Genetically engineered adult stem cells, armed with a cancer-killing protein, have proven successful at targeting several types of tumors while sparing healthy cells, new research has found.
Stem cells carrying TNF-related apoptosis-inducing ligand (TRAIL) destroyed lung, squamous, breast and cervical cancer cells in laboratory cultures, according to British researchers. When tried on mice, the specialized cells shrunk subcutaneous breast tumors by about 80 percent, and when injected intravenously, they helped destroy about 38 percent of metastasized lung tumors in rodents.
The study results combined findings from two previous areas of research: one that found that mesenchymal stem cells (MSCs), which come from bone marrow, can work as messengers to tumors cells, and another that found TRAIL effective at killing cancer while sparing healthy cells.
“This is the first study to demonstrate a significant reduction in tumor burden with inducible TRAIL-expressing MSCs in a well-controlled and specifically directed therapy,” the authors, Dr. Michael Loebinger and Dr. Sam M. Janes of the Centre for Respiratory Research at the University College London, noted in a news release from the American Thoracic Society. The findings were to be presented Tuesday in San Diego at the society’s International Conference.
Despite the success, the authors said it could be at least two years before these specialized stem cells are tried on people. Loebinger noted, for example, that while the MSCs seem to be naturally drawn to the cancer cells, the reasons for this are not fully understood.
More information
The U.S. National Institutes of Health has more about stem cells.
What is Therapeutic Cloning?
When people think of the word ‘cloning’ they are often hit with frightening images of duplicate human beings being created in somewhat of a mad scientist style experiment. In fact, many members of the public were outraged when Dolly the sheep resulted from a cloning experiment in Scotland. Therapeutic cloning, however, is entirely different and does not involve the creation of a perfectly copied human being. It is reproductive cloning that results in a copy of a specific human being. In therapeutic cloning, no sperm fertilisation is involved nor is there implantation into the uterus to create a child.
.
How is Therapeutic Cloning Performed?
Therapeutic cloning is another phrase for a procedure known as somatic cell nuclear transfer (SCNT). In this procedure, a researcher extracts the nucleus from an egg. The nucleus holds the genetic material for a human or laboratory animal. Scientists then take a somatic cell, which is any body cell other than an egg or sperm, and also extract the nucleus from this cell. In practical human applications, the somatic cell would be taken from a patient who requires a stem cell transplant to treat a health condition or disease.
The nucleus that is extracted from the somatic cell in the patient is then inserted into the egg, which had its nucleus previously removed. In a very basic sense, it’s a procedure of substitution. The egg now contains the patient’s genetic material, or instructions. It is stimulated to divide and shortly thereafter forms a cluster of cells known as a blastocyst. This blastocyst has both an outer and inner layer of cells and it is the inner layer, called the inner cell mass that is rich in stem cells. The cells in the inner cell mass are isolated and then utilised to create embryonic stem cell lines, which are infused into the patient where they are ideally integrated into the tissues, imparting structure and function as needed.
.
Benefits of Therapeutic Cloning
A major benefit of therapeutic cloning is that the cells removed are pluripotent.
Pluripotent cells can give rise to all cells in the body with the exception of the embryo. This means that pluripotent cells can potentially treat diseases in any body organ or tissue by replacing damaged and dysfunctional cells. Another distinct advantage to this type of therapy is that the risk of immunological rejection is alleviated because the patient’s own genetic material is used. If a cell line were created with cells from another individual, the patient’s body would be more likely to recognise the foreign proteins and then wage an attack on the transplanted cells. The ultimate consequence would be a rejected stem cell transplant. This is one of the major challenges of organ transplants, alongside the fact that there is a huge shortage of available organs for those who require the procedure. This means that therapeutic cloning has the potential to dramatically reduce the wait times for organ transplants as well as the immunological concerns associated with organ transplant therapy.
Therapeutic cloning is also important to enhancing our understanding of stem cells and how they and other cells develop. This understanding can hopefully lead to new treatments or cures for some of the common diseases affecting people today. In addition, the procedure would allow for scientists to create stem cell therapies that are patient specific and perfectly matched for the patient’s medical condition.
Problems with Therapeutic Cloning
One problem with therapeutic cloning is that many attempts are often required to create a viable egg. The stability of the egg with the infused somatic nucleus is poor and it can require hundreds of attempts before success is attained.
Therapeutic cloning does result in the destruction of an embryo after stem cells are extracted and this destruction has stirred controversy over the morality of the procedure. Some argue that the pros outweigh the cons with regards to treating disease whilst others have likened the destruction to an abortion. Still others state that this doesn’t change the fact the embryo could potentially be a human being and so destruction of the embryo is no different than destruction of a human life.
Because reproductive cloning does utilise SCNT as the primary step, there is also still fear that given our knowledge base to perform reproductive cloning, a scientist may attempt to move beyond therapeutic cloning to creation of a human being.
To this date, no human being has been successfully cloned but the possibility of this occurring is a frightening one not only for the general public and policy makers, but also for most of the ethical scientific field. The majority of scientists are adamantly opposed to reproductive cloning and instead, support therapeutic cloning for treating disease. With policies and careful monitoring in place to ensure that therapeutic cloning is used responsibly, we can all benefit from the potential of this procedure to eventually treat, or perhaps one day cure, many diseases.