This document describes an experiment examining the uptake of Feridex, an iron oxide nanoparticle, by macrophages over time and at different concentrations of Feridex. Macrophages were exposed to four concentrations of Feridex mimicking the in vivo ratio and incubated for 20 minutes, 1 hour, 6 hours, and 24 hours. The percentage of macrophages that took up Feridex increased with both higher Feridex concentrations and longer incubation times.

1. SPIO Uptake by Macrophages
Maamoun A.Qamar, MD
Morteza Naghavi, MD

2. The peak iron level in the serum after
administering the recommended dose of
Feridex to humans (i.e. 0.56 mg of Fe/ kg) is:
5.6 µg/ml

3. •To compare it to the ratio of monocytes in
1ml of blood, we would have to consider the
following:
 3-8 % of leukocytes are monocytes
 There are 4000- 10000 leukocytes/ µl of
blood
That means we have 120- 800 monocytes/ µl or
12Χ 104
– 8 Χ 105
/ ml
After injection of Feridex, there will be 1Χ10-4
mmol Fe/ ml

4. In order to simulate the in vivo SPIO-to-
Macrophage ratio, we applied the same ratio
to our ex vivo study.
We used 100 million macrophages in each one
of our 24 tubes used in the study.
We chose 4 concentrations of Feridex that
provided us with a wide range of SPIO-to-
Macrophage Ratio and included the in vivo
ratio too.

5. Protocol:
• We used 8 flasks of CBM macrophages
• After preparing the cells, Feridex was
added with the proper concentration to
each labeled tube
• Incubation was at 37° C
• For each time point, we centrifuged the
tubes at 1000 rpm’s for 5 min
• Washed with 1X PBS for 5 min
• Resuspended in 2% paraformaldehyde to
fix the cells

6. time concentration
20
Min
1
Hour
6
Hours
24
Hours
50µl 100µl 250µl 500µl control control

9. Macrophage Uptake of Feridex
After 20 Min
0
10
20
30
40
50
60
70
80
90
50 100 250 500 control control
20 min
Feridex (µL)

10. Macrophage Uptake of Feridex
After 60 Min
0
10
20
30
40
50
60
70
80
90
50 100 250 500 control control
60 min
Feridex (µL)

11. Macrophage Uptake of Feridex
After 6 Hours
0
10
20
30
40
50
60
70
80
90
50 100 250 500 control control
6 Hours
Feridex (µL)

12. Macrophage Uptake of Feridex
After 24 Hours
0
10
20
30
40
50
60
70
80
90
50 100 250 500 control control
24 Hours
Feridex (µL)

13. Macrophage uptake of Feridex
increases with increasing the
Amount of Feridex
0
10
20
30
40
50
60
70
80
90
50 250 control
20 min
60 min
6 hours
24 hours

14. Macrophage Uptake of Feridex
Increases With Time
0
10
20
30
40
50
60
70
80
90
20 Min 60 Min 6 Hours 24 Hours
50
100
250
500
control
control