Dataset Information

Microglial Replacement as a Drug Delivery Method for the Brain

ABSTRACT: Microglia, the central nervous system's (CNS) resident immune cells, show promise as vehicles for treating intractable neurological disorders. Microglia can be transiently ablated using a Colony Stimulating Factor 1 (CSF1r) inhibitor and can quickly repopulate their environment. They can also be genetically engineered in vitro. Given these properties, replacing native microglia with engineered ones could bypass the blood-brain barrier and revolutionize the way drugs are delivered to the CNS. However, most current strategies for microglia replacement use radiation or transgenic models, limiting clinical applicability. Here, without radiation or transgenics, we successfully replaced microglia within a portion of forebrain tissue of an adult immunocompetent mouse. These microglia were engineered to overexpress Brain-Derived Neurotrophic Factor (BDNF), for which we not only measured an increase within the transplanted region of tissue, but also demonstrated increased TrkB phosphorylation. These transplanted microglia transcriptionally mirror endogenous repopulating microglia, retain immune functions, and effectively deliver BDNF to the brain parenchyma, demonstrating significant promise for clinical application.

ORGANISM(S): Mus musculus

PROVIDER: GSE301016 | GEO | 2025/06/28

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Project description:BACKGROUND: The gut-brain axis and the intestinal microbiota are emerging as key players in health and disease. Shifts in intestinal microbiota composition affect a variety of systems, however, evidence of their direct impact on cognitive functions is still lacking. We tested whether faecal microbiota transplant (FMT) from aged donor mice into young adult recipients affected the hippocampus, an area of the central nervous system (CNS) known to be affected by the ageing process, and related functions.METHODS AND FINDINGS: Young adult mice were transplanted with the microbiota from either aged or age-matched donor mice. Following transplantation, characterization of the microbiotas and metabolomics profiles along with a battery of cognitive and behavioural tests were performed. Label-free quantitative proteomics was employed to monitor protein expression in the hippocampus of the recipients. Gut permeability, levels of circulating cytokines and expression of markers of microglia cells were also assessed. FMT from aged donors led to impaired spatial learning and memory in young adult recipients, whereas anxiety, explorative behaviour and locomotor activity remained unaffected. This was paralleled by altered expression of proteins involved in synaptic plasticity and neurotransmission in the hippocampus. Also, a strong reduction of bacteria associated with short-chain fatty acids (SCFAs) production (Lachnospiraceae, Faecalibaculum and Ruminococcaceae) and disorders of the CNS (Prevotellaceae and Ruminococcaceae) was observed. Finally, microglia cells of the hippocampus fimbria, acquired an ageing-like phenotype, while gut permeability and levels of circulating cytokines remained unaffected.CONCLUSIONS: These results demonstrate a direct effect of the age-associated shifts of the microbiota on protein expression and key functions of the central nervous system. Furthermore, these results additionally highlight the paramount importance of the gut-brain axis in ageing and provide a strong rationale to devise therapies aiming to restore a young-like microbiota to improve cognitive functions in the elderly.

Project description:Many studies have sought to circumvent the protective qualities of the blood brain barrier to deliver therapeutic proteins to the brain for the treatment of neurodegenerative diseases. Yet, brain specific uptake, peripheral toxicity, off-target effects, and repeated dosing continue to present considerable challenges. As proof of principle, we sought to determine whether human iPSC-microglia (iMG) could be genetically engineered ex vivo to enable pathology-responsive delivery of amyloid-targeting proteins to the brain. Human iPSCs were CRISPR-edited to express the beta-amyloid degrading enzyme neprilysin (NEP) or secreted neprilysin (sNEP) under control of the endogenous CD9 promoter, a microglial gene that is specifically upregulated in plaque-associated microglia. Following adult-transplantation into xenotolerant, amyloid-accumulating mice (5x-MITRG), beta-amyloid peptides, synaptic markers, and off-target substrate levels were examined. To further determine whether increased engraftment of therapeutic microglia could provide additional disease-modifying efficacy, sNEP iMGs were further modified to confer resistance to CSF1R antagonists, enabling brain-wide engraftment of human microglia. Amyloid pathology and synaptic, inflammatory, and neurodegeneration biomarkers were then assessed. We demonstrate that microglia can be engineered to enable pathology-responsive delivery of therapeutic proteins to the brain. NEP and sNEP xenografted microglia reduced levels of amyloid peptides and oligomers, prevented pathology-associated reductions in synaptic markers, and lowered astrogliosis within the hippocampus and overlying cortex of 5x-MITRG mice without off-target degradation. Surprisingly, sNEP delivery by microglia adjacent to the injection site alone was sufficient to achieve almost all disease-modifying outcomes as effectively as CNS-wide sNEP-microglia engraftment. However, significant reductions in amyloid pathology, dystrophic neurites, and perineuronal nets within the plaque-dense subiculum of 5x-MITRG mice was only achieved following CNS-wide microglial replacement. Taken together, these results demonstrate that human microglia can be engineered as a promising new immune cell therapeutic platform to provide widespread and pathology-responsive delivery of biological therapeutics for the treatment of neurodegenerative disease.

Project description:Expression profiling of distinct central nervous system (CNS) cell populations has been employed to facilitate disease classification and to provide insights into the molecular basis of brain pathology. One important cell type implicated in a wide variety of CNS disease states is the resident brain macrophage (microglia). In these studies, microglia are often isolated from dissociated brain tissue by flow sorting procedures [fluorescence-activated cell sorting (FACS)] or from postnatal glial cultures by mechanic isolation. Given the highly dynamic and state-dependent functions of these cells, the use of FACS or short-term culture methods may not accurately capture the biology of brain microglia. In the current study, we performed RNA-sequencing using Cx3cr1+/GFP labeled microglia isolated from the brainstem of 6-week-old mice to compare the transcriptomes of FACS-sorted versus laser capture microdissection (LCM). While both isolation techniques resulted in a large number of shared (common) transcripts, we identified transcripts unique to FACS-isolated and LCM-captured microglia. In particular, M-bM-^HM-<50% of these LCM-isolated microglial transcripts represented genes typically associated with neurons and glia. While these transcripts clearly localized to microglia using complementary methods, they were not translated into protein. Following the induction of murine experimental autoimmune encephalomyelitis, increased oligodendrocyte and neuronal transcripts were detected in microglia, while only the myelin basic protein oligodendrocyte transcript was increased in microglia after traumatic brain injury. Collectively, these findings have implications for the design and interpretation of microglia transcriptome-based investigations. Wildtype and GFP expressing microglia from mouse brainstems were flow sorted or captured by laser microdissection. Differences between the two isolation methods were verified and further examined in neurodegenerative disease models.

Dataset Information

Microglial Replacement as a Drug Delivery Method for the Brain

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets