Osteogenic Growth Peptide Accelerates Bone Healing during Distraction Osteogenesis in Rabbit Tibia

Supramolecular Hydrogel Based on an Osteogenic Growth Peptide Promotes Bone Defect Repair

Current bone defect treatment strategies are associated with several risks and have major limitations. Therefore, it is necessary to develop an inexpensive growth factor delivery system that can be easily produced in large quantities and can promote long-term bone regeneration. An osteogenic growth peptide (OGP) is a 14 amino acid peptide with a short peptide sequence active fragment. In this study, we developed two OGP-based self-assembling supramolecular hydrogels (F- and G-sequence hydrogels) and investigated the in vitro and in vivo effects on proliferation and osteogenesis, including the mechanism of hydrogel-mediated bone defect repair. The hydrogels presented excellent biocompatibility and cell proliferation-promoting properties (1.5-1.7-fold increase). The hydrogels could effectively upregulate the expression of osteogenic factors, including RUNX2, BMP2, OCN, and OPN, to promote osteogenesis differentiation. Interestingly, 353 differentially expressed genes were identified in hBMSCs treated with hydrogels. The hydrogels were proved to be involved in the inflammatory pathways and folate-related pathways to mediate the osteogenesis differentiation. Furthermore, the therapeutic efficiency (bone volume/total volume, trabecular number, and bone mineral density) of hydrogels on bone regeneration in vivo was evaluated. The results showed that the hydrogels promoted bone formation in the early stage of bone defect healing. Taken together, this study was the first to develop and evaluate the properties of OGP-based self-assembling supramolecular hydrogels. Our study will provide inspiration for the development of delivering OGP for bone regeneration.

Recent advances in design and applications of biomimetic self-assembled peptide hydrogels for hard tissue regeneration

Abstract

The development of natural biomaterials applied for hard tissue repair and regeneration is of great importance, especially in societies with a large elderly population. Self-assembled peptide hydrogels are a new generation of biomaterials that provide excellent biocompatibility, tunable mechanical stability, injectability, trigger capability, lack of immunogenic reactions, and the ability to load cells and active pharmaceutical agents for tissue regeneration. Peptide-based hydrogels are ideal templates for the deposition of hydroxyapatite crystals, which can mimic the extracellular matrix. Thus, peptide-based hydrogels enhance hard tissue repair and regeneration compared to conventional methods. This review presents three major self-assembled peptide hydrogels with potential application for bone and dental tissue regeneration, including ionic self-complementary peptides, amphiphilic (surfactant-like) peptides, and triple-helix (collagen-like) peptides. Special attention is given to the main bioactive peptides, the role and importance of self-assembled peptide hydrogels, and a brief overview on molecular simulation of self-assembled peptide hydrogels applied for bone and dental tissue engineering and regeneration.

Graphic abstract

Overview of methods for enhancing bone regeneration in distraction osteogenesis: Potential roles of biometals

BACKGROUND

Distraction osteogenesis (DO) is a functional tissue engineering approach that applies gradual mechanical traction on the bone tissues after osteotomy to stimulate bone regeneration. However, DO still has disadvantages that limit its clinical use, including long treatment duration.

METHODS

Review the current methods of promoting bone formation and consolidation in DO with particular interest on biometal.

RESULTS

Numerous approaches, including physical therapy, gene therapy, growth factor-based therapy, stem-cell-based therapy, and improved distraction devices, have been explored to reduce the DO treatment duration with some success. Nevertheless, no approach to date is widely accepted in clinical practice due to various reasons, such as high expense, short biologic half-life, and lack of effective delivery methods. Biometals, including calcium (Ca), magnesium (Mg), zinc (Zn), copper (Cu), manganese (Mn), and cobalt (Co) have attracted attention in bone regeneration attributed to their biodegradability and bioactive components released during in vivo degradation.

CONCLUSION

This review summarizes the current therapies accelerating bone formation in DO and the beneficial role of biometals in bone regeneration, particularly focusing on the use of biometal Mg and its alloy in promoting bone formation in DO. Translational potential: The potential clinical applications using Mg-based devices to accelerate DO are promising. Mg stimulates expression of multiple intrinsic biological factors and the development of Mg as an implantable component in DO may be used to argument bone formation and consolidation in DO.

Gelatin Templated Polypeptide Co-Cross-Linked Hydrogel for Bone Regeneration

Polypeptides with short chains of amino acid monomers have been widely applied in the clinic because of their various biological functions. However, the easily-inactivated characteristics and burst releasing of the peptides limit their application in vivo. Here, a novel osteogenic polypeptide hydrogel (GelMA-c-OGP) is created by co-cross-linking template photo-cross-linked gelatin (GelMA) with photo-cross-linkable osteogenic growth peptides (OGP) using ultraviolet radiation. GelMA enables the formation of hydrogel with photo-cross-linkable OGP with good mechanical properties and also promotes bone regeneration. GelMA-c-OGP hydrogel accelerates the bone formation procedure of osteogenic precursor cells by significantly enhancing the expression of osteogenic-related genes BMP-2, OCN, and OPN, and increasing the precipitation of calcium salts in osteoblasts. Similarly, GelMA-c-OGP hydrogel promotes bone regeneration in vivo. Furthermore, it is observed that more collagen fibers connect cortical bones in the GelMA-c-OGP implanted group than the control group by hematoxylin-eosin and immunohistochemical staining of Collagen I and TGF-β. The co-cross-linked OGP polypeptide converts from liquid to solid hydrogel with transient UV light in situ, which also can strengthen the mechanical property of the defect bone and avoid burst osteogenic peptide, releasing during the bone defect healing period. Overall, this hydrogel delivering system has a significant impact on bone defect healing compared with traditional methods.

Nonunion fractures, mesenchymal stem cells and bone tissue engineering

Depending on the duration of healing process, 5-10% of bone fractures may result in either nonunion or delayed union. Because nonunions remain a clinically important problem, there is interest in the utilization of tissue engineering strategies to augment bone fracture repair. Three basic biologic elements that are required for bone regeneration include cells, extracellular matrix scaffolds and biological adjuvants for growth, differentiation and angiogenesis. Mesenchymal stem cells (MSCs) are capable to differentiate into various types of the cells including chondrocytes, myoblasts, osteoblasts, and adipocytes. Due to their potential for multilineage differentiation, MSCs are considered important contributors in bone tissue engineering research. In this review we highlight the progress in the application of biomaterials, stem cells and tissue engineering in promoting nonunion bone fracture healing. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A:2551-2561, 2018.

Bone health-promoting bioactive peptides

Bioactive peptides, derivatives of proteins, show versatile biological effects and represent potential health-promoting agents as functional food ingredients and/or nutraceuticals. Bone health depends on the balance between bone formation and resorption. When the balance is disrupted, bone diseases such as osteoporosis and fragility fractures may result. Accumulating evidence suggests that peptides derived from endogenous proteins and food proteins enhance bone health. This article reviews the literature on peptides exhibiting bone health-promoting effects. Possible biochemical mechanisms and production of these peptides are briefly discussed. PRACTICAL APPLICATIONS: Bioactive peptides are derived from food proteins via enzymatic hydrolysis, are already commercially available. In vitro and in vivo bone health-promoting effects of bioactive peptides have been shown in several animal models of osteoporosis and fractures. Thus, peptides can be used as functional food ingredients and/or nutraceuticals. However, their exact role and safety in human subjects should be evaluated prior to commercialization.

The use of bioactive peptides to modify materials for bone tissue repair

It has been well recognized that the modification of biomaterials with appropriate bioactive peptides could further enhance their functions. Especially, it has been shown that peptide-modified bone repair materials could promote new bone formation more efficiently compared with conventional ones. The purpose of this article is to give a general review of recent studies on bioactive peptide-modified materials for bone tissue repair. Firstly, the main peptides for inducing bone regeneration and commonly used methods to prepare peptide-modified bone repair materials are introduced. Then, current in vitro and in vivo research progress of peptide-modified composites used as potential bone repair materials are reviewed and discussed. Generally speaking, the recent related studies have fully suggested that the modification of bone repair materials with osteogenic-related peptides provide promising strategies for the development of bioactive materials and substrates for enhanced bone regeneration and the therapy of bone tissue diseases. Furthermore, we have proposed some research trends in the conclusion and perspectives part.

Role of Osteogenic Growth Peptide (OGP) and OGP(10-14) in Bone Regeneration: A Review

Bone regeneration is a process that involves several molecular mediators, such as growth factors, which directly affect the proliferation, migration and differentiation of bone-related cells. The osteogenic growth peptide (OGP) and its C-terminal pentapeptide OGP(10–14) have been shown to stimulate the proliferation, differentiation, alkaline phosphatase activity and matrix mineralization of osteoblastic lineage cells. However, the exact molecular mechanisms that promote osteoblastic proliferation and differentiation are not completely understood. This review presents the main chemical characteristics of OGP and/or OGP(10–14), and also discusses the potential molecular pathways induced by these growth factors to promote proliferation and differentiation of osteoblasts. Furthermore, since these peptides have been extensively investigated for bone tissue engineering, the clinical applications of these peptides for bone regeneration are discussed.

Improved Cell Adhesion and Osteogenesis of op-HA/PLGA Composite by Poly(dopamine)-Assisted Immobilization of Collagen Mimetic Peptide and Osteogenic Growth Peptide

A nanocomposite of poly(lactide-co-glycolide) (PLGA) and hydroxyapatite (HA) with a different grafting ratio of l-lactic acid oligomer (op-HA) showed better interface compatibility, mineralization, and osteogenetic abilities. However, surface modification of the composite is crucial to improve the osteointegration for bone regeneration. In this study, a biomimetic process via poly(dopamine) coating was utilized to prepare functional substrate surfaces with immobilized bioactive peptides that efficiently regulate the osteogenic differentiation of preosteoblasts (MC3T3-E1). Our study demonstrated that incorporation of collagen mimetic peptide significantly enhanced cell adhesion and proliferation. The immobilization of osteogenic growth peptide induced the osteodifferentiation of cells, as indicated by the alkaline phosphate activity test, quantitative real-time polymerase chain reaction analysis, and immunofluorescence staining. The mineralization on the peptide-modified substrates was also enhanced greatly. Findings from this study revealed that this biofunctionalized layer on op-HA/PLGA substrate improved mineralization and osteogenic differentiation. In conclusion, the surface modification strategy with bioactive peptides shows potential to enhance the osteointegration of bone implants.

Screening of Osteogenic-Enhancing Short Peptides from BMPs for Biomimetic Material Applications

Bone regeneration is an important issue in many situations, such as bone fracture and surgery. Umbilical cord mesenchymal stem cells (UC-MSCs) are promising cell sources for bone regeneration. Bone morphogenetic proteins and their bioactive peptides are biomolecules known to enhance the osteogenic differentiation of MSCs. However, fibrosis can arise during the development of implantable biomaterials. Therefore, it is important to control cell organization by enhancing osteogenic proliferation and differentiation and inhibiting fibroblast proliferation. Thus, we focused on the screening of such osteogenic-enhancing peptides. In the present study, we developed new peptide array screening platforms to evaluate cell proliferation and alkaline phosphatase activity in osteoblasts, UC-MSCs and fibroblasts. The conditions for the screening platform were first defined using UC-MSCs and an osteogenic differentiation peptide known as W9. Next, in silico screening to define the candidate peptides was carried out to evaluate the homology of 19 bone morphogenetic proteins. Twenty-five candidate 9-mer peptides were selected for screening. Finally, the screening of osteogenic-enhancing (osteogenic cell-selective proliferation and osteogenic differentiation) short peptide was carried out using the peptide array method, and three osteogenic-enhancing peptides were identified, confirming the validity of this screening.

The role of peptides in bone healing and regeneration: a systematic review

BACKGROUND

Bone tissue engineering and the research surrounding peptides has expanded significantly over the last few decades. Several peptides have been shown to support and stimulate the bone healing response and have been proposed as therapeutic vehicles for clinical use. The aim of this comprehensive review is to present the clinical and experimental studies analysing the potential role of peptides for bone healing and bone regeneration.

METHODS

A systematic review according to PRISMA guidelines was conducted. Articles presenting peptides capable of exerting an upregulatory effect on osteoprogenitor cells and bone healing were included in the study.

RESULTS

Based on the available literature, a significant amount of experimental in vitro and in vivo evidence exists. Several peptides were found to upregulate the bone healing response in experimental models and could act as potential candidates for future clinical applications. However, from the available peptides that reached the level of clinical trials, the presented results are limited.

CONCLUSION

Further research is desirable to shed more light into the processes governing the osteoprogenitor cellular responses. With further advances in the field of biomimetic materials and scaffolds, new treatment modalities for bone repair will emerge.

A New Way to Accelerate the Distraction of the Transpalatal Suture in Growing Dogs Using Recombinant Human Bone Morphogenetic Protein-2

OBJECTIVE

The purpose of this study was to evaluate the administration of recombinant human bone morphogenetic protein-2 (rhBMP-2) on trans-sutural distraction osteogenesis (TSDO) of the transverse palatal suture in growing dogs.

STUDY DESIGN

A total of 36 growing dogs were used in this study. The experimental animals were treated with different elastic force and rhBMP-2. The bone regeneration was determined with X-ray, histology, and clinical evaluation. The computed values underwent statistical analyses using analysis of variance.

RESULTS

The maxillary complex was most noticeably advanced with an applied elastic force of 600 g (22.4 ± 5.0 mm) and 800 g + rhBMP-2 (24 ± 5.1 mm). Immunohistochemical staining showed that the expression of bone morphogenetic protein-2 and bone morphogenetic protein-4 varied with different elastic force. These changes were statistically significant when 600 g and 800 g + rhBMP-2 were applied within 2 weeks of distraction when compared with controls (P < .05).

CONCLUSIONS

The results of this study suggest that TSDO in the growing dog should be safe and well tolerated when inducing bony lengthening of the maxilla. rhBMP-2 plays an important role in bone regeneration using TSDO.

Nanostructured materials based on mesoporous silica and mesoporous silica/apatite as osteogenic growth peptide carriers

The aim of this work was the preparation of inorganic mesoporous materials from silica, calcium phosphate and a nonionic surfactant and to evaluate the incorporation and release of different concentrations of osteogenic growth peptide (OGP) for application in bone regeneration. The adsorption and release of the labeled peptide with 5,6-carboxyfluorescein (OGP-CF) from the mesoporous matrix was monitored by fluorescence spectroscopy. The specific surface area was 880 and 484 m(2) g(-1) for pure silica (SiO) and silica/apatite (SiCaP), respectively; the area influenced the percentage of incorporation of the peptide. The release of OGP-CF from the materials in simulated body fluid (SBF) was dependent on the composition of the particles, the amount of incorporated peptide and the degradation of the material. The release of 50% of the peptide content occurred at around 4 and 30 h for SiCaP and SiO, respectively. In conclusion, the materials based on SiO and SiCaP showed in vitro bioactivity and degradation; thus, these materials should be considered as alternative biomaterials for bone regeneration.

Transsutural distraction and tissue regeneration of the midfacial skeleton: experimental studies in growing dogs

Objective : The purpose of this study was to evaluate the effect of different mechanical forces on the expansion of the palatine suture using transsutural distraction osteogenesis. Methods : A total of 48 dogs were used in this study. The experimental groups were treated with a custom-designed internal distractor. Bone regeneration was determined with x-rays and histology. The computed values underwent statistical analyses using analysis of variance. Results : The maxillary complex was most noticeably advanced with an applied mechanical force of 600 g (20.15 ± 1.36 mm), compared with forces of 400 g (19.88 ± 1.41 mm) and 800 g (2.24 ± 0.93 mm). Immunohistochemical staining showed that the expression of bone morphogenetic protein-2 and bone morphogenetic protein-4 fluctuated with different mechanical forces. These changes were statistically significant when 600 g of force was applied within 30 days of distraction (P < .05). Conclusions : Transsutural distraction osteogenesis in the growing dog should be safe and well tolerated in inducing bony lengthening of the maxilla, and the optimal force is 600 × g. Bone morphogenetic protein-2 and bone morphogenetic protein-4 may play an important roles in the signaling pathways that link mechanical forces and biological responses.