ABSTRACT
A method using multi-mode solid-phase extraction and ultra-high-performance liquid chromatography (UHPLC)-electrospray mass spectrometry was developed to quantify Dicer-substrate small interfering RNA (DsiRNA) directed against the hypoxanthine phosphoribosyltransferase 1 (HPRT1) gene transcript in mouse liver tissue. The oligonucleotides were separated into sense and antisense strands using a UHPLC C(18) column with mobile phases containing 1,1,1,3,3,3-hexafluoro-2-propanol in both water (mobile phase A) and methanol (mobile phase B) with triethylamine as the ion pairing agent at a column temperature of 65°C. The lower limits of detection for the sense and antisense strands were ~1 ng/mg. The dynamic ranges for the sense and antisense strands were 5 ng/mg-1,000 ng/mg and 1 ng/mg-1,000 ng/mg, respectively. The lower limits of quantification for the sense and antisense strands were 5 ng/mg and 1 ng/mg, respectively, each with a relative standard deviation <15% over the range of calibration curve with sufficient precision and accuracy. Oligonucleotides were quantified at different time intervals after intravenous administration of living mice with lipid nanoparticle formulated HPRT1 DsiRNA and were detected as early as 15 min after administration, but not detected beyond the 24 h time point.
Subject(s)
Chromatography, High Pressure Liquid/methods , Hypoxanthine Phosphoribosyltransferase/metabolism , RNA, Small Interfering/metabolism , Ribonuclease III/metabolism , Specimen Handling/methods , Spectrometry, Mass, Electrospray Ionization/methods , Animals , Female , Liver/metabolism , Mice , Ribonuclease III/geneticsABSTRACT
BACKGROUND/AIMS: Hyperoxaluria is a major risk factor for recurrent urolithiasis and nephrocalcinosis. We tested an oral therapy with a crystalline, cross-linked formulation of oxalate-decarboxylase (OxDc-CLEC) on the reduction of urinary oxalate and decrease in the severity of kidney injury in two models: AGT1 knockout mice (AGT1KO) in which hyperoxaluria is the result of an Agxt gene deficiency, and in AGT1KO mice challenged with ethylene glycol (EG). METHODS: Four different doses of OxDc-CLEC mixed with the food, or placebo were given to AGT1KO mice (200 mg/day, n = 7) for 16 days and to EG-AGT1KO mice (5, 25, and 80 mg, n = 11) for 32 days. RESULTS: Oral therapy with 200 mg OxDc-CLEC reduced both urinary (44%) and fecal oxalate (72%) in AGT1KO mice when compared to controls. Similarly, in EG-AGT1KO mice, each of the three doses of OxDc-CLEC produced a 30-50% reduction in hyperoxaluria. A sustained urinary oxalate reduction of 40% or more in the 80 mg group led to 100% animal survival and complete prevention of nephrocalcinosis and urolithiasis. CONCLUSION: These data suggest that oral therapy with OxDc-CLEC may reduce hyperoxaluria, prevent calcium oxalate nephrocalcinosis and urolithiasis, and can represent a realistic option for the treatment of human hyperoxaluria, independent of cause.
