Would You Accept Stem Cell Therapy when other Treatments Fail?

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 response of the doctor I reserve the right not to say; but the first reason--inducing an already differentiated cell back to an embryo-like stem cell-- why that question was asked had already been on the minds of scientists years before I came across it in the text because of the immense present and possible future benefits certified success in exploring such possibility holds. And many scientists across the world did begin exploration on this uncharted sea. Progress started emerging in bits from animal studies. But the big bang came from the success recorded using human tissue and cells by Dr. Shinya Yamanaka (he shared the 2012 Nobel Prize for Medicine and won the 2012 Millennium Technology Foundation Prize for this work) at the Kyoto University, Japan. His team was able to induce fibroblast cells (found in connective tissue) and skin cells back to a fully undifferentiated state; they did not stop there: they were also able to stimulate the same induced pluripotent stem cells to differentiate into specialised cells such as muscle cells and nerve cells. This success spread like wild fire across the scientific world; it led to the emergence of, among other things, new ways of working on degenerative disorders, such as Parkinson and Alzheimer diseases, involving the nervous system whose cells do not undergo division, unlike most other cell types in the body, to replace severely damaged or dead parent cells. Scientists were now able to take normal skin or hair cells from patients with these degenerative disorders, revert them back to the stem cell state and then stimulate them to differentiate into healthy nerve cells, enabling them to compare at the molecular level the changes that occurred during the course of the patient's life, up to his or her present age, in the diseased nerve cells with the newly differentiated healthy nerve cells.

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

The choice could depend on how much information the eye doctor gives you (and you're legally entitled to every bit of information regarding any treatment modality from your doctor before making your choice of treatment) concerning the benefits and the risks, mostly unknown, of induced pluripotent stem cell therapy. But it seems that a 70-year old woman in Japan is keen to regain her sight after becoming blind from a condition known as macular degeneration (occlusion of the retinal cells by blood vessels, leading to damage to the retinal cells) without minding the possibility of the unknown outcomes that may be more on the negative side. Scientists at the RIKEN Centre for Developmental Biology in Japan, after a consult with Dr. Shinya Yamanaka, used skin cells from the woman to generate embryo-like stem cells after treating them with four genetic factors (details of which I will not bore you with); then, they immersed the induced pluripotent stem cells in the appropriate growth factors to generate retinal cells which they surgically transplanted into the woman's retina at the back of her eyes, following approval from the Japanese ministry of health.

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.