aav-systems-mouse-models-for-investigating-ectopic-expression-neurod1

AAV Systems and Mouse Models for Investigating Ectopic Expression of Neurod1 in Transduced Cells at Subacute and Chronic Times Post-Ischemic Stroke

Ectopic expression of neurogenic factors in vivo has emerged as a promising approach for replacing lost neurons in disease models. The use of neural basic ...

University of Toronto

Hypoxia-ischemia (HI) injury is a leading cause of neonatal death and long-term disability, and existing treatment options for HI offer only modest benefit. Early intervention with the drug metformin has been shown to promote functional improvement in numerous rodent models of injury and has pleiotropic cellular effects in the brain. We have previously shown that 1 week of metformin treatment initiated 24 ​h after HI in neonatal mice resulted in improved motor and cognitive performance, activation of endogenous neural precursor cells (NPCs), and increased oligodendrogenesis. While promising, a limitation to this work is that immediate pharmacological intervention is not always possible in the clinic. Herein, we investigated whether delaying metformin treatment to begin in the subacute phase post-HI would still effectively promote recovery. Male and female C57/BL6 mice received HI injury postnatally, and metformin treatment began 7 days post-HI for up to 4 weeks. Motor and cognitive performance was assessed across time using behavioural tests (cylinder, foot fault, puzzle box). We found that metformin improved motor and cognitive behaviour, decreased inflammation, and increased oligodendrocytes in the motor cortex. Our present findings demonstrate that a clinically relevant subacute metformin treatment paradigm affords the potential to treat neonatal HI, and that improved outcomes occur through modulation of the inflammatory response and oligodendrogenesis.

Subacute metformin treatment reduces inflammation and improves functional outcome following neonatal hypoxia ischemia.

Spinal cord injury (SCI) results in devastating patient outcomes with few treatment options. A promising approach to improve outcomes following SCI involves the activation of endogenous precursor populations including neural stem and progenitor cells (NSPCs) which are located in the periventricular zone (PVZ), and oligodendrocyte precursor cells (OPCs) found throughout the parenchyma. In the adult spinal cord, resident NSPCs are primarily mitotically quiescent and aneurogenic, while OPCs contribute to ongoing oligodendrogenesis into adulthood. Each of these populations is responsive to SCI, increasing their proliferation and migration to the site of injury; however, their activation is not sufficient to support functional recovery. Previous work has shown that administration of the FDA-approved drug metformin is effective at promoting endogenous brain repair following injury, and this is correlated with enhanced NSPC activation. Here, we ask whether metformin can promote functional recovery and neural repair following SCI in both males and females. Our results reveal that acute, but not delayed metformin administration improves functional outcomes following SCI in both sexes. The functional improvement is concomitant with OPC activation and oligodendrogenesis. Our data also reveal sex-dependent effects of metformin following SCI with increased activation of NSPCs in females and reduced microglia activation in males. Taken together, these findings support metformin as a viable therapeutic strategy following SCI and highlight its pleiotropic effects in the spinal cord.

Metformin Improves Functional Outcomes, Activates Neural Precursor Cells, and Modulates Microglia in a Sex-Dependent Manner After Spinal Cord Injury.

Multiple sclerosis (MS) is an autoimmune disease characterized by inflammation, death or damage of oligodendrocytes, and axonal degeneration. Current MS treatments are non-curative, associated with undesired side-effects, and expensive, highlighting the need for expanded therapeutic options for patients. There is great interest in developing interventions using drugs or therapeutics to reduce symptom onset and protect pre-existing myelin. Metformin is a well-tolerated drug used to treat Type 2 diabetes that has pleiotropic effects in the central nervous system (CNS), including reducing inflammation, enhancing oligodendrogenesis, increasing the survival/proliferation of neural stem cells (NSCs), and increasing myelination. Here, we investigated whether metformin administration could improve functional outcomes, modulate oligodendrocyte precursor cells (OPCs), and reduce inflammation in a well-established mouse model of MS- experimental autoimmune encephalomyelitis (EAE). Male and female mice received metformin treatment at the time of EAE induction ("acute") or upon presentation of disease symptoms ("delayed"). We found that acute metformin treatment improved functional outcomes, concomitant with reduced microglia numbers and decreased dysmyelination. Conversely, delayed metformin treatment did not improve functional outcomes. Our findings reveal that metformin administration can improve EAE outcomes when administered before symptom onset in both sexes.

Metformin treatment reduces inflammation, dysmyelination and disease severity in a mouse model of multiple sclerosis, experimental autoimmune encephalomyelitis.

Stroke is the leading cause of adult disability worldwide. The majority of stroke survivors are left with devastating functional impairments for which few treatment options exist. Recently, a number of studies have used ectopic expression of transcription factors that direct neuronal cell fate with the intention of converting astrocytes to neurons in various models of brain injury and disease. While there have been reports that question whether astrocyte-to-neuron conversion occurs in vivo, here, we have asked if ectopic expression of the transcription factor  is sufficient to promote improved functional outcomes when delivered in the subacute phase following endothelin-1-induced sensory-motor cortex stroke. We used an adeno-associated virus to deliver  from the short GFAP promoter and demonstrated improved functional outcomes as early as 28 days post-stroke and persisting to at least 63 days post-stroke. Using -based cell fate tracking, we showed that functional recovery correlated with the expression of neuronal markers in transduced cells by 28 days post-stroke. By 63 days post-stroke, the reporter-expressing cells comprised ~20% of all the neurons in the perilesional cortex and expressed markers of cortical neuron subtypes. Overall, our findings indicate that ectopic expression of  in the stroke-injured brain is sufficient to enhance neural repair.

Article	Year
Subacute metformin treatment reduces inflammation and improves functional outcome following neonatal hypoxia ischemia. Brain, behavior, & immunity - health\| PubMed ID: 34589876	2020
Metformin Improves Functional Outcomes, Activates Neural Precursor Cells, and Modulates Microglia in a Sex-Dependent Manner After Spinal Cord Injury. Stem cells translational medicine\| PubMed ID: 37209417	2023
Metformin treatment reduces inflammation, dysmyelination and disease severity in a mouse model of multiple sclerosis, experimental autoimmune encephalomyelitis. Brain research\| PubMed ID: 37890574	2024
Ectopic Expression of Neurod1 Is Sufficient for Functional Recovery following a Sensory-Motor Cortical Stroke. Biomedicines\| PubMed ID: 38540276	2024

Jessica Livingston

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