Dirks showed that some of the immature-looking cells from his patients could form tumorlike clumps in the test tube, unlike most other cells from the tumors, but he didn't have a method to pluck out the stem cells.
Whatever you think of the man's style, you've got to admire his pluck. (McQueen's, I mean.) As for Heller, you can't gainsay his knowledge of the subject.