This research is aimed at designing and developing a novel biomimetic hybrid scaffold for eye orbital floor defect repair where the load-bearing structure is a polyurethane (PU) foam and alginate gel is used as carrier for Mesenchymal stem cells (MSCs).

PU foam (PU) was synthesized via a one-step bulk polymerization method using water as expanding agent and iron-acetylacetonate as the catalyst. For the encapsulation of MSCs in the hydrogel, all works performed under sterile condition. Briefly, at first, foam samples were immersed in calcium chloride 0.25 M for 30 min and then coated by using a two syringe method; in particular, one syringe contained the PU sample, while the other contained the alginate solution and medium culture containing 1x104 MSCs as illustrated in figure1. For complete alginate gelification, the samples were immersed in calcium chloride solution 0.75 M. The Scaffolds were characterized by micro-CT, SEM, compression mechanical properties, and in vitro tests with MSCs stem cells.

PU foam showed a homogeneous porosity, with mostly spherical pore geometry and a high number of interconnections, as confirmed by micro CT analysis. SEM images of PU-alginate showed a thin continuous layer of gel, homogeneously distributed on all the surfaces. Compression mechanical tests showed σmax =30.56 ± 2.76KPa. The proliferation of MSCs encapsulated in alginate significantly increased over time (p<0.05).

This novel scaffold displayed morphologic, mechanical and biocompatibility properties suitable for bone defect repair of orbital floor. In vitro differentiation of encapsulated MSCs in the osteoblast phenotype will be the focus of future work.