Increased content of type III collagen at the rupture site of human Achilles tendon.
ABSTRACT We compared the type I and III collagen amounts and cross-linked telopeptides at the rupture site and two other sites of the same tendon. Tendon samples of ten individuals with total Achilles tendon rupture and six healthy cadavers were collected. The newly synthesized type I and III procollagens were assessed by extracting the soluble propeptides PINP, PICP and PIIINP. The insoluble matrix was solubilized by heat denaturation and trypsin digestion. Hydroxyproline, the cross-linked telopeptide structures of type I (ICTP and SP 4) and III collagens (IIINTP) and the degradation product of type III collagen (tryptic PIIINP) were measured from the digests. The type III collagen content was significantly increased at the rupture site when compared to control sites (5- and 12-fold increased) or cadavers (5-fold increased). No changes in the amounts of newly synthesized type I and III procollagens were observed. The ICTP content decreased and the SP 4/ICTP ratio increased along with ageing, suggesting a structural change in the type of cross-link in the carboxyterminal telopeptide of type I collagen. Type III collagen has accumulated at the rupture site probably due to microtraumas and the subsequent healing process. The increased content of type III collagen can cause thinner collagen fibers, decrease the tensile strength and may finally result in total rupture of the tendon. The age-related change in the nature of the cross-link in the carboxyterminal telopeptide may contribute to this weakening.
Article: Extracorporeal Shock Wave Treatment (ESWT) Improves In Vitro Functional Activities of Ruptured Human Tendon-Derived Tenocytes.[show abstract] [hide abstract]
ABSTRACT: In vitro models of human tenocytes derived from healthy as well as from ruptured tendons were established, characterized and used at very early passage (P1) to evaluate the effects of Extracorporeal Shock Wave Treatment (ESWT). The molecular analysis of traditional tenocytic markers, including Scleraxis (Scx), Tenomodulin (Tnm), Tenascin-C (Tn-C) and Type I and III Collagens (Col I and Col III), permitted us to detect in our samples the simultaneous expression of all these genes and allowed us to compare their levels of expression in relationship to the source of the cells and treatments. In untreated conditions, higher molecular levels of Scx and Col I in tenocytes from pathological compared to healthy samples have been detected, suggesting - in the cells from injured tendon - the natural trigger of an early differentiation and repairing program, which depends by Scx and requires an increase in collagen expression. When ESWT (at the dose of 0.14 mJ/mm(2)) was applied to cultured tenocytes explanted from injured source, Scx and Col I were significantly diminished compared to healthy counterpart, indicating that such natural trigger maybe delayed by the treatment, in order to promote cellular repair. Herein, we show for the first time that ESWT enhances in vitro functional activities of ruptured tendon-derived tenocytes, such as proliferation and migration, which could probably contributes to tendon healing in vivo.PLoS ONE 01/2012; 7(11):e49759. · 4.09 Impact Factor
[show abstract] [hide abstract]
ABSTRACT: Tendon injuries are a common cause of morbidity and a significant health burden on society. Tendons are structural tissues connecting muscle to bone and are prone to tearing and tendinopathy, an overuse or degenerative condition that is characterized by failed healing and cellular depletion. Current treatments, for tendon tear are conservative, surgical repair or surgical scaffold reconstruction. Tendinopathy is treated by exercises, injection therapies, shock wave treatments or surgical tendon debridement. However, tendons usually heal with fibrosis and scar tissue, which has suboptimal tensile strength and is prone to reinjury, resulting in lifestyle changes with activity restriction. Preclinical studies show that cell therapies have the potential to regenerate rather than repair tendon tissue, a process termed tenogenesis. A number of different cell lines, with varying degrees of differentiation, have being evaluated including stem cells, tendon derived cells and dermal fibroblasts. Even though cellular therapies offer some potential in treating tendon disorders, there have been few published clinical trials to determine the ideal cell source, the number of cells to administer, or the optimal bioscaffold for clinical use.Stem cells international. 01/2012; 2012:637836.
Article: Towards improved collagen assessment: polarization-sensitive optical coherence tomography with tailored reference arm polarization.[show abstract] [hide abstract]
ABSTRACT: Single channel PS-OCT has advantages for assessing birefringent tissue components in various clinical scenarios, with implications for assessing pathology, ranging from osteoarthritis to myocardial infarction. While the technique has been successfully used both in vitro and in vivo, there have been limited attempts to optimize single channel PS-OCT with respect to performance, particularly paddle rotation. In this study, we developed and tested a new approach for the real-time assessment of birefringence through tailoring of reference arm polarization. Different polarization rotation patterns, as depicted on a Poincare sphere, were assessed with polarization filters and retarders. When further tested in tissue, PS-OCT assessments of bovine cartilage and tendon demonstrated that contrast was sensitive to the pattern selected, indicating that rotation pattern influenced birefringence assessment and providing insights into optimal patterns. We also discuss the difference between diagnostic accuracy and precision with respect to both the construction and application of PS-OCT embodiments.International Journal of Biomedical Imaging 01/2012; 2012:892680.