Almost all multicellular organisms are developed from the fertilized egg. No matter if you are a plant, worm, frog or human, principal is the same. After sperm and egg merge – a zygote is formed. Diploid cell divides, leading to the next stage - embryo formation. Subsequent gigantic morphological changes can last more or less (species specific) until new organism is fully developed and ready to be born.
Cell division is necessary to increase the number of cells that will form different tissues and organs. Approximate number of cells in adult human body is 100 trillion forming 200 different cell types. It’s hard to imagine that all cells share the same ancestor considering how different they look at the end. Despite intense divisions cells are undergoing, they remain the same with intact genetic material derived from their parents. Position cell hold in the early stage of embryonic development (inside three germ’s layer) will determine its future destiny. Cells lying in the endoderm will become part of the digestive or respiratory system; cells in mesoderm – part of the muscle or bones and cells in ectoderm – part of nervous or integumentary system. Cell potency is crucial factor for differentiation processes that are leading to the new organism formation. Totipotent cell is the one able to differentiate into every kind of cells that are present in developed multicellular organism. Pluripotent cell still have high potency and can give a rise to a lot of different cell types but can’t produce extraembryonic tissue. Multipotent cell have ability to form minor number of cell types and oligopotent cell even less. With each new division, cell is becoming more differentiated and less potent. Modifications in genetic expression are controlling whole process of cell division and their specialization.
Once cell is differentiated, it becomes ready to serve its purpose. Lifespan of the cells is determined by the role they play. Taste receptors are living 10-15 days; skin cells one month, red blood cells around 3 months, muscle cells almost 15 years and nervous cells are in our body for a lifetime. Multipotent cells are replacing old cells or cells that are destroyed accidently (traumatic events like broken bone or burned skin). All “replacements” in our body are made by mesenchymal, adipose, endothelial or dental pulp stem cells.
Ability of cells to divide and differentiate as necessary was well know fact even at the beginning of the last century, but technology had to develop more to enable us to exploit that characteristic completely.
Martin Evans is a scientist responsible for isolating embryonic cell our of the mouse embryo and for gene targeting technique development. Knockout mouse is animal lacking one or more genes and it’s used for experiments where specific roles of the genes are investigated. He won a Nobel Prize for the contribution to the medicine and physiology.
Besides being useful for genetic experiments, stem cells become inevitable in therapy of various illnesses. The most used and famous stem cell associated therapy is bone marrow transplantation. It’s used for treatment of leukemia and lymphoma. Other promising therapies included brain and spinal cord injuries, intra cranial tumors, myocardial infarction, baldness, blindness and visual impairments, deafness, diabetes, neural and birth defects, wound healing, infertility…
Stem cells could be used for the animal treatments and they are especially effective for cardiac and musculoskeletal disorders.
Since stem cell therapy is one of the most promising future treatments, people are able to isolate and cryopreserve stem cells of their offspring by collecting samples of amniotic fluid (amniocentesis) during the pregnancy or out of the umbilical cord blood after the birth. Using specific techniques those cells are frozen and cryopreserved by liquid nitrogen. That way, cells are kept alive and ready for use the minute they are needed.
Another way to produce necessary amount of stem cells is to multiply them artificially. Those techniques are used in regenerative medicine, where cells, tissues or organs are replaced with laboratory grown implants. This type of healing can be faster and safer than waiting for organ donation. Also, that could solve the problem of immune response that is happening every time foreign organ is implanted. If patient himself donates cells for laboratory cultivation, transplant rejection will be avoided as body will recognize replaced tissue/organ as his own.
Therapeutic application of the stem cells is endless. Those are our cells and they “know” how to repair what need to be repaired once they are in the hotspot of the disease. Make sure to preserve your offspring’s stem cells – you never know when you going to need them.