocytes could proliferate both in xCELLigence and conventional cell culture systems. Cytotoxicity of each drug revealed dose-dependency when exposed to tenocytes in both systems. Significance was found between groups. All the four drugs had comparable cytotoxicity in their 100% concentration. When 50% concentration was used, betamethasone had a relatively decreased cytotoxicity among them in xCELLigence but not in conventional culture. When 10% concentration was used, betamethasone had the least cytotoxicity. Strong and positive correlation was found between cell index of xCELLigence and result of WST-1 assay (Pearson’s correlation [r] = 0.914). Positive correlation of gene expression between tenocytes in xCELLigence and conventional culture was also observed. Type I collagen: [r] = 0.823; type III collagen: [r] = 0.899; tenascin-C: [r] = 0.917; decorin: [r] = 0.874; and scleraxis: [r] = 0.965.

Conclusions

Human tenocytes could proliferate inside xCELLigence system. These responses varied when tenocytes were exposed to different concentrations of ketorolac tromethamine, bupivacaine, methylprednisolone, and betamethasone. The result of cell proliferation and gene expression of tenocytes in both xCELLigence and conventional culture system is strongly correlated.

Clinical relevance

xCELLigence culture system may replace conventional cell culture, which made real-time tenocyte proliferation monitoring possible.

What is the role of systemic conditions and options for manipulation of bone formation and bone resorption in rotator cuff tendon healing and repair?

Rotator cuff pathology is a significant cause of shoulder pain. Operative repair of rotator cuff is an established standard of care for these patient, however, failure of the procedure is common. Systemic conditions such as diabetes mellitus, hypocholesteremia, thyroid disease, and smoking significantly affect the outcomes of rotator cuff repair and have significant implications for the management of these patients. Diabetes mellitus has been proposed to damage tendons through non-enzymatic glycosylation of collagen with advanced glycation end product formation and impaired microcirculation. Hypocholesteremia may lead to fatty infiltration and subsequent pro-inflammatory degenerative enzymatic degeneration. Thyroid disease may disrupt tendon homeostasis through the alteration of collagen production and the accumulation of glycosaminoglycans. Lastly, smoking inhibits tendon healing through the induction of hypovascularity and hypoperfusion. Understanding of the implications these systemic conditions have on the outcomes is important in the management of rotator cuff disease.

Peroxisome proliferator‑activated receptor γ mediates porcine placental angiogenesis through hypoxia inducible factor‑, vascular endothelial growth factor‑ and angiopoietin‑mediated signaling

Peroxisome proliferator-activated receptor (PPAR) γ has been reported to be implicated in placentation in mice. Previous studies have demonstrated that PPARγ is also expressed in porcine placenta, primarily localized in vascular endothelial cells (VECs). The present study aimed to investigate the roles of PPARγ during porcine placental angiogenesis and examine the molecular mechanisms involved in its actions. VECs were incubated with the PPARγ agonist rosiglitazone and the antagonist T0070907, and their angiogenic potential was evaluated using cellular impedance, wound healing and tube formation assays. Reverse transcription-quantitative polymerase chain reaction was used to assess the mRNA expression levels of angiogenic factors, including hypoxia-inducible factors (HIFs), vascular endothelial growth factor (VEGF) isoforms, VEGF receptors (VEGFRs) and angiopoietins (Angs). The results demonstrated that the adhesive, proliferative and migratory capabilities of VECs were potentiated by rosiglitazone and suppressed by T0070907. Notably, tube formation was invariably promoted during PPARγ activation and blockade. The mRNA expression levels of HIF1α, HIF2α, VEGFR2, VEGF188 and Ang-1 were revealed to be upregulated following treatment of VECs with rosiglitazone, whereas they were downregulated following treatment with T0070907. However, the mRNA expression levels of placental growth factor and VEGF120 were consistently downregulated following PPARγ activation and blockade, whereas VEGF164 mRNA levels remained unaltered. The results of the present study suggested that PPARγ may mediate porcine placental angiogenesis, by interfering with HIF-, VEGF- and angiopoietin-mediated signaling pathways.

Statin-induced calcific Achilles tendinopathy in rats: comparison of biomechanical and histopathological effects of simvastatin, atorvastatin and rosuvastatin

PURPOSE

Accumulating clinical evidence indicates the risk of tendinopathy and spontaneous and/or simultaneous tendon ruptures associated with statin use. This experimental study was designed to evaluate and compare the biomechanical and histopathological effects of the three most commonly prescribed statins (simvastatin, atorvastatin and rosuvastatin) on the Achilles tendon in rats.

METHODS

Statins were administered by gavage to rats at daily doses of 20 and 40 mg/kg for 3 weeks. One week later, the Achilles tendons were dissected and their biomechanical properties, including ultimate tensile force, yield force and elastic modulus, were determined. The samples were stained with haematoxylin-eosin and examined under a light microscope. The biomechanical properties of the tibia were tested by three-point bending test. Bone mineral density (BMD) and the lengths of tibias were measured by computed tomography.

RESULTS

All the statins caused deterioration of the biomechanical parameters of the Achilles tendon. Histopathological analysis demonstrated foci of dystrophic calcification only in the statin-treated groups. However, the number and the total area of calcific deposits were similar between the statin groups. The biomechanical parameters of tibias were improved in all the statin groups. BMD in the statin-treated groups was not significantly different from the control group.

CONCLUSION

All the statins tested are associated with calcific tendinopathy risk of which full awareness is required during everyday medical practice. However, statin-associated improvement of bone biomechanical properties is a favourable feature which may add to their beneficial effects in atherosclerotic cardiovascular disease, especially in the elderly.

Statins Reduce Lipopolysaccharide-Induced Cytokine and Inflammatory Mediator Release in an In Vitro Model of Microglial-Like Cells

The anti-inflammatory effects of statins (HMG-CoA reductase inhibitors) within the cardiovascular system are well-established; however, their neuroinflammatory potential is unclear. It is currently unknown whether statins' neurological effects are lipid-dependent or due to pleiotropic mechanisms. Therefore, the assumption that all statin compounds will have the same effect within the central nervous system is potentially inappropriate, with no studies to date having compared all statins in a single model. Thus, the aim of this study was to compare the effects of the six statins (atorvastatin, fluvastatin, pitavastatin, pravastatin, rosuvastatin, and simvastatin) within a single in vitro model of neuroinflammation. To achieve this, PMA-differentiated THP-1 cells were used as surrogate microglial cells, and LPS was used to induce inflammatory conditions. Here, we show that pretreatment with all statins was able to significantly reduce LPS-induced interleukin (IL)-1β and tumour necrosis factor (TNF)-α release, as well as decrease LPS-induced prostaglandin E2 (PGE2). Similarly, global reactive oxygen species (ROS) and nitric oxide (NO) production were decreased following pretreatment with all statins. Based on these findings, it is suggested that more complex cellular models should be considered to further compare individual statin compounds, including translation into in vivo models of acute and/or chronic neuroinflammation.

Simvastatin and atorvastatin reduce the mechanical properties of tendon constructs in vitro and introduce catabolic changes in the gene expression pattern

Treatment with lipid-lowering drugs, statins, is common all over the world. Lately, the occurrence of spontaneous tendon ruptures or tendinosis have suggested a negative influence of statins upon tendon tissue. But how statins might influence tendons is not clear. In the present study, we investigated the effect of statin treatment on mechanical strength, cell proliferation, collagen content and gene expression pattern in a tendon-like tissue made from human tenocytes in vitro. Human tendon fibroblasts were grown in a 3D tissue culture model (tendon constructs), and treated with either simvastatin or atorvastatin, low or high dose, respectively, for up to seven days. After seven days of treatment, mechanical testing of the constructs was performed. Collagen content and cell proliferation were also determined. mRNA levels of several target genes were measured after one or seven days. The maximum force and stiffness were reduced by both statins after 7 days (p<0.05), while the cross sectional area was unaffected. Further, the collagen content was reduced by atorvastatin (p = 0.01) and the cell proliferation rate was decreased by both types of statins (p<0.05). Statin treatment also introduced increased mRNA levels of MMP-1, MMP-3, MMP-13, TIMP-1 and decreased levels of collagen type 1 and 3. In conclusion, statin treatment appears to have a negative effect on tendon matrix quality as seen by a reduced strength of the tendon constructs. Further, activated catabolic changes in the gene expression pattern and a reduced collagen content indicated a disturbed balance in matrix production of tendon due to statin administration.

The Rotator Cuff Organ: Integrating Developmental Biology, Tissue Engineering, and Surgical Considerations to Treat Chronic Massive Rotator Cuff Tears

The torn rotator cuff remains a persistent orthopedic challenge, with poor outcomes disproportionately associated with chronic, massive tears. Degenerative changes in the tissues that comprise the rotator cuff organ, including muscle, tendon, and bone, contribute to the poor healing capacity of chronic tears, resulting in poor function and an increased risk for repair failure. Tissue engineering strategies to augment rotator cuff repair have been developed in an effort to improve rotator cuff healing and have focused on three principal aims: (1) immediate mechanical augmentation of the surgical repair, (2) restoration of muscle quality and contractility, and (3) regeneration of native enthesis structure. Work in these areas will be reviewed in sequence, highlighting the relevant pathophysiology, developmental biology, and biomechanics, which must be considered when designing therapeutic applications. While the independent use of these strategies has shown promise, synergistic benefits may emerge from their combined application given the interdependence of the tissues that constitute the rotator cuff organ. Furthermore, controlled mobilization of augmented rotator cuff repairs during postoperative rehabilitation may provide mechanotransductive cues capable of guiding tissue regeneration and restoration of rotator cuff function. Present challenges and future possibilities will be identified, which if realized, may provide solutions to the vexing condition of chronic massive rotator cuff tears.

Pediatric Statin Administration: Navigating a Frontier with Limited Data

Increasingly, children and adolescents with dyslipidemia qualify for pharmacologic intervention. As they are for adults, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (statins) are the mainstay of pediatric dyslipidemia treatment when lifestyle modifications have failed. Despite the overall success of these drugs, the magnitude of variability in dose-exposure-response profiles contributes to adverse events and treatment failure. In children, the cause of treatment failures remains unclear. This review describes the updated guidelines for screening and management of pediatric dyslipidemia and statin disposition pathway to assist the provider in recognizing scenarios where alterations in dosage may be warranted to meet patients' specific needs.

Effect of Hypercholesterolemia on Fatty Infiltration and Quality of Tendon-to-Bone Healing in a Rabbit Model of a Chronic Rotator Cuff Tear: Electrophysiological, Biomechanical, and Histological Analyses

BACKGROUND

The incidence of healing failure after rotator cuff repair is high, and fatty infiltration is a crucial factor in healing failure.

PURPOSE

To verify the effect of hypercholesterolemia on fatty infiltration and the quality of tendon-to-bone healing and its reversibility by lowering the cholesterol level in a chronic tear model using the rabbit supraspinatus.

STUDY DESIGN

Controlled laboratory study.

METHODS

Forty-eight rabbits were randomly allocated into 4 groups (n = 12 each). After 4 weeks of a high-cholesterol diet (groups A and B) and a regular diet (groups C and D), the supraspinatus tendon was detached and left alone for 6 weeks and then was repaired in a transosseous manner (groups A, B, and C). Group D served as a control. Group A continued to receive the high-cholesterol diet until the final evaluation (6 weeks after repair); however, at the time of repair, group B was changed to a general diet with administration of a cholesterol-lowering agent (simvastatin). Histological evaluation of the fat-to-muscle proportion was performed twice, at the time of repair and the final evaluation, and an electromyographic (EMG) test, mechanical test, and histological test of tendon-to-bone healing were performed at the final evaluation.

RESULTS

For the EMG test, group A showed a significantly smaller area of compound muscle action potential compared with groups C and D (all P <.01), and group B showed a larger area than group A, almost up to the level of group C (P = .312). Similarly, group A showed significantly lower mechanical properties both in load-to-failure and stiffness compared with groups C and D (all P <.05). In addition, although not significantly different, the mechanical properties of group B were higher than those of group A (mean load-to-failure: group A = 42.01 N, group B = 58.23 N [P = .103]; mean stiffness: group A = 36.32 N/mm, group B = 47.22 N/mm [P = .153]). For the histological test, groups A and B showed a significantly higher fat-to-muscle proportion than did groups C and D at 6 weeks after detachment (all P <.05), but at the final evaluation, group B showed a decreased fat-to-muscle proportion (mean ± SD: from 64.02% ± 11.87% to 54.68% ± 10.47%; P = .146) compared with group A, which showed increased fat-to-muscle proportion (from 59.26% ± 17.80% to 78.23% ± 10.87%; P = .015). Groups B and C showed better tendon-to-bone interface structures than did group A, which showed coarse and poorly organized collagen fibers with fat interposition.

CONCLUSION

Hypercholesterolemia had a deleterious effect on fatty infiltration and the quality of tendon-to-bone repair site, and lowering hypercholesterolemia seemed to halt or reverse these harmful effects in this experimental model.

CLINICAL RELEVANCE

Systemic diseases such as hypercholesterolemia should be tightly controlled during the perioperative period of rotator cuff repair.

Effect of overuse-induced tendinopathy on tendon healing in a rat supraspinatus repair model

Supraspinatus tears often result in the setting of chronic tendinopathy. However, the typical repair model utilizes an acute injury. In recognition of that distinction, our laboratory developed an overuse animal model; however it is unclear whether induced overuse is necessary in the repair model. We studied the repair properties of overuse-induced tendons compared to normal tendons. We hypothesized that histological and mechanical properties would not be altered between the overuse-induced and normal tendons 1 and 4 weeks after repair. Thirty-one adult male Sprague-Dawley rats were subjected to either overuse or cage activity for 4 weeks prior to bilateral supraspinatus tendon repair surgery. Rats were sacrificed at 1 and 4 weeks post-surgery and evaluated for histology and mechanics. Results at 1 week showed no clear histologic changes, but increased inflammatory protein expression in overuse tendons. At 4 weeks, percent relaxation was slightly increased in the overuse group. No other alterations in mechanics or histology were observed. Our results suggest that the effects of the surgical injury overshadow the changes evoked by overuse. Because clinically relevant mechanical parameters were not altered in the overuse group, we conclude that when examining tendons 4 weeks after repair in the classic rat supraspinatus model, inducing overuse prior to surgery is likely to be unnecessary.

Upregulation of C-C chemokine receptor type 7 expression by membrane-associated prostaglandin E synthase-1/prostaglandin E2 requires glycogen synthase kinase 3β-mediated signal transduction in colon cancer cells

C-C chemokine receptor type 7 (CCR7) is involved in the development and progressions of chronic inflammatory diseases and cancer; therefore, signaling pathways that regulate CCR7 expression may represent novel molecular therapeutic targets. Previous studies by our group revealed that CCR7 is important in colon cancer progression and a is linked with cyclooxygenase (COX)‑2‑derived prostaglandin (PG)E2. Induction of COX‑2 and membrane‑associated PGE synthase 1 (mPGES‑1), which are overexpressed in numerous cancer types, cooperatively enhance PGE2 expression, which contributes to carcinogenesis and cancer progression. The present study investigated whether CCR7 expression is associated with the levels of mPGES‑1-derived PGE2. The results showed that mPGES‑1‑dependent release of PGE2 was markedly induced in colon cancer cells after transient transfection with mPGES‑1 overexpression vector, accompanied by elevated CCR7 expression. PGE2 levels and CCR7 expression were markedly attenuated in colon cancer cells in which mPGES‑1 was blocked, which identified mPGES‑1 as a potential therapeutic target for the regulation of CCR7 expression. Finally, overexpression of CCR7 was partly mediated through the AKT/glycogen synthase kinase 3β signaling pathway dependent on the binding of mPGES‑1-derived PGE2 to the prostaglandin EP4 receptor. Thus, in addition to inhibitors of mPGES‑1 expression, EP4 antagonists and AKT/GSK-3β inhibitors may emerge as potential therapeutics to reduce CCR7 expression in colon cancer.

The Effect of Cyclooxygenase Inhibition on Tendon-Bone Healing in an In Vitro Coculture Model

The effects of cyclooxygenase (COX) inhibition following the reconstruction of the anterior cruciate ligament remain unclear. We examined the effects of selective COX-2 and nonselective COX inhibition on bone-tendon integration in an in vitro model. We measured the dose-dependent effects of ibuprofen and parecoxib on the viability of lipopolysaccharide- (LPS-) stimulated and unstimulated mouse MC3T3-E1 and 3T3 cells, the influence on gene expression at the osteoblast, interface, and fibroblast regions measured by quantitative PCR, and cellular outgrowth assessed on histological sections. Ibuprofen led to a dose-dependent suppression of MC3T3 cell viability, while parecoxib reduced the viability of 3T3 cultures. Exposure to ibuprofen significantly suppressed expression of Alpl (P < 0.01), Bglap (P < 0.001), and Runx2 (P < 0.01), and although parecoxib reduced expression of Alpl (P < 0.001), Fmod (P < 0.001), and Runx2 (P < 0.01), the expression of Bglap was increased (P < 0.01). Microscopic analysis showed a reduction in cellular outgrowth in LPS-stimulated cultures following exposure to ibuprofen and parecoxib. Nonselective COX inhibition and the specific inhibition of COX-2 led to region-specific reductions in markers of calcification and cell viability. We suggest further in vitro and in vivo studies examining the biologic and biomechanical effects of selective and nonselective COX inhibition.