Stem Cells and Immortal Dna
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Our lives are determined by the choices that we make. With every decision, we are becoming more specific. However, if we don’t like who we’ve become, we can dedifferentiate and go back to our original free selves, and from that point, anything is possible. Our cells work in a similar way. Our adult stem cells produce cells that become more and more specific. These cells can dedifferentiate and go back to their stem-like qualities. Our stem cells are designed to help regenerate damaged tissue, however, they can be damaging in the long run. Immortal DNA errors can build up over time to cause cancer.
Stem cells were discovered on November 6 1998 by a Wisconsin University Professor, James Thompson (Stem Cell Now pg 1). An in vitro fertilization clinic provided him with embryos to study. At an embryos fifth day of development it’s referred to as a blastocyst and has approximately 100 to 300 cells (1). This embryo is just barely twice the diameter of a human hair. Using a thin glass needle, he was able to extract the blastocyst’s inner cell mass (Stem Cell Now pg 2). Our understandings of stem cells have come a long way since this original discovery.
For a time, contemporary science believed that stem cells had a few main qualities including: irreversible differentiation, self-renewal, and hierarchical development (3). It was believed that starting with a totipotent zygote, cell types would become more and more differentiated until they reached a very specific tissue (3). On their path, they would become pluripotential (can become any cell type), multipotent (more specific, but can only become a small range of similar tissue), and then finally a fully differentiated cell (3). This hierarchical development was studied in blood generating cells and believed to be true in regards to all stem cells (3).
Another distinct quality that stem cells are believed to have is self-renewal (3). Stem cells divide in an interesting way; they create two daughter cells, one of which is multipotent, and the other is another stem cell (4). The number of stem cells stays the same. It was believed that self-renewal was only available to stem cells (3). A recent article The Stem State: Plasticity is Essential calls this belief into question. According to research, irreversible differentiation, self-renewal, and hierarchical development are not necessary for a cell to be defined as a stem cell; all that is required is for that cell to have a quality referred to as plasticity (3). Plasticity is the ability of a cell to become undifferentiated and divide at a controlled rate; cancer is a mass of undifferentiated tissue that divides at an uncontrolled rate.
The Stem State: Plasticity is Essential argues that the hierarchical structure is optional and that progenitor cells (descendants that are differentiated) may enter the stem state even after they’ve completely differentiated (3). Adult stem cells have been found to be more than the multipotent cells that they are supposed to be. Skin progenitor cells can transform into muscle or nerve cells (3). The article argues that the main quality of stem cells is plasticity; they can transform into any cell (3).
The reason adult stem cells are in our bodies is to make any necessary repairs to tissue specific cells. Because of their immense importance, adult stem cells attempt to avoid DNA replication errors (5). With each stem cell division, the original parental version of DNA is kept instead of the newly synthesized one (5). Continuous adult stem cell division would put them at risk for cancer because of the overall addition of unrepaired DNA errors (5). When differentiated cells go about mitosis, there is random chromosome segregation (5). Adult stem cells keep the original parental DNA strand to avoid alterations; over time though, the Immortal DNA can begin to build up with errors (5). These errors can eventually result in cancer.
In the short run, this technique is very beneficial. However, in the long run, these Immortal DNA strands can cause cancerous problems. Blood and skin cells do not live long enough to accumulate errors so the hypothesis of Immortal DNA makes sense (4). Alterations can add up in the Immortal DNA strands and eventually cause problems like cancer (5). After many alterations in the eternal DNA, the stem cells can begin to produce cancerous cells. A few screwed up adult stem cells can run a tumor. This explains why cancer that has been completely destroyed comes back. The cancerous stem cells could survive and start up the cancerous growth again (4).
So far, cancerous stem cells have found to be the root of all cancers that have been screened (4). Cancerous stem cells have deranged DNA; they can’t regulate their numbers so growth gets out of control (4). In 1961 doctors attempted to take cancer from a patient and move it to