This proposal outlines a research study to investigate the efficacy of intravenous (IV) lecanemab in reducing amyloid-beta (A$\beta$) plaque in rats exposed to microgravity, both with and without focused ultrasound (FUS) to transiently open the blood-brain barrier (BBB). The study aims to assess the implications of these findings for astronauts undertaking long-duration missions to Mars, where microgravity exposure and potential neurodegenerative risks are significant concerns.

According to www.iAsk.Ai - Ask AI:

Background and Rationale

Long-duration space missions, such as those to Mars, expose astronauts to unique physiological stressors, including microgravity, radiation, and altered circadian rhythms. Emerging research suggests that prolonged exposure to microgravity may contribute to neurocognitive deficits and potentially accelerate neurodegenerative processes.[1] While the exact mechanisms are still being elucidated, changes in cerebral blood flow, intracranial pressure, and oxidative stress in microgravity environments are hypothesized to play a role in brain health.[2]

Amyloid-beta (A$\beta$) plaque accumulation in the brain is a hallmark pathology of Alzheimer's disease (AD) and is associated with cognitive decline.[3] Recent evidence indicates that neuroinflammation and impaired waste clearance mechanisms, which can be exacerbated by stress and environmental factors, may contribute to A$\beta$ pathology.[4] Given the unique stressors of spaceflight, it is plausible that astronauts could be at an increased risk for accelerated A$\beta$ accumulation or impaired clearance.

Lecanemab is a humanized monoclonal antibody that selectively binds to and clears soluble aggregated A$\beta$ protofibrils, thereby reducing A$\beta$ plaque in the brain.[5] It has demonstrated clinical efficacy in slowing cognitive decline in early AD.[6] However, the blood-brain barrier (BBB) presents a significant challenge for the delivery of large molecules like antibodies to the brain. Focused ultrasound (FUS), when applied with microbubbles, can transiently and non-invasively open the BBB, enhancing drug delivery to targeted brain regions.[7] This technique has shown promise in preclinical and clinical studies for improving the delivery of various therapeutic agents, including antibodies, to the brain.[8]

This study proposes to investigate the potential of lecanemab, both alone and in combination with FUS-mediated BBB opening, to mitigate A$\beta$ pathology in a microgravity analog. The findings will provide crucial insights into potential countermeasures for neurodegenerative risks in astronauts on long-duration missions.

Research Objectives

1. To evaluate the efficacy of intravenous lecanemab in reducing A$\beta$ plaque burden in the brains of rats exposed to simulated microgravity.
2. To determine if focused ultrasound (FUS) mediated blood-brain barrier opening enhances the delivery and efficacy of lecanemab in reducing A$\beta$ plaque in microgravity-exposed rats.
3. To assess the impact of microgravity on A$\beta$ pathology and neuroinflammatory markers in rat brains.
4. To explore the implications of these findings for the development of therapeutic strategies to protect astronaut brain health during long-duration space missions.

Methodology

Animal Model and Microgravity Simulation

Rats will be housed in a simulated microgravity environment using the hindlimb unloading (HU) model, a widely accepted ground-based analog for microgravity.[9] Male Sprague-Dawley rats (n=80) will be randomly assigned to one of five groups (n=16 per group):

1. Ground Control (GC): Normal housing, no HU, no treatment.
2. Microgravity Control (MC): HU, no treatment.
3. Lecanemab Only (LO): HU, IV lecanemab.
4. FUS Only (FO): HU, FUS, no lecanemab.
5. Lecanemab + FUS (LF): HU, IV lecanemab, FUS.

Rats will undergo HU for a period of 28 days to induce microgravity-related physiological changes. This duration is sufficient to observe changes in bone density, muscle atrophy, and neurovascular adaptations relevant to microgravity exposure.[10]

Lecanemab Administration

Lecanemab will be administered intravenously at a dose of 10 mg/kg twice weekly, consistent with preclinical studies and human dosing regimens adjusted for species differences.[11] The treatment will commence after 7 days of HU to allow for initial microgravity adaptation and continue for the remaining 21 days of the HU period.

Focused Ultrasound (FUS) Application

For the FUS groups (FO and LF), FUS will be applied to specific brain regions (e.g., hippocampus, cortex) known to be susceptible to A$\beta$ accumulation. A clinical FUS system (e.g., Exablate Neuro, Insightec) adapted for small animal use, or a dedicated small animal FUS system, will be utilized. Microbubbles (e.g., Definity, Lumason) will be administered intravenously immediately prior to FUS application to facilitate BBB opening.[12] FUS parameters (frequency, pressure, pulse duration, sonication time) will be optimized to achieve transient and safe BBB opening without causing tissue damage, based on established protocols.[13] FUS will be applied once weekly, immediately prior to lecanemab administration, for a total of three FUS sessions.

Outcome Measures

At the end of the 28-day HU period, rats will be euthanized, and their brains will be harvested for comprehensive analysis.

• A$\beta$ Plaque Quantification: Brain tissue will be sectioned and stained with antibodies specific for A$\beta$ (e.g., 6E10, 4G8) to quantify plaque burden using immunohistochemistry and image analysis software (e.g., ImageJ, Halo).[14]
• Lecanemab Brain Penetration: ELISA or mass spectrometry will be used to quantify lecanemab concentrations in brain tissue to assess BBB penetration in the FUS-treated groups.[15]
• Neuroinflammation Markers: Immunohistochemistry and Western blot will be used to assess markers of neuroinflammation (e.g., GFAP for astrogliosis, Iba1 for microglial activation, TNF-$\alpha$, IL-6).[16]
• Synaptic Integrity Markers: Western blot will be used to assess synaptic markers (e.g., synaptophysin, PSD-95) as indicators of synaptic health.[17]
• BBB Integrity Assessment: Evans Blue extravasation or gadolinium-enhanced MRI will be used to confirm transient BBB opening in FUS-treated groups and assess long-term BBB integrity.[18]
• Behavioral Assessment (Optional): If resources permit, a subset of rats could undergo behavioral testing (e.g., novel object recognition, Morris Water Maze) to assess cognitive function, though the primary focus is on pathological changes.

Statistical Analysis

Data will be analyzed using appropriate statistical methods, including one-way ANOVA with post-hoc tests (e.g., Tukey's HSD) to compare differences between groups. A p-value of < 0.05 will be considered statistically significant.

Timeline

• Months 1-2: IACUC approval, animal procurement, facility setup.
• Months 3-4: Pilot studies for FUS parameters and lecanemab dosing in normal rats.
• Months 5-8: Main experimental phase (HU, treatments, tissue collection).
• Months 9-12: Tissue processing, biochemical analyses, data analysis.
• Months 13-14: Manuscript preparation and submission.
• Months 15-16: Dissemination of findings (conferences, reports to NASA).

Expected Outcomes and Significance

This study is expected to provide critical data on the potential of lecanemab, particularly when combined with FUS, to mitigate A$\beta$ pathology in a microgravity environment.

• Successful A$\beta$ reduction: We hypothesize that lecanemab will reduce A$\beta$ plaque burden in microgravity-exposed rats, and that FUS will enhance this effect by improving lecanemab delivery to the brain.
• Understanding microgravity effects: The study will shed light on how microgravity influences A$\beta$ accumulation and neuroinflammation, providing a better understanding of the neurobiological risks of spaceflight.
• Translational implications for astronauts: The findings will directly inform the development of potential countermeasures for neurodegenerative risks in astronauts on long-duration missions. If successful, this research could pave the way for future clinical trials in astronauts, potentially leading to the use of lecanemab or similar therapies to protect brain health during deep-space exploration.
• Advancement of FUS technology: The study will further validate FUS as a safe and effective method for enhancing drug delivery to the brain in challenging physiological conditions.

Facilities and Resources

The study will be conducted at the University of Pittsburgh, utilizing state-of-the-art animal facilities, a dedicated focused ultrasound laboratory, and core facilities for histology, immunohistochemistry, and biochemical analyses. Dr. David Barckhoff, as Principal Investigator, has extensive experience in neurodegenerative disease research, drug delivery, and preclinical models.

Cost Estimates

The following are estimated costs for a 16-month project. These are approximate and may vary based on vendor pricing and specific institutional rates.

Personnel Costs (FTE - Full-Time Equivalent)

• Principal Investigator (David Barckhoff): 10% FTE for 16 months (salary + fringe benefits) - $30,000
• Postdoctoral Researcher (1.0 FTE): 16 months (salary + fringe benefits) - $100,000
• Research Technician (0.5 FTE): 16 months (salary + fringe benefits) - $40,000
• Total Personnel: $170,000

Animal Costs

• Sprague-Dawley Rats (n=80): $50/rat = $4,000
• Animal Housing (28 days/rat): $5/cage/day x 20 cages x 28 days = $2,800
• Total Animal Costs: $6,800

Reagents and Consumables

• Lecanemab (preclinical grade): Estimated based on 10 mg/kg, 80 rats, multiple doses - $15,000
• Microbubbles (for FUS): $2,000
• Antibodies (A$\beta$, GFAP, Iba1, etc.): $5,000
• ELISA/Western Blot Kits: $3,000
• Histology Reagents (dyes, mounting media): $2,000
• General Lab Supplies (gloves, pipettes, tubes): $5,000
• Total Reagents & Consumables: $32,000

Equipment Usage/Maintenance

• Focused Ultrasound System Usage: (If not owned, rental/usage fees) - $10,000
• Microscope Usage/Image Analysis Software License: $3,000
• Animal Anesthesia/Monitoring Equipment: $2,000
• Total Equipment Usage: $15,000

Publication and Dissemination

• Open Access Publication Fees: $3,000
• Conference Travel (2 conferences): $4,000
• Total Publication & Dissemination: $7,000

Indirect Costs (F&A - Facilities & Administrative)

• Calculated at 50% of Modified Total Direct Costs (MTDC):
  • MTDC = Personnel + Animal + Reagents + Equipment + Publication = $170,000 + $6,800 + $32,000 + $15,000 + $7,000 = $230,800
  • Indirect Costs = 0.50 x $230,800 = $115,400

Total Estimated Project Cost:

• Direct Costs: $230,800
• Indirect Costs: $115,400
• Grand Total: $346,200

The total estimated cost for this 16-month research project is approximately $346,200. This budget provides a comprehensive overview of the resources required to successfully execute the proposed research and achieve the stated objectives.

References

Answer Provided by iAsk.ai – Ask AI.