hPSC-Derived Striatal Cells Generated Using a Scalable 3D Hydrogel Promote Recovery in a Huntington Disease Mouse Model

Abstract

Huntington disease (HD) is an inherited, progressive neurological disorder characterized by degenerating striatal medium spiny neurons (MSNs). One promising approach for treating HD is cell replacement therapy, where lost cells are replaced by MSN progenitors derived from human pluripotent stem cells (hPSCs). While there has been remarkable progress in generating hPSC-derived MSNs, current production methods rely on two-dimensional culture systems that can include poorly defined components, limit scalability, and yield differing preclinical results. To facilitate clinical translation, here, we generated striatal progenitors from hPSCs within a fully defined and scalable PNIPAAm-PEG three-dimensional (3D) hydrogel. Transplantation of 3D-derived striatal progenitors into a transgenic mouse model of HD slowed disease progression, improved motor coordination, and increased survival. In addition, the transplanted cells developed an MSN-like phenotype and formed synaptic connections with host cells. Our results illustrate the potential of scalable 3D biomaterials for generating striatal progenitors for HD cell therapy.

Keywords: Huntington disease; biomaterials; cell replacement therapy; differentiation; human pluripotent stem cells; medium spiny neurons.

Figure 1

Optimizing MSN Differentiation in Three Dimensions (A) Development of LGE progenitors. Antagonistic DKK1 and WNT signaling give rise to the telencephalon in the rostral forebrain (blue inset). In the posterior telencephalon (red inset), antagonistic WNT and SHH signaling produce the LGE progenitors. (B) Schematic and media conditions for MSN differentiation optimization in three dimensions. H1 hESCs encapsulated in hydrogels were differentiated into LGE progenitors for 26 days and subsequently matured into MSNs on laminin-coated plates. Three different protocols were tested (M1, M2, and M3) with varying WNT/SHH modulation (X) and basal medium (Y). (C) qPCR at D28 of differentiation for media conditions M1, M2, and M3, showing log₂ gene expression normalized to GAPDH. (D) Representative immunocytochemistry images at D45 for conditions M1, M2, and M3, showing CALBINDIN (red, left panels), DARPP32 (red, center panels), and GABA (red, right panels), with MAP2 (green) and nuclei labeled with DAPI (blue). Scale bars represent 20 μm. (E) Quantification of immunocytochemistry results showing the percentage of total cells positive for DARPP32, CALBINDIN, and GABA for conditions M1, M2, and M3. Data are presented as mean ± SEM for n = 3 independent experiments. ^∗p < 0.05 for unpaired t test.

Figure 2

In vitro MSN Maturation and Action Potential Firing at D60 (A–D) Striatal progenitors were generated using condition M3 in 3D hydrogels for 26 days, then subsequently plated and matured on 2D laminin-coated plates until D60 for histology and live imaging analysis. Representative immunocytochemistry images showing co-expression of (A) DARPP32 (red), CTIP2 (yellow), MAP2 (cyan), and nuclei (labeled with DAPI, blue); (B) CALBINDIN (red) with MAP2 (green); (C) GABA (red) with MAP2 (green); and (D) GFAP (red) with MAP2 (green). Scale bars represent 50 μm. (E and F) Quantification of the fraction of cells positive for markers of interest. Data are presented as mean ± SEM for n = 3 independent experiments. (G–J) Voltage-sensitive dye-based recording of spontaneously fired action potential in striatal cultures. (G) Representative bright-field image of recorded cells. (H and I) Plots of ΔF/F versus time for cells labeled in (G). (J) Raster plot showing spiking frequencies for all recorded cells, firing and non-firing.

Figure 3

Transplantation of 3D-Derived Striatal Progenitors Provides Therapeutic Benefit to HD Mice (A–D) Striatal progenitors generated in 3D hydrogels for 26 days were matured on laminin-coated surfaces for 10 days before harvest and bilateral striatal transplantation into 5-week-old R6/2 mice. Starting 2 weeks after transplantation, disease progression was monitored weekly with (B) clasping, (C) rotarod, and (D) weight change for R6/2 HD mice (purple; n = 12), control untreated HD mice (green; n = 16), and wild-type (WT) mice (gray; n = 11). ^∗∗∗∗p < 0.0001 and ^∗p < 0.05 for one-way ANOVA with Tukey's test for multiple comparisons. (E) Survival data shown in a Kaplan-Meier plot. (F) Mean survival for treated (n = 12) and untreated R6/2 mice (n = 16). ^∗p < 0.05 for Welch's unpaired t test. Data are shown as means ± SEM. See also Figure S3.

Figure 4

Survival and Integration of Grafted Human Cells (A–D) R6/2 or wild-type mice transplanted with D35 striatal neurons were sacrificed 12–15 weeks post transplantation, corresponding with an overall age of 17–20 weeks. Representative immunohistochemistry images showing expression of HNA (red) and DARPP32 (green) in (A) R6/2 mice or (B) wild-type mice. Co-labeling with Fluorogold (FG, blue) demonstrates connectivity with the substantia nigra. hNCAM (yellow) expressing human cells in (C) sparse surviving graft in R6/2 mice or (D) robust graft in wild-type mice. (E) Nuclear-localized HTT aggregates (red) were seen in many of the hNCAM (green) expressing human cells, some of which are indicated by white arrows, in R6/2 mice. (F) No HTT aggregates were seen in hPSC-derived MSNs transplanted in wild-type mice. Scale bars represent 50 μm. See also Figure S4.