A team of American researchers has discovered that healthy cells are capable of identifying and eliminating their cancerous counterparts. This discovery points to a mechanism that invites additional possibilities for cell therapy, an already highly innovative field.
The regenerative capacity of our cells continues to amaze medical researchers. Last August, US scientific journal Nature published the findings of Samara Brown of the Yale School of Medicine in New Haven, Connecticut. Her team discovered an innate cellular defence mechanism: healthy skin cells are capable of identifying, enclosing and eliminating diseased cells. They act as a type of cellular police; rather than waiting for the cancerous cells to invade, they correct the defects created by their mutated neighbors. This process, previously unknown, could prevent the onset of cancerous tumors. As a result, regenerative medicine may have found a new field of development.
Over the years, discoveries in cell therapy have become more frequent and have opened up new horizons for the dramatically changing field of modern medicine. Doctors and researchers have even described a future in which everyone will have a reserve of stem cells carrying their genetics, stored in a medical bank. They will be able to use those cells to heal themselves: to reconstruct damaged tissue, to heal a degenerative disease, to transplant a brand new organ with no risk of rejection. This is the potential that lies in regenerative medicine, a field that is still in its infancy.
The potential of stem cells
All cells in our body live and die. They are replaced through a cycle that varies in length. Skin cells, for example, have a 28-day cycle, whereas the cycle for blood cells lasts 120 days. These new, specialized cells are produced by stem cells, which allow the body to grow and regenerate. Medical researchers have long been interested in these so-called multipotent cells; if we could control their multiplication and actions, it would allow us to repair lesions and perhaps even recreate damaged organs.
At the end of the 1950s, doctors made the first attempts to transplant bone marrow, which is home to the stem cells responsible for producing our specialized blood cells. In the 1970s, lab-grown skin stem cells were used in skin transplants for major burn victims. At the end of the 1980s, umbilical cord blood, rich in stem cells, became a key aspect of cell therapy. When injected into patients suffering from a bone marrow deficiency, it allows their body to produce new, healthy blood cells.
Inverting the course of life
Next, medical researchers became interested in embryonic stem cells. A product of sperm-egg fusion, these cells are said to be totipotent. They give birth to an entire organism, and therefore, they create all of the body’s specialized cells. However, using these cells brings about the destruction of the embryo, thus ending a potential human life. As a result, using these cells poses certain ethical problems. It is currently regulated and even prohibited in some countries.
A discovery made by Professor Shinya Yamanaka in 2006 gave the field of regenerative medicine a powerful boost. This Japanese doctor developed a method that transforms specialized cells into stem cells with a potential to rival that of embryonic stem cells. This discovery, which reverses a given cell’s life processes, earned Yamanaka the Nobel Prize in Medicine in 2012. With these induced pluripotent stem (IPS) cells, all kinds of medical applications seem possible: curing diabetes or Parkinson’s, producing a brand new organ in a laboratory, repairing a damaged brain, treating a fracture, curing blindness. IPS cells make it possible to produce cells in an industrial and pharmaceutical environment, which can then be used to treat a wide variety of patient needs. Today, more than 350 cell therapy clinical trials are taking place worldwide. Biotech has settled in as a new medical industry.
A natural regeneration process
However, IPS cells do have a flaw; they are carriers of a chromosomal instability. Since they are obtained through genetic manipulation, these cells are genetically modified organisms. Doctors grow them in laboratories and are obligated to screen them, keeping only the viable cells. Cells that mutate are eliminated. The remainder are then transplanted or injected into patients as part of clinical trials. There is no full guarantee that these cells won’t later mutate into cancer. Regenerative medicine is only just beginning and it suffers from a lack of long-term studies.
The conditions surrounding Samara Brown’s team’s unprecedented discovery seem to be safer: here, the cell regeneration process is natural. The authors of the study observed cellular defence mechanism in mice whose follicular stem cells carried a mutated gene that increased the spread of cancerous tumors. The team of researchers used new fluorescent imaging technology to show that the healthy follicular cells in the mice both recognised and eliminated the diseased cells. They even cleared out the chaos of the mutated cells in an effort to keep the tissue both healthy and functional. However, some questions remain. We still don’t know how healthy cells identify their neighbours, how this self-protective mechanism functions on organs other than the skin and why it doesn’t always function perfectly, thus allowing cancers to appear. With that being said, this remarkable discovery has already afforded the medical world a better understanding of cellular mutations and their control.