Fig. 1

3D bioprinted niche promotes cell differentiation and tissue incorporation. a Schematic illustration of the whole process of in vivo transplantation. b Scanning electron microscope (SEM) images and pore size of GelMA with 5%, 7.5% and 10% concentrations (Scale bar = 200 μm). c Viscosity of GelMA with 5%, 7.5% and 10% concentrations. d Stiffness of GelMA with 5%, 7.5% and 10% concentrations (10% vs. 7.5%, 7.5% vs. 5%, ^*P < 0.05). e Shape of bioprinted constructs (circle, triangle, square) in vitro and in vivo after 1 d and 7 d (Scale bar = 500 mm). f Degradation of hydrogel in vitro at days 1, 3, 5, 7, and 14, and the degradation of hydrogel and DiI-labeled cell tracing in vivo at days 3, 7, 14, 21, and 28 (Scale bar = 100 μm). g Proliferating cells were detected through Ki67 stain and comparison of stemness markers Oct-4 and Nanog between 2D (MSCs + PD) condition and 3D-bioprinted constructs (MSCs + PD + GelMA) at 1, 3, 5, 7 and 14 d of culture (DAPI: blue; scale bar = 50 μm). h Transcriptional expression of Ki67, Oct-4 and Nanog at days 1, 3, 5, 7, and 14 culture by quantitative real-time polymerase chain reaction (qRT-PCR). Data are mean ± SEM (standard error of mean) (3D vs. 2D, ^*P < 0.05). i Expression of SG-specific markers KRT18 and KRT8 at 3, 7 and 14 d of culture (KRT18: red; KRT8: green; DAPI: blue; scale bar = 50 μm). j Transcriptional expression of SG functional marker Atp1a1 and Aqp5 in 2D (MSCs + PD) condition and 3D condition (MSCs + PD + GelMA) in days 3, 7, and 14 culture (3D vs. 2D, ^*P < 0.05). k Expression of CK14 and GFP-labeled cells in SG after injection at days 3, 7, and 14 of MSCs + PD + GelMA group and iSGCs group (CK14: red; DAPI: blue; scale bar = 50 μm). l Expression of CD31 and GFP-labeled cells in SG after injection at day 3, 7, and 14 of MSCs + PD + GelMA group and iSGCs group (CD31: red; DAPI: blue; scale bar = 50 μm). m Macroscopic images of blood vessel formation in vivo after transplantation of MSCs + PD + GelMA group or MSCs + GelMA group at days 1, 3, 5, 7, and 14. n Detection and quantification of blood perfusion in vivo after transplantation of MSCs + PD + GelMA group or MSCs + GelMA group at days 1, 3, 5, 7, and 14 (MSCs + PD + GelMA group vs. MSCs + GelMA group, ^*P < 0.05). o Transcriptional expression of vascular induction genes Smoc2, Fgf9 and Lef1 in days 1 and 3 culture by qRT-PCR (MSCs + PD + GelMA group vs. MSCs + GelMA group, ^*P < 0.05). SG sweat gland, RSG regenerated sweat gland, BMSC bone marrow mesenchymal stem cell, MSCs mesenchymal stem cells, PD plantar dermis, iSGCs induced sweat gland cells, GelMA methacrylated gelatin