Page 378 - IJB-9-5

International Journal of Bioprinting Vascularized bone regeneration

1. Introduction dimensional (3D) printing technology has significant
advantages in preparing artificial bones with specific
The number of patients with bone defects caused by shapes . The challenge lies in how to prepare bioglass gel
[28]
factors such as osteoporosis, bone tumors, and infections with printing ability, and related research shows that it is
is growing rapidly, creating a huge clinical demand [1-3] . possible to solve this problem by grafting double bonds
Autologous and allogeneic bone transplantation are on polymer chains and further initiating polymerization
internationally recognized gold standards, but their through blue light . Insufficient mechanical strength is a
[22]
clinical application is greatly limited due to limited sources major bottleneck for large bone repair . To address this
[17]
and immune rejection [4-6] . Regulating cell behavior with issue, rigid powder particles are added to the biologically
bioactive materials has become an important means of active gel to enhance its strength, and crosslinking
tissue regeneration [7-9] . Developing bioactive inducing groups (e.g., -NH , -COO-, etc.) are grafted onto the
2
materials that can regulate bone tissue regeneration and surface of bioglass particles to improve interfacial
actively promote repair functions is currently a bottleneck compatibility [12,32,33] . Adjusting the composition ratio of
problem that limits the clinical transformation of tissue bioglass is the main means of regulating degradation.
regeneration technology [10-13] . Bioglass materials and Furthermore, integrating phosphate tetrahedral units
calcium phosphate materials are highly biocompatible into the glass network as a component of the secondary
and absorbable, and their degradation products can network improves network connectivity and resists
provide a precise bone regeneration microenvironment degradation . Significant progress has been made in
[30]
for cells, making them an important direction for clinical functionalizing bioglass to improve its processing ability,
application of bone regeneration-inducing materials [14-20] . mechanical strength, and degradation behavior, which
Among them, biologically active glass materials can form may meet clinical translational needs .
[34]
an effective bond with the surrounding bone tissue, and
2+
the degradation releases various ions (Ca , SiO , PO , In this study, a photocurable mesoporous bioglass
4-
3-
4
4
etc.) and trace elements (Mg, Cu, Sr, Ce, etc.) to stimulate (PMBG) sol was developed by grafting a silane coupling
bone tissue regeneration and repair [21-25] . Additionally, agent (3-(trimethoxysilyl) propyl methacrylate, TMSPMA)
mesoporous bioactive glass (MBG) possesses a highly onto the bioglass sol, and further composite with tricalcium
organized pore structure, offering a significant surface phosphate (TCP) particles to prepare personalized, highly
area and favorable biocompatibility, which is conducive porous scaffolds using 3D printing technology, which were
to the penetration and adsorption of biological and tissue then sintered for bone defect repair. During the hydrolysis
[25]
fluids . The multilevel pore structure (mesopores– of tetraethyl orthosilicate (TEOS), TMSPMA underwent
micropores–macropores) provides a good environment for condensation reaction with the hydrolysis product silanol
cell adhesion, proliferation, tissue growth, and migration, (Si-OH) to graft onto the bioglass sol, and the double
[26]
and also facilitates angiogenesis and growth . These bonds in the printing ink were crosslinked and cured
materials are widely used in orthopedics and dentistry. under blue light (405 nm) when leaving the nozzle. The
Despite this, there are still many characteristics that ink exhibited good printing performance and enabled
cannot meet the needs of bone tissue regeneration and precise preparation of large segment defects and complex
defect repair, mainly including: (i) the lack of personalized structures. As shown in Scheme 1, the printed scaffolds were
preparation processes, which cannot accurately match dried and sintered, and the phosphate units were integrated
specific bone defect structures and cannot meet the into the bioglass network. This study investigates the effects
demands for high porosity and connectivity of the scaffold of regulating the content of TCP on both the mechanical
during bone regeneration; (ii) low mechanical strength, properties and degradation behavior of scaffolds. Finally,
which cannot meet the mechanical strength requirements the microenvironment for bone repair constructed by
for large-sized implants, tissue regeneration, and defect the degradation products of the biphasic scaffold and
repair; and (iii) the degradation rate does not match the its relevant mechanisms for promoting vascularization
tissue regeneration rate, which seriously affects tissue and inducing stem cell osteogenic differentiation were
regeneration [25,27,28] . investigated in depth. The PMBG/TCP scaffold developed
in this study exhibited excellent comprehensive properties
Currently, bioglass is mainly prepared by sol- and has great potential for clinical application.
gel method, which has advantages such as high
controllability, good biocompatibility, and strong 2. Experimental design and procedures
scalability [29,30] . However, the preparation process is
cumbersome and time-consuming, and the production 2.1. Materials
cost is high. Personalization of bone repair scaffolds The materials used in this study include Pluronic® F-127
cannot be achieved by further template method . Three- (EO106PO70EO106) from Sigma-Aldrich (St. Louis,
[31]
Volume 9 Issue 5 (2023) 370 https://doi.org/10.18063/ijb.767