Heparinized bioactive hybrid scaffolds for promoting and improving bone angiogenesis

Najera Romero, Griselda Valeria and Rehman, Ihtesham (2021) Heparinized bioactive hybrid scaffolds for promoting and improving bone angiogenesis. PhD thesis, Lancaster University.

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Abstract

Formation of blood vessels at required number and time during bone regeneration represents a major challenge for tissue engineered constructs. Poor revascularization leads to scaffold failure and consequently, the loss of the implant. There are several problems associated with the use of growth factors in clinic such as low stability, controlled delivery to the site, and high price. Heparin is known to bind with angiogenic growth factors influencing the process of new blood vessels formation. The aim of the present study was to explore the potential of heparin to produce pro-angiogenic bone regeneration materials. Heparin was electrostatically loaded onto composite materials from porous chitosan/hydroxyapatite scaffolds. Different concentrations of heparin were successfully loaded onto the scaffolds, and the release performance of the scaffold was analysed by toluidine blue assay showing that the scaffolds loaded with lowest concentration provide a sustained release. The angiogenic activity of the heparin loaded synthesized materials was evaluated by chorioallantoic membrane (CAM) assay. After six day of materials implantation on CAM it was noted that overall low heparin concentrations exhibited a positive effect, with approximately 28μg per scaffold showed a significant increment in blood vessels. The synthesized materials showed no cytotoxic effects when evaluated by using U2OS cell line. Also, as showed by the SEM images the scaffolds exhibited that interconnected porosity and a pore size able to support osteoblasts proliferation. This research provides information about the pro-angiogenic effect of heparin in potential bone regeneration materials.