Stem cells are considered to be the building cells of the body. All other sections are produced from these raw cells, which perform many specialized functions in the body. Stem cells can divide, whether in vitro (laboratory) or in vivo (body), and they produce more cells called the daughter cells. The newly split cells can either develop into new stem cells or become differentiated, specialized cells that perform definite functions. These specialized cells include brain cells, blood cells, and bone or heart muscle. The only cells with stem cells are those with stem cells potential to be able to generating new cell types; no other cell in the body can do so.
Several sources of stem cells have been discovered over time. The first source is embryonic stem cells, which appear from very naïve embryos that are just three to six days old. At this phase, the cells are said to be pluripotent stem cells, meaning they know how to become any new cell form of body or can divide into new stem cells. This quality makes them able to help scientists find new ways to repair diseased tissues (Gersh, 2009). The second source is adult stem cells present in most adult tissues in small numbers, for example, in fat cells or bone marrow. Mature stem cells have an inadequate ability to generate different cells in the body, unlike embryonic stem cells. The thing that is fascinating about the adult stem cells is that they can create unrelated cell types. For example, bone marrow stem cells might generate heart muscle cells, negating the fact that stem cells of bone marrow can only produce blood cells. Using genetic reprogramming, Scientists have now successfully experimented with transforming adult stem cells into stem cells. This new development has helped researchers to make use of these genetically reprogrammed cells as an alternative to embryonic stem cells. This will provide the edge by reducing the immune system's chances of negative response to the new stem cells. However, it is still unclear if changing adult cells will cause unfavorable effects in humans or not (Joo., 2012). Another source of stem cells has been discovered in amniotic fluid/ umbilical cord blood stem cells or prenatal stem cells. These cells also have the aptitude to modify themselves into specialized cells. It also helps conduct a test for fetus abnormalities by taking the sample from stem cells of amniotic fluid in the uterus.
Lung diseases have become very common nowadays. There are four kinds of lung diseases. Lung circulation diseases occur when there is a problem with the lungs' blood vessels; it could be an inflammation of the blood vessel or a blood clot. It reduces the lung's ability to take up oxygen and release carbon dioxide. Airway disease of the lungs includes the blockade of tubes that carry oxygen to the lungs. It causes asthma, chronic bronchitis, and emphysema. Lung tissue diseases involve the defect in the structure of lung tissue. It limits the lungs' expansion, making the inflow of oxygen and outflow of carbon dioxide difficult. Pulmonary fibrosis and sarcoidosis are caused due to lung tissue defects. According to a WHO report, the mortality rate caused by chronic lung diseases has doubled in the last thirty years. The death rate of other chronic diseases is decreasing, making the situation even worse. The main reason behind this is the lack of concern about this disease and its unavailability. The absence of the diagnostic methods to cure these lung diseases is also a hallmark of increasing mortality rates.
Researchers have identified various methods to cure lung diseases using stem cells. The first is to use endogenous lung stem cells that take part in the repair and maintenance of injured lung epithelium (Evans MJ et al., 1978). The existing lung tissue stem cell therapy has been applied to rodents injury models in the laboratory before, in which cells were worn-out through physical or chemical means (Borthwick et al., 2001; Giangreco et al., 2002). After successful experiments, it was applied to humans. Recruited cells also made successes in lung repair and remodeling. Marrow-derived cells have the strong faculty to make a way to the lung's mesenchymal partition, curing the defects in those cells (Hashimoto et al., 2004). It is still uncertain, however, whether it is more beneficial or harmful to humans (Phillips et al., 2004). Some researchers have also worked on particular cells consequent from embryonic stem cells to cure lung diseases. Lung progenitor cells can be spawned in vitro by differentiation of embryonic stem cells that enhances its efficiency (Rippon et al., 2006).
Every day, the application of stem cells to treat diseases is growing. Embryonic stem cells, however, may trigger an immune response that causes the recipient's body to treat the stem cells as foreign invaders, as human embryonic stem cells are extracted from human embryos, leading to many ethical problems.
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