Yaying Sun

Hydroxyapatite-doped polycaprolactone nanofiber membrane improves tendon–bone interface healing for anterior cruciate ligament reconstruction

Hamstring tendon autograft is a routine graft for anterior cruciate ligament (ACL) reconstruction. However, ways of improving the healing between the tendon and bone is often overlooked in clinical practice. This issue can be addressed by using a biomimetic scaffold. Herein, a biomimetic nanofiber membrane of polycaprolactone/nanohydroxyapatite/collagen (PCL/nHAp/Col) is fabricated that mimics the composition of native bone tissue for promoting tendon–bone healing. This membrane has good cytocompatibility, allowing for osteoblast cell adhesion and growth and bone formation. As a result, MC3T3 cells reveal a higher mineralization level in PCL/nHAp/Col membrane compared with PCL membrane alone. Further in vivo studies in ACL reconstruction in a rabbit model shows that PCL/nHAp/Col-wrapped tendon may afford superior tissue integration to nonwrapped tendon in the interface between the tendon and host bone as well as improved mechanical strength. This study shows that PCL/nHAp/Col nanofiber membrane wrapping of autologous tendon is effective for improving tendon healing with host bone in ACL reconstruction.

Mussel-Inspired Artificial Grafts for Functional Ligament Reconstruction.

The development of an artificial graft with distinct osteogenetic activity to enhance osseointegration and to induce the formation of biomimetic tissue structure for ligament reconstruction remains a significant challenge. Inspired by mussels, biomimetic calcium phosphate apatite/polydopamine hybridized-polyethylene terephthalate (APA/PDA-PET) grafts were successfully prepared. The efficacy and mechanism of APA/PDA-PET grafts to induce osseointegration were systematically investigated. The results from the in vitro study indicated that the prepared APA/PDA-PET grafts support the attachment of bone marrow stromal cells (BMSCs) and stimulate the proliferation and osteogenic/angiogenic differentiation of BMSCs via activation of the PKC/p-ERK1/2 signaling pathway. In vivo, histological and radiological results further demonstrate that the APA/PDA-PET grafts significantly improve osseointegration by inducing the formation of new bone tissue and the fibrocartilage transitional zone compared with pure PET grafts. In addition, the pull-out strength of the APA/PDA-PET grafts is significantly higher than that of the pure PET grafts 12 weeks after surgery. These results suggest that this mussel-inspired biomimetic method is an effective strategy for modifying artificial grafts, and the prepared APA/PDA-PET grafts, which possess a beneficial interface, can significantly improve in vivo osseointegration for ligament reconstruction via the synergistic effect of polydopamine and apatite.

miR-146a-5p acts as a negative regulator of TGF-β signaling in skeletal muscle after acute contusion.

Growing evidence suggests the importance of microRNAs (miRNAs) in stress signaling pathways. Transforming growth factor-β (TGF-β) is a potent cytokine that promotes the development of skeletal muscle fibrosis after acute contusion. However, how miRNAs are involved in TGF-β signaling and confer the robustness of TGF-β-induced fibrotic response remains to be fully elucidated. Here, we demonstrated that miR-146a-5p (miR-146) levels were reduced in a fibrotic mouse model after acute muscle contusion. It was also found that TGF-β treatment decreased the expression of miR-146 in vitro in a dose- and time-dependent manner. In addition, overexpression of Smad3 and Samd4, two key players in TGF-β signaling, suppressed the expression of miR-146 in muscle cells. Overexpression of miR-146 inhibited the expressions of fibrosis markers both in vitro and in vivo. Moreover, increase in the expression of miR-146 in muscle cells was able to attenuate the effect of TGF-β on the expressions of fibrosis markers. Mechanistic analysis revealed that Smad4 is a direct target of miR-146 in muscle cells. Furthermore, the anti-fibrotic effect of miR-146 could be blocked by overexpression of Smad4 in vivo. These results suggest that Smad4 is down-regulated by miR-146 in skeletal muscle. Taken together, our results indicate that the anti-fibrotic miR-146 is a component of TGF-β signaling. It is down-regulated by Smad protein, and can inhibit the expression of Smad4. Our study suggests that miR-146 might have a therapeutic potential to reduce skeletal muscle fibrosis after injury.

Intra-articular Steroid Injection for Frozen Shoulder: A Systematic Review and Meta-analysis of Randomized Controlled Trials With Trial Sequential Analysis

Background: Intra-articular steroid injection is a common intervention for frozen shoulder (FS). Purpose: This review aimed to illustrate the effects of intra-articular steroid injection for FS. Study Design: Systematic review and meta-analysis. Methods: PubMed, Embase, and the Cochrane Library were searched for randomized controlled trials (RCTs) comparing intra-articular steroid injection with no injection or sham injections for FS. Visual analog scale (VAS) pain scores were the primary outcome measure. Secondary outcome measures included passive external rotation, abduction, flexion, internal rotation, and functional scores. Complication rates were the safety outcome measure. Comparisons were performed with mean differences (MDs) and 95% confidence intervals (95% CIs). Three time intervals were analyzed: 4 to 6 weeks, 12 to 16 weeks, and 24 to 26 weeks postintervention. Trial sequential analysis was used to verify the pooled results. Line charts were drawn to view the recovery trend in both the intervention and control groups. Results: Eight RCTs with 416 patients were included. Compared with controls, patients who received intra-articular steroid injection had significantly reduced VAS pain scores at 4 to 6 weeks (MD, 1.28 cm [95% CI, 0.75 to 1.82]), 12 to 16 weeks (MD, 1.00 cm [95% CI, 0.47 to 1.52]), and 24 to 26 weeks (MD, 0.65 cm [95% CI, 0.19 to 1.10]) postinjection. Trial sequential analysis confirmed the pooled results at 4 to 6 weeks and 12 to 16 weeks but not at 24 to 26 weeks. Patients who received intra-articular steroid injection had improved passive external rotation, abduction, and flexion and Shoulder Pain and Disability Index (SPADI) scores at all 3 time intervals, as well as improved American Shoulder and Elbow Surgeons (ASES) scores at 12 to 16 weeks (MD, 12.20 [95% CI, 2.55 to 21.85]). No difference was noticed in Constant scores (MD, 5.70 [95% CI, –0.59 to 11.99]) or internal rotation except at 12 to 16 weeks (MD, 0.81° [95% CI, 0.18° to 1.44°]) and 24 to 26 weeks (MD, 3.88° [95% CI, 0.51° to 7.25°]) between steroid injection and placebo. Complication rates were 1.78% for facial flushing, 0.71% for dizziness owing to vasovagal reactions during injection, 1.07% for chest or shoulder pain, and 0.36% for nausea. Line charts improved in both groups. Conclusion: Intra-articular steroid injection is effective and safe for FS and relieves pain, improves functional performance, and increases range of motion. The effects are significant at 4 to 6 and 12 to 16 weeks postintervention and may last as long as 24 to 26 weeks.

Steroid Injection and Nonsteroidal Anti-inflammatory Agents for Shoulder Pain: A PRISMA Systematic Review and Meta-Analysis of Randomized Controlled Trials

AbstractAdvantages and possible risks associated with steroid injection compared with nonsteroidal anti-inflammatory drugs (NSAIDs) for shoulder pain are not fully understood.To compare the efficiency and safety of steroid injection versus NSAIDs for patients with shoulder pain.PubMed, Embase, and the Cochrane Library were searched through July 2015.Study eligibility criteria, participants, and interventions: randomized controlled trials (RCTs) that assessed steroid injection versus NSAIDs for patients with shoulder pain.Study appraisal and synthesis methods: predefined primary efficacy outcome was functional improvement; and secondary efficacy outcomes included pain relief and complications. Relative risks (RRs) and standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated using a random-effects model accounting for clinical heterogeneity.Eight RCTs involving 465 participants were included in the meta-analysis. Five trials compared steroid injection with oral NSAIDs, and 3 compared steroids injection with NSAIDs injection. Compared with steroid injection, oral NSAIDs were less effective in 4 or 6 weeks for functional improvement (SMD 0.61; 95% CI, 0.08–1.14; P = 0.01), while there was no significant difference in pain relief (SMD 0.45; 95% CI, −0.50–1.40; P < 0.00001) or complication rate (RR 1.10; 95% CI, 0.26–4.58; P = 0.29). Meta-analysis was not performed for NSAIDs injection due to considerable heterogeneity. Conflicting results were observed in favor of either steroid or NSAIDs injection.Not all diseases that can lead to shoulder pain were included, detailed intervention protocols were inconsistent across studies, and some estimated data were input into comparison while some data were lost, which could exert an influence on pooled results.Steroid injection, compared with oral NSAIDs, provides slightly more improvement in shoulder function without superiority in pain relief or risk of complications at 4 to 6 weeks.Treatment decision should be made based on diseases. NSAIDs injection might be a treatment method for shoulder pain.

Steroid Injection Versus Physiotherapy for Patients With Adhesive Capsulitis of the Shoulder: A PRIMSA Systematic Review and Meta-Analysis of Randomized Controlled Trials

Abstract To compare the effect of steroid injection and physiotherapy for patients with adhesive capsulitis of the shoulder (ACS). An electronic search was performed on Pubmed, Embase, and Cochrane library, and reference lists were also reviewed for randomized controlled trials (RCTs) comparing steroid injection and physiotherapy for patients with ACS. The quality of included studies were assessed using PEDro scale. Standardized mean differences (SMDs) and 95% confidence interval (CI) were used for comparisons. The primary outcome was functional improvement. Nine RCTs including 453 patients were identified. From 6–7 weeks to 24–26 weeks postintervention, no superiority was noted in favor of either steroid injection or physiotherapy for functional improvement (SMD 0.28; 95% CI −0.01–0.58; P = 0.06) or pain relief (SMD −0.10; 95% CI −0.70–0.50; P = 0.75). Steroid injection provided more improvement in passive external rotation at 24 to 26 weeks (3 studies, SMD 0.42; 95% CI 0.11–0.72; P = 0.007) but not at 6 to 7 weeks (4 studies, SMD 0.63; 95% CI 0.36–0.89; P = 0.32) or 12 to 16 weeks (3 studies, SMD −0.07; 95% CI −0.79–0.65; P = 0.85). Steroid injection was as safe as physiotherapy for patients with ACS (risk ratio 0.94; 95% CI 0.67–1.31). Both steroid injection and physiotherapy are equally effective for patients with ACS. One steroid injection might be the 1st choice for ACS. Results should be interpreted with caution due to the heterogeneity among the studies.

A Randomized Clinical Trial to Evaluate Attached Hamstring Anterior Cruciate Ligament Graft Maturity With Magnetic Resonance Imaging

Background: The hamstring tendons are commonly harvested for anterior cruciate ligament (ACL) reconstruction with detachment of the tibial insertion. Retaining the insertion may help to preserve vascularity and viability of the graft and bypass the stages of avascular necrosis and revascularization, which might be beneficial to graft maturity. Purpose: To investigate and compare graft maturity by magnetic resonance imaging (MRI) after ACL reconstruction with preservation or detachment of hamstring tendon tibial insertion at up to 2 years. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: Forty-five patients (age range, 18-45 years) undergoing isolated ACL reconstruction with hamstring tendon were enrolled and randomized to 2 groups. The tibial insertion of the hamstring tendon was preserved in the study group (n = 21) and detached in the control group (n = 24). Patients had follow-up at 3, 6, 12, and 24 months, which consisted of the following: (1) clinical examination and (2) MRI evaluation of graft signal intensity based on signal/noise quotient (SNQ) values. Finally, 18 patients in the study group and 19 in the control group received full follow-up evaluation (ie, at all 4 time points). Results: All knees acquired full range of motion at 24 months without significant laxity. At each time point, the KT-1000 arthrometer revealed no significant difference between groups; the clinical scores significantly improved in both groups, although the difference between groups was not significant. In the control group, the SNQ value increased from 3 months, peaked at 6 months, and then decreased (3 months, 21.4 ± 12.7; 6 months, 25.6 ± 12; 12 months, 18.3 ± 7.7; 24 months, 15.3 ± 6.3). However, the insertion-preserved graft in the study group maintained relatively lower and unchanged signal intensity throughout all time points (3 months, 15.0 ± 11.2; 6 months, 14.9 ± 6.3; 12 months, 12.6 ± 7.0; 24 months, 14.6 ± 7.0). Between groups, there was no significant difference at 3 or 24 months (P = .11 and .75, respectively), while the SNQ values were significantly lower in the study group versus the control group at 6 and 12 months (P = .002 and .02, respectively). Conclusion: The insertion-detached hamstring tendon grafts underwent a significantly increasing change in signal intensity during the first 2 years after ACL reconstruction, while the insertion-preserved grafts kept a relatively lower and unchanged signal intensity. The difference was most significant at 6 and 12 months postoperatively.

A synthetic bridging patch of modified co-electrospun dual nano-scaffolds for massive rotator cuff tear

Massive rotator cuff tears (MRCTs) are difficult to repair because of the retraction and poor mobility of torn tendons. In the current study, co-electrospun dual nano-scaffolds of poly(lactic-co-glycolic acid)/collagen I-polycaprolactone/nanohydroxyapatite (PLGA/Col-PCL/nHA) were fabricated and used to bridge MRCTs of infraspinatus tendons in a rabbit model. PLGA-PCL served as a control. The PLGA or the PLGA/Col sides of the dual scaffolds connected the tendon stumps. The PCL or PCL/nHA side was inserted into the bone tunnel at the insertion of the infraspinatus tendon. Fibroblasts showed higher viability and collagen secretion when seeded on a PLGA/Col scaffold compared to a PLGA scaffold. Osteoblasts seeded on a PCL/nHA scaffold grew better with higher mineralization than on a PCL scaffold. Histologically, collagen regenerated along PLGA scaffolds, but showed poor ingrowth to scaffolds compared with the PLGA/Col group. Newly formed bone was observed on the PCL scaffold, but was less than that on the PCL/nHA scaffold. At 6 weeks post repair, the regenerated tendon in both groups had similar maximum load to failure and ultimate stress but significantly lower stiffness in the PLGA-PCL group and a higher cross-sectional area in the PLGA/Col-PCL/nHA group compared with normal values. At 12 weeks, the maximum failure load, ultimate stress and cross-sectional areas of the regenerated tendon in the PLGA/Col-PCL/nHA group were significantly higher than in the PLGA-PCL and normal groups. The biomechanical properties of the PLGA-PCL group were similar to normal except for a larger cross-sectional area. Our data showed that the co-electrospun dual nano-scaffolds are promising in bridging MRCTs. Doping with Col and nHA further strengthens tissue regeneration.

miR-24 and miR-122 Negatively Regulate the Transforming Growth Factor-β/Smad Signaling Pathway in Skeletal Muscle Fibrosis

Fibrosis is common after skeletal muscle injury, undermining tissue regeneration and function. The mechanism underlying skeletal muscle fibrosis remains unveiled. Transforming growth factor-β/Smad signaling pathway is supposed to play a pivotal role. However, how microRNAs interact with transforming growth factor-β/Smad-related muscle fibrosis remains unclear. We showed that microRNA (miR)-24-3p and miR-122-5p declined in skeletal muscle fibrosis, which was a consequence of transforming growth factor-β. Upregulating Smad4 suppressed two microRNAs, whereas inhibiting Smad4 elevated microRNAs. Luciferase reporter assay and chromatin immunoprecipitation confirmed that Smad4 directly inhibited two microRNAs. On the other hand, overexpression of these two miRs retarded fibrotic process. We further identified that Smad2 was a direct target of miR-24-3p, whereas miR-122-5p targeted transforming growth factor-β receptor-II. Both targets were important participants in transforming growth factor-β/Smad signaling. Taken together, a positive feedback loop in transforming growth factor-β/Smad4 signaling pathway in skeletal muscle fibrosis was identified. Transforming growth factor-β/Smad axis could be downregulated by microRNAs. This effect, however, was suppressed by Smad4, the downstream of transforming growth factor-β.

Silk fibroin and hydroxyapatite segmented coating enhances graft ligamentization and osseointegration processes of the polyethylene terephthalate artificial ligament in vitro and in vivo

The inferior biocompatibility of the polyethylene terephthalate (PET) artificial ligament may lead to poor healing in both the intra-articular part (IAP) and the intraosseous part (IOP) after anterior cruciate ligament (ACL) reconstruction. This study aimed to systematically investigate the effect of silk fibroin (SF) and hydroxyapatite (HA) segmented coating on graft ligamentization and osseointegration processes of the PET ligament. Several techniques including scanning electron microscopy (SEM) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD) and water contact angle (WCA) measurements were carried out to validate the introduction of SF and HA. The segmented coating ligament was assessed both in vitro and in vivo. The results of SEM and cell counting kit-8 (CCK-8) assay revealed that the L929 fibroblasts and MC3T3-E1 osteoblasts exhibited better adhesion and proliferation performance on the PET-SF and PET-HA fibers, respectively, compared to those on the uncoated PET fibers. HA promoted osteogenic differentiation of MC3T3-E1 in terms of the levels of alkaline phosphatase (ALP) activity and calcium deposition. Furthermore, the in vivo study in a beagle ACL reconstruction model demonstrated that the segmented coating could enhance the graft ligamentization and osseointegration processes as indicated by the better tissue infiltration in the IAP and more bone ingrowth in the IOP of the ligament than the control group according to the results of micro-computed tomography (micro-CT), histology, real-time polymerase chain reactions (RT-PCRs) and biomechanical tests. Therefore, the SF and HA segmented coating ligaments may display a great potential application for the clinical augmentation of graft healing in ACL reconstruction surgery.