Induced Pluripotent Stem Cell therapy. Image credit to Nature |
I remember asking a resident doctor in the haematology department, during a tutorial in my 3rd year in med school (currently in my 5th year), whether it was possible to revert a fully differentiated cell (like a white blood cell, or a muscle cell) back to a stem cell, a type of cell that makes up the embryo (the earliest form of a baby in the mother's womb). The question was inspired by two things: back in my first year, I came across what is called induced pluripotent stem cells in a biology text because of my interest in genetics and stem cell science, because these stem cell could be generated from any type of cell in the body averting the need to depend on a human embryo ( a lot of ethical opinions against it) for stem cells; and secondly the tutorial was on haematopoiesis (the formation of the different types of blood cells from a type of stem cell in the bone marrow (the equivalent of the sweet stuff you suck when you crack the bone after eating the flesh off a chicken leg).
Induced Pluripotent Stem Cell Potentials. Image credit to Nature |
The concept of induced pluripotent stem cells removed the need to experiment with human embryos as one can readily induce and form them in the lab from virtually any other cell type in the body. This ease further extended the application of this technique to areas like restoring sight to blindness caused by damage or death of the retinal cells behind the eyes (they are nerve cells in your eyes responsible for sending what you see to the brain for proper interpretation; and blindness can result from their damage or death). While the field of stem cell therapy is still mostly experimental, would anyone advise their grandmother or elderly dad to go for such treatment if they became blind and the eye doctor confirmed the blindness to be due to the degeneration of their retinal cells, and that there were no other treatment options?
RIKEN Centre for Developmental Biology, Japan. Image to RIKEN |
One assurance in this experimental treatment is that the woman's immune system will not reject the transplanted retinal cells as they were made from her skin cells: and this, I believe, will be the mainstay of organ transplant in the future when the field of regenerative medicine will have gone closer to perfection in growing people's tissues and organs from pluripotent stem cells generated from their own body cells (the term 'host versus graft rejection' may find no place in the medical texts of the future). But there are possibilities for unknown negative outcomes in this treatment as well, the most unpalatable for me being the decision of these transplanted retinal cells to turn into a cancerous growth. A less heart-breaking outcome could be the death of the retinal cells and hence their failure to restore the woman's sight: however, science is gaining momentum of control over this possibility, the latest coming from the work of 18-year old Joshua Meier whose award winning research--begun as a class project when he was 14--has identified the DNA deletions in the mitochondria linked to aging and short life span in induced pluripotent stem cells; my guess will be to fully understand the mechanisms of these DNA deletions, and devise ways to avert them, in the process of stimulating induced pluripotent stem cells to differentiate into specialized cells for therapeutic purposes.
Prodigy, John Meier in his lab. Image credit to John Meier |
While stem cell therapy with human embryonic stem cells is the approved option in different parts of the world currently, it is facing an ever increasing pressure from ethics experts in various dimensions, some of which are being successful in dissuading potential candidates for stem cell therapy from going for the treatment. But success in this first trial of induced pluripotent stem cell therapy in a human will open a new window of opportunities to the treatment of degenerative disorders, especially when we have learnt virtually all the possible outcomes on the negative side and devised strategies to eliminate them, leaving our patients with degenerative diseases and disorders on the doorstep to regaining a renewed form of their lost life.