3.17—Stem cells and medical therapies

A stem cell can divide by mitosis and produce cells that remain stem cells or differentiate. Totipotent cells can form embryonic and extra-embryonic tissues; pluripotent embryonic cells can form embryo cell types; adult stem cells are usually more limited (multipotent).

The morula is an early embryo with highly potent cells; the blastocyst contains an inner cell mass used as an embryonic stem-cell source. Adult tissue stem cells can replace particular cell types, such as blood or intestinal epithelium.

A bone-marrow transplant uses adult stem cells to restore blood-cell production. Embryonic cells could offer a wider range of targets, but their use raises consent, embryo status, regulation and immune-compatibility questions.

“More potent” does not mean automatically safer or better. Medical decisions weigh cell source, differentiation control, rejection risk, evidence and ethical viewpoints rather than potency alone.