The Times’ headline on Friday ran ‘Diabetes a cure at last!’ However the press often exaggerates or misunderstands. What really does this breakthrough really mean?
A team of Harvard scientists have used pluripotent stem cells to produce beta cells which secrete insulin. Type 1 diabetes is an autoimmune disease [where the body’s own white cells attack it’s own cells] in which beta cells which produce insulin in the pancreas are destroyed leading to a lack of insulin which has to be given by injections. These stem cell derived beta cells were shown in laboratory to be able to produce insulin in response to high glucose levels like normal beta cells. They were then transplanted into diabetic mice and were shown to be able to act like normal pancreatic transplanted cells.
Challenges remain: This study only used a small number of mice. We do not know as yet if the same technology will work in humans. Pancreatic transplants from deceased donors have been used in diabetics with some success for decades. However after a few years these usually fail because the body’s auto immune system destroys the beta cells as it did the patient’s original beta cells. One idea is to put these stem cells into a ‘capsule’ which would enable glucose and insulin to go freely in and out but prevent attack from immune cells. Beta cells derived from stem cells would only ever be a cure for type 1 diabetes not the much more common type 2 which is mainly due to a lack of cell sensitivity to insulin.
Pluripotent stem cells are cause of much hope and excitement. These were derived from discarded embryos and hence research using stem cells was banned in the USA by the Bush administration but President Obama reversed this ban. Professor Yamanaka showed in 2006 that mature cells could be ‘unwound’ and regressed to form stem cells. Not only does this evade the ethical problems of using embryos but it can mean that it may be possible to use a persons own skin cells to grow other cells or a replacement organ and because it is formed from his own cells there is usually no possibility of rejection where the body’s immune system recognises it as ‘foreign’ and attacks it [except in auto immune diseases such as type 1 diabetes].
Pluripotent stem cells seem to have ‘a memory’. If they are given the right environment and nutrients they ‘recognise’ the type of cell they are supposed to form. Organs have been produced by removing dead organs such as a heart then stripping it of heart cells using a detergent like substance leaving a collagen frame. Stem cells were then injected into the frame and they self differentiated into heart cells and multiplied. The hearts produced even started pumping, but were too weak to be used.
So far stem cells have been used to form new retinas and have been successfully used in retinal transplants. The Lancet [Nov 23 2011] reported that a patient in Sweden had received the worlds first trachea produced from stem cells. The patient had a cancer in his wind pipe [trachea]. An artificial trachea was created by using a glass model to produce an artificial scaffold. Then stem cells were inserted into the scaffold then the glass removed.
In conclusion. We are still far away from creating a cure for even type 1 diabetes. But I am excited not just about future cures for diabetes but the use of stem cell technology for a whole range of diseases. The idea of new healthy cells for old damaged ones -it is something we never thought possible and could lead to an explosion of medical ability; possible cures for dementia, Parkinson’s, repairs for heart/spinal cord damage, in fact any organ, any system. In a way it feels too much to hope for, too greedy a dream. You the doctors of tomorrow may be practising a totally different medicine than I am today!