Tests in vitro ordinarily ought not to be applied directly to clinical practice. Many proposed therapies pass testing in lab cell cultures but fail or reveal unexpected harms when tested in randomized, controlled clinical trials, the gold standard for drug approvals. Of course, in an emergency, with nothing else available, try anything that makes sense and is reasonably safe.
No, but vitro shows it has an effect, but may be bad for humans....at the point we are at, if someone is very bad off, why not?