Biology Reference
In-Depth Information
5.1
Introduction
Tendinopathy is a very common condition; it is debilitating, painful, and usually
caused by overwork. This medical condition affects patient quality of life and
causes a sharp decline in locomotor skills. For this reason, tendinopathies are
most common and feared in the world of sports, both in the medical field and in
veterinary medicine (Dowling et al.
2000
;J
arvinen et al.
2001
), where they are
considered among the leading causes of reduced income in the horse racing
industry. The concern associated with this medical condition is also increased by
the impossibility of successfully treating this pathology using conventional treatments
(physical and pharmacological therapies). For this reason, tendinopathies are among
the diseases for which the use of regenerative cell therapy is viewed with increasing
interest (Andres and Murrell
2008
).
Stem cells are the basis of regenerative medicine, an innovative therapeutic
approach that aims to repair tissues or organs damaged by congenital or acquired
pathologies through the introduction of pluri/multi/unipotent cells (Bajada et al.
2008
). Embryonic stem cells, for their biological characteristics (pluripotent cells),
are the most promising cell source for therapeutic approaches. In fact, they prolif-
erate rapidly and can differentiate into progenitor cells of different tissue types.
However, strong ethical and legal constraints related to their use as well as their
proven tumorigenic results considerably restrict their study and use in preclinical
and clinical fields (Toda et al.
2007
). In addition, the greater genomic stability and
the absence of ethical limits of adult stem cells have discouraged further embryonic
stem cell use (Smith et al.
2007
). In fact, given the small numbers of adult stem
cells, the difficulties encountered in their isolation and their low propensity to
proliferate in culture do not fulfill the biological requirements necessary for
subsequent stem cell transplantation in damaged tissues, in which these cells should
restore full function. For this reason, there is increasing attention with regard to new
sources of stem cells. Considerable interest exists in fetal stem cells, which combine
ease of availability, lack of ethical limitations, and favorable biological
characteristics, such as a high proliferative potential, high differentiation plasticity
(multi-pluripotent), reduced tumorigenic drift, and high tolerance in recipient
tissues (anti-inflammatory and immunomodulatory properties; De Coppi et al.
2007
).
In this study, the regenerative properties of fetal amniotic fluid-derived stem
cells (AFSCs) were evaluated in an experimentally injured tendon. This preclinical
study was performed in sheep, which was chosen for easy availability of AFSCs (at
slaughter) and similarities to the human morpho-functional skeletal muscle appara-
tus. The regenerative properties of the transplanted AFSC in the injured calcaneal
tendon were evaluated by, combining histological and immunohistochemical (IHC)
techniques, studying the architecture of the repaired tendon and verifying the
incidence of inflammatory processes 15 and 30 days after stem cell allotrans-
plantation. AFSC survival and integration into the injured tendon were monitored
by vital lipophilic dye (PKH26) which allowed the identification of the transplanted
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