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Simple and Efficient Protocol Developed to Produce hPSC-Derived Corneal Cells

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Review of “Differences in the Activity of Endogenous Bone Morphogenetic Protein Signaling Impact on the Ability of Induced Pluripotent Stem Cells to Differentiate to Corneal Epithelial-Like Cells” from STEM CELLS by Stuart P. Atkinson

The loss of limbal stem cells (LSCs) from the cornea leads to deficiencies in the transparent corneal epithelial layer and subsequent visual impairment [1]. Transplantation of ex vivo-expanded autologous LSCs or oral mucosa epithelial cells has proven a successful treatment in some patients; however, the application of corneal epithelial cells differentiated from human pluripotent stem cells (hPSCs) may represent a more effective approach.

A new STEM CELLS study from Majlinda Lako (Newcastle University, UK) now reports on the development of a simple and defined feeder-free monolayer hPSC differentiation strategy for the generation of corneal epithelial progenitors and mature corneal epithelial cells. Of note, during the development of this exciting new protocol, the authors highlight the significant influence of endogenous bone morphogenetic protein (BMP) signaling pathway activity in hPSCs on differentiation efficiency [2]. 

So what were the details of this new study by Kamarudin et al., which employed one human embryonic stem cell line (hESC) and two human induced pluripotent stem cell (hiPSC) lines?

  • Step one of the protocol differentiated hPSCs seeded on Matrigel plates into corneal epithelial progenitors by exposure to bone morphogenetic protein 4 (BMP4), all trans-retinoic acid (ATRA), and epidermal growth factor (EGF) for 9 days
    • These three factors promote non-neural ectodermal commitment and the proliferation of corneal epithelial progenitors
  • Step two employed collagen-IV-coated cell culture plates and corneal-specific-epithelial cell media (CnT-Prime medium) for an additional 11 days to promote the emergence of mature corneal epithelial cells
    • Collagen-IV mimics the LSC niche [3, 4]
    • CnT-Prime medium maintains the ex vivo expansion of human corneal epithelial progenitors [5]
  • Interestingly, the authors noted variances in the differentiation efficiency of the hPSCs employed
    • Differentiation efficiency correlated to levels of endogenous BMP signaling
    • However, activation of BMP signaling via the application of SB431542, a specific transforming growth factor β inhibitor, improved differentiation efficiency

The authors now hope to test engraftment and functionality of their hPSC-derived corneal cells in animal models of LSC loss to truly demonstrate the great potential of this simple and efficient differentiation protocol.

To hear about all the future studies and more on LSCs, stay tuned to the Stem Cells Portal.

References

  1. Dua HS, Saini JS, Azuara-Blanco A, et al., Limbal stem cell deficiency: concept, aetiology, clinical presentation, diagnosis and management. Indian J Ophthalmol 2000;48:83-92.
  2. Kamarudin TA, Bojic S, Collin J, et al., Differences in the Activity of Endogenous Bone Morphogenetic Protein Signaling Impact on the Ability of Induced Pluripotent Stem Cells to Differentiate to Corneal Epithelial-Like Cells. STEM CELLS 2018;36:337-348.
  3. Schlotzer-Schrehardt U, Dietrich T, Saito K, et al., Characterization of extracellular matrix components in the limbal epithelial stem cell compartment. Exp Eye Res 2007;85:845-60.
  4. Blazejewska EA, Schlotzer-Schrehardt U, Zenkel M, et al., Corneal limbal microenvironment can induce transdifferentiation of hair follicle stem cells into corneal epithelial-like cells. Stem Cells 2009;27:642-52.
  5. Gonzalez S, Chen L, and Deng SX, Comparative Study of Xenobiotic-Free Media for the Cultivation of Human Limbal Epithelial Stem/Progenitor Cells. Tissue Eng Part C Methods 2017;23:219-227.