Achilles Tendon Regeneration can be Improved by Amniotic Epithelial Cell Allotransplantation

Abstract

Amniotic epithelial cells (AECs) are ideal seed cells for tissue regeneration, but no research has yet been reported on their tendon regeneration potential. This study investigated the efficiency of AEC allotransplantation for tendon healing, as well as the mechanism involved. To this aim ovine AECs, characterized by specific surface and stemness markers (CD14-, CD49f, CD29, CD166, OCT4, SOX2, NANOG, TERT), were allotransplanted into experimentally induced tissue defects in sheep Achilles tendon. In situ tissue repair revealed that AEC-treated tendons had much better structural and mechanical recoveries than control ones during the early phase of healing. Immunohistochemical and biochemical analyses indicated that extracellular matrix remodeling was more rapid and that immature collagen fibers were completely replaced by mature ones in 28 days. Moreover, spatial-temporal analysis of cellularity, proliferation index, vascular area, and leukocyte infiltration revealed that AECs induced a specific centripetal healing process that first started in the tissue closer to the healthy portion of the tendons, where AECs rapidly migrated to then progress through the core of the lesion. This peculiar healing evolution could have been induced by the growth factor stimulatory influence (TGF-b1 and VEGF) and/or by the host progenitor cells recruitment, but also as the consequence of a direct tenogenic AEC differentiation resulting in the regeneration of new tendon matrix. These findings demonstrate that AECs can support tendon regeneration, and their effects may be used to develop future strategies to treat tendon disease characterized by a poor clinical outcome in veterinary medicine.

Amniotic membrane as an option for treatment of acute Achilles tendon injury in rats

“…Similar to our result, Barboni et al 12 observed, in Achilles tendon, that immature collagen fibers were completely replaced by mature ones in 28 days. And, stated that the increase in maturity of tendon was due to the stimulus induced by cells derivate from amniotic membrane, which provide a positive paracrine environment, thus accelerating the recovery of normal tendon microstructure and biomechanical properties.…”

“…Organization of the collagen fibers was used to generate a score in order to evaluate the alignment of these fibers in the different groups and experimental times based on the score system used by Barboni et al 12 . The analysis was made on the injured tendon area with an increase of x20, totaling 5 samples per group of all experimental times studied.…”

“…In addition to these biological properties, others such as biocompatibility, permeability, highly flexibility, transparency, and stability make the MA a tissue with reasonable mechanical properties and, thus a potential scaffold the growth, cell adhesion and migration, characteristics required for tissue engineering 6 . Pre-clinical studies have successfully used the amniotic epithelial cells (AECs) [12][13] to accelerate the repair process in tendinopathies. However, cell culture can result in a loss of some of its own cellular factors, such as cytokines as well as growth and differentiation factors, which are present in the AM microenvironment.…”

Conditioned Medium from Horse Amniotic Membrane-Derived Multipotent Progenitor Cells: Immunomodulatory Activity In Vitro and First Clinical Application in Tendon and Ligament Injuries In Vivo

“…The opportune time of implantation, together with the higher plasticity and proliferative capacity of AMCs compared to BM-MSCs [8], represents the main features of interest for this novel heterologous approach for the treatment of equine tendon diseases. In addition, recent studies of in vivo transplantation of ovine amniotic membrane-derived epithelial cells into the ovine Achilles tendon [12] or into spontaneous equine tendon injuries [13], demonstrated production of ovine collagen, thereby supporting the possibility of applying amniotic epithelial cells for tenocyte regeneration. In regard to the use of MSCs, it is still unclear as to whether the major contribution of MSCs to the tendon-healing process is through their ability to differentiate into tenocytes, whether they instead act mainly to supply immunomodulatory and trophic factors [14,15], or whether a combination of these two mechanisms occurs [16,17].…”

Pilot experimental study on amniotic epithelial mesenchymal cell transplantation in natural occurring tendinopathy in horses.

“…Moreover, these cells can be stored thanks to cryopreservation and used for allogeneic transplantation in veterinary medicine. Previous experimental studies, in mechanically-induced acute tendon injuries in large animals species (sheep), have shown their good tolerance by the host, due to their low immunologic potential, and their efficacy in regenerating tendon 6,17 . Very good clinical results have been also obtained after transplantation into equine SDF acute tendinopathies, with restoration of a quite normal US pattern of tendon fibers orientation 17 Amniotic epithelial cell and tendinopathy: ultrasound and histological results In the regenerating area a higher nuclei concentration and a lower density of the extracellular matrix fibers in comparison with the healthy tendon are evident.…”