Biomimetic, Stiff, and Adhesive Periosteum with Osteogenic-Angiogenic Coupling Effect for Bone Regeneration

Tough, Flexible, and Bioactive Amphoteric Copolymer-Based Hydrogel for Bone Regeneration without Encapsulation of Seed Cells/Simulating Cues

Bone tissue scaffolds with good bulk or surface osteoconductivity are always pursued by biomaterial scientists. In this paper, we design a tough and flexible amphoteric copolymer-based (AC) hydrogel with bioactive groups for bone regeneration. In detail, our hydrogels are copolymerized with N-acyl glycinamide (NAGA), anionic acrylate alendronate (AcAln), and cationic (2-(acryloyloxy)ethyl) trimethyl ammonium chloride (DMAEA-Q) by free radical polymerization. There are three kinds of synergetic physical cross-links among our polyamphion hydrogels: (1) double hydrogen bonds between amide groups in NAGA to provide toughness, (2) hydrogen bonds between dual bisphosphite groups in AcAln, and (3) weak ionic pairs between the anionic bisphosphite groups and the cationic quaternary ammonium groups in DMAEA-Q to offer flexibility. The AC hydrogel shows osteoid-like viscoelasticity, which makes the AC hydrogel osteogenesis inductive. During the repairing process, the bioactive bisphosphite groups accelerate the calcium fixation to expedite the mineralization of the new-formed bone. At the same time, the surface charge property of AC hydrogels also prevents fibrous cyst formation, thus guaranteeing osseointegration. Our in vitro data strongly demonstrate that the AC hydrogel is an excellent matrix to induce osteogenesis of rat bone marrow mesenchymal stem cells. More importantly, the following in vivo experiments further prove that the AC hydrogel can reach satisfactory bone regeneration without encapsulation of seed cells or application of external simulating cues. These exciting results demonstrate that our AC hydrogel is a promising scaffold for bone regeneration. Our work can also inspire the constituent and structure design of biomaterial scaffolds for tissue regeneration.

Periosteum and development of the tissue-engineered periosteum for guided bone regeneration

Background

Periosteum plays a significant role in bone formation and regeneration by storing progenitor cells, and also acts as a source of local growth factors and a scaffold for recruiting cells and other growth factors. Recently, tissue-engineered periosteum has been studied extensively and shown to be important for osteogenesis and chondrogenesis. Using biomimetic methods for artificial periosteum synthesis, membranous tissues with similar function and structure to native periosteum are produced that significantly improve the efficacy of bone grafting and scaffold engineering, and can serve as direct replacements for native periosteum. Many problems involving bone defects can be solved by preparation of idealized periosteum from materials with different properties using various techniques.

Methods

This review summarizes the significance of periosteum for osteogenesis and chondrogenesis from the aspects of periosteum tissue structure, osteogenesis performance, clinical application, and development of periosteum tissue engineering. The advantages and disadvantages of different tissue engineering methods are also summarized.

Results

The fast-developing field of periosteum tissue engineering is aimed toward synthesis of bionic periosteum that can ensure or accelerate the repair of bone defects. Artificial periosteum materials can be similar to natural periosteum in both structure and function, and have good therapeutic potential. Induction of periosteum tissue regeneration and bone regeneration by biomimetic periosteum is the ideal process for bone repair.

Conclusions

Periosteum is essential for bone formation and regeneration, and it is indispensable in bone repair. Achieving personalized structure and composition in the construction of tissue engineering periosteum is in accordance with the design concept of both universality and emphasis on individual differences and ensures the combination of commonness and individuality, which are expected to meet the clinical needs of bone repair more effectively.

The translational potential of this article

To better understand the role of periosteum in bone repair, clarify the present research situation of periosteum and tissue engineering periosteum, and determine the development and optimization direction of tissue engineering periosteum in the future. It is hoped that periosteum tissue engineering will play a greater role in meeting the clinical needs of bone repair in the future, and makes it possible to achieve optimization of bone tissue therapy.

Self-Bonded Hydrogel Inverse Opal Particles as Sprayed Flexible Patch for Wound Healing

Wound healing is an important issue for regenerative medicine. Attempts in this area tend to develop functional wound patches to promote the healing. Here, we present self-bonded hydrogel inverse opal particles as sprayed flexible patch for wound healing. Such particles were fabricated by infusing drugs-loaded gelatin (GT) and carrageenan (CG) pregel into inverse opal scaffolds, which were composed of biocompatible hyaluronic acid methacryloyl (HAMA) and gelatin methacryloyl (GelMA) with graphene oxide quantum dots (GO QDs) doping. Due to the photothermal conversion capability of GO QDs and temperature reversible phase-changing performance of GT/CG, the hybrid particles could undergo GT/CG liquid transformation under the near-infrared (NIR) irradiation, which made them adhere to each other and finally form a flexible patch. Following by the phase-change of GT/CG hydrogel, the encapsulated drugs were also controllably released from the inverse opal scaffold. As the inverse opal scaffolds of the hybrid particles were maintained, their drug release induced refractive index changes could be detected as visual structural color shifting, which could be utilized to monitor their delivery processes. Based on these features, we have demonstrated that the self-bonded particles, administered in the form of spray, could be applied for wound tissue healing and drug delivery monitoring. These results indicate that the self-bonded hydrogel particles have potential value as a multifunctional patch for clinical applications.

Electrospun Nanofibers for Bone Regeneration: From Biomimetic Composition, Structure to Function

In recent years, a variety of novel materials and processing technologies have been developed to prepare tissue engineering scaffolds for bone defect repair. Among them, nanofibers fabricated via electrospinning technology...

Self-adhesive hydrogels for tissue engineering

Hydrogels consisting of a three-dimensional hydrophilic network of biocompatible polymers have been widely used in tissue engineering. Owing to their tunable mechanical properties, hydrogels have been applied in both hard and soft tissues. However, most hydrogels lack self-adhesive properties that enable integration with surrounding tissues, which may result in suture or low repair efficacy. Self-adhesive hydrogels (SAHs), an emerging class of hydrogels based on a combination of three-dimensional hydrophilic networks and self-adhesive properties, continue to garner increased attention in recent years. SAHs exhibit reliable and suitable adherence to tissues, and easily integrate into tissues to promote repair efficiency. SAHs are designed either by mimicking the adhesion mechanism of natural organisms, such as mussels and sandcastle worms, or by using supramolecular strategies. This review summarizes the design and processing strategies of SAHs, clarifies underlying adhesive mechanisms, and discusses their applications in tissue engineering, as well as future challenges.

Fibers by Electrospinning and Their Emerging Applications in Bone Tissue Engineering

Bone tissue engineering (BTE) is an optimized approach for bone regeneration to overcome the disadvantages of lacking donors. Biocompatibility, biodegradability, simulation of extracellular matrix (ECM), and excellent mechanical properties are essential characteristics of BTE scaffold, sometimes including drug loading capacity. Electrospinning is a simple technique to prepare fibrous scaffolds because of its efficiency, adaptability, and flexible preparation of electrospinning solution. Recent studies about electrospinning in BTE are summarized in this review. First, we summarized various types of polymers used in electrospinning and methods of electrospinning in recent work. Then, we divided them into three parts according to their main role in BTE, (1) ECM simulation, (2) mechanical support, and (3) drug delivery system.

Bio-inspired hydrogel-based bandage with robust adhesive and antibacterial abilities for skin closure

Although conventional suturing techniques are commonly used in assisting wound closure, they do pose limited conduciveness and may lead to secondary injury to wound tissues. Inspired by marine organism mussels, we designed and manufactured a bio-inspired hydrogel-based bandage with tough wet tissue adhesion to substitute traditional surgical suture, accelerate wound healing and avoid infection. Poly(γ-glutamic acid) was modified with 3,4-dihydroxyphenylalanine and glycidyl methacylate, then introduced into the acrylic acid-co-acrylamide hydrogel matrix with robust mechanical properties. The hydrogel bandage showed strong chemical linkage adhesion (70 ± 2.1 kPa), which is 2.8 times that of commercial tissue adhesive fibrin glue (25 ± 2.2 kPa). The hydrogel bandage can not only maintain the self-stability, but is also capable of self-tuning adhesive strength in the range of 14-70 kPa to achieve different adhesion effects by tuning constituent ratio. The bandage has desirable compression properties (0.7 ± 0.11 MPa) and tensile elongation (about 25 times), which ensures its resistance to damages, especially in joint spaces. Secondly, the bandage was endowed with antioxidant and endogenous broad-spectrum antibacterial properties with its catechol structure. Results also demonstrated excellent cell compatibility and blood compatibility, certifying its eligible biological safety profile. In a rat full-thickness cutaneous deficiency model, we can clearly observe that the bandage possesses the ability to promote wound healing (only need 6 days). Above all, this research provides a new strategy for the emergency treatment of liver hemostasis and myocardial repair during disaster rescue.

SUPPLEMENTARY INFORMATION

Experimental details and supporting data are available in the online version of the paper10.1007/s40843-021-1724-8.