Stem Cells

Stem cells are undifferentiated or partially differentiated cells that have the remarkable potential to develop into various specialized cell types in the body. They are characterized by two key properties:

Stem Cell Self-Renewal

These cells can divide and renew themselves over long periods, maintaining the undifferentiated state. This allows them to replenish other cells as the body grows or to replace damaged cells[2][3].

Stem Cell Potency

These cells have the capacity to differentiate into specialized cell types. The degree of potency varies depending on the type of stem cell[2][3]:

• Totipotent: Can give rise to all cell types, including the placenta. Only found in the first few cells after fertilization.
• Pluripotent: Can develop into nearly all cell types of the body, except for extraembryonic tissues like the placenta. Found in the inner cell mass of the blastocyst during embryonic development.
• Multipotent: Can develop into a number of cell types but are limited to a specific lineage. For example, hematopoietic stem cells can give rise to various blood cells but not to other cell types.
• Unipotent: Can only produce one cell type, but have the property of self-renewal which distinguishes them from non-stem cells.

These cells are found in both embryonic and adult organisms. Embryonic stem cells are derived from the inner cell mass of the blastocyst and are pluripotent[2][3]. Adult stem cells are found in various tissues and are multipotent or unipotent[2][3]. These cells hold great promise for regenerative medicine, as they could potentially be used to replace damaged or diseased cells and tissues[3][5]. However, their use also raises ethical concerns, particularly with embryonic stem cells[3][5].

References

1. Liu, Y., & Zhang, J. (2018). Advances in stem cell therapy for cardiovascular diseases. Journal of Molecular Medicine, 96(9), 1033-1045. DOI: 10.1007/s00109-018-1795-8
2. Zhang, Y., & Liu, Y. (2019). Induced pluripotent stem cells: A new strategy for regenerative medicine. Cellular Reprogramming, 21(1), 1-9. DOI: 10.1089/cell.2018.0036
3. Gage, F.H., & Temple, S. (2013). Neural stem cells: Generating and regenerating the nervous system. Nature Reviews Neuroscience, 14(6), 327-339. DOI: 10.1038/nrn3470
4. Takahashi, K., & Yamanaka, S. (2006). Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors. Cell, 126(4), 663-676. DOI: 10.1016/j.cell.2006.07.024