Stem Cells: A Historical Review about Biological, Religious, and Ethical Issues

Table 1

The different sources of stem cells with different plasticity and differentiation.

Stem cell plasticity
Totipotent/omnipotent	Pluripotent	Multipotent	Oligopotent	Unipotent
They are cells with the most undifferentiated cell form during embryonic development (e.g., the fertilized oocyte (zygote)) up to the stage of the first blastomeres (i.e., three to four days after fertilization). Are single cells that can give rise to a new organism with adequate maternal support. So, it can give rise to all extra-embryonic tissues, tissues of the body, and of the germ line.	They can differentiate into cell types from the ectoderm, endoderm, and mesoderm, which then produce all cell types for all tissues and organs. The best-known pluripotent stem cells are embryonic (isolated from the internal cell mass (ICM) of the blastocyst).	They can differentiate into discrete cell types (e.g., several types of blood cell-like lymphocytes, monocytes, neutrophils, bone cells or other nonblood cell type, and others. The best now is the mesenchymal cells (MSCs) in the bone marrow, adipose tissue, Wharton’s jelly in umbilical cord blood, dental tissues, and peripheral blood.	These stem cells can self-renew and differentiate into two or more cells that belong to a specific type of tissue (e.g., hematopoietic stem cells, the bronchioalveolar stem cells, or BASCs).	They can self-renew and differentiate into a single specific cell type forming a single cell line (e.g., the muscle stem cells).

Inside the Wharton’s jelly (substantia gelatinea funiculi umbilicalis) in umbilical cord, there is a cell population that has stem characteristics and is made up of the mesenchymal cells of the layer (MSCs). They exhibit cell adhesion characteristics while phenotypically expressing a specific set of surface antigens (including CD73, CD90, and CD105 stem cells).