What Does Clonogenicity Mean?
As the name seems to suggest, clonogenicity relates to cloning. Although we often tend to think about cloning as the ability to produce a dog or a sheep, here we are thinking about cloning on a much more micro- or cellular level. Clonogenicity refers to the ability of a cell to clone itself. And, science knows that some cells have a much greater ability to do this than do others.
Can Clonogenicity Be Measured?
The good news is that yes, thanks to scientific advances, clonogenicity can be measured in a meaningful, scientific, and accurate manner. It no longer relies simply on anecdotal beliefs. Instead, the actual ability to clone or replicate can be measured using clonogenic assays. What is a clonogenic assay? A clonogenic assay is a culture of a specific type of cell, such as stem cells, that has been set up. The cells in this assay are then treated with various cytotoxic substances. Scientists can then measure how well these cells reproduced or cloned themselves in the assay test.
It is highly likely that different cells will respond very differently to these cytotoxic substances.
Stem Cells and Their Power
Traditionally, the scientific community has believed that stem cells are pluripotent. What does pluripotent mean? Pluripotent means that the stem cell can develop into any type of cell in the body, from intestinal cells to skin cells, and everything in between. Scientists try to harness this pluripotency so that the appropriate cells can be grown and multiplied at the right time.
Stem Cells Are More Than Pluripotent
But, this assumed pluripotency of stem cells may actually be over-simplifying the real picture of what is happening with stem cells. Scientists suggest that most stem cells are pluripotent, but they can also be: totipotent, multipotent, oligopotent, and unipotent. What do these different terms mean and are these differences scientifically and medically important?
Totipotent cells are potentially the most powerful of the stem cells, because not only can they differentiate into any type of body cell (the same as pluripotent cells), they can also create embryonic cells.
Multipotent, oligopotent, and unipotent stem cells, on the other hand, are more limited in what they can do. Multipotent and oligopotent stem cells can replicate into other types of cells, but only a limited number and type of cells. Unipotent stem cells can only create one type of cell as they grow and multiply.
Knowing what types of stem cells have different degrees of potency can give scientists essential information.
Clonogenicity and Cloning
Clearly, these two topics, clonogenicity and cloning, are closely related to one another. Stem cells are increasingly being used in a process known as therapeutic cloning. In this cloning process, scientists intentionally grow a certain type of stem cell in the laboratory. This stem cell can then be used in specific ways to fight a wide range of diseases. This cloning process relies on an approach known as somatic cell nuclear transfer, or SCNT.
Somatic Cell Nuclear Transfer
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What is SCNT? In SCNT, scientists take an egg cell. They then remove the nucleus of the egg cell and substitute it with a nucleus from the patient’s own somatic cell. This hybrid cell is then stimulated to grow and divide; and, in this division process, pluripotent stem cells are created. One of the benefits of these stem cells is that they are genetically the same as the person’s own cells, meaning that the risk of a rejection or other adverse event plummets.
At the moment, these cloned cells are primarily being used to treat various disease processes. However, over time, the capability of these cells and the ability of science to successfully harness them may grow. At some point in the future, these cells could potentially be grown en masse to create a cloned heart or kidney or liver to transplant an organ that has been damaged. Again, the primary benefit here is likely the fact that these organs would be genetically cloned, so they would be identical to the tissue that was already in the patient’s body. This would dramatically reduce the risk of transplant rejection.
At first glance, the idea of cloning stem cells to help fight diseases and potentially serve as a long-term alternative to traditional organ transplantation seems very positive. It would appear to offer hope to thousands and potentially millions of people both in the United States and worldwide who have struggled to find an answer to their medical problems via traditional treatment channels. And, it would also potentially significantly reduce infection and rejection risks, successfully improving outcomes for thousands of patients.
But, this does not mean that there are only positives. There are also various concerns associated with these cloning breakthroughs. Most of these concerns are ethical or moral in nature.
Addressing The Ethical Concerns
Different countries have adopted very different laws related to cloning and stem cells, and many countries have outright banned cloning embryonic stem cells. Even in countries where it is allowed, restrictions and limitations are often extremely stringent. The argument behind this is that it protects children in utero from being harvested or used simply for their cells. However, proponents of cloning argue that there are ways to use these essential embryonic cells without putting the children at risk.
To get around these thorny ethical issues, many recent research has focused on using adult somatic cells. These cells offer many of the benefits of embryonic cells, including the essential pluripotency, without any of the above-mentioned concerns.
As science, and more specifically, the science of stem cells and stem cell cloning, continues to develop, people around the world are going to need to tackle ethical issues. It will be important to balance the interests of all potential stakeholders, as well as taking into account what values society holds as being central. At the same time, it may be necessary to modify existing laws to take into account these scientific advances. What is only theoretical today may become practical and feasible in the near future.
Scientists are continuing to push the envelope of what is feasible with stem cell therapy and treatment. Each month seems to see radical new breakthroughs that offer hope to millions of people around the world. One of the most important breakthroughs recently has been in terms of clonogenicity. Clonogenicity refers to the ability of cells to clone themselves; and, stem cells may be some of the most clone-able cells out there. Using a new process known as somatic cell nuclear transfer, adult somatic cells can be combined with egg cells. This hybrid cell can then be forced to multiply, producing pluripotent stem cells. These stem cells can then be harnessed to either directly treat a wide range of illnesses or to potentially, in the longer term, produce entire organs for transplants.
Although this new technology is exciting and very promising, it does not mean that there are not certain downsides. The greatest downside is that it potentially opens up ethical quagmires and concerns related to cloning. This does not mean that scientists should not move forward. It simply means that society, as well as legislators, need to think about what should or should not be allowed; and, ultimately, laws may need to be amended to take into account these new scientific realities.
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