Stem Cells: General Features and Characteristics

What are Stem Cells?

Stem cells are unique because they can transform into many types of cells and reproduce quickly. The body's healing process is dominated by stem cells. New stem cells have shown great promise in many diseases and conditions. We only discovered how to isolate these cells and began using them for transplants. Even though stem cells from a person are 100 percent compatible, it is possible to have stem cells taken from another person. This is especially true if they are not related. Certain markers allow us to determine how compatible donor and recipient cells are. Stem cells found in the umbilical cord's blood have been discovered to be more effective than stem cells obtained from other sources. Current clinical trials are being conducted with stem cells by researchers to add to the growing number of 80 diseases they can treat.

Stem Cells explained

There are many types of cells in your body, more than 200 in fact. Each cell is geared towards a specific function. There are skin cells, blood cells, bone cells, and brain cells. Every organ has specific cells from heart cells to kidney cells.

Stem cells hold the potential to be used in many ways

Your cells did not start with a plan to make your bones, blood, or heart. These undifferentiated cells are found in gestation (when the baby is still in the womb) and are known as embryonic stem cells. These stem cells in the early stages of development are master cells with the potential to transform into any other type of cell in your body.

The first embryonic stem cell was isolated in 1998. There is much controversy about acquiring them. We can also obtain stem cells that have formed a bit later, such as in the umbilical cord. These stem cells are known as adult stem cells and they stay with us throughout our lives. (We will later learn why not all adult stem cells are the same. Although adult stem cells can only become certain types of cells, they share many similarities. For instance, hematopoietic stem cell (Greek for "to make blood", and pronounced heh-maht-po-e-tic), which are found in the umbilical cord's blood can be transformed into any type of blood cells in the body. They also form the basis of our immune system. Mesenchymal stem cells (meh-senki-mal) can also be found in the umbilical cord tissue. They can transform into a host cell, including those in your nervous system and sensory organs.

Stem cells proliferate

We have a few types of stem cells that can be transformed into a variety of different kinds of cells. They are almost like the Renaissance men of cells. But there is another thing that makes stem cell special. It has to do with how they reproduce themselves.

There are two ways for the body to make more cells. The first is often taught in middle school science. Cell division is the process where cells replicate within their membranes before splitting into two identical cells. This is what cells do when they need to regenerate, which we'll touch on in a second.

Another way that the body creates new cells is through stem cells. But stem cells are different. They go through what is known as asymmetric division. This means that they form not one, but two daughters cells. One cell is often an exact copy of itself. A new stem cell is created with a clean slate and another stem cell is ready to transform into a particular type of cell. This is called self-renewal, and stem cells can proliferate or reproduce quickly.

These two methods allow us to produce more cells every day. Your body is actually in constant renewal, as many cells can only live for a certain amount of time. A cell within the stomach lining has a lifespan of about two days. About four months for red blood cells. The brain and nerve cells are expected to live forever. These cells are not able to regenerate quickly and can take many years before they do.

Stem cells can be regenerative.

Different cells have different life spans and are capable of regenerating. However, when there is damage to the cells and the body requires new cells to heal the wound, the stem cells can quickly regenerate more cells. This is where the possibility of introducing new stem cells that can enhance or drive the healing process.

Scientists discovered ways to use stem cells from bone marrow. In 1956, the first stem-cell transplant was done via bone marrow between identical twins. The one twin's leukemia was completely cured.

All stem cell therapies, including this one, involve the introduction of new stem cells to the area in order to promote healing. The stem cell may create a specific type of cell because it is near other cells of the same type. Researchers still have a lot of work to do before they can use stem cells from people not related.

Stem cells must match.

The immune system is able to recognize foreign cells and allows the body's defense mechanisms to work. Although transplants proved successful after 1956 first, only twins were allowed to be transplanted because of their genetic compatibility. In 1958 scientists discovered a protein that is found on almost all cells. This protein allows the body to tell if the cell is in its own or from a foreign one. We finally knew enough about these compatibility marks (called human leukocyte antibodies or HLAs) in 1973 to be able to perform the first non-related bone marrow donation.

Three HLA genes are responsible for the proteins. You inherit one HLA gene from each parent or half of your HLA markers (half from your mother and half from your father) This means siblings have a 25% chance of finding a perfect match, 50% chance of finding a partial match, and a one-in-four chance that they will not match. Seven out of 10 patients who require a transplant aren't able to find a suitable donor. You have two options: rely on your own stem cells or find a public donor.

The HLA-match ensures that the body accepts the transplanted cell. This reduces the chance of developing graft-versus host disease (GvHD), where the transplanted cells attack the recipient. GvHD can occur in 30-40% of recipients if they are not a perfect match, but the donor and recipient are still related. It increases to 60%-80% if the recipient and donor are not related. GvHD symptoms that are milder if the recipient and donor have a good match will likely be milder. GvHD can be fatal.

All adult stem cells may not be equal

In 1978 stem cells in cord blood were discovered. And in 1988, cord blood stem cells were used for the first time in a transplant. Since then, stem cells taken from umbilical cord blood and tissue have been proven to be more beneficial than those from bone marrow. This is due to the fact that stem cells taken from the umbilical cord are more mature and naive than stem cells obtained from other sources. Because cord stem cells have not been exposed to environmental pollutants or disease, they are more open to foreign cells. Inexperience can make them stronger in this instance.

These are just a few of the reasons cord blood stem cells perform better than other stem cell types:

• When needed, preserved cord stem cells can be quickly retrieved.

• A surgical procedure is required to remove bone marrow stem cells.

• Preserved cord stem cell cells are more tolerant to tissue mismatches, and have a lower incidence of graft versus host disease (GVHD).

• The risk of transmissible viral infections is lower in preserved cord stem cells.

• The ability of preserved cord stem cells to cross the blood-brain boundary and differentiate into brain cells is a key feature in some brain disorders.

Stem cells have untapped potential

There are more than 80 diseases that can be treated with hematopoietic-derived stem cells. They are found in the blood of the placenta and umbilical cord after birth. Clinical trials are progressing with mesenchymal stem cell research. These cells can be found within the umbilical cord tissue. They can then become many cells, including those in your nervous system and sensory organs. These trials have shown promise for stem cell therapies for stroke, heart disease, and diabetes, as well as autism, cerebral palsy, and Alzheimer's disease.