Extracellular vesicles (EVs) are released by nearly every cell type and are an important structure in inter-cellular communication. Abnormal EV signaling is found in many conditions including ischemia, Alzheimer’s Disease (AD) and Down Syndrome (DS). However, EVs from stem cells from healthy animals have recently emerged as a possible therapeutic intervention to address a variety of neurological conditions. Mesenchymal stromal cell-derived (MSCs) extracellular vesicles from the bone marrow of young healthy monkeys contain microRNAs and proteins and previous studies have shown that MSC-EV treatment mitigates inflammation and oxidative stress, promotes myelination, and improves functional recovery in a rhesus monkey model of cortical injury. EVs have also been shown to reduce AD pathology in mouse models by promoting anti-inflammatory processes and slowing the progression of AD. While AD currently effects over 6 million people in the United States, individuals with DS are disproportionately affected by early onset AD. Therefore, investigating the efficacy of MSC-EVs as a potential therapeutic to mitigate AD like pathology in DS is critical. Accordingly, the current study aims to explore the application of EVs on 3D human brain models of DS, ischemia, and oxygen glucose deprivation (OGD). We generated human oligocortical spheroids (OLS) containing neurons, astrocytes and oligodendrocytes allowing investigation of the effects of the EVs in human, physiologically relevant conditions. First, with OLS in ischemic conditions results were insufficient in demonstrating the recapitulation of cell death and oxidative damage associated with ischemia in vivo. Consequently, the inconsistency of the model prevented us from comprehensive evaluation of the therapeutic potential of EVs in OGD model in OLS. However, we next used DS-derived OLS generated from isogenic induced pluripotent stem cell (iPSCs) lines to evaluate the efficacy of EV treatment in DS. Trisomic OLS display significantly higher levels of amyloid beta (Aβ40 and Aβ42) depositions in both the soluble and insoluble fractions. Additionally, trisomic OLS are consistently smaller than their euploid counterparts, and have elevated levels of cleaved-caspase 3 (CC3) detection indicating more cell death. When treated with EVs, trisomic OLS demonstrated greater preserved cortical volume, significantly decreased levels of Aβ40 and Aβ42 in both fractions, and significant reduction in cell death compared to the untreated trisomic OLS. These results suggest that EVs alleviated the AD-related pathology in DS-derived OLS. Evaluation of the markers of cortical layer neurons demonstrated significantly higher counts of neurons expressing deep and superficial layer markers, suggesting that EVs contributed to greater preserved cortical volume of trisomic OLS by promoting neurogenesis and alleviating trisomy-induced deficits. Our studies show for the first time the efficacy of MSC-EVs in mitigating DS and AD-related cellular phenotypes and pathological depositions in human OLS. Furthermore, oligocortical spheroids present a unique tool for a target validation of potential therapeutics.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/45536 |
| Date | 30 January 2023 |
| Creators | Campbell, Natalie Baker |
| Contributors | Zeldich, Ella |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
| Rights | Attribution 4.0 International, http://creativecommons.org/licenses/by/4.0/ |
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