Adult Stem Cells Advantages

unduhan-25Stem cell research is one of the most talked-about fields in modern medicine. It’s also one of the most misunderstood. Many people associate it with only embryonic stem cells, which are a source of much ethical debate, but there’s actually an entire world of data and inquiry that involves adult stem cells, which are found in our own bodies and may hold the key to treating some important health conditions.

Recent headlines, for example, have touted “major breakthroughs” in adult stem cell science and cardiovascular disease, and a number of high-profile celebrities, politicians, and athletes have undergone experimental stem cell treatments for pain and nerve damage. As more and more people seek out information about these procedures, here’s what you need to know.

Adult Stem Cells vs. Embryonic Stem Cells

Compared with the field of embryonic stem cell research, adult stem cell research is relatively new territory. For a long time, the medical community was interested primarily in embryonic stem cells, which are pluripotent, meaning they have the potential to generate any one of the 200 other cell types in the human body. Adult stem cells, conversely, are thought to be limited to forming types of cells based on their tissue of origin. For example, hematopoietic stem cells, found in bone marrow, give rise to blood cells, while adipose-derived stem cells, found in fat, give rise to adipocyte (fat) cells. Recent research has suggested that some types of stem cells may be able to transform into other cells via a process called transdifferentiation, but data – and scientific opinion – is mixed on this point.

Moreover, says Donald Kohn, MD, a scientist with the Broad Stem Cell Research Center at UCLA, “adult stem cells in general don’t have the ability to make more of themselves. When we take them from, say, the bone marrow, we can’t make more of them. The number we get out of the body is the most we have, and by the time we give them back [as in a transplant], we have less.” This, along with the fact that adult cells can be difficult to isolate from tissue, made pluripotent embryonic stem cells initially more compelling to researchers.

In recent years, however, scientists have shifted some of the focus to adult stem cells, partly out of necessity – federal and state legislation restricts funding for projects involving the creation, treatment, or destruction of embryos for research purposes – and partly because of new discoveries about the benefits of adult cells.

For one thing, Kohn says, there may be less risk of rejection with adult stem cells, since they’re often autologous, meaning they come from a person’s own body. “Embryonic stem cells don’t match your patient,” he explains. There’s a risk, as with any transplant, that the body won’t accept them.

Second, adult stem cells are readily available to everyone. We all have them inside of us – in our organs, bone marrow, blood, fat, etc. – so there’s a built-in (though limited) supply of donor material that matches our genetic makeup.

Finally, and perhaps most notably, adult stem cells don’t present the same ethical issues associated with embryonic stem cells, which, when harvested, result in the destruction of the embryo – a point of much controversy and debate in the medical, political, and religious sectors. Adult stem cells sidestep this problem because there’s no loss of human or potential human life.

Stem Cell Procedures in the News

Which is not to say, however, that adult stem cell research is immune to controversy.

Earlier this year, in July, Texas governor and Republican presidential hopeful Rick Perry raised some eyebrows – and red flags – when he underwent an experimental stem cell procedure to fuse part of his spine. The treatment, which was done outside of an approved clinical trial, involved liposuctioning fat from Perry’s body, separating and re-growing the stem cells from that fat, and then reinjecting the cells into Perry’s back and bloodstream in the hopes that they would form bone or cartilage. At the time, experts in the field balked at Perry’s decision to have the procedure, saying there was no scientific evidence to support its effectiveness – or, more importantly, its safety – and that by choosing to pursue an untested treatment, the politician risked blood clots, infection, even cancer cell growth.

“[Perry] went far outside mainstream medicine to treat his bad back – an irresponsible choice that endangered himself and anyone who might follow his lead,” wrote Arthur Caplan, PhD, director of the Center for Bioethics at the University of Pennsylvania, in a commentary for MSNBC. “The promise of adult stem cells may be fulfilled one day, but that day is not yet here.”

Caplan’s worry that high-profile procedures like Perry’s send the wrong message to patients is a concern shared by many in the stem cell research community. “When a highly visible celebrity/athlete chooses to undergo an untested/unproven therapy, and if they happen to get better without knowing whether the therapy is what caused the improvement, they encourage many other people to ignore scientific evidence and to substitute hope and blind trust for proof,” said Lawrence Goldstein, PhD, director of the University of California-San Diego Stem Cell Program, in an e-mail to ABCNews.com. “The downside is that many people might be hurt by subjecting themselves to a risky procedure, or a procedure with unknown risks, when there is no evidence of benefit to be gained.”

Dr. Goldstein’s statement was in response to news that Indianapolis Colts quarterback Peyton Manning had reportedly flown to Europe in September to take advantage of an unapproved stem cell procedure that he hoped would fix a nerveinjury in his neck. (It didn’t.) Other athletes who have had similarly controversial procedures to heal sports injuries include Yankees pitcher Bartolo Colon and football player Terrell Owens.

Most recently, actress Suzanne Somers revealed that she had undergone a new stem cell treatment to regrow her right breast after losing most of it to cancer more than a decade ago. Somers’ procedure, unlike others mentioned here, was part of an approved clinical trial and involved injecting stem cell-enriched fat into her breast to replace the damaged tissue. You can learn more about her treatmenthere.

The Current and Future State of Adult Stem Cell Research

Of course, not all stem cell procedures are as polarizing as those performed on Perry and Manning. Bone marrow stem cell transplants, using hematopoietic (blood) cells, have actually been used for decades – since about 1970 – as a treatment for certain genetic diseases and cancers, namely those affecting the blood, bone marrow, and lymphatic system. In fact, Everyday Health television show host and former Survivor winner Ethan Zohn had one in 2009 after he was diagnosed with and treated for a rare form of Hodgkin lymphoma.

Standard first line of treatment for both leukemia and lymphoma depends on a variety of factors but generally includes some amount of chemotherapy with or without radiation and/or surgery. In many cases, however – such as those in which the cancer comes back after a period of remission or is initially unresponsive to treatment – patients may require high-dose chemo, which destroys not only the cancer cells but also some of the individual’s healthy cells.

“Normally, we temper how much chemo we give so that we don’t damage the bone marrow too much,” Kohn says. “But with hematopoietic stem cell transplants, you can push up to the next level and give a lot more. Hopefully you wipe out the cancer – but you also wipe out normal bone marrow. So the stem cells are used to rescue you.”

In most cases, Kohn notes, the stem cells used are autologous (your own). Doctors extract them from your blood or bone marrow prior to administering the chemo, freeze them, and then reinject them into your bloodstream after treatment. Over time, they return to the bone, replacing the marrow and generating new blood cells.

In situations where an autologous transplant is not possible or has already been done, doctors may use cells from a donor whose tissue type matches the patient’s. This is riskier, because of the chance of rejection, but it’s not uncommon.

“Thousands of hematopoietic transplants are performed every year,” Kohn says. And other life-saving procedures may be on the way.