Fetal Gene Therapy Using a Single Injection of Recombinant AAV9 Rescued SMA Phenotype in Mice

Abstract

Symptoms of spinal muscular atrophy (SMA) disease typically begin in the late prenatal or the early postnatal period of life. The intrauterine (IU) correction of gene expression, fetal gene therapy, could offer effective gene therapy approach for early onset diseases. Hence, the overall goal of this study was to investigate the efficacy of human survival motor neuron (hSMN) gene expression after IU delivery in SMA mouse embryos. First, we found that IU-intracerebroventricular (i.c.v.) injection of adeno-associated virus serotype-9 (AAV9)-EGFP led to extensive expression of EGFP protein in different parts of the CNS with a great number of transduced neural stem cells. Then, to implement the fetal gene therapy, mouse fetuses received a single i.c.v. injection of a single-stranded (ss) or self-complementary (sc) AAV9-SMN vector that led to a lifespan of 93 (median of 63) or 171 (median 105) days for SMA mice. The muscle pathology and number of the motor neurons also improved in both study groups, with slightly better results coming from scAAV treatment. Consequently, fetal gene therapy may provide an alternative therapeutic approach for treating inherited diseases such as SMA that lead to prenatal death or lifelong irreversible damage.

Pre-natal manifestation of systemic developmental abnormalities in spinal muscular atrophy

“…Although these findings require validation in other mouse models of SMA, they extend our understanding of presymptomatic SMA. Our results suggest that effective delivery of therapy will likely require treatment in the presymptomatic phases of the disease, during the perinatal, or perhaps even prenatal, period in human patients ( 5 , 39 , 43 ). However, crucial ethical issues surround the use of human in utero gene therapy as a treatment strategy.…”

Therapeutic Approaches to Treat Mitochondrial Diseases: “One-Size-Fits-All” and “Precision Medicine” Strategies

“…For inherited genetic diseases, In-Utero Gene Therapy (IUGT) offers the potential of prophylaxis against early, irreversible, and lethal pathological change [ 413 ]. From a technical perspective, potential genetic therapeutic agents can be delivered to the fetus through infusion into the umbilical vein or via direct injection into the fetal organs.…”

“…injection of a single-stranded or self-complementary AAV9-SMN vector extended their lifespan of 93 (median of 63) or 171 (median 105) days. Both muscle pathology and motor neuron survival improved upon treatments, with slightly better results from scAAV administration [ 413 ].…”

CRISPR/Cas9-mediated correction of MITF homozygous point mutation in a Waardenburg syndrome 2A pig model

“…Similar to WS2A, which displays abnormalities of the retina as early as embryonic day 28 in pigs, there are several diseases that develop before birth and cause irreversible and fatal pathological change. In fetal mouse disease models, prenatal gene therapy has been exploited to prevent disease occurrence at the earliest stage as demonstrated by the treatment of hemophilia B, 67 acute neuronopathic Gaucher disease, 68 β-thalassaemia, 69 spinal muscular atrophy (SMA), 70 and hereditary tyrosinemia type 1, 55 indicating that prenatal gene editing is a promising approach for treating lethal diseases at the earliest stage. In the current study, we exploited the engineered BE (hA3A-eBE-Y130F) to correct the MITF c.740T>C mutation in SCNT-cloned embryos and demonstrated that efficient correction of this pathogenic mutation could be achieved through one-step microinjection of BE mRNA and sgRNA.…”