Genetic Engineering in Cells and Tissues

Tissue engineering is the manipulation of artificial implants, laboratory-grown tissues, cells, or molecules to replace or suport the function of defective or injured body parts. Tissue engineering-related advances in a number of biomedical research fields--including cell culture, transplantation science, biomaterials research, bioengineering, and genetic engineering--are coming together in a way that promises to change the way medicine is practiced. Ultimately, the availability of laboratory-grown tissues may make traditional transplantation and reconstructive surgery obsolete, and may offer treatments for previously incurable diseases. (above information taken from http://www.dev.upmc.edu/Programs/Tissue/default.htm) Two products used in medicine that have been made (or made better) by genetic engineering of cells or tissues are human growth hormone and insulin. The genes to produce human growth hormone have been found, extracted, and put into microscopic organisms such as yeast or bacteria. Scientists then breed and "cultivate" the micro-organisms to produce human growth hormone. The human growth hormone is used for medical purposes. Because of our research on this topic most probably know the ethical issues related with the distribution of the product. The question is, who should have access to geneticly engineered human growth hormone? The hormone was made originally for children who lacked it and therefore were excessively short (midgets) but others wanted the product too. The bioethicist must decide who will benefit from this product and who really needs it, whether anyone who wants to be taller should be allowed to take the hormone or if it should be limited to those with medical problems causing excessive shortness. (above information taken from the Bioethics Symposium Course) Another product made by geneticly engineering cells or tissues is insulin. Insulin (a protein in all human beings) allows the body's cells to absorb sugar from the blood. When a nondiabetic eats, sugar begins to reach the bloodstream within minutes, causing cells in the pancreas to release insulin, which in turn brings down the sugar concentration. This precisely orchestrated feedback generally keeps blood sugar within 30% of its mean value. But diabetics lack this mechanism, either because their bodies are insensitive to insulin or utterly lacking in it. The 15 million or so diabetics in the U.S. with diminished sensitivity to insulin are often advised to inject insulin; the million-odd who lack native insulin must do so to live. One of the chief companies who produce this injected insulin is Eli Lilly. Before the product was available diabetics faced much grimmer life expectancies. In 1923 the company began to mass-produce the hormone from livestock animals. This was the first time an animal hormone was mass produced. The hormone certainly improved life for the diabetic but it was far from perfect. This was why, in 1982, the company became the first in the world to produce a human hormone geneticly engineered into bacteria. Since this product was real human growth hormone not animal growth hormone it worked much better. Thanks to the genetic engineering of this drug most diabetics can lead a fairly normal life. Recently Eli Lilly has improved its product again. Injected insulin, despite its benefits, still behaved slightly different from the stuff made in the pancreas. The insulin from the pancreas was distributed evenly but the injected insulin tended to form clumps in one place since insulin by nature is sticky. Scientists from the company found the amino acids (lysine and proline) that causing insulin to have its sticky property. By geneticly altering these amino acids the company was able to develop a "non-sticky" insulin. It will allow the diabetic to give him/herself a shot right before eating. Currently they must give themselves a shot an hour before eating. When the new geneticly engineered insulin is approved for use in America it will be a great benefit and convenience for those with diabetes. (information taken from Forbes magazine June 3, 1996)

Marc

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Genetic Engineering in Cells and Tissues