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Bone marrow-derived matrix metalloproteinase-9 is associated with fibrous adhesion formation after murine flexor tendon injury.

ABSTRACT: The pathogenesis of adhesions following primary tendon repair is poorly understood, but is thought to involve dysregulation of matrix metalloproteinases (Mmps). We have previously demonstrated that Mmp9 gene expression is increased during the inflammatory phase following murine flexor digitorum (FDL) tendon repair in association with increased adhesions. To further investigate the role of Mmp9, the cellular, molecular, and biomechanical features of healing were examined in WT and Mmp9(-/-) mice using the FDL tendon repair model. Adhesions persisted in WT, but were reduced in Mmp9(-/-) mice by 21 days without any decrease in strength. Deletion of Mmp9 resulted in accelerated expression of neo-tendon associated genes, Gdf5 and Smad8, and delayed expression of collagen I and collagen III. Furthermore, WT bone marrow cells (GFP(+)) migrated specifically to the tendon repair site. Transplanting myeloablated Mmp9(-/-) mice with WT marrow cells resulted in greater adhesions than observed in Mmp9(-/-) mice and similar to those seen in WT mice. These studies show that Mmp9 is primarily derived from bone marrow cells that migrate to the repair site, and mediates adhesion formation in injured tendons. Mmp9 is a potential target to limit adhesion formation in tendon healing.

SUBMITTER: Loiselle AE

PROVIDER: S-EPMC3394706 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Bone marrow-derived matrix metalloproteinase-9 is associated with fibrous adhesion formation after murine flexor tendon injury.

Loiselle Alayna E AE Frisch Benjamin J BJ Wolenski Matthew M Jacobson Justin A JA Calvi Laura M LM Schwarz Edward M EM Awad Hani A HA O'Keefe Regis J RJ

PloS one 20120711 7

The pathogenesis of adhesions following primary tendon repair is poorly understood, but is thought to involve dysregulation of matrix metalloproteinases (Mmps). We have previously demonstrated that Mmp9 gene expression is increased during the inflammatory phase following murine flexor digitorum (FDL) tendon repair in association with increased adhesions. To further investigate the role of Mmp9, the cellular, molecular, and biomechanical features of healing were examined in WT and Mmp9(-/-) mice ...[more]

PMID: 22792383

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Project description:Flexor tendon injuries are a common clinical problem, and repairs are frequently complicated by post-operative adhesions forming between the tendon and surrounding soft tissue. Prostaglandin E2 and the EP4 receptor have been implicated in this process following tendon injury; thus, we hypothesized that inhibiting EP4 after tendon injury would attenuate adhesion formation. A model of flexor tendon laceration and repair was utilized in C57BL/6J female mice to evaluate the effects of EP4 inhibition on adhesion formation and matrix deposition during flexor tendon repair. Systemic EP4 antagonist or vehicle control was given by intraperitoneal injection during the late proliferative phase of healing, and outcomes were analyzed for range of motion, biomechanics, histology, and genetic changes. Repairs treated with an EP4 antagonist demonstrated significant decreases in range of motion with increased resistance to gliding within the first three weeks after injury, suggesting greater adhesion formation. Histologic analysis of the repair site revealed a more robust granulation zone in the EP4 antagonist treated repairs, with early polarization for type III collagen by picrosirius red staining, findings consistent with functional outcomes. RT-PCR analysis demonstrated accelerated peaks in F4/80 and type III collagen (Col3a1) expression in the antagonist group, along with decreases in type I collagen (Col1a1). Mmp9 expression was significantly increased after discontinuing the antagonist, consistent with its role in mediating adhesion formation. Mmp2, which contributes to repair site remodeling, increases steadily between 10 and 28 days post-repair in the EP4 antagonist group, consistent with the increased matrix and granulation zones requiring remodeling in these repairs. These findings suggest that systemic EP4 antagonism leads to increased adhesion formation and matrix deposition during flexor tendon healing. Counter to our hypothesis that EP4 antagonism would improve the healing phenotype, these results highlight the complex role of EP4 signaling during tendon repair.

Project description:Background/objectiveStem cell–based therapy has been applied to accelerate the revitalization of allograft tendon into a viable and functional tendon. Although many authors have proposed different methods to help the seeded stem cell distribution in the decellularized allograft, limited success has been achieved as tendon is a high dense connective tissue. We hypothesized that bone marrow stromal cells (BMSCs), seeded through the lateral slit, can regenerate the decellularized tendon (DCT) graft. The cell proliferation, cell viability, and tendon-specific gene expression are increased with the seeded cell density.MethodsEighty-seven flexor digitorum profundus tendons were equally and randomly divided into 6 treatment groups that were seeded with low-density (2 × 107 cells/mL) and high-density (5 × 107 cells/mL) BMSCs through lateral slits cultured for 2 and 4 weeks, DCT without cells, and fresh live tendons. Tendons were evaluated for cell distribution, cell proliferation, cell viability, gene expression of Collagen I and Collagen III, tenogenic markers, and MMPs.ResultsHistologic evaluation revealed BMSCs distributed from the lateral slit to the whole DCT. BMSCs were proliferated and kept viable in lateral slit decellularized tendon (LSDCT) in both seeded cell density groups after 2 and 4 weeks of culture. However, no significant differences in the cell proliferation between both cell density groups at 2 and 4 weeks of culture were observed. The lowest cell viability was found in the high-density group after 4 weeks of culture. BMSCs in LSDCT showed a significant tendency of higher gene expression of Collagen I, Collagen III, tenascin C, MMP2, MMP9, and MMP13 compared to normal tendons in both cell density groups at 2 and 4 weeks of culture.ConclusionBMSCs proliferated and remained viable after 2 and 4 weeks of culture with distribution throughout the lateral slits. Lateral slit preparation allows for the effective delivery and maintenance of mesenchymal cells with proliferation and generating a tenogenic behaviour of DCT in both the low and high cell densities in an in vitro model.The translation potential of this articleRevitalizing the implanted decellularized allograft is important for clinical application. In this study, we demonstrated that the DCT, with lateral slits, could harbour the seeded stem cell and stimulate proliferation with collagen synthesis. This evidence was presented for clinical application of the lateral slit technique, in DCT grafts, which would repopulate the seeded BMSCs during tendon and ligament reconstruction.

Project description:BACKGROUND:Bone marrow aspirate is a primary source for cell-based therapies with increasing value in the world of orthopaedic surgery, especially in revision cases of tendon and ligament repairs. However, cells within peritendinous structures, such as the paratenon and surrounding bursa, contribute to the native tendon-healing response and offer promising cell populations for cell-based repair strategies. Therefore, the purpose of this study is to investigate the efficacy of cells derived from human subacromial bursa as compared with the current gold standard, bone marrow stromal cells (BMSCs), for tendon repairs in an established in vivo immunodeficient murine patellar tendon defect model. HYPOTHESIS:Subacromial bursal cells will show superior survival and engraftment into the host tissue as compared with BMSCs. STUDY DESIGN:Controlled laboratory study. METHODS:Human subacromial bursal and bone marrow aspirate were harvested from the same donor undergoing rotator cuff repair. Cells were transfected with a fluorescent lentiviral vector to permanently label the cells, encapsulated into fibrin gel, and implanted into bilateral full-length central-width patellar tendon defects of immunodeficient mice. Additional surgery was performed on control mice comparing fibrin without cells and natural healing. At the time of sacrifice, all limbs were scanned on a multiphoton microscope to monitor the engraftment of the human donor cells. Afterward, limbs were assigned to either immunohistochemical or biomechanical analysis. RESULTS:As compared with BMSCs, implanted subacromial bursal cells displayed superior tissue engraftment and survival. The main healing response in this defect model was the creation of new healing tissue over the anterior surface of the defect space. The implantation of cells significantly increased the thickness of the anterior healing tissue as compared with control limbs that did not receive cells. Cell proliferation was also increased in limbs that received implanted cells, suggesting that the donor cells stimulated a more robust healing response. Finally, these changes in the healing response did not lead to significant changes in mechanical properties. CONCLUSION:The subacromial bursa, while often removed during rotator cuff repair, may harbor a more suitable cell source for tendon repair than BMSCs, as bursal cells display superior engraftment and survival in tendon tissue. In addition, the subacromial bursa may be a more accessible cell source than bone marrow aspirate. CLINICAL RELEVANCE:The subacromial bursa contains a cell population that responds to tendon injury and may provide a more optimal cell source for tendon repair and regeneration strategies. Therefore, cells could be harvested from this tissue in the future, as opposed to the current practice of bursectomy and debridement.

Dataset Information

Bone marrow-derived matrix metalloproteinase-9 is associated with fibrous adhesion formation after murine flexor tendon injury.

Publications

Bone marrow-derived matrix metalloproteinase-9 is associated with fibrous adhesion formation after murine flexor tendon injury.

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