Cello is a biomedical company in San Diego, California, founded in 2016. Cello develops biomimetic cell membrane-coated nanoparticles for cancer drug delivery, including chemotherapy agents, immunotherapy agents, or mRNA. Our technology takes advantage of the properties of natural cellular membranes as a stealth coating for nanoparticles. Many animal studies indicated 85-100% of survival rate and long-term immunity for treating various solid tumors with the nanoparticles loaded with immunotherapy agent.