[gus_massa]

It's better the subtitle: "Using the plant like scaffolding, scientists built a mini version of a working heart, which may one day aid in tissue regeneration."

I prefer a modified form: "Using spinach leaf like scaffolding, scientists built a mini version of a working heart"

[dang]

Ok, we'll use that above, shortened to fit the 80 char limit. Thanks!

[gus_massa]

Too late now, but I think "scaffolding" was important, and after reading other comments I think that "working" is an exaggeration.

[dang]

Ok, I tried fixing it anyway.