Might the Masson trichrome stain be considered a useful method for categorizing experimental tendon lesions?

Strain injuries of tendons are the most common orthopedic injuries in athletic subjects, be they equine or human. When the tendon is suddenly damaged, an acute inflammatory phase occurs whereas its repetitive overloading may cause chronic injuries. Currently the criteria used for grading injuries are general and subjective, and therefore a reliable grading method would be an improvement. The main purpose of this study was to assess qualitatively the histological pattern of Masson trichrome stain in healthy and injured tendons; indeed, the known "paradox" of Masson staining was used to create an evaluation for the matrix of tendons, following experimental lesions and natural repair processes. A statistically significant difference of aniline-staining between healthy and lesioned tendons was observed. Overall, we think that the Masson staining might be regarded as an informative tool in discerning the collagen spatial arrangement and therefore the histological characteristics of tendons.

Successful recellularization of human tendon scaffolds using adipose-derived mesenchymal stem cells and collagen gel.

The major goal of regenerative medicine is to determine experimental techniques that take maximal advantage of reparative processes that occur naturally in the animal body. Injection of mesenchymal stem cells into the core of a damaged tendon represents such an approach. Decellularization of native tendons as potential targets and seeding protocols are currently under investigation. The aim of our study was to manufacture a recellularized biocompatible scaffold from cadaveric tissue for use in total or partial tendon injuries. Results showed that it was possible to introduce proliferating cells into the core of a decellularized tendon to treat the scaffold with a collagen gel. The method was effective in maintaining scaffold extracellular matrix and for expressing collagen type I and cartilage oligomeric matrix protein by injecting mesenchymal stem cells.

Effects of in vivo applications of peripheral blood-derived mesenchymal stromal cells (PB-MSCs) and platlet-rich plasma (PRP) on experimentally injured deep digital flexor tendons of sheep.

Tendon injuries, degenerative tendinopathies, and overuse tendinitis are common in races horses. Novel therapies aim to restore tendon functionality by means of cell-based therapy, growth factor delivery, and tissue engineering approaches. This study examined the use of autologous mesenchymal stromal cells derived from peripheral blood (PB-MSCs), platelet-rich plasma (PRP) and a combination of both for ameliorating experimental lesions on deep digital flexor tendons (DDFT) of Bergamasca sheep. In particular, testing the combination of blood-derived MSCs and PRP in an experimental animal model represents one of the few studies exploring a putative synergistic action of these treatments. Effectiveness of treatments was evaluated at 30 and 120 days comparing clinical, ultrasonographic, and histological features together with immunohistochemical expression of collagen types 1 and 3, and cartilage oligomeric matrix protein (COMP). Significant differences were found between treated groups and their corresponding controls (placebo) regarding tendon morphology and extracellular matrix (ECM) composition. However, our results indicate that the combined use of PRP and MSCs did not produce an additive or synergistic regenerative response and highlighted the predominant effect of MSCs on tendon healing, enhanced tissue remodeling and improved structural organization.