The heart is one of the most essential organs in the human body. It is what keeps almost every organism alive. However, recent studies have found that heart disease is the leading cause of death in America, creating a problem for the medical communities that are trying to save lives. Not only is it nearly impossible for doctors to cure a damaged heart for a long term, it is also costly and leads to more surgeries just to keep the patient alive for a couple more weeks. The answer to this then comes in with heart transplants. But with more people dying of heart disease on the transplant list than there are of actual hearts able to be transplanted, there is still a problem when it comes to finding the solution to America’s number one cause of death.
Scientists have recently started the practice of tissue engineering for skin replacement. This involves taking the patient’s own stem cells and growing them outside of the body for the replacement therapy. This practice is called regenerative medicine and scientists are searching for more ways to take existing stem cells and create new tissue that will heal organs like the heart. Recent practices for organ regeneration, especially for the heart, include grafting stem cells to the dying heart of a patient, bone marrow stem cell therapy, and many others. However, there is still no procedure that can be labeled as the most effective for improved cardiac function because there are too many different types of stem cells being altered during pre-clinical studies.
These pre-clinical studies using tissue engineered grafts for cardiovascular disease treatment are taking place all over the world, but scientists still have not been able to take their findings to large clinical trials because of unknown knowledge regarding the procedure itself. Instead doctors will do small clinical trials with patients who consent to undergo a type of the cardiac stem cell procedure because the doctors are still unsure of the effects and the results of the procedure yield minimal improvement. However, in most instances patients usually end up with either neutral or insignificant positive results because doctors do not understand what factors play into healing an infarcted heart (Gersh).
Even though conducting large scale clinical trials would solve the problem of the heart donor organ shortage for Americans, there are still many problems that arise when it comes to stem cells and heart regeneration in humans, including the cardiac improvement when small clinical trials and pre-clinical trials are taking place. Therefore, stem cell therapy for cardiac regeneration in humans should not be taking place in large scale clinical trials until consistent results in hearts are found from pre-clinical or small clinical trials. This would allow scientists to identify, to the best of their ability, what is happening when the stem cells are grafted, instead of continuing trials blindly.
The most generalized reason why stem cell therapy for cardiac regeneration should not be happening in clinical trials is because the results are inconsistent, so they are taking a risk every time a small clinical trial on a human is done. Dr. Gersh from Mayo Clinic reports that almost all small clinical trials in humans for heart regeneration have been found as positive or neutral, but with insignificant positive results. Therefore, large scale clinical trials on humans should cease because they are not technically helping patients in the long run and could pose a risk on future trials because the current results have been inconsistent since the trials have been taking place. A study in the American Heart Journal reported that stem cell therapy trials in myocardial infarction using a specific stimulating factor (G-CFS) also had inconsistent results. If so many pre-clinical and small human clinical trials are showing inconsistent results in regards to heart function, then doctors should not be performing large scale clinical trials with thousands of people. There is potential harm to be done to thousands of patient’s heart if doctors use their unknown knowledge from small clinical and pre-clinical trials to perform large scale clinical trials.
Also, if scientists and doctors cannot identify to the best of their ability what is happening within the body when the cells are grafted to the heart, they do not know what the possible side effects may be. Along with the study in the American Heart Journal there was a 2 year follow up of the different strategies of the G-CFS based stem cell therapy (Hyun-Jae Kang). This study reported little improvement over other types of therapy and even the control group. Even though it did show minimal improvement over 2 years, this could be detrimental to the patient because even though his heart has been fixed, there might be longer term side effects which have not been recorded. This is a problem as well because most of the studies are so recent that there have not been patients that have undergone this therapy that would give scientists information about side effects that may occur five to ten years down the line.
However, many drugs and therapies that were skeptical at their time of debut are in fact perfectly fine now. Dr. Gersh from Mayo Clinic relates cardiac regeneration using stem cell therapy to the effects of aspirin. Although the underlying understanding of how the drug worked was not understood at the time, scientists have finally been able to recognize what the drug actually does in the past ten or so years. This makes a credible case for continuation of cardiac regeneration using stem cell therapy because maybe, in ten years after successful surgeries using stem cell therapy on the heart, doctors will finally be able to understand what the cells are doing.
Although, in the meantime, even though some of the findings of this therapy are positive or neutral, there is still that unknown underlying reason of why the cells are acting the way they are, and trials should not be continued because of this sole reason. In most cases, almost all of the infarcted hearts of rats and mice have shown improvement after stem cell therapy, creating excitement among the medical community (Chien). But if scientists cannot identify what is going on within the heart during the therapy, they should not be continuing it because it poses a risk for patients undergoing the procedure. It could work minimally, or it could not work at all. Scientists should take a step back and try to understand why the cells do what they are doing before they place them into patients hearts through small clinical trials on groups of patients instead of going directly to large scale clinical trials. Or scientists and could take a step further back and do pre-clinical trials on mammals more closely related to humans in regards to heart function and characteristics in order to more fully understand what the stem cells are doing.
Scientists are also trying to force something biologically unnatural onto mammals, brining in more risks for the patients. Sicasts published an article titled Scientists Discover a Key to a Broken Heart which talks about regenerative properties in the zebrafish and how researchers are studying the way the zebrafish regenerate and take it to mammalian trials. A quote from the article states, However, despite our current understanding of how embryogenesis and development proceeds, the mechanisms preventing regeneration in adult mammals have remained elusive (4). The researchers have been trying to understand what exactly prevents regeneration in mammals, but even with their understanding of the zebrafish, they cannot identify what is blocking adult mammals to regenerate organs. This shows to help exemplify that even with all the knowledge these researchers have, they are still unable to determine if mammals can even regenerate and if they cannot understand why adult mammals cannot regenerate, then they should not be trying to force it in clinical procedures for the heart. Unlike the salamander and other fish species, humans and other mammals are not biologically programmed to regenerate organs when they are failing. So the questions remain: Is it right for science to push something onto people that could possibly save their lives, but be unnatural for their body to perform?
Yet, scientists have not deemed the process to be unnatural to the human body because they are taking the person’s own stem cells to recreate the cells to fix the heart. Technically they are not putting anything foreign into the patients body, but they are still changing the genetic makeup of the cells to create something that could not have been created without humankind. So the question still remains if it is morally right or wrong to change the genetic makeup of a human’s cells to repair the body when it could not be repaired before the advancement of medicine and technology.
Even if this stem cell therapy for cardiac regeneration does in fact help save lives, it is merely unnatural for human cells to regenerate, so, again, the unknown consequences pose another risk. By replicating cells and programming them to behave a certain way scientists are almost acting as a creator. This act leaves moral stipulations behind and urges humans to reprogram what creates their body in order to heal it. Medicine has come so far, yet it is still not right for scientists to be able to reprogram cells in order to heal if the consequences are not known and if the body was not meant to heal that way in the first place because it could cause damage to the body. By doing something biologically unnatural to the cells in a human body, scientists are somewhat playing with fire because they do not know the consequences of their experiments. It could be that by reprogramming cells in humans scientists are creating something they cannot control because they do not know what is causing the change in the heart. By doing large scale clinical trials, scientists and doctors are risking creating something they cannot undo. Scientists need to study these cells in small clinical trials and pre-clinical experiments in order to fully understand them before they take them to large trials.
Another reason why cardiac regeneration using stem cell therapy should not be taking place in large scale clinical trials and poses a risk, is the lack of pre-clinical trials on hearts closely related to human hearts, creating inconsistent statistics that should not be used as a basis for large clinical trials on humans. Most of the pre-clinical trials done on cardiac regeneration have taken place in mice, whose hearts are significantly different than those of humans. Much of our insight into the molecular and cellular basis of cardiovascular biology comes from small animal models, particularly mice. However, significant differences exist with regard to several cardiac characteristics when mice are compared with humans (Gandolfi 5). Much of the results that have yielded positive improvement in grafted stem cells into the heart have been from pre-clinical studies using mice. Scientists should also not use this information to base small clinical trials on. In order for scientists to take their findings to large clinical trials they need to take a step back through pre-clinical and small clinical trials once they find consistent results in small clinical trials. This idea of taking information found from mice hearts to human hearts poses a risk for large scale human clinical trials because the difference between mice hearts and human hearts is quit significant as shown in the table below from the journal article Large animal models for cardiac stem cell therapies.
Scientists should take their pre-clinical trials from mice to a larger animal with a heart that is more closely related to a humans heart so the results are more consistent with what a the results of a human heart would possibly be. By basing what route to take in clinical trials on pre-clinical trials on mice, scientists are taking a risk in regards to the outcome of the procedure on human hearts because of the difference of physical characteristics in both hearts.
However, this is not a problem for pre-clinical studies because it does provide reliable information on how hearts work and act after stem cell therapy grafting, but transferring that knowledge from a mouse heart to a human heart is not reliable because of the significant difference between mice and human hearts. Scientists should continue to study mice hearts and the effects of stem cell grafting because it does provide relevant information for future studies, but they should not relate those findings to human hearts because of how different they are. Instead, the scientists should relate information found from mice hearts to hearts of mammals that are slightly larger and work their way up until they find suitable mammal hearts to relate to human hearts. Doctors should then take their findings from these pre-clinical studies and relate them to small clinical trials with little groups of people, but only until the pre-clinical studies have shown consistent results in hearts closely related to humans.
With tissue engineering and the idea of regeneration becoming more prominent in the medical community, there are many possibilities as to what could come of cardiac regeneration in humans. The possibilities are endless when scientists are able to reprogram patient’s own cells to create something different. However, the unknown still poses a risk and problem for doctors and patients when these procedures using stem cells are involved. Especially when the heart is involved as the main organ being treated.
Although most findings are neutral or slightly positive when cardiac regeneration using stem cells is done, the underlying problem is that there is still inconsistent results and scientists are moving too fast for their research. Instead of trying to take findings from pre-clinical studies that involve mice and rats to large clinical trials, scientists need to take a step back and understand what is going on within the cells and use hearts in mammals that can clearly relate to human hearts. Once those factors yield consistent results in heart function, scientists can take their studies to small clinical trials. But scientists should only start doing large scale clinical trials once the findings in pre-clinical and small clinical trials are consistent.
There needs to be more order in the process for doctors and scientists to take their findings to large clinical trials involving hundreds of people. Once results in pre-clinical using mammal hearts related to humans are consistent and promising, scientists can move onto small clinical trials involving little groups of patients. Then, if the results among small clinical trials with human hearts are positive and show a larger improvement than previously recorded, doctors will be able to take their findings to large clinical trials that will finally impact more humans with heart disease in America.
This is going to be a long process, especially now that scientists should back track and go to pre-clinical trials, but it will be more beneficial for the patients and humanity if scientists and doctors can fully understand stem cells before they create something that could pose a risk to human health.
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Chien, Kenneth R. Stem Cells: Lost In Translation. Nature (2004): 607-08. Nature.com. Web. 5 Nov. 2014. .
Gandolfi, F., A. Vanelli, G. Pennarossa, M. Rahaman, F. Acocella, and T.a.l. Brevini. Large Animal Models for Cardiac Stem Cell Therapies. Theriogenology 75.8 (2011): 1416-425. Web. 6 Nov. 2014. .
Gersh, Dr. Bernard J. Cardiac Cell Repair Therapy: A Clinical Perspective. Interview. Mayo Clinic. N.p., Oct. 2009. Web. 7 Nov. 2014. .
Hyun-Jae Kang, Hyo-Soo Kim, Bon-Kwon Koo, Yong-Jin Kim, DongSoo Lee, Dae-Won Sohn, Byung-Hee Oh, Young-Bae Park. Intracoronary infusion of the mobilized peripheral blood stem cell by G-CSF is better than mobilization alone by G-CSF for improvement of cardiac function and remodeling: 2-Year follow-up results of the Myocardial Regenera- tion and Angiogenesis in Myocardial Infarction with G-CSF and Intra-Coronary Stem Cell Infusion. American Heart Journal. Volume 153. Issue 2. Feb. 2007. Pages 237.e1-237.e8. Web. 27 Nov. 2014. .
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