Directed Induction of Functional Multi-ciliated Cells in Proximal Airway Epithelial Spheroids from Human Pluripotent Stem Cells

Abstract

Multi-ciliated airway cells (MCACs) play a role in mucociliary clearance of the lung. However, the efficient induction of functional MCACs from human pluripotent stem cells has not yet been reported. Using carboxypeptidase M (CPM) as a surface marker of NKX2-1(+)-ventralized anterior foregut endoderm cells (VAFECs), we report a three-dimensional differentiation protocol for generating proximal airway epithelial progenitor cell spheroids from CPM(+) VAFECs. These spheroids could be induced to generate MCACs and other airway lineage cells without alveolar epithelial cells. Furthermore, the directed induction of MCACs and of pulmonary neuroendocrine lineage cells was promoted by adding DAPT, a Notch pathway inhibitor. The induced MCACs demonstrated motile cilia with a "9 + 2" microtubule arrangement and dynein arms capable of beating and generating flow for mucociliary transport. This method is expected to be useful for future studies on human airway disease modeling and regenerative medicine.

Graphical abstract

Figure 1

Generation of PAEPC Spheroids from CPM⁺ VAFECs in 3D Culture (A) Stepwise differentiation to PAEPC spheroids from hPSCs. (B) qRT-PCR of NKX2-1 expression in each hPSC line on day 14, according to the dose of BMP4. The concentrations of BMP4 for each condition in Step 3 are shown in the columns. Each value was normalized to β-ACTIN. The gene expression level of the fetal lungs was set at 1. Error bars represent the mean ± SEM (n = 3 independent experiments). Each condition was compared with condition b for each hPSC line; ^∗p < 0.05. N/A, not applicable. (C) CPM⁺ VAFEC-derived spheroids (201B7 hiPSCs) on days 18, 21, and 28. (D) CIF imaging shows 201B7 hiPSC-derived PAEPC spheroids coexpressing SOX2 and NKX2-1 on day 28. Scale bars, 100 μm. See also Figure S1 and Tables S1 and S2.

Figure 2

Derivation of PAECs from PAEPC Spheroids (A) A schematic illustration of the induction of PAECs from hPSC-derived PAEPC spheroids. (B) H&E staining of PAEC spheroids (201B7 hiPSCs) on day 42 shows spheroids (left) and clusters of MCACs in a magnified view (right). (C) Double immunostaining of PAEC spheroids (201B7 hiPSCs) on day 42. Fetal human lung was shown as a positive control. Adult human thyroid (AHT) was shown as a negative control for Ac-Tub and FOXJ1, whereas fetal human liver (FHLiv) was shown as a negative control for Ac-Tub, FOXJ1, MUC5AC, SYP, and CHGA. The white circle indicates MUC5AC⁺ cells. (D) Double immunostaining of induced PAEC spheroids (201B7 hiPSCs) on day 42. SCGB1A1, KRT5, CHGA, and SYP were detected in NKX2-1⁺ cells. (E) Triple immunostaining of PAEC spheroids (201B7 hiPSCs) on day 42. FOXJ1, SCGB1A1, and KRT5 were detected in the different cells. Scale bars, 50 μm. See also Figure S2 and Table S2.

Figure 3

Directed Induction of MCACs and PNECs by Adding DAPT (A) A schematic illustration of each protocol for induction of PAECs, according to CPM-based sorting and the addition of DAPT. (B–E) qRT-PCR of representative PAEC markers: FOXJ1, DNAH5, and SNTN for MCACs (B), SCGB1A1 and SCGB3A2 for club cells (C), CGRP, CHGA, and SYP for PNECs (D), and MUC5AC and SPDEF for mucus-producing cells (E). Each value was normalized to β-ACTIN. The gene expression of the fetal trachea sample was set at 1. Error bars represent the mean ± SEM (n = 3 independent experiments; ^∗p < 0.05). (F) The induction efficiency of MCACs and PNECs calculated by counting the number of FOXJ1⁺, CHGA⁺, and SYP⁺ cells (Supplemental Experimental Procedures). Error bars represent the mean ± SEM (n = 3 independent experiments). Protocol c was compared with protocol b for each hPSC line; ^∗p < 0.05, ^∗∗p < 0.01. (G) H&E staining of DAPT-induced 3D spheroids (201B7 hiPSCs) on day 56 (upper panel) showed consecutively aligned MCACs in a magnified view (lower panel). (H) Double and triple immunostaining of MCAC markers in DAPT-induced PAEC spheroids (201B7 hiPSCs) on day 56. Magnified views were shown in lower panels. (I) Double immunostaining of CHGA or SYP (PNEC markers) with FOXJ1 in DAPT-induced PAEC spheroids (201B7 hiPSCs) on day 56. None of the markers was expressed in FOXJ1⁺ cells. Scale bars, 25 μm. See also Figure S3 and Tables S1 and S2.

Figure 4

Characterization of Motile Cilia of hPSC-Derived MCACs (A) Transmission electron microscopy of DAPT-induced PAEC spheroids (201B7 hiPSCs) on day 56 (leftmost panel). Multiple cilia were originated from basal bodies (second left panel, arrowheads). A cross-sectional image of multiple cilia of induced MCACs (second right panel) was magnified to show the “9+2” structure with dynein arms (rightmost panel, circles). (B) A schematic illustration of the preparation of hPSC-derived MCACs for ciliary function tests. In the “3D protocol,” MCACs were differentiated until day 56 in spheroids. In the “3D-ALI protocol,” PAECs were dissociated from 3D Matrigel blocks on day 42, followed by replating and culturing under ALI condition until day 56. (C) Double immunostaining of Ac-Tub and SNTN in 201B7 hiPSC-derived MCACs cultured in the 3D-ALI protocol. (D) qRT-PCR of FOXJ1, DNAH5, SNTN, and CFTR expression in hPSC-derived MCACs cultured in the 3D and 3D-ALI protocols (n = 3 independent experiments). Each value was normalized to β-ACTIN. The gene expression of the fetal trachea sample was set at 1. NS, not significant. (E) The CBF of MCACs in spheroids and 3D-ALI condition in each hiPSC line in three independent experiments (n = 198, 135, and 314 cells in the spheroids and n = 174, 236, and 519 cells in the 3D-ALI condition derived from 201B7, 585A1, and 604A1 hiPSCs, respectively). NHBEC-derived MCACs were used as positive controls in each condition in three independent experiments (n = 123 and 86 in the 3D and the ALI condition, respectively). The CBF in the spheroids was compared with that in the 3D-ALI condition for each hiPSC line; ^∗p < 0.05. (F) Stacked images of the fluorescent beads placed on 201B7 hiPSC-derived MCACs (left panel), and Brownian motion (right panel) acquired for 14.2 s. Color spectrum reflected time course. (G) The MTI of MCACs calculated from >100 trajectories of the fluorescent beads per sample in each hiPSC line in three independent experiments (n = 109, 142, 174, and 147 trajectories in 201B7, 585A1, and 604A1 hiPSCs and NHBECs, respectively). The MTIs in hiPSC-derived MCACs were compared with Brownian motion (n = 50) for each hiPSC line; ^∗∗p < 0.01. Error bars in the qRT-PCR, CBF, and MTI analyses represent the mean ± SEM. Scale bars, 25 μm unless otherwise indicated. See also Figure S4; Movies S1 and S2; and Tables S1 and S2.