Stem cells fulfill various functions, being a field of recent research. Progress is being made every day in their analysis, with new discoveries about their application.
Index
Stem cells – What are they
Adult or somatic stem cells exist throughout the body after embryonic development and are found within different types of tissue. These stem cells have been found in tissues such as the brain, bone marrow, blood, blood vessels, skeletal muscles, skin, and liver. They remain in a resting or undivided state for years until activated by disease or tissue injury. Stem cells are harvested from adult tissue or from a dividing zygote in a culture dish.
Stem cells – Origin
Commonly, they derive from two main sources:
- Those produced during the blastocyst phase of embryological development (embryonic stem cells) and
Adult tissue (adult stem cells). - Both types are generally characterized by their potency or potential to differentiate into different types of cells (such as skin, muscle, bone, etc.).
Stem cells – Characteristics
Adult stem cells can divide or self-renew indefinitely, allowing them to generate a range of cell types from the original organ or even regenerate the entire original organ.
Embryonic stem cell
Embryonic stem cells are derived from a four- or five-day-old human embryo that is in the blastocyst phase of development. Embryos are generally extras that have been created in in vitro fertilization (IVF) clinics where multiple eggs are fertilized in a test tube, but only one is implanted into a woman.
Sexual reproduction begins when a man’s sperm fertilizes a female’s egg (ovum) to form a single cell called a zygote. The single zygote cell begins a series of divisions, forming 2, 4, 8, 16 cells, etc. After four to six days, before implantation in the uterus, in the blastocyst.
The blastocyst consists of the embryoblasts (internal) and the trophoblast (external). The external one becomes part of the placenta, and the internal cell is the group that become all the structures of an adult organism. This last mass is the source of embryonic stem cells: totipotent cells (cells with the full potential to become any cell in the body). In a normal pregnancy, the blastocyst occurs until the end of the 10th week of gestation.
Stem cells – Classification
Embryonic stem cells are the most powerful, turning into all types of cells in the body. The full classification includes:
- Totipotente
- Pluripotent
- Multipotente
Stem cells – Identification
Most tests are based on making sure that stem cells do not differentiate and are capable of self-renewal. Tests are often carried out in the laboratory to verify these properties.
One way to identify stem cells in a laboratory, and the standard procedure for analyzing bone marrow or hematopoietic stem cells (HSCs), is by transplanting a cell to save an individual without HSC. If the stem cell produces new blood and immune cells, it shows its potency.
Clonogenic assays (a laboratory procedure) can also be used in vitro to assess whether individual cells can differentiate and self-renew. Researchers can also inspect cells under a microscope to see if they are healthy and undifferentiated or if they can examine chromosomes.
To test whether human embryonic stem cells are pluripotent, scientists allow cells to differentiate spontaneously in cell culture, manipulate cells to differentiate to form specific cell types, or inject the cells into an immunosuppressed mouse to assess the formation of an teratoma (a benign tumor that contains a mixture of differentiated cells).
Stem cells – Benefits
While stem cells serve no function, many have the ability to perform any function once they are trained to specialize.
Every cell in the body, for example, is derived from the first few stem cells formed in the early stages of embryological development. Therefore, stem cells extracted from embryos can be induced to become any desired cell type. This property makes stem cells powerful enough to regenerate damaged tissue under the right conditions.
Regeneration of organs and tissues
Currently, organs must be donated and transplanted, but the demand for organs far exceeds the supply. Stem cells could potentially be used to grow a particular type of tissue or organ if they are directed to differentiate in a certain way. Stem cells found just under the skin, for example, have been used to engineer new skin tissues that can be grafted onto burn victims.
Treatment of cardiovascular diseases
The scientists extracted precursor vascular cells derived from human-induced pluripotent stem cells from a group of adults with type 1 diabetes, as well as from another group of “healthy” adults. They were then implanted on the surface of the brains of the mice.
The authors explained that the use of stem cells to repair or regenerate blood vessels could eventually help treat human patients with cardiovascular and vascular diseases.
Treatment of brain diseases
Parkinson’s and Alzheimer’s can be treated by replenishing damaged tissue, restoring specialized brain cells that prevent unnecessary muscles from moving. Embryonic stem cells have recently been directed to differentiate into these types of cells, so the treatments are promising.
Dr. Samantha Robson ( CRN: 0510146-5) is a nutritionist and website content reviewer related to her area of expertise. With a postgraduate degree in Nutrition from The University of Arizona, she is a specialist in Sports Nutrition from Oxford University and is also a member of the International Society of Sports Nutrition.
