Biology Reference
In-Depth Information
(Sigma). Finally, all treated sections were analyzed with the Axioscop2 plus
fluorescence microscope (Zeiss) at low (
100) and high (
400) magnifications.
5.3 Results
5.3.1 Tendon Architecture
The histology of control (CTR) tendons showed, both at 15 and 30 days after
explantation, deeply altered tissues characterized by hypercellularity, irregular
tendon fibers, and composed mostly of collagen type III. In contrast, progressive
tissue remodeling was observed in allotransplanted tendons. In this case, the tissue
showed low cellularity, primarily represented by spindle-shaped cells in active
proliferation (Ki-67 positive). The spindle-shaped cells (tenocyte-like cells),
localized at lesion sites, were trapped between abundant extracellular matrix rich
in collagen type I fibers, primarily oriented parallel to the longitudinal axis of the
tendon.
5.3.2 AFSC Retrieval
At the lesion site, it was possible to retrieve AFSCs (PKH26-positive) at the
periphery of the regenerating tendon even 30 days after transplantation. Most of
the AFSCs appeared as flattened cells, located parallel to the longitudinal axis of the
tendon fibers. Some of them colocalized with the proliferation marker Ki67, similar
to neighboring cells. The transplanted AFSCs participated actively in the process of
tissue repair by contributing directly to the neo-synthesis of collagen type I fibers.
5.3.3 Vascular Organization and Leukocyte Infiltration
In the CTR tendons, numerous small blood vessels (capillaries) were observed; they
were disordered at the lesion site. On the contrary, the blood vessels found in
AFSC-transplanted tendons were located parallel to the longitudinal axis of the
tendon and between the neo-deposited extracellular matrix. A massive presence of
leukocytes (CD45-immunopositive cells) was observed in control tendons, unlike
allografted tendons where the leukocytes were found only inside the blood vessels.
