Involvement of synovial matrix degradation and angiogenesis in oxidative stress-exposed degenerative rotator cuff tears with osteoarthritis

Advances with Platelet-Rich Plasma for Bone Healing

Despite significant advances in the understanding and delivery of osteosynthesis, fracture non-union remains a challenging clinical problem in orthopaedic surgery. To bridge the gap, basic science characterization of fracture healing provides a platform to identify and target biological strategies to enhance fracture healing. Of immense interest, Platelet-rich plasma (PRP) is a point of care orthobiologic that has been extensively studied in bone and soft tissue healing given its relative ease of translation from the benchtop to the clinic. The aim of this narrative review is to describe and relate pre-clinical in-vitro and in-vivo findings to clinical observations investigating the efficacy of PRP to enhance bone healing for primary fracture management and non-union treatment. A particular emphasis is placed on the heterogeneity of PRP preparation techniques, composition, activation strategies, and delivery. In the context of existing data, the routine use of PRP to enhance primary fracture healing and non-union management cannot be supported. However, it is acknowledged that extensive heterogeneity of PRP treatments in clinical studies adds obscurity; ultimately, refinement (and consensus) of PRP treatments for specific clinical indications, including repetition studies are warranted.

Shoulder Intra-Articular Temperature Is Higher In Patients With Small Rotator Cuff Tears Compared With Patients Who Have Larger Tears

Purpose

The purpose of this study was to determine whether the intra-articular temperature of the shoulder correlates with the size of the tendon tear in patients with rotator cuff tears (RCTs).

Methods

The shoulder intra-articular temperature of 75 consecutive (32 female, 43 male; mean age 61.12; standard deviation = 7.10) patients who underwent arthroscopic rotator cuff repair was measured with a digital thermometer, at first in 2 points (biceps anchor and glenoid labrum) during dry arthroscopy, followed by a third measurement during wet arthroscopy. A fourth measurement, represented by the patient's axillary body temperature, was taken upon admission. The RCTs were classified during surgery according to the Southern California Orthopedic Institute classification system as small, large, and massive. Data were submitted for statistical analysis.

Results

The intra-articular temperature differs in patients with different-sized RCTs regardless of the location of the thermometer. A significantly higher temperature was found in patients with small RCTs (36.2°C ± 0.57°C) (P < .01). When the in-flow of the arthroscopic fluid was opened, the temperature dropped to an average of 24.5°C.

Conclusions

The shoulder intra-articular temperature was significantly associated with RCT size. A significantly higher temperature was found in small RCTs. No correlation was found between age and sex, age and RCT size, sex and RCT size, or sex and temperature.

Clinical Relevance

An early diagnosis and treatment of RCTs may avoid further degeneration and damage of the tendon caused by the increased temperature.

Effects and action mechanisms of individual cytokines contained in PRP on osteoarthritis

Osteoarthritis (OA) is defined as a degenerative joint disease that can affect all tissues of the joint, including the articular cartilage, subchondral bone, ligaments capsule, and synovial membrane. The conventional nonoperative treatments are ineffective for cartilage repair and induce only symptomatic relief. Platelet-rich plasma (PRP) is a platelet concentrate derived from autologous whole blood with a high concentration of platelets, which can exert anti-inflammatory and regenerative effects by releasing multiple growth factors and cytokines. Recent studies have shown that PRP exhibits clinical benefits in patients with OA. However, high operational and equipment requirements greatly limit the application of PRP to OA treatment. Past studies have indicated that high-concentration PRP growth factors and cytokines may be applied as a commercial replacement for PRP. We reviewed the relevant articles to summarize the feasibility and mechanisms of PRP-based growth factors in OA. The available evidence suggests that transforming growth factor-α and β, platelet-derived growth factors, epidermal growth factor, insulin-like growth factor-1, and connective tissue growth factors might benefit OA, while vascular endothelial growth factor, tumor necrosis factor-α, angiopoietin-1, and stromal cell derived factor-1α might induce negative effects on OA. The effects of fibroblast growth factor, hepatocyte growth factor, platelet factor 4, and keratinocyte growth factor on OA remain uncertain. Thus, it can be concluded that not all cytokines released by PRP are beneficial, although the therapeutic action of PRP has a valuable potential to improve.

N-Acetyl-L-cysteine facilitates tendon repair and promotes the tenogenic differentiation of tendon stem/progenitor cells by enhancing the integrin α5/β1/PI3K/AKT signaling

BACKGROUND

Tendon injury is associated with oxidative stress, leading to reactive oxygen species (ROS) production and inflammation. N-acetyl-L-cysteine (NAC) is a potent antioxidant. However, how NAC affects the biological functions of tendon stem/progenitor cells (TSPCs) and tendon repair has not been clarified.  METHOD: The impacts of NAC on the viability, ROS production, and differentiation of TSPCs were determined with the cell counting kit-8, fluorescence staining, Western blotting, and immunofluorescence. The effect of NAC on gene transcription in TSPCs was analyzed by transcriptomes and bioinformatics and validated by Western blotting. The potential therapeutic effect of NAC on tendon repair was tested in a rat model of Achilles tendon injury.

RESULTS

Compared with the untreated control, treatment with 500 µM NAC greatly promoted the proliferation of TSPCs and significantly mitigated hydrogen peroxide-induced ROS production and cytotoxicity in vitro. NAC treatment significantly increased the relative protein expression of collagen type 1 alpha 1 (COL1A1), tenascin C (TNC), scleraxis (SCX), and tenomodulin (TNMD) in TPSCs. Bioinformatics analyses revealed that NAC modulated transcriptomes, particularly in the integrin-related phosphoinositide 3-kinase (PI3K)/AKT signaling, and Western blotting revealed that NAC enhanced integrin α5β1 expression and PI3K/AKT activation in TSPCs. Finally, NAC treatment mitigated the tendon injury, but enhanced the protein expression of SCX, TNC, TNMD, and COLIA1 in the injured tissue regions of the rats.

CONCLUSION

NAC treatment promoted the survival and differentiation of TSPCs to facilitate tendon repair after tendon injury in rats. Thus, NAC may be valuable for the treatment of tendon injury.

Systematic identification of aberrant non-coding RNAs and their mediated modules in rotator cuff tears

Background: Rotator cuff tears (RCT) is the most common cause of shoulder dysfunction, however, its molecular mechanisms remain unclear. Non-coding RNAs(ncRNAs), such as long ncRNA (lncRNA), microRNA (miRNA) and circular RNA (circRNA), are involved in a variety of diseases, but little is known about their roles in RCT. Therefore, the purpose of this study is to identify dysregulated ncRNAs and understand how they influence RCT.

Methods: We performed RNA sequencing and miRNA sequencing on five pairs of torn supraspinatus muscles and matched unharmed subscapularis muscles to identify RNAs dysregulated in RCT patients. To better comprehend the fundamental biological processes, we carried out enrichment analysis of these dysregulated mRNAs or the co-expressed genes of dysregulated ncRNAs. According to the competing endogenous RNA (ceRNA) theory, we finally established ceRNA networks to explore the relationship among dysregulated RNAs in RCT.

Results: A total of 151 mRNAs, 38 miRNAs, 20 lncRNAs and 90 circRNAs were differentially expressed between torn supraspinatus muscles and matched unharmed subscapularis muscles, respectively. We found that these dysregulated mRNAs, the target mRNAs of these dysregulated miRNAs or the co-expressed mRNAs of these dysregulated ncRNAs were enriched in muscle structure development, actin-mediated cell contraction and actin binding. Then we constructed and analyzed the ceRNA network and found that the largest module in the ceRNA network was associated with vasculature development. Based on the topological properties of the largest module, we identified several important ncRNAs including hsa_circ_0000722, hsa-miR-129-5p and hsa-miR-30c-5p, whose interacting mRNAs related to muscle diseases, fat and inflammation.

Conclusion: This study presented a systematic dissection of the expression profile of mRNAs and ncRNAs in RCT patients and revealed some important ncRNAs which may contribute to the development of RCT. Such results could provide new insights for further research on RCT.

Blood Flow in the Anterior Humeral Circumflex Artery Reflects Synovial Inflammation of the Shoulder Joint in Rotator Cuff Tears

Background

An association has been reported between rotator cuff tear and inflammation. We hypothesized that blood flow in the anterior humeral circumflex artery would reflect synovial inflammation in the shoulder. This study aimed to clarify the association of blood flow in the anterior humeral circumflex artery with synovial inflammation and shoulder pain in patients with rotator cuff tears.

Methods

In this prospective, cross-sectional study, tissue samples from the synovium in the rotator interval were obtained from 33 patients undergoing arthroscopic rotator cuff repair. Reverse transcription-polymerase chain reaction and real-time polymerase chain reaction were performed to determine the messenger RNA expression of inflammatory mediators, growth factors, and matrix metalloproteinases. Additional tissue samples were fixed for histologic evaluation. Before surgery, we measured the peak systolic velocity in the anterior humeral circumflex artery using pulse Doppler ultrasonography.

Results

The peak systolic velocity in the anterior humeral circumflex artery was positively correlated with the messenger RNA expression of interleukin 1β, interleukin 8, and matrix metalloproteinase 3 genes (r = 0.49, P = .004; r = 0.55, P = .001; and r = 0.39, P = .026, respectively), as well as histologic synovitis scores (r = 0.48, P = .005). Additionally, it was significantly higher in patients with resting pain than in those without resting pain (P = .048).

Conclusion

The peak systolic velocity in the anterior humeral circumflex artery is associated with the severity of synovial inflammation. Our results suggest that assessing the peak systolic velocity in the anterior humeral circumflex artery is useful for evaluating the severity of synovial inflammation.

Roles of Oxidative Stress in Acute Tendon Injury and Degenerative Tendinopathy-A Target for Intervention

Both acute and chronic tendon injuries are disabling sports medicine problems with no effective treatment at present. Sustained oxidative stress has been suggested as the major factor contributing to fibrosis and adhesion after acute tendon injury as well as pathological changes of degenerative tendinopathy. Numerous in vitro and in vivo studies have shown that the inhibition of oxidative stress can promote the tenogenic differentiation of tendon stem/progenitor cells, reduce tissue fibrosis and augment tendon repair. This review aims to systematically review the literature and summarize the clinical and pre-clinical evidence about the potential relationship of oxidative stress and tendon disorders. The literature in PubMed was searched using appropriate keywords. A total of 81 original pre-clinical and clinical articles directly related to the effects of oxidative stress and the activators or inhibitors of oxidative stress on the tendon were reviewed and included in this review article. The potential sources and mechanisms of oxidative stress in these debilitating tendon disorders is summarized. The anti-oxidative therapies that have been examined in the clinical and pre-clinical settings to reduce tendon fibrosis and adhesion or promote healing in tendinopathy are reviewed. The future research direction is also discussed.

Histological Features of Osteoarthritis in a State of Decompensation

Degenerative pathology of the musculoskeletal system is one of the main reasons for decreased mobility in patients of the older age group. Increasing the life expectancy leads to predominance non-epidemic pathology in all developed countries. Therefore, degenerative diseases of musculoskeletal system have not only medical significance but also social significance. Objective is studying the morphological features of synovial environment of the decompensated osteoarthritic (OA) knee joint. Structural features of subchondral bone, hyaline cartilage of the femur and tibia, the articular capsule, menisci and ligamentous apparatus of the knee joint were studied in 64 patients who underwent total knee arthroplasty at the Department of Traumatology and Orthopedics Bashkirian State Medical University in the period from 2015 to 2020. Material selection, preparation of histological samples, staining with hematoxylin-eosin, microscopy was performed. Adaptive signs of articular cartilage of the femoral condyles manifest in the form of cartilage tissue rearrangement, which are most pronounced in the central zone of the cartilage. At the same time, the phenomena of decompensation and significant areas of destruction are noted. Also, the subchondral bone was replaced with connective tissue with subsequent sclerosis. This sclerosis subsequently led to the decompensation of structures of the hyaline cartilage in the deep and middle zones. Destructive and dystrophic processes were noted in the knee joint menisci. Articular cartilage was replaced with granulation tissue with subsequent invasion of blood vessels. Cruciate ligaments in patients with OA show signs of adaptation due to expansion of endothenonium layers between bundles of collagen fibers and an increase in the diameter of blood vessels.

Platelet-Rich Plasma for Bone Fracture Treatment: A Systematic Review of Current Evidence in Preclinical and Clinical Studies

Background: Recently, there is an increasing interest in the therapeutic potential of platelet-rich plasma (PRP) for bone fracture treatment. Nevertheless, the effect of PRP for bone fracture treatment remains controversial and is still a matter of discussion. Therefore, we performed a systematic review to evaluate the efficacy and safety of PRP injection for treatment of bone fracture. Methods: The main bibliographic databases, including Medline, PubMed, Embase, Web of Science, and the Cochrane library, were comprehensively searched for studies focusing on the application of platelet-rich plasma (PRP) on bone fracture treatment. All relevant articles were screened for eligibility and subdivided into the preclinical and clinical studies. Data were extracted and presented systematically. Results: Finally, twenty-six in vitro preclinical studies (basic studies), nine in vivo preclinical studies (animal studies), and nine clinical studies, met the selection criteria, and were included in the present systematic review. Preclinical studies showed an overall positive effect of PRP on osteoblast-like cells in vitro and bone healing in animal models. The most used treatment for bone fracture in animal and clinical studies is fixation surgery combined with PRP injection. The clinical studies reported PRP shortened bony healing duration, and had no positive effect on improving the healing rate of closed fractures. However, the results of functional outcomes are controversial. Additionally, compared with control group, PRP would not increase the rate of postoperative wound infection. Conclusion: The present systematic review confirmed the continuing interests of PRP as an additional treatment for bone fracture. Preclinical studies highlighted the potential value of PRP as promising therapy for bone fracture. However, the preclinical evidence did not translate into a similar result in the clinical studies. In addition, types of fractures and procedures of PRP preparation are heterogeneous in enrolled studies, which might result in controversial results. Meanwhile, characteristics of PRP, such as platelet concentration, the numbers of leukocytes, still need to be determined and further research is required.

Expression of long-chain noncoding RNA GAS5 in osteoarthritis and its effect on apoptosis and autophagy of osteoarthritis chondrocytes

OBJECTIVE

To investigate the expression of long-chain noncoding RNA GAS5 in osteoarthritis (OA) and the effect of silencing GAS5 on autophagy of osteoarthritis chondrocytes (OACs).

METHODS

OA rat models were constructed by cutting the anterior cruciate ligament, and the expressions of GAS5 in rat cartilage tissues at 4 weeks (early OA) and 12 weeks (late OA) after modeling were detected. The rat chondrocytes were isolated, cultured and transfected with si-GAS5 to silencing GAS5. Then, the changes of apoptosis and autophagy levels of OA chondrocytes were detected by transfection of GFP-LC3 and flow cytometry. Bioinformatic tools were used to analyze the miRNA binding to GAS5 and the downstream target genes, then luciferase reporter assay and GDC-0349 (inhibitor of mTOR) were used to verify their relationships.

RESULTS

The expression of GAS5 in cartilage tissue of OA rats was higher than control, which was higher in late OA than that in early OA. After silencing the GAS5, the autophagy ability of OACs was increased and the apoptosis rate was decreased. GAS5 was able to bind to miR-144 and regulate the expressin of mTOR. mTOR inhibitor GDC-0349 could reverse the inhibition of GAS5 on autophagy but could not reverse its effect on apoptosis.

CONCLUSION

GAS5 expresses highly in OA cartilage tissues and increases with the progression of OA. GAS5 inhibits autophagy and promotes the apoptosis of OACs, and the inhibition of autophagy may be related to its regulation of mTOR.

lncRNAs: function and mechanism in cartilage development, degeneration, and regeneration

With the increasing incidence of cartilage-related diseases such as osteoarthritis (OA) and intervertebral disc degeneration (IDD), heavier financial and social burdens need to be faced. Unfortunately, there is no satisfactory clinical method to target the pathophysiology of cartilage-related diseases. Many gene expressions, signaling pathways, and biomechanical dysregulations were involved in cartilage development, degeneration, and regeneration. However, the underlying mechanism was not clearly understood. Recently, lots of long non-coding RNAs (lncRNAs) were identified in the biological processes, including cartilage development, degeneration, and regeneration. It is clear that lncRNAs were important in regulating gene expression and maintaining chondrocyte phenotypes and homeostasis. In this review, we summarize the recent researches studying lncRNAs’ expression and function in cartilage development, degeneration, and regeneration and illustrate the potential mechanism of how they act in the pathologic process. With continued efforts, regulating lncRNA expression in the cartilage regeneration may be a promising biological treatment approach.

Differential Expression of Renin-Angiotensin System-related Components in Patients with Rheumatoid Arthritis and Osteoarthritis

BACKGROUND

The purpose of this study was to demonstrate the role of renin-angiotensin system (RAS)-related components, vascular endothelial growth factor (VEGF) and atrial metalloproteinase-13 (MMP-13) in synovial tissue and synovial fluid from patients with rheumatoid arthritis (RA) and osteoarthritis (OA).

MATERIALS AND METHODS

Thirty-four patients with RA and 41 patients with OA were included in the study. Renin, angiotensin-converting enzyme (ACE), VEGF and MMP-13 protein levels in the synovial fluid were measured by enzyme-linked immunosorbent assay. Quantitative real-time polymerase chain reaction analysis, western blot analysis and immunohistochemistry were used to quantify renin, ACE, angiotensin type 1 and type 2 receptors, VEGF and MMP-13 in OA and RA. Additionally, the correlation was determined by Pearson's coefficient.

RESULTS

In synovial fluid, expression levels of renin, ACE, VEGF and MMP-13 in patients with RA were significantly higher than those in patients with OA. In synovial tissue, the RAS components VEGF and MMP-13 were also elevated in patients with RA. The results of immunohistochemistry in synovial tissue also showed that the RAS components VEGF and MMP-13 were significantly increased in patients with RA. Notably, the Pearson coefficient demonstrated that the levels of the RAS components were positively correlated with the expression of VEGF and MMP-13 in OA and RA.

CONCLUSIONS

The present results suggest that RAS-related components in RA and OA, including renin, ACE, angiotensin type 1 and type 2 receptors, are associated with increased expression of VEGF and play an important role in angiogenesis. Furthermore, there was a significant positive correlation between the expression of VEGF and MMP-13.

The critical shoulder angle: can it be sufficient to reflect the shoulder joint without the humeral head?

HYPOTHESIS

We hypothesized that a new method considering the humeral head would distinguish rotator cuff tears (RCTs) and osteoarthritis (OA) better than the critical shoulder angle (CSA).

METHODS

A total of 1011 patients were tested in this study and divided into 4 groups: those with RCTs (n = 493), those with OA (n = 73), those with anterior instability (n = 361), and those with adhesive capsulitis (n = 84). The CSA and new radiologic parameters including the humeral head were measured in the true anterior-to-posterior view: the Y angle connecting the lower end of the glenoid (LG), the center of the humeral head (CH), and the upper end of the glenoid (UG); the G angle connecting UG, CH, and the lateral tip of the acromion; the YG angle connecting LG, CH, and the lateral tip of the acromion; and the R angle connecting UG, LG, and CH.

RESULTS

The CSA and G angle were the largest in the RCT group (34.2° and 70.4°, respectively; P < .001) and the smallest in the OA group (29.8° and 61.7°, respectively; P < .001). The Y angle was the largest in the OA group (82.8°, P < .001). The R angle in the RCT group (52.9°) was significantly larger than that in the OA group, which was the smallest among the groups (48.0°; P < .001). The CSA was correlated with the G and YG angles in the RCT group, whereas the CSA was correlated with the Y, G, and R angles in the OA group (P < .05). The CSA showed the highest correlation with the size of RCTs (correlation coefficient = 0.138).

CONCLUSION

The Y, G, and R angles reflected the lesions of RCTs or OA. The CSA showed good correlations with the new radiologic parameters, and it had the highest correlation coefficient with the size of RCTs.

The clinical efficacy of using autologous platelet-rich plasma in total hip arthroplasty: A retrospective comparative study

This study evaluated whether intra-articular platelet-rich plasma (PRP) might prevent postoperative bleeding in total hip arthroplasty (THA).In this study, 260 hips that underwent THA were evaluated randomly by paramedical staffs, 130 of which involved the intraoperative use of PRP, and 130 of which served as control group. Postoperative blood loss (drain bag volume), estimated blood loss, and change in hemoglobin (Hb) at day 1, 2, 4, and 7 were analyzed, respectively.PRP-treated group had a significant decrease in mean postoperative blood loss (92.6 ± 168.2 mL) compared to control group (682.3 ± 185.5 mL, P < .01). The mean postoperative estimated blood loss (526.1 ± 236.1 mL) in the PRP-treated group was significantly less than that in the control group (629.2.2 ± 142.3 mL, P < .01). There was a statistically significant difference in Hb value (mg/dL) at day 1, 2, 4, and 7 (-1.35 vs -1.98, -1.59 vs -2.52, -1.96 vs -2.82, and -1.76 vs -2.47, P < .05).We found a significant reduction in postoperative blood loss (drain bag volume), estimated blood loss, and change in Hb after the use of autologous platelet gel in patients of THA, and PRP appears to be effective in reducing postoperative bleeding in THA.

Egr-1 increases angiogenesis in cartilage via binding Netrin-1 receptor DCC promoter

Background

Osteoarthritis (OA) is a joint disease characterized by degradation of cartilage. The etiology of OA is still unclear. Vascular endothelial growth factor (VEGF) plays a key role of angiogenesis in the pathogenesis of OA and contributes to the angiogenesis of NT-1/DCC. Whether or not NT-1/DCC and VEGF interact in regulating angiogenesis of OA cartilage is not known.

Methods

Histological studies for CD34, VEGF, and safranin-O staining were performed to determine angiogenesis and cartilage tissue injury. ELISA indicated the level of pro-inflammation cytokines. Immunoblotting, immunoprecipitation, and electrophoretic mobility shift assay (EMSA) were performed to assay the expression and function of NT-1/DCC-VEGF signaling pathway.

Results

Our data indicated that VEGF expression was increased in cartilage tissue from OA rats, while the chondrocytes were disorganized, and cartilage degeneration was increasing in OA rats. The inflammation factors in articular cavity fluid were higher in the OA rats than in the sham. The protein expression of NT-1, DCC, and VEGF were increased in osteoarthritic cartilage. DCC was involved in the positive regulation of osteoarthritic angiogenesis by VEGF. Egr-1 expression was higher in OA rats than in sham rats. Egr-1 is a regulator of DCC promoter activity, and the binding is higher in OA rats than in sham rats.

Conclusion

Our present study provides a mechanism by which Egr-1 induced angiogenesis via NT-1/DCC-VEGF pathway.