Stem Cells

Stem Cell

Stem cells are undifferentiated cells found in all multi cellular organisms with the potential to develop into many different types of cells in the body during early life and growth. In addition, they serve as a repair system for the body. When stem cells divide, each new cells have the potential either to remain their stem cells or become another type of cells with more specialized functions, such as muscle cells, red blood cells, or brain cells.

Commonly, there are two main types of stem cells:

1. Embryonic Stem Cells

Embryonic stem cells are pluripotent stem cells derived the inner cell mass of the blastocyst, an early-stage embryo.

In a developing embryo, stem cells can be different into all of the specialized embryonic tissues. The human embryonic stem cells each the blastocyst stage 4-5 days post fertilization; this stage is called as sexual reproduction, which begins when a male's sperm fertilizes a female's ovum to form a single cell called a zygote, and the zygote cell then begins a series of divisions. The blastocyst consists of an inner cell mass, embryoblast, which is the group of cells that will differentiate to become all the structures of an adult organism; and an outer cell mass, trophoblast, which becomes part of the placenta.

In a normal pregnancy, the blastocyst stage continues until implantation of the embryo in the uterus. This usually occurs by the 10th week of gestation after all major body's organs have been created. However, when extracting embryonic stem cells, the blastocyst stage signals when it isolates stem cells by placing the inner cell mass of the blastocyst into a culture dish. Lacking the necessary stimulation to differentiate, they begin to divide and replicate while maintaining their abilities to become any cell type in the body. Eventually, these undifferentiated cells can be stimulated to create specialized cells.

Derivation of Embryonic Cells from Human Fetal Tissue Embryonic Cells into Three Germ Layers

Embryonic Stem Cells Therapy

The Potential Uses of Embryonic Stem Cells

2. Adult Stem Cells

Adult stem cells are partially undifferentiated cells. They have been found inside the different types of organisms such as the brain, bone marrow, blood, blood vessels, skeletal muscles, skin, and the liver. These stem cells have two main characteristics. First, they make identical copies of themselves for long periods of time; this ability to proliferate is referred to as long-term self-renewal. Second, they can give rise to mature cell types that have characteristic morphologies, shapes, and speliazed functions.

Unlike embryonic stem cells, adult stem cells share no such definitive means of characterization. Adult stem cells exist throughout the human body after embryonic development. They can give rise to specialized cell types and usually derived from adult human blood located in the bone marrow and re-infused back into the same donor. However, Adult stem cells remain in a quiescent or non-dividing state for years until activated by disease or tissue injury.

Research on adult stem cells has generated a great deal of excitement. Scientists are discovering that adult stem cells are present in many more tissues than was at first thought and some are able to develop differences to other cell types. The finding has led researchers and clinicians to ask whether adult stem cells could be used for transplants. Now, scientists have evidence that stem cells exist in the brain and the heart. If the differentiation of adult stem cells can be controlled in the laboratory, these cells may be useful to treat some common serious diseases.

The Potential Uses of adult Stem Cells

The Potential Uses of Adult Stem Cells

Adult Stem Cells Differentiation

Adult Stem Cells Plasticity

Stem Cell Transplantation Successfully Treats

Therapy-resistant Chronic Leukemia, German Study Finds

by Stemness on 12. Jul, 2010 in Stem Cell News

ScienceDaily (July 12, 2010) -- The transplantation of stem cells from a healthy donor (allogeneic) offers the chance of cure for patients with an aggressive form of chronic lymphocytic leukemia (CLL), irrespective of genetic prognostic factors and the prior course of the disease. The German CLL Study Group proved this in a multicentric clinical phase II study led by Professor Dr. Peter Dreger, senior consultant and head of the division of stem cell transplantation at the Department of Internal Medicine V at Heidelberg University Hospital. The results were published online in the prominent journal Blood.

CLL is the most frequent form of leukemia in western countries. In many cases, it has a rather benign course. However, there are patients in whom the disease does not respond to the standard treatment with chemotherapy or antibodies. Patients with this high-risk CLL often die within a few years of the diagnosis. For some of these patients, the unfavorable course can be predicted based on the presence of typical chromosomal mutations in leukemia cells (deletion 17p-).

High-risk CLL can be controlled in the long term by allogeneic stem cell transplantation

Investigators at 16 different treatment centers in Germany included a total of 90 patients with high-risk CLL in the current study. For conditioning for transplantation, patients were given a reduced dosage of chemotherapy so that the acute tolerance of the transplantation was very good.

For a large percentage of patients, highly sensitive tests were conducted regularly to detect any remaining leukemia cells after the transplantation. In about half of these patients, no remaining CLL cells were detected in the blood in the long term, which was highly