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benefits of obesity

"…It may happen that you dislike a thing which is good for you,

and it may be that you love a thing which is bad for you.

Allah knows, while you know not." Qur'an [Surah Baqara 2:216]

In America an obese (a fatty) person, in some cases is frowned upon. Majority of Americans dislike the human fat, which is scorned and despised and ruthlessly vacuumed from bellies and backsides by suction-assisted lipectomy (i.e., liposuction) may have a redeeming feature after all. This much-accused tissue appears to be a rich source of stem cells, prized by scientists for their seemingly magical power to turn into a variety of tissue types. These tissues can be replacements for almost any part of the human body without the problems of rejection. Rejection is a colossal problem currently in human organ transplants.

What are Stem Cells?

Stem cells are living cells that can develop into many different types of tissue, such as bone, muscle or brain. There are three basic types: (1) "Totipotent" stem cells These cells are formed when a fertilized egg first divides- can turn into any type of tissue and form a "total" organism. After five days after fertilization, a hollow ball of about 100 cells called a blastocyst forms. The cells on the outside develop into the placenta, while those on the inside turn into the embryo itself. (2) The 50 or so inner cells are "pluripotent" - they can turn into almost all types of tissue, but not a whole organism. As the embryo develops further, stem cells become (3) "multipotent" - they can give rise only to specific kinds of cells. Totipotent and pluripotent cells are also known as adult stem cells.

What kind is useful?

If they had their way most physicians would go for pluripotent stem cells because these can give all the types of tissues one needs, but cannot turn into a whole human being.

From where to get them?

At present the only place to get them is from human embryos, which is the one reason why pro-life groups are so opposed to stem cell research. Three research groups around the world have found ways to grow potentially limitless supplies of pluripotent cells in the lab - but these did come from embryos in the first place. If a patient were given organs grown from somebody else's cells, the patient has to take immunosuppressant drugs for the rest of his or her life.

Obtaining stem cells-primitive cells with the potential to become virtually any type of tissue-from adipose tissue or fat collected by liposuction - a cosmetic procedure - and converted them into becoming muscle, bone or cartilage, depending on the conditions in which they were grown, scientists, reported in the journal Tissue Engineering (Volume 7, Number 2: 211-218, April 2001). This article titled "Multilineage cells from human adipose tissue: implications for cell-based therapies, was authored by Zuk PA, Zhu M, Mizuno H, Huang J, Futrell JW, Katz AJ, Benhaim P, Lorenz HP, Hedrick MH of the Laboratory for Regenerative Bioengineering and Repair, Department of Surgery and Orthopaedic Surgery, UCLA School of Medicine, Los Angeles, California. Tissue Engineering is the application of the principles of life sciences and engineering to develop biological substitutes for the restoration or replacement of tissue or organ function.

Stem Cells are undifferentiated cells in an embryo or adult which can undergo unlimited division and give rise to one or several different cell types. In adults an undifferentiated cell from which some renewable tissues (blood, skin, etc. ) are formed.

Human adipose tissue (fat) obtained by suction-assisted lipectomy (i.e. liposuction) was processed to obtain a fibroblast-like population of cells or a processed lipoaspirate (PLA). These PLA cells can be maintained in vitro (outside the body) for extended periods with stable population doubling and low levels of senescence. Immunofluorescence and flow cytometry show that the majority of PLA cells are mesodermal or mesenchymal origin with low levels of contaminating pericytes, endothelial cells, and smooth muscle cells. Finally, PLA cells differentiate in vitro into adipogenic (fat), chondrogenic (cartilage), myogenic (muscle), and osteogenic (bone) cells in the presence of lineage-specific induction factors. This pioneering study concludes that the data support the hypothesis that a human lipoaspirate contains multipotent cells and may represent an alternative stem cells source to bone marrow-derived MSCs (mesenchymal stem cells).

The discovery means that a person's own fat might one day be used to provide the tissue needed to treat disease or repair injured or worn-out parts. From cartilage implants in damaged knees to brain implants for Parkinson's disease and strokes. Theoretically, people might be able to get rid of their love handles while supplying the material needed to fix a creaky knee or hip. Unlike a transplant, tissue created by a person's owns stem cells would pose no risk of rejection or exposure to viruses from a donor.

"Fat may be a practical source of cells from which to make new tissues," said Dr. Marc H. Hedrick, the lead author and an assistant professor of surgery and pediatrics at the university of California at Los Angeles and the director of the study, in which researchers from the University of Pittsburgh collaborated. "We don't yet know the limits for stem cells found in fat," said Dr. Adam J. Katz of the University of Pittsburgh, a co-author. " So far, we have seen promising results with all of the tissue types we have examined." The Bush administration is contemplating to ban the use of embryonic stem cells from aborted tissues, and hence this new discovery offers an alternative source that could be much more abundant and much less contentious. "This could take the air right out of the debate about embryonic stem cells," said Dr. Hedrick. The newly identified cells have so many different potential applications, he added, that "it makes it hard to argue that we should use embryonic cells." "This changes the way we think about fat tissue," Dr. Hedrick said. "It's not a static spare tire around our waist. It 's really a dynamic tissue, and there are a lot of things in it that could help us fix people with diseases." (NY Times April 10, 2001).

"This is extremely significant in terms of its potential," said Dr. Michael T. Longaker of Stanford University. "Unfortunately, fat is a substantial natural resource in the USA. This is a great way to do something with it." (The Courier-Journal, Louisville, KY April 10, 2001)

During the 1990s, researchers have found that adults also have stem cells in a variety of locations, ranging from bone marrow, to the brain. Since they are present in small numbers and recovering them could be difficult and painful. Small amounts of stem cells can be extracted from bone marrow, but removing marrow from a patient can be painful. For example to extract stem cells from the bone marrow requires drilling a tiny hole directly in the bone, which remains painful for weeks after the procedure. Furthermore the yield is small, usually about a few milliliters (ml). Stem cells for research has been collected from bone marrow, brain or fetal tissue. But the use of fetal tissue has provoked ethics disputes, and performing brain surgery to harvest stem cells is not practical.

On the other hand Liposuction is much easier to perform through an incision in the skin that about one inch long and is relatively painless. And liters of fat is harvested and tossed away-producing a thousand times as many stem cells as can be obtained from bone marrow. In older adults, the percentage of stem cells is even higher in fat cells than in bone marrow. Since each person serves as his or own fat donor, there would be no problem with rejection of implanted cells. Researchers looked for stem cells in fat because fat, marrow and bone in humans developed from the same layer of embryonic tissue, the mesoderm, and tissues from the same origin often had properties in common. So if bone marrow has stem cells, then it is logical to think that fat should have them too. The researchers saved fat from liposuction and processed it to isolate cells thought to include stem cells. To get things revved up, the cells have to be fed with the right stuff.

To coax the cells to make bone, for instance, the researchers used a medium containing calcium, phosphate and vitamin C. They varied the conditions to grow cartilage, muscle or more fat cells. Stem cells can be converted into specific tissues by exposing them to complex mixture of growth hormones and other chemicals, which requires a different formula for each desired tissue. The bottom line is finding what needs to be included in each formulation.

The study was the first to find stem cells in fat and use them to grow different tissues. Like any other study, other researchers to find out whether the conclusions hold up must repeat it. Another team at Duke University has produced similar results, turning stem cells from fat into cartilage. "It's very important for different groups to reach the same conclusion with a study with this much potential impact," said Dr. Farshid Guilak, leader of the Duke study. Both the Stanford and Duke groups are executing tissue examinations in animals, and both suggested that for the first clinical trials to be conducted in humans, it may take up to five years. Repairing of knees and other joints, as well as noses and ears by cartilage implants will be the initial utilization of this discovery. Laboratory grown Cartilage cells are being used in the reconstruction of damaged knees, but the use of stem cells would astoundingly increase the supply of tissue available. The organs and tissues that resist healing such as broken and impaired bones could be repaired. This item is also high on the agenda. The stem cells might be used for a much extensive diversity of applications, including brain implants for Parkinson's disease and strokes (brain attacks), and in the repair of heart tissues, are all possibilities in the future. Now, embryonic stem cells that secrete vital hormones are used to treat victims of Parkinson's and Huntington's diseases, for example.

In the adult human body most of the cells are somatic cells. These somatic cells are called differentiated cells and have adopted an indelible identity- skin, heart, muscle, whatever the case and they cannot be changed. Skin cells, for example, cannot be converted into bone, cartilage or brain tissue, or vice versa. But embryos have a large percentage of genetically unprogrammed or undifferentiated cells that have the potential to become any kind of cell in the body. All other cells stem from these undifferentiated cells, hence the name stem cells them. The stem cells are a premium for researchers and clinicians, but their use is highly disputed because the only way to obtain them is through a miscarriage.

Even if they do, using fat to provide tissue for patients is a long way off and a procedure for doing so is not clear. Scientists must determine, for instance, whether stem cells can be given to patients or whether the cells must be cultured in the laboratory to turn them into the desired tissue, then implanted where needed. Actual tests involving humans are likely five years away.

Posted by: weena zab Posts: 7 :: 28-02-2008 :: | Reply to this Message

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