Preoperative Lymphocyte to Monocyte Ratio Can Be a Prognostic Factor in Arthroscopic Repair of Small to Large Rotator Cuff Tears

Exosomes derived from tendon stem/progenitor cells enhance tendon-bone interface healing after rotator cuff repair in a rat model

The rate of retear after surgical repair remains high. Mesenchymal stem cells (MSCs) have been extensively employed in regenerative medicine for several decades. However, safety and ethical concerns constrain their clinical application. Tendon Stem/Progenitor Cells (TSPCs)-derived exosomes have emerged as promising cell-free therapeutic agents. Therefore, urgent studies are needed to investigate whether TSPC-Exos could enhance tendon-bone healing and elucidate the underlying mechanisms. In this study, TSPC-Exos were found to promote the proliferation, migration, and expression of fibrogenesis markers in BMSCs. Furthermore, TSPC-Exos demonstrated an ability to suppress the polarization of M1 macrophages while promoting M2 macrophage polarization. In a rat model of rotator cuff repair, TSPC-Exos modulated inflammation and improved the histological structure of the tendon-bone interface, the biomechanical properties of the repaired tendon, and the function of the joint. Mechanistically, TSPC-Exos exhibited high expression of miR-21a-5p, which regulated the expression of PDCD4. The PDCD4/AKT/mTOR axis was implicated in the therapeutic effects of TSPC-Exos on proliferation, migration, and fibrogenesis in BMSCs. This study introduces a novel approach utilizing TSPC-Exos therapy as a promising strategy for cell-free therapies, potentially benefiting patients with rotator cuff tear in the future.

A Mesoporous Silica-Loaded Multi-Functional Hydrogel Enhanced Tendon Healing via Immunomodulatory and Pro-Regenerative Effects

Tendon injuries are pervasive orthopedic injuries encountered by the general population. Nonetheless, recovery after severe injuries, such as Achilles tendon injury, is limited. Consequently, there is a pressing need to devise interventions, including biomaterials, that foster tendon healing. Regrettably, tissue engineering treatments have faced obstacles in crafting appropriate tissue scaffolds and efficacious nanomedical approaches. To surmount these hurdles, an innovative injectable hydrogel (CP@SiO2), comprising puerarin and chitosan through in situ self-assembly, is pioneered while concurrently delivering mesoporous silica nanoparticles for tendon healing. In this research, CP@SiO2 hydrogel is employed for the treatment of Achilles tendon injuries, conducting extensive in vivo and in vitro experiments to evaluate its efficacy. This reults demonstrates that CP@SiO2 hydrogel enhances the proliferation and differentiation of tendon-derived stem cells, and mitigates inflammation through the modulation of macrophage polarization. Furthermore, using histological and behavioral analyses, it is found that CP@SiO2 hydrogel can improve the histological and biomechanical properties of injured tendons. This findings indicate that this multifaceted injectable CP@SiO2 hydrogel constitutes a suitable bioactive material for tendon repair and presents a promising new strategy for the clinical management of tendon injuries.

Translational studies of exosomes in sports medicine - a mini-review

This review in sports medicine focuses on the critical role of exosomes in managing chronic conditions and enhancing athletic performance. Exosomes, small vesicles produced by various cells, are essential for cellular communication and transporting molecules like proteins and nucleic acids. Originating from the endoplasmic reticulum, they play a vital role in modulating inflammation and tissue repair. Their significance in sports medicine is increasingly recognized, particularly in healing athletic injuries, improving articular cartilage lesions, and osteoarthritic conditions by modulating cellular behavior and aiding tissue regeneration. Investigations also highlight their potential in boosting athletic performance, especially through myocytes-derived exosomes that may enhance adaptability to physical training. Emphasizing a multidisciplinary approach, this review underlines the need to thoroughly understand exosome biology, including their pathways and classifications, to fully exploit their therapeutic potential. It outlines future directions in sports medicine, focusing on personalized treatments, clinical evaluations, and embracing technological advancements. This research represents a frontier in using exosomes to improve athletes' health and performance capabilities.

Erxian Decoction-induced serum exosomes slowed bone marrow mesenchymal stem cell senescence through mitophagy

OBJECTIVE

Erxian Decoction (EXD) is traditionally employed in the treatment of menopausal syndromes, although its underlying mechanisms remain largely undefined. Given that the senescence of bone marrow mesenchymal stem cells (BMSCs) is intertwined with organismal aging and associated diseases, this study endeavored to elucidate the influence of EXD on aging BMSCs and uncover the mechanisms through which EXD impedes BMSC senescence.

METHODS

Initially, we probed the anti-senescent mechanisms of EXD on BMSCs via network pharmacology. We subsequently isolated and identified exosomes from the serum of EXD-fed rats (EXD-Exos) and administered these to H2 O2 -induced aging BMSC. Assays were conducted to assess BMSC senescence indicators and markers pertinent to mitochondrial autophagy. Treatments with mitophagy inhibitors and activators were then employed to substantiate our findings.

RESULTS

Protein-protein interaction (PPI) network analyses spotlighted AKT1, TP53, TNF, JUN, VEGFA, IL6, CASP3 and EGFR as focal targets. Gene Ontology and Kyoto Encylcopedia of Genes and Genomes pathway analyses underscored oxidative stress, mitophagy and cell proliferation as pivotal processes. Our cellular assays ascertained that EXD-Exos mitigated H2 O2 -induced senescence phenotypes in BMSCs. Moreover, EXD-Exos ameliorated disrupted mitophagy in BMSCs, as evidenced by enhanced cellular membrane potential and diminished reactive oxygen species levels. Intriguingly, EXD-Exos also preserved the osteogenic differentiation potential of BMSCs while curtailing their adipogenic propensity.

CONCLUSION

Our findings compellingly suggest that EXD counteracts BMSC senescence by fostering mitophagy.

An assessment of factors associated with early postoperative stiffness in arthroscopic rotator cuff repair

BACKGROUND

Postoperative stiffness affects up to 20% of patients following arthroscopic rotator cuff repair. Recent evidence indicates that early postoperative stiffness may associated with lower retear rates. This study aimed to identify the independent predictors of early postoperative stiffness.

METHODS

A retrospective cohort study of 1526 rotator cuff repairs was performed. Range of motion at 6-week postop was used to identify stiff patients. Stiffness was defined as external rotation <27.5o or forward flexion <145o . Multiple logistic regression analysis was used to identify the independent predictors of 6-week stiffness.

RESULTS

The independent predictors for external rotation stiffness at 6-week postop were more recent cases (Wald = 60), restricted preoperative external rotation (Wald = 36), younger age (Wald = 21) and poorer surgeon-ranked tissue quality (Wald = 15). The independent predictors for forward flexion stiffness were more recent cases (Wald = 101), restricted preoperative forward flexion (Wald = 16) and external rotation (Wald = 13) and female patients (Wald = 12). All patients that developed early postoperative stiffness had recovered range of motion by 6 months to preoperative levels (P < 0.0001). A significantly greater proportion of younger patients (40-49) developed postoperative stiffness when compared to older patients aged 50-59 (P < 0.0062), 70-79 (P < 0.0126) and 80-89 (P < 0.004). Patients that retore had significantly greater average 6-week postoperative range of motion.

CONCLUSIONS

Patients earlier in the study were found to have greater postoperative range of motion, which coincided with a more aggressive rehabilitation program with less immobilization. Thus, the data supports the hypothesis that a temporary period of shoulder stiffness facilitates tendon repair and ultimately a better outcome post rotator cuff repair.

Long head of biceps tendon transposition for massive and irreparable rotator cuff tears: A systematic review and meta-analysis

BACKGROUND

Superior capsular reconstruction (SCR) with long head of biceps tendon (LHBT) transposition was developed to massive and irreparable rotator cuff tears (MIRCTs); however, the outcomes of this technique remain unclear.

AIM

To perform a systematic review of biomechanical outcomes and a meta-analysis of clinical outcomes after LHBT transposition for MIRCTs.

METHODS

We performed a systematic electronic database search on PubMed, EMBASE, and Cochrane Library. Studies of SCR with LHBT transposition were included according to the inclusion and exclusion criteria. Biomechanical studies were assessed for main results and conclusions. Included clinical studies were evaluated for quality of methodology. Data including study characteristics, cohort demographics, and outcomes were extracted. A meta-analysis was conducted of the clinical outcomes.

RESULTS

According to our inclusion and exclusion criteria, a total of six biomechanical studies were identified and reported an overall improvement in subacromial contact pressures and prevention of superior humeral migration without limiting range of motion (ROM) after LHBT transposition for MIRCTs. A total of five clinical studies were included in the meta-analysis of LHBT transposition outcomes, consisting of 253 patients. The results indicated that compared to other surgical methods for MIRCTs, LHBT transposition had advantages of more significant improvement in ROM (forward flexion mean difference [MD] = 6.54, 95% confidence interval [CI]: 3.07-10.01; external rotation [MD = 5.15, 95%CI: 1.59-8.17]; the acromiohumeral distance [AHD] [MD = 0.90, 95%CI: 0.21-1.59]) and reducing retear rate (odds ratio = 0.27, 95%CI: 0.15-0.48). No significant difference in American Shoulder and Elbow Surgeons score, visual analogue scale score, and University of California at Los Angles score was demonstrated between these two groups for MIRCTs.

CONCLUSION

In general, SCR with LHBT transposition was a reliable and economical technique for treating MIRCTs, both in terms of biomechanical and clinical outcomes, with comparable clinical outcomes, improved ROM, AHD, and reduced the retear rates compared to conventional SCR and other established techniques. More high-quality randomized controlled studies on the long-term outcomes of SCR with LHBT transposition are required to further assess.

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.

Mesenchymal stem cells and macrophages and their interactions in tendon-bone healing

Tendon-bone insertion injuries (TBI), such as anterior cruciate ligament (ACL) and rotator cuff injuries, are common degenerative or traumatic pathologies with a negative impact on the patient's daily life, and they cause huge economic losses every year. The healing process after an injury is complex and is dependent on the surrounding environment. Macrophages accumulate during the entire process of tendon and bone healing and their phenotypes progressively transform as they regenerate. As the "sensor and switch of the immune system", mesenchymal stem cells (MSCs) respond to the inflammatory environment and exert immunomodulatory effects during the tendon-bone healing process. When exposed to appropriate stimuli, they can differentiate into different tissues, including chondrocytes, osteocytes, and epithelial cells, promoting reconstruction of the complex transitional structure of the enthesis. It is well known that MSCs and macrophages communicate with each other during tissue repair. In this review, we discuss the roles of macrophages and MSCs in TBI injury and healing. Reciprocal interactions between MSCs and macrophages and some biological processes utilizing their mutual relations in tendon-bone healing are also described. Additionally, we discuss the limitations in our understanding of tendon-bone healing and propose feasible ways to exploit MSC-macrophage interplay to develop an effective therapeutic strategy for TBI injuries.

The Translational potential of this article

This paper reviewed the important functions of macrophages and mesenchymal stem cells in tendon-bone healing and described the reciprocal interactions between them during the healing process. By managing macrophage phenotypes, mesenchymal stem cells and the interactions between them, some possible novel therapies for tendon-bone injury may be proposed to promote tendon-bone healing after restoration surgery.

The predictive value of preoperative luteinizing hormone to follicle stimulating hormone ratio for ovulation abnormalities recovery after laparoscopic sleeve gastrectomy: A prospective cohort study

Introduction

Obesity-related ovulation abnormalities (OA) affect fertility. LSG is the most frequent bariatric operation. However, no research has identified a reliable indicator for predicting OA recovery after LSG. The purpose of this research was to examine the prognostic usefulness of preoperative the luteinizing hormone (LH) to follicle-stimulating hormone (FSH) ratio (LFR).

Methods

Our department conducted a prospective study from 2016 to 2021. Venous blood was typically tested 3 days before surgery to get the preoperative LFR. Descriptive data, preoperative and postoperative variables were also collected. Binary logistic regression related preoperative LFR with OA recovery. The receiver operating characteristic (ROC) curve evulated preoperative LFR's predictive capability.

Results

A total of 157 women with a complete follow-up of one year were included. LFR was the only factor linked with OA (P < 0.001). AUC (area under the ROC curve) = 0.915, cutoff = 1.782, sensitivity = 0.93, and specificity = 0.82.

Discussion

Overall, LSG has a favorable surgical result, with a %TWL of 66.082 ± 12.012 at 12 months postoperatively. Preoperative sexual hormone levels, as expressed by LFR, has the potential to predict the fate of OA following LSG at one year post-operatively.

Human bone marrow mesenchymal stem cell-derived extracellular vesicles inhibit shoulder stiffness via let-7a/Tgfbr1 axis

Shoulder stiffness (SS) is a common shoulder disease characterized by increasing pain and limited range of motion. SS is considered to be an inflammatory and fibrotic disorder pathologically. However, there is no consensus on the most effective conservative treatment for fibrosis. Given that human Bone Marrow Mesenchymal Stem Cell-derived extracellular vesicles (BMSC-EVs) displayed promising therapeutic effects for various tissues, we investigated the therapeutic effect of BMSC-EVs on fibrosis in a mice immobilization model and two cell models. By conducting a series of experiments, we found that BMSC-EVs can significantly inhibit the fibrogenic process both in vitro and in vivo. In detail, BMSC-EVs suppressed the aberrant proliferation, high collagen production capacity, and activation of fibrotic pathways in TGF-β-stimulated fibroblasts in vitro. Besides, in vivo, BMSC-EVs reduced cell infiltration, reduced fibrotic tissue in the shoulder capsule, and improved shoulder mobility. In addition, via exosomal small RNA sequencing and qPCR analysis, let-7a-5p was verified to be the highest expressed miRNA with predicted antifibrotic capability in BMSC-EVs. The antifibrotic capacity of BMSC-EVs was significantly impaired after the knockdown of let-7a-5p. Moreover, we discovered that the mRNA of TGFBR1 (the membrane receptor of transforming growth factor β) was the target of let-7a-5p. Together, these findings elucidated the antifibrotic role of BMSC-EVs in shoulder capsular fibrosis. This study clarifies a new approach using stem cell-derived EVs therapy as an alternative to cell therapy, which may clinically benefit patients with SS in the future.

Advances in traditional Chinese medicine as adjuvant therapy for diabetic foot

Diabetes mellitus (DM) is a complex disease that often causes multiple systemic complications that have become a major international public health problem. Diabetic foot (DF) is one of the severe and frequent chronic complications of DM due to vascular lesions and neuropathy. DF ulcers (DFU) affect approximately 15% of people with DM and are the leading cause of death and disability. The prevalence and recurrence of DF are worrisome, and morbidity and mortality are also on the rise, which poses a substantial socioeconomic burden. Treating DF is difficult for clinicians and requires multidisciplinary cooperation, combining local and systemic therapy to reduce amputation and case-fatality rates. Traditional Chinese Medicine (TCM) has received extensive attention due to noticeable therapeutic effects and few adverse reactions. In recent years, research on DF treatment by TCM has been increasing, and further progress has been made. TCM includes oral medication, injectable preparations, and adjuvant therapy. This article reviews the relevant research on TCM-related adjuvant therapy for DF. We describe current progress in TCM in terms of external application, acupuncture, massage, acupoint injection, foot bath, fumigation, and moxibustion, as well as the mechanisms involved.

Prognostic factors for improvement of shoulder function after arthroscopic rotator cuff repair: a systematic review

Background

The identification of factors that specify prognostic models for postoperative results should be based on the best scientific evidence and expert assessment. We aimed to identify, map, and evaluate potential prognostic factors for the improvement of shoulder function in patients undergoing arthroscopic rotator cuff repair.

Methods

Longitudinal primary studies of arthroscopic rotator cuff repair reporting any multivariable factor analyses for shoulder function improvement with an endpoint assessment of at least 6 months were included. We systematically searched EMBASE, Medline, and Scopus for articles published between January 2014 and June 2021. The risk of bias of included studies and the quality of evidence were assessed using the Quality in Prognosis Studies tool and an adapted Grading of Recommendations, Assessment, Development, and Evaluations framework.

Results

Overall, 24 studies including 73 outcome analyses were included. We classified younger age and smaller tear size as probably prognostic for a greater improvement in objective outcomes. Shorter symptom duration, absence of a worker compensation claim, low preoperative level of functional status, and high preoperative pain level were classified as probably prognostic for greater improvement in patient-reported outcome measures. The quality of the synthesized evidence was low. Twenty-one studies had an overall high risk of bias.

Conclusion

Six potential prognostic factors for shoulder function after arthroscopic rotator cuff repair were identified. Along with ongoing expert opinion assessments, they will feed into a prognostic model-building process.

Is there a correlation between preoperative neutrophil-to-lymphocyte, platelet-to-lymphocyte, and lymphocyte-to-monocyte ratios and postoperative pain in video-assisted thoracoscopic surgery?

Many thoracic surgery procedures are now performed with video-assisted thoracoscopic surgery (VATS). Postoperative pain is a common condition in patients undergoing VATS. In this study, we aimed to investigate whether neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR) are effective in evaluating postoperative pain in patients undergoing VATS.This prospective observational study was performed between March 2021 and September 2021 at a tertiary thoracic surgery center. The study included patients who had undergone elective VATS. Preoperative and postoperative NLR, PLR, LMR, hemogram values and postoperative visual analog scale (VAS) were recorded.A total of 105 patients were analyzed. A positive correlation was observed between postoperative monocyte, neutrophils and VAS resting and VAS cough levels in the early postoperative period. No significant correlation was found between preoperative and postoperative NLR, PLR, and LMR values and VAS rest and VAS cough values. When compared to the preoperative period, a negative correlation was found between the change in the postoperative LMR value and the VAS rest and VAS cough values in the early postoperative period.When compared to the preoperative period, the change in postoperative neutrophil, postoperative monocytes, and postoperative LMR values in patients undergoing VATS in thoracic surgery can be used as a guide in the objective evaluation of postoperative acute pain. It is the belief of the researchers that comprehensive new studies on this subject will contribute significantly to the determination of objective criteria in postoperative pain evaluation.

Preoperative Lymphocyte-to-Monocyte Ratio Can Indicate the Outcomes in Repair of I-III Degree Injury of Lateral Ankle Ligament

Background. This study is aimed at exploring the prognostic value of preoperative lymphocyte-to-monocyte ratio (LMR), an index of systemic inflammation before operation, in ankle lateral ligament repair (ALLR). Methods. A total of 213 I-III degrees injuries of lateral ankle ligament patients received ALLR and were followed up for more than 2 years. Univariate and multivariable linear regression analysis was used to determine the relationship between preoperative LMR and postoperative recovery. The evaluations of postoperative recovery include American Orthopaedic Foot and Ankle Society (AOFAS) score, Karlsson-Peter ankle score (KPAS), Cumberland Ankle Instability Tool (CAIT) score, Visual Analog Scale (VAS) score, and range of motion (ROM). The prognostic value of preoperative LMR was measured by receiver operating characteristic (ROC) curve. Results. 178 patients (178 ankles) were followed up successfully, with a follow-up of $2.82\pm 1.54$ years. Overall, the mean AOFAS, KPAS, CAIT and VAS scores, and ankle varus angle were significantly improved at the final follow-up. Univariate and multiple linear regression analysis showed that preoperative LMR was the only independent factor associated with postoperative function, ROM, and pain. The preoperative LMR of patients with poor recovery was significantly lower than that of patients with good recovery. Based on the ROC analysis, the cutoff value of preoperative LMR was 3.824. The clinical outcomes of patients with $\text{preoperative}\text{LMR}<3.824$ were significantly lower than that of patients with $\text{preoperative}\text{LMR}\ge 3.824$ . The corresponding specificity and sensitivity were 84.6% and 71.4%. Conclusion. The clinical outcomes of open or arthroscopic repair for ATFL injury are satisfactory. As a marker of systemic inflammation, preoperative LMR can be used as a prognostic indicator for ALLR.

Identification of Diagnostic Biomarkers Associated with Stromal and Immune Cell Infiltration in Fatty Infiltration After Rotator Cuff Tear by Integrating Bioinformatic Analysis and Machine-Learning

Purpose

The present study aimed to explore potential diagnostic biomarkers for fatty infiltration (FI) of the rotator cuff muscles after rotator cuff tear (RCT) and investigate the influence of stromal and immune cell infiltration on this pathology.

Methods

The GSE130447 and GSE103266 datasets were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified, and gene set enrichment analyses were performed by R software. Two machine learning algorithms, random forest and multiple support vector machine recursive feature elimination (mSVM-RFE), were used to screen candidate biomarkers. The diagnostic value of the screened biomarkers was further validated by the area under the ROC curve (AUC) in the GSE103266 dataset. Murine microenvironment cell population counter (mMCP-counter) method was employed to estimate stromal and immune cell infiltration of FI. The correlation between biomarkers and infiltrated immune and stromal cell subsets was further analyzed.

Results

A total of 2123 DEGs were identified. The identified DEGs were predominantly linked to immune system process, extracellular matrix organization and PPAR signalling pathway. FABP5 (AUC = 0.958) and MGP (AUC = 1) were screened as diagnostic biomarkers of FI. Stromal and immune cell infiltration analysis showed that monocytes, mast cells, vessels, endothelial cells and fibroblasts may be related to the process of FI. FABP5 and MGP were positively correlated with vessels whereas negatively correlated with monocytes and mast cells.

Conclusion

FABP5 and MGP can serve as diagnostic biomarkers of FI after RCT, and stromal and immune cell infiltration may play a crucial role in this pathology.

Conditioned medium of human bone marrow-derived stem cells promotes tendon-bone healing of the rotator cuff in a rat model

Rotator cuff repair is a common surgery in sports medicine. During the surgery, torn tendon was re-fixed onto the bony surface. The majority of patients gain good results. However, re-tear occurs in some patients. The reason under this phenomenon is that the normal tendon-bone enthesis cannot be reconstructed. In order to strengthen the tendon-bone healing and promote enthesis regeneration, numerous manners are tested, among which stem cell related therapies are preferred. Stem cells, due to the ability of multi-lineage differentiation, are widely used in regenerative medicine. However, safety and ethics concerns limit its clinical use. Recent studies found that it is the secretome of stem cells that is biologically effective. On ground of this, we, in the current study, collected the conditioned medium of human bone marrow-derived stem cells (hBMSC-CM) and tested whether this acellular method could promote tendon-bone healing in a rat model of rotator cuff repair. By using histological, radiological, and biomechanical methods, we found that hBMSC-CM promoted tendon-bone healing of the rat rotator cuff. Then, we noticed that hBMSC-CM exerted an impact on macrophage polarization both in vivo and in vitro by inhibiting M1 phenotype and promoting M2 phenotype. Further, we proved that the benefit of hBMSC-CM on tendon-bone healing was related to its regulation on macrophage. Finally, we proved that, hBMSC-CM influenced macrophage polarization, which was, at least partially, related to Smad2/3 signaling pathway. Based on the experiments above, we confirmed the benefit of hBMSC-CM on tendon-bone healing, which relied on its immune-regulative property. Considering the accessibility and safety of acellular hBMSC-CM, we believe it is a promising candidate clinically for tendon-bone healing.

The Serum from Patients with Secondary Frozen Shoulder Following Rotator Cuff Repair Induces Shoulder Capsule Fibrosis and Promotes Macrophage Polarization and Fibroblast Activation

PURPOSE

Disorders with systematic inflammation were prognostic for secondary frozen shoulder (sFS) following rotator cuff repair (RCR); however, how systematic inflammation affects sFS remains unclear. The aim of this study was to observe the effect of pre-operative serum from patients with sFS and the serum from those without on shoulder capsule in mice, and on macrophages and fibroblasts in vitro.

METHODS

Serum samples of a consecutive cohort of patients for RCR were collected pre-operatively. Three months after RCR, patients who developed sFS (Group S) were identified. Serum samples from gender- and age-matched controls without sFS (group NS) were also picked out. Firstly, the effect of serum on shoulder capsule fibrosis was observed histologically and biomechanically in a mouse model of RCR. Secondly, the roles of the serum on macrophage polarization and fibroblast activation were investigated, and the potentially involved signaling pathways were identified. Finally, inflammation and fibrosis-related cytokines in serum were quantified.

RESULTS

In our cohort, all patients had free pre-operative shoulder range of motion. Seven patients developed sFS at 3 months after surgery. Seven matched patients without sFS were selected as control. The inter-group difference of basic characteristics was not significant. Compared to the serum of group NS, the serum of group S significantly induced hypercellularity, capsular thickening, and range of motion deficiency in mice shoulders after RCR. Compared to the serum of group NS, samples of group S significantly promoted M2 polarization of THP-1 human macrophages and the activation of human capsule-derived fibroblasts. Meanwhile, Smad3 and p-Smad3 in macrophages and fibroblasts were significantly up-regulated. On the other hand, levels of inflammation and fibrosis-related cytokines were not significantly different between serum in group S and group NS.

CONCLUSION

Although all patients in this cohort had free range of motion pre-operatively, the pre-operative serum from patients with sFS at 3 months after RCR could act as a trigger of shoulder capsule fibrosis post-operatively. This effect may be related to its promotion on macrophage polarization to M2 phenotype and fibroblast activation.