Placenta as a source of stem cells and as a key organ for fetomaternal tolerance

The placenta encloses the very beginnings of the mystery of life, but discloses an ever-increasing amount of information toward our understanding not only of cell development, maturation, and differentiation, but to an even greater extent, the fundamental mechanisms of immunological tolerance. For many years, the human placenta has attracted the attention of scientists because of the essential role it plays in development of the growing embryo by facilitating gas and nutrient exchange between the mother and fetus, while this tissue has intrigued researchers for an even longer time because of its role in maintaining fetomaternal tolerance. More recently, this tissue has also been investigated as a potential source of stem cells for application in regenerative medicine.