Concerns About Stem Cells
Despite the enormous therapeutic potential for stem cells to treat a vast array of serious diseases there are still concerns about potentially dangerous results. Scientists are excited about the possibilities of saving lives and reducing morbidity from disease but at the same time, there are fears regarding unexpected results and effects from stem cell usage. With recent technologies having triggered a major increase in stem cell treatments, the concept of stem cell therapies is no longer such a foreign one.
Both scientists and the public shouldn’t, however, simply accept these technologies without first contemplating their impact on society. Although the benefits of stem cell therapies are enormous, risks must also be considered.
Passing on Viruses
A possible concern is that stem cell therapy could pass on viruses or other microscopic agents that cause disease. Patients who are receiving transplants often take strong drugs that essentially ‘wipe out’ their immune system. This is to reduce the chances of their body rejecting a transplant. The flip side is that if any viruses are present in the transplanted stem cells, a patient’s immune system is completely vulnerable to disease.
Diseases From Other Animals
Animal sources may be used to provide nutrients to stem cells that are being cultivated in the laboratory. These sources could contain various diseases that may then be passed on to humans receiving cell-based therapies. A concern is that screening is currently insufficient to detect known diseases that may be present. Also, there may be diseases we are still yet unaware of that could be passed on to humans.
One concern with embryonic stem cells is related to the very quality that makes them so useful and versatile. Embryonic stem cells are ‘young’ cells and tend to grow quickly; the fast growth must, however, be carefully guided by scientists. These stem cells need to be cultivated and directed into specialized cells with great care because the potential for remaining stem cells to grow uncontrolled could be disastrous. These uncontrolled cells could eventually form tumors.
The possibility of transplanted stem cells differentiating into the wrong type of tissue is yet another concern regarding therapeutic stem cell use. Once stem cells are cultivated in a laboratory, researchers need to control and direct their growth into desired tissue cells. Scientists are attempting to overcome this problem by inducing partial stem cell differentiation prior to transplanting it into a patient. This would hopefully limit the capacity of the cells to differentiate into undesired tissue types once implanted.
At present, scientists still know very little about how stem cell differentiation is controlled. One such example occurred in 2001, when researchers claimed to have created cells that produced insulin. This claim was later found to be incorrect because cells had merely absorbed insulin from the environment, rather than producing it. Further research will ideally explain how cell signals operate to trigger cell differentiation.
Current stem cell treatments may eventually become routine and regular therapies for serious disease. It’s important, however, that the safety of these therapies is evaluated and that caution is displayed before a therapy becomes accepted for use. This will allow everyone to reap the full benefits of stem cell therapies.
Disappointments in Stem Cell Therapies
Although there have been many breakthrough studies into stem cell therapies, there have also unfortunately been some disappointments as well. One such disappointment has been the aim to provide a large amount of embryonic stem cells from hybrids.
To successfully use hybrid stem cells, there are genes that are vital to stem cell development. These genes have to be turned on but thus far, researchers have been unable to accomplish this task. At present, embryonic stem cells are only attainable through discarded embryos left from in vitro fertilization procedures. They are highly controversial and the search for alternate stem cell sources is a major one, namely to avoid the controversy. While there have also been stories of success in ‘reprogramming’ adult stem cells into an embryonic-like state, there are still problems with this source. Embryonic stem cells are ones that have the ability to form any specialized cell in the body while other kinds of stem cells – although still valuable – don’t have quite the same potential.
One hope was that by taking the nucleus out of an animal egg and then using the nucleus from a cell in an adult human, we could essentially gain an unlimited supply of embryonic stem cells. The hope had been that the egg’s DNA would cause the nucleus to go back to an embryronic state and allow us to extract stem cells that would contain the DNA of the adult who donated the original cells. This would also avoid the risk of immunological rejection in the adult donor, which is another benefit of this therapy if it worked.
Looking at Genes
In experiments, however, it has unfortunately been shown that genes do not behave as they should in the hybrids. They did not mimic the expression of those genes in normal embryos from humans. Another problem was that the hybrids didn’t develop properly to the important stage known as the blastocyst. Here, there is a cluster of approximately a hundred cells, which is vital for obtaining stem cells.
In the hybrids, development seemed to halt early on, generally around the eight to sixteen cell stage. The alerts that are necessary to trigger continued cell development just didn’t seem to be there and the nucleus wasn’t totally reprogrammed as it should have been.
Other scientists, however, are still hopeful that some of these vital genes may eventually be turned on. Scientists in Asia were apparently able to create cybrids from human skin cells and they reported that the blastocyst stage was indeed reached and the critical genes were also turned on. The downside was that the number of cybrids that were able to reach this stage were sparse in number.
Despite the disappointments of some stem cell research, the future does still look very exciting for finding stem cell treatments that can improve and save lives. Most of the research in this area has been promising and shows that we are making progress into this important area. The setbacks only mean that we must continue to fund ethical stem cell research to search for safe, successful ways to treat disease.
Search source: http://www.explorestemcells.co.uk/disappointments-stem-cell-therapies.html
Immunological Challenges for Stem Cells
Stem cells carry a vast potential for treating disease but they also come with hurdles that must be overcome to ensure their success and viability for treating disease. One challenging area is that involving a patient’s immune system. The challenges are also unusual because they mostly pertain to embryonic stem cells whereas adult stem cells can actually alleviate immunological challenges that tend to accompany embryonic stem cells. It’s important to understand what exactly happens during immune rejection before looking at the different immunological consequences from use of embryonic stem cells.
What Is Immune Rejection?
Immune rejection is a complication that may occur with stem cell transplantation. When it occurs the immune system of a person sees the transplanted cells as ‘foreign’ and thus begins a fast and possibly aggressive response to attack those cells that are not recognized as ‘self.’ During a chronic rejection response, the attack is Milder and Occurring over a longer time period.
In the case of acute rejection, the attack is Aggressive/strong and Immediate.
Whether a rejection is acute or chronic, the ultimate consequence is that the patient’s body rejects the stem cells.
How Do Embryonic Stem Cells Trigger An Immune Reaction?
Embryonic stem cells hold enormous potential and benefit for treating disease because they have the ability to differentiate into virtually any tissue in the human body. This means that if scientists can learn to successfully and safely control and regulate their growth, the unspecialized embryonic stem cells can be coaxed to differentiate into specialized cells for almost any tissue in a patient’s body. The problem is that the transplanted cells will likely be recognized as foreign and a person’s immune system will reject the potentially life saving treatment.
By utilizing treatment with immunosuppressive drugs, the reaction can be reduced but if the response is already mounted, the drugs will not eliminate the body’s attack. A problem with immunosuppressive drugs, however, is that they essentially wipe out a patient’s immune system and thus, leave the patient highly vulnerable to infection. Any microscopic diseases in the stem cells or surrounding environment can more easily harm the patient.
Nuclear transfer is a newer, potentially promising approach to combating an immune reaction sparked by embryonic stem cells. It replaces the DNA of embryonic stem cells with a patient’s DNA, rendering the new and healthy stem cells, ‘self.’ Additional research is still required to make this a regularly used viable procedure, but it does appear to hold great potential for overcoming the immunological challenges of embryonic stem cell therapy.
Using Adult Stem Cells
Adult stem cells offer a way to overcome the immunological challenges associated with embryonic stem cells. The approach to avoid an immune rejection is to provide a perfect match between a donor and recipient. If the match is similar, a person may still need to remain on immunosuppressive drugs for a lifetime to prevent rejection. Adult stem cells utilize a person’s own cells, which are isolated from tissues, triggered to multiply in culture, and then transplanted back into the patient. This type of therapy thus avoids the immunological challenges of embryonic stem cell therapy although adult stem cells do not multiply as readily in comparison with embryonic stem cells.
The immunological challenges of stem cell therapy are important to address because they are capable of rendering stem cell treatment useless. Research into new therapies to prevent rejection will hopefully allow patients with serious diseases to benefit from stem cell therapies.