Assertion: adult stem cell | /r/HasProperty | difficult culture
Facets:
value: often
type: TEMPORAL
value: in vitro
type: LOCATION
Source sentences:
text: They are difficult culture in-vitro , impossible for some cell types, and t hey are fairly difficult to get using other methods bec a use
text: This would allow the cells to be easily manipulated, although they are often relatively rare and difficult to grow in culture.