Genetic cloning
Genetic cloning ----Genetic scientists have been busy creating all kinds of solutions to some of the problems that the human and agricultural populations have been experiencing. One of the most promising has been in the area of transplantation. That is how Dolly the sheep, came about. Scientists have been trying to find a way to genetically engineer animals so that they can produce organs for humans that will not be rejected. Insulin from pigs has helped diabetics, pig valves can be used in cardiac repair, and pig skin helps burn victims,why not organs next ?
Pig 23 was genetically altered to incorporate human genes, in hopes of preventing rejection after transplantation. Pigs have organs that are about the right size and are similiar to humans, also the availability of these organs is great due to the reproductive cycle of pigs. The biggest obstacle is the issue of rejection. The new organ is typically killed, even before the surgeon closes the incision, due to hyperacute rejection. This process clots the blood, by forming antibodies that attach to the endothelium of the blood vessels in the organ. The complement system creates gaps in vessels, allowing gaps to form and clots to accumulate. Therefore, a complement inhibitor was developed as the gene was cloned, introduced into pigs whose cells produced this protein. Another thing discovered, was that the cells lining the pig vessels have a sugar molecules called alpha-galactose, and humans have lots of antibodies against alpha-gal. Some are thinking of knocking out the gene for alpha-gal and replacing it with the human gene for type O blood sugar. One other stumbling block may be the transferense of unknown virus's like the HIV virus, that was somehow transmitted from monkeys. Scientists are hoping that most virus's will not be viable in humans.
Tissue engineering is a promising new field and livers are being grown in sponges, in hopes of providing livers to those whose livers have failed.
Transgeneic production is providing large quantities of drugs at lower costs through the milk of female offspring. One product thay are looking at producing is human serum albumin(HSA). Another product is recombinant human antithrombin III (Rh AT III), which competes with plasma-derived AT III, an anti-clotting drug, the former being produced in goats milk.
The company who cloned Dolly, has 147 sheep now, and is working on production of alph-1-antitrypsin (ATT) which is a cystic fibrosis treament. They have been given permission to expand their flock to 10,000 sheep to manufacture ATT. Polly has appeared now, carrying the gene for human blood factor IX. "Pharming" also produces Protein C in pigs milk, which is used during a stroke or heart attack. Another exciting development is the production of human fibrinogen, which controls bleeding and is being sprayed on shark bites, for example.
Inserting genes has been accomplished to produce human lactoferrin in cows milk, from a founder cow named Herman, who sired a lot of females, carrying this gene. Lactoferrin is used in...
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