Stem cells are the foundation for every organ and tissue in your body. There are many different types of stem cells that come from different places in the body or are formed at different times in our lives.
These include embryonic stem cells that exist only at the earliest stages of development and various types of tissue-specific or adult stem cells that appear during fetal development and remain in our bodies throughout life.
All stem cells can self-renew make copies of themselves and differentiate develop into more specialized cells. Beyond these two critical abilities, though, stem cells vary widely in what they can and cannot do and in the circumstances under which they can and cannot do certain things.
This is one of the reasons researchers use all types of stem cells in their investigations. Embryonic stem cells are obtained from the inner cell mass of the blastocyst , a mainly hollow ball of cells that, in the human, forms three to five days after an egg cell is fertilized by a sperm.
In normal development, the cells inside the inner cell mass will give rise to the more specialized cells that give rise to the entire body—all of our tissues and organs. Stem cells are the foundation of development in plants, animals and humans. In humans, there are many different types of stem cells that come from different places in the body or are formed at different times in our lives. These include embryonic stem cells that exist only at the earliest stages of development and various types of tissue-specific or adult stem cells that appear during fetal development and remain in our bodies throughout life.
Stem cells are defined by two characteristics:. Beyond these two things, though, stem cells differ a great deal in their behaviors and capabilities. Other cells are multipotent, meaning they can generate a few different cell types, generally in a specific tissue or organ.
As the body develops and ages, the number and type of stem cells changes. Stem cells can cure diseases! Stem cells can extend our lifespan! But in actual what these magic stem cells are, how they differ from normal body cells. Our body is made up of about 30 trillion cells.
Imagine our body as factory and cells are manpower in the factory. Normal cells present in the body are the differentiated cells that perform a special function in a localised area in the body. For example blood cells present in blood transport oxygen and nutrients to the rest of the body.
Neurons are cells present in the nervous system and transmit signals to body from the brain. Then in factory, maintenance team is also present in form of stem cells. Scientists have used MSCs to create new body tissues, such as bone, cartilage, and fat cells. They may one day play a role in solving a wide range of health problems.
Scientists create these in a lab, using skin cells and other tissue-specific cells. These cells behave in a similar way to embryonic stem cells, so they could be useful for developing a range of therapies.
To grow stem cells, scientists first extract samples from adult tissue or an embryo. They then place these cells in a controlled culture where they will divide and reproduce but not specialize further. Stem cells that are dividing and reproducing in a controlled culture are called a stem-cell line. Researchers manage and share stem-cell lines for different purposes.
They can stimulate the stem cells to specialize in a particular way. This process is known as directed differentiation. Until now, it has been easier to grow large numbers of embryonic stem cells than adult stem cells.
However, scientists are making progress with both cell types. Researchers categorize stem cells, according to their potential to differentiate into other types of cells. Embryonic stem cells are the most potent, as their job is to become every type of cell in the body. Totipotent : These stem cells can differentiate into all possible cell types. The first few cells that appear as the zygote starts to divide are totipotent. Pluripotent : These cells can turn into almost any cell.
Cells from the early embryo are pluripotent. Multipotent : These cells can differentiate into a closely related family of cells. Adult hematopoietic stem cells, for example, can become red and white blood cells or platelets. Oligopotent : These can differentiate into a few different cell types. Adult lymphoid or myeloid stem cells can do this. Unipotent : These can only produce cells of one kind, which is their own type. However, they are still stem cells because they can renew themselves.
Examples include adult muscle stem cells. Embryonic stem cells are considered pluripotent instead of totipotent because they cannot become part of the extra-embryonic membranes or the placenta. First, with the right stimulation, many stem cells can take on the role of any type of cell, and they can regenerate damaged tissue, under the right conditions. This potential could save lives or repair wounds and tissue damage in people after an illness or injury.
Scientists see many possible uses for stem cells. Until now, a person who needed a new kidney, for example, had to wait for a donor and then undergo a transplant. There is a shortage of donor organs but, by instructing stem cells to differentiate in a certain way, scientists could use them to grow a specific tissue type or organ.
They can then repair a severe burn or another injury by grafting this tissue onto the damaged skin, and new skin will grow back. In , a team of researchers from Massachusetts General Hospital reported in PNAS Early Edition that they had created blood vessels in laboratory mice, using human stem cells. Within 2 weeks of implanting the stem cells, networks of blood-perfused vessels had formed.
The quality of these new blood vessels was as good as the nearby natural ones.
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