Nanoparticles for the Targeted Delivery of Therapeutic Agents to the Brain for the Treatment of Dementias.

Lead Research Organisation: University College London
Department Name: Institute of Child Health


This project focuses on the development of nanotechnologies for the targeted delivery of novel therapies for Alzheimer's disease, the major cause of dementia in the elderly. The most common symptoms of dementias are gradual memory loss, confusion, and changes in personality, mood and behaviour. There are currently about 700,000 dementia patients in the UK and approximately 450,000 of those have Alzheimer's disease. There are no cures for dementias, only drugs that treat the symptoms and temporarily stabilize the disease progression so patients become more dependent on care. The cost of formal healthcare services (e.g., residential care, NHS support services) for dementia patients at 4Bn in 2002 are formidable, and expected to grow to 13Bn by 2031. However, when informal care contributions from families of patents are considered, estimated costs escalate to about 17Bn. There is a further economic and social toll from the impact of patient care on the careers of carers. Dementia is therefore a growing medical, social and economic problem for the UK and beyond. The current level of research activity into the understanding and treatment of dementias does not reflect the enormity of the growing challenge. Dementia is one of the major causes of disability in later life, contributing 11.2% of all years lived with disability over the age of 60, compared to 2.4% for cancer. Since 2002, however, only 1.4% of published research papers on disabilities concerned dementias, compared to 23.5% for cancers. Increased research funding and activity in dementias is therefore an urgent priority. We aim in this project to harness nanotechnologies for the design and delivery of new therapeutics for the treatment of Alzheimer's disease. Nanoparticles are formulations of synthetic, chemical components that self-assemble on mixing into particles of less than 100 nm. They can be used to package a variety of drugs, including genes, proteins and RNA molecules. The nanoparticle components that will be designed and synthesised will comprise novel peptides and lipids with smart properties, such as receptor targeting, stealth coatings, bioresponsive linkers for disassembly, and biocompatibility. The uptake of nanoparticles into the brain from the circulation is impeded by the blood brain barrier so we will optimise a method called convection enhanced delivery (CED). In CED the blood-brain barrier is physically bypassed by injecting reagents directly into the brain through a fine needle under constant pressure. CED has already been used to administer therapeutics, achieving widespread dispersal through the brain, but has not been optimised for nanoparticle delivery. The project combines basic studies into nanoparticle materials and biology of the brain in relation to CED, and more applied studies into nanoparticle formulation and CED-mediated dispersal studies using MRI. The output of this study will be a nanoparticle platform technology and delivery method compatible with a range of therapeutic options for Alzheimer's disease and other forms of dementia. The research team comprises scientific experts in chemistry, drug and nanoparticle formulations as well as clinical expertise in brain pathology, surgery and experimental clinical trials, and has the capabilities to succeed both in this project and a future Stage 2 therapeutic study into Alzheimer's disease. This new capability could transform the management of patients with dementias with enormous potential benefits to UK society and the economy.


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Description BACKGROUND

The aim of this project was to develop nanoparticles as carriers for the delivery of gene therapies to the brain, for the potential treatment of Alzheimer's disease. Possible gene therapies for Alzheimer's could target the formation of protein deposits (amyloid plaques, or neurofibrillary tangles) characteristic of the brains of Alzheimer's patients. We also aimed to develop nanoparticle formulations that can be imaged by magnetic resonance imaging (MRI). These technologies can then be used in future studies with specific therapeutic genes.


Administration of nanoparticles to the brain was performed by convection enhanced delivery (CED). In CED reagents are injected directly into the brain through a fine needle under constant pressure from a pump. CED has been used clinically but has not been optimised for nanoparticle delivery.

Nanoparticles were made from mixtures of peptides (synthetic protein fragments) and liposomes (synthetic fatty particles). The nanoparticles formed spontaneously on mixing the peptides and liposomes in precise ratios with the gene (DNA). The functions of the peptide component are to package the gene and to target the nanoparticle to brain cells. Liposomes enhance the efficiency of gene transfer within the cells. The genetic material may be a large piece of circular DNA (plasmid) for gene delivery or a small molecule of RNA (siRNA), for gene silencing.

Generally, nanoparticles for gene delivery have a very strong positive (cationic) surface charge, which enables binding to the negatively charged cell surface. We hypothesized for brain delivery by CED that negatively charged (anionic) nanoparticles should disperse more widely due to reduced binding to cells close to the injection site. We also investigated the potential for direct delivery by CED to rat brains of a protein, neprilysin, which degrades amyloid protein deposits in the Alzheimer's brain.


Initially, various lipids with different chemistries and properties were synthesised or purchased. Peptide design was adapted to optimise their dual functions of packaging and targeting to brain cells. These reagents were then used to make nanoparticles by simply mixing them with DNA or siRNA.

Nanoparticles were characterised for their size and charge as well as their efficiencies of gene delivery in cultured cells. Negatively-charged lipids combined with peptides in optimised proportions enabled the formulation of negative nanocomplexes with both siRNA and DNA. Branched peptides compared to linear peptides.showed some evidence for improved siRNA delivery but did not improve DNA delivery. Specific peptides targeted to brain cells , improved cell-specific targeting of the nanoparticles.

Labelling nanoparticles with the element gadolinium enabled detection of nanoparticles in rat brains by MRI and in histological samples by LA-ICP-MS, a sophisticated elemental imaging technique. Fluorescence microscopy was used to detect rhodamine-labelled nanoparticles. All analyses confirmed that anionic nanoparticles displayed greatly improved dispersal in brain by CED compared to cationic formulations. Anionic nanoparticle formulations in rat brains also displayed levels of gene expression and siRNA- mediated gene silencing similar to cationic formulations.

Neprilysin injected by CED displayed good dispersal and activity characteristics in rat brain, but PEGylation of the neprilysin, which can enhance protein stability and dispersal, had no beneficial effects.


1 Demonstration of widespread distribution in the brain of anionic nanoparticle siRNA and gene formulations delivered by CED.

2 Gene expression and gene silencing in brains by anionic, targeted nanoparticle formulations similar in levels to cationic formulations.

3 Brain imaging of nanoparticle distribution by MRI enabling live monitoring of treatment.

4 Tools for future studies to treat dementias with nucleic acids and proteins.
Exploitation Route We have developed and continue to develop further academic collaborations in developing nanoparticles for gene and siRNA delivery.

The technology has been licensed to a small British biotech company developing siRNA therapeutics for cancer - currently in preclinical evaluation.
Sectors Chemicals

Pharmaceuticals and Medical Biotechnology

Description AMR-CF Trust Project grant
Amount £149,062 (GBP)
Funding ID GN2299 
Organisation Action Medical Research 
Sector Charity/Non Profit
Country United Kingdom
Start 08/2014 
End 06/2016
Description CFF Project
Amount $293,000 (USD)
Organisation Cystic Fibrosis Foundation 
Sector Charity/Non Profit
Country United States
Start 03/2016 
End 03/2018
Title Anionic nanocomplexes for gene and siRNA delivery to the brain by CED 
Description Self assembling formulation of siRNA or DNA with novel lipid and peptide formulations for the production of self-assembling nanoparticles with a negative charge. This improves distribution in the brain. Also showed that a stealth coating of polyethylene glycol 
Type Of Material Technology assay or reagent 
Year Produced 2011 
Provided To Others? Yes  
Impact Use as a research tool in the labs of collaborators 
Description Advances in Nanotechnology for Drug Formulation", at the School of Pharmacy, London, organized by the Nanotechnology Knowledge Transfer Network (NanoKTN). 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Questions and answers

Year(s) Of Engagement Activity 2011
Description Nanoparticles and nanomedicine 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Professional Practitioners
Results and Impact Academic collaborations and contacts increased

Led to several short term research projects for UCL masters and undergraduate students in the field of nanoscience
Year(s) Of Engagement Activity 2011