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Stem Cell Research: Genetic Engineering

Introduction

Embryonic stem cells were first identified in the 1980s in animal models, and the breakthrough of their successful isolation from human embryonic tissue came after about two decades. They are derived from embryos that are in their initial stages of development. After an ovum is fertilized by a sperm, a zygote is formed, which then transforms into a loose clump of cells, called the morula, around the fourth day of embryonic development (Pearson, 60). Embryonic stem cells possess the property of pluripotency, which means that they can differentiate into all other cell lines except placenta and extra embryonic membranes, which are formed during embryonic development to support the embryo but are not needed after birth. Their growth is either initiated spontaneously or after the provision of appropriate environmental signals; they have been shown to have the highest potential for self—renewal and differentiation when compared with other sources such as germ, umbilical, and embryonic stem cells.Background

Scientists have also isolated cells with the potential of self—replication from the gonadal ridge—a part of the embryo that later produces eggs or sperm. These cells are called germ cells and are usually derived between week five and week nine of development (Merok, 24).

Although there have been concerns that embryonic stem cells may develop mutations, this may not be true unless they are forced to pass through more than 30 doublings—a practice that is not performed clinically (Pearson, 62).One of the properties of embryonic stem cells is that they can be derived from and later infused or transplanted back to the same individual, so the need for immunosuppression therapy can be avoided, whereas other sources of stem cells may still need immunosuppression therapy to avoid rejection and immune intolerance as a result of a mismatch between recipient and donor tissue (Gerald, 74).

The use of embryonic stem cells has been the topic of diverse debate and political activity since 2001, when President George W. Bush severely limited funding related to stem cell research. In 2006, legislators in a Republican—controlled Congress voted to expand stem cell research. The subsequent veto issued by President Bush in response was the first in his presidency (Merok, 25). In 2007 a Democratic—controlled Congress passed a bill to expand research, but the vote was not enough to override the June 20, 2007, presidential veto by President Bush. Congress was acting in response to the many citizens who could be potentially helped or cured by stem cell research developments. Researchers have viewed the process of cloning amniotic stem cells as a new process in studying genetic disease. This advancement would appear to be ethically neutral and nonthreatening to almost all political, special interest, and religious groups (Gerald, 76).Stem cell use could greatly expand the treatment options for children born with certain birth defects because these cells would be a direct genetic match to the fetus. Worldwide, an estimated 8 million children are born with a birth defect that is genetic or with a partially genetic—related birth defect. These ...