Various Types of Stem Cell

Many adult tissues contain stem cells that can replace cells that die or restore tissue after injury. Skin, muscle, intestine and bone marrow, each contain their own stem cells. It is not clear whether all organs such as the heart, contain stem cells. The term adult stem cell is often used very broadly and may include fetal and cord blood stem cells. There are a few stem cell therapies that are widely accepted by the medical community and these use tissue-specific stem cells. These are bone marrow or cord blood stem cell transplantation to treat diseases and conditions of the blood or to restore the blood system after treatment for specific cancers, skin stem cell therapies for burns and limbal stem cells for corneal replacement. The stem cells repair the same tissue from which they came in each case. Adult stem cells appear to have all the developmental potential of ES cells even though the precise mechanisms are debated without the risks of cancer. Skin stem cells occur in the basal layer of the epidermis and at the base of hair follicles. The epidermal stem cells give rise to keratinocytes which migrate to the surface of the skin and form a protective layer. The follicular stem cells can give rise to both the hair follicle and to the epidermis. Stem cells taken from a patient’s own blood have been found to regenerate heart muscle cells as well as artery tissue in the hearts of mice.

Fetal Stem Cells: Fetal stem cells are taken from the fetus. The developing baby is referred to as a fetus from approximately 10 weeks of gestation. Most tissues in a fetus contain stem cells that drive the rapid growth and development of the organs.

Cord Blood Stem Cells: At birth the blood in the umbilical cord is rich in blood-forming stem cells. The applications of cord blood are similar to those of adult bone marrow and are currently used to treat diseases and conditions of the blood or to restore the blood system after treatment for specific cancers.

Embryonic Stem Cells: Embryonic stem cells are derived from very early embryos and can in theory give rise to all cell types in the body. However, coaxing these cells to become a particular cell type in the laboratory is not trivial. Embryonic stem cells carry the risk of transforming into cancerous tissue after transplantation. To be used in cell transplant treatments the cells will most likely need to be directed into a more mature cell type both to be therapeutically effective and to minimize risk that cancers develop.

Induced Pluripotent Stem Cells : Scientists discovered how to “reprogram” cells with a specialized function in the laboratory so that they behave like an embryonic stem cell. These cells called induced pluripotent cells or iPS cells are created by inducing the specialized cells to express genes that are normally made in embryonic stem cells and that control how the cell functions. Embryonic stem cells and iPS cells share many characteristics, including the ability become the cells of all organs and tissues but they are not identical and can sometimes behave slightly differently. The techniques used to make them need to be carefully refined before they can be used to generate iPS cells suitable for safe and effective therapies.

Laws limiting the destruction of human embryos have been credited for being the reason for development of iPS cells but it is still not completely clear whether hiPS cells are equivalent to hES cells. It is also possible that these or similar cells modulate the immune system in response to injury.Stem cells that are pluripotent have the capability of forming virtually all the possible tissue types found in human beings.