Adult mesenchymal stem cells for the treatment in patients with rotator cuff disease: present and future direction

Bringing tendon biology to heel: Leveraging mechanisms of tendon development, healing, and regeneration to advance therapeutic strategies

Tendons are specialized matrix-rich connective tissues that transmit forces from muscle to bone and are essential for movement. As tissues that frequently transfer large mechanical loads, tendons are commonly injured in patients of all ages. Following injury, mammalian tendons heal poorly through a slow process that forms disorganized fibrotic scar tissue with inferior biomechanical function. Current treatments are limited and patients can be left with a weaker tendon that is likely to rerupture and an increased chance of developing degenerative conditions. More effective, alternative treatments are needed. However, our current understanding of tendon biology remains limited. Here, we emphasize why expanding our knowledge of tendon development, healing, and regeneration is imperative for advancing tendon regenerative medicine. We provide a comprehensive review of the current mechanisms governing tendon development and healing and further highlight recent work in regenerative tendon models including the neonatal mouse and zebrafish. Importantly, we discuss how present and future discoveries can be applied to both augment current treatments and design novel strategies to treat tendon injuries.

A biomechanical comparison of a mesh suture to a polyblend suture in a porcine tendon model

Background

The suture-tendon interface turned out to be the weak point of a repaired rotator cuff. A double rip-stop (DRS) technique was developed to enhance the strength of the suture-tendon interface. The first aim of this study was to compare the suture-tendon interface strength between mesh suture and the No. 2 FiberWire (FW), which is commonly used in the clinic. The second aim was to compare the biomechanical properties of rotator cuff repair between mesh suture and No. 2 FiberWire using a typical suture-bridge (SB) and DRS techniques.

Methods

Eighteen porcine subscapularis tendon (SST) was randomly assigned to the Mesh-tendon group and FiberWire-tendon group. A single suture loop was passed through the SST with a Mesh suture or FiberWire. Thirty-two infraspinatus tendons (ISTs) were randomly assigned to four groups: SB-Mesh group: SB technique with Mesh suture, SB-FW group: SB technique with FiberWire, DRS-Mesh group: DRS technique with Mesh suture, and DRS-FW group: DRS technique with FiberWire. All repaired specimens were underwent failure testing. Failure modes, load to create a 3-mm gap, failure load, and stiffness were compared.

Results

There were no significant differences between the Mesh-tendon group and FiberWire-tendon group regarding the failure load, stiffness, and ultimate stress. When the same technique was used, the rotator cuff repaired with a mesh suture had the similar load to create a 3-mm gap, failure load, and stiffness compared with FiberWire. When the same suture was used, the DRS technique had a significantly higher load to create a 3-mm gap formation and failure load compared with the SB technique.

Conclusions

The repair failure strength and stiffness using the mesh suture were similar to the FiberWire suture regardless of the repair techniques. However, the repair strength in the DRS technique was significantly stronger than the SB technique when the same suture material was used.

Polymorphisms and alterations in gene expression associated with rotator cuff tear and healing following surgical repair: a systematic review

BACKGROUND

Rotator cuff tears (RCTs) are a common cause of shoulder disability, yet both conservative and surgical treatment strategies can lead to poor results in some patient populations. Enhanced understanding of the genetic processes associated with RCTs can assist in the development of more effective management options and help predict individual responses to surgical treatment. This systematic review analyzes the current literature on the genetic footprint associated with RCTs and interprets these findings to enhance the current understanding of RCT pathogenesis, potential treatment regimens, and prognostic biomarkers of outcomes after surgical repair.

METHODS

A systematic search of the Embase, PubMed, and Web of Science electronic databases was performed. Medical Subject Headings (MeSH) and Emtree index terms were formulated from the concept terms "rotator cuff tear," "genetics," and "human," and synonyms of these concepts were applied to the Web of Science search. Articles were screened against predefined inclusion and exclusion criteria. Eligible studies compared gene expression patterns and genetic polymorphisms between cases (with RCTs) and controls (without RCTs). Quality assessment was performed with studies being rated as high, moderate, or poor quality. A modified best-evidence synthesis was applied, and studies were determined to be of strong, moderate, or limited evidence.

RESULTS

The search identified 259 articles. Of these studies, 26 were eligible for review. Two studies were considered poor quality; 15 studies, moderate quality; and 9 studies, high quality. Analysis of these articles found that RCTs were associated with alterations in genes that code for the extracellular matrix, cell apoptosis, immune and inflammatory responses, and growth factor pathways. In particular, there was strong evidence of a significant association between RCTs and the genes MMP3, TNC, and ESRRB. Strong evidence of an association between BMP5 upregulation and successful healing after surgical repair was also found.

CONCLUSION

This review provides strong evidence of an genetic association with RCTs. The genotype and gene expression patterns detailed within this review can assist in deciphering the biological mechanisms resulting in RCTs, as well as predicting an individual's response to surgical repair. Future research could investigate whether manipulating these genes-or their associated signaling pathways-could assist in RCT healing and whether genetic biomarkers could be used clinically to predict patient outcomes after surgical repair of RCTs.