Placenta Powder-Infused Thiol-Ene PEG Hydrogels as Potential Tissue Engineering Scaffolds

Human placenta is a source of extracellular matrix for tissue engineering. In this study, placenta powder (PP), made from decellularized human placenta, was physically incorporated into synthetic poly(ethylene glycol) (PEG)-based hydrogels via UV-initiated thiol-ene coupling (TEC). The PP-incorporated PEG hydrogels (MoDPEG+) showed tunable storage moduli ranging from 1080 ± 290 to 51,400 ± 200 Pa. The addition of PP (1, 4, or 8 wt %) within the PEG hydrogels increased the storage moduli, with the 8 wt % PP hydrogels showing the highest storage moduli. PP reduced the swelling ratios compared with the pristine hydrogels (MoDPEG). All hydrogels showed good biocompatibility in vitro toward human skin cells and murine macrophages, with cell viability above 91%. Importantly, cells could adhere and proliferate on MoDPEG+ hydrogels due to the bioactive PP, while MoDPEG hydrogels were bio-inert as cells moved away from the hydrogel or were distributed in a large cluster on the hydrogel surface. To showcase their potential use in application-driven research, the MoDPEG+ hydrogels were straightforwardly (i) 3D printed using the SLA technique and (ii) produced via high-energy visible light (HEV-TEC) to populate damaged soft-tissue or bone cavities. Taking advantage of the bioactivity of PP and the tunable physicochemical properties of the synthetic PEG hydrogels, the presented MoDPEG+ hydrogels show great promise for tissue regeneration.