1. In Vitro Evaluations of TNF-a Gene Silencing in Macrophages using Hyaluronic Acid-Based Self-Assembled
Nanoparticles for Anti-Inflammatory Therapy
Kamaljeet Singh Sandhu, Arun K. Iyer, Qiong L. Zhou, and Mansoor Amiji
Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University,
Boston, MA 02115 (Email: sandhu.k@husky.neu.edu)
Objective
Methods Results
Conclusions
References
HA/PEI conjugates were synthesized and characterized by 1H-
NMR .
TNF-α silencing HA/PEI siRNA Nanoparticles: 3mg/ml of
HA/PEI was taken in PBS and added to 0.5mg/ml of TNF-
silencing siRNA. Then the mixture was vortexed for
approximately 1 minute. Mixture was then kept for about 20
minute and then stored in refrigerator at 4⁰C until further used.
The formulations were characterized for size, surface charge
with zeta sizer and transmission electron microscopy (TEM).
RNA loading efficiency was examined with RiboGreen® RNA
assay.
Gel electrophoresis was used to check the stability of RNA
under treatment of 2% poly(acrylic acid).
Intracellular delivery and TNF-a gene silencing efficacy was
evaluated in J774.A1 adherent murine macrophages that were
stimulated with lipopolysaccharide (LPS). RT-PCR and ELISA
were used for qualitative and quantitative determinations of
TNF-a levels post-administration of siRNA.
.
Diabetes is a global problem and one with the highest
healthcare expenditure. Over 230,000 deaths were recorded in
2007 alone due to this disease.
Diabetes mellitus (or type 1 diabetes) is a group of metabolic
diseases in which the body loses its ability to either produce or
use insulin, resulting in higher blood glucose levels which can
gradually lead to life threatening long term complications such
as myocardial infarction, cerebrovascular stroke, retinopathy,
neuropathy, nephropathy, end stage renal diseases, periodontal
pathologies, etc.
Current treatment strategies include administration of insulin
pills, oral hypoglycaemics and intensive insulin therapy.
Moreover transplantation of pancreas or just islet cells of
langerhans have been tested for treatment of type-1 diabetes,
but safety concerns have limited the success of these
strategies.
Increased levels of TNF-α, a pro-inflammatory cytokine, has
been implicated in patients with diabetes. Thus, strategies
targeting down-regulation of TNF- α can be beneficial in the
treatment of diabetes.
RNA interference therapy has emerged as a powerful strategy
to down-regulate TNF-α. However, intracellular delivery of small
interfering RNA is a major challenge as the nucleic acid
payload must navigate through the circulatory system of body
and avoid filtration by kidney, aggregation with serum proteins,
uptake by phagocytes and degradation by endogenous
nucleases enzymes. These physiological parameters must be
overcome by a delivery system for efficient use of siRNA as a
clinically viable therapeutic strategy for diabetic patients
Introduction
Formulation Diameter (nm) Polydispersity
Index
Zeta Potential
(mV)
1 HA-PEI TNFα siRNA
NP in PBS
91.97 ± 3.02 0.206 -10.8 ± 2.54
2 HA-PEI TNFα siRNA
NP in water
164.4 ± 6.74 0.342 -12.7 ± 3.02
3 HA-PEI Scr siRNA NP
in PBS
105.87 ± 5.98 0.216 -15.1 ± 3.27
Figure 5b: Semi-quantitative analysis of gel electrophoresis bands
These epifluorescence images confirm internalization of Cy3
labeled TNF-α siRNA by the cells. For this study nanoparticles
were formulated using cy3 labeled TNF-α siRNA and FITC
labeled HA-PEI to perform epifluorescence microscopic analysis
of cell uptake. Images Internalization was best seen after12
hours of incubation.
RT-PCR analysis data of TNF-α gene silencing after treatment
with siRNA duplexes complexed with Lipofectin®, or in HA-PEI
nanoparticles (a) and semi-quantitative analysis of expression
profile (b).
Figure 3. Transmission electron microscopy images siRNA
encapsulated in HA-PEI self assembled nanoparticles.
No
Treatment
Scrambled
nanopartcle
s
50 nM
HA/PEI
nanoparticles
75 nM
HA/PEI
nanoparticle
s
100 nM
HA/PEI
nanoparticle
s
Lipofectin
-50 nm
siRNA
Lipofectin-
75 nm
siRNA
Lipofectin-
100 nm
siRNA
The pro-inflammatory cytokine TNF-α gene silencing was
evaluated using a non-viral hyaluronic acid-poly(ethylene imine
(HA-PEI) conjugates in macrophages for potential therapeutic
approach in the treatment of diabetes-associated inflammation.
Figure 1. Mechanism of RNA intereference1.
Results
Table 1: Characterization of Nanoparticle formulation
Particle Size and Zeta Potential - TNF-α containing HA-PEI
nanoparticles were characterized by dynamic light scattering
(DLS), using the Malvern Zetasizer. Nanoparticles showed
unimodal distribution with a mean particle diameter of ~90nm
and zeta potential of -12mV and were stable at that size when
stored at 4ºC. These results are summarized in Table 1.
Lane 1: Ladder
Lane 2: No Treatment
Lane 3: Scramble Nanoparticles
Lane 4: 50 nM HA/PEI Nanoparticles
Lane 5: 75 nM HA/PEI Nanoparticles
Lane 6: 100 nm HA/PEI Nanoparticles
Lane 7: Lipofectin-50 nm siRNA
Lane 8: Lipofectin-75 nm siRNA
Lane 9: Lipofectin-100 nm siRNA
Lane 10: Ladder
Figure 5a. RT-PCR analysis- 24 hr study
Figure 2. Self assembled HA-PEI/siRNA nanoparticles. Figure illustrating
core-shell structure of Cy3-labeled siRNA conjugated to PEI modified HA
(with FITC) (a) and 1H-NMR of HA-PEI-FITC conjugate (b).
a
Free NH2
(Peak
from PEI) (Peaks
from PEI)
Peak from
FITC
Peaks from
HA
Solvent peak
(D2O)
b
PEI modified HA (with
FITC label)
HA-PEI/siRNA (nanoparticle)
Size of nanoparticle:
~ 80 to 100 nm (by Dynamic
Light Scattering analysis)
 The preliminary results show that siRNA can be encapsulated in self-assembled HA-PEI nanoparticles and these can be efficiently
delivered to silence TNF-α gene with potential to treat diabetes-related inflammation.
 Studies showed that biological activity of siRNA was preserved while formulating the nanoparticles. TEM imaging confirmed the
core-shell structure of the nanoparticles with the nucleic acid confined to the center.
 These nanoparticles are efficiently taken up by J774.A1 adherent murine macrophage cells.
 Also these HA-PEI nanoparticles are capable of efficiently silencing TNF-α expression in these cells as confirmed by RT-PCR and
ELISA.
 Kim, D.H. and J.J. Rossi, Strategies for silencing human disease using RNA interference. Nature Reviews Genetics, 2007. 8(3):
p. 173-84.
 Elbashir, S.M., et al., Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells. Nature, 2001.
411(6836): p. 494-8.
 Whitehead, K.A., R. Langer, and D.G. Anderson, Knocking down barriers: advances in siRNA delivery. Nat Rev Drug Discov,
2009. 8(2): p. 129-38.
Figure 6. ELISA data of TNF-α silencing after treatment with
siRNA duplexes complexed with Lipofectin®, or in HA-PEI
nanoparticles . Asterisk indicates statistical significance relative to
the untreated as well as the scrambled siRNA treatment groups
(p < 0.05).
Figure 4. DIC and fluorescence microscopy images of siRNA-
encapsulated HA-PEI nanoparticles in J774.A1 cells
The adherent murine macrophages J774.A1 cells were stimulated
with lipopolysaccharide (LPS) for 6 hours prior to dosing with
native and scrambled (as control) siRNA sequences. The siRNA
dose ranged from 50 to 100 nM. HA-PEI nanoparticles were
effective in TNF-α gene and protein silencing similar to the levels
obtained with Lipofectin®-complexed siRNA . HA-PEI, on the other
hand, was shown significantly less toxic that Lipofectin® in
intracellular siRNA delivery.
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