Fig.1 Schematic illustration for the fabrication of trilayer tissue engineering scaffolds for uterine tissue regeneration. (A) 3D printing of the PTMC/TPU scaffold layer. (B) Electrospinning to fabricate the E2-containing PLGA/GelMA fibrous layer on the PTMC/TPU scaffold layer. (C) 3D bioprinting to construct the BMSC-laden hydrogel layer on the PLGA/GelMA fibrous layer to complete the fabrication of designed biomimicking trilayer tissue engineering scaffold.

PTMC (molar ratio of LA:TMC = 8:2 and dl/g 0.9) and PLGA (molar ratio of LA:GA =50:50 and average molecular weight of 90 kDa) were purchased from Jinan Daigang Ltd., China. TPU 95A was supplied by BASF SE, Germany. Estradiol (E2) was bought from Aladdin Co. Ltd., China. Gelatin (porcine skin, type A), bovine serum albumin (BSA), methacrylate anhydride (MA, 94%), ammonium hydroxide solution (NH₄OH) (28%), absolute ethanol, 2-hydroxy-2-methylpropiophenone (97%), 1,1,1,3,3-hexafluoro-2-propanol (HFIP) and dopamine hydrocholoride (98%) were bought from Sigma-Aldrich (St. Louis, MO, USA). Dialysis tubing cellulose membrane (MWCO 10kDa) was supplied by Thermo Fisher Scientific, USA. All reagents were used as received without further purification.