Design and biological activity of novel stealth polymeric lipid nanoparticles for enhanced delivery of hydrophobic photodynamic therapy drugs

Advances in in vivo stability and preferential tumor uptake of cancer nanomedicine are warranted for effective chemotherapy. Here, we describe a novel nanoformulation using an unconventional polymeric tubule-forming phospholipid, DC8,9PC. We report that DC8,9PC transitions to stable vesicles (LNPs) in the presence of PEGylated lipid (DSPE-PEG2000); the resulting DC8,9PC:DSPE-PEG2000 LNPs efficiently included a hydrophobic PDT drug, HPPH. Remarkably, these LNPs incorporated unusually high DSPE-PEG2000 concentrations; LNP10-HPPH and LNP20-HPPH (10 & 20 mol% PEGylated lipid, respectively) exhibited >90% serum stability at 37 °C. Increased PEGylation in the LNPs correlated with enhanced tumor accumulation in intravenously injected HT29 tumor mouse xenographs. Colon-26 bearing BALB/c mice, intravenously injected with LNP20-HPPH showed superior PDT efficacy and animal survival (no tumor recurrence up to 100 days) as compared to a formulation currently used in clinical trials. Taken together, we present a simple stealth binary lipid nanosystem with enhanced efficiency of tumor accumulation and superior therapeutic efficacy.

BDNF variation and mood disorders: a novel functional promoter polymorphism and Val66Met are associated with anxiety but have opposing effects

The brain-derived neurotrophic factor (BDNF) gene is critical for neuronal function and survival, and is likely to be important in psychiatric disorders. In this study, we used single-nucleotide polymorphism (SNP) discovery, functional analyses, and genetic association studies to better understand the potential role of BDNF sequence variation in behavior. Screening 480 unrelated individuals for SNPs and genotyping was performed in US Caucasian, American Indian, and African American populations. Lifetime DSM-III-R psychiatric diagnoses were assigned and the Tridimensional Personality Questionnaire (TPQ) was administered to measure anxious temperament (harm avoidance (HA)) and novelty seeking (NS). A novel SNP (-281 C>A) in promoter 1 was discovered that had decreased DNA binding in vitro and decreased basal reporter gene activity in transfected rat hippocampal neurons. The frequency of the -281 A allele was 0.03 in a Caucasian sample, but was virtually absent in other populations. Association analyses in a community-based sample showed that individuals with the -281 A allele (13 heterozygotes) had lower TPQ HA (F=4.8, p<0.05). In contrast, the Met 66 allele was associated with increased HA (F=4.1, p=0.02) and was most abundant in individuals with both anxiety disorders and major depression (p<0.05). Among the Val66Val homozygotes, individuals who were -281 CA heterozygotes had significantly lower HA than the -281 CC homozygotes (p<0.01). Our results suggest that in this population, the low activity -281 A allele may be protective against anxiety and psychiatric morbidity, whereas Met 66 may be a risk allele.

Genomics and variation of ionotropic glutamate receptors: implications for neuroplasticity

We used two approaches to identify sequence variants in ionotropic glutamate receptor (IGR) genes: high-throughput screening and resequencing techniques, and "information mining" of public (e.g. dbSNP, ENSEMBL) and private (i.e. Celera Discovery System) sequence databases. Each of the 16 known IGRs is represented in these databases, their positions on a canonical physical map are established. Comparisons of mouse, rat, and human sequences revealed substantial conservation among these genes, which are located on different chromosomes but found within syntenic groups of genes. The IGRs are members of a phylogenetically ancient gene family, sharing similarities with glutamate-like receptors in plants. Parsimony analysis of amino acid sequences groups the IGRs into three distinct clades based on ligand-binding specificity and structural features, such as the channel pore and membrane spanning domains. A collection of 38 variants with amino acid changes was obtained by combining screening, resequencing, and informatics approaches for several of the IGR genes. This represents only a fraction of the sequence variation across these genes, but in fact these may constitute a large fraction of the common polymorphisms at these genes and these polymorphisms are a starting point for understanding the role of these variants in function. Genetically influenced human neurobehavioral phenotypes are likely to be linked to IGR genetic variants. Because ionotropic glutamate receptor activation leads to calcium entry, which is fundamental in brain development and in forms of synaptic plasticity essential for learning and memory and is essential for neuronal survival, it is likely that sequence variants in IGR genes may have profound functional roles in neuronal activation and survival mechanisms.