A comparative analysis of scaffold material modifications for load-bearing applications in bone tissue engineering

Abstract

To facilitate optimal application of appropriate scaffold architectures for clinical trials, there is a need to compare different scaffold modifications under similar experimental conditions. In this study was assessed the effectiveness of poly-e-caprolactone (PCL) scaffolds fabricated by fused deposition modelling (FDM), with varying material modifications, for the purposes of bone tissue engineering. The incorporation of hydroxyapatite (HA) in PCL scaffolds, as well as precalcification through immersion in a simulated body fluid (SBF) to produce a biomimetic apatite coating on the scaffolds, was assessed. A series of in vitro studies spanning 3 weeks as well as in vivo studies utilizing a subcutaneous nude mouse model were carried out. PCL and HA-PCL scaffolds demonstrated increasing tissue growth extending throughout the implants, as well as superior mechanical strength and mineralization, as evidenced by X-ray imaging after 14 weeks in vivo. No significant difference was found between PCL and HA-PCL scaffolds. Precalcification with SBF did not result in increased osteoconductivity and cell proliferation as previously reported. Conversely, tensile forces exerted by tissue sheets bridging adjacent struts of the PCL scaffold caused flaking of the apatite coating that resulted in impaired cell attachment, growth and mineralization. The results suggest that scaffolds fabricated by FDM may have load-bearing applications.

Fabrication, mechanical and in vivo performance of polycaprolactone/tricalcium phosphate composite scaffolds

“…Wiria et al [23] reported on the in vitro cell ingrowth of PCL/HA scaffolds fabricated via SLS, however, even though the success of the addition of a bioactive phase is anticipated, the in vivo performance of such composite scaffolds has not been extensively reported. Reports on in vivo testing of PCL based scaffolds fabricated by other rapid prototyping techniques are limited to small animal models [30][31][32][33][34][35][36].…”

Interaction of cell culture with composition effects on the mechanical properties of polycaprolactone-hydroxyapatite scaffolds fabricated via selective laser sintering (SLS)

“…Since bone is an extremely anisotropic composite material, methods that can potentially provide a similar scaffold structure are of utmost interest [1] and [2]. Solid freeform fabrication (SFF) technologies such as selective laser sintering (SLS) have been adapted for fabricating such tissue engineering scaffolds [3], [4] and [5].…”

“…Nevertheless, there are conflicting short-term results reported in literature about the effect of HA addition to PCL composites in terms of cell attachment, proliferation and differentiation. Some authors claim that the presence of HA in PCL scaffolds has little or no effect on biological response [4], [24], [25] and [26]. Others have shown that scaffolds with 25 wt.% of HA demonstrate improved cell differentiation compared to PCL scaffolds [27].…”

Selective laser sintering of hydroxyapatite/poly-ε-caprolactone scaffolds

“…There are conflicting short-term results reported in the literature about the effect of HA addition to PCL composites in terms of cell attachment, proliferation and differentiation. Some authors have discussed how the presence of HA in PCL scaffolds has little or no effect on biological response [20,[23][24][25]. Others showed that scaffolds with 25 wt.% HA demonstrate improved cell differentiation com-pared with PCL scaffolds [26].…”