Engineering a vascularised bone tissue on electrospun biocomposite scaffolds

Bone has a self healing capacity regenerating itself without leaving a scar. However,critical size defects due to trauma, tumor, disease or infection require bone graft surgeries in which complication rate is high. Bone tissue engineering appears as an alternative for grafting.On the other hand, upon implantation bone tissue engineering constructs or the grafts generally fail due to insufficient vascularisation. In order to obtain vascularisation and mimic the local cellular environment of bone tissue, in vitro approaches began to involve heterotypic cells generally including bone forming cells and endothelial cells. Heterotypic interactions provide cells the cues required for differentiation, organization, and homeostasis.In this study, the aim was to perform in vitro studies for engineering a vascularised bone tissue. For that purpose, rat bone marrow stem cells (RBMSCs) were co-cultured with rat aortic andothelial cells (RAECs). Co-culture studies were first performed in 2D on tissue culture plates(TCPs). Then, co-cultured cells were seeded on poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) and hydroxyapatite (HAp) containing electrospun biocomposite scaffolds. Proliferation of RBMSCs with RAECs was determined on TCPs and on electrospun fibrous mats by MTS cell proliferation assay. The effect of co-culturing on differentiation of RBMSCs towards osteoblastic lineage was evaluated by alkaline phosphatase (ALP) assay and von Kossa staining for the detection of mineralization. Collagen Type I immunostaining were carried out to examine ECM formation by RBMSCs on electrospun fibrous mats. Cell morphologies on electrospun fibrous mats were observed by SEM.