Isolation, characterization, and in vitro differentiation of ovine amniotic stem cells.

Stem cell (SC) regenerative therapy represents an emerging strategy for the treatment of human diseases. Since amniotic fluid-derived cells have been recently proposed as a promising source of human SCs, the present research aimed to amplify in vitro and characterize ovine amniotic fluid-derived SCs collected from the membranes (AMSCs) or fluid (AFSCs). These cells were found to proliferate, express the pluripotent SC markers OCT-4 and TERT, and differentiate in both osteogenic and smooth muscle lineages in vitro. However, AMSCs presented an earlier down-regulation of SC markers and a faster rate of differentiation. Thus, AMSCs and AFSCs may represent sources of characterized pluripotent SCs that can be easily collected and amplified in vitro. These ovine SCs may be used in preclinical studies on large animals to develop future human therapies.

An ovine preimmune foetal model to study the effect of cellular therapies for myocardic diseases.

The ovine foetus is an ideal model for preclinical medical studies of cell therapies. It allows us to follow the behaviour of repairing cells inserted into a favourable physiological microenvironment in an animal species more closely related to humans than the rat or rabbit. In addition, the preimmune foetus is able to support cell engraftment by eliminating the problems of tissue rejection. Labelled fibroblasts were transplanted into the myocardium of preimmune foetuses, injecting through a disposable bowed mouth pipette into the left ventricular apex. Two weeks later, foetuses were isolated by laparotomy and each heart was collected and morphologically analyzed. No cases of abortion or postoperative complications in mothers or foetuses occurred. Macroscopically, the isolated hearts did not display any abnormality apart from a small petechia at the injection site. Tissue sections did not show any sign of acute tissue inflammation and viable labelled cells were easily identified among myocardiocytes. This model system guarantees a reduced damage in the engrafted tissue, a high survival and easy retrieval of the injected cells. The direct injection of cells into the preimmune ovine foetus myocardium can be satisfactorily performed to control tissue delivery and to reduce the risk of cell loss and dispersion.