http://blogs.nature.com/news/2014/09/stap-co-author-offers-yet-another-recipe-for-stem-cells.html

关于STAP细胞的话题，本来已经没有什么值得再报道的。但是小保方美国哈佛大学的导师再生医学专家Charles Vacanti不甘寂寞，竟然再次启动这一话题，说自己有培养STAP细胞的秘密武器，制造STAP细胞并不是单纯用酸性培养基或机械压迫，还需要另外一个条件，就是要ATP 的参与，ATP就是三膦酸腺苷。不过他认为是由于严重疏忽导致这一错误信息，其实这种说法并不那么可信。细胞培养液的成分是细胞培养中关键问题，尤其是这种用于诱导干细胞的酸性培养基。其成分尤其不可能忽视。ATP浓度如果高于普通培养基，竟然因为疏忽绝对不可能。

CharlesVacanti教授也太让科学家失望了，明明知道过去提供的方法不可靠，怎么能拿出来让大家用？而将自己的秘方藏起来，看这样子，似乎小保方都不一定知道这个秘密。

“In recent months, our lab decided tore-explore the utility of a low pH solution containing ATP in generating STAPcells,” Vacanti writes in the revised protocol. “We found that while pH aloneresulted in the generation of STAP cells, the use of a low pH solutioncontaining ATP, dramatically increased the efficacy of this conversion.  When this acidic ATP solution was used incombination with mechanical trituration of mature cells, the results were evenmore profound” (emphasis original).

意思是用比较温和的酸性培养结合ATP，能明显提高转化效率，如果再结合机械压迫，那么转化效果更理想。

ATP这个东西名气确实大，在细胞内的作用也十分重要，因为这是细胞能量的货币，没有ATP，细胞就无法正常运行。不过这个ATP主要在细胞内发挥作用，如果离开细胞到细胞外，则变成一种类似激素或细胞因子的物质，而且许多细胞表面上存在能结合ATP的受体，这种效应确实能导致细胞发生炎症样效应。如果结合ATP才可以出现这一诱导效应，从逻辑上也没有不可以的道理。不过这些学者从什么角度考虑到用ATP作为协同效应分子？不可能从能量角度，因为细胞外ATP不可能产生这种效应。除非从整体组织损伤角度，因为只要细胞坏死或损伤，就有可能出现细胞外ATP增加的情况。要知道细胞内外这一物质浓度差别达到1000倍。不过其他情况也有许多，例如钾和钙离子浓度。为什么没有考虑用这两种离子作为刺激因子？

现在我们不能知道，这个所谓的秘密配方是否能成为制造出STAP细胞的法宝。但是，这种故意隐藏科研细节的行为是否妥当？

人们在发表论文的时候，故意将其中关键步骤避而不谈，主要是为避免其他学者超越，这好像成为学术领域的一个潜规则，但这种做法显然对促进学术的发展没有好处。一是验证他人研究存在风险，因为不能依靠公开发表论文中提供的研究方案，因此学术上一直有一种说法：重复有风险，开展要慎重。另外一个是确定研究的真实性存在困难，这在某种程度上已经成为制约科学发展的一种毒瘤，在实用技术上，受商业利润的影响，这种现象尤其普遍。但是在基础理论研究上，如果也采用同样的技术壁垒，将受到学术界的唾弃，学术研究本质上不提倡保密，提倡公开交流，因为理论上任何学术思想和技术都是在前人基础上的发展。假如STAP细胞确实是因为需要ATP才能成功，那么国际上许多先后重复小保方论文而又无法重复的学者会怎么想，会不会接受这个Charles Vacanti的行为？当然，如果这个方法确实被证明可行，会怎么样？

这有点类似武侠小说中的情节，某人受到某一毒伤，必须用某人提供的特殊解药，没有这个解药就无法治疗，而这个解药或许就是最普通的一种东西，但别人不了解，竟然成为某些人头脑中的秘密，用于制约他人。在功利性的影响下，今天的科学研究竟然堕落到如此地步，从这一案例中可见一斑。

ATP名称为腺嘌呤核苷三磷酸，又叫三磷酸腺苷，其中A表示腺苷，T表示其数量为三个，P表示磷酸基团，即一个腺苷上连接三个磷酸基团。其结构简式是：A—P～P～P，其相邻的两个磷酸基之间的化学键非常活跃，水解时可释放大量能量，因此称为高能磷酸键，用“~”表示。在细胞的生命活动中，ATP远离A的一个高能磷酸键易断裂，释放出一个磷酸和能量后成为腺苷二磷酸（ADP）。在有机物氧化分解或光合作用过程中，ADP可获取能量，与磷酸结合形成ATP。

Asenior co-author on controversial, and now retracted, stem cell papers has quietlyposted new tips on how the research can be replicated.

Twopapers claiming that stressing the body’s cell could produce embryonic-likestem cells, a process called stimulus triggered acquisition of pluripotency(STAP), were heralded when published in Nature in January but thrashed soonafter when problematic images and figures were soon found.

Thatmight not have been so worrisome if the experiments, which the authors calledeasy to do, were replicated, but various external groups tried and failed to doso. Co-authors in Japan responded with a tipsheet. Soon after that, the leadauthor on the paper laying out the fundamental STAP technology, Charles Vacantiof the Brigham and Women’s Hospital in Boston, Massachusetts, released his own,quite different, list of tips for reproducing STAP. Still no one succeeded inreplicating the findings.

SinceApril, Hitoshi Niwa, a well-respected mouse stem cell specialist at the Centerfor Developmental Biology (CDB) in Kobe and a co-author on the papers, has beengiving a focused, last-ditch effort to replicate the experiment; on August 27,he reported no luck so far and suggested that light emission from dying cells,known as autofluorescence, might have been confused with fluorescent tags meantto signal conversion to the embryonic-like state.

Duringthat period, the lead author on both papers, the CDB’s Haruko Obokata, wasfound guilty of misconduct and both papers were retracted. Obokata’s supervisorat the CDB, Yoshiki Sasai, committed suicide, and Vacanti stepped down aschairman of Brigham and Women’s Department of Anesthesiology, Preoperative andPain Medicine. The CDB itself has halved in size.

Onemight have thought that STAP was finished. But Vacanti is not one to give up soeasily.

Evenwhen he finally agreed to retract the papers, he maintained, in a post on hisdepartment’s website, that “there has been no information that cast doubt onthe existence of the stimulus-triggered acquisition of pluripotency (STAP) cellphenomenon itself.” Vacanti said that he was confident that Niwa would“replicate the core STAP cell concept that my brother Martin and I originallyhypothesized, and trust that it will be verified by the RIKEN as well asindependently by others.”

Now,in a note posted without fanfare on Vacanti’s department’s website and datedSeptember 3 — one week after Niwa announced failure to replicate the findings —Vacanti has offered his second revision to the STAP protocol.

Incomparison his first revised protocol in March (“Refined protocol for generatingSTAP cells from mature somatic cells”), the new one (“REVISED STAP CELLPROTOCOL. 09.03.14:”) highlights the use of ATP in the solution, in combinationwith two stresses — exposure to acid and physical pressure on the cellmembranes — that he used in the previous recipe. “In recent months, our labdecided to re-explore the utility of a low pH solution containing ATP ingenerating STAP cells,” Vacanti writes in the revised protocol. “We found thatwhile pH alone resulted in the generation of STAP cells, the use of a low pHsolution containing ATP, dramatically increased the efficacy of thisconversion.  When this acidic ATPsolution was used in combination with mechanical trituration of mature cells,the results were even more profound” (emphasis original).

 “We made a significant mistake in ouroriginal declaration that the protocol was ‘easy’ to repeat,” the protocolcontinues. “This was our belief at the time, but it turned out to be incorrect.Many of the steps described appear to be a function of the technique of theindividual investigator. Consequently, the revised protocol below shouldincrease the likelihood of success.”

相关专题：小保方事件追踪
转载本文请联系原作者获取授权，同时请注明本文来自孙学军科学网博客。
链接地址：https://blog.sciencenet.cn/blog-41174-827615.html

上一篇：氢气对NLRP3的作用
下一篇：人工脾面世或有助于克服血液感染