3.4 In vitro biological performance of bilayer scaffolds
Many in vitro and in vivo studies have demonstrated the safety and efficacy of menstrual-derived stem cells (MenSCs) obtained from women’s menstrual fluids for repairing damaged uterine tissues[45]. Although MenSCs attract growing interest in clinical applications because they are multipotent and have high proliferation rate, the limited source and complex extraction procedure is problematic. A recent study has indicated that BMSCs had comparable properties as MenSCs had [46], suggesting that BMSCs could replace MenSCs for use in uterine regeneration. Additionally, many studies have demonstrated the efficacy of BMSCs for uterine regeneration in preclinical and clinical trials. BMSCs could differentiate into endometrium epithelial cells so as to improve gland and blood vessel formations and activate the resident endometrium stem cells to promote uterine regeneration via the paracrine effect[10b, 47]. Therefore, in the current study, BMSCs were used to evaluate the in vitro biological performance of bilayer scaffolds. Cell attachment results, as shown in Fig.S13, revealed that BMSCs cultured on S, S+F and S+F-PDA@E2 scaffolds all exhibited spread morphology, suggesting that all scaffolds were biocompatible. The live/dead assay results indicated that the BMSC survival rate in S, S+F and S+F-PDA@E2 scaffolds was over 90 % after cultured for 24 and 48 h, respectively [Fig.7(A)(B)]. However, the proliferation rates of BMSCs on those scaffolds were significantly different [Fig.7(C)]. Compared to S scaffolds (i.e., PTMC/TPU), S+F bilayer scaffolds and S+F-PDA@E2 bilayer scaffolds had higher proliferation rates, suggesting that electrospun PLGA/GelMA fibers on PTMC/TPU scaffolds had made scaffold surface hydrophilic and improved scaffold-cell interface behavior and thus promoted cell proliferation. Moreover, due to the PDA particles and sustained release of E2, S+F-PDA@E2 bilayer scaffolds had the highest proliferation rate, which was consistent with previous studies [40a, 44]. Furthermore, phalloidin/DAPI staining results in Fig.7(D) indicated that BMSCs maintained their phenotypes and showed spindle-like morphology on S+F and S+F-PDA@E2 bilayer scaffolds. Overall, S+F-PDA@E2 bilayer scaffolds had excellent biocompatibility and promoted BMSC growth.