A Primitive Growth Factor, NME7AB, Is Sufficient to Induce Stable Naïve State Human Pluripotency; Reprogramming in This Novel Growth Factor Confers Superior Differentiation

Abstract

Scientists have generated human stem cells that in some respects mimic mouse na€ ıve cells, but their dependence on the addition of several extrinsic agents, and their propensity to develop abnormal karyotype calls into question their resemblance to a naturally occurring "na€ ıve" state in humans. Here, we report that a recombinant, truncated human NME7, referred to as NME7 AB here, induces a stable na€ ıve-like state in human embryonic stem cells and induced pluripotent stem cells without the use of inhibitors, transgenes, leukemia inhibitory factor (LIF), fibroblast growth factor 2 (FGF2), feeder cells, or their conditioned media. Evidence of a na€ ıve state includes reactivation of the second X chromosome in female source cells, increased expression of na€ ıve markers and decreased expression of primed state markers, ability to be clonally expanded and increased differentiation potential. RNA-seq analysis shows vast differences between the parent FGF2 grown, primed state cells, and NME7 AB converted cells, but similarities to altered gene expression patterns reported by others generating na€ ıve-like stem cells via the use of biochemical inhibitors. Experiments presented here, in combination with our previous work, suggest a mechanistic model of how human stem cells regulate self-replication: an early na€ ıve state driven by NME7, which cannot itself limit self-replication and a later na€ ıve state regulated by NME1, which limits self-replication when its multimerization state shifts from the active dimer to the inactive hexamer. STEM CELLS 2016;34:847-859 SIGNIFICANCE STATEMENTThe results of these studies argue that a na€ ıve stem cell state does exist in humans and indicates that a naturally occurring growth factor, NME7, supports the earliest na€ ıve state, but is replaced by a related growth factor, NME1, that limits pluripotent growth via changes in its multimerization state. The existence of a na€ ıve state in humans could have a profound effect on the study of basic science and on future stem cell therapies. Na€ ıve stem cells, if they live up to their promise, could streamline low cost, high throughput stem cell production, improve the quality of stem cell derived cells and render genetic editing routine.

Energy Metabolism Regulates Stem Cell Pluripotency

“…This study indicated that MTCH2 is important for elongated mitochondria which itself was sufficient for driving naïve-toprimed interconversion by altering histone deacetylation and nuclear gene reprogramming (Bahat et al, 2018). In addition, recent work has demonstrated that supplementation with a recombinant truncated human NME7 (NME7 AB ) is sufficient to induce a stable naïve-like state in hPSCs (Carter et al, 2016) associated with reactivation of mitochondrial function and stimulation of ATP production (O'Reilly et al, 2019).…”

Extracellular NME proteins: a player or a bystander?

“…Smagghe et al 19 demonstrated through surface plasmon resonance that differential NME interaction with the extracellular domain of MUC1* is strictly dependent on the NME multimerization state. The updated mechanistic model 20 (Figure 1) suggests that early stem cells are able to secrete monomer NME7 that can bind to the extracellular domain of MUC1* and promotes growth and pluripotency. Hence, extracellular NME7 has an important role in maintenance of early stem cell in the naïve status.…”

“…Mechanistic model illustrating how NME7 and NME1 control pluripotency and differentiation in stem cells. Modified from Carter et al20 …”

Capturing Human Naïve Pluripotency in the Embryo and in the Dish

“…Several groups have developed various culture systems to revert EpiSC-like conventional human PSCs [41,48,107,119,[175][176][177][178][179][180][181][182][183] or derive de novo hESCs [41,107,178,184] to pluripotent states resembling the human preimplantation epiblast (Fig. 3).…”