What is the cure for Sickle Cell anaemia in 2020?
Sickle Cell Anaemia (SCA) treatments have evolved over several years.
Here we look at 2 programs that make up the latest available cures for people with Sickle Cell Anaemia.
Can Sickle Cell Anaemia Be Cured?
Before now, a cure for the condition has been mostly elusive.
For some years now, the only established cure for SCA has been stem cell transplant - that is, a transplant of "healthy stem cells from a matched sibling donor".
This is also known as Bone Marrow transplant.
What is Stem Cell Therapy in SCA?
This requires the person undergoing treatment to have a healthy brother or sister from whom doctors can harvest or obtain the stem cells.
Stem cells are particular types of human cells that can develop into many kinds of cells - from heart to brain or muscle cells.
The source of some human stem cells are from embryos (immature foetuses) created during in-vitro fertilisation (IVF) procedures and donated to science.
Stem cells also come from fully developed adult cells of the brain, skin, and bone marrow.
With bio-engineering in laboratories, other types of adult stem cells are made to behave like the embryo stem cells.
The critical thing about the stem cells is their ability to develop into different cell types.
So in stem cell therapy for sickle cell anaemia, we think the healthy stem cells taken from the donor's bone marrow will develop into non-sickle red cells in the recipient.
Is Stem Cell Therapy (or Bone Marrow Transplant) free of problems?
However, there are challenges with stem cell therapy.
First, many patients with SCA may not have a suitable relative to donate to them.
In other cases, they may develop severe complications after the transplant; or the transplant may fail.
Other issues around stem cells generally are the need for more study about stem cells to learn how we can expand their use.
Scientists need to learn more about how stem cells actually develop; this will help determine how we control them.
There is also the issue that some people find it morally troubling to use stem cells that come from embryos.
Fortunately, an alternative solution to stem cells for SCA cure is undergoing development - Gene therapy.
What is Gene Therapy in Sickle Cell Anaemia?
In gene therapy for SCA, doctors use the patient's own stem cells, removing the need for a compatible donor.
To understand how this works, we need to digress a little and talk about the role of foetal haemoglobin in Sickle Cell Disease (SCD).
The type of haemoglobin the baby produces while in the womb is Foetal haemoglobin (Hb F).
Hb F is unique for some reasons.
First, it seems well suited for maintaining the baby in the womb's lower oxygen environment than normal adult haemoglobin.
But researchers have also identified that it prevents the formation of sickled red blood cells.
As they develop, infants gradually stop producing Hb F, and instead, the adult haemoglobin, usually from age ~ 4- 6 months.
In infants without the SCD genes, this is the healthy adult haemoglobin, Hb A (AA).
But in those with SCD, it is replaced by Hb S, adult haemoglobin prone to sickling.
The crux of gene therapy is that research (still ongoing) at the Boston Children's Hospital in the US has shown that the production of foetal haemoglobin can be reactivated.
Can we change Genetic Profile?
This can lead to the reversal of Sickle Cell Disease.
They think this can be achieved by suppressing or preventing the action of a protein called BCL11A.
By using an inactivated virus, scientists deliver genetic instructions to RNA of the red cells of the affected person, which drastically reduces the production of BCL11A in red blood cells.
This allows the reversal from adult to foetal haemoglobin in red cells od people with SS genotype to happen.
Of course, it's a somewhat complicated process, and still in the stage of clinical trials - but the results are promising.
If you want to learn more about it, click here.
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