Role of offset and gradient architectures of 3-D melt electrowritten scaffold on differentiation and mineralization of osteoblasts

Naghmeh Abbasi; Saso Ivanovski; Karan Gulati; Robert M Love; Stephen Hamlet

doi:10.1186/s40824-019-0180-z

Role of offset and gradient architectures of 3-D melt electrowritten scaffold on differentiation and mineralization of osteoblasts

Biomater Res. 2020 Jan 3:24:2. doi: 10.1186/s40824-019-0180-z. eCollection 2020.

Authors

Naghmeh Abbasi^{1

2}, Saso Ivanovski³, Karan Gulati³, Robert M Love¹, Stephen Hamlet^{1

2}

Affiliations

¹ 1School of Dentistry and Oral Health, Griffith University, Gold Coast Campus, Southport, Queensland 4215 Australia.
² 2Menzies Health Institute Queensland, Griffith University, Gold Coast Campus, Southport, Queensland 4215 Australia.
³ 3School of Dentistry, University of Queensland, Herston Campus, St Lucia, Queensland 4072 Australia.

Abstract

Background: Cell-scaffold based therapies have the potential to offer an efficient osseous regenerative treatment and PCL has been commonly used as a scaffold, however its effectiveness is limited by poor cellular retention properties. This may be improved through a porous scaffold structure with efficient pore arrangement to increase cell entrapment. To facilitate this, melt electrowriting (MEW) has been developed as a technique able to fabricate cell-supporting scaffolds with precise micro pore sizes via predictable fibre deposition. The effect of the scaffold's architecture on cellular gene expression however has not been fully elucidated.

Methods: The design and fabrication of three different uniform pore structures (250, 500 and 750 μm), as well as two offset scaffolds with different layout of fibres (30 and 50%) and one complex scaffold with three gradient pore sizes of 250-500 - 750 μm, was performed by using MEW. Calcium phosphate modification was applied to enhance the PCL scaffold hydrophilicity and bone inductivity prior to seeding with osteoblasts which were then maintained in culture for up to 30 days. Over this time, osteoblast cell morphology, matrix mineralisation, osteogenic gene expression and collagen production were assessed.

Results: The in vitro findings revealed that the gradient scaffold significantly increased alkaline phosphatase activity in the attached osteoblasts while matrix mineralization was higher in the 50% offset scaffolds. The expression of osteocalcin and osteopontin genes were also upregulated compared to other osteogenic genes following 30 days culture, particularly in offset and gradient scaffold structures. Immunostaining showed significant expression of osteocalcin in offset and gradient scaffold structures.

Conclusions: This study demonstrated that the heterogenous pore sizes in gradient and fibre offset PCL scaffolds prepared using MEW significantly improved the osteogenic potential of osteoblasts and hence may provide superior outcomes in bone regeneration applications.

Keywords: Bone differentiation; Melt electrowriting (MEW); Polycaprolactone (PCL); Pore size; Scaffold.