Stem cell

Some tiny cells can change.

These cells are very special. They can turn into many different things. They can become skin or blood.

They can also make bone or muscle. These cells help your body grow and fix itself. They can even make more of themselves. This helps your body stay healthy. It is amazing how they work!

Stem cells are special building blocks for living things.

Most cells have one job. But stem cells are different. They can change into many other types of cells. This is called differentiation. They can also make more of themselves. This way of making copies is called self-renewal.

There are different kinds of stem cells. Embryonic stem cells come from very early stages of growth. These cells are pluripotent. This means they can become almost any cell in the body.

Adult stem cells are found in small spots in the body. These are called niches. They help fix parts of the body that are lost quickly. For example, some help make new blood. Others help keep your skin healthy.

Scientists have studied these cells for a long time. In the 1960s, researchers found blood-forming stem cells in mice.

In 2006, a team in Japan found a new way. They turned mature body cells back into stem cells. These are called induced pluripotent stem cells. This discovery helps us learn how to treat many illnesses.

Stem cells are the special building blocks of all living things.

Most cells in your body have one specific job to do. However, stem cells are different because they are undifferentiated. This means they do not have a set job yet. They have a wonderful ability called potency. This is the power to change into many different types of cells. They also have a way to make more of themselves. This is called self-renewal, which helps a population of cells stay large.

There are two main ways these cells work in the body. First, embryonic stem cells come from the very early stages of growth. In mammals, these come from the inner cell mass of a blastocyst. This happens around days 5 to 14 of development. These cells are pluripotent, meaning they can become almost any cell in the body. They can turn into the three germ layers: the ectoderm, mesoderm, and endoderm.

Second, adult stem cells live in special spots called niches. These include places like bone marrow or the gonads. These cells are usually multipotent, so they only make a few types of cells.

Scientists have worked hard to understand these cells for many years. The names for these cells were first used in the late 19th century. In the 1960s, researchers Ernest McCulloch and James Till studied mice.

They found blood-forming stem cells by injecting bone marrow into mice. They saw lumps in the mice that came from a single cell. In 1956, Georges Mathé performed the first stem cell therapy. He used a bone marrow transplant to help workers in Yugoslavia. This was a very important moment for medicine.

Many important discoveries have happened since those early days. In 1981, biologists Martin Evans and Matthew Kaufman grew mouse stem cells. Later, in 1991, Ann Tsukamoto patented a way to isolate human stem cells. By 1998, James Thomson isolated human embryonic stem cells for the first time. In 2006, Shinya Yamanaka led a team in Japan. They found a way to turn mature body cells back into stem cells. These are called induced pluripotent stem cells, or iPSCs.

Stem cells help us understand how our own bodies grow and heal. For example, hematopoietic stem cells keep making your blood and immune cells. Other cells, called basal cells, help maintain your skin. Mesenchymal stem cells help look after your bone, muscle, and fat. Even wild animals can use them, like a maned wolf in 2011.

By studying how these cells work, scientists hope to find new ways to treat many different illnesses in the future.

Stem cells are unique building blocks in multicellular organisms. Most cells in a body have a specific job, such as carrying oxygen or sending signals. Stem cells are undifferentiated, meaning they do not have a set job yet. They possess two essential properties: self-renewal and potency. Self-renewal is the ability to divide many times while staying undifferentiated. Potency is the capacity to change into specialized cell types.

To maintain a population, stem cells use specific biological mechanisms. One method is asymmetric cell division. During this process, a stem cell divides into two different cells. One is a mother cell that remains an identical stem cell. The other is a daughter cell that becomes differentiated. This ensures the original stem cell population does not shrink. To protect their DNA during many divisions, stem cells use a protein called telomerase. This protein restores telomeres, which are the ends of DNA strands. This helps them bypass the Hayflick limit, which is the limit on how many times a cell can divide.

Scientists categorize stem cells by their level of potency. Totipotent cells are the most powerful. They can create a complete, viable organism, including the placenta. These come from the fusion of an egg and sperm. Pluripotent cells are descendants of totipotent cells. They can become nearly any cell in the body by forming three germ layers: the ectoderm, mesoderm, and endoderm.

Multipotent cells are more limited. They can only become a few types of cells within a related family. Oligopotent cells can only become a few specific types. Finally, unipotent cells can only produce one cell type, though they can still self-renew.

Embryonic stem cells (ESCs) provide a primary example of pluripotency. In mammals, these cells originate in the inner cell mass of a blastocyst. This stage occurs around days 5 to 14 of development. The inner cell mass contains roughly 50 to 150 cells. In a living body, these cells differentiate into the three germ layers. For example, part of the ectoderm becomes the neurectoderm. This eventually forms the central nervous system. This process involves neural stem cells becoming radial glial progenitor cells. These cells then undergo neurogenesis to create many different types of neurons.

Adult stem cells are found in different locations called niches. These include the bone marrow or the gonads. Unlike embryonic cells, adult stem cells are usually multipotent or unipotent. They exist to replenish cell types that are lost quickly. For instance, hematopoietic stem cells replenish blood and immune cells. Basal cells maintain the skin epithelium. Mesenchymal stem cells maintain bone, cartilage, muscle, and fat.

Adult stem cells are a small minority of total cells. They are vastly outnumbered by progenitor cells and terminally differentiated cells.

Our understanding of these cells grew from major scientific discoveries. The term "stem cell" was coined by Theodor Boveri and Valentin Haecker in the late 19th century. In the 1960s, Ernest McCulloch and James Till studied blood-forming stem cells in mice. They injected bone marrow into irradiated mice and saw lumps in the spleens. They hypothesized that each lump was a clone from one stem cell. They later confirmed this with Andrew J. Becker and Louis Siminovitch.

In 1956, Georges Mathé performed the first stem cell therapy. He used a bone marrow transplant to treat five workers in Yugoslavia. This was the first established medical therapy using stem cells.

Modern research has expanded these possibilities significantly. In 1981, Martin Evans and Matthew Kaufman successfully cultured mouse embryonic stem cells. In 1991, Ann Tsukamoto patented a process to isolate human stem cells. By 1998, James Thomson isolated human embryonic stem cells. This allowed for new ways to test treatments. However, isolating these cells is controversial because it often destroys the embryo. In 2006, Shinya Yamanaka's team in Japan discovered how to convert mature body cells back into stem cells. These are called induced pluripotent stem cells, or iPSCs.

This technology connects cell biology to advanced regenerative medicine.