Bone marrow absorption and retention properties of engineered scaffolds with micro-channels and nano-pores for tissue engineering: A proof of concept

We have developed a hydroxyapatite-based scaffold with micro-channels and nano-pores (MCNP) using a polyurethane template coating method to overcome some of the limitations by addressing fluid absorbance and retention via capillary action. The novel scaffold has 3 basic structures. First, the scaffold has a porous trabecular network similar to that of human trabecular bones (300–400 um) which are mechanically matched to the strength of native trabecular bone (2–12 MPa). Second, it has micro-sized channels (25–70 um) within each trabecular septum which exhibit highly effective fluid absorption via capillary action. Third, the surface of each septum has nano-sized pores (100–400 nm) that allow immobilized cells to anchor. The surface area of the scaffold with micro-channels was significantly (+42.0%) higher than the scaffold without micro-channels as calculated using computer aided design (CAD) software, while overall porosity did not change significantly (+8.8%). Combinatorial effects of these internal structures result in a host-adapting construct that enhances cell ingress and retention from the host bone marrow throughout the entire scaffold.