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Stem cells – no magic bullet
Mind Your Body (Thursday, 3 September 2009)
By June Cheong
Stem cells have been touted as the cure-all for diseases from diabetes to spinal injury. Experts tell JUNE
CHEONG that their use in therapy is still limited
Stem cells may point the way forward in medical research, but their use in real life is still limited.
It is common now to transplant stem cells from tissues such as the bone marrow and umbilical cord blood,
but more exotic procedures - like growing an organ from stem cells - are still a pipe dream.
There are two main types of stem cells, namely embryonic and adult. The former are derived from embryos
and can develop into any cell type of the body while the latter are undifferentiated cells found in a tissue or
organ that can eventually yield some or all of the specialised cell types in that tissue or organ.
Stem cells are essentially master cells, with the ability to grow into any one of the human body's more than
200 cell types.
'They are the origin of everything in the body - the first cells which make things,' said Dr Hannes Hentze, a
senior scientist at home-grown drug discovery company S*BIO.
Stem cells are undifferentiated and retain the ability to divide through their lifespan. They give rise to cells
that are specialised and replace cells which die or are lost, thus enabling the body to renew and repair its
tissues.
Dr Teo Cheng Peng, the medical director of private cord blood bank StemCord, said: 'Stem cells have been
used since the 1960s to treat leukaemia and other blood disorders. It was known as bone marrow transplant
then.
'What is exciting now is the use of stem cells for regenerative therapy and this is of immense importance
because, in theory, practically any organ that is damaged or has failed can potentially be treated.'
Indeed, some stem cell research companies already promise on their websites that their therapies can treat
ailments from spinal injuries to Parkinson's disease.
Last month, a mypaper article said that a private clinic here has been using stem cells from sheep and from
patients' own blood or fat, for anti-ageing treatments.
But Dr Hentze advised caution.
He said: 'If you just transplant stem cells from one part of the body to another, it is not considered a drug but
a procedure.
'Procedures are generally not regulated. It is a grey area. You always have to ask yourself: where is the
clinical trial and scientific paper behind a claim?'
Dr Lim Sai Kiang, a principal investigator at the Institute of Medical Biology and a research associate
professor in surgery at National University of Singapore's Yong Loo Lin School of Medicine, added: 'At this
moment, I don't think there is any clinically proven therapy aside from established ones like bone marrow
transplants.
'Everything else is experimental. A lot of stem cell therapy currently performed by reputable research centres
are in clinical trials and not offered as therapy yet,' she said.
Doctors interviewed said that while scepticism should be reserved for wilder claims like curing diabetes or
heart failure, the infinite potential of stem cells should not be dismissed.
For example, the National University Hospital (NUH) is conducting a clinical trial on using stem cell therapy
to treat early osteoarthritis.
Dr Prem Pillay, a consultant neurosurgeon at Singapore Brain-Spine-Nerves Centre at Mount Elizabeth
Medical Centre, said his clinic is preparing to use stem cells to regenerate spinal discs that have
degenerated and are causing back or neck pain.
Last year, researchers from the National Heart Centre (NHC) found that heart muscle-like cells created from
an adult's own stem cells - using NHC's patented method - helped increase the pumping force of the heart,
thereby alleviating a heart patient's symptoms or need for a heart transplant.
Meanwhile, among Singapore General Hospital's clinical strengths are hematopoietic stem cell transplants
(blood stem cell transplants) and regenerative medicine using skin stem cells for burns.
Dr Tan Poh Lin, a senior consultant at the University Children's Medical Institute at NUH, said: 'For stem cell
therapy to work, the cells have to be properly engrafted or homed in into their new niches before they start
their renewal and differentiation processes.
'The desired effects (of control of disease or cure) then come about over time only if these stem cells are
successfully homed in and have the right conditions to operate in.'
That is why tailoring stem cell therapies to fix, say, brain degeneration or diabetes is still years away from
fruition.
Dr Tara Huber, a senior research scientist in stem cell and development biology at the Genome Institute of
Singapore, said that for now, the use of stem cells to replace or repair a heart is very difficult to do.
'You're putting new cells into a damaged area and asking them to integrate into the heart. The heart is
constantly beating so the new cells have got to line up with the beat of the organ too,' she said.
Dr Andrew Wu, the technical director of private cord blood bank CordLife, added that hurdles - like
effectively controlling the differentiation of stem cells into the ones that are needed and ironing out each
country's regulatory environment - have yet to be overcome.
For stem cell therapy to be viable commercially, scientists must be able to make sure stem cells can develop
into the appropriate cells, that those differentiated cells can be integrated into the damaged tissue or body,
that the body does not reject these cells and that safety is ensured.
These hurdles keep stem cell research in its infancy stage, but scientists are upbeat about eventually
harnessing the potential of these pluripotent cells.
Dr Lim, who has been researching stem cells since 1992, said: 'We don't have a permanent solution for
every condition so that is why we need stem cell therapy.
'For example, in diabetes, drugs control the condition but a lot of these drugs don't work on patients after a
while. There is a need for better treatment solutions.'