Controlled release of basic fibroblast growth factor from a peptide biomaterial for bone regeneration

The Expression Level of Inflammation-Related Genes in Patients With Bone Nonunion and the Effect of BMP-2 Infected Mesenchymal Stem Cells Combined With nHA/PA66 on the Inflammation Level of Femoral Bone Nonunion Rats

Bone nonunion delays fracture end repair and is associated with inflammation. Although bone nonunion can be effectively repaired in clinical practice, many cases of failure. Studies have confirmed that BMP-2 and nHA/PA66 repaired bone defects successfully. There are few studies on the effects of the combined application of BMP-2 and NHA/PA66 on bone nonunion osteogenesis and inflammation. We aimed to investigate the expression level of inflammation-related genes in patients with bone nonunion and the effect of BMP-2-infected mesenchymal stem cells combined with nHA/PA66 on the level of inflammation in femur nonunion rats. We searched for a gene expression profile related to bone nonunion inflammation (GSE93138) in the GEO public database. Bone marrow mesenchymal stem cells (MSCs) of SD rats were cultured and passed through. We infected the third generation of MSCs with lentivirus carrying BMP-2 and induced the infected MSCs to bone orientation. We detected the expression level of BMP-2 by RT-PCR and the cell viability and alkaline phosphatase (ALP) activity by CCK8 and then analyzed the cell adhesion ability. Finally, the levels of related inflammatory factors, including C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and Erythrocyte Sedimentation Rate (ESR), were detected in nonunion rats. Our findings: The patients with nonunion had up-regulated expression of 26 differentially inflammatory genes. These genes are mainly enriched in innate immune response, extracellular region, calcium ion binding, Pantothenate and CoA biosynthesis pathways. The expression level of BMP-2 in the Lenti-BMP-2 group was higher (vs. empty lentivirus vector group: t=5.699; vs. uninfected group t=3.996). The cell activity of the MSCs + BMP-2 + nHA/PA66 group increased gradually. After being combined with nHA/PA66, MSCs transfected with BMP-2 spread all over the surface of nHA/PA66 and grew into the material pores. MSCs + BMP-2 + nHA/PA66 cells showed positive ALP staining, and the OD value of ALP was the highest. The levels of CRP, IL-6, TNF-alpha, and ESR in the MSCs + BMP-2 + nHA/PA66 group were lower than those in the MSCs and MSCs + nHA/PA66 group but higher than those in MSCs + BMP-2 group. The above comparisons were all P<0.05. The findings demonstrated that the expression level of inflammation-related genes increased in the patients with bone nonunion. The infection of MSCs by BMP-2 could promote the directed differentiation of MSCs into osteoblasts in the bone marrow of rats, enhance the cell adhesion ability and ALP activity, and reduce inflammation in rats with bone nonunion.

Preparation and Characterization of Carboxymethyl Chitosan/Sodium Alginate Composite Hydrogel Scaffolds Carrying Chlorhexidine and Strontium-Doped Hydroxyapatite

Herein, we introduce a novel composite hydrogel scaffold designed for addressing infectious jaw defects, a significant challenge in clinical settings caused by the inherent limited self-regenerative capacity of bone tissues. The scaffold was engineered from a blend of carboxymethyl chitosan (CMCS)/sodium alginate (SA) hydrogel (CSH), β-cyclodextrin/chlorhexidine clathrate (β-CD-CHX), and strontium-nanohydroxyapatite nanoparticles (Sr-nHA). The β-CD-CHX and Sr-nHA components were synthesized using a saturated aqueous solution and a coprecipitation method, respectively. Subsequently, these elements were encapsulated within the CSH matrix. Comprehensive characterization of the CMCS/SA/β-CD-CHX/Sr-nHA composite hydrogel scaffold via scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy validated the successful synthesis. The swelling and in vitro degradation behaviors proved that the composite hydrogel had good physical properties, while in vitro evaluations demonstrated favorable biocompatibility and osteoinductive properties. Additionally, antibacterial assessments revealed its effectiveness against common pathogens, Staphylococcus aureus and Escherichia coli. Overall, our results indicate that the CMCS/SA/β-CD-CHX/Sr-nHA composite hydrogel scaffolds exhibit significant potential for effectively treating infection-prone jaw defects.

Zinc-energized dynamic hydrogel accelerates bone regeneration via potentiating the coupling of angiogenesis and osteogenesis

Insufficient initial vascularization plays a pivotal role in the ineffectiveness of bone biomaterials for treating bone defects. Consequently, enhancing the angiogenic properties of bone repair biomaterials holds immense importance in augmenting the efficacy of bone regeneration. In this context, we have successfully engineered a composite hydrogel capable of promoting vascularization in the process of bone regeneration. To achieve this, the researchers first prepared an aminated bioactive glass containing zinc ions (AZnBg), and hyaluronic acid contains aldehyde groups (HA-CHO). The composite hydrogel was formed by combining AZnBg with gelatin methacryloyl (GelMA) and HA-CHO through Schiff base bonding. This composite hydrogel has good biocompatibility. In addition, the composite hydrogel exhibited significant osteoinductive activity, promoting the activity of ALP, the formation of calcium nodules, and the expression of osteogenic genes. Notably, the hydrogel also promoted umbilical vein endothelial cell migration as well as tube formation by releasing zinc ions. The results of in vivo study demonstrated that implantation of the composite hydrogel in the bone defect of the distal femur of rats could effectively stimulate bone generation and the development of new blood vessels, thus accelerating the bone healing process. In conclusion, the combining zinc-containing bioactive glass with hydrogels can effectively promote bone growth and angiogenesis, making it a viable option for the repair of critical-sized bone defects.

Research progress of vascularization strategies of tissue-engineered bone

The bone defect caused by fracture, bone tumor, infection, and other causes is not only a problematic point in clinical treatment but also one of the hot issues in current research. The development of bone tissue engineering provides a new way to repair bone defects. Many animal experimental and rising clinical application studies have shown their excellent application prospects. The construction of rapid vascularization of tissue-engineered bone is the main bottleneck and critical factor in repairing bone defects. The rapid establishment of vascular networks early after biomaterial implantation can provide sufficient nutrients and transport metabolites. If the slow formation of the local vascular network results in a lack of blood supply, the osteogenesis process will be delayed or even unable to form new bone. The researchers modified the scaffold material by changing the physical and chemical properties of the scaffold material, loading the growth factor sustained release system, and combining it with trace elements so that it can promote early angiogenesis in the process of induced bone regeneration, which is beneficial to the whole process of bone regeneration. This article reviews the local vascular microenvironment in the process of bone defect repair and the current methods of improving scaffold materials and promoting vascularization.

Self-Assembled Peptide Hydrogels in Regenerative Medicine

Regenerative medicine is a complex discipline that is becoming a hot research topic. Skin, bone, and nerve regeneration dominate current treatments in regenerative medicine. A new type of drug is urgently needed for their treatment due to their high vulnerability to damage and weak self-repairing ability. A self-assembled peptide hydrogel is a good scaffolding material in regenerative medicine because it is similar to the cytoplasmic matrix environment; it promotes cell adhesion, migration, proliferation, and division; and its degradation products are natural and harmless proteins. However, fewer studies have examined the specific mechanisms of self-assembled peptide hydrogels in promoting tissue regeneration. This review summarizes the applications and mechanisms of self-assembled short peptide and peptide hydrogels in skin, bone, and neural healing to improve their applications in tissue healing and regeneration.

Advances in Self-Assembled Peptides as Drug Carriers

In recent years, self-assembled peptide nanotechnology has attracted a great deal of attention for its ability to form various regular and ordered structures with diverse and practical functions. Self-assembled peptides can exist in different environments and are a kind of medical bio-regenerative material with unique structures. These materials have good biocompatibility and controllability and can form nanoparticles, nanofibers and hydrogels to perform specific morphological functions, which are widely used in biomedical and material science fields. In this paper, the properties of self-assembled peptides, their influencing factors and the nanostructures that they form are reviewed, and the applications of self-assembled peptides as drug carriers are highlighted. Finally, the prospects and challenges for developing self-assembled peptide nanomaterials are briefly discussed.

Nano-Hydroxyapatite Composite Scaffolds Loaded with Bioactive Factors and Drugs for Bone Tissue Engineering

Nano-hydroxyapatite (n-HAp) is similar to human bone mineral in structure and biochemistry and is, therefore, widely used as bone biomaterial and a drug carrier. Further, n-HAp composite scaffolds have a great potential role in bone regeneration. Loading bioactive factors and drugs onto n-HAp composites has emerged as a promising strategy for bone defect repair in bone tissue engineering. With local delivery of bioactive agents and drugs, biological materials may be provided with the biological activity they lack to improve bone regeneration. This review summarizes classification of n-HAp composites, application of n-HAp composite scaffolds loaded with bioactive factors and drugs in bone tissue engineering and the drug loading methods of n-HAp composite scaffolds, and the research direction of n-HAp composite scaffolds in the future is prospected.

Effects and metabolism of fish collagen sponge in repairing acute wounds of rat skin

Objective: Study the repair effect of tilapia collagen on acute wounds, and the effect on the expression level of related genes and its metabolic direction in the repair process. Materials and methods: After the full-thickness skin defect model was constructed in standard deviation rats, the wound healing effect was observed and evaluated by means of characterization, histology, and immunohistochemistry. RT-PCR, fluorescence tracer, frozen section and other techniques were used to observe the effect of fish collagen on the expression of related genes and its metabolic direction in the process of wound repair. Results: After implantation, there was no immune rejection reaction, fish collagen fused with new collagen fibers in the early stage of wound repair, and was gradually degraded and replaced by new collagen in the later stage. It has excellent performance in inducing vascular growth, promoting collagen deposition and maturation, and re-epithelialization. The results of fluorescent tracer showed that fish collagen was decomposed, and the decomposition products were involved in the wound repair process and remained at the wound site as a part of the new tissue. RT-PCR results showed that, without affecting collagen deposition, the expression level of collagen-related genes was down-regulated due to the implantation of fish collagen. Conclusion: Fish collagen has good biocompatibility and wound repair ability. It is decomposed and utilized in the process of wound repair to form new tissues.

Supramolecular Peptide Nanofiber Hydrogels for Bone Tissue Engineering: From Multihierarchical Fabrications to Comprehensive Applications

Bone tissue engineering is becoming an ideal strategy to replace autologous bone grafts for surgical bone repair, but the multihierarchical complexity of natural bone is still difficult to emulate due to the lack of suitable biomaterials. Supramolecular peptide nanofiber hydrogels (SPNHs) are emerging biomaterials because of their inherent biocompatibility, satisfied biodegradability, high purity, facile functionalization, and tunable mechanical properties. This review initially focuses on the multihierarchical fabrications by SPNHs to emulate natural bony extracellular matrix. Structurally, supramolecular peptides based on distinctive building blocks can assemble into nanofiber hydrogels, which can be used as nanomorphology-mimetic scaffolds for tissue engineering. Biochemically, bioactive motifs and bioactive factors can be covalently tethered or physically absorbed to SPNHs to endow various functions depending on physiological and pharmacological requirements. Mechanically, four strategies are summarized to optimize the biophysical microenvironment of SPNHs for bone regeneration. Furthermore, comprehensive applications about SPNHs for bone tissue engineering are reviewed. The biomaterials can be directly used in the form of injectable hydrogels or composite nanoscaffolds, or they can be used to construct engineered bone grafts by bioprinting or bioreactors. Finally, continuing challenges and outlook are discussed.

Chirality-induced bionic scaffolds in bone defects repair-a review

Due to lack of amino sugar with aging, people will suffer from various epidemic bone diseases called "undead cancer" by the World Health Organization. The key problem in bone tissue engineering that has not been completely resolved is the repair of critical large-scale bone and cartilage defects. The chirality of the extracellular matrix plays a decisive role in the physiological activity of bone cells and the occurrence of bone tissue, but the mechanism of chirality in regulating cell adhesion and growth is still in the early stage of exploration. This paper reviews the application progress of chirality-induced bionic scaffolds in bone defects repair based on "soft" and "hard" scaffolds. The aim is to summarize the effects of different chiral structures (L-shaped and D-shaped) in the process of inducing bionic scaffolds in bone defects repair. In addition, many technologies and methods as well as issues worthy of special consideration for preparing chirality-induced bionic scaffolds are also introduced. We expect that this work can provide inspiring ideas for designing new chirality-induced bionic scaffolds and promote the development of chirality in bone tissue engineering. This article is protected by copyright. All rights reserved.

Fabrication of In Situ Grown Hydroxyapatite Nanoparticles Modified Porous Polyetheretherketone Matrix Composites to Promote Osteointegration and Enhance Bone Repair

The repairment of critical-sized bone defects is a serious problem that stimulates the development of new biomaterials. In this study, nanohydroxyapatite (nHA)-doped porous polyetheretherketone (pPEEK) were successfully fabricated by the thermally induced phase separation method and hydrothermal treatment. Structural analysis was performed by X-ray diffraction. The water contact angles and scanning electron microscopy were measured to assess physical properties of surfaces. The mechanical strength of the composites is also determined. Microcomputed tomography is used to characterize the nHA content of the composites. The in vitro bioactivity of the composites with or without nHA was investigated by using murine pre-osteoblasts MC3T3-E1, and the results of cytotoxicity and cell proliferation assays revealed that the cytocompatibility of all specimens was good. Adherence assays were employed to examine the adhesion and morphology of cells on different materials. However, nHA-doped composites induced cell attachment and cell spreading more significantly. Osteogenic differentiation was investigated using alkaline phosphatase activity and alizarin red staining, and these in vitro results demonstrated that composites containing nHA particles enhanced osteoblast differentiation. Its effectiveness for promoting osteogenesis was also confirmed in an in vivo animal experiment using a tibial defective rat model. After 8 weeks of implantation, compared to the pure PEEK and pPEEK without nHA groups, the nHA-pPEEK group showed better osteogenic activity. The results indicate that the nHA-pPEEK composites are possibly a well-designed bone substitute for critical-sized bone defects by promoting bone regeneration and osteointegration successfully.

Local dual delivery therapeutic strategies: Using biomaterials for advanced bone tissue regeneration

Bone development is a complex process involving a vast number of growth factors and chemical substances. These factors include transforming growth factor-beta, platelet-derived growth factor, insulin-like growth factor, and most importantly, the bone morphogenetic protein, which exhibits excellent therapeutic value in bone repair. However, the spatial-temporal relationship in the expression of these factors during bone formation makes the bone repair a more complicated process to address. Thus, using a single therapeutic agent to address bone formation does not seem to provide a clinically effective option. Conversely, a dual delivery approach facilitating the co-delivery of agents has proved to be a dynamic alternative since such a strategy can provide more efficient spatial-temporal action. Such delivery systems can smartly target more than one pathway or differentiation lineage and thus offer more efficient bone regeneration. This review discusses various dual delivery strategies reported in the literature employed to achieve improved bone regeneration. These include concurrent use of different therapeutic agents (including growth factors and drugs), enhancing bone formation and cell recruitment, and improving the efficiency of bone healing.

The Role of Growth Factors in Bioactive Coatings

With increasing obesity and an ageing population, health complications are also on the rise, such as the need to replace a joint with an artificial one. In both humans and animals, the integration of the implant is crucial, and bioactive coatings play an important role in bone tissue engineering. Since bone tissue engineering is about designing an implant that maximally mimics natural bone and is accepted by the tissue, the search for optimal materials and therapeutic agents and their concentrations is increasing. The incorporation of growth factors (GFs) in a bioactive coating represents a novel approach in bone tissue engineering, in which osteoinduction is enhanced in order to create the optimal conditions for the bone healing process, which crucially affects implant fixation. For the application of GFs in coatings and their implementation in clinical practice, factors such as the choice of one or more GFs, their concentration, the coating material, the method of incorporation, and the implant material must be considered to achieve the desired controlled release. Therefore, the avoidance of revision surgery also depends on the success of the design of the most appropriate bioactive coating. This overview considers the integration of the most common GFs that have been investigated in in vitro and in vivo studies, as well as in human clinical trials, with the aim of applying them in bioactive coatings. An overview of the main therapeutic agents that can stimulate cells to express the GFs necessary for bone tissue development is also provided. The main objective is to present the advantages and disadvantages of the GFs that have shown promise for inclusion in bioactive coatings according to the results of numerous studies.

Nanohydroxyapatite/polyamide 66 crosslinked with QK and BMP-2-derived peptide prevented femur nonunion in rats

A dual-peptide controlled released system based on nHA/PA66 scaffold for enhancing bone regeneration.

Application of additive manufacturing in customized titanium mandibular implants for patients with oral tumors

The application of additive manufacturing (AM) technology has been widely used in various medical fields, including craniomaxillofacial surgery. The aim of the present study was to examine the surgical efficiency and post-operative outcomes of patient-specific titanium mandibular reconstruction using AM. Major steps in directly designing and manufacturing 3D customized titanium implants are discussed. Furthermore, pre-operative preparations, surgical procedures and post-operative treatment outcomes were compared among patients who received mandibular reconstruction using a customized 3D titanium implant, titanium reconstruction plates or vascularized autologous fibular grafting. Use of a customized titanium implant significantly improved surgical efficiency and precision. When compared with mandibular reconstruction using the two conventional approaches, patients who received the customized implant were significantly more satisfied with their facial appearance, and exhibited minimal post-operative complications in the 12-month follow-up period. Patients who underwent mandibular reconstruction using a customized titanium implant displayed improved mandibular contour symmetry, restored occlusal function, normal range of mouth opening and no temporomandibular joint related pain; all complications frequently experienced by patients who undergo conventional approaches of mandibular reconstruction.

Tooth Formation: Are the Hardest Tissues of Human Body Hard to Regenerate?

With increasing life expectancy, demands for dental tissue and whole-tooth regeneration are becoming more significant. Despite great progress in medicine, including regenerative therapies, the complex structure of dental tissues introduces several challenges to the field of regenerative dentistry. Interdisciplinary efforts from cellular biologists, material scientists, and clinical odontologists are being made to establish strategies and find the solutions for dental tissue regeneration and/or whole-tooth regeneration. In recent years, many significant discoveries were done regarding signaling pathways and factors shaping calcified tissue genesis, including those of tooth. Novel biocompatible scaffolds and polymer-based drug release systems are under development and may soon result in clinically applicable biomaterials with the potential to modulate signaling cascades involved in dental tissue genesis and regeneration. Approaches for whole-tooth regeneration utilizing adult stem cells, induced pluripotent stem cells, or tooth germ cells transplantation are emerging as promising alternatives to overcome existing in vitro tissue generation hurdles. In this interdisciplinary review, most recent advances in cellular signaling guiding dental tissue genesis, novel functionalized scaffolds and drug release material, various odontogenic cell sources, and methods for tooth regeneration are discussed thus providing a multi-faceted, up-to-date, and illustrative overview on the tooth regeneration matter, alongside hints for future directions in the challenging field of regenerative dentistry.