Ultrasmall superparamagnetic nanoparticles targeting E-selectin: synthesis and effects in mice in vitro and in vivo

Figures & data

Figure 1 Negatively stained transmission electron microscopy (TEM) of the ultrasmall superparamagnetic iron oxide (USPIO)–polyethylene glycol (PEG)–Sialyl Lewis X (sLe^x) nanoparticles. The nanoparticles are well separated by the PEG shell.

Figure 2 Dynamic light scattering (DLS) of ultrasmall superparamagnetic iron oxide (USPIO)–polyethylene glycol (PEG) and USPIO-PEG–Sialyl Lewis X (sLe^x).

Figure 3 ζ-potential of ultrasmall superparamagnetic iron oxide (USPIO)–polyethylene glycol (PEG) and USPIO-PEG–Sialyl Lewis X (sLe^x).

Figure 4 Thermogravimetric analysis (TGA) of ultrasmall superparamagnetic iron oxide (USPIO), USPIO–polyethylene glycol (PEG), and USPIO-PEG–Sialyl Lewis X (sLe^x).

Figure 5 Fourier-transform infrared (FTIR) spectra of ultrasmall superparamagnetic iron oxide (USPIO; (black) and USPIO–polyethylene glycol (PEG)–Sialyl Lewis X (sLe^X; red).

Figure 6 Relaxivity (R1 and R2) versus ultrasmall superparamagnetic iron oxide (USPIO)–polyethylene glycol (PEG)–Sialyl Lewis X (sLe^X) concentration.

Table 1 Image parameters and mean optical density (MOD) of primary tumors in footpads in the metastasis group and control group

Parameter	Metastasis group (n=6)	Control group (n=5)	F	P
T2* value, t0 (ms)	22.25±8.08 (13.78 to 30.73)	27.01±9.45 (15.27 to 38.76)	0.814	0.390
T2* value, t1 (ms)	11.57±4.02 (7.35 to 15.78)	24.82±7.84 (15.07 to 34.56)	13.169	0.005
T2* value, t2 (ms)	10.09±4.88 (4.97 to 15.21)	24.15±8.74 (13.30 to 35.00)	11.435	0.008
T2* value, t3 (ms)	12.46±5.63 (6.55 to 18.37)	23.42±7.12 (14.57 to 32.26)	8.149	0.019
ΔT2* value, t1 (ms)	10.69±6.23 (4.15 to 17.23)	3.86±2.20 (−2.60 to 7.00)	6.966	0.027
ΔT2* value, t2 (ms)	12.17±8.67 (3.06 to 21.27)	2.87±1.37 (−0.50 to 6.24)	5.224	0.048
ΔT2* value, t3 (ms)	9.80±3.03 (5.56 to 14.03)	4.32±2.28 (−2.22 to 9.42)	5.563	0.043
Enhancement rate (ER), t1 (%)	45.98±14.03	7.10±5.18	22.393	0.001
ER, t2 (%)	51.15±22.70	11.04±6.01	13.288	0.005
ER, t3 (%)	44.05±13.92	12.09±7.54	12.361	0.007
MOD	0.53±0.24 (0.27 to 0.78)	0.082±0.012 (0.07 to 0.10)	19.850	0.007

Figure 7 Representative images of primary footpad tumor and metastatic inguinal lymph nodes.

Figure 8 T2* value, ΔT2* value and enhancement rate (ER) at different time points in metastasis group and control group.

Figure 9 T2* mapping shows effect of ultrasmall superparamagnetic iron oxide (USPIO)–polyethylene glycol (PEG)–Sialyl Lewis X (sLe^X) contrast agent on images of primary tumors in footpads.

Notes: Color scale used for magnetic resonance imaging (MRI) signal-intensity mapping with software. Top row, T2* mapping of metastasis group at t0, t1, t2, and t3. Bottom row, T2* mapping of control group at t0, t1, t2, and t3. In both mice, USPIO-PEG-sLex was administered via the tail vein.

Figure 10 T2* of primary tumors in footpads in metastasis group and control group before and after intravenous administration of ultrasmall superparamagnetic iron oxide (USPIO)–polyethylene glycol (PEG)–Sialyl Lewis X (sLe^X).

Notes: There was a rapid decrease in mice with metastasis that were given the targeting agent USPIO-PEG-sLe^X. T2* changes in tumors in the control group were relatively gentle. Data points are show mean ± SD.

Figure 11 Results of histological examination of lymph (H&E stain, original magnification 400×) and transplanted tumors (immunohistochemical [IHC], original magnification 400×).

Notes: Top row, metastasis group; bottom row, control group.

Figure 12 Immunohistochemical (IHC) staining in metastasis group and control group. E-selectin preferentially upregulated in metastasis group.

Abbreviation: MOD, mean optical density.

Table 2 Associations between image parameters and mean optical density assessed by Spearman's correlation coefficient

Parameter	Correlation coefficient	P
T2* value, t1	−0.573	0.066
T2* value, t2	−7.00	0.016
T2* value, t3	−4.445	0.170
ΔT2* value, t1	0.655	0.029
ΔT2* value, t2	0.682	0.021
ΔT2* value, t3	0.564	0.071
Enhancement rate (ER), t1	0.718	0.013
ER, t2	0.755	0.007
ER, t3	0.636	0.035

Figure 13 Correlations among image parameters.

Notes: T2* value, ΔT2* value, and enhancement rate (ER) of t1, t2, and t3 and mean optical density (MOD; calculated from immunohistochemistry images by ImageJ). Six parameters (T2* value [t2], ΔT2* value [t1,t2], and ER [t1, t2, and t3]) were related to the MOD. Neither T2* value (t1 and t3) nor ΔT2* value (t3) correlated with MOD. Abbreviation: MOD, mean optical density.