Increased brain radioactivity by intranasal ³²P-labeled siRNA dendriplexes within in situ-forming mucoadhesive gels

Figures & data

Table 1 Samples, dosage, routes and number of doses used in the different experimental groups

Experimental group	Formulation	Route of administration	Number of dosesa	Timeb (minutes)
siRNA/G7	Buffer	Intravenous	1	90
siRNA/G7	Buffer	Intranasal	1	90
siRNA/G7	Buffer	Intranasal	2	180
siRNA/Lipofectamine™ 2000	Buffer	Intranasal	2	180
siRNA/G7	PxCBP	Intranasal	1	90
siRNA/G7	PxCBP	Intranasal	2	180
siRNA/Lipofectamine 2000	PxCBP	Intranasal	2	180
Naked siRNA	PxCBP	Intranasal	2	180

Notes:

a The two doses were administered with a 90-minute interval;

b time between first administration and sacrifice.

Abbreviations: siRNA, small interfering RNA; G7, generation 7 dendrimers; PxCBP, poloxamer/carbopol gel.

Figure 1 Variations of the elastic modulus, G′, as a function of temperature for the in situ-forming gels with or without dendriplexes.

Abbreviations: PxCBP, poloxamer/carbopol gel; PxChi, poloxamer/chitosan gel.

Table 2 Parameters obtained from flow curves modeled using the Oswald-de-Waele equation (power law) of in situ-forming gels at 10°C and 25°C

Sample	Temperature (°C)	Flow index (n)	Consistency index (k: Pa.s^n)	R^2
PxCBP	10	0.929	0.25	0.99
PxCBP/dendriplex	10	0.901	0.24	0.99
PxChi	10	0.201	55	0.98
PxChi/dendriplex	10	0.373	10	0.97
PxCBP	25	0.063	318	0.99
PxCBP/dendriplex	25	0.043	209	0.92
PxChi	25	0.059	351	0.70
PxChi/dendriplex	25	0.074	263	0.63

Abbreviations: PxCBP, poloxamer/carbopol gel; PxChi, poloxamer/chitosan gel.

Figure 2 Flow curves (shear stress as function of shear rate) of in situ-forming gels with or without dendriplexes at (A) 10°C and (B) 25°C.

Note: “Mod” indicates experimental data fitted to the Oswald–de Waele equation.

Abbreviations: siRNA, short interference RNA; PxCBP, poloxamer/carbopol gel; PxChi, poloxamer/chitosan gel.

Figure 3 Elastic (G′) and viscous (G″) modulus as a function of angular frequency of in situ-forming gels with or without dendriplexes at (A) 10°C and (B) 25°C.

Abbreviations: PxCBP, poloxamer/carbopol gel; PxChi, poloxamer/chitosan gel.

Figure 4 Release profile of radioactivity from in situ-forming (A) poloxamer/carbopol and (B) poloxamer/chitosan gels as function of time.

Abbreviations: PxCBP, poloxamer/carbopol gel; PxChi, poloxamer/chitosan gel; siRNA, short interference RNA; ATP, adenosine 5″-triphosphate.

Table 3 Histopathological evaluation of nasal mucosa after treatments

	Buffer	Dendriplex in buffer	Dendriplex within PxCBP gel	SDS
Epithelial eosinophilia	0	0	0	0
Leukocytic margination	0	0	0	+
Luminal exudate	++	+	++	+++
Desquamated epithelial cells	0	0	0	+
Hyperemia	+	0	+	++
Osteoblast activation	0	0	0	+

Notes: The microscopic findings were graded between 0 and 3 (0 = absent, + = minimal, ++ = moderate, +++ = severe histological change).

Abbreviations: PxCBP, poloxamer/carbopol gel; SDS, sodium dodecyl sulfate.

Figure 5 Histopathology of rat nasal tissues after three intranasal doses of (A–C) dendriplexes in buffer or (D–F) dendriplexes within in situ-forming poloxamer/carbopol gel. (A and D) magnification ×40, (B and E) magnification ×100, (C and F) magnification ×400 (respiratory epithelium). Arrows showed luminal exudates (A and E) and normal lymphatic infiltration (E).

Figure 6 Scintillation measurement of radioactivity in (A) blood and (B) brain after one or two intravenous or intranasal doses of dendriplexes in rats (n = 3).

Notes: *P < 0.05; **P < 0.01 (statistically significant difference).

Abbreviations: IV, intravenous; DX, dendriplex; LX, lipoplex; siRNA, short interference RNA PxCBP, poloxamer/carbopol gel.

Figure 7 (A) Brain/blood radioactivity ratio and (B) brain distribution of radioactivity following one or two intravenous or intranasal doses of dendriplexes in rats.

Note: *P < 0.05 (statistically significant difference).

Abbreviations: IV, intravenous; DX, dendriplex; LX, lipoplex; siRNA, short interference RNA; PxCBP, poloxamer/carbopol gel.