Performance of degradable composite bone repair products made via three‐dimensional fabrication techniques

Abstract

This study analyzed the in vivo performance of composite degradable bone repair products fabricated using the TheriForm process, a solid freeform fabrication (SFF) technique, in a rabbit calvarial defect model at 8 weeks. Scaffolds were composed of polylactic-co-glycolic acid (PLGA) polymer with 20% w/w beta-tricalcium phosphate (beta-TCP) ceramic with engineered macroscopic channels, a controlled porosity gradient, and a controlled pore size for promotion of new bone ingrowth. Scaffolds with engineered macroscopic channels and a porosity gradient had higher percentages of new bone area compared to scaffolds without engineered channels. These scaffolds also had higher percentages of new bone area compared to unfilled control defects, suggesting that scaffold material and design combinations could be tailored to facilitate filling of bony defects. This proof-of-concept study demonstrated that channel size, porosity, and pore size can be controlled and used to influence new bone formation and calvarial defect healing.

Angiogenesis and bone regeneration of porous nano-hydroxyapatite/coralline blocks coated with rhVEGF165 in critical-size alveolar bone defects in vivo

“…High levels of interconnectivity between the pores enhance the porosity and enlarge the superficial area and consequently increase the numbers of endothelial cells and active osteoblasts. 35,36 It is important to note that our histological evidence revealed obvious cell migration from the peripheries to the cores of the nHA/coral blocks at the 3-week time point; collagen matrices were also readily observable in the centers. There were more newly formed blood vessels and greater quantities of bone tissue present at the 8-week time point.…”

Vascularized Bone Tissue Engineering: Approaches for Potential Improvement

“…Roy et al found that in a PLGA/b-TCP composite scaffold with a porosity gradient from 80% to 88%, bone tissue formation was enhanced in the region with higher porosity after implantation in rabbit craniums. 123 Kruyt et al also demonstrated higher proliferation of goat bone marrow stromal cells in hydroxyapatite scaffolds with 70% porosity and an average pore size of 800 mm compared to those with 60% porosity and an average pore size of 700 mm during a 6-day ex vivo culture. 124 However, in vitro osteogenesis has been shown to increase with lower porosity.…”

Controlling the Porosity and Microarchitecture of Hydrogels for Tissue Engineering

“…7,8 The pore interconnectivity allows for cell ingrowth, vascularization, and nutrient diffusion for cell survival. [9][10][11] The extent of ECM secretion also increases by increasing the pore size. 8 It was found that in genipin crosslinked gelatin hydrogels with smaller pores, the tendency was tilted toward cell growth rather than of ECM secretion, 8 resulting in overconfluence during the middle and late stages of differentiation; consequently, the extent of ECM secretion decreased compared to that within gelatin hydrogels with larger pores.…”