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2 thoughts on “Of non-existent black holes and pickled stem cells”

  1. Indeed Haruko Obokata and Charles Vacanti’s team data look amazing and even intriguing.
    However one can wonder about the true mechanism of cell reprogramation that they report.
    A decrease in extracellular pH does not affect so much intracellular pH and even less intranuclear pH. let’s recall that a cell has a lot of defense to withstand acidosis or alcalosis : a Na/H antiport a Na-dependent and a Na-independent Cl/HCO3 as well as intracellular proteins that buffers H+. a Ca2+/H+ mitochondrial exchanger. The nucleus has a K+/H+ exchanger pretty efficient to regulate intranuclear pH as well as chromatin that buffers a lot H+ . The reader of that paper would have like (love) to see in this paper which intranuclear pH is required to repress in a specific manner somatic genes and turn on embryonic genes in a similar specific manner. Can H+ feature such a specific effect on gene repression and transcrition?
    How sure are the authors that their CD45+ faxed cells do not include some stem cells? Why doe it not work on adult somatic cell?
    Can they reprogram a single clonal cell? This is what one can expect looking at the very high efficiency of their reprogramation protocol.
    What was the virus load (maybe even acidifying the host cells) imposed to the cells when cells were reprogrammed with retroviral vectors and Yamanaka factors? a cell stress?
    Let’s first see how many labs can reprogram somatic cells using their protocol
    Any data specifically in the stem cell field needs to be challenged. The hope of patients about regenerative medecine is so high that scientists have to be very cautious before releasing scientific data in the news

    1. Thanks for sharing your thoughts Michel. It is appreciated. You are right from cell physiology perspective. I think the emerging stem cells energetics area could tackle these questions.

      We too discussed similar questions as yours. It could be that the pluripotency pathways may be induced even with a subtle change in extracellular pH without altering the cytoplasmic homeostasis itself. And we know that the stem cell milieu/niche have greater impact on the cell state by acting via receptors.

      Obviously, there will always be challenges about reproducibility of any data published. And we will know in couple of years if not more, how this method is. My motive for writing about these articles is primarily to highlight the need of creative thinking in Science.

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