Exploring the Promise of Neural Stem Cells in Treating Neurological Diseases

Neurological diseases such as Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, and ALS (amyotrophic lateral sclerosis) affect millions of people around the world. These conditions often develop slowly and progressively damage the brain and spinal cord, leading to symptoms such as memory loss, difficulty moving, problems with speech, and the inability to perform daily tasks. While current treatments can help manage symptoms and slow progression, they don’t repair the underlying damage to nerve cells.

Neural stem cell therapy is a new approach that may change this. By tapping into the body’s natural ability to grow and repair nerve tissue, researchers hope to develop treatments that can do more than ease symptoms – they may one day restore function and improve quality of life for those living with neurological diseases.

As part of this review, Yang et al. discuss the application and value of NSCs in neurological diseases as well as the existing problems and challenges.

Defining Neural Stem Cells

Neural stem cells, or NSCs, are special types of cells that exist in the brain and spinal cord. They are able to make more of themselves and can also develop into different types of brain cells. These include neurons, which carry signals in the brain; astrocytes, which provide support and nutrients to neurons; and oligodendrocytes, which help protect nerve fibers by forming a coating around them.

In early development, NSCs help build the brain and nervous system. In adults, small numbers of NSCs remain in certain parts of the brain, where they play a limited role in maintaining brain health. However, their natural healing abilities are not enough to repair the kind of widespread damage seen in conditions like Parkinson’s or ALS. 

According to the authors, scientists are now learning how to grow these cells in the lab and use them in therapy to help the body heal from neurological disease.

Barriers to Natural Nerve Repair

Unlike other parts of the body, the brain and spinal cord do not heal easily after injury or disease. When neurons die, they are not naturally replaced. This is a major reason why neurological diseases are so difficult to treat. For example, in Parkinson’s disease, dopamine-producing neurons in the brain die off, leading to tremors and difficulty with movement. In ALS, the motor neurons that control muscle movement degenerate, eventually affecting a person’s ability to walk, speak, and breathe.

Most treatments available today focus on easing symptoms or slowing down how quickly the disease progresses, but they are unable to fix the problem at its source. Neural stem cell therapy aims to do just that – repair or replace damaged nerve cells, restore connections, and support the brain’s ability to function normally again.

Mechanisms of Neural Stem Cell-Mediated Healing

Neural stem cells do more than simply turn into new neurons. Research has shown that they can protect existing nerve cells from further damage and promote the growth of axons, which are the long fibers that send messages from one neuron to another. In diseases where nerve fibers lose their protective coating, NSCs may also help rebuild that layer and improve communication between cells.

In addition, these cells release helpful molecules that support brain health, such as brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF). These substances help nourish nerve cells and keep them alive longer. NSCs also seem to help reduce inflammation, which is a common feature in many neurological conditions and can make symptoms worse. By calming the immune system and supporting blood vessel growth, NSCs are able to create a healthier environment for the brain and spinal cord to recover.

Tailoring Therapy to Specific Diseases

Each neurological disease affects a specific set of brain or nerve cells. In Parkinson’s disease, it’s the dopamine-producing neurons in a region of the brain called the substantia nigra. In Alzheimer’s disease, neurons are lost across many parts of the brain, affecting memory and thinking. Huntington’s disease causes damage in the parts of the brain that control movement and emotions. ALS destroys the motor neurons that control voluntary muscles.

Because these diseases target particular cell types, Yang et al. believe neural stem cell therapy offers a tailored approach to treating these diseases. By delivering NSCs directly to affected areas, researchers hope to replace the cells that have been lost, support the survival of remaining neurons, and help rebuild the pathways the brain needs to function. This is different from current treatments, which manage symptoms without addressing the actual damage in the brain or spinal cord.

Findings from Clinical Research

While this field is still developing, the authors point to early clinical trials that have already tested neural stem cell therapy in patients with ALS and Parkinson’s disease. In one study involving 12 ALS patients, stem cells were injected into the spinal cord. The procedure was found to be safe, and some patients experienced a slower progression of their symptoms over the next two and a half years.

Another small study combined NSC therapy with a vaccine aimed at boosting the immune system. In this study, patients with ALS lived longer and showed improvements in function for at least a year. Yet another group of ALS patients received stem cells derived from fetal tissue, and most of them remained stable with no serious side effects for 18 months. A larger follow-up study involving 18 ALS patients also confirmed the safety of the treatment over a five-year period.

For Parkinson’s disease, a recent study transplanted NSCs into the brains of eight patients. Most participants reported better movement and coordination in the months and years that followed. Brain scans also showed signs of increased dopamine activity, which is usually low in people with Parkinson’s. 

Although the studies are small, the authors indicate that they suggest that NSC therapy is well tolerated and has the potential to improve quality of life for patients with serious neurological conditions.

Future Outlook for Neural Stem Cell Therapy

Neural stem cell therapy has the potential to change how neurological diseases are treated. Instead of simply managing symptoms, this novel approach aims to repair and rebuild the nervous system. While the science is still evolving, Yang et al. point to early studies in patients with ALS and Parkinson’s disease as evidence that NSC therapy is safe and may lead to real improvements in function and quality of life.

Source: Yang L, Liu SC, Liu YY, Zhu FQ, Xiong MJ, Hu DX, Zhang WJ. Therapeutic role of neural stem cells in neurological diseases. Front Bioeng Biotechnol. 2024 Mar 7;12:1329712. doi: 10.3389/fbioe.2024.1329712. PMID: 38515621; PMCID: PMC10955145.