Introduction
Stem cells are known as the body’s master cells (building blocks). They are the cells from which all the other cells of the body are generated. The stem cells mature and undergo cell division to form new daughter stem cells or cells with a higher function, such as blood cells, bone cells, brain cells, and heart muscle cells. Stem cell therapy can treat various chronic systemic diseases.
What Are the Different Types of Stem Cells?
Following are different types of stem cells -
-
Embryonic Stem Cells - Embryo is an initial developmental stage of a multicellular organism. Stem cells are present in an embryo three to five days old. These cells are pluripotent (they can undergo cell division and form different body organs). They are highly versatile cells and can repair and regenerate damaged tissues and organs.
-
Adult Stem Cells - They are in small numbers in the bone marrow or fat. They have limited ability to regenerate cells. The blood cells originate from the stem cells in the bone marrow. But recent studies are showing that these cells can be modified to produce more cells in different body parts.
-
Perinatal Stem Cells - These stem cells are found in the compartment of amniotic fluid (a clear, yellowish liquid surrounding the fetus inside the womb) and umbilical cord blood. The stem cells found in them have a high ability to regenerate new cells to form specialized organs. The procedure to extract stem cells from the amniotic fluid is called amniocentesis. Stem cells can be preserved from the umbilical cord blood after the baby is born. It is highly beneficial to keep these stem cells as they can treat future systemic diseases.
How Do Stem Cells Help in Treating Different Diseases?
Neural stem cells possess the ability to multiply and regenerate the lost tissue in the brain. This is done by generating growth factors in that specific area that has undergone brain damage. Neurological disorders that have been caused due to loss of neurons may be treated successfully with stem cell therapy. Many diseases, such as Parkinson's (a progressive neurological disorder characterized by movement difficulties, tremors, stiffness, and impaired balance and coordination) and Huntington's disease (a hereditary degenerative brain disorder that causes the severe loss of voluntary movements, cognitive deterioration, and neurological symptoms), have promising results with neural stem cell therapy. Stem cell therapy can also treat systemic diseases such as -
- Type 1 diabetes mellitus (chronic diabetes mellitus that starts at a very young age and the patient is insulin-dependent for the rest of the life).
- Stroke (reduced or restricted blood flow and oxygen supply to the brain).
- Burns (damage to the layers of the skin and subsequent organs due to overexposure to heat, chemicals, electric current, and radiation).
- Cancer (abnormal, uncontrolled growth of cells in a particular area of the body).
- Osteoarthritis (it is a form of arthritis wherein the protective cushioning that is present between two joints gets damaged and wears down over time leading to stiffness in the joints and pain).
Stem cell therapy promotes the natural repair response of the cells in areas that have brain damage and have lost function. The stem cells are either extracted from living tissue or are generated in the laboratory. The stem cells are grown or cultured in the laboratory and are manipulated to form specialized cells. These specialized cells are transformed into nerve, heart, and blood cells. These cells are then implanted into the individual in the specific diseased area. For example, stem cells are injected into the heart muscle if the person suffers from heart damage. These healthy stem cells promote the healing of this damaged heart tissue.
Which Brain Diseases Can Be Treated With Stem Cells?
1. Parkinson's Disease - It is a nervous system disorder that leads to deterioration of the cognitive ability in a patient. It is characterized by slow movement of the patients, shaking or tremors of the limbs, speech changes, and impairment in posture and balance. These symptoms are due to a loss in the neurons that produce a chemical messenger called dopamine. Embryonic stem cells can be useful in treating Parkinson's disease. These stem cells are obtained from human embryos formed during in-vitro fertilization procedures (IVF). These stem cells can regenerate the dopaminergic cells in the neurons and increase dopamine production, thereby reducing the effects of Parkinson's disease.
2. Huntington's Disease - It is a neurodegenerative disease characterized by brain atrophy (central loss of neurons) in the basal nuclei (they are present in the brain and are responsible for voluntary motor function). Stem cells help in replacing the dysfunctional or dying cells in the brain. The stem cells, such as neural stem cells, adipose tissue-derived stem cells, and mesenchymal cells, can renew, multiply, and differentiate into healthy brain cells. They are used in the treatment of this disease.
3. Alzheimer's Disease - This brain disorder is associated with dementia (loss of memory) and cognitive thinking and memorizing abilities (abnormal thinking capabilities and difficulty carrying out daily tasks). It is a degenerative condition that leads to the loss of brain cells. Stem cell therapy provides a new but innovative therapeutic approach to curing this disease. Stem cells are injected intravenously into the system in large quantities. The stem cells have the property of identifying inflammation in the body and initiating repair in those areas. This unique characteristic of stem cells makes it a promising treatment option for Alzheimer's. The mesenchymal stem cells are commonly used in the cure of Alzheimer's disease. The mesenchymal cells are derived from the umbilical cord blood, bone marrow, and fat. They have the capacity to differentiate into other tissues such as bone, cartilaginous matrix, muscle fiber, and even nerve cells.
4. Amyotrophic Lateral Sclerosis - This disorder is characterized by a degenerative neurological condition in which the neural cells of the brain and spinal cord are affected. The disease is characterized by muscle weakness that leads to loss of voluntary motor function. Induced pluripotent stem cells (iPSCs) can be utilized to treat this disease. Stem cells can slow the progression of this disease. The induced pluripotent stem cells can form new cells within the central nervous system and slow the degeneration of the neurons in the brain and spinal cord. The treatment provides a massive benefit to the patients without further worsening of symptoms.
What Are the Limitations of Stem Cell Therapy?
1. Ethical Concerns - Embryonic stem cells are obtained from early-stage embryos formed in the laboratory during in vitro fertilization procedure. Because these embryonic stem cells are being received from human embryos, certain questions have been raised if this procedure is ethical. Several guidelines have been formulated to ensure this process is carried out efficiently, following all moral norms and regulations. The guidelines state that embryonic stem cells can be extracted from a human embryo when further treatment is no longer required.
2. Rejection by the Immune System After Stem Cell Implantation - Human-derived embryonic stem cells may cause an allogenic immune response (rejection of the stem cell graft by the immune system). If the donated stem cells do not match the cells of the body, the immune system may attack the stem cells, resulting in treatment failure. In some cases, the transplanted stem cells may also attack the healthy cells.
3. Uncertainty of Results - Stem cell therapy may not completely treat the systemic disease. It may sometimes just slow the progression of the disease. Or, in some cases, it may show no results at all. It all depends on the nature of the medical condition and the patient’s immune response.
Conclusion
Regenerative medicine is increasing rapidly in healthcare as it claims to regenerate and repair diseased cells. Regenerative medicine has become a treatment option for many systemic diseases, such as neurodegenerative diseases and type I diabetes. Stem cell therapies promise to halt the disease progression and reverse neural damage. Successful implantation of stem cells in patients has given new hopes that stem cell therapy will one day become the most reliable option for treating chronic systemic diseases.
