From Rubius Adds $120M to Ready Tests of Red Blood Cells as Drug Carriers:

Erythrocyte, red blood cell
Erythrocyte, red blood cell

Image of red blood cell by Wikimedia user Rogeriopfm
https://commons.wikimedia.org/wiki/File:Erythrocyte_deoxy.jpg
via a Creative Commons license
https://creativecommons.org/licenses/by-sa/3.0/deed.en