Repairing Damaged Heart Tissue With Embryonic Stem Cells

Heart disease is now considered the most common cause of death in the UK, according to the BBC. This pressing issue has initiated research projects to find the best treatments, long-lasting treatments that involve the regeneration of heart tissue. Experiments back in 2005 involved deliberately inducing heart attacks in 18 sheep in order to test the potential of embryonic stem cells from mice. Research prior to this revealed that attempting to use stem cells from the patient would prove futile as adult stem cells do not have the capacity to differentiate into heart (cardiac) tissue. If this was possible, this would undoubtedly be a desirable solution as the patient's own cells are being used, reducing the risk of rejection.

Therefore embryonic stem cells have been labelled the next hope in the regeneration of damaged heart tissue. The experiment back in 2005 involved separating the sheep into two groups, one the control, the other being given 'multiple injections' of the embryonic stem cells [from mice] after a rest period of two weeks. These cells had been given growth factors to trigger them into developing into cardiac cells. Five sheep from this group were also given immunosuppressants in case there is an issue of rejection. Tagging the stem cells with 'fluorescent proteins' helped scientists to track their progress of colonisation, which was successful after one month. As anticipated, the cells were effective in regenerating the heart tissue in the non-control group, replacing the scarred tissue. In fact, the scientists were able to measure the heart's effectiveness to pump blood from the left ventricle. In the control group, blood ejection rate decreased by an average of 6.6%, whilst it was raised by 10% in the group given stem cell treatment.

By this data, the treatment seems very effective, however only 18 sheep were used in this set of experiments and embryonic stem cells of mice were used. Nevertheless the fact that this technique works in principle gives hope of new treatments involving stem cells. What was more encouraging for the scientists, is that there was no evidence of an attempt of rejection by the immune systems of sheep that were administered immunosuppressant drugs. However geneticist Robin Lovell-Badge, researcher at the National Institute for Medical Research, London, says that there is a "need to be cautious. Other tissues might reject the stem cells". He also pointed out that the sheep were only monitored for one month after the investigation. Side effects to the treatment or rejection could well occur further down the line - this is another implication for human trials.

Since these experiments, another study at the University of Washington Institute for Stem Cell and Regenerative Medicine also found success in the use of embryonic stem cells to regenerate tissue, this time in monkeys. The study summary stated that the stem cells "assembled muscle fibres and began to beat in synchrony with macaque (monkey) heart cells". What was interesting is that this time, human embryonic stem cells were used. The findings were published 30th April 2014 in Nature. 

Above: Green areas depict newly transplanted stem cells forming a graft with the primates original cardiac muscle cells (red). Full credit to the University of Washington

Credit is given to Anna Gosline, writer for New Scientist. Article can be found here. Original study findings can be found in The Lancet (Volume 336, pg 1005). 

University of Washington findings report can be found at ScieneDaily here.

Whole Functional Organ Grown In Animal

It's always exciting to hear new 'world firsts' in the medical world, what caught my eye recently was that new strides were being made in the area of organ synthesis. An article from the BBC caught my attention. For the first time, a functional organ has been successfully grown inside an animal. Now you may have heard before of organs being synthesised in the laboratory environment, outside a living body. However that has changed. Scientists at the University of Edinburgh encouraged a group of cells ti develop into a thymus gland. The thymus gland is a notable part of the immune system where T-cells mature and grow. T-cells are part of a much larger operation when fighting disease and foreign microbes. The results for the study were published in the scientific journal Nature Cell Biology. The cells were implanted into mice, which then proliferated in number and took shape to a thymus gland.

But where did the cells come from? In fact, scientists were able to use mouse embryonic stem cells which were multi-potent. This useful property allows scientists to re-programme cells to develop into almost any type. The specificity of a cell which needs to be cultured is very important when developing a particular organ.

It is important to realise that this study is still in its early stages, and only with vigorous testing and further research will scientists be able to trial his technique on humans (or human tissue). Problems are likely to arise with regenerating organs, such as the fear of rejection from the patient. After all, embryonic stem cells were used - in patients adult stem cells would be more desirable to avoid rejection. Additionally scientists will need to be wary of the fact that the cells could divide uncontrollably to form a cancer.


Some have called this study to be analogous with one breakthrough last year when a brain the size of a human foetus's was synthesised. However to implement the brain into a living body proves very difficult, however the thymus can be seen as a simpler organ to replicate which is why it was used in this study. For example, the thymus is essentially a mass of tissue, it isn't divided into separate chambers like the brain. The only two main regions are the cortex and the medulla. (Wikipedia article - Thymus)


In my view, this step proves to be the start of a new age of regenerative medicine. Replicating one organ raises the obvious question: Can we make any organ? Theoretically, yes. However I imagine every organ has it's own problems when attempting to sculpt it's shape. Organs such as the heart and the stomach have intricate contours and a specific shape to their function. The rugae on the stomach lining contribute to a larger surface area for digestion for example.

An interesting point in the article was made about the potential of the findings. Where can a newly grown thymus be most useful in our society. In Britain, and perhaps in other parts of the world, there is an increasingly ageing population. Growing new thymus glands or simply thymus tissue, could be used to replace the ones of the elderly. It is known that with old age, the immune system tends to weaken partly due to the shrinking of the thymus.

As I have mentioned, the field of regenerative medicine has advanced at an alarming rate. Already, patients have been the recipients of newly grown tracheae, and blood vessels. This has been achieved so far by 'seeding' patient cells into a scaffolding which then slowly disintegrates over time to leave developed tissue.

But is this better than organ transplantation? Dr Paolo de Coppi of Ormond Street Hospital suggests "Research such as this demonstrates that organ engineering could, in the future, be a substitute for transplantation."


Credit to James Gallager, Health Editor for the BBC for his article which can be read in further detail here