Combined therapy of platelet-rich plasma and basic fibroblast growth factor using gelatin-hydrogel sheet for rotator cuff healing in rat models

Stable Gastric Pentadecapeptide BPC 157 as Therapy After Surgical Detachment of the Quadriceps Muscle from Its Attachments for Muscle-to-Bone Reattachment in Rats

BACKGROUND

This is a novel rat study using native peptide therapy, focused on reversing quadriceps muscle-to-bone detachment to reattachment and stable gastric pentadecapeptide BPC 157 per-oral therapy for shared muscle healing and function restoration.

METHODS

Pharmacotherapy recovering various muscle, tendon, ligament, and bone lesions, and severed junctions (i.e., myotendinous junction), per-oral in particular (BPC 157/kg/day 10 µg, 10 ng), provides muscle-to-bone reattachment after quadriceps muscle detachment, both complete (rectus muscle) and partial (vastus muscles).

RESULTS

Immediately post-injury, and at 1, 2, 3, 5, 7, 14, 21, 28, 60, and 90 days post-injury, quadriceps muscle-to-bone detachment showed definitive healing failure (impaired walking and permanent knee flexure). Contrarily, macro/microscopic, ultrasonic, magnetic resonance, biomechanical, and functional assessments revealed that BPC 157 therapy recovering effects for all time points were consistent. All parameters of the walking pattern fully improved, and soon after detachment and therapy application, muscle approached the bone, leaving a minimal gap (on ultrasonic assessment), and leg contracture was annihilated. The healing process occurs immediately after detachment from both sides: the muscle and the bone. The reattachment fibers from the ends of the muscle could be traced into the new bone formed at the surface (note, at day 3 post-detachment, increased mesenchymal cells occurred with periosteum reactivation). Consequently, at 3 months, the form was stable, and the balance between the muscle and bone was the following: well-organized bone, newly formed as more cortical bone providing a narrower bone marrow space, and the muscle and mature fibers were oriented parallel to the bone axis and were in close contact with bone.

CONCLUSIONS

Therefore, to achieve quadriceps muscle-to-bone reattachment, the BPC 157 therapy reversing course acts from the beginning, resolving an otherwise insurmountable deleterious course.

Advances in the application of hydrogel-based scaffolds for tendon repair

Tendon injuries often lead to joint dysfunction due to the limited self-regeneration capacity of tendons. Repairing tendons is a major challenge for surgeons and imposes a significant financial burden on society. Therefore, there is an urgent need to develop effective strategies for repairing injured tendons. Tendon tissue engineering using hydrogels has emerged as a promising approach that has attracted considerable interest. Hydrogels possess excellent biocompatibility and biodegradability, enabling them to create an extracellular matrix-like growth environment for cells. They can also serve as a carrier for cells or other substances to accelerate tendon repair. In the past decade, numerous studies have made significant progress in the preparation of hydrogel scaffolds for tendon healing. This review aims to provide an overview of recent research on the materials of hydrogel-based scaffolds used for tendon tissue engineering and discusses the delivery systems based on them.

Fibroblast Growth Factor Soaked Collagen Membrane Shows No Biomechanical or Histological Advantages in the Treatment of Chronic Rotator Cuff Tears in a Rabbit Model

PURPOSE

To investigate the histological and biomechanical effects of a fibroblast growth factor (FGF-2)-soaked collagen membrane used to treat a full-thickness chronic rotator cuff (RC) rupture in a rabbit model.

METHODS

Forty-eight shoulders from 24 rabbits were used. At the beginning of the procedure, 8 rabbits were killed to assess the control group (Group IT) with intact tendons. To establish a chronic RC tear model, a full-thickness subscapularis tear was created on both shoulders of the remaining 16 rabbits and left for 3 months. The transosseous mattress suture technique was used to repair tears in the left shoulder (Group R). The tears in the right shoulder (Group CM) were treated using the same approach, with an FGF-soaked collagen membrane inserted and sutured over the repair site. Three months after the procedure, all rabbits were killed. Biomechanical testing was performed on the tendons to determine failure load, linear stiffness, elongation intervals, and displacement. Histologically, the modified Watkins score was used to evaluate tendon-bone healing.

RESULTS

There was no significant difference among the three groups in terms of failure load, displacement, linear stiffness, and elongation (P > .05). The total modified Watkins score was not affected by applying the FGF-soaked collagen membrane to the repair site (P > .05). Fibrocytes, parallel cells, large-diameter fibers, and the total modified Watkins score were significantly lower in both repair groups when compared to the intact tendon group (P < .05).

CONCLUSIONS

In addition to tendon repair, FGF-2 soaked collagen membrane -application at the repair site provides neither biomechanical nor histological advantages in the treatment of chronic RC tears.

CLINICAL RELEVANCE

FGF-soaked collagen membrane augmentation provides no impact on the chronic RC tear healing tissue. The need to investigate alternative methods that may have a positive effect on healing in chronic RC repairs continues.

Dual Growth Factor Delivery Using Photo-Cross-Linkable Gelatin Hydrogels for Effectively Reinforced Regeneration of the Rotator Cuff Tendon

Rotator cuff tears are currently treated with drugs (steroids and nonsteroidal anti-inflammatory drugs) and surgery. However, the damaged rotator cuff requires a considerable amount of time to regenerate, and the regenerated tissue cannot restore the same level of function as that before the damage. Although growth factors can accelerate regeneration, they are difficult to be used alone because of the risk of degradation and the difficulties in ensuring their sustained release. Thus, hydrogels such as gelatin are used, together with growth factors. Gelatin is a biocompatible and biodegradable hydrogel derived from collagen; therefore, it closely resembles the components of native tissues and can retain water and release drugs continuously, while also showing easily tunable mechanical properties by simple modifications. Moreover, gelatin is a natural biopolymer that possesses the ability to form hydrogels of varying compositions, thereby facilitating effective cross-linking. Therefore, gelatin can be considered to be suitable for rotator-to-tendon healing. In this study, we designed photo-cross-linkable gelatin hydrogels to enhance spacing and adhesive effects for rotator cuff repair. We mixed a ruthenium complex (Ru(II)bpy32+) and sodium persulfate into gelatin-based hydrogels and exposed them to blue light to induce gelation. Basic fibroblast growth factor and bone morphogenetic protein-12 were encapsulated in the gelatin hydrogel for localized and sustained release into the wound, thereby enhancing the cell proliferation. The effects of these dual growth factor-loaded hydrogels on cell cytotoxicity and tendon regeneration in rotator cuff tear models were evaluated using mechanical and histological assessments. The findings confirmed that the gelatin hydrogel was biocompatible and that treatment with the dual growth factor-loaded hydrogels in in vivo rotator cuff tear models promoted regeneration and functional restoration in comparison with the findings in the nontreated group. Therefore, growth factor-loaded gelatin-based hydrogels may be suitable for the treatment of rotator cuff tears.

[Progress and prospect of biological treatment for rotator cuff injury repair]

Objective

To review the research progress in biotherapy of rotator cuff injury in recent years, in order to provide help for clinical decision-making of rotator cuff injury treatment.

Methods

The literature related to biotherapy of rotator cuff injury at home and abroad in recent years was widely reviewed, and the mechanism and efficacy of biotherapy for rotator cuff injury were summarized from the aspects of platelet-rich plasma (PRP), growth factors, stem cells, and exosomes.

Results

In order to relieve patients' pain, improve upper limb function, and improve quality of life, the treatment of rotator cuff injury experienced an important change from conservative treatment to open surgery to arthroscopic rotator cuff repair. Arthroscopic rotator cuff repair plus a variety of biotherapy methods have become the mainstream of clinical treatment. All kinds of biotherapy methods have ideal mid- and long-term effectiveness in the repair of rotator cuff injury. The biotherapy method to promote the healing of rotator cuff injury is controversial and needs to be further studied.

Conclusion

All kinds of biotherapy methods show a good effect on the repair of rotator cuff injury. It will be an important research direction to further develop new biotherapy technology and verify its effectiveness.

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.

Advanced strategies for constructing interfacial tissues of bone and tendon/ligament

Enthesis, the interfacial tissue between a tendon/ligament and bone, exhibits a complex histological transition from soft to hard tissue, which significantly complicates its repair and regeneration after injury. Because traditional surgical treatments for enthesis injury are not satisfactory, tissue engineering has emerged as a strategy for improving treatment success. Rapid advances in enthesis tissue engineering have led to the development of several strategies for promoting enthesis tissue regeneration, including biological scaffolds, cells, growth factors, and biophysical modulation. In this review, we discuss recent advances in enthesis tissue engineering, particularly the use of biological scaffolds, as well as perspectives on the future directions in enthesis tissue engineering.

Platelet-rich plasma does not improve clinical results in patients with rotator cuff disorders but reduces the retear rate. A systematic review and meta-analysis

PURPOSE

To assess whether the use of Platelet-rich plasma (PRP) produces a clinical benefit in patients with rotator cuff disorders, treated either conservatively or surgically.

METHODS

A systematic review was performed according to PRISMA guidelines on three databases (PubMed, Cochrane Library, Web of Science) to identify randomised controlled trials (RCTs) on the use of PRP in patients with rotator cuff disorders, treated either conservatively or surgically. A meta-analysis was performed on articles reporting results for Constant, UCLA, VAS, SST scores and retear rate. The RoB 2.0 and the modified Coleman Methodology Score were used to assess methodological quality.

RESULTS

A total of 36 RCTs (20 surgical, 16 conservative) were included, for a total of 2,443 patients. Conservative treatment showed high heterogeneity and no clear consensus in favour of PRP. The meta-analysis of the studies with surgical treatment showed no benefit in using PRP in any of the clinical outcomes, either at the short or medium/long-term follow-up. However, the retear rate was lower with PRP augmentation (p < 0.001). The overall quality of the studies was moderate to high, with the surgical studies presenting a lower risk of bias than the conservative studies.

CONCLUSION

The use of PRP as augmentation in rotator cuff surgical repair significantly reduces the retear rate. However, no benefits were documented in terms of clinical outcomes. PRP application through injection in patients treated conservatively also failed to present any clear advantage. While there are many studies in the literature with several RCTs of moderate to high quality, the high heterogeneity of products and studies remains a significant limitation to fully understanding PRP potential in this field.

LEVEL OF EVIDENCE

Level I.

Novel therapy using a fish scale collagen scaffold for rotator cuff healing in rat models

BACKGROUND

Large and massive rotator cuff tears are challenging for surgeons because of postoperative complications such as repaired site retears. Recently, collagen extracted from fish scales has gained more attention because fish byproducts are considered a safer collagen source than other animal-derived scaffolds. This study aimed to evaluate the biological efficacy of tilapia scale-derived collagen scaffolds for rotator cuff repair in rat models.

METHODS

The infraspinatus tendon was resected from the greater tuberosity of Sprague-Dawley rats. In the control group, the tendon edge was sutured directly to the humeral head. In the augmentation group, the repaired site was augmented with a tilapia scale-derived collagen scaffold. Histologic examinations were performed at 2 and 4 weeks postoperatively via safranin O and immunofluorescence staining (isolectin B4 and type II collagen) in the bone-tendon junction. For mechanical analysis, the ultimate failure load of the tendon-humeral head complex was evaluated at 6 weeks postoperatively.

RESULTS

During safranin O staining, the repaired enthesis demonstrated greater proteoglycan staining in the augmentation group than in the control group at 4 weeks postoperatively. Compared to controls, the augmentation group had significantly higher vascular staining with isolectin B4 at 2 and 4 weeks postoperatively, type II collagen expression at 4 weeks postoperatively, and ultimate failure load at 6 weeks postoperatively.

CONCLUSION

Augmentation therapy using tilapia scale-derived type I collagen scaffolds promoted angiogenesis and fibrocartilage regeneration at the enthesis and provided higher mechanical strength than controls.

Three Medial All Suture Anchors Improves Contact Force Compared to Two Hard Body Anchors in a Biomechanical Two-Tendon Rotator Cuff Tear Model

Purpose

To biomechanically compare a knotless double-row construct with 3 medial all-suture (3AS) anchors with a standard 2 medial hard body (2HB) anchor construct.

Methods

Twelve matched cadaveric shoulder specimens with a mean age of 57 years (range: 54-61 years) were randomized to receive a knotless double-row repair with either a 3AS or 2HB construct. In the 3AS construct, three 2.6-mm all-suture anchors were placed adjacent to the articular margin and secured laterally with two 4.75-mm knotless hard body anchors. In the 2HB construct, two 4.75-mm medial hard body anchors were placed medially, lateral fixation was identical to the 3AS construct. Creep, displacement, stiffness, and ultimate load were recorded for each sample. In addition, a SynDaver model was used to compare contact pressure between the 2 repair constructs.

Results

There were no differences in cyclic displacement at 1, 30, and 100 cycles (P = .616, .497, .190, respectively), cyclic stiffness (.928), ultimate load (.445), or load to failure (P = .445) between the 2 constructs. The 3AS repair construct had improved contact pressure between tendon and bone when compared with the 2HB construct at loads of 20 N, 30 N, and 40 N (P = .01, .02, and .04, respectively).

Conclusions

Displacement and load to failure properties are similar between knotless constructs using either 2HB or 3AS for the medial row. However, contact force may improve with the use of 3 medial all-suture anchors.

Clinical Relevance

As all-suture anchors are smaller in size when compared with hard body anchors. For this reason, there is potential to place an additional all-suture medial anchor to improve contact force and potentially improve rotator cuff healing when compared with the use of hard body anchors.

The Functions and Mechanisms of Basic Fibroblast Growth Factor in Tendon Repair

Tendon injury is a disorder of the musculoskeletal system caused by overuse or trauma, which is characterized by pain and limitations in joint function. Since tendon healing is slowly and various treatments are generally ineffective, it remains a clinically challenging problem. Recent evidences suggest that basic fibroblast growth factor (bFGF) not only plays an important role in tendon healing, but also shows a positive effect in laboratory experimentations. The purpose of this review is to summarize the effects of bFGF in the tendon healing. Firstly, during the inflammatory phase, bFGF stimulates the proliferation and differentiation of vascular endothelial cells to foster neovascularization. Furthermore, bFGF enhances the production of pro-inflammatory factors during the early phase of tendon healing, thereby accelerating the inflammatory response. Secondly, the cell proliferation phase is accompanied by the synthesis of a large number of extracellular matrix components. bFGF speeds up tendon healing by stimulating fibroblasts to secrete type III collagen. Lastly, the remodeling phase is characterized by the transition from type III collagen to type I collagen, which can be promoted by bFGF. However, excessive injection of bFGF can cause tendon adhesions as well as scar tissue formation. In future studies, we need to explore further applications of bFGF in the tendon healing process.