Brain Endothelial AAV Gene Delivery Across the Blood-Brain Barrier
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Solution Overview
Problem
Current treatments for lysosomal storage diseases (LSDs), such as enzyme replacement therapy, fail to effectively target and treat the central nervous system (CNS) due to the inability of recombinant enzymes to cross the blood-brain barrier, leading to incomplete disease phenotypes and potential immune responses.
Innovation Solution
Development of recombinant adeno-associated virus (rAAV) capsids with modified n-mer motifs that enhance transduction of CNS vasculature endothelial cells, allowing for efficient delivery of therapeutic enzymes across the blood-brain barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If enzyme replacement therapy is used to treat lysosomal storage diseases, then enzyme deficiency is addressed, but the treatment fails to cross the blood-brain barrier to treat CNS phenotypes
Solution Approach 1:
The patent uses engineered AAV capsids as intermediary carriers to transport therapeutic enzymes across the blood-brain barrier. The capsid serves as a mediator that can traverse the BBB and deliver cargo to CNS cells, solving the barrier penetration problem of conventional enzyme replacement therapy.
Solution Approach 2:
The patent modifies the AAV capsid structure by changing amino acid parameters at specific positions (e.g., positions 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, 300, 305, 310, 315, 320, 325, 330, 335, 340, 345, 350, 355, 360, 365, 370, 375, 380, 385, 390, 395, 400, 405, 410, 415, 420, 425, 430, 435, 440, 445, 450, 455, 460, 465, 470, 475, 480, 485, 490, 495, 500, 505, 510, 515, 520, 525, 530, 535, 540, 545, 550, 555, 560, 565, 570, 575, 580, 585, 590, 595, 600, 605, 610, 615, 620, 625, 630, 635, 640, 645, 650, 655, 660, 665, 670, 675, 680, 685, 690, 695, 700, 705, 710, 715, 720, 725, 730, 735, 740, 745, 750, 755, 760, 765, 770, 775, 780, 785, 790, 795, 800, 805, 810, 815, 820, 825, 830, 835, 840, 845, 850, 855, 860, 865, 870, 875, 880, 885, 890, 895, 900, 905, 910, 915, 920, 925, 930, 935, 940, 945, 950, 955, 960, 965, 970, 975, 980, 985, 990, 995, 1000) to create capsid variants with enhanced BBB crossing capability and CNS tropism, enabling effective CNS enzyme replacement.
2Productivity
If direct intracerebral injection of AAV is used to deliver genes to CNS, then transduction efficiency improves, but the risk of infection and procedural complications increases
Solution Approach 1:
The patent uses AAV capsids as intermediary carriers that can be administered via safe routes (intravenous, intramuscular, subcutaneous) and cross the blood-brain barrier to reach CNS cells, eliminating the need for direct intracerebral injection and its associated risks while maintaining transduction efficiency.
Solution Approach 2:
The patent replaces the mechanical intervention of direct intracerebral injection with a biological transport mechanism where AAV capsids naturally cross the blood-brain barrier through endothelial cells, achieving CNS delivery through a safer, non-invasive route.
3Adaptability or versatility
If AAV vectors are used to treat LSDs with neurological involvement, then CNS targeting capability improves, but neurotoxicity may occur in compromised neural cells
Solution Approach 1:
The patent engineers AAV capsids with specific amino acid sequences that confer selective tropism for CNS endothelial cells and perivascular cells, enabling localized delivery to the vascular interface rather than direct neuronal transduction, thereby achieving CNS targeting while avoiding neurotoxicity in compromised neural cells.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modified rAAV capsids enable significant enzyme delivery to the CNS, reducing pathological substrate accumulation and improving treatment efficacy for LSDs with minimal immune response.
Implementation Method 1
the rAAV comprises a modified capsid comprising a n-mer motif that increases transduction of endothelial cells of the CNS vasculature
Data Source
AI summary
Applicants sought to express human iduronate-2-sulfatase (hIDS) in the brain endothelium of a mouse model of Mucopolysaccharidosis type II (MPSII, Hunter's syndrome) to enable enzyme secretion into the brain parenchyma. In this disorder, IDS deficiency results in the pathophysiological accumulation of heparan and dermatan sulfate GAGs. To test the hypothesis, Applicants chose AAV-BI30, an AAV9-derived capsid that has an enhanced in vivo tropism specific to the endothelium in the rodent CNS and can transduce human brain vascular endothelial cells in vitro more efficiently than AAV9. Applicants show that systemic delivery of AAV-BI30: hIDS restored IDS enzyme activity in the brain, liver, and serum of IDS-KO mice (FIG. 1). Importantly, AAV-BI30-mediated gene transfer resulted in the correction of GAG accumulation in the brain (FIG. 2). This effect was not observed when using the AAV-BI30 vector packaging a non-secreting version of hIDS. These findings highlight that targeting endothelial cells throughout the CNS is a promising approach for delivering enzymes across the BBB and restoring lysosomal metabolism.