Hyaluronic Acid Accelerates Tendon-to-Bone Healing After Rotator Cuff Repair

Hyaluronic acid/PEO electrospun tube reduces tendon adhesion to levels comparable to native tendons - An in vitro and in vivo study

A major problem after tendon injury is adhesion formation to the surrounding tissue leading to a limited range of motion. A viable strategy to reduce adhesion extent is the use of physical barriers that limit the contact between the tendon and the adjacent tissue. The purpose of this study was to fabricate an electrospun bilayered tube of hyaluronic acid/polyethylene oxide (HA/PEO) and biodegradable DegraPol® (DP) to improve the anti-adhesive effect of the implant in a rabbit Achilles tendon full laceration model compared to a pure DP tube. Additionally, the attachment of rabbit tenocytes on pure DP and HA/PEO containing scaffolds was tested and Scanning Electron Microscopy, Fourier-transform Infrared Spectroscopy, Differential Scanning Calorimetry, Water Contact Angle measurements, and testing of mechanical properties were used to characterize the scaffolds. In vivo assessment after three weeks showed that the implant containing a second HA/PEO layer significantly reduced adhesion extent reaching levels comparable to native tendons, compared with a pure DP implant that reduced adhesion formation only by 20 %. Tenocytes were able to attach to and migrate into every scaffold, but cell number was reduced over two weeks. Implants containing HA/PEO showed better mechanical properties than pure DP tubes and with the ability to entirely reduce adhesion extent makes this implant a promising candidate for clinical application in tendon repair.

Recombinant Human Parathyroid Hormone Biocomposite Promotes Bone-to-Tendon Interface Healing by Enhancing Tenogenesis, Chondrogenesis, and Osteogenesis in a Rabbit Model of Chronic Rotator Cuff Tears

PURPOSE

To investigate the effect of recombinant human parathyroid hormone (rhPTH) biocomposite on bone-to-tendon interface (BTI) healing for surgical repair of a chronic rotator cuff tear (RCT) model of rabbit, focusing on genetic, histologic, biomechanical and micro-computed tomography (CT) evaluations.

METHODS

Sixty-four rabbits were equally assigned to the 4 groups: saline injection (group A), nanofiber sheet alone (group B), rhPTH-soaked nanofiber sheet (nanofiber sheet was soaked with rhPTH, group C), and rhPTH biocomposite (rhPTH permeated the nanofiber sheet by coaxial electrospinning, group D). The release kinetics of rhPTH (groups C and D) was examined for 6 weeks in vitro. Nanofiber scaffolds were implanted on the surface of the repair site 6 weeks after the induction of chronic RCT. Genetic and histologic analyses were conducted 4 weeks after surgery. Furthermore, genetic, histologic, biomechanical, micro-CT, and serologic analyses were performed 12 weeks after surgery.

RESULTS

In vivo, group D showed the highest collagen type I alpha 1 (COL1A1), collagen type III alpha 1 (COL3A1), and bone morphogenetic protein 2 (BMP-2) messenger RNA (mRNA) expression levels (all P < .001) 4 weeks after surgery; however, there were no differences between groups at 12 weeks postsurgery. After 12 weeks postsurgery, group D showed better collagen fiber continuity and orientation, denser collagen fibers, more mature bone-to-tendon junction, and greater fibrocartilage layer formation compared with the other groups (all P < .05). Furthermore, group D showed the highest load-to-failure rate (28.9 ± 2.0 N/kg for group A, 30.1 ± 3.3 N/kg for group B, 39.7 ± 2.7 N/kg for group C, and 48.2 ± 4.5 N/kg for group D, P < .001) and micro-CT outcomes, including bone and tissue mineral density, and bone volume/total volume rate (all P < .001) at 12 weeks postsurgery.

CONCLUSIONS

In comparison to rhPTH-soaked nanofiber sheet and the other control groups, rhPTH biocomposite effectively accelerated BTI healing by enhancing the mRNA expression levels of COL1A1, COL3A1, and BMP-2 at an early stage and achieving tenogenesis, chondrogenesis, and osteogenesis at 12 weeks after surgical repair of a chronic RCT model of rabbit.

CLINICAL RELEVANCE

The present study might be a transitional study to demonstrate the efficacy of rhPTH biocomposites on BTI healing for surgical repair of chronic RCTs as an adaptable polymer biomaterial in humans.

Effects of adipose-derived cell supplementation on tendon-bone healing in a rat model of chronic rotator cuff tear with suprascapular nerve injury

OBJECTIVE

To investigate the effect of adipose-derived cells (ADCs) on tendon-bone healing in a rat model of chronic rotator cuff tear (RCT) with suprascapular nerve (SN) injury.

METHODS

Adult rats underwent right shoulder surgery whereby the supraspinatus was detached, and SN injury was induced. ADCs were cultured from the animals' abdominal fat. At 6 weeks post-surgery, the animals underwent surgical tendon repair; the ADC (+ve) group (n = 18) received an ADC injection, and the ADC (-ve) group (n = 18) received a saline injection. Shoulders were harvested at 10, 14, and 18 weeks and underwent histological, fluorescent, and biomechanical analyses.

RESULTS

In the ADC (+ve) group, a firm enthesis, including dense mature fibrocartilage and well-aligned cells, were observed in the bone-tendon junction and fatty infiltration was less than in the ADC (-ve) group. Mean maximum stress and linear stiffness was greater in the ADC (+ve) compared with the ADC (-ve) group at 18 weeks.

CONCLUSION

ADC supplementation showed a positive effect on tendon-bone healing in a rat model of chronic RCT with accompanying SN injury. Therefore, ADC injection may possibly accelerate recovery in massive RCT injuries.

Non-collagenous proteins, rather than the collagens, are key biochemical factors that mediate tenogenic bioactivity of tendon extracellular matrix

Despite the growing clinical use of extracellular matrix (ECM)-based biomaterials for tendon repair, undesired healing outcomes or complications have frequently been reported. A major scientific challenge has been the limited understanding of their functional compositions and mechanisms of action due to the complex nature of tendon ECM. Previously, we have reported a soluble ECM fraction from bovine tendons (tECM) by urea extraction, which exhibited strong, pro-tenogenic bioactivity on human adipose-derived stem cells (hASCs). In this study, to advance our previous findings and gain insights into the biochemical nature of its pro-tenogenesis activity, tECM was fractionated using (i) an enzymatic digestion approach (pepsin, hyaluronidase, and chondroitinase) to yield various enzyme-digested tECM fractions; and (ii) a gelation-based approach to yield collagen matrix-enriched (CM) and non-collagenous matrix-enriched (NCM) fractions. Their tenogenic bioactivity on hASCs was assessed. Our results collectively indicated that non-collagenous tECM proteins, rather than collagens, are likely the important biochemical factors responsible for tECM pro-tenogenesis bioactivity. Mechanistically, RNA-seq analysis revealed that tECM and its non-collagenous portion induced similar transcriptional profiles of hASCs, particularly genes associated with cell proliferation, collagen synthesis, and tenogenic differentiation, which were distinct from transcriptome induced by its collagenous portion. From an application perspective, the enhanced solubility of the non-collagenous tECM, compared to tECM, should facilitate its combination with various water-soluble biomaterials for tissue engineering protocols. Our work provides insight into the molecular characterization of native tendon ECM, which will help to effectively translate their functional components into the design of well-defined, ECM biomaterials for tendon regeneration. STATEMENT OF SIGNIFICANCE: Significant progress has been made in extracellular matrix (ECM)-based biomaterials for tendon repair. However, their effectiveness remains debated, with conflicting research and clinical findings. Understanding the functional composition and mechanisms of action of ECM is crucial for developing safe and effective bioengineered scaffolds. Expanding on our previous work with bovine tendon ECM extracts (tECM) exhibiting strong pro-tenogenesis activity, we fractionated tECM to evaluate its bioactive moieties. Our findings indicate that the non-collagenous matrix within tECM, rather than the collagenous portions, plays a major role in the pro-tenogenesis bioactivity on human adipose-derived stem cells. These insights will drive further optimization of ECM-based biomaterials, including our advanced method for preparing highly soluble, non-collagenous matrix-enriched tendon ECM for effective tendon repair.

SOX family transcription factors as therapeutic targets in wound healing: A comprehensive review

The SOX family plays a vital role in determining the fate of cells and has garnered attention in the fields of cancer research and regenerative medicine. It also shows promise in the study of wound healing, as it actively participates in the healing processes of various tissues such as skin, fractures, tendons, and the cornea. However, our understanding of the mechanisms behind the SOX family's involvement in wound healing is limited compared to its role in cancer. Gaining insight into its role, distribution, interaction with other factors, and modifications in traumatized tissues could provide valuable new knowledge about wound healing. Based on current research, SOX2, SOX7, and SOX9 are the most promising members of the SOX family for future interventions in wound healing. SOX2 and SOX9 promote the renewal of cells, while SOX7 enhances the microvascular environment. The SOX family holds significant potential for advancing wound healing research. This article provides a comprehensive review of the latest research advancements and therapeutic tools related to the SOX family in wound healing, as well as the potential benefits and challenges of targeting the SOX family for wound treatment.

Macroporous Granular Hydrogels Functionalized with Aligned Architecture and Small Extracellular Vesicles Stimulate Osteoporotic Tendon-To-Bone Healing

Osteoporotic tendon-to-bone healing (TBH) after rotator cuff repair (RCR) is a significant orthopedic challenge. Considering the aligned architecture of the tendon, inflammatory microenvironment at the injury site, and the need for endogenous cell/tissue infiltration, there is an imminent need for an ideal scaffold to promote TBH that has aligned architecture, ability to modulate inflammation, and macroporous structure. Herein, a novel macroporous hydrogel comprising sodium alginate/hyaluronic acid/small extracellular vesicles from adipose-derived stem cells (sEVs) (MHA-sEVs) with aligned architecture and immunomodulatory ability is fabricated. When implanted subcutaneously, MHA-sEVs significantly improve cell infiltration and tissue integration through its macroporous structure. When applied to the osteoporotic RCR model, MHA-sEVs promote TBH by improving tendon repair through macroporous aligned architecture while enhancing bone regeneration by modulating inflammation. Notably, the biomechanical strength of MHA-sEVs is approximately two times higher than the control group, indicating great potential in reducing postoperative retear rates. Further cell-hydrogel interaction studies reveal that the alignment of microfiber gels in MHA-sEVs induces tenogenic differentiation of tendon-derived stem cells, while sEVs improve mitochondrial dysfunction in M1 macrophages (Mφ) and inhibit Mφ polarization toward M1 via nuclear factor-kappaB (NF-κb) signaling pathway. Taken together, MHA-sEVs provide a promising strategy for future clinical application in promoting osteoporotic TBH.

The Effect of Combining Hyaluronic Acid and Human Dermal Fibroblasts on Tendon Healing

BACKGROUND

The incidence of rotator cuff tears is rapidly increasing, and operative techniques for rotator cuff repair have been developed. However, the rates of postoperative retear remain high.

PURPOSE/HYPOTHESIS

The purpose was to determine the effects of human dermal fibroblasts (HDFs) with hyaluronic acid (HA) on tendon-to-bone healing in a rabbit model of chronic rotator cuff tear injury. It was hypothesized that HA would enhance HDF proliferation and that a combination of HA and HDFs would produce a synergistic effect on the healing of repaired rotator cuff tendons of rabbits.

STUDY DESIGN

Controlled laboratory study.

METHODS

For in vitro study, HDFs were plated on a 24-well plate. After 1 day, 2 wells were designated as the test group and treated with 0.75% HA in phenol red-free Dulbecco's modified Eagle medium (DMEM). An other 2 wells served as control groups and were treated with the same volume of phenol red-free DMEM without HA. Each group was duplicated, resulting in a total of 4 wells, with 2 wells in each group for replication purposes. The cells were incubated for 24 hours, followed by 72-hour cultivation. Absorbance ratios at 96 and 24 hours were compared to evaluate cell proliferation. For the in vivo study, a total of 24 rabbits were randomly allocated to groups A, B, and C (n = 8 each). Supraspinatus tendons were detached bilaterally and left for 6 weeks to establish a chronic rotator tear model. Torn tendons were subsequently repaired using the following injections: group A, 0.5 × 106 HDFs with HA; group B, HA only; and group C, saline only. At 12 weeks after repair, biomechanical tests and histological evaluation were performed.

RESULTS

In vitro study showed that HDF proliferation significantly increased with HA (HDFs with HA vs HDFs without HA; 3.96 ± 0.09 vs 2.53 ± 0.15; P < .01). In vivo, group A showed significantly higher load-to-failure values than the other groups (53.8 ± 6.9 N/kg for group A, 30.6 ± 6.4 N/kg for group B, and 24.3 ± 7.6 N/kg for group C; P < .001). Histological evaluation confirmed that group A showed higher collagen fiber density and better collagen fiber continuity, tendon-to-bone interface maturation, and nuclear shape than the other groups (all P < .05).

CONCLUSION

This controlled laboratory study verified the potential of the combination of HDFs and HA in enhancing healing in a chronic rotator cuff tear rabbit model.

CLINICAL RELEVANCE

A potential synergistic effect on rotator cuff tendon healing may be expected from a combination of HDFs and HA.

Cocktail-like gradient gelatin/hyaluronic acid bioimplant for enhancing tendon-bone healing in fatty-infiltrated rotator cuff injury models

The regeneration of enthesis tissue (native tendon-bone interface) at the post-surgically repaired rotator cuff remains a challenge for clinicians, especially with the emergence of degenerative affection such as fatty infiltration that exacerbate poor tendon-bone healing. In this study, we proposed a cocktail-like hydrogel with a four-layer structure (BMSCs+gNC@GH) for enhancing fatty infiltrated tendon-bone healing. As collagen and hyaluronic acid are the main biomacromolecules that constitute the extracellular matrix of enthesis tissue, this hydrogel was composed of UV-curable gelatin/hyaluronic acid (GelMA/HAMA) dual network gel (GH) with nanoclay (NC) and stem cells loaded. The results showed that NC exhibited a cocktail-like gradient distribution in GH, which effectively mimicked the structure of native enthesis and supported the long-term culture and encapsulation of BMSCs. What's more, the gradient variation of NC provided a biological signal for promoting gradient osteogenic differentiation of cells. Based on the in vivo results, BMSCs+gNC@GH effectively promoted fibrocartilage layer regeneration at the tendon-bone interface and inhibited fatty infiltration. Therefore, BMSCs+gNC@GH group exhibited better biomechanical properties. Thus, this cocktail-like implant may be a promising tissue-engineered scaffold for tendon-bone healing, and it provides a new idea for the development of scaffolds with the function of inhibiting degeneration.

Transcriptional time course after rotator cuff repair in 6 month old female rabbits

Introduction: Rotator cuff tears are prevalent in the population above the age of 60. The disease progression leads to muscle atrophy, fibrosis, and fatty infiltration, which is not improved upon with surgical repair, highlighting the need to better understand the underlying biology impairing more favorable outcomes. Methods: In this study, we collected supraspinatus muscle tissue from 6 month old female rabbits who had undergone unilateral tenotomy for 8 weeks at 1, 2, 4, or 8 weeks post-repair (n = 4/group). RNA sequencing and enrichment analyses were performed to identify a transcriptional timeline of rotator cuff muscle adaptations and related morphological sequelae. Results: There were differentially expressed (DE) genes at 1 (819 up/210 down), 2 (776/120), and 4 (63/27) weeks post-repair, with none at 8 week post-repair. Of the time points with DE genes, there were 1092 unique DE genes and 442 shared genes, highlighting that there are changing processes in the muscle at each time point. Broadly, 1-week post-repair differentially expressed genes were significantly enriched in pathways of metabolism and energetic activity, binding, and regulation. Many were also significantly enriched at 2 weeks, with the addition of NIF/NF-kappaB signaling, transcription in response to hypoxia, and mRNA stability alongside many additional pathways. There was also a shift in transcriptional activity at 4 weeks post-repair with significantly enriched pathways for lipids, hormones, apoptosis, and cytokine activity, despite an overall decrease in the number of differentially expressed genes. At 8 weeks post-repair there were no DE genes when compared to control. These transcriptional profiles were correlated with the histological findings of increased fat, degeneration, and fibrosis. Specifically, correlated gene sets were enriched for fatty acid metabolism, TGF-B-related, and other pathways. Discussion: This study identifies the timeline of transcriptional changes in muscle after RC repair, which by itself, does not induce a growth/regenerative response as desired. Instead, it is predominately related to metabolism/energetics changes at 1 week post-repair, unclear or asynchronous transcriptional diversity at 2 weeks post-repair, increased adipogenesis at 4 weeks post-repair, and a low transcriptional steady state or a dysregulated stress response at 8 weeks post-repair.

TGF-β1 derived from macrophages contributes to load-induced tendon-bone healing in the murine rotator cuff repair model by promoting chondrogenesis

It has been established that mechanical stimulation benefits tendon-bone (T-B) healing, and macrophage phenotype can be regulated by mechanical cues; moreover, the interaction between macrophages and mesenchymal stem cells (MSCs) plays a fundamental role in tissue repair. This study aimed to investigate the role of macrophage-mediated MSC chondrogenesis in load-induced T-B healing in depth. C57BL/6 mice rotator cuff (RC) repair model was established to explore the effects of mechanical stimulation on macrophage polarization, transforming growth factor (TGF)-β1 generation, and MSC chondrogenesis within T-B enthesis by immunofluorescence and enzyme-linked immunosorbent assay (ELISA). Macrophage depletion was performed by clodronate liposomes, and T-B healing quality was evaluated by histology and biomechanics. In vitro, bone marrow-derived macrophages (BMDMs) were stretched with CELLOAD-300 load system and macrophage polarization was identified by flow cytometry and quantitative real-time polymerase chain reaction (qRT-PCR). MSC chondrogenic differentiation was measured by histochemical analysis and qRT-PCR. ELISA and qRT-PCR were performed to screen the candidate molecules that mediated the pro-chondrogenic function of mechanical stimulated BMDMs. Mechanical stimulation promoted macrophage M2 polarization in vivo and in vitro. The conditioned media from mechanically stimulated BMDMs (MS-CM) enhanced MSC chondrogenic differentiation, and mechanically stimulated BMDMs generated more TGF-β1. Further, neutralizing TGF-β1 in MS-CM can attenuate its pro-chondrogenic effect. In vivo, mechanical stimulation promoted TGF-β1 generation, MSC chondrogenesis, and T-B healing, which were abolished following macrophage depletion. Macrophages subjected to appropriate mechanical stimulation could polarize toward the M2 phenotype and secrete TGF-β1 to promote MSC chondrogenesis, which subsequently augments T-B healing.

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.

Evidence for Utilization of Injectable Biologic Augmentation in Primary Rotator Cuff Repair: A Systematic Review of Data From 2010 to 2022

Background

Biologic healing after rotator cuff repair remains a significant challenge. Injectable biologic augmentation may improve tissue quality at the suture-tendon interface.

Purpose

To investigate the effect of injectable biologic supplementation in rotator cuff repair and to assess the quality and adherence to evolving reporting standards.

Study Design

Systematic review; Level of evidence, 3.

Methods

A systematic review was conducted following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Included were 40 studies: 29 preclinical (in vivo animal models) and 11 clinical. Each clinical study was assessed for quality, risk of bias, and adherence to relevant MIBO (Minimum Information for Studies Evaluating Biologics in Orthopaedics) guidelines. The outcomes of interest were reported load to failure, load to gap, gap size, and stiffness in the preclinical studies, and healing rate and any patient-reported outcome measures in the clinical studies.

Results

Injectables reported included growth factors (eg, transforming growth factor-beta 3, erythropoietin), bone marrow-derived mesenchymal stem cells and adipose-derived mesenchymal stem cells (ADSCs), and other agents such as platelet-rich plasma (PRP) and hyaluronic acid. The most common findings for preclinical injectables were increased load to failure (16/29 studies; 55.2%) and improved collagen histological quality (11/29 studies; 37.9%). All 11 clinical studies (10 PRP, 1 ADSC) indicated no adverse events, with similar or improved patient-reported outcomes compared with repairs in the control groups. In 1 study utilizing an innovative delivery technique, a concentrated PRP globule with fibrin matrix was shuttled over a suture to maintain concentrated PRP at the repair site and demonstrated a significant decrease in retears (P = .03) at a 31-month follow-up. A matched-cohort study investigating augmentation with ADSCs demonstrated a significantly lower retear rate in the ADSC-augmented group than the control group at a 28-month follow-up (P < .001). On average, the clinical studies adhered to 66% of relevant MIBO reporting guidelines and had a low risk of bias.

Conclusion

Approximately 83% of preclinical studies found a positive biomechanical or histological effect, with no studies showing an overall negative effect. Clinically, utilization of innovative delivery techniques may reduce the risk of arthroscopic washout of PRP and improve retear rates. ADSCs were shown to reduce retear rates at a 28-month follow-up.

TGF-β1 stimulated mesenchymal stem cells-generated exosomal miR-29a promotes the proliferation, migration and fibrogenesis of tenocytes by targeting FABP3

BACKGROUND

Rotator cuff Tear (RCT) causes a lot of inconvenience for patients. In most cases, RCT injury does not heal back to bone after repair, and there is a high chance of retearing. Therefore, there is a need to explore more effective targeted therapies. Bone mesenchymal stem cell-derived exosome (BMSCs-Exo) has been proved to be beneficial to the proliferation of tendon cells, but its specific mechanism remains to be further explored.

METHODS

BMSCs-Exo was isolated and identified by detecting the specific markers using flow cytometry and western blot assays. qRT-PCR and western blot were utilized to determine the gene or protein expressions, respectively. Cell proliferation, and migration in tenocytes were measured by CCK8, EdU and transwell assays. The interaction between miR-29a and FABP3 was analyzed using dual-luciferase reporter assay.

RESULTS

Our findings demonstrated that miR-29a was expressed in BMSCs-Exo and could be significantly enriched after TGF-β1 treatment. Moreover, TGF-β1-modified BMSCs-Exo co-cultured could promote the proliferation, migration and fibrosis of tenocytes by carrying miR-29a. Upon miR-29a was reduced in BMSCs-Exo, the regulatory roles of BMSCs-Exo on tenocytes were reversed. Mechanistically, miR-29a negatively regulated FABP3 via interaction with its 3'-UTR. Enforced expression of FABP3 could reverse the modulation of exosomal miR-29a in tenocytes.

CONCLUSION

Exosomal miR-29a derived from TGF-β1-modified BMSCs facilitated the proliferation, migration and fibrosis of tenocytes through targeting FABP3.

Strategies for promoting tendon-bone healing: Current status and prospects

Tendon-bone insertion (TBI) injuries are common, primarily involving the rotator cuff (RC) and anterior cruciate ligament (ACL). At present, repair surgery and reconstructive surgery are the main treatments, and the main factor determining the curative effect of surgery is postoperative tendon-bone healing, which requires the stable combination of the transplanted tendon and the bone tunnel to ensure the stability of the joint. Fibrocartilage and bone formation are the main physiological processes in the bone marrow tract. Therefore, therapeutic measures conducive to these processes are likely to be applied clinically to promote tendon-bone healing. In recent years, biomaterials and compounds, stem cells, cell factors, platelet-rich plasma, exosomes, physical therapy, and other technologies have been widely used in the study of promoting tendon-bone healing. This review provides a comprehensive summary of strategies used to promote tendon-bone healing and analyses relevant preclinical and clinical studies. The potential application value of these strategies in promoting tendon-bone healing was also discussed.

Subacromial Injections of Low- or High-Molecular-Weight Hyaluronate Versus Physical Therapy for Shoulder Tendinopathy: A Randomized Triple-Blind Controlled Trial

OBJECTIVE

Shoulder tendinopathy is a prevalent and debilitating problem. We compared the effects of subacromial high- or low-molecular-weight hyaluronate injection with physical therapy (PT) in shoulder tendinopathy.

DESIGN

A triple-blinded randomized controlled trial.

SETTING

We conducted the trial in an outpatient clinic at a teaching hospital.

PARTICIPANTS

In total, 79 patients with shoulder tendinopathy were randomly allocated to high- (n = 27) or low-molecular-weight (n = 28) hyaluronate or PT (n = 24) groups.

INTERVENTIONS

We administered a 20-mg injection of high- or low-molecular-weight hyaluronate. For PT, we prescribed 10 sessions of physiotherapy and exercise.

OUTCOME MEASURES

The primary outcome was shoulder pain and the secondary outcomes included Disability of the Arm Shoulder and Hand score, shoulder range of movement and QoL. We measured the outcomes at baseline, 1, and 3 months of treatment, and assessed shoulder pain at the sixth month postintervention.

RESULTS

The interventions were all clinically beneficial in the management of tendinopathy for high- (n = 25) and low-molecular-weight (n = 24) hyaluronate and PT (n = 19) groups (all P < 0.05). However, between-group analyses indicated that hyaluronate preparations were more effective in controlling pain, decreasing disability, increasing range of motion, and improving the quality of life (all P < 0.05). The pain and subjective feeling of rigidity at the injection area ( P = 0.012) were less prominent for low-molecular-weight hyaluronate.

CONCLUSION

High- or low-molecular-weight hyaluronate is more effective than PT in the treatment of shoulder tendinopathy. The clinical benefits of hyaluronate last for at least 3 months, and the pain alleviation sustains partially for 6 months. Shoulder injection of low-molecular-weight hyaluronate is more tolerable to the patient than high-molecular-weight hyaluronate.

Three-dimensionally printed recombinant human parathyroid hormone-soaked nanofiber sheet accelerates tendon-to-bone healing in a rabbit model of chronic rotator cuff tear

BACKGROUND

Recombinant human parathyroid hormone (rhPTH) promotes tendon-to-bone healing in humans and animals with rotator cuff tear (RCT). However, problems regarding repeated systemic rhPTH injections in humans exist. This study was conducted to evaluate the effect of topical rhPTH administration using 3-dimensionally (3D) printed nanofiber sheets on tendon-to-bone healing in a rabbit RCT model compared to that of direct topical rhPTH administration.

METHODS

Eighty rabbits were randomly assigned to 5 groups (n = 16 each). To create the chronic RCT model, we induced complete supraspinatus tendon tears in both shoulders and left them untreated for 6 weeks. All transected tendons were repaired in a transosseous manner with saline injection in group A, hyaluronic acid (HA) injection in group B, 3D-printed nanofiber sheet fixation in group C, rhPTH and HA injection in group D, and 3D-printed rhPTH- and HA-soaked nanofiber sheet fixation in group E. Genetic (messenger RNA expression evaluation) and histologic evaluations (hematoxylin and eosin and Masson trichrome staining) were performed in half of the rabbits at 4 weeks postrepair. Genetic, histologic, and biomechanical evaluations (mode of tear and load to failure) were performed in the remaining rabbits at 12 weeks.

RESULTS

For genetic evaluation, group E showed a higher collagen type I alpha 1 expression level than did the other groups (P = .008) at 4 weeks. However, its expression level was downregulated, and there was no difference at 12 weeks. For histologic evaluation, group E showed greater collagen fiber continuity, denser collagen fibers, and more mature tendon-to-bone junction than did the other groups (P = .001, P = .001, and P = .003, respectively) at 12 weeks. For biomechanical evaluation, group E showed a higher load-to-failure rate than did the other groups (P < .001) at 12 weeks.

CONCLUSION

Three-dimensionally printed rhPTH-soaked nanofiber sheet fixation can promote tendon-to-bone healing of chronic RCT.

The recombinant human fibroblast growth factor-18 (sprifermin) improves tendon-to-bone healing by promoting chondrogenesis in a rat rotator cuff repair model

BACKGROUND

Rotator cuff healing is improved by reconstructing the fibrocartilaginous structure of the tendon-to-bone enthesis. Fibroblast growth factor (FGF)-18 (sprifermin) is a well-known growth factor that improves articular cartilage repair via its anabolic effect. This study aimed to investigate the effect of recombinant human FGF-18 (rhFGF-18) on the chondrogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) in vitro and tendon-to-bone healing in a rat model of rotator cuff repair.

METHODS

Histological and reverse transcription-quantitative real-time polymerase chain reaction analyses of chondral pellets cultured with different concentrations of rhFGF-18 were performed. Bilateral detachment and repair of the supraspinatus tendon were performed on rats. The rats were administered 0.2 mL of sodium alginate (SA) hydrogel with (rhFGF-18/SA group, n = 12) or without (SA group, n = 12) 20 μg of rhFGF-18 into the repaired side. The simple repair group (n = 12) served as a control. At 4 and 8 weeks after surgery, histological analysis and biomechanical tests were performed.

RESULTS

After chondrogenesis induction, compared with the control group, 10 ng/mL of rhFGF-18 increased pellet volume significantly (P = .002), with improved histological staining. It was noted that 10 ng/mL of rhFGF-18 upregulated the mRNA expression (relative ratio to control) of aggrecan (2.59 ± 0.29, P < .001), SRY-box transcription factor 9 (1.88 ± 0.05, P < .001), and type II collagen (1.46 ± 0.18, P = .009). At 4 and 8 weeks after surgery, more fibrocartilage and cartilaginous extracellular matrix was observed in rhFGF-18/SA-treated rats. The semiquantitative data from picrosirius red staining test were 31.1 ± 4.5 vs. 61.2 ± 4.1 at 4 weeks (P < .001) and 61.5 ± 2.8 vs. 80.5 ± 10.5 at 8 weeks (P = .002) (control vs. rhFGF-18/SA). Ultimate failure load (25.42 ± 3.61 N vs. 18.87 ± 2.71 N at 4 weeks and 28.63 ± 5.22 N vs. 22.15 ± 3.11 N at 8 weeks; P = .006 and P = .03, respectively) and stiffness (18.49 ± 1.38 N/mm vs. 14.48 ± 2.01 N/mm at 8 weeks, P = .01) were higher in the rhFGF-18/SA group than in the control group.

CONCLUSION

rhFGF-18 promoted chondrogenesis in the hBMSCs in vitro. rhFGF-18/SA improved tendon-to-bone healing in the rats by promoting regeneration of the fibrocartilage enthesis. rhFGF-18 (sprifermin) may be beneficial in improving tendon-to-bone healing after rotator cuff repair.

Investigação do efeito do fator de crescimento epidérmico recombinante humano na cicatrização do manguito rotador: Um modelo experimental

Objetivo Investigar a eficácia do fator de crescimento epidérmico (EGF) recombinante humano na cicatrização da lesão do manguito rotador no ombro de coelhos.

Métodos As rupturas do manguito rotador (RMRs) foram criadas experimentalmente em ambos os ombros de 20 coelhos Nova Zelândia. Os coelhos foram divididos nos seguintes grupos: RMR (grupo controle; n = 5), RMR + EGF (grupo EGF; n = 5), RMR + reparo transósseo (grupo reparo; n = 5) e RMR + EGF + reparo transósseo (grupo reparo combinado + EGF; n = 5). Todos os coelhos foram observados por 3 semanas, e amostras de biópsias foram coletadas do ombro direito na 3ª semana. Após mais 3 semanas de observação, todos os coelhos foram submetidos à eutanásia, e uma amostra de biópsia foi coletada dos ombros esquerdos. Todo o material de biópsia foi corado com hematoxilina e eosina (H&E) para avaliação de vascularidade, celularidade, proporção de fibras e número de células fibrocartilaginosas à microscopia óptica.

Resultados O grupo reparo combinado + EGF apresentou a maior quantidade e a sequência mais regular de colágeno. O grupo reparo e o grupo EGF apresentaram maior atividade fibroblástica e formação capilar em comparação ao grupo controle, mas a maior atividade fibroblástica e a formação capilar com maior vascularidade foram detectadas no grupo reparo combinado + EGF (p < 0,001). O EGF parece melhorar a cicatrização da ferida no reparo da RMR. A aplicação isolada de EGF, mesmo sem cirurgia reparadora, parece melhorar a cicatrização da RMR.

Conclusão Além do reparo da RMR, a aplicação de EGF recombinante humano auxilia a cicatrização do manguito rotador dos ombros de coelhos.

Use of a Nanofiber Resorbable Scaffold During Rotator Cuff Repair: Surgical Technique and Results After Repair of Small- to Medium-Sized Tears

Background:

The rate of retear after primary rotator cuff failure remains unacceptably high (up to 36% for small- to medium-sized tears). Augmentation of cuff repair with scaffold devices has been reported to improve healing after cuff repair.

Purpose/Hypothesis:

To describe the surgical technique of using an interpositional nanofiber scaffold during rotator cuff repair and report on a retrospective series of patients regarding functional outcomes and postoperative healing on magnetic resonance imaging (MRI). We hypothesized that augmentation of cuff repair with an interpositional scaffold would result in a high rate of tendon healing and excellent functional outcomes.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 33 patients underwent arthroscopic rotator cuff repair augmented with a nanofiber, bioresorbable polymer patch secured as an inlay between the tendon and underlying bone. Patients were evaluated preoperatively and postoperatively with the Simple Shoulder Test (SST), American Shoulder and Elbow Surgeons (ASES) shoulder score, and active range of motion (ROM) measurements. Postoperative MRI was used to evaluate repair status.

Results:

At a minimum follow-up of 6 months, the patients showed significant improvement on SST and ASES scores (P < .0001 for both). ROM in forward flexion, abduction, internal rotation, and external rotation significantly improved at 6 months postoperatively (P < .05 for all). MRI at an average of 11 months postoperatively showed healing in 91% of patients; one patient had a recurrent tear with transtendon failure, and another patient had retear at the insertional site. The patch was not visible on postoperative imaging, suggesting complete resorption in all patients. No adverse events were associated with the patch.

Conclusion:

Our results demonstrate the preliminary safety and efficacy of a novel, bioresorbable synthetic scaffold for rotator cuff repair. The use of the scaffold resulted in a 91% tendon healing rate and significant improvements in functional and patient-reported outcome measures. The results are promising for improving the current unacceptably high rate of rotator cuff repair failure.

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.

The “Second Hit” of Repair in a Rabbit Model of Chronic Rotator Cuff Tear

The rabbit supraspinatus is a useful translational model for rotator cuff (RC) repair because it recapitulates muscle atrophy and fat accumulation observed in humans after a chronic tear (the “first hit”). However, a timeline of RC tissue response after repair, especially with regard to recent evidence of muscle degeneration and lack of regeneration, is currently unavailable. Thus, the purpose of this study was to characterize the progression of muscle and fat changes over time after the repair of a chronic RC tear in the rabbit model. Two rounds of experiments were conducted in 2017–2018 and 2019–2020 with N = 18 and 16 skeletally mature New Zealand White rabbits, respectively. Animals underwent left supraspinatus tenotomy with repair 8 weeks later. The unoperated right shoulder served as control. The rabbits were sacrificed at 1-, 2-, 4-, and 8-weeks post-repair for histological and biochemical analysis. Atrophy, measured by fiber cross-sectional area and muscle mass, was greatest around 2 weeks after repair. Active muscle degeneration peaked at the same time, involving 8% of slide areas. There was no significant regeneration at any timepoint. Fat accumulation and fibrosis were significantly increased across all time points compared to contralateral. Statement of Clinical Significance: These results demonstrate model reproducibility and a “second hit” phenomenon of repair-induced muscle atrophy and degeneration which partially recovers after a short time, while increased fat and fibrosis persist.

Retracted Rotator Cuff Repairs Heal With Disorganized Fibrogenesis Without Affecting Biomechanical Properties: A Comparative Animal Model Study

PURPOSE

To determine the differences in the scar tissue formation during the healing of the repaired retracted cuff tear from that of the nonretracted tear.

METHODS

Eighteen right rabbit shoulders received a 1-cm transverse cuff incision over the footprint to simulate "nonretracted cuff tears" before the transosseous repairs (group A). A 1-cm tendinous portion was excised from 18 left shoulders to create defects to simulate "retracted cuff tears" before repairing the defects (group B). At week 12 postrepair, 20 and 16 shoulders underwent histologic and biomechanical analyses, respectively. Eight shoulders were used as a control group for biomechanical analyses.

RESULTS

All specimens showed good healing and continuity of the repaired tendons. At low magnification, fibrous tissue firmly held the tendon-to-bone junctions in group A; however, all specimens in group B showed medially retracted tendons with fibrous tissue continuity between the tendon stumps and footprints. At medium magnification, more irregular collagen fiber orientation was observed in group B. Polarized light microscopy showed fibrous tissue continuity with medially retracted tendons in group B. When we quantified collagen fiber orientation using ImageJ software, group B had inferior grayscale measurements when compared with group A (P = .001). At week 12, no statistical differences existed in mean loads-to-failure at the repair sites between the groups (P = .783).

CONCLUSIONS

In the nonretracted cuff tears, fibrous tissue bound the tendon-to-bone junction with healing. After the healing of the retracted cuff tears, continuity of nontendinous tissue was observed adjacent to the medially retracted tendon, which comprised more disorganized immature fibrous tissue than that in the nonretracted cuff tears.

CLINICAL RELEVANCE

Unlike the healing of nonretracted rotator cuff tear, repairing of the "retracted" tendon end of cuff tear still resulted in retraction of the tendon back to its original position but being held down with fibrous tissue to the footprint.

The role of tendon derived stem/progenitor cells and extracellular matrix components in the bone tendon junction repair

Fibrocartilage enthesis is the junction between bone and tendon with a typical characteristics of fibrocartilage transition zones. The regeneration of this transition zone is the bottleneck for functional restoration of bone tendon junction (BTJ). Biomimetic approaches, especially decellularized extracellular matrix (ECM) materials, are strategies which aim to mimic the components of tissues to the utmost extent, and are becoming popular in BTJ healing because of their ability not only to provide scaffolds to allow cells to attach and migrate, but also to provide a microenvironment to guide stem/progenitor cells lineage-specific differentiation. However, the cellular and molecular mechanisms of those approaches, especially the ECM proteins, remain unclear. For BTJ reconstruction, fibrocartilage regeneration is the key for good integrity of bone and tendon as well as its mechanical recovery, so the components which can guide stem cells to a chondrogenic commitment in biomimetic approaches might well be the key for fibrocartilage regeneration and eventually for the better BTJ healing. In this review, we firstly discuss the importance of cartilage-like formation in the healing process of BTJ. Next, we explore the possibility of tendon-derived stem/progenitor cells as cell sources for BTJ regeneration due to their multi-differentiation potential. Finally, we summarize the role of extracellular matrix components of BTJ in guiding stem cell fate to a chondrogenic commitment, so as to provide cues for understanding the mechanisms of lineage-specific potential of biomimetic approaches as well as to inspire researchers to incorporate unique ECM components that facilitate BTJ repair into design.

Low Molecular-weight Hyaluronic Acid Versus Physiotherapy for the Treatment of Supraspinatus Tendinopathy: A Randomized Comparative Clinical Trial

INTRODUCTION

The tendons of the rotator cuff are major sources of shoulder pain. This study aimed to compare the effects of low molecular-weight hyaluronic acid with physiotherapy (PT) in patients with supraspinatus tendinopathy (ST).

METHODS

We carried out a parallel two-group randomized comparative clinical trial in an outpatient clinic of physical medicine and rehabilitation at a teaching hospital. In total, 51 patients (31 women) aged 20 to 55 years with ST were randomly allocated to subacromial hyaluronate injection (n = 28) and PT (n = 23) groups. For the hyaluronate group, we administered a single injection of 2 mL (20 mg) hyaluronate 1% (500 to 700 kDa). For PT, we prescribed three sessions of treatment per week for 12 weeks, totaling 36 sessions including rotator cuff activation exercises. The primary outcome was shoulder pain in the visual analog scale. The secondary outcomes included the range of movement and the disability score of the shoulder, and a World Health Organization questionnaire on quality of life. We did the measurements at the baseline and at one, four, and 12 weeks after intervention.

RESULTS

The results showed that both interventions were beneficial in the management of ST. However, hyaluronate was more effective in reducing shoulder pain at rest and during activities (both P < 0.001, effect size = 0.52 and 0.68, respectively). The two interventions similarly decreased patients' disability (P = 0.196). Hyaluronate improved shoulder motion and the quality of life better than PT.

CONCLUSION

In the treatment of ST, low molecular-weight hyaluronate is more effective than PT, at least for three months. Particularly, hyaluronate is more successful in alleviating pain.

Effect of co-administration of atelocollagen and hyaluronic acid on rotator cuff healing

Background

This study aimed to evaluate the co-administration effect of atelocollagen combined with hyaluronic acid (HA) injections for treatment of full-thickness rotator cuff tear (RCT).

Methods

Eighty patients who underwent arthroscopic rotator cuff repair for full-thickness RCT from March 2018 to November 2019 were enrolled. The patients were randomly allocated to the following groups: combined atelocollagen and HA injection (group I, n=28), only HA injection (group II, n=26), and no injection (group III, n=26). Clinical outcomes were assessed at 3, 6, and 12 months after surgery using the American Shoulder and Elbow Surgeons score, visual analog scale pain score , functional scores (pain visual analog scale, function visual analog score), and range of motion. Magnetic resonance imaging was performed 12 months after surgery to evaluate rotator cuff integrity.

Results

Preoperative demographic data and postoperative clinical outcomes did not differ significantly among the three groups (p>0.05). However, in group I, the number of steroid injections after surgery was significantly lower than that in the other groups (p=0.011). The retear rate on follow-up magnetic resonance imaging was significantly higher in group II (9.5%, n=2) and group III (13.6%, n=3) than in group I (0%) (p=0.021).

Conclusions

Co-administration of atelocollagen and HA improves healing of the rotator cuff and increases the integrity of the rotator cuff repair site. This study provides encouraging evidence for use of combined atelocollagen-HA injections to treat patients with full-thickness RCT.

Comparison of the effect of hyaluronic acid injection versus extracorporeal shockwave therapy on chronic plantar fasciitis: Protocol for a randomized controlled trial

BACKGROUND

Plantar fasciitis is the most common cause of pain in the plantar region of the heel, and extracorporeal shockwave therapy (ESWT) is an option used in cases where conservative treatment fails. Hyaluronic acid (HA), initially used for osteoarthrosis, is a treatment option because it has been applied to extra-articular regions, such as tendons, ligaments, and fascia. The aim of the present study will be to evaluate the outcomes of pain, function, and personal satisfaction after a single injection of HA and to compare the results with those of ESWT in patients with chronic plantar fasciitis.

METHODS

The study will include 80 patients who will be randomized to receive three sessions of ESWT (n = 40) or a single ultrasound-guided HA injection in the plantar fascia (n = 40). The outcomes will include the visual analog pain scale score, American Orthopaedic Foot and Ankle Society (AOFAS) score, and Foot and Ankle Outcome Score (FAOS). All of the assessments will be performed at baseline and 3, 6, and 12 months after treatment. Statistical analysis will be performed using the repeated measures ANOVA (analysis of variance test) for primary and secondary outcomes and also Fisher's Least Significant Difference, a Post-Hoc test. We will use R software for statistical analysis, randomization, and sample size calculation.

RESULTS

Recruitment and data collection will begin in November 2020, with completion scheduled for November 2022 and final publication available in March 2023.

CONCLUSION

This trial will evaluate the effects of a single ultrasound-guided HA injection for the treatment of chronic plantar fasciitis.

TRIAL REGISTRATION

Brazilian Clinical Trials Registry (Register Number: RBR-97vkx4) http://www.ensaiosclinicos.gov.br/rg/RBR-97vkx4/.

Electrospun nanofibers promote wound healing: theories, techniques, and perspectives

At present, the clinical strategies for treating chronic wounds are limited, especially when it comes to pain relief and rapid wound healing. Therefore, there is an urgent need to develop alternative treatment methods. This paper provides a systematic review on recent researches on how electrospun nanofiber scaffolds promote wound healing and how the electrospinning technology has been used for fabricating multi-dimensional, multi-pore and multi-functional nanofiber scaffolds that have greatly promoted the development of wound healing dressings. First, we provide a review on the four stages of wound healing, which is followed by a discussion on the evolvement of the electrospinning technology, what is involved in electrospinning devices, and factors affecting the electrospinning process. Finally, we present the possible mechanisms of electrospun nanofibers to promote wound healing, the classification of electrospun polymers, cell infiltration favoring fiber scaffolds, antibacterial fiber scaffolds, and future multi-functional scaffolds. Although nanofiber scaffolds have made great progress as a type of multi-functional biomaterial, major challenges still remain for commercializing them in a way that fully meets the needs of patients.

High- Versus Low-Molecular-Weight Hyaluronic Acid for the Treatment of Rotator Cuff Tendinopathy: A Triple-Blind Randomized Comparative Trial

BACKGROUND

Shoulder pain most commonly originates from the tendon structures of the rotator cuff.

OBJECTIVE

We compared the clinical effects of high- versus low-molecular-weight (LMW) hyaluronic acid for the management of rotator cuff tendinopathy.

METHODS

We carried out a parallel, triple-blind, randomized comparative trial at a teaching hospital. In total, 56 patients aged 16 to 70 years with rotator cuff tendinopathy were randomly allocated to 2 groups. We administered a single shoulder injection of either 1 mL of 1% high- (>2000 kDa) or 1 mL of 1% LMW hyaluronate (500-700 kDa) to the corresponding groups. The primary outcome was the intensity of shoulder pain. The secondary outcomes were range of motion and disability of the shoulder, and quality of life. We performed the measurements at baseline and at 1, 4, and 12 weeks postintervention. The pain measurements were repeated at the sixth month postintervention.

RESULTS

Comparisons of baseline versus 3 months showed that both interventions were beneficial in the management of the tendinopathy (all P values <0.05). However, between-group analyses did not indicate any clinically significant difference between the 2 medications. The pain, induration (P = 0.007), and inflammation at the site of the injection were less prominent for LMW hyaluronate.

CONCLUSION AND RELEVANCE

Both medications are effective for the treatment of tendinopathy. The benefits last at least for 3 months, and pain alleviation lasts partially for 6 months. The shoulder injection of LMW hyaluronate is more tolerable to the patient. Therefore, we recommend LMW hyaluronate as the first choice for the management of rotator cuff tendinopathy.

Needle knife therapy plus sodium hyaluronate injection for knee osteoarthritis: A protocol for a systematic review and meta-analysis

BACKGROUND

Knee osteoarthritis (KOA) is a worldwide disease and more and more people are suffered from it. With the increasing number of patients, it brings a huge burden on social economy and security system. There are varieties of methods to cure KOA, such as Traditional Chinese Medicine and surgery. Needle knife therapy plus Sodium hyaluronate Injection is one of the prevalent treatments for KOA. Therefore, we perform a systematic review and meta-analysis to evaluate the evidence for the treatment of needle knife therapy plus sodium hyaluronate Injection.

METHODS

Randomized controlled trials will be used to compare the effect of needle knife therapy plus sodium hyaluronate injection with needle knife alone for KOA patients. Six studies will be included in this meta-analysis, and the relative risk and weight mean difference with 95% CI for the Lysholm knee score, visual analogue scale, and effective rate will be evaluated by using RevMan 5.3 software. Besides, the bias assessment of the included studies will be evaluated using the Cochrane risk of bias tool, and the Grading of Recommendations, Assessment Development, and Evaluation system will be applied to assess the overall quality of the evidence.

RESULTS

From the study we will assess the effectiveness, safety of needle knife therapy plus sodium hyaluronate injection on joint pain relief and functional improvement in patients with KOA.

CONCLUSION

The study will provide a new evidence to confirm the effect of needle knife therapy plus sodium hyaluronate injection on KOA, which can further guide the selection of therapy.

PROSPERO REGISTRATION NUMBER

CRD42020169602.

Conjugation with Methylsulfonylmethane Improves Hyaluronic Acid Anti-Inflammatory Activity in a Hydrogen Peroxide-Exposed Tenocyte Culture In Vitro Model

Rotator cuff tears (RCTs) and rotator cuff disease (RCD) are important causes of disability in middle-aged individuals affected by nontraumatic shoulder dysfunctions. Our previous studies have demonstrated that four different hyaluronic acid preparations (HAPs), including Artrosulfur^® hyaluronic acid (HA) (Alfakjn S.r.l., Garlasco, Italy), may exert a protective effect in human RCT-derived tendon cells undergoing oxidative stress damage. Recently, methylsulfonylmethane (MSM) (Barentz, Paderno Dugnano, Italy) has proven to have anti-inflammatory properties and to cause pain relief in patients affected by tendinopathies. This study aims at evaluating three preparations (Artrosulfur^® HA, MSM, and Artrosulfur^® MSM + HA) in the recovery from hydrogen peroxide-induced oxidative stress damage in human tenocyte. Cell proliferation, Lactate Dehydrogenase (LDH) release, and inducible nitric oxide synthases (iNOS) and prostaglandin E2 (PGE2) modulation were investigated. In parallel, expression of metalloproteinases 2 (MMP2) and 14 (MMP14) and collagen types I and III were also examined. Results demonstrate that Artrosulfur^® MSM + HA improves cell escape from oxidative stress by decreasing cytotoxicity and by reducing iNOS and PGE2 secretion. Furthermore, it differentially modulates MMP2 and MMP14 levels and enhances collagen III expression after 24 h, proteins globally related to rapid acceleration of the extracellular matrix (ECM) remodelling and thus tendon healing. By improving the anti-cytotoxic effect of HA, the supplementation of MSM may represent a feasible strategy to ameliorate cuff tendinopathies.

Preoperative hyaluronic acid injection modulates postoperative functional outcome in patients undergoing arthroscopic rotator cuff repair

Background

Arthroscopic rotator cuff repair (ARCR) generally yields acceptable clinical results. Hyaluronic acid (HA), a high-molecular-weight polysaccharide, is present in the extracellular matrix of soft connective tissue and synovial fluid, and its injection is known to significantly improve pain and clinical outcomes after rotator cuff injury. Some studies have described the role of HA injections as conservative therapy for rotator cuff tears. Since the subacromial bursa is believed to be the main source of shoulder pain in rotator cuff tears, subacromial injection is frequently used before surgery; however, its relationship with the clinical outcome after surgery remains unclarified. Therefore, we aimed to examine effects of preoperative subacromial HA injection on postoperative clinical outcome in patients with ARCR.

Methods

Ninety-eight patients were divided into a HA injection group and a non-injection group. The functional outcome measured was the University of California, Los Angeles (UCLA) score. Univariate analysis was performed to obtain variables with p values less than 0.1; we then used propensity score analysis, adjusting for pre- and post-operative confounding factors.

Results

The UCLA scores of all patients significantly improved 1 year postoperatively (PO) (p < 0.05). Subacromial HA injections were performed in patients with worse preoperative function. Univariate analysis showed significantly greater improvements in the injection group than in the non-injection group in terms of preoperative UCLA score, trauma, diabetes mellitus, UCLA score 3 months PO, abduction strength 4 months PO, and internal rotation (IR) strength 6 and 12 months PO. Propensity score analysis demonstrated that UCLA scores 3 months PO and IR strength 12 months PO in the injection group were significantly greater than those in the non-injection group. There were no significant differences in postoperative re-tear rates between the groups. In sub-analysis of the injection group, propensity scores showed that concurrent use of local anesthetics did not affect the data, suggesting that HA was effective.

Conclusion

Subacromial injection was administered to patients with worse function before ARCR. Propensity score analysis successfully demonstrated that functional outcome after surgery was improved in patients who were administered this injection compared with patients who were not administered this injection before surgery.

LncRNA TUG1 promoted osteogenic differentiation through promoting bFGF ubiquitination

LncRNA TUG1 has the potential to promote the osteogenic differentiation of several cells, but the role of lncRNA TUG1 in osteogenic differentiation of tendon stem/progenitor cells (TSPCs) is still unknown. This study aims to determine the role of lncRNA TUG1 in osteogenic differentiation of TSPCs. bFGF, RUNX2, and Osterix protein expressions were detected by western blot. LncRNA TUG1 and bFGF expression was detected by qRT-PCR. RNA immunoprecipitation (RIP) assay was used to confirm the interaction between TUG1 and bFGF2. Ubiquitination assay was used to determine the ubiquitination of bFGF protein. During osteogenic differentiation, the protein expression of bFGF was significantly downregulated in TSPCs, and the expression of TUG1 was significantly elevated in TSPCs. Interfering TUG1 or overexpressing bFGF suppressed osteogenic differentiation of TSPCs. In addition, lncRNA TUG1 interacted with bFGF, and lncRNA TUG1 promoted the ubiquitination of bFGF protein. We also determined that lncRNA TUG1 downregulated bFGF protein expression through promoting the ubiquitination of bFGF. LncRNA TUG1 promoted the osteogenic differentiation of TSPCs through promoting bFGF ubiquitination.

Does the Use of Injectable Atelocollagen during Arthroscopic Rotator Cuff Repair Improve Clinical and Structural Outcomes?

Background

Since the establishment of biological augmentation to improve the treatment of rotator cuff tears, it is imperative to explore newer techniques to reduce the retear rate and improve long-term shoulder function after rotator cuff repair. This study was undertaken to determine the consequences of a gel-type atelocollagen injection during arthroscopic rotator cuff repair on clinical outcomes, and evaluate its effect on structural integrity.

Methods

Between January 2014 and June 2015, 121 patients with full thickness rotator cuff tears underwent arthroscopic rotator cuff repair. Of these, 61 patients were subjected to arthroscopic rotator cuff repair in combination with an atelocollagen injection (group I), and 60 patients underwent arthroscopic rotator cuff repair alone (group II). The visual analogue scale (VAS) for pain and the Korean Shoulder Society (KSS) scores were evaluated preoperatively and postoperatively. Magnetic resonance imaging (MRI) was performed at 6 months postoperatively, to assess the integrity of the repair.

Results

VAS scores were significantly lower in group I than in group II at 3, 7, and 14 days after surgery. KSS scores showed no significant difference between groups in the 24 months period of follow-up. No significant difference was obtained in the healing rate of the rotator cuff tear at 6 months postoperatively (p=0.529).

Conclusions

Although a gel-type atelocollagen injection results in reduced pain in patients at 2 weeks after surgery, our study does not substantiate the administration of atelocollagen during rotator cuff repair to improve the clinical outcomes and healing of the rotator cuff.

MicroRNA-29a Mitigates Subacromial Bursa Fibrosis in Rotator Cuff Lesion with Shoulder Stiffness

Rotator cuff lesion with shoulder stiffness is a major cause of shoulder pain and motionlessness. Subacromial bursa fibrosis is a prominent pathological feature of the shoulder disorder. MicroRNA-29a (miR-29a) regulates fibrosis in various tissues; however, the miR-29a action to subacromial bursa fibrosis remains elusive. Here, we reveal that subacromial synovium in patients with rotator cuff tear with shoulder stiffness showed severe fibrosis, hypertrophy, and hyperangiogenesis histopathology along with significant increases in fibrotic matrices collagen (COL) 1A1, 3A1, and 4A1 and inflammatory cytokines, whereas miR-29a expression was downregulated. Supraspinatus and infraspinatus tenotomy-injured shoulders in transgenic mice overexpressing miR-29a showed mild swelling, vascularization, fibrosis, and regular gait profiles as compared to severe rotator cuff damage in wild-type mice. Treatment with miR-29a precursor compromised COL3A1 production and hypervascularization in injured shoulders. In vitro, gain of miR-29a function attenuated COL3A1 expression through binding to the 3’-untranslated region (3′-UTR) of COL3A1 in inflamed tenocytes, whereas silencing miR-29a increased the matrix expression. Taken together, miR-29a loss is correlated with subacromial bursa inflammation and fibrosis in rotator cuff tear with shoulder stiffness. miR-29a repressed subacromial bursa fibrosis through directly targeting COL3A1 mRNA, improving rotator cuff integrity and shoulder function. Collective analysis offers a new insight into the molecular mechanism underlying rotator cuff tear with shoulder stiffness. This study also highlights the remedial potential of miR-29a precursor for alleviating the shoulder disorder.

Therapeutic potential of exosomes in rotator cuff tendon healing

Rotator cuff tears are common musculoskeletal injuries that can cause significant pain and disability. While the clinical results of rotator cuff repair can be good, failure of tendon healing remains a significant problem. Molecular mechanisms underlying structural failure following surgical repair remain unclear. Histologically, enhanced inflammation, disorganization of the collagen fibers, calcification, apoptosis and tissue necrosis affect the normal healing process. Mesenchymal stem cells (MSCs) have the ability to provide improved healing following rotator cuff repair via the release of mediators from secreted 30-100 nm extracellular vesicles called exosomes. They carry regulatory proteins, mRNA and miRNA and have the ability to increase collagen synthesis and angiogenesis through increased expression of mRNA and release of proangiogenic factors and regulatory proteins that play a major role in proper tissue remodeling and preventing extracellular matrix degradation. Various studies have shown the effect of exosomes on improving outcome of cutaneous wound healing, scar tissue formation, degenerative bone disease and Duchenne Muscular Dystrophy. In this article, we critically reviewed the potential role of exosomes in tendon regeneration and propose the novel use of exosomes alone or seeded onto biomaterial matrices to stimulate secretion of favorable cellular factors in accelerating the healing response following rotator cuff repair.

Nrf2-mediated cytoprotective effect of four different hyaluronic acids by molecular weight in human tenocytes

Non-traumatic rotator cuff tears (RCTs) are a frequent and potentially disabling injury. There is growing evidence that hyaluronic acid (HA) is effective for pain relief and to counteract inflammation in RCTs, however, its effective role in tendinopathies remains poorly studied. This study aims to disclose a possible molecular mechanism underlying the cytoprotective effects of four different HA preparations (Artrosulfur HA^®, Synolis VA^®, Hyalgan^® and Hyalubrix^®) under H₂O₂-induced oxidative stress. Expression-levels of Lactate dehydrogenase (LDH) released were quantified in cell supernatants, CD44 expression levels were analysed by fluorescence microscopy, the mitochondrial membrane depolarisation (TMRE assay) was measured by flow cytometry and the role of the transcription factor Nrf2 was investigated as a potential therapeutic target for RCT treatment. The modulation of extracellular matrix- (ECM) related protein expression (Integrin β1, pro-collagen 1A2 and collagen 1A1) and autophagy occurrence (Erk 1/2 and phosphoErk 1/2 and LC3B), were all investigated by Western Blot. Results demonstrate that Artrosulfur HA, Hyalubrix and Hyalgan improve cell escape from H₂O₂-induced oxidative stress, decreasing cytotoxicity, reducing Nrf2 expression and enhancing catalase recovery. This study lays the grounds for further investigations insight novel pharmaceutical strategies targeting key effectors involved in the molecular cascade triggered by HA.

The application of BMP-12-overexpressing mesenchymal stem cells loaded 3D-printed PLGA scaffolds in rabbit rotator cuff repair

This study investigates if the application of bone marrow-derived mesenchymal stem cells (BM-MSCs) loaded 3D-printed scaffolds could improve rotator cuff repair. The polylactic-co-glycolic acid (PLGA) scaffolds were fabricated by 3D print technology. Rabbit BM-MSCs were transfected with a recombinant adenovirus encoding bone morphogenic protein 12 (BMP-12). The effect of BM-MSCs loaded PLGA scaffolds on tendon-bone healing was assessed by biomechanical testing and histological analysis in a rabbit rotator cuff repair model. We found that the PLGA scaffolds had good biocompatible and biodegradable property. Overexpression of BMP-12 increased the mRNA and protein expression of tenogenic genes in BM-MSCs cultured with DMEM medium and seeded in PLGA scaffolds. When BMP-12-overexpressing BM-MSCs-loaded PLGA scaffolds were implanted into the injured rabbit supraspinatus tendon-bone junctions, the tendon-bone healing was improved. Our results suggest that application of BMP-12 overexpressing BM-MSCs loaded 3D-printed PLGA scaffolds promote the healing of tendon-bone interface, improve collagen organization and increase fibrocartilage in the rabbit rotor cuff repair. Rotator cuff regeneration achieved by BMP-12-overexpressing BM-MSCs-loaded PLGA scaffolds may represent a novel approach for the management of rotator cuff defect.

Sodium Hyaluronate and Platelet-Rich Plasma for Partial-Thickness Rotator Cuff Tears

Purpose

The treatment of partial-thickness rotator cuff tears (PTRCT) remains controversial. Few studies have focused on the conservative and new measurements of small to medium PTRCT. The use of sodium hyaluronate (SH) or platelet-rich plasma (PRP) as a method for rotator cuff repair requires further investigation. The aim of this study was to evaluate the combined use of SH and PRP in the treatment of small to medium PTRCT.

Study Design

A double-blinded randomized trial was used in this study.

Methods

Individuals with PTRCT detected by clinical examination and magnetic resonance imaging (MRI) were included in this study. The patients were randomly assigned to receive subacromial injections of normal saline, SH, PRP, or SH + PRP once a week for 4 wk. The primary outcome measure was the Constant score, and the secondary outcomes included the American Shoulder and Elbow Surgeons (ASES) and the visual analog scale scores. All of the clinical outcomes were assessed at pretreatment and 1, 3, 6, and 12 months posttreatment. MRI was used to evaluate the evolution of the cuff defect after 1 yr.

Results

The PRP group and the SH + PRP group showed a significantly higher Constant score and ASES score after the treatments. There were significant differences between the SH + PRP group and the SH or PRP group at 12 months in the Constant, visual analog scale, and ASES scores. MRI results showed that the tear size significantly decreased in both the PRP and the SH + PRP groups, especially in the SH + PRP group.

Conclusion

Our study provided evidence of the efficacy of PRP injection in the healing of small to medium PTRCT. Moreover, the combined injection of SH and PRP yielded a better clinical outcome than SH or PRP alone.

Enhancement of rotator cuff tendon-bone healing using bone marrow-stimulating technique along with hyaluronic acid

Objective

The purpose of this study was to investigate the effect of hyaluronic acid (HA) in the tendon–bone healing process after rotator cuff repair in a rabbit model.

Methods

In vitro, rat bone marrow stromal cells (rBMSCs) were cultured in media for cartilage-related and inflammation-related gene expression levels examination at 1.0 mg/mL of HA. In vivo, 48 New Zealand white rabbits underwent rotator cuff repair surgery, and they were randomly divided into three groups: (1) control group (n = 16), (2) microfracture (MF) group accepting MF treatment (n = 16) and (3) MF/HA group accepting MF with HA treatment (n = 16). Four rabbits from each group were sacrificed at 6 and 12 weeks postoperatively for histological evaluation and biomechanical testing.

Results

In vitro experiments reveal that HA significantly decreased inflammation-related mRNA expression (IL-1, TNFα) compared with the control group. At 6 weeks after surgery, there was no significant difference of load-to-failure between groups. At 12 weeks after surgery, the mean failure load of the MF/HA group was significantly higher than that of the control group (100.5 ± 10.1 N vs. 68.0 ± 6.2 N; p = 0.0115). The mean failure load of the MF group appeared higher than that of the control group, whereas there was no significant difference (p > 0.05). Histologically, more chondrocytes were clustered at the tendon–bone interface, and more extracellular matrixes were produced in the MF/HA group. The interface of the MF/HA group appeared similar with the normal tendon–bone interface.

Conclusion

HA may play a crucial role in the acceleration of tendon-to-bone healing which might be through inhibiting inflammation. Rotator cuff repair using MF along with HA led to better tendon–bone healing and a subsequent increase of biomechanical strength at the repair site.

The translational potential of this article

HA injection is very common for patients with rotator cuff disease because of its antiinflammatory action and adhesion prevention preoperatively. The HA injection during surgery provides an antiinflammatory effect during tendon–bone healing process and leads to better tendon–bone healing postoperatively.

Assembly, maturation, and degradation of the supraspinatus enthesis

The development of the rotator cuff enthesis is still poorly understood. The processes in the early and late developmental steps are gradually elucidated, but it is still unclear how cell activities are coordinated during development and maturation of the structured enthesis. This review summarizes current knowledge about development and age-related degradation of the supraspinatus enthesis. Healing and repair of an injured and degenerated supraspinatus enthesis also remain a challenge, as the original graded transitional tissue of the fibrocartilaginous insertion is not re-created after the tendon is surgically reattached to bone. Instead, mechanically inferior and disorganized tissue forms at the healing site because of scar tissue formation. Consequently, the enthesis never reaches mechanical properties comparable to those of the native enthesis. So far, no novel biologic healing approach has been successful in enhancing healing of the injured enthesis. The results revealed in this review imply the need for further research to pave the way for better treatment of patients with rotator cuff disorder.

The Role of Biologic Therapy in Rotator Cuff Tears and Repairs

PURPOSE OF REVIEW

The purpose of this review was to establish the foundation of the major biologic adjuvants to rotator cuff repairs and review recent scientific findings.

RECENT FINDINGS

Platelet-rich plasma (PRP) overall has no significant impact on functional outcomes and repair integrity, but may be more advantageous in small to medium tears. Further studies should focus on leukocyte-rich versus poor preparations and the use of PRP in patients that are high risk for repair failure. Biologic and synthetic patches or augments provide mechanical stability for large and massive rotator cuff tears and decrease re-tear rates. Mesenchymal stem cells have demonstrated improved healing rates without an impact on outcomes. Cytokines and growth factors show promise in animal models, but require human trials to further evaluate. In massive or revision repairs, allograft or synthetic patch augmentation should be considered. Platelet-rich plasma may have benefit in smaller tears. Further studies are needed to evaluate the value of mesenchymal stem cells and various cytologic chemical signals.