Bone tissue regeneration: The role of finely tuned pore architecture of bioactive scaffolds before clinical translation

Spatial dimension of pores and interconnection in macroporous scaffolds is of particular importance in facilitating endogenous cell migration and bone tissue ingrowth. However, it is still a challenge to widely tune structure parameters of scaffolds by conventional methods because of inevitable pore geometrical deformation and poor pore interconnectivity. Here, the long-term in vivo biological performances of nonstoichiometric bio ceramic scaffolds with different pore dimensions were assessed in critical-size femoral bone defect model. The 6% Mg-substituted wollastonite (CSi-Mg6) powders were prepared via wet-chemical precipitation and the scaffolds elaborately printed by ceramic stereolithography, displaying designed constant pore strut and tailorable pore height (200, 320, 450, 600 mu m), were investigated thoroughly in the bone regeneration process. Together with detailed structural stability and mechanical properties were collaboratively outlined. Both mu CT and histological analyses indicated that bone tissue ingrowth was retarded in 200 mu m scaffolds in the whole stage (2-16 weeks) but the 320 mu m scaffolds showed appreciable bone tissue in the center of porous constructs at 6-10 weeks and matured bone tissue were uniformly invaded in the whole pore networks at 16 weeks. Interestingly, the neotissue ingrowth was facilitated in the 450 mu m and 600 mu m scaffolds after 2 weeks and higher extent of bone regeneration and remodeling at the later stage. These new findings provide critical information on how engineered porous architecture impact bone regeneration in vivo. Simultaneously, this study shows important implications for optimizing the porous scaffolds design by advanced additive manufacture technique to match the clinical translation with high performance.