Fig. 1: Chemically induced spontaneously contracting clusters from hUCs.

a A representative contracting cluster induced by 9 C on reprogramming day 30, n = 3. See also Supplementary Movie 1. Scale bars, 200 µm. b Screening for compounds promoting for contracting clusters induction. Number of beating clusters at day 30 is shown. Data are means ± SD, n = 3. *P < 0.05; **P < 0.01；***P < 0.001. Exact p-values are provided in a file named Supplementary Data 5. c Screening for compounds essential for contracting clusters induction. Number of beating clusters on day 30 are shown, n = 3. Exact p-values are provided in a file named Supplementary Data 5. d Schemes of different combinations of different reprogramming mediums. e Induction of beating clusters with 15 C under different schemes, n = 3. f Induction of beating clusters with 15 C under scheme 6 on different day, n = 3. g The scheme of direct cardiac reprogramming from hUCs with small molecule cocktails. hUCs are plated in urine cell growth medium for one day, and then the medium is changed into cardiac reprogramming medium (CRM) containing the small molecule cocktails. On day 30, the medium was changed into cardiomyocyte-purified medium for 4 days. After purification, the medium was changed into cardiomyocyte-maintaining medium (CMM). The first beating clusters could be observed on day 15–20, n = 3. h Morphology of the representative contracting clusters induced by 15 C, n = 9. See also Supplementary Movie 2 and Supplementary Movie 3. Scale bars, 100 µm. i Flow cytometry analyses of the percentage of cTnt⁺ cells on day 30 and day 60. Dot plots represent data from 23,546 events for hCiCMs-P0 and 85,627 events for hCiCMs-P1. The gating strategy is detailed in Supplementary Fig. S3.