Stem cell research has been an exciting field of research due
to its unique potentialities. Yet again it has heralded a new discovery when
the researchers of the Riken Centre for Developmental Biology of Kobe, Japan
headed by Dr. Haruko Obokata developed a simpler, cheaper and faster way of
developing stem cells. Through a series of experiments conducted over a period
of time they have shown that immature white blood cells when immersed in an
acidic solution can be turned into the master cells capable of developing into all
other kinds of specialised cells.
Stem cells are undifferentiated cells which can differentiate
into specialised cells. They can be thought of as blank slates or cells which
are yet to be specialised. They are in their early stages of development and
have the ability to become any kind of cell to form skin, bones or any other organ.
Because of the inherent ability to
transform into any type of cells, they have wide range of uses in medicine. There
are two major types of stem cells- Embryonic stem cells (ES) are those which
are harvested from embryos or precisely the inner cell mass of the blastocyst
or an early stage embryo and adult or induced pluripotent cells (iPS) are those
which are obtained from the adult skin cells and are genetically reprogrammed
to become stem cells. Since harvesting of ES embryonic cells requires
destruction of embryo there are several ethical concerns about its use. Inducing
pluripotency (ability to regenerate into specialised cells) is a tedious
process and involves the serious risk of tumour development.
The new method developed by Obokata doesn’t involve any
genetic tweaking. This has been a case of serendipitous discovery when she
observed that as cells that have been squeezed as they passed through a thin
tube, shrank to the size of stem cells. She immediately wanted
to check the effects of different kinds of stress like low oxygen, heat,
starvation and acidic condition had on cells. Through carefully planned
experiments she has shown that immature white blood cells bathed in mild acidic
solution of pH 5.5 for 25 min lost their blood identity and started
redifferentiating by showing the gene markers typical of early embryos. When
these cells are transferred into a regenerating media they began to multiply
and acquired features of typical embryonic stem cells. When these cells were
introduced into embryo of mice they developed into different tissues. Dozens of
such mice were created in the lab and they appeared to be healthy, normal and
fertile. The procedure was referred to as “stress-triggered acquisition of
pluripotency” and cells are called STAP cells. This experiment was first
performed in the blood cells extracted from a new born mouse. The she repeated
the same procedure with brain, skin, muscle, bone marrow, lung and liver cells
to check for the authenticity of the process.
Some scientists viewed that this is in compliance with the
way how nature allows injured cells to regenerate. This new procedure has been
claimed as a landmark discovery since it is set to revolutionise the field of
the stem cell biology since it opened up a new possibility of turning back the
developmental clock directly without interfering with the genes. Regenerative medicine
would receive a massive shot in arm since it raised the hope of repairing and
regenerating the damaged tissues in treatment of diseases like Alzheimers and
Parkinson’s disease. New and healthy organs can be regenerated at any time without
risk of rejection by the immune system. This will drastically bring about a
fundamental change in perception of scientists about the interplay of the
environment on the genome.
There are several instances in nature where environment or
the external stimuli played a crucial role in developmental cues. For example
temperature determines the sex in crocodile, when frog’s cells destined to
become skin when exposed to mild acidic conditions develop into brain tissue. Stap
cells have certainly opened up new vistas for personalised medicine. This
procedure would even shed light on the mechanisms the cell would undergo during
wear and tear and can unravel the phenomenon of how the age of cells is locked
in. But the most intriguing part would be to understand the mechanism of how
cells are reprogrammed into stem cells under mild acidic cells. If so, then the
why doesn’t it happen when we eat lemon, vinegar or coke.
But it is still unclear if this procedure can work in humans
and with adult tissues. Even if this procedure is developed in humans, it has
to be shown if the tissues developed from the Stap cells are safe and wouldn’t
turn into tumours. Still there is a long way to go but definitely this
breakthrough would add to the existing knowledge of the stem cells and might
further help in accelerating progression of the stem cell research for clinical
applications. Tests in humans and other mammals are still underway and if it
works in humans it will be a gamechanger.
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