Electrospun scaffolds for tissue engineering

Abstract

A critical challenge in designing materials for tissue engineering (TE) is to provide essential cues that can control cellular behaviour and promote tissue regeneration. TE with fibrous scaffolds by using electrospinning is emerging as a major research area in the field of regenerative medicine. This thesis presents the development of novel electrospun fibrous acrylate scaffolds for bone TE. Acrylate fibrous scaffolds were developed by electrospinning photocrosslinkable and low molecular weight acrylate monomers, methyl acrylate (MA) and diethylene-glycol dimethacrylate (DEGMA). Photocrosslinked fibres were successfully produced by electrospinning different MA and DEGMA compositions and post-UV crosslinking. The ability to produce topologically and mechanically diverse fibrous scaffold materials was demonstrated. Varying MA and DEGMA composition affected overall fibre morphology, swelling and mechanics of the fibrous scaffold. An assessment of biological activity of the acrylate fibrous scaffold was performed to evaluate the effect of varying ratios of MA/DEGMA of the fibrous scaffold on the viability of two different cell types, osteosarcoma-derived osteoblastic cells (Saos-2) and mesenchymal stromal cells (hMSCs). The potential of MA/DEGMA fibrous scaffolds to support Saos-2 cell viability and proliferation was demonstrated. However, the considerable increase in apoptosis of hMSCs cultured on both fibrous and flat samples suggested a lower potential of the MA/DEGMA scaffolds to support hMSCs cell attachment and viability. The fibrous scaffolds were immobilized with synthetic peptides utilizing cysteine-functionalized RGD or DGEA peptide sequences in combination with MA/DEGMA monomers and by employing a photoinitiated mixed-mode thiol-acrylate polymerization mechanism. Cysteine-functionalized DGEA and RGD peptides were incorporated efficiently in the synthesized acrylate scaffold. The peptide-conjugated fibrous scaffolds showed increased hMSCs adhesion and viability. Through cell adhesion and soluble peptide competition assays, the bioactivity and specificity of each peptide conjugated to the scaffold was confirmed. Finally, hMSCs cultured on DGEA conjugated scaffolds exhibited the activation of osteogenic differentiation markers, alkaline phosphatase (ALP) and osteocalcin (OCN). The results presented in this thesis strongly suggest the potential of the acrylate fibrous scaffold for bone TE.