Limits...
Onset Time and Durability of Huntingtin Suppression in Rhesus Putamen After Direct Infusion of Antihuntingtin siRNA.

Grondin R, Ge P, Chen Q, Sutherland JE, Zhang Z, Gash DM, Stiles DK, Stewart GR, Sah DW, Kaemmerer WF - Mol Ther Nucleic Acids (2015)

Bottom Line: After a 1-week washout period, monkeys received radiolabeled siRNA targeting huntingtin.After 1 or 3 days of siRNA delivery, monkeys were either terminated, or their pumps were shut off and they were terminated 10 or 24 days later.These findings indicate the rapid onset and durability of siRNA-mediated target gene suppression observed in other organs also occurs in the brain, and support the use of episodic delivery of siRNA into the brain for treatment of Huntington's disease and possibly other neurodegenerative diseases.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, USA.

ABSTRACT
One possible treatment for Huntington's disease involves direct infusion of a small, interfering RNA (siRNA) designed to reduce huntingtin expression into brain tissue from a chronically implanted programmable pump. Here, we studied the suppression of huntingtin mRNA achievable with short infusion times, and investigated how long suppression may persist after infusion ceases. Rhesus monkeys received 3 days of infusion of Magnevist into the putamen to confirm catheter patency and fluid distribution. After a 1-week washout period, monkeys received radiolabeled siRNA targeting huntingtin. After 1 or 3 days of siRNA delivery, monkeys were either terminated, or their pumps were shut off and they were terminated 10 or 24 days later. Results indicate that the onset of huntingtin mRNA suppression in the rhesus putamen occurs rapidly, achieving a plateau throughout the putamen within 4 days. Conversely, loss of huntingtin suppression progresses slowly, persisting an estimated 27-39 days in the putamen and surrounding white matter. These findings indicate the rapid onset and durability of siRNA-mediated target gene suppression observed in other organs also occurs in the brain, and support the use of episodic delivery of siRNA into the brain for treatment of Huntington's disease and possibly other neurodegenerative diseases.

No MeSH data available.


Related in: MedlinePlus

Suppression of HTT mRNA in the putamen. Average percent suppression of HTT mRNA in tissue punches from outside the putamen or from within the putamen, by treatment group, after subtracting the average percent suppression at the corresponding tissue punch locations in phosphate-buffered saline Group 1. Treatment and punch location combinations that are significantly different by post-hoc analysis (Tukey method15): n.s. = not significantly different; **P < 0.01. HTT, huntingtin.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4561652&req=5

fig3: Suppression of HTT mRNA in the putamen. Average percent suppression of HTT mRNA in tissue punches from outside the putamen or from within the putamen, by treatment group, after subtracting the average percent suppression at the corresponding tissue punch locations in phosphate-buffered saline Group 1. Treatment and punch location combinations that are significantly different by post-hoc analysis (Tukey method15): n.s. = not significantly different; **P < 0.01. HTT, huntingtin.

Mentions: Using HTT suppression measurements normalized to the corresponding PBS group averages (on a punch location-by-punch-location basis), a mixed-model analysis of variance (ANOVA) of HTT suppression with punch location as the within-monkey factor and membership in groups receiving siRNA for zero (PBS group), 1, or 3 days as the between monkey factor was performed. Two outlier observations (with standardized residuals more than 5.0 standard deviations from their respective group mean) were omitted from the analysis: one punch from one monkey in the PBS group (calculated percent suppression = −96.13%, i.e., an apparent increase in HTT expression) and one punch from one monkey in the siRNA1+3 group (calculated percent suppression = −52.20%, also indicating an apparent increase in HTT expression). The ANOVA resulted in a significant difference among punch locations (F = 2.12, df = 68, 359, P < 0.001) and a significant interaction effect of punches by treatment group (F = 1.35, df = 136, 359, P = 0.015), indicating there is evidence for true differences in the level of HTT mRNA suppression at various anatomical sites depending upon the treatment administered, as expected. To further characterize the relationship between level of HTT mRNA suppression, location in the brain, and treatment group, the punches were categorized according to whether they were within or outside the putamen (the site of the infusion), and a mixed-model ANOVA was performed with membership in groups receiving siRNA for zero (PBS group), 1, or 3 days as the between-monkey factor, and punch category (within or outside the putamen) as a within-monkey factor, with punches nested within punch category. The ANOVA resulted in a significant interaction between punch category and treatment group (F = 14.99, df = 2, 493, P < 0.001). This interaction is portrayed in the graph in Figure 3, which shows no differences among the monkeys receiving PBS or siRNA in HTT mRNA suppression in locations outside the putamen, but a difference among the monkeys receiving PBS or siRNA for differing lengths of time in HTT mRNA suppression in locations within the putamen.


Onset Time and Durability of Huntingtin Suppression in Rhesus Putamen After Direct Infusion of Antihuntingtin siRNA.

Grondin R, Ge P, Chen Q, Sutherland JE, Zhang Z, Gash DM, Stiles DK, Stewart GR, Sah DW, Kaemmerer WF - Mol Ther Nucleic Acids (2015)

Suppression of HTT mRNA in the putamen. Average percent suppression of HTT mRNA in tissue punches from outside the putamen or from within the putamen, by treatment group, after subtracting the average percent suppression at the corresponding tissue punch locations in phosphate-buffered saline Group 1. Treatment and punch location combinations that are significantly different by post-hoc analysis (Tukey method15): n.s. = not significantly different; **P < 0.01. HTT, huntingtin.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561652&req=5

fig3: Suppression of HTT mRNA in the putamen. Average percent suppression of HTT mRNA in tissue punches from outside the putamen or from within the putamen, by treatment group, after subtracting the average percent suppression at the corresponding tissue punch locations in phosphate-buffered saline Group 1. Treatment and punch location combinations that are significantly different by post-hoc analysis (Tukey method15): n.s. = not significantly different; **P < 0.01. HTT, huntingtin.
Mentions: Using HTT suppression measurements normalized to the corresponding PBS group averages (on a punch location-by-punch-location basis), a mixed-model analysis of variance (ANOVA) of HTT suppression with punch location as the within-monkey factor and membership in groups receiving siRNA for zero (PBS group), 1, or 3 days as the between monkey factor was performed. Two outlier observations (with standardized residuals more than 5.0 standard deviations from their respective group mean) were omitted from the analysis: one punch from one monkey in the PBS group (calculated percent suppression = −96.13%, i.e., an apparent increase in HTT expression) and one punch from one monkey in the siRNA1+3 group (calculated percent suppression = −52.20%, also indicating an apparent increase in HTT expression). The ANOVA resulted in a significant difference among punch locations (F = 2.12, df = 68, 359, P < 0.001) and a significant interaction effect of punches by treatment group (F = 1.35, df = 136, 359, P = 0.015), indicating there is evidence for true differences in the level of HTT mRNA suppression at various anatomical sites depending upon the treatment administered, as expected. To further characterize the relationship between level of HTT mRNA suppression, location in the brain, and treatment group, the punches were categorized according to whether they were within or outside the putamen (the site of the infusion), and a mixed-model ANOVA was performed with membership in groups receiving siRNA for zero (PBS group), 1, or 3 days as the between-monkey factor, and punch category (within or outside the putamen) as a within-monkey factor, with punches nested within punch category. The ANOVA resulted in a significant interaction between punch category and treatment group (F = 14.99, df = 2, 493, P < 0.001). This interaction is portrayed in the graph in Figure 3, which shows no differences among the monkeys receiving PBS or siRNA in HTT mRNA suppression in locations outside the putamen, but a difference among the monkeys receiving PBS or siRNA for differing lengths of time in HTT mRNA suppression in locations within the putamen.

Bottom Line: After a 1-week washout period, monkeys received radiolabeled siRNA targeting huntingtin.After 1 or 3 days of siRNA delivery, monkeys were either terminated, or their pumps were shut off and they were terminated 10 or 24 days later.These findings indicate the rapid onset and durability of siRNA-mediated target gene suppression observed in other organs also occurs in the brain, and support the use of episodic delivery of siRNA into the brain for treatment of Huntington's disease and possibly other neurodegenerative diseases.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, USA.

ABSTRACT
One possible treatment for Huntington's disease involves direct infusion of a small, interfering RNA (siRNA) designed to reduce huntingtin expression into brain tissue from a chronically implanted programmable pump. Here, we studied the suppression of huntingtin mRNA achievable with short infusion times, and investigated how long suppression may persist after infusion ceases. Rhesus monkeys received 3 days of infusion of Magnevist into the putamen to confirm catheter patency and fluid distribution. After a 1-week washout period, monkeys received radiolabeled siRNA targeting huntingtin. After 1 or 3 days of siRNA delivery, monkeys were either terminated, or their pumps were shut off and they were terminated 10 or 24 days later. Results indicate that the onset of huntingtin mRNA suppression in the rhesus putamen occurs rapidly, achieving a plateau throughout the putamen within 4 days. Conversely, loss of huntingtin suppression progresses slowly, persisting an estimated 27-39 days in the putamen and surrounding white matter. These findings indicate the rapid onset and durability of siRNA-mediated target gene suppression observed in other organs also occurs in the brain, and support the use of episodic delivery of siRNA into the brain for treatment of Huntington's disease and possibly other neurodegenerative diseases.

No MeSH data available.


Related in: MedlinePlus