Development of Anatomical Silk/Methacrylated Gellan Gum Scaffolds for Controlling Segmental Vascularization in Meniscus Tissue Regeneration

Meniscus tissue engineering can benefit from the use of highly developed scaffolds that are able to mimic the anatomy of this complex tissue, i.e. enable controlling the segmental vascularization during tissue regeneration. In this work, novel scaffolds were produced combining a porous silk polymeric matrix at 12 wt% (silk-12) and the methacrylated gellan gum hydrogel (iGG-MA), which was previously shown to be non-angiogenic. A chorioallantoic membrane (CAM) assay was used to investigate the ability of the silk-12/iGG-MA scaffolds to control cell ingrowth, segmental vascularization, and innervations. Different sterile silk-based scaffolds were tested on the CAM, which were composed by silk-12 alone or combined with iGG-MA hydrogel and/or human meniscus cells. The angiogenic response was evaluated after 4 days of implantation by analysing the number of blood vessels converging toward the scaffolds, whereas possible inflammation and endothelial cells ingrowths’ was investigated by histological (haematoxylin and eosin - H&E - staining) and immunohistochemical methods (SNA-lectin staining). Results have shown that silk-12 are highly susceptible to cells ingrowths’ and blood vessel formation. However, when the hydrogel was combined with the silk-12, an inhibitory effect was observed as demonstrated by the low number of convergent blood vessels and less number of endothelial cells invading the silk-12/iGG-MA scaffolds. The iGG-MA hydrogel acted as a physical barrier for endothelial cells ingrowths’ and vascular invasion. This data showed that silk-12/iGG-MA scaffolds are not toxic, enabled controlling vascularisation and thus can be potentially applied in meniscus regeneration.