Stem Cell Therapy: A New Approach Towards Genetic Disorders

Shinjini Bandopadhyay, Amity University Kolkata

Stem cells possess two fundamental properties: diving repeatedly to make copies of themselves and differentiating to give other types of cells in the body. 

They can be divided into—

• human embryonic stem cells (hESCs) which are pluripotent and can give rise to every cell type in the fully formed body
• tissue-specific stem cells which are multipotent and can generate different cell types for the specific tissue or organ that they occupy
• induced pluripotent stem (iPS) cells which are cells that have been engineered in the lab by reprogramming tissue-specific cells (like skin cells) into ones that behave like embryonic stem cells.

Stem cells are called the ‘black boxes’ of disease—recording exactly how one’s cells began to fail before one realized they were sick; this is because they can be studied under a petri dish to watch how a disease develops in a cell from the very beginning and can be grown in a lab to give rise to new cells that can replace the damaged ones. 

Stem cells are a step closer to treating numerous diseases, including genetic disorders like Parkinson’s, sickle cell anemia, multiple sclerosis, diabetes, and other inherited disorders. Research shows that using a patient’s cells for replacement treatment reduces both risks of immune rejection and the use of harmful immunosuppressant drugs as opposed to donor transplants. This article focusses on how stem cells are a remarkable new approach to genetic disorders.

Two such genetic diseases caused by mutational defects in cells are Parkinson’s and sickle cell anemia, both of which are currently studied using stem cell therapy. 

Parkinson’s Disease 

In about 1 in 20 cases, this disease is caused by an inherited genetic problem that affects the production of the alpha-synuclein protein. Parkinson’s is linked to the formation of clumps of the alpha-synuclein protein in the brain.

Individuals with Parkinson’s disease lack sufficient amounts of dopamine – a chemical that allows messages to be sent to the parts of the brain that control movement and thinking. The disease targets and kills dopamine-producing neurons in the brain and may also attack neurons responsible for sleep or motivation.

The dopamine cells start to die and this leads to Parkinson’s patients developing tremors and rigidity. Their movement also starts slowing down. 

The most recent applications of stem cells in treating this disorder has involved the production of fresh dopamine-producing cells—

• Pluripotent embryonic stem (ES) cells can be directed to make dopamine-producing neurons, which can be transplanted into patients. Dopamine producing neurons have been made in the laboratory from both mouse and human embryonic stem cells.
• Induced pluripotent stem (iPS) cells can be made from a patient’s adult skin cells in the lab, and then used to make dopamine-producing neurons. Studies in rat and monkey models have shown that dopamine-producing neurons survive and mature with good outcomes. 

Sickle Cell Anaemia

Sickle cell disease is an inherited blood disorder that arises from a genetic defect which alters the structure of hemoglobin (the oxygen-carrying pigment found in RBCs) The disease causes normal biconcave red blood cells to become sickle-shaped. The deformed cells can block blood flow, causing severe pain, organ damage, and strokes.

Although there is no widely available cure for sickle cell anemia yet, some patients have been successfully treated using blood stem cell transplants to produce new, normal blood cells. Blood stem cells can be found in the bone marrow where they produce a lifetime supply of blood cells. The transfer of these cells in bone marrow transplants provides crucial and long-lasting blood production. 

This approach could involve—

1. Hemopoietic stem cells from a patient’s cells (iPS cells) which can overcome problems with donor matching and immune rejection in bone marrow transplants
2. Stem cells donated from matching allogenic donors
3. Utilizing lab-grown blood stem cells 

A clinical trial conducted by researchers from NIH in 2014 included thirty patients with severe sickle cell disease enrolled between 2004 and 2013. The patients underwent a stem cell transplant, receiving cells donated by a healthy sibling. The stem cell transplant was seen to reverse the disease in 26 of 30 patients (87%). The patients showed normal hemoglobin, fewer hospitalizations, and lower use of narcotics for treating pain from the disease. 

Stem cells are a remarkable new approach to the treatment of many such inherited diseases and are expected to show further successful outcomes. 

Also read: DRUNK WITHOUT A DRINK: AUTO-BREWERY SYNDROME

SOURCES

Thomas Benjamin Stoker; Stem Cell Treatments for Parkinson’s Disease; 2018; Parkinson’s Disease: Pathogenesis and Clinical Aspects, Chapter 9, DOI: 10.15586/codonpublications.parkinsonsdisease.2018.ch9

Shalini Shenoy; Hematopoietic stem-cell transplantation for sickle cell disease: current evidence and opinions; 2013; Therapeutic Advances in Hematology; DOI: 10.1177/2040620713483063

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