Microporosity mediated proliferation of preosteoblast cells on 3D printed bone scaffolds

Abstract

Microporous structure plays a significant role in bone tissue engineering, to influence inductive bone formation and elevate bone ingrowth inside microporous scaffolds. We hereby fabricated microporous scaffolds by 3D printing with mixture of porogens and photopolymerizing resin. Our method can tune the microporosity of scaffolds from 0% to 36% by varying the porogen concentration in the inks from zero to 60 vol%. The microporosity and microspore size of scaffolds can affect in vitro expansion of preosteoblast cells. We evaluated the attachment, spreading and proliferation of MC3T3-E1 mouse preosteoblast cells on the printed porous scaffolds. Our studies revealed that preosteoblast cells' in vitro adhesion and proliferation were significantly mediated by the printed scaffolds. Cells proliferation on scaffolds with 20%-30% microporosity showed much higher rate than on other scaffolds. In this microporosity range, scaffolds also showed much better cell spreading and morphologies. At a low level of microporosity (< 7%), the cell proliferation rate was even lower than the solid scaffolds, which indicates that the microporous structure is "toxic" for cells at low microporosity range. A higher microporosity (> 35%) led to very poor cell attachment and is unfavorable for the proliferation of MC3T3-E1 cells. Furthermore, the printed dual macro-/micro-porous scaffolds showed higher proliferation rate of MC3T3-E1 cells as compared to mono-pore sized scaffolds, either the macro-porous or microporous structure. K E Y W O R D S3D printing, additive manufacturing, bone tissue engineering, microporosity, vat photopolymerization INTRODUCTIONAnnually, millions of bone transplants are performed worldwide. [1] Traditional autografts and allografts have been used for decades, but they have many limitations, including the limited size and supply, the risk of diseaseThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Simple Fabrication and Enhanced Bioactivity of Bioglass‐Poly(lactic‐co‐glycolic acid) Composite Scaffolds with Matrix Microporosity

“…However, calcite formation is not desirable, as the bioactivity of calcite is based on its transformation to HA. [39,40,104,105] Raman spectra of both scaffolds (Figure S14, Supporting Information) further confirmed HA formation showing the emergence of a strong peak at 962 cm −1 (𝜈 sym(OPO) ) after 7 and 14 days of SBF immersion.…”

“…However, calcite formation is not desirable, as the bioactivity of calcite is based on its transformation to HA. [ 39,40,104,105 ]…”

“…[37] However, despite promoting greater initial cell adhesion, scaffolds with only micropores do not allow for cell infiltration in the bulk of the scaffold. [38,39] Another important factor to be considered in microporous scaffold design is the degradation rate. The enhanced surface area and high permeability in microporous scaffolds can accelerate their degradation.…”

“…Given the different benefits of both pore types, a scaffold combining macropores and micropores could be an excellent candidate for bone tissue engineering. [28,[42][43][44][45][46] In two recent examples, MC3T3 pre-osteoblasts proliferated more abundantly on polyethylene glycol like scaffolds composed of polymerized diethylene glycol diacrylate with dual macro and microporous structures compared to scaffolds with either macropores or micropores; [39] and bone ingrowth in macroporous tricalcium phosphate scaffolds decreased with decreasing microporosity upon implantation in rabbit calvarial defect model, highlighting the importance of dual-scale porosity. [46] There are a few techniques to introduce porosity in composite scaffolds.…”

Polyhedral Oligomeric Silsesquioxane as a Polarity Mediator and Reinforced Nanofiller for Fabricating Robust and Hierarchical Porous Film for Cell Bioengineering

“…By using water-in-poly­(dimethylsiloxane) (PDMS) emulsion templating, Malaquin fabricated highly interconnected porous polymer structures for three-dimensional (3D) cell cultures . Recently, we reported the successful 3D printing of porous bioscaffolds by combining DLP printing and porogen templating . The results showed that a macroporous structure larger than 200 μm could be achieved through 3D printing while the microporous structure (from nanometer to micrometer) could be controlled by the porogen concentration.…”