Figure 2. iSNs and Human DRG Neurons Co-express TRPM8 and PIEZO2.

(A) Heatmap of RNA sequencing results on iPSCs, iSNs, and adult human donor DRG (hDRG). Each column represents an individual sample’s normalized log₂ transcripts per million (TPM). The hDRG is a pooled RNA sample from 21 individuals.

(B) RNA in situ hybridization on iSNs for transcripts of neurotrophin and sensory receptors. Each small fluorescent punctum roughly indicates one transcript. TUBB3 encodes a general neuron class of microtubule, βIII-tubulin. Scale bars, 10 μm.

(C) Quantification of in situ hybridization in iSNs using a cutoff criteria of ≥ 5 puncta per transcript for positive cells. TRPM8⁺ (17.9% ± 1.5%), PIEZO2⁺ (14.0% ± 4.6%), TRPM8⁺/PIEZO2⁺ (56.0% ± 6.3%), and TUBB3⁺ only (11.5% ± 3.4%). 199 cells were counted across n = 5 coverslips.

(D) RNA in situ hybridization for TRPM8 and PIEZO2 in human DRG (hDRG). Labeled neurons are shown in wide-field view (left) with dotted, dashed, and solid circles indicating TRPM8⁺, PIEZO2⁺, and TRPM8⁺/PIEZO2⁺ neurons, respectively. Zoomed images of single neurons (right), individually marked by numbers in the wide-field view. Scale bars, 25 μm.

(E) Quantification of human DRG in situ hybridization. TRPM8⁺ (12.8% ± 4.4%), PIEZO2⁺ (59.7% ± 6.8%), and TRPM8⁺/PIEZO2⁺ (27.4% ± 6.9%). 622 positive cells were counted across n = 4 DRG donors. All values are expressed as mean ± SEM.

See also Figure S2 and Table S1.