Xenogeneic Transplantation Promoted Human Exosome Sequestration in Rat Specific Organs

Here, we aimed to study the distribution pattern of normal and cancer xenogeneic exosomes (Exos) and possible interspecies reactions in a rat model.

Exos were isolated from normal Human umbilical vein endothelial cells (HUVECs) and MDA-MB-231 breast cancer cells. Diameter size and zeta potential distribution were studied using dynamic light scattering (DLS). The morphology of isolated Exos was monitored by scanning electron microscopy (SEM) images. Using western blotting, protein levels of exosomal tetraspanins were detected. For the in vivo study, Dil-labeled normal and cancer Exos were injected into the tail vein (100 µg exosomal protein/rat) three times at 1-hour intervals. After 24 hours, rats were euthanized and the cellular uptake of Exos was monitored in different organs using immunofluorescence staining (IF).

The size distribution and mean zeta potential of HUVEC and MDA-MB-231 cells Exos were 80±29.94 and 64.77±25.49 nm, and -7.58 and -11.8 mV, respectively. Western blotting revealed CD9, CD81, and CD63 in normal and cancer Exos. The SEM images exhibited typical nano-sized round-shape Exo particles. IF staining indicated sequestration of administrated Exos in splenic tissue and lungs. The distribution of Exo in kidneys, aorta, and hepatic tissue was less. These features were more evident in the group that received cancer Exos. We found no obvious adverse effects in rats that received normal or cancer Exos.

Normal and cancerous xenogeneic human Exos can be sequestrated prominently in splenic tissue and lungs. Novel delivery approaches and engineering tools are helpful in the target delivery of administrated Exos to the injured sites.