Robust spinal motor neuron transduction following intrathecal delivery of AAV9 in pigs

Abstract

Adeno-associated viral vector 9 (AAV9) has recently been shown to penetrate the blood--brain barrier via intravascular administration, making it a good candidate for diffuse gene delivery. However, the potential side effects of systemic delivery are unknown. Intrathecal viral vector administration may be more invasive than intravenous injections, but it requires far less vector and it can be performed on an outpatient basis, making it an ideal route of delivery for clinical translation. A total of 12 domestic farm pigs (o20 kg) underwent a single-level lumbar laminectomy with intrathecal catheter placement for AAV9 delivery. Animals were perfused and the tissue was harvested 30 days after treatment. Gene expression was assessed by anti-green fluorescent protein immunohistochemistry. Although a single lumbar injection resulted in gene expression limited to the lumbar segment of the spinal cord, three consecutive boluses via a temporary catheter resulted in diffuse transduction of motor neurons (MNs) throughout the cervical, thoracic and lumbar spinal cords. We now present the first successful robust transduction of MNs in the spinal cord of a large animal via intrathecal gene delivery using a self-complementary AAV9. These promising results can be translated to many MN diseases requiring diffuse gene delivery.

Whole body correction of mucopolysaccharidosis IIIA by intracerebrospinal fluid gene therapy

“…Although this is a common clinical procedure, limited distribution of products in widespread CNS areas is achieved through this route. Preclinical data in pigs show that AAV9-derived gene expression following local lumbar intrathecal administration remains restricted to the areas of injection and that widespread spinal cord transduction requires several administrations of vector at the cervical, thoracic, and lumbar regions, suggesting that vector penetration occurs mostly in the vicinity of the catheter tip used for delivery (63). Global CNS gene delivery following intrathecal AAV administration has been documented in cynomolgus macaques, a nonhuman primate species of small size (~3-7 kg), using self-complementary AAV vectors diluted in a hyperosmotic buffer (64); while the study provides evidence that the approach is potentially feasible, detailed confirmatory studies in larger animal models are needed.…”

“…The results of these studies confirm the concept of unidirectional flow of CSF and suggest that i.c.v. administration of products may result in the most widespread distribution of drugs within CSF-containing compartments (63,65).…”

Erratum: Global CNS gene delivery and evasion of anti-AAV-neutralizing antibodies by intrathecal AAV administration in non-human primates

“…The methods of titering the NAbs were different in these studies, so we cannot comment on what level of NAb would be inhibitory in relation to our study. This NHP study yielded some notable differences compared to previous intrathecal AAV9 delivery studies in mice and pigs [13,15]. In pigs, the vector distribution was mostly limited to the lumbar spinal cord unless a catheter was manipulated to physically distribute the vector to the cervical and thoracic regions.…”

“…In our case, we utilized CSF volume as our comparative metric, assuming equivalent CSF volumes of 0.035 mL in mice, 0.09 mL in rats, 20 mL in pigs, 12-15 mL in NHPs, and 140 mL in humans [20][21][22]. In this case, the high dose in the referenced pig study (~1.5×10 11 vg per mL of CSF) [15] is equivalent to the low dose used in the present study in NHPs (~1.5×10 11 vg per mL of CSF). Again, it is unclear whether the increased peripheral biodistribution in NHPs compared to pigs is the result of physiological/anatomical differences, differential receptor biology and binding kinetics of AAV9, or differences in the injection protocol that could have led to vector leakage.…”

Restoration of Cytoskeleton Homeostasis After Gigaxonin Gene Transfer for Giant Axonal Neuropathy

“…AAV9 vector administration into the vein, lumbar intrathecal space, and cisterna magna have all been validated as ways to achieve broad CNS transgene delivery in large animal models (Duque et al, 2009;Federici et al, 2012;Gray et al, 2013). In the present study, cisterna magna injections were modeled in mice to investigate a potential therapeutic approach for GAN that might be translatable to humans.…”