In Utero Gene Therapy and Genome Editing

InUtero Gene Therapy: Progress and Challenges

In utero gene therapy has the potential to treat lethal and morbid perinatal diseases before birth. Small fetal size, a tolerogenic immune system, and dosing efficiency make the fetus a compelling patient. Numerous clinical, social, and institutional factors must be considered to achieve the promise of genetic treatment before birth.

Delivery technologies for in utero gene therapy

Advances in prenatal imaging, molecular diagnostic tools, and genetic screening have unlocked the possibility to treat congenital diseases in utero prior to the onset of clinical symptoms. While fetal surgery and in utero stem cell transplantation can be harnessed to treat specific structural birth defects and congenital hematological disorders, respectively, in utero gene therapy allows for phenotype correction of a wide range of genetic disorders within the womb. However, key challenges to realizing the broad potential of in utero gene therapy are biocompatibility and efficiency of intracellular delivery of transgenes. In this review, we outline the unique considerations to delivery of in utero gene therapy components and highlight advances in viral and non-viral delivery platforms that meet these challenges. We also discuss specialized delivery technologies for in utero gene editing and provide future directions to engineer novel delivery modalities for clinical translation of this promising therapeutic approach.

In Utero Gene Therapy (IUGT) Using GLOBE Lentiviral Vector Phenotypically Corrects the Heterozygous Humanised Mouse Model and Its Progress Can Be Monitored Using MRI Techniques

In utero gene therapy (IUGT) to the fetal hematopoietic compartment could be used to treat congenital blood disorders such as β-thalassemia. A humanised mouse model of β-thalassemia was used, in which heterozygous animals are anaemic with splenomegaly and extramedullary hematopoiesis. Intrahepatic in utero injections of a β globin-expressing lentiviral vector (GLOBE), were performed in fetuses at E13.5 of gestation. We analysed animals at 12 and 32 weeks of age, for vector copy number in bone marrow, peripheral blood liver and spleen and we performed integration site analysis. Compared to noninjected heterozygous animals IUGT normalised blood haemoglobin levels and spleen weight. Integration site analysis showed polyclonality. The left ventricular ejection fraction measured using magnetic resonance imaging (MRI) in treated heterozygous animals was similar to that of normal non-β-thalassemic mice but significantly higher than untreated heterozygous thalassemia mice suggesting that IUGT ameliorated poor cardiac function. GLOBE LV-mediated IUGT normalised the haematological and anatomical phenotype in a heterozygous humanised model of β-thalassemia.

Treatment of heritable diseases using CRISPR: Hopes, fears, and reality

CRISPR gene editing is poised to transform the therapeutic landscape for diseases of genetic origin. The ease and agility by which CRISPR can make specific changes to DNA holds great promise not only for the treatment of heritable diseases, but also their prevention through germline editing. CRISPR-based therapeutic strategies are currently under development for numerous monogenic diseases. These strategies range from proof of concept studies demonstrating pre-fertilization gamete editing to recently initiated clinical trials for postnatal ex vivo therapies. The promise of CRISPR's human genome editing potential has captivated the public's attention. It is of paramount importance that medical professionals who work with patients who may have or carry a monogenic heritable disease understand CRISPR technology in order to have informed and compassionate discussions with their patients. Understanding CRISPR means understanding its evolving therapeutic applications' nuances, limitations, and barriers to access as well as the regulatory landscape they inhabit. In this piece we provide a review of the promises and pitfalls of CRISPR germline gene editing and their implications for patient decision-making throughout various stages of the reproductive process.