One tissue engineering device is the Bioartificial Liver Device (BAL). There are two BAL's currently in clinical trials, they are the HepatAssist 2000 and the ELAD. The aim of both of these devices is either as a bridge to transplant, or as a means of letting the liver regenerate on it's own. Both perform these tasks rather well, but both differ in the method used to do this.
The HepatAssist 2000 is an extracorporeal device with hollow tubes and pig liver tissue samples that filters the plasma. This is good as plasma has a better flow rate, there is a greater molecular transfer rate, and there is decreased intracranial pressure. The down side is that pig cells create pig proteins which may cause immune responses, the plasma separation process can also cause problems.
The ELAD uses filtration cartridges much like kidney dialysis. These tubes contained hollow fibers with cloned human cells that are cultured in them. The ELAD is good as it mimics many of the natural liver functions like metabolizing amino acids and producing proteins and clotting factors. The down side of this product could be the fact that it doesn't have the better flow rates that the HepatAssist 2000 has.
http://www.medscape.com/viewarticle/420583
Wednesday, July 30, 2008
Gene Therapy
Genes, which are carried on chromosomes, are the basic physical and functional units of heredity. Genes are specific sequences of bases that encode instructions on how to make proteins. Although genes get a lot of attention, it’s the proteins that perform most life functions and even make up the majority of cellular structures. When genes are altered so that the encoded proteins are unable to carry out their normal functions, genetic disorders can result. Gene therapy is a technique for correcting defective genes responsible for disease development. Researchers use several approaches for correcting faulty genes including:
· inserting a normal gene into a nonspecific location within the genome to replace a nonfunctional gene
· swapping an abnormal gene for a normal gene through homologous recombination
· repairing the abnormal gene through selective reverse mutation
In most gene therapy studies, a "normal" gene is inserted into the genome to replace an "abnormal," disease-causing gene. A carrier molecule called a vector must be used to deliver the therapeutic gene to the patient's target cells. Currently, the most common vector is a virus that has been genetically altered to carry normal human DNA. Viruses have evolved a way of encapsulating and delivering their genes to human cells in a pathogenic manner. Scientists have tried to take advantage of this capability and manipulate the virus genome to remove disease-causing genes and insert therapeutic genes.
· inserting a normal gene into a nonspecific location within the genome to replace a nonfunctional gene
· swapping an abnormal gene for a normal gene through homologous recombination
· repairing the abnormal gene through selective reverse mutation
In most gene therapy studies, a "normal" gene is inserted into the genome to replace an "abnormal," disease-causing gene. A carrier molecule called a vector must be used to deliver the therapeutic gene to the patient's target cells. Currently, the most common vector is a virus that has been genetically altered to carry normal human DNA. Viruses have evolved a way of encapsulating and delivering their genes to human cells in a pathogenic manner. Scientists have tried to take advantage of this capability and manipulate the virus genome to remove disease-causing genes and insert therapeutic genes.
Stem Cells to Cure Parkinson's
Scientists have been working with stem cells since the 1980s, continuously searching to find functional benefits of the relatively new technology. In 2007 and article, “Stem Cells Make Neurons, and Tumors, in Rate Model of Parkinson’s Disease,” was released stating that “human embryonic stem cells led to dramatic functional improvement” although it was also shown to cause brain tumors. Research was done to determine whether stem cells could help cure Parkinson’s disease (PD). PD causes muscles to stiffen and a person’s movement to slow. It is believed that stem cells could help PD because it is a disease that damages few neurons which produce dopamine.
An experiment performed by Steven Goldman, M.D., Ph.D., at the University of Rochester Medical Center described how the stem cells were induced to become dopamine producing neurons. The cells were placed in rats with a condition similar to PD and the rats recovered their mobile functions. Along with the recovery, however, a tiny amount of the implanted cells had formed tumors. Stem cells had been produced in the past that showed therapeutic effects for PD, but the study was the first to show that cells derived from humans are able to produce positive effects as well as those cells derived from animals.
The study was continued with the use of a toxin that destroyed dopamine producing neurons being implanted into rats before any problems with movement existed. The rats were treated with the stem cells and showed to perform as well as rats that had not received the toxin within a few months. Dr. Goldman believes that all the team needs to do it find a way “‘to purify the neurons and separated them from the undifferentiated cells.’” The results from Dr. Goldman’s experiment are promising despite the fact that some tumors had formed on a few cells. The field of stem cell therapeutics is rapidly growing.
http://www.ninds.nih.gov/news_and_events/news_articles/stem_cells_improve_PD.htm
An experiment performed by Steven Goldman, M.D., Ph.D., at the University of Rochester Medical Center described how the stem cells were induced to become dopamine producing neurons. The cells were placed in rats with a condition similar to PD and the rats recovered their mobile functions. Along with the recovery, however, a tiny amount of the implanted cells had formed tumors. Stem cells had been produced in the past that showed therapeutic effects for PD, but the study was the first to show that cells derived from humans are able to produce positive effects as well as those cells derived from animals.
The study was continued with the use of a toxin that destroyed dopamine producing neurons being implanted into rats before any problems with movement existed. The rats were treated with the stem cells and showed to perform as well as rats that had not received the toxin within a few months. Dr. Goldman believes that all the team needs to do it find a way “‘to purify the neurons and separated them from the undifferentiated cells.’” The results from Dr. Goldman’s experiment are promising despite the fact that some tumors had formed on a few cells. The field of stem cell therapeutics is rapidly growing.
http://www.ninds.nih.gov/news_and_events/news_articles/stem_cells_improve_PD.htm
Artificial Blood Vessels
Artificial blood vessels were first introduced during WWI when Alexis Carrel discovered a way to sew blood vessels together. Today, methods from the 1940s and 1950s are still used. Surgeons originally used transplants for arteries or veins. However, this method resulted in failure. The recipient’s body either rejected the vessels or arteriosclerosis (artery hardening) formed. To transplant vessels from the same body required two complicated surgeries and most patients with circulatory problems did not have vessels for transplantation.
Researchers began to develop artificial vessels to overcome this problem. Tubing materials included polyethylene (soft and waxy plastic) and siliconized rubber. Further research proved that vessels made from Teflon and Dacron were not rejected by the body. While the larger Dacron vessels worked well, the smaller ones formulated blood clots. Smoother interior walls would help prevent clots from forming.
In the 1980s, Donald Lyman synthesized a polymer that reduced clot formation. The elastic polymer also reduced the strain where the natural and artificial valves met. Human testing began in 1988. In 1990, the bio-research company Organogenesis implanted a hybrid vessel in animals made of natural and artificial materials. This artificial vessel features a smooth inner layer grown in the laboratory from human cadaver (dead body) artery cells and tubules strengthened with Dacron mesh. Stuart Williams at Jefferson Medical College, Philadelphia, Pennsylvania, uses cells from the patient's own inner blood vessel lining to grow a lining on the inside of Dacron synthetic vessels.
Researchers have already managed to make wider blood vessels from scratch, but the formation of the tiny diameter capillaries needed to create a blood supply within other tissues and organs is more challenging. However, through the “nanoscale” template, US scientists claim to have made progress using stem cells using endothelial progenitor. These cells detect the grooves and align themselves in the direction of the vessel. When a gel is added, the cells grow outward consequently forming tiny tubes. Even though these tubes are not ready to be placed inside the body, researchers cannot contain their enthusiasm for the potential results of this process.
http://www.discoveriesinmedicine.com/Apg-Ban/Artificial-Blood-Vessels.html
http://news.bbc.co.uk/2/hi/health/7152405.stm
Researchers began to develop artificial vessels to overcome this problem. Tubing materials included polyethylene (soft and waxy plastic) and siliconized rubber. Further research proved that vessels made from Teflon and Dacron were not rejected by the body. While the larger Dacron vessels worked well, the smaller ones formulated blood clots. Smoother interior walls would help prevent clots from forming.
In the 1980s, Donald Lyman synthesized a polymer that reduced clot formation. The elastic polymer also reduced the strain where the natural and artificial valves met. Human testing began in 1988. In 1990, the bio-research company Organogenesis implanted a hybrid vessel in animals made of natural and artificial materials. This artificial vessel features a smooth inner layer grown in the laboratory from human cadaver (dead body) artery cells and tubules strengthened with Dacron mesh. Stuart Williams at Jefferson Medical College, Philadelphia, Pennsylvania, uses cells from the patient's own inner blood vessel lining to grow a lining on the inside of Dacron synthetic vessels.
Researchers have already managed to make wider blood vessels from scratch, but the formation of the tiny diameter capillaries needed to create a blood supply within other tissues and organs is more challenging. However, through the “nanoscale” template, US scientists claim to have made progress using stem cells using endothelial progenitor. These cells detect the grooves and align themselves in the direction of the vessel. When a gel is added, the cells grow outward consequently forming tiny tubes. Even though these tubes are not ready to be placed inside the body, researchers cannot contain their enthusiasm for the potential results of this process.
http://www.discoveriesinmedicine.com/Apg-Ban/Artificial-Blood-Vessels.html
http://news.bbc.co.uk/2/hi/health/7152405.stm
Use of Gene Therapy for Dwarfism
Alexis Gorin
Farah Laiwalla
Engineering Biomedical Systems (BI920-3B)
Wednesday, July 30, 2008
To treat dwarfism, the condition of abnormally-caused small stature, doctors use gene therapy as an option to help people affected, using growth hormone and any other hormone the person may be missing. The amount of each type of hormone given constantly changes though due to (metabolic) changes within the child (1).
Different drug deliveries systems are used to get the growth hormone in the body systems. One way, used by doctors like Jeffery M. Leiden, is to remove muscle cells and place the gene that makes HGH inside the cells, only to be placed back inside the body (2). This method has become very effective since new research came out, proving that muscle cells can secrete proteins. The study shows that after three months, the mice the manipulated muscle cells were put in were still making HGH.
Another way to deliver the needed hormones, although can be used for other purposes, is to put the hormone-creating gene into "replication-deficient retrovirus" (3). The virus then can attach to muscle cells and has its host cell copy the hormone-creating genetic material, have the material build up, and then spread to other cells. This was created by Vandenburgh as a way to deal without constant injections of proteins.
(1) "Dwarfism." Free Health Encyclopedia. 2007. NetIndustries, LLC. . 30 Jul 2008 http://www.faqs.org/health/topics/99/Dwarfism.html.
(2) Angier, Natalie. "With Direct Injections, Gene Therapy Takes A Step Into a New Age ." The New York Times 14 April 1992 30 Jul 2008 http://query.nytimes.com/gst/fullpage.html?res=9E0CE6DB1E3BF937A25757C0A964958260&sec=&spon=&pagewanted=all.
(3) "Gene Therapy - Putting Muscle Into the Research." NASA. 06 June 2002. NASA. 30 Jul 2008 http://www.nasa.gov/vision/earth/livingthings/gene_therapy_prt.htm.
Farah Laiwalla
Engineering Biomedical Systems (BI920-3B)
Wednesday, July 30, 2008
To treat dwarfism, the condition of abnormally-caused small stature, doctors use gene therapy as an option to help people affected, using growth hormone and any other hormone the person may be missing. The amount of each type of hormone given constantly changes though due to (metabolic) changes within the child (1).
Different drug deliveries systems are used to get the growth hormone in the body systems. One way, used by doctors like Jeffery M. Leiden, is to remove muscle cells and place the gene that makes HGH inside the cells, only to be placed back inside the body (2). This method has become very effective since new research came out, proving that muscle cells can secrete proteins. The study shows that after three months, the mice the manipulated muscle cells were put in were still making HGH.
Another way to deliver the needed hormones, although can be used for other purposes, is to put the hormone-creating gene into "replication-deficient retrovirus" (3). The virus then can attach to muscle cells and has its host cell copy the hormone-creating genetic material, have the material build up, and then spread to other cells. This was created by Vandenburgh as a way to deal without constant injections of proteins.
(1) "Dwarfism." Free Health Encyclopedia. 2007. NetIndustries, LLC. . 30 Jul 2008 http://www.faqs.org/health/topics/99/Dwarfism.html.
(2) Angier, Natalie. "With Direct Injections, Gene Therapy Takes A Step Into a New Age ." The New York Times 14 April 1992 30 Jul 2008 http://query.nytimes.com/gst/fullpage.html?res=9E0CE6DB1E3BF937A25757C0A964958260&sec=&spon=&pagewanted=all.
(3) "Gene Therapy - Putting Muscle Into the Research." NASA. 06 June 2002. NASA. 30 Jul 2008 http://www.nasa.gov/vision/earth/livingthings/gene_therapy_prt.htm.
Bone Scaffolds
Marissa Reitsma
7/30/08
Bone Scaffolds
http://www.acfnewsource.org/science/bone_scaffold.html
http://www.rsc.org/Publishing/Journals/cb/Volume/2007/1/Bone-buildingscaffold.asp
Stem Cell application
A stem cell is a kind of cell produced in a four-five day old fetus, called a blastocyst, which hasn't been assigned a specific purpose in the body yet. This "unassigned" cell allows researchers to implant stem cells into dying patients to improve impaired body parts and organs. Stem cell applications, whether embryonic, adult or pluripotent, is a huge breakthrough in modern-day scientific research. For scientists, stem cells are very vital to understanding how the body works and how to improve certain body tissues and cells. As of now, the goverment is not funding adequate amounts of money to pave the way for uses for stem cells, due to ethical problems. Yet, researchers have found that stem cells can help with numerous diseases and illnesses, ranging from cancer to a "broken heart" to glaucoma.
Stem cells can be transplanted into a patient, therefore completely eliminating the problem of a non-working body organ. Stem cells can also fix chromosomal abnormalities at birth.
Stem cells can be transplanted into a patient, therefore completely eliminating the problem of a non-working body organ. Stem cells can also fix chromosomal abnormalities at birth.
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