Monster tumors could offer new glimpse at human development

Finding just the right model to study human development – from the early embryonic stage onward – has been a challenge for scientists over the last decade. Now, bioengineers at the University of California San Diego have homed in on an unusual candidate: teratomas.

Teratomas – which mean "monstrous tumors" in Greek – are tumors made up of different tissues such as bone, brain, hair and muscle. They form when a mass of stem cells differentiates uncontrollably, forming all types of tissues found in the body. Teratomas are generally considered an undesired byproduct of stem cell research, but UC San Diego researchers found an opportunity to study them as a model for human development.

"We've been fascinated with the teratoma for quite a while," said Prashant Mali, a professor of bioengineering at the UC San Diego Jacobs School of Engineering. "Not only is the teratoma an intriguing tumor to look at in terms of the diversity of cell types, but it also has regions of organized tissue-like structures. This prompted us to explore its utility in both cell science and cell engineering contexts."

"There's no other model like it. In just one tumor, you can study all of these different lineages, all of these different organs, at the same time," said Daniella McDonald, an M.D/Ph.D. candidate in Mali's lab and co-first author of the study. "Plus, it's a vascularized model, it has a three-dimensional structure and it's human-specific tissue, making it the ideal model for recreating the context in which human development happens."