Functional Hydrogels and Their Applications in Craniomaxillofacial Bone Regeneration

Abstract

Craniomaxillofacial bone defects are characterized by an irregular shape, bacterial and inflammatory environment, aesthetic requirements, and the need for the functional recovery of oral-maxillofacial areas. Conventional clinical treatments are currently unable to achieve high-quality craniomaxillofacial bone regeneration. Hydrogels are a class of multifunctional platforms made of polymers cross-linked with high water content, good biocompatibility, and adjustable physicochemical properties for the intelligent delivery of goods. These characteristics make hydrogel systems a bright prospect for clinical applications in craniomaxillofacial bone. In this review, we briefly demonstrate the properties of hydrogel systems that can come into effect in the field of bone regeneration. In addition, we summarize the hydrogel systems that have been developed for craniomaxillofacial bone regeneration in recent years. Finally, we also discuss the prospects in the field of craniomaxillofacial bone tissue engineering; these discussions can serve as an inspiration for future hydrogel design.

Keywords: bone regeneration; craniomaxillofacial bone; delivery system; hydrogel; stimuli-responsive system; tissue engineering.

Figure 2

Schematic representation of the communication between hydrogel and the cell. Modulation of various modifiable physicochemical properties of the hydrogel can act on cell surface receptors (such as α1β1 and α2β1 integrins [23] and CD44 [24], and depends on the type and physicochemical properties of the hydrogel) and thereby modulate intracellular signal transduction pathways (such as STAT3 [24]). This figure was created with BioRender, accessed on 1 December 2022 (https://biorender.com/).

Figure 1

General scheme of the essential parameters of hydrogels applied in craniomaxillofacial bone regeneration. Physical and chemical properties, such as stiffness and mesh size, endow hydrogels with the ability to communicate with cells and to transport a variety of cargoes. Furthermore, in order to obtain a better effect of bone repairment, several potential stimulus-responsive systems are listed.

Figure 3

Schematic illustration of a variety of different stimulus-responsive drug delivery system. Stimulus-responsive hydrogels are subjected to specific stimuli, such as light, pH, enzymes, temperature and biochemical conditions, and decompose and deform in response to these stimuli, thereby releasing the cells and drugs. The figure was made with BioRender, accessed on 1 December 2022 (https://biorender.com/).

Figure 4

Hydrogels have been developed via different perspectives of bone repairing. Hydrogels pack different drugs and cells to serve as a scaffold in tissue engineering. The functional groups, forming part of the hydrogels, also contribute to drug loads. Responsive systems can also be applied in promoting the reconstruction of craniomaxillofacial bone defects. This image was drawn using BioRender, accessed on 1 December 2022 (https://biorender.com/).