Histopathology

Heart, kidney, lymph node, lungs, liver, and injection sites from the sacrificed mice were collected and fixed in 10% formalin for 48 h. The organs were further processed and embedded in paraffin, and 8-μm sections were cut using the Leica RM 2245 Rotary Microtome. The sections were then stained using the following hematoxylin–eosin staining procedure. Sections were first dewaxed in xylene (three changes of 2 min each) and then rehydrated in absolute alcohol (two changes of 2 min each), in 90% for 2 min, in 70% for 2 min, then washed in running tap water for 2 min and stained in hematoxylin for 3 min, and again washed in running tap water for 2 min. Sections were then washed in 70% alcohol for 2 min and stained in eosin for 3 min. Sections were then washed in 95% alcohol for 2 min and then in absolute alcohol (three changes of 2 min each). Finally, the sections were rapidly dehydrated and fixed in xylene (three changes of 2 min each) and mounted in DePeX. The sections were then observed under the Zeiss LSM 510 META confocal microscope at 20× magnification.