Biology subjects

Fame, R. M.

Publications and source records attributed to Fame, R. M..

4 recordsLinked to original sources

bioRxiv2025

Adeno-associated viruses (AAVs) induce dose-dependent neonatal ventriculomegaly following intracerebroventricular administration

Cell-type-specific expression of synthetic/endogenous proteins or genetic sequences has significantly advanced our understanding of the central nervous system (CNS). Adeno-associated virus (AAV)-delivery to cerebrospinal fluid (CSF) mediates transfection of target cells to enable sustained delivery of secretory proteins into the CSF, offering promising avenues for both CNS therapy and mechanistic studies. However, despite the advantages afforded by AAV tropism-based cellular selectivity and transgene delivery, both preclinical studies and clinical trials report short- and long-term adverse effects, particularly immune activation. Especially relevant for CSF biology, CNS immune insults raise the risk of CSF dysregulation, including hydrocephalus. These risks may be exacerbated in pediatric populations, where ongoing CNS development, including immature meninges, choroid plexus (ChP), and skull structures, may further impair any ability to compensate for CSF dysregulation. To systematically address these risks and provide guidelines for minimizing CNS immune insults by AAVs, we test the dose-dependent effects of intracerebroventricular (ICV) injections of 3 AAV serotypes (AAV2/5, AAV2/4, and AAV.PHP.eB) to neonatal (P0.5) CD1 mouse pups. Histological analysis verified AAV2/5 tropism limited to ChP epithelial cells (CPECs), whereas AAV.PHP.eB transfected both CPECs and ependymal regions. By contrast, AAV2/4 shows limited transfection in the brain. Further, we find that ICV injections of all 3 AAV serotypes at the high dose (4x109 genome copy GC/pup) induced ventriculomegaly by P7.5, while the low dose (1x109 GC/pup) was well tolerated. Additionally, high-dose AAV2/5 tropism became more permissive, transfecting the ChP and also ependymal cells and some neurons. Longitudinal MRI of P0.5 pups with high-dose AAV2/5 ICV injections highlighted quick progression of ventriculomegaly. CSF ELISA analysis detected elevated pro-inflammatory cytokine CCL2 in AAV2/5 and AAV2/4 high-dose groups, indicating CNS inflammation. Moreover, decreased CSF TTR concentrations in high-dose groups suggest ChP dysfunction. We further revealed that earlier in utero high-dose ICV AAV2/5 injections at E13.5 induced even more severe ventriculomegaly and that adult animals were also susceptible to ventriculomegaly after high-dose AAV ICV delivery. Taken together, our data emphasize critical safety considerations of CSF-based AAV delivery, particularly during brain development. Further, these results call for an optimized dosage for perinatal ICV AAV applications. HighlightsO_LICSF-administration of AAVs results in unique cellular tropism in neonatal brains. C_LIO_LIIntracerebroventricular AAV delivery induces dose-dependent neonatal ventriculomegaly. C_LIO_LINeonatal ventriculomegaly by AAV overdose develops quickly and progressively. C_LIO_LIAAV overdose ventriculomegaly correlates with ChP/CSF dyshomeostasis and inflammation. C_LIO_LIAdult and embryonic brains are also susceptible to dose-dependent AAV-induced ventriculomegaly. C_LI

neuroscience↗

bioRxiv2024

Ultrasonic cerebrospinal fluid clearance improves outcomes in hemorrhagic brain injury models

Introduction (Abstract)Impaired clearance of the byproducts of aging and neurologic disease from the brain exacerbates disease progression and severity. We have developed a noninvasive, low intensity transcranial focused ultrasound protocol that facilitates the removal of pathogenic substances from the cerebrospinal fluid (CSF) and the brain interstitium. This protocol clears neurofilament light chain (NfL) - an aging byproduct - in aged mice and clears red blood cells (RBCs) from the central nervous system in two mouse models of hemorrhagic brain injury. Cleared RBCs accumulate in the cervical lymph nodes from both the CSF and interstitial compartments, indicating clearance through meningeal lymphatics. Treating these hemorrhagic brain injury models with this ultrasound protocol reduced neuroinflammatory and neurocytotoxic profiles, improved behavioral outcomes, decreased morbidity and, importantly, increased survival. RBC clearance efficacy was blocked by mechanosensitive channel antagonism and was effective when applied in anesthetized subjects, indicating a mechanosensitive channel mediated mechanism that does not depend on sensory stimulation or a specific neural activity pattern. Notably, this protocol qualifies for an FDA non-significant risk designation given its low intensity, making it readily clinically translatable. Overall, our results demonstrate that this low-intensity transcranial focused ultrasound protocol clears hemorrhage and other harmful substances from the brain via the meningeal lymphatic system, potentially offering a novel therapeutic tool for varied neurologic disorders.

bioengineering↗

bioRxiv2020

GEMC1-MCIDAS transcriptional program regulates multiciliogenesis in the choroid plexus and acts as a barrier to tumorigenesis

Multiciliated cells (MCCs) in the brain include the ependymal cells and choroid plexus (CP) epithelial cells. The CP secretes cerebrospinal fluid that circulates within the ventricular system, driven by ependymal cilia movement. However, the mechanisms and functional significance of multiciliogenesis in the CP remain unknown. Deregulated oncogenic signals cause CP carcinoma (CPC), a rare but aggressive pediatric brain cancer. Here we show that aberrant NOTCH and Sonic Hedgehog signaling in mice drive tumors that resemble CPC in humans. NOTCH-driven CP tumors were monociliated, whereas disruption of the NOTCH complex restored multiciliation and decreased tumor growth. NOTCH suppressed multiciliation in tumor cells by inhibiting the expression of GEMC1 and MCIDAS, early regulators of multiciliogenesis. Consistently, GEMC1-MCIDAS function is essential for multiciliation in the CP, and is critical for correcting multiciliation defect in tumor cells by a NOTCH inhibitor. Disturbances to the GEMC1 program are commonly observed in human CPCs characterized by solitary cilia. Consistently, CPC driven by deletion of Trp53 and Rb1 in mice exhibits a cilia deficit consequent to loss of Gemc1-Mcidas expression. Taken together, these findings reveal a GEMC1-MCIDAS multiciliation program in the CP critical for inhibiting tumorigenesis, and it may have therapeutic implications for the treatment of CPC.

cancer biology↗

bioRxiv2020

Non-canonical, potassium-driven cerebrospinal fluid clearance

Cerebrospinal fluid (CSF) provides vital support for the brain. Abnormal CSF accumulation is deleterious for perinatal neurodevelopment, but how CSF leaves the brain during this critical period is unknown. We found in mice a postnatal neurodevelopmental transition phase featuring precipitous CSF K+ clearance, accompanied by water, through the choroid plexus (ChP). The period corresponds to a human fetal stage when canonical CSF clearance pathways have yet to form and congenital hydrocephalus begins to manifest. Unbiased ChP metabolic and ribosomal profiling highlighted this transition phase with increased ATP yield and activated energy-dependent K+ transporters, in particular the Na+-K+-Cl- and water cotransporter NKCC1. ChP-targeted NKCC1 overexpression enhanced K+-driven CSF clearance and enabled more permissive cerebral hydrodynamics. Moreover, ventriculomegaly in an obstructive hydrocephalus model was improved by ChP-targeted NKCC1 overexpression. Collectively, we identified K+-driven CSF clearance through ChP during a transient but critical neurodevelopmental phase, with translational value for pathologic conditions.

neuroscience↗