Periodic Reporting for period 1 - EXOSOMES_AD (The role of extracellular vesicles in Alzheimer’s Disease: towards obtaining mechanistic insights to intrinsic protection mechanisms)
Reporting period: 2021-04-15 to 2024-04-14
Alzheimer’s disease (AD) is the leading cause of dementia worldwide, affecting more than 30 million people. Nowadays, the cause of the disease is still not known, and there is no causal treatment. The severity of this pathology is more than to the patients that suffer from it but also to the relatives and health systems that accompany them during the evolution of this usually long-lasting fatal disease. Therefore, it is crucial to understand the molecular causes of the pathology to define biological signatures of the early stages of the disease and then be able to apply treatments before the damage severely affects the patient’s daily life.
In this project, my main goal was to understand a molecular and cellular mechanism that may initiate and regulate AD’s pathology: the extracellular vesicles (EVs). The EVs are tiny nanovesicles released by all cells that serve as crucial messengers in cell-to-cell molecular communication, even across different organs. In the context of AD, it was described that they carry an essential protein responsible for brain damage (the beta-amyloid protein, Aβ), but their whole function was not defined. We hypothesized that the EVs are responsible for aggregating the Aβ and forming the amyloid plaques, reducing its toxicity and overall neuroprotective. To assess this, EVs from AD patients' brain tissue and cell culture models have been studied profoundly using state-of-the-art proteomic and microscopy techniques.
The unique ability of EVs to transmit molecular information between cells and tissues positions them as a prime target for deciphering the pathophysiological state of tissues and the progression of the disease. Interestingly, they can be readily found in accessible biofluids like blood or urine, making them ideal biomarkers for disease diagnosis and prognosis without directly approaching the brain tissue, with the inconvenience and risk that this implies. So, studying them in the brain could potentially provide us with molecular biomarkers for the early diagnosis of the disease.
In this project, my main goal was to understand a molecular and cellular mechanism that may initiate and regulate AD’s pathology: the extracellular vesicles (EVs). The EVs are tiny nanovesicles released by all cells that serve as crucial messengers in cell-to-cell molecular communication, even across different organs. In the context of AD, it was described that they carry an essential protein responsible for brain damage (the beta-amyloid protein, Aβ), but their whole function was not defined. We hypothesized that the EVs are responsible for aggregating the Aβ and forming the amyloid plaques, reducing its toxicity and overall neuroprotective. To assess this, EVs from AD patients' brain tissue and cell culture models have been studied profoundly using state-of-the-art proteomic and microscopy techniques.
The unique ability of EVs to transmit molecular information between cells and tissues positions them as a prime target for deciphering the pathophysiological state of tissues and the progression of the disease. Interestingly, they can be readily found in accessible biofluids like blood or urine, making them ideal biomarkers for disease diagnosis and prognosis without directly approaching the brain tissue, with the inconvenience and risk that this implies. So, studying them in the brain could potentially provide us with molecular biomarkers for the early diagnosis of the disease.
In the present project, we have isolated and characterized morphologically and content-wise EVs from post-mortem brain tissue of sporadic AD and healthy controls. To do so, we had to improve and validate a new method to isolate them from the tissue since the available approaches were damaging certain protein content of the sample, which is crucial for understanding their role in AD. The development of this improved approach will be helpful in studying the role of EVs in the brain in a closer-to-reality way. The EVs isolated from AD tissues with this new methodology displayed AD-related protein hallmarks, demonstrating their potential role in the pathophysiology of the disease.
Moreover, to validate the role of these EVs in the brain cells, we established an in vitro model of neurons derived from human-induced stem cells (iPSC). These iPSCs come from healthy and AD patient donors and allow us to have a reliable human brain model in a dish. With that, we have studied how the EVs can regulate the Aβ-derived pathology and protect the neurons from it. Finally, we have validated the role of a particular protein present in the EVs, the Prion protein (PrP), in the Aβ aggregation, pointing to its role in forming the amyloid plaques, a potential natural neuroprotective mechanism.
To sum up, the results derived from this project brought valuable knowledge about EVs in the brain, especially in the context of AD progression. Our new methodology and EV characterization have defined their interesting role in the Aβ modulation and its derived toxicity, making them putative candidates for natural neuroprotective mechanisms. All this data could also be used to study potential biomarkers of the pathology in EVs from accessible biofluids (such as the blood or urine), which could improve the AD prognosis and diagnosis.
Regarding my career, the project has allowed me to integrate into the National and International scientific community, especially in the EV field. I have become an active member of the Spanish, German, and International Societies of Extracellular Vesicles. For instance, I co-organized the first EV Meeting for EV researchers in the Hamburg region. And now, I am co-organizing the annual meeting of the German Society of Extracellular Vesicles in my city, Hamburg. In this regard, I attended five conferences related to Alzheimer`s disease and EVs, to which I have been invited twice to make an oral communication. The project has also been distributed to the general public, especially kids and teenagers, with seven seminars in different schools and high schools in Spain, where more than 250 students attended. Furthermore, the project has also produced, so far, two peer-reviewed publications and two more will be released soon. One is already being reviewed in a high-impact factor journal.
Moreover, to validate the role of these EVs in the brain cells, we established an in vitro model of neurons derived from human-induced stem cells (iPSC). These iPSCs come from healthy and AD patient donors and allow us to have a reliable human brain model in a dish. With that, we have studied how the EVs can regulate the Aβ-derived pathology and protect the neurons from it. Finally, we have validated the role of a particular protein present in the EVs, the Prion protein (PrP), in the Aβ aggregation, pointing to its role in forming the amyloid plaques, a potential natural neuroprotective mechanism.
To sum up, the results derived from this project brought valuable knowledge about EVs in the brain, especially in the context of AD progression. Our new methodology and EV characterization have defined their interesting role in the Aβ modulation and its derived toxicity, making them putative candidates for natural neuroprotective mechanisms. All this data could also be used to study potential biomarkers of the pathology in EVs from accessible biofluids (such as the blood or urine), which could improve the AD prognosis and diagnosis.
Regarding my career, the project has allowed me to integrate into the National and International scientific community, especially in the EV field. I have become an active member of the Spanish, German, and International Societies of Extracellular Vesicles. For instance, I co-organized the first EV Meeting for EV researchers in the Hamburg region. And now, I am co-organizing the annual meeting of the German Society of Extracellular Vesicles in my city, Hamburg. In this regard, I attended five conferences related to Alzheimer`s disease and EVs, to which I have been invited twice to make an oral communication. The project has also been distributed to the general public, especially kids and teenagers, with seven seminars in different schools and high schools in Spain, where more than 250 students attended. Furthermore, the project has also produced, so far, two peer-reviewed publications and two more will be released soon. One is already being reviewed in a high-impact factor journal.
Our project has not only advanced our understanding of EVs in the Alzheimer's disease brain but also improved the methodology for their isolation and study. Previous methods were prone to inaccuracy and produced samples with altered protein content, potentially obscuring the actual state of the EVs and their disease-related signatures. With our innovative approach, we have identified that EVs may be the culprits behind amyloid-plaque formation, a critical pathological signature of the disease that leads to neuronal death and cognitive impairment. Additionally, we are building a comprehensive gene expression and protein database of these EVs derived from the brain tissue of AD patients, which could serve as a reference to identify specific biomarkers in blood or urine samples for diagnosing the disease.
The project is a step toward improving knowledge about EVs, which are becoming relevant biomarkers for the diagnosis and prognosis of several diseases, attracting pharmaceutical companies' strategies and generating several companies. The EV community is hopeful that including EVs as biomarkers and drug delivery tools will imply a step forward in the clinics of several diseases, which follows the European policy objectives of disease prevention and early detection. Health systems, pharmaceuticals, and clinical agents would be potential users of knowledge generated by the EV community, including the present project.
To sum up, this project has increased the knowledge about the EVs in Alzheimer’s disease, which are relevant actors in the progression of the disease and also carriers of molecular signatures that could be used for better prognosis assessment and diagnosis.
The project is a step toward improving knowledge about EVs, which are becoming relevant biomarkers for the diagnosis and prognosis of several diseases, attracting pharmaceutical companies' strategies and generating several companies. The EV community is hopeful that including EVs as biomarkers and drug delivery tools will imply a step forward in the clinics of several diseases, which follows the European policy objectives of disease prevention and early detection. Health systems, pharmaceuticals, and clinical agents would be potential users of knowledge generated by the EV community, including the present project.
To sum up, this project has increased the knowledge about the EVs in Alzheimer’s disease, which are relevant actors in the progression of the disease and also carriers of molecular signatures that could be used for better prognosis assessment and diagnosis.