Efficient gene silencing in lungs and liver using imidazole-modified chitosan as a nanocarrier for small interfering RNA.

Despite high specificity and potency, small interfering RNA (siRNA)-based therapeutics have been limited by their poor biostability and intracellular penetration. Thus, effective nanocarriers that can protect and efficiently deliver siRNA to target cells in vivo are needed. Here we report on the efficiency of imidazole-modified chitosan (chitosan-imidazole-4-acetic acid [IAA])-siRNA nanoparticles to mediate gene silencing after administration via either intravenous (i.v.) or intranasal (i.n.) routes. Poly(ethylene glycol) (PEG)ylated nanoparticles for i.v. delivery demonstrated significant knockdown of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) enzyme in both lung and liver at as low as 1 mg/kg siRNA dose. In addition, the efficient, dose-dependent silencing of apolipoprotein B in the liver was also shown. For i.n. delivery, significant silencing of GAPDH protein expression was seen in the lungs with only 0.5 mg/kg/day siRNA delivered over 3 consecutive days. In summary, imidazole-modified chitosan-IAA nanoparticles are potentially effective carriers for siRNA delivery.

Identification of RNA linkage isomers by anion exchange purification with electrospray ionization mass spectrometry of automatically desalted phosphodiesterase-II digests.

Among the possible contaminants unique to RNA are linkage isomers that are difficult to identify by standard oligonucleotide analysis techniques. In a prior study, we used nonporous and monolithic polymer anion exchangers for purification and demonstrated a method to identify the presence of the linkage isomers. We also suggested a confirming technique employing phosphodiesterase-II (PDase-II), an enzyme incapable of cleaving 2'-5' linkages. We now present a method identifying the location of the linkage in the RNA isomer by anion exchange purification and electrospray ionization mass spectrometry (ESI-MS) of the digestion products. Because the ion-pair reversed-phase liquid chromatography (IP-RPLC) desalting methods we previously employed do not effectively separate oligonucleotides less than 6 bases from salt, we employed a direct reversed-phase method to automatically desalt the digestion products and then assessed the desalted digests by ESI-MS. The length and base composition of the fragments identified indicate that PDase-II cleaves up to and skips over the aberrant linkage and then resumes cleavage 1 or 2 bases to the 3' side of the 2'-5' linkage.

LNA incorporated siRNAs exhibit lower off-target effects compared to 2'-OMethoxy in cell phenotypic assays and microarray analysis.

Despite the promise of short interfering RNAs (siRNA), contending with off-target is a challenge for RNAi users. To alleviate these problems, we have developed locked nucleic acid (LNA) modified siRNAs and optimized performance using cellular phenotypic assays as well as microarray analysis. During development, we compared LNA and 2'OMethoxy (2'OMe) chemistries placed strategically throughout the siRNA molecule and found a novel pattern of LNA placement that greatly improved the specificity of the siRNA and reduced it's toxicity in culture while preserving the potency of the siRNA. The improvements in specificity made by LNA-modified siRNAs were developed and validated by measuring the phenotypic signatures in a high content cell-based screening assay as well as comparison of the level of differentially expressed genes observed in microarray analysis between modified and unmodified siRNAs. HT screening of a collection of genes demonstrated that the LNA-modified siRNAs exhibits the best overall rate to elicit the expected phenotype, reduced toxicity and achieved an improved coherence of phenotype compared to 2'OMe-modified or unmodified siRNAs.

Recent advancements in the treatment of lumbar radicular pain.

PURPOSE OF REVIEW: Lumbar radicular pain is a common and often difficult condition to treat. Current literature supports the theory that radicular pain is at least in part due to an inflammatory process involving cytokines, including tumor necrosis factor alpha and interleukins. This review summarizes some of the most recent research concerning the use of tumor necrosis factor alpha antagonists and interleukin receptor antagonists in the treatment of lumbar radicular pain. RECENT FINDINGS: Recent studies have shown promising results in the treatment of both acute and chronic lumbar radicular pain with tumor necrosis factor alpha antagonists such as etanercept and infliximab, as well as with interleukin receptor antagonists. SUMMARY: Treatment for lumbar radicular pain has long included epidural steroids to inhibit the inflammatory component of radicular pain. Recent studies have more precisely identified the cytokines responsible for this inflammatory process and indicate that inhibition of these cytokines may offer more specific and effective treatment for lumbar radicular pain.