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New Advance Hastens the Production of Neural Cells from Human Pluripotent Stem Cells

Review of “Accelerated Differentiation of Human Pluripotent Stem Cells into Neural Lineages via an Early Intermediate Ectoderm Population” from STEM CELLS by Stuart P. Atkinson

The ectodermal differentiation of human pluripotent stem cells (PSCs) represents the starting point in the generation of neural cells for disease modeling, drug discovery, and regenerative therapies. Unfortunately, the initial stages of traditional differentiation protocols can last for nearly two weeks, thereby severely hampering research aims [1]; however, research has suggested the possibility of significantly shortening this time and hastening the in vitro production of a range of neuronal cells types [2, 3].

In a new advance, researchers led by James R. Dutton (University of Minnesota, Minneapolis, USA) now report the efficient and rapid differentiation of various human PSC lines into a neural precursor population with early intermediate ectodermal characteristics via exposure to bone morphogenic protein (BMP) and fibroblast growth factor (FGF) signaling inhibitors. Furthermore, the Dutton team describes the rapid and flexible differentiation of these rapidly generated precursors into specific neuronal subtypes in response to patterning morphogens. Walsh et al. hope that this advance, described in their recent STEM CELLS study [4], will prompt the development of new and efficient protocols for the generation of PSC‐derived neural cells destined for basic research, drug discovery, and cell therapy applications.

The authors attempted to accelerate the early embryonic fate decisions occurring between pluripotency and ectoderm formation, given its broad applicability to neural differentiation. To do this, the authors aimed to avoid the prolonged passive acquisition of ectodermal fate by disrupting the self-renewal of human PSCs via the inhibition of growth factor-associated pathways [5, 6] (See the STEM CELLS article for more!).

Initial experiments using the immunocytochemical presence of NANOG as a primary readout for disrupted self‐renewal evaluated LDN193189, a highly selective antagonist of BMP receptor isotypes ALK2 and ALK3, in combination with SU5402, vascular endothelial growth factor receptor 2/fibroblast growth factor receptor 1 inhibitor; however, this combination failed to significantly affect pluripotency in various human PSC lines. Interestingly, the replacement of SU5402 with BGJ398, a pan‐FGF receptor inhibitor, prompted vast improvements as evidence by notable alterations to PSC morphology and a significant loss in pluripotency-associated marker expression. Gene expression analysis of PSCs following their treatment with LDN193189 and BGJ398 suggested an immediate loss of pluripotency and the induced formation of an early intermediate ectodermal neural precursor population within 24 hours. Excitingly, this rapidly generated population of precursor cells also quickly responded and flexibly to various morphogens to produce populations of neurons with rostro‐caudal and medial‐lateral neurodevelopmental characteristics.

The authors highlight their findings as a “major advance” in the differentiation of human PSCs into neural cells and anticipate that the relative ease and rapidity of their new protocol will remove a significant bottleneck in this research area and significantly impact the generation of human neurons. The next steps noted in this fascinating new study include exploring the terminal maturation of early intermediate ectodermal neural precursors into electrophysiologically functional neurons.

For more on how this new advance may significantly hasten the production of neural cells from human PSCs, stay tuned to the Stem Cells Portal!

References

  1. Gouti M, Tsakiridis A, Wymeersch FJ, et al., In Vitro Generation of Neuromesodermal Progenitors Reveals Distinct Roles for Wnt Signalling in the Specification of Spinal Cord and Paraxial Mesoderm Identity. PLOS Biology 2014;12:e1001937.
  2. Yoon K and Gaiano N, Notch signaling in the mammalian central nervous system: insights from mouse mutants. Nature Neuroscience 2005;8:709-715.
  3. Mason I, Initiation to end point: the multiple roles of fibroblast growth factors in neural development. Nature Reviews Neuroscience 2007;8:583-596.
  4. Walsh P, Truong V, Nayak S, et al., Accelerated differentiation of human pluripotent stem cells into neural lineages via an early intermediate ectoderm population. STEM CELLS 2020;38:1400-1408.
  5. Chambers SM, Fasano CA, Papapetrou EP, et al., Highly efficient neural conversion of human ES and iPS cells by dual inhibition of SMAD signaling. Nature Biotechnology 2009;27:275-280.
  6. Lippmann ES, Estevez-Silva MC, and Ashton RS, Defined Human Pluripotent Stem Cell Culture Enables Highly Efficient Neuroepithelium Derivation Without Small Molecule Inhibitors. STEM CELLS 2014;32:1032-1042.