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Title:
Developing brain-targeting lipid nanoparticles for translational RNA applications: proof of concept in creatine transporter deficiency.
Supervisors:
Julien Baruteau and Naresh Hanchate
Project Description:
Background
Among 3,000 cerebral genetic diseases, 75% of them affect children causing severe morbidity and early death. Cerebral inherited metabolic diseases (CIMD) are caused by the disruption of essential biochemical pathways, causing mostly diffuse neurological diseases. Less than 5% of these diseases have approved disease-changing therapies. Therefore, there is high unmet need for novel therapies.
Gene therapy applications mediated by viral vectors (GT-VV) have achieved clinical successes in various diseases but they have limitations including ongoing adverse events such as immunogenicity and insertional mutagenesis. Due to these potential adverse events, GT-VV-treated patients are often underdosed and do not have a full correction of the diseases and remain with severe neurodebilitating disease.
Messenger RNA (mRNA) replacement therapy is a novel gene therapy technology, which has shown its potent efficacy and high safety profile during the COVID-19 pandemic. mRNA therapy is actively being developed in many areas including rare genetic diseases. mRNA is encapsulated in lipid nanoparticles (LNPs) to prevent rapid degradation by RNases. Neither mRNA nor LNP trigger sustained immune response, enabling successful re-administration and adaptation of doses, overcoming GT-VV limitations. LNPs composition modify their biodistribution and improves efficacy. In vitro LNP screening does not correlate with in vivo findings.
Creatine is an essential molecule for storage and transmission of phosphate-bound energy. X-linked creatine transporter deficiency, caused by deficiency of the SLC6A8 gene, causes a severe epileptic encephalopathy with autism and behavioural disturbances. It is thought to represent 1-2% of intellectual disability in males. Standard of care relies on arginine/glycine supplementation with marginal modifications of the phenotype, with persistent significant unmet needs.
Aim
mRNA-LNP has a transformative potential for cerebral monogenic diseases. The aim of this project is to screen for an optimal LNP able to target the brain and show proof of concept in creatine transporter deficiency.
Objectives
Objective 1: Development and characterisation of LNP library
Creation of a library of barcoded mRNAs encapsulated in LNPs with different composition and addition of published and novel peptide-targeting ligands specific for neuronal cells and blood brain barrier crossing.
Objective 2: Development and validation of neuronal-targeting scRNAseq-based screening
In vivo screening using single cell RNA sequencing (scRNAseq) following intracerebroventricular and systemic injections, the latter testing blood brain barrier crossing.
Objective 3: Validation in CIMD mouse model, creatine transporter deficiency
Proof of concept in a mouse model of creatine transporter deficiency to test the therapeutic effect of this optimised LNP construct after mRNA SLC6A8 optimisation
Methods
Objective 1: Molecular biology, cloning, cell culture, mRNA-LNP production and characterisation
Objective 2: FACS, scRNAseq (from library preparation to post-processing and analysis), immunostaining.
Objective 3: Animal work, genotyping, behaviour tests, immunostaining, mass spectrometry
Timelines
Objective 1: Months 1-12
Objective 2: Months 13-24
Objective 3: Months 18-30
Thesis writing: Months 30-36
References
About inherited creatine transporter deficiency
1. Li et al, Brain Sci 2023
About LNP-mRNA
2. Grant-Serroukh et al. J Control Release 2022
3. Gurung et al.2024, Sci Trans Med 2024
About single cell transcriptomics
4. Hanchate et al. Science 2015
5. Hanchate et al. PNAS 2020
Contact Information:
Julien Baruteau