CNS Gene Therapy and a Nexus of Complexity: Systems and Biology at a Crossroads

Brain targeting and toxicity study of odorranalectin-conjugated nanoparticles following intranasal administration

In order to improve brain uptake of nanoparticles following nasal administration, odorranalectin (OL), the smallest lectin with much less immunogenicity than other members of lectin family, was conjugated to the surface of poly (ethylene glycol)-poly (lactic-co-glycolic acid) (PEG-PLGA) nanoparticles (NP) in this study. The bioactivity of OL conjugated to the nanoparticles was verified by haemagglutination tests.Tissue distribution of OL-modified and unmodified nanoparticles (OL-NP and NP) was evaluated following intranasal (i.n.) administration by in vivo fluorescence imaging technique using DiR as a tracer, comparing with that of unmodified nanoparticles after intravenous (i.v.) injection. Besides, the nasal toxicity of OL-NP was evaluated on Calu-3 cell lines, toad palate and rat nasal mucosa.The results of TEM examination and dynamic light scattering showed a generally spherical shape of OL-NP with an average volume-based diameter around 90 nm. The haemagglutination test proved that OL retained its haemagglutination activity when conjugated to nanoparticles. The brain targeting indexes of NP and OL-NP following i.n. administration and NP following i.v. injection were 5.8, 11.6 and 0.08, respectively.Thus,i.n. administration demonstrated much better brain targeting efficiency than i.v. injection, and OL modification facilitated the nose-to-brain delivery of nanoparticles.Moreover, the toxicity assessment suggested good safety of OL-NP both in vitro and in vivo. In summary, odorranalectin-conjugated nanoparticle could be potentially used as a nose-to-brain drug delivery carrier for the treatment of CNS diseases.

Odorranalectin-conjugated nanoparticles: preparation, brain delivery and pharmacodynamic study on Parkinson's disease following intranasal administration

Odorranalectin (OL) was recently identified as the smallest lectin with much less immunogenicity than other members of the lectin family. In this study, to improve nose-to-brain drug delivery and reduce the immunogenicity of traditional lectin modified delivery system, OL was conjugated to poly(ethylene glycol)-poly(lactic-co-glycolic acid) (PEG-PLGA) nanoparticles and its biorecognitive activity on nanoparticles was verified by haemagglutination tests. Nose-to-brain delivery characteristic of OL-conjugated nanoparticles (OL-NP) was investigated by in vivo fluorescence imaging technique using DiR as a tracer. Besides, urocortin peptide (UCN), as a macromolecular model drug, was incorporated into nanoparticles and evaluated for its therapeutic efficacy on hemiparkinsonian rats following intranasal administration by rotation behavior test, neurotransmitter determination and tyrosine hydroxylase (TH) test. The results suggested that OL modification increased the brain delivery of nanoparticles and enhanced the therapeutic effects of UCN-loaded nanoparticles on Parkinson's disease. In summary, the OL-NPs could be potentially used as carriers for nose-to-brain drug delivery, especially for macromolecular drugs, in the treatment of CNS disorders.

Neurodegenerative disorders and nanoformulated drug development

Degenerative and inflammatory diseases of the CNS include, but are not limited to, Alzheimer's and Parkinson's disease, amyotrophic lateral sclerosis, stroke, multiple sclerosis and HIV-1-associated neurocognitive disorders. These are common, debilitating and, unfortunately, hold few therapeutic options. In recent years, the application of nanotechnologies as commonly used or developing medicines has served to improve pharmacokinetics and drug delivery specifically to CNS-diseased areas. In addition, nanomedical advances are leading to therapies that target CNS pathobiology and as such, can interrupt disordered protein aggregation, deliver functional neuroprotective proteins and alter the oxidant state of affected neural tissues. This article focuses on the pathobiology of common neurodegenerative disorders with a view towards how nanomedicine may be used to improve the clinical course of neurodegenerative disorders.

Nanotechnological applications for the treatment of neurodegenerative disorders

Nanotechnology employs engineered materials or devices that interact with biological systems at a molecular level and could revolutionize the treatment of neurodegenerative disorders (NDs) by stimulating, responding to and interacting with target sites to induce physiological responses while minimizing side-effects. Conventional drug delivery systems do not provide adequate cyto-architecture restoration and connection patterns that are essential for functional recovery in NDs, due to limitations posed by the restrictive blood-brain barrier. This review article provides a concise incursion into the current and future applications of nano-enabled drug delivery systems for the treatment of NDs, in particular Alzheimer's and Parkinson's diseases, and explores the application of nanotechnology in clinical neuroscience to develop innovative therapeutic modalities for the treatment of NDs.

Antisense RNA sequences modulating the ataxin-1 message: molecular model of gene therapy for spinocerebellar ataxia type 1, a dominant-acting unstable trinucleotide repeat disease

Spinocerebellar ataxia type 1 (SCA1) is a dominant inherited disease caused by expanded trinucleotide repeats resulting in an increased polyglutamine tract in the gene product. As a potential therapeutic approach for SCA1, we tested antisense RNAs targeting two regions of the ataxin-1 message. Single-stranded regions around the translational initiation site and the intron 8 splice donor site of the ataxin-1 message were identified by computer-assisted RNA secondary structure prediction. Plasmids were generated to contain a 254-bp antisense sequence spanning the translation initiation site (pLasBDini) or a 317-bp sequence spanning the intron 8 splice donor site (pLasBDei) of the ataxin-1 message. These plasmids were transfected into Chinese hamster ovary cells engineered to express either expanded or unexpanded ataxin-1 message and protein. Reduced levels of mutant ataxin-1 message (82 CAG repeats), wild-type ataxin-1 message (30 CAG repeats), and ataxin-1 protein were observed by Northern and Western blot analyses in pLasBDini-transfected clones. pLasBDei-transfected 293 cells exhibited a shift in ataxin-1 message to a size several kilobases longer than that of the natural message. Reverse transcriptase/polymerase chain reaction assays demonstrated the retention of message spanning the intron 8 splice acceptor and the inability to amplify sequences between exons 8 and 9, implying that normal splicing of intron 8 had been interrupted. We conclude that antisense RNAs were effective in reducing or modifying ataxin-1 messages in transfected cells, and may be an effective genetic strategy for therapy of SCA1 and similar dominant-acting neurological disorders.

Neurotrophic factors in autonomic nervous system plasticity and dysfunction

During development, neurotrophic factors are known to play important roles in regulating the survival of neurons in the autonomic nervous system (ANS) and the formation of their synaptic connectivity with their peripheral targets in the cardiovascular, digestive, and other organ systems. Emerging findings suggest that neurotrophic factors may also affect the functionality of the ANS during adult life and may, in part, mediate the effects of environmental factors such as exercise and dietary energy intake on ANS neurons and target cells. In this article, we describe the evidence that ANS neurons express receptors for multiple neurotrophic factors, and data suggesting that activation of those receptors can modify plasticity in the ANS. Neurotrophic factors that may regulate ANS function include brain-derived neurotrophic factor, nerve growth factor, insulin-like growth factors, and ciliary neurotrophic factor. The possibility that perturbed neurotrophic factor signaling is involved in the pathogenesis of ANS dysfunction in some neurological disorders is considered, together with implications for neurotrophic factor-based therapeutic interventions.

Nanomedicine in the diagnosis and therapy of neurodegenerative disorders

Neurodegenerative and infectious disorders including Alzheimer's and Parkinson's diseases, amyotrophic lateral sclerosis, and stroke are rapidly increasing as population's age. Alzheimer's disease alone currently affects 4.5 million Americans, and more than $100 billion is spent per year on medical and institutional care for affected people. Such numbers will double in the ensuing decades. Currently disease diagnosis for all disorders is made, in large measure, on clinical grounds as laboratory and neuroimaging tests confirm what is seen by more routine examination. Achieving early diagnosis would enable improved disease outcomes. Drugs, vaccines or regenerative proteins present "real" possibilities for positively affecting disease outcomes, but are limited in that their entry into the brain is commonly restricted across the blood-brain barrier. This review highlights how these obstacles can be overcome by polymer science and nanotechnology. Such approaches may improve diagnostic and therapeutic outcomes. New developments in polymer science coupled with cell-based delivery strategies support the notion that diseases that now have limited therapeutic options can show improved outcomes by advances in nanomedicine.