Where can you find stem cells?

Where can you find stem cells?

Stem cells are found in multicellular organisms like animals and plants. They are biological cells.  They are very important for any living thing. Stem cells are different from other types of cells.They have a unique capability to develop into many different types of cells in the body. They work as an internal repair system. They divide without limit in a living multicellular organism to replenish the other cells. Each stem cell has a potential to retain its quality as a stem cell or they become specialized cells – called as pluripotent cell – to do a specialized function.

They have two important characteristics. These characteristics distinguish stem cells from other cells. The two important characteristics are:

  • Stem cells are capable of renewing themselves. Even after long periods of inactivity, they renew themselves through cell division. They self-renew themselves to produce more stem cells. A stem cell which is kept in a laboratory can replicate many times and yield millions of cells. Stem cells are capable of long-term-self-renewal.

 

  • Stem cells can be induced to become tissue or organ-specific cells and can be used to perform some special functions and serve as a muscle cell, a red blood cell, or a brain cell. When induced, they repair and replace the worn out or damaged tissues, by dividing themselves.

 

These stem cells are important for any living organisms. There are many reasons why they are important for a multicellular organism which is alive. In a blastocyst (3 to 5 day old embryo is known as blastocyst) stem cells help develop the entire body of the organism which includes specialized cell types and organs such as the heart, lung, skin, sperm, eggs and other tissues. They also replace cells that are lost because of usual wear and tear.

Stem cells are taken from numerous sources like umbilical cord blood and bone marrow. Stems cells are now artificially grown and then they are transformed into specialized cell types. These artificially grown stem cells have the same characteristics as stem cells. The transformation is done through cell culture.

Stem cells are used in medical therapies. These therapies are known as regenerative or reparative medicine. They are also known as cell-based therapies. With their regenerative abilities, stem cells can be used to treat diabetes and heart disease.

So far, researches have been done primarily on two kinds of stem cells from animals and human. They are :

  • Embryonic stem cells and
  • Non-embryonic or adult stem cells.

With the ongoing studies of stem cells in the laboratories, scientists are able to learn about the essential properties of stem cells and the reason about their unique characteristics. Scientists are using stem cells to screen new drugs. They are trying to develop model systems to study normal growth and identify the causes of birth defects.

Research on stem cells reveals new findings about how a multi organism develops from a single cell and how a damaged cell is replaced with a healthy cell in adult organisms.

No doubt, stem cell research is the most fascinating one in the contemporary biology. But just like any other new discovery, there are many scientific questions to be answered about stem cells.

What are embryonic stem cells?

Stem cells derived from embryos are called embryonic stem cells. These stem cells are not derived from eggs fertilized in a woman’s body. But they are fertilized in an in vitro fertilization clinic. The derived embryonic stem cells are donated for research purposes.

The process of growing embryonic stem cells in a laboratory:

Embryonic stem cells are grown in the laboratory by a procedure known as cell culture.Human cells from a preimplantation-stage embryo are transferred into a plastic laboratory culture dish filled with a culture medium. This culture medium is a nutrient broth.

The culture dish is prepared first. The inner surface is coated with mouse skin cells. This coating is called as feeder layer.These cells are known as feeder cells because they release nutrient into the culture medium.The mouse skin cells are treated so that they don’t divide. This coating provides  a sticky surface for the cells to attach themselves to the culture dish.

When mouse skin cells are used there is a risk of viruses or other macromolecules be transmitted to the human cells. Researchers now grow embryonic stem cells without mouse feeder cells. This is a milestone in the advancement of the stem cell research.

When these cells survive and start dividing and multiplying, they fill the dish. Once there are enough crowds they are removed and placed into several fresh culture dishes. This is repeated numerous times and for many months. Once the cell line is established, the original cells generate millions of embryonic stem cells.  During this process, at any given point, cells can be frozen and shipped to other laboratories for further culture and experiments.

Various laboratory tests are conducted to identify embryonic stem cells. Scientists use a process called characterization to test the cells to determine whether they show the fundamental properties that make them embryonic stem cells.

  • By growing and sub-culturing  the stem cells over a longer period, scientists ensure that the cells are capable of long-term growth and they have the capability to self-renew themselves. Scientists very often check the culture through a microscope to make sure the cells are healthy and they stay undifferentiated. (unspecialized)
  • Scientists look out for transcription factors which are produced by undifferentiated cells. Transcription factors are very important to turn genes on and off at the right time. This is very important for the embryonic development and cell differentiation.
  • Scientists test the cells to determine whether they can be re-generate, or sub-cultured, after freezing, thawing and re-plating.

When the embryonic stem cells are grown in culture under right conditions, they remain undifferentiated. When they are allowed to form groups or embryonic bodies, they become specialized to form muscle cells, nerve cells and many other cell types.

Scientists are trying to direct the differentiation of embryonic stem cells into specific cells types. Once this is achieved these differentiated cells can be used to treat certain diseases like Parkinson’s disease, diabetes muscular dystrophy, heart disease and vision and hearing loss.