Breaking news Dimitrios Iliopoulos (of miniscule error bars fame) has figured out a way to get cancer stem cells to come back to life!
Anonymous tipster TC reports on two papers, in which Iliopoulos was able to culture cancer stem cells from frozen human breast cancer specimens. Thats nothing special, until you realize that the specimens were purchased from commercial suppliers who snap freeze their samples in liquid nitrogen without any cryopreservative. Here are the papers, and their relevant methods sections
Proc Natl Acad Sci 2011;108;1397-402; PMID21220315
Five human invasive ductal carcinoma tissues (stage III) were purchased from AMS Biotechnology and Biochain Inc.
Cancer Res 2011;71;3196-201; PMID21415163
Three snap-frozen ductal carcinoma tissues were purchased from AMS Biotechnology and Biochain Inc. The purification process of CD44high and CD24highderived from human breast tumors [...] is detailed in the Supplementary Methods.
Supplementary materials Five human invasive ductal carcinoma tissues (stage III) were purchased from AMS Biotechnology and Biochain Inc. The magnetic bead separation is less stressful to the tumor cells in comparison to multiple rounds of cell sorting, thereby allowing the use of these cells in culture experiments.
Results We examined whether metformin selectively inhibits the growth of CSCs from human breast tumors. CSCs (CD44high/CD24low) and NSCCs (CD44low/CD24high) were purified from human mammary adenocarcinomas.
So far so good, until a visit to AMS website brings up the following
Frozen Tissue Blocks and Snap-Frozen Tissue: All fresh frozen tissue samples are collected by certified medical pathologists and are snap-frozen in liquid nitrogen within 30 minutes of surgery excision.
Frozen Tissue Sections: Tissues available include human adult and fetal normal tissues, human diseased and tumor tissues, as well as from mouse, rat, and primates. The tissues are excised, immediately frozen by liquid nitrogen and then stored in -80ºC.
And heres Biochains methodology
The tissues are immediately put in liquid nitrogen after being excised, and then identified by a board-licensed pathologist.
Note that neither supplier mentions anything about cryo-preservatives, and its generally agreed in the field that you need such things (e.g. DMSO) to stand any chance of getting viable cells back from the dead. Further confusing the matter, the Iliopoulos papers reference two other papers, in which cells were cultured from biopsy samples, but in both those papers the samples were freshly collected, not frozen.
With Halloween just around the corner, maybe now is a good time for Iliopoulos to share his secrets on how to get zombie cells out of liquid N2 frozen tissue samples.
[Update] In between preparing this post, and publishing it,TC informs that he/she messaged the NIH and the journals concerned. Then, PNAS actually asked for an explanation from the authors, and based on this the journal responded that they consider the matter closed. Apparently the authors claimed DMSO was used as a cryoprotectant. Also theres the problem that DMSO is useless if the freezing process is too fast. All the samples were snap frozen in liquid N2, so DMSO wont do any good. The rest of the authors explanation makes wild claims about stem cells having special properties that enable them to survive freezing differently to normal cells (how exactly do stem cells resist the physical shearing forces of crystallizing water?). Theres also the inevitable high profile publications from the top experts in the cancer stem cell field have validated ALL our findings claim.
Of course, I emailed the suppliers about whether they used cryo-protectants, and they had this to say
No cryo-preservative agents are added to our snap frozen tissue samples. We just dissect connective tissue, fat and other unwanted material in ice-cold PBS from freshly-resected tissue of interest. Then we snap frozen them in liquid nitrogen.
Any chance Iliopoulos will come forward with his magic pixie-dust zombie stem cell formula? Did the journal really fall for this BS explanation, which is opposite to what the supplier says?