News about scandalous stem cell paper retraction from Nature  journal blew up in the mass media  last week. This event reminded me about some other “big stem cell retractions” in the past. I’ve picked five of the most interesting cases in my opinion and to share with you today.
All of them were “big”, scandalous and very sad. I put them in chronological order starting from the most recent one.
1. Harvard stem cell scientist retracts Nature paper
Amy Wagers  asked Nature to retract her paper published earlier this year  about systemic factors rejuvenating the hematopoietic stem cell niche. Many stories came up last week, so you can just read them .
In a statement, Wagers said that she learned information that undermined her confidence in the conclusions and that she immediately notified Joslin, Harvard Medical School, and Nature.
“My primary concern has always been to ensure the integrity of the scientific process and my research, and I have taken all appropriate steps to make certain that any errors in the record are fully corrected,’’ wrote Wagers, a principal faculty member of the Harvard Stem Cell Institute and an associate professor at Harvard Medical School.
Because Nature unveiled duplicated figures from her previous paper, the Blood journal issued a notice of concern. Well, maybe we will get the second retraction soon. Now, as a consequence, all papers from the lab can get questioned !
The reason: Author’s own doubts (in reproducibility?) and figure duplication
follow the updates here 
The journal’s editor-in-chief Graham Parker says he took the radical step on 27 July because two paragraphs in the introduction of the paper, entitled ‘In Vitro Derivation of Human Sperm from Embryonic Stem Cells’, had been plagiarised from a 2007 review published in another journal, Biology of Reproduction.
He had been alerted to the plagiarism on 10 July — three days after the article had been published online — by the editors of Biology of Reproduction. Parker says that the corresponding author, Karim Nayernia of the North East England Stem Cell Institute in Newcastle, UK, and the University of Newcastle, had failed to provide convincing evidence that the two paragraphs had been included in the submitted version of the manuscript by mistake.
Highly recommended to read all comments !
The AGES report says that urologists involved in the study engaged in a series of questionable activities: They designed the trial poorly, inadequately randomized patients, conducted the trial without the appropriate ethics approval, and failed to properly inform trial participants about the nature of the study.
Hannes Strasser , a Medical University of Innsbruck, Austria, urologist and the study’s lead author, is mentioned throughout the AGES report. According to Nature , Medical University of Innsbruck administrators have barred Strasser from seeing patients in the university’s hospital. Strasser has denied any wrongdoing in a letter to the university.
The stem cell treatment involved harvesting muscle cells from 42 female patients’ arms, using those samples to develop autologous myoblasts and fibroblasts, then implanting the stem cells into patients’ urinary sphincters.
Several of the patients treated by Strasser and his colleagues, both as part of the trial and outside the study, have reported severe side effects, including sealing of the urinary sphincter and ruptured bladders, according to Nature.
The reason: poorly designed clinical trial with ethical and regulatory flaws
4. Catherine Verfaillie and elusive MAPC
I wrote about this scandal here :
Other researchers were not able to reproduce this magic and by some reasons New Scientist magazine began investigation of papers and figures about MAPC came up from the group. The magazine’s reporter raised some concerns  according to pictures and methods of MAPC isolation, as described in a few papers. New Scientist called Minnesota University and Nature to solve those issues.
I won’t get into all the details of the findings from this investigation, which forced Verfaillie to correct and clarify some issues, I’ll just tell you the final result – one of the top discoveries in adult stem cell research is fake and was falsified.
The reason: Figure manipulations and falsification, lack of reproducibility
5. Finally the most memorable one – Hwang Woo-Suk case
Well it was definitely the biggest stem cell scandal ever. I don’t need to say much here, just some link to share:
Science: Special Online Collection: Hwang et al. Controversy 
Nature News: Timeline of a controversy 
The reason: research misconduct and fraudulent manipulated data
As you can see there are a lot of different reasons why scientific and clinical papers in stem cell research get retracted. I would just like to emphasize that in such “hot” and competitive field, we will likely see an increased rate of “big retractions”. Any retraction is very sad and has many negative consequences for the authors and for the field. But one of the negative trends in modern academia that we can fix is the following :
Two of the most common complaints heard over coffee in medical science labs and the source of much mental anguish are 1) “Is there any hope in getting a Cell, Science or Nature paper” followed by 2) “Does my career hang in the balance”?
Currently, it seems that the sole determinant of one’s first faculty appointment in medical sciences is publication record. This whets the appetite of the junior science trainee for the coveted article in one of the big three, but such pressure can (more likely than we care to admit) result in some rather unwanted consequences.
PS: All of last week I was exchanging messages with Ivan Oransky  – the author of blog “Retraction Watch ”. He is doing a great job by gathering such useful and important information. I’d recommend you follow his blog or updates on Twitter .