Biology and augmentation of tendon-bone insertion repair

Surgical reattachment of tendon and bone such as in rotator cuff repair, patellar-patella tendon repair and anterior cruciate ligament (ACL) reconstruction often fails due to the failure of regeneration of the specialized tissue ("enthesis") which connects tendon to bone. Tendon-to-bone healing taking place between inhomogenous tissues is a slow process compared to healing within homogenous tissue, such as tendon to tendon or bone to bone healing. Therefore special attention must be paid to augment tendon to bone insertion (TBI) healing. Apart from surgical fixation, biological and biophysical interventions have been studied aiming at regeneration of TBI healing complex, especially the regeneration of interpositioned fibrocartilage and new bone at the healing junction. This paper described the biology and the factors influencing TBI healing using patella-patellar tendon (PPT) healing and tendon graft to bone tunnel healing in ACL reconstruction as examples. Recent development in the improvement of TBI healing and directions for future studies were also reviewed and discussed

Expression of Bone Morphogenetic Protein-2 in the Chondrogenic and Ossifying Sites of Calcific Tendinopathy and Traumatic Tendon Injury Rat Models

<p>Abstract</p> <p>Background</p> <p>Ectopic chondrogenesis and ossification were observed in a degenerative collagenase-induced calcific tendinopathy model and to a lesser extent, in a patellar tendon traumatic injury model. We hypothesized that expression of bone morphogenetic protein-2 (BMP-2) contributed to ectopic chondrogenesis and ossification. This study aimed to study the spatial and temporal expression of BMP-2 in our animal models.</p> <p>Methods</p> <p>Seventy-two rats were used, with 36 rats each subjected to central one-third patellar tendon window injury (C1/3 group) and collagenase-induced tendon injury (CI group), respectively. The contralateral limb served as controls. At week 2, 4 and 12, 12 rats in each group were sacrificed for immunohistochemistry and RT-PCR of BMP-2.</p> <p>Results</p> <p>For CI group, weak signal was observed at the tendon matrix at week 2. At week 4, matrix around chondrocyte-like cells was also stained in some samples. In one sample, calcification was observed and the BMP-2 signal was observed both in the calcific matrix and the embedded chondrocyte-like cells. At week 12, the staining was observed mainly in the calcific matrix. Similar result was observed in C1/3 group though the immunopositive staining of BMP-2 was generally weaker. There was significant increase in BMP-2 mRNA compared to that in the contralateral side at week 2 and the level became insignificantly different at week 12 in CI group. No significant increase in BMP-2 mRNA was observed in C1/3 group at all time points.</p> <p>Conclusion</p> <p>Ectopic expression of BMP-2 might induce tissue transformation into ectopic bone/cartilage and promoted structural degeneration in calcific tendinopathy.</p

Elastin is Localised to the Interfascicular Matrix of Energy Storing Tendons and Becomes Increasingly Disorganised With Ageing

Tendon is composed of fascicles bound together by the interfascicular matrix (IFM). Energy storing tendons are more elastic and extensible than positional tendons; behaviour provided by specialisation of the IFM to enable repeated interfascicular sliding and recoil. With ageing, the IFM becomes stiffer and less fatigue resistant, potentially explaining why older tendons become more injury-prone. Recent data indicates enrichment of elastin within the IFM, but this has yet to be quantified. We hypothesised that elastin is more prevalent in energy storing than positional tendons, and is mainly localised to the IFM. Further, we hypothesised that elastin becomes disorganised and fragmented, and decreases in amount with ageing, especially in energy storing tendons. Biochemical analyses and immunohistochemical techniques were used to determine elastin content and organisation, in young and old equine energy storing and positional tendons. Supporting the hypothesis, elastin localises to the IFM of energy storing tendons, reducing in quantity and becoming more disorganised with ageing. These changes may contribute to the increased injury risk in aged energy storing tendons. Full understanding of the processes leading to loss of elastin and its disorganisation with ageing may aid in the development of treatments to prevent age related tendinopathy

Uncovering the effect of low-frequency static magnetic field on tendon-derived cells: from mechanosensing to tenogenesis

Magnetotherapy has been receiving increased attention as an attractive strategy for modulating cell physiology directly at the site of injury, thereby providing the medical community with a safe and non- invasive therapy. Yet, how magnetic eld in uences tendon cells both at the cellular and molecular levels remains unclear. Thus, the in uence of a low-frequency static magnetic eld (2 Hz, 350 mT) on human tendon-derived cells was studied using di erent exposure times (4 and 8 h; short-term studies) and di erent regimens of exposure to an 8h-period of magnetic stimulation (continuous, every 24 h or every 48 h; long-term studies). Herein, 8 h stimulation in short-term studies signi cantly upregulated the expression of tendon-associated genes SCX, COL1A1, TNC and DCN (p < 0.05) and altered intracellular Ca2+ levels (p < 0.05). Additionally, every 24 h regimen of stimulation signi cantly upregulated COL1A1, COL3A1 and TNC at day 14 in comparison to control (p < 0.05), whereas continuous exposure di erentially regulated the release of the immunomodulatory cytokines IL-1β and IL-10 (p < 0.001) but only at day 7 in comparison to controls. Altogether, these results provide new insights on how low-frequency static magnetic eld ne-tune the behaviour of tendon cells according to the magnetic settings used, which we foresee to represent an interesting candidate to guide tendon regeneration.info:eu-repo/semantics/publishedVersio

Anatomical heterogeneity of tendon: Fascicular and interfascicular tendon compartments have distinct proteomic composition

This study was funded by the BBSRC (BB/K008412/1)

Biology of tendon stem cells and tendon in aging

202006 bcrcVersion of RecordPublishe

Let the dying shine: are they lessons of dying or lessons of living? Meaning making of patients with terminal cancer in Chinese cultural context

Free Paper Session - Psychosocial Oncology: A65The 16th Hong Kong International Cancer Congress (HKICC 2009), Hong Kong, 4-6 November 2009