Helping Cultured Stem Cells Roll

[drmithila]

Embryonic stem cells (ES cells) are pluripotent stem cells derived from the inner cell mass of the blastocyst, an early-stage embryo.[1] Human embryos reach the blastocyst stage 4–5 days post fertilization, at which time they consist of 50–150 cells. Isolating the embryoblast or inner cell mass (ICM) results in destruction of the fertilized human embryo, which raises ethical issues. Those issues include whether or not a human life at the embryonic stage should be granted the moral status of a human being as it is with a child or an adult.Safety: reducing the risk of teratoma and other cancers as a side effect

The major concern with the possible transplantation of ESC into patients as therapies is their ability to form tumors including teratoma.[20] Safety issues prompted the FDA to place a hold on the first ESC clinical trial however no tumors were observed.
The main strategy to enhance the safety of ESC for potential clinical use is to differentiate the ESC into specific cell types (e.g. neurons, muscle, liver cells) that have reduced or eliminated ability to cause tumors. Following differentiation, the cells are subjected to sorting by flow cytometry for further purification. ESC are predicted to be inherently safer than IPS cells because they are not genetically modified with genes such as c-Myc that are linked to cancer. Nonetheless, ESC express very high levels of the iPS inducing genes and these genes including Myc are essential for ESC self-renewal and pluripotency,[21] and potential strategies to improve safety by eliminating Myc expression are unlikely to preserve the cells’ "stemness"Embryonic stem cells have the potential to grow indefinitely in a laboratory environment and can differentiate into almost all types of bodily tissue. This makes embryonic stem cells a prospect for cellular therapies to treat a wide range of diseases.[18]
]Human potential and humanity
This argument often goes hand-in-hand with the utilitarian argument, and can be presented in several forms:
Embryos are not equivalent to human life while they are still incapable of surviving outside the womb (i.e. they only have the potential for life).
More than a third of zygotes do not implant after conception.[19][20] Thus, far more embryos are lost due to chance than are proposed to be used for embryonic stem cell research or treatments.
Blastocysts are a cluster of human cells that have not differentiated into distinct organ tissue; making cells of the inner cell mass no more "human" than a skin cell.[18]
Some parties contend that embryos are not humans, believing that the life of Homo sapiens only begins when the heartbeat develops, which is during the 5th week of pregnancy,[21] or when the brain begins developing activity, which has been detected at 54 days after conception.[22]
Efficiency
In vitro fertilization (IVF) generates large numbers of unused embryos (e.g. 70,000 in Australia alone).[18] Many of these thousands of IVF embryos are slated for destruction. Using them for scientific research uses a resource that would otherwise be wasted.[18]
While the destruction of human embryos is required to establish a stem cell line, no new embryos have to be destroyed to work with existing stem cell lines. It would be wasteful not to continue to make use of these cell lines as a resource.[18]
Abortions are legal in many countries and jurisdictions. The argument then follows that if these embryos are being destroyed anyway, why not use them for stem cell research or treatments?
Superiority
This is usually presented as a counter-argument to using adult stem cells as an alternative that doesn’t involve embryonic destruction.
Embryonic stem cells make up a significant proportion of a developing embryo, while adult stem cells exist as minor populations within a mature individual (e.g. in every 1,000 cells of the bone marrow, only 1 will be a usable stem cell). Thus, embryonic stem cells are likely to be easier to isolate and grow ex vivo than adult stem cells.[18]
Embryonic stem cells divide more rapidly than adult stem cells, potentially making it easier to generate large numbers of cells for therapeutic means. In contrast, adult stem cell might not divide fast enough to offer immediate treatment.[18]
Embryonic stem cells have greater plasticity, potentially allowing them to treat a wider range of diseases.[18]
Adult stem cells from the patient’s own body might not be effective in treatment of genetic disorders. Allogeneic embryonic stem cell transplantation (i.e. from a healthy donor) may be more practical in these cases than gene therapy of a patient’s own cell.[18]
DNA abnormalities found in adult stem cells that are caused by toxins and sunlight may make them poorly suited for treatment.[18]
Embryonic stem cells have been shown to be effective in treating heart damage in mice.[18]
Embryonic stem cells have the potential to cure chronic and degenerative diseases which current medicine has been unable to effectively treat.
Individuality
Before the primitive streak is formed when the embryo attaches to the uterus at approximately 14 days after fertilization, a single fertilized egg can split in two to form identical twins, or a pair of embryos that would have resulted in fraternal twins can fuse together and develop into one person (a tetragametic chimera). Since a fertilized egg has the potential to be two individuals or half of one, some believe it can only be considered a potential person, not an actual one. Those who subscribe to this belief then hold that destroying a blastocyst for embryonic stem cells is ethical.
]Viability
Viability is another standard under which embryos and fetuses have been regarded as human lives. In the United States, the 1973 Supreme Court case of Roe v. Wade concluded that viability determined the permissibility of abortions performed for reasons other than the protection of the woman’s health, defining viability as the point at which a fetus is "potentially able to live outside the mother’s womb, albeit with artificial aid."[24] The point of viability was 24 to 28 weeks when the case was decided and has since moved to about 22 weeks due to advancement in medical technology. Embryos used in medical research for stem cells are well below development that would enable viability.
Moral and ethical concerns
Many questions arise of this concern, Julian Savulescu [25] lists several arguments.
It is liable to abuse. It violates a person’s right to individuality, autonomy, self-hood. It allows eugenic selection.
His journal goes into details of the advantages of using stem cell lines mainly for therapeutic reasons with great emphasis on control. The main reason is that if this regeneration practice goes un-checked, there will be someone out there that will be "playing God."
Better alternatives"
This argument is used by opponents of embryonic destruction as well as researchers specializing in adult stem cell research.
Pro-life supporters often claim that the use of adult stem cells from sources such as umbilical cord blood has consistently produced more promising results than the use of embryonic stem cells.[26] Furthermore, adult stem cell research may be able to make greater advances if less money and resources were channeled into embryonic stem cell research.Embryonic stem cells have never produced therapies (to date, adult stem cells have been used in treatment). Moreover, there have been many advances in adult stem cell research, including a recent study where pluripotent adult stem cells were manufactured from differentiated fibroblast by the addition of specific transcription factors.Newly created stem cells were developed into an embryo and were integrated into newborn mouse tissues, analogous to the properties of embryonic stem cells.
This argument remains hotly debated on both sides. Those critical of embryonic stem cell research point to a current lack of practical treatments, while supporters argue that advances will come with more time and that breakthroughs cannot be predicted.