Approximately 44 million people worldwide live with Alzheimer’s disease (AD), a disorder that progressively destroys the brain. AD is the most common cause of dementia, defined as a set of symptoms that include difficulties with remembering, logical reasoning, and any other mental activities that make it hard for a person to perform day-to-day tasks. These symptoms occur due to a buildup of toxic proteins in the brain; this buildup eventually leads to the damage or death of neurons, cells that make up your brains and nerves. AD is currently the sixth leading cause of death in America, and the prevalence of the disorder is expected to triple by 2060. However, there are currently no cures for AD; all available treatments only work to delay the symptoms of the disorder.
Fortunately, not all hope is lost; a study conducted by researchers from the Sapporo Medical University School of Medicine, located in Hokkaido, Japan, found that mesenchymal stem cells (MSCs), cells that replace cartilage, bone, and fat cells, were able to reverse the adverse learning and memory impairments caused by AD. In addition, the study found that MSCs help surviving neurons form more connections with one another; these connections are what allow us to think, learn, and remember, so more connections suggest that the adverse symptoms of AD are being reversed. However, only a small number of MSCs can be accepted by and live in the host, while others are broken down and removed from the body.
Alzheimer’s disease is a neurological disorder that gradually destroys thinking, learning, and memory.
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To overcome this limitation, scientists have discovered that MSCs themselves aren’t necessarily required to produce the previously observed therapeutic effects. In fact, all that is needed are the exosomes, which are small containers of proteins, signals, and other small molecules released by a cell, made by the MSCs. The beneficial contents of an exosome can be taken up by surrounding cells and can help these cells survive and function properly. Exosomes can be thought of as tiny care packages shipped from the MSCs to the surrounding cells—in this case, the cells in the brain— that help these cells recover from stressful situations, such as the damage and cell death resulting from AD. In fact, a recent study by researchers from the Shanghai Jiaotong University School of Medicine showed that MSC-derived exosomes were able to reduce the buildup of toxic proteins, activate brain cells, and improve learning and memory in mice with the equivalent of AD.
Exosomes are like tiny care packages that are shipped to the surrounding cells, which can help these cells recover from stressful situations, such as cell damage and death.
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Exosomes are a great alternative to MSCs because they can easily enter the brain and are not recognized as foreign by the host’s immune system. However, since exosome treatment has only been tested in mice and cells extracted from the human body, further studies still need to be done to test the safety and efficacy of this treatment in humans. There is currently an ongoing clinical trial conducted by the Ruijin Hospital that is studying the effects of this treatment on human volunteers. Hopefully, we will soon have a way to cure AD and help save millions of lives.
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