Osteogenic growth peptide incorporated into PLGA scaffolds accelerates healing of segmental long bone defects in rabbits

Peptide-Based Biomaterials for Bone and Cartilage Regeneration

The healing of osteochondral defects (OCDs) that result from injury, osteochondritis, or osteoarthritis and bear lesions in the cartilage and bone, pain, and loss of joint function in middle- and old-age individuals presents challenges to clinical practitioners because of non-regenerative cartilage and the limitations of current therapies. Bioactive peptide-based osteochondral (OC) tissue regeneration is becoming more popular because it does not have the immunogenicity, misfolding, or denaturation problems associated with original proteins. Periodically, reviews are published on the regeneration of bone and cartilage separately; however, none of them addressed the simultaneous healing of these tissues in the complicated heterogeneous environment of the osteochondral (OC) interface. As regulators of cell adhesion, proliferation, differentiation, angiogenesis, immunomodulation, and antibacterial activity, potential therapeutic strategies for OCDs utilizing bone and cartilage-specific peptides should be examined and investigated. The main goal of this review was to study how they contribute to the healing of OCDs, either alone or in conjunction with other peptides and biomaterials.

Construction of a biocompatible MWCNTs-chitosan composite interface and its application to impedance cytosensing of osteoblastic MC3T3-E1 cells

In this work a carboxylated MWCNTs-chitosan composite sol-gel material was developed via one-step electrodeposition on a glassy carbon electrode as the cytosensing interface of a novel impedance cytosensor. SEM verified the formation of a three-dimensional hierarchical and porous microstructure favorable for the adhesion and spreading of osteoblastic MC3T3-E1 cells. By correlating impedance measurements with fluorescence microscopic characterization results, the cytosensor was demonstrated to have the ability to determine the MC3T3-E1 cell concentration ranging from 5 × 103 to 5 × 108 cell per mL with a detection limit of 1.8 × 103 cell per mL. The impedance cytosensor also enabled monitoring of the cell behavior regarding the processes of cell attachment, spreading, and proliferation in a label-free and quantitative manner. By taking advantage of this cytosensing method, investigating the effect of the C-terminal pentapeptide of osteogenic growth peptide (OGP(10-14)) on MC3T3-E1 cells was accomplished, demonstrating the potential for the application of OGP(10-14) in bone repair and regeneration. Therefore, this work afforded a convenient impedimetric strategy for osteoblastic cell counting and response monitoring that would be useful in evaluating the interactions between osteoblastic cells and specified drugs.

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.

Osteogenic growth peptide (OGP)-loaded amphiphilic peptide (NapFFY) supramolecular hydrogel promotes osteogenesis and bone tissue reconstruction

Efficient bone reconstruction after bone injury remains a great challenge. Injectable supramolecular hydrogels based on amphiphilic peptide have been widely used due to their good biocompatability, non-immunogenicity, and manipulable physicochemical properties by sequence design. Herein, we used a well-studied hydrogelator, NapFFY, to coassemble with osteogenic growth peptide (OGP) to prepare a supramolecular hydrogel, NapFFY-OGP. Both in vitro and in vivo studies demonstrate that OGP was ideally synchronously, and continuously released from the hydrogel to effectively promote the regeneration and reconstruction of skull bone defects. More specifically, after the embedding the rat skull defect area with NapFFY-OGP hydrogels, a bone regeneration rate of 37.54% bone volume fraction (BV/TV) was achieved compared to that of NapFFY hydrogel group (25.09%). NapFFY-OGP hydrogel shows great promise in the clinic repair of bone defects in the future.

Electrospun PLGA Fiber Diameter and Alignment of Tendon Biomimetic Fleece Potentiate Tenogenic Differentiation and Immunomodulatory Function of Amniotic Epithelial Stem Cells

Injured tendons are challenging in their regeneration; thus, tissue engineering represents a promising solution. This research tests the hypothesis that the response of amniotic epithelial stem cells (AECs) can be modulated by fiber diameter size of tendon biomimetic fleeces. Particularly, the effect of electrospun poly(lactide-co-glycolide) (PLGA) fleeces with highly aligned microfibers possessing two different diameter sizes (1.27 and 2.5 µm: ha1- and ha2-PLGA, respectively) was tested on the ability of AECs to differentiate towards the tenogenic lineage by analyzing tendon related markers (Collagen type I: COL1 protein and mRNA Scleraxis: SCX, Tenomodulin: TNMD and COL1 gene expressions) and to modulate their immunomodulatory properties by investigating the pro- (IL-6 and IL-12) and anti- (IL-4 and IL-10) inflammatory cytokines. It was observed that fiber alignment and not fiber size influenced cell morphology determining the morphological change of AECs from cuboidal to fusiform tenocyte-like shape. Instead, fleece mechanical properties, cell proliferation, tenogenic differentiation, and immunomodulation were regulated by changing the ha-PLGA microfiber diameter size. Specifically, higher DNA quantity and better penetration within the fleece were found on ha2-PLGA, while ha1-PLGA fleeces with small fiber diameter size had better mechanical features and were more effective on AECs trans-differentiation towards the tenogenic lineage by significantly translating more efficiently SCX into the downstream effector TNMD. Moreover, the fiber diameter of 1.27 µm induced higher expression of pro-regenerative, anti-inflammatory interleukins mRNA expression (IL-4 and IL-10) with favorable IL-12/IL-10 ratio with respect to the fiber diameter of 2.5 µm. The obtained results demonstrate that fiber diameter is a key factor to be considered when designing tendon biomimetic fleece for tissue repair and provide new insights into the importance of controlling matrix parameters in enhancing cell differentiation and immunomodulation either for the cells functionalized within or for the transplanted host tissue.

Calcium Phosphate Spacers for the Local Delivery of Sitafloxacin and Rifampin to Treat Orthopedic Infections: Efficacy and Proof of Concept in a Mouse Model of Single-Stage Revision of Device-Associated Osteomyelitis

Osteomyelitis is a chronic bone infection that is often treated with adjuvant antibiotic-impregnated poly(methyl methacrylate) (PMMA) cement spacers in multi-staged revisions. However, failure rates remain substantial due to recurrence of infection, which is attributed to the poor performance of the PMMA cement as a drug release device. Hence, the objective of this study was to design and evaluate a bioresorbable calcium phosphate scaffold (CaPS) for sustained antimicrobial drug release and investigate its efficacy in a murine model of femoral implant-associated osteomyelitis. Incorporating rifampin and sitafloxacin, which are effective against bacterial phenotypes responsible for bacterial persistence, into 3D-printed CaPS coated with poly(lactic co-glycolic) acid, achieved controlled release for up to two weeks. Implantation into the murine infection model resulted in decreased bacterial colonization rates at 3- and 10-weeks post-revision for the 3D printed CaPS in comparison to gentamicin-laden PMMA. Furthermore, a significant increase in bone formation was observed for 3D printed CaPS incorporated with rifampin at 3 and 10 weeks. The results of this study demonstrate that osteoconductive 3D printed CaPS incorporated with antimicrobials demonstrate more efficacious bacterial colonization outcomes and bone growth in a single-stage revision in comparison to gentamicin-laden PMMA requiring a two-stage revision.

Current advances for bone regeneration based on tissue engineering strategies

Bone tissue engineering (BTE) is a rapidly developing strategy for repairing critical-sized bone defects to address the unmet need for bone augmentation and skeletal repair. Effective therapies for bone regeneration primarily require the coordinated combination of innovative scaffolds, seed cells, and biological factors. However, current techniques in bone tissue engineering have not yet reached valid translation into clinical applications because of several limitations, such as weaker osteogenic differentiation, inadequate vascularization of scaffolds, and inefficient growth factor delivery. Therefore, further standardized protocols and innovative measures are required to overcome these shortcomings and facilitate the clinical application of these techniques to enhance bone regeneration. Given the deficiency of comprehensive studies in the development in BTE, our review systematically introduces the new types of biomimetic and bifunctional scaffolds. We describe the cell sources, biology of seed cells, growth factors, vascular development, and the interactions of relevant molecules. Furthermore, we discuss the challenges and perspectives that may propel the direction of future clinical delivery in bone regeneration.

Biopolymer-based membranes associated with osteogenic growth peptide for guided bone regeneration

Barrier membranes for guided bone regeneration (GBR) mainly promote mechanical maintenance of bone defect space and induce osteopromotion. Additionally, biopolymer-based membranes may provide greater bioactivity and biocompatibility due to their similarity to extracellular matrix (ECM). In this study, biopolymers-based membranes from bacterial cellulose (BC) and collagen (COL) associated with osteogenic growth peptide (OGP(10-14)) were evaluated to determine in vitro osteoinductive potential in early osteogenesis; moreover, histological study was performed to evaluate the BC-COL OGP(10-14) membranes on bone healing after GBR in noncritical defects in rat femur. The results showed that the BC-COL and BC-COL OGP(10-14) membranes promoted cell proliferation and alkaline phosphatase activity in osteoblastic cell cultures. However, ECM mineralization was similar between cultures grown on BC OGP(10-14) and BC-COL OGP(10-14) membranes. In vivo results showed that all the membranes tested, including the peptide-free BC membrane, promoted better bone regeneration than control group. Furthermore, the BC-COL OGP(10-14) membranes induced higher radiographic density in the repaired bone than the other groups at 1, 4 and 16 weeks. Histomorphometric analyses revealed that the BC-COL OGP(10-14) induced higher percentage of bone tissue in the repaired area at 2 and 4 weeks than others membranes. In general, these biopolymer-based membranes might be potential candidates for bone regeneration applications.

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.

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.

Functionalization of biomaterials with small osteoinductive moieties

Human mesenchymal stem cells (MSCs) are currently recognized as a powerful cell source for regenerative medicine, notably for their capacity to differentiate into multiple cell types. The combination of MSCs with biomaterials functionalized with instructive cues can be used as a strategy to direct specific lineage commitment, and can thus improve the therapeutic efficacy of these cells. In terms of biomaterial design, one common approach is the functionalization of materials with ligands capable of directly binding to cell receptors and trigger specific differentiation signaling pathways. Other strategies focus on the use of moieties that have an indirect effect, acting, for example, as sequesters of bioactive ligands present in the extracellular milieu that, in turn, will interact with cells. Compared with complex biomolecules, the use of simple compounds, such as chemical moieties and peptides, and other small molecules can be advantageous by leading to less expensive and easily tunable biomaterial formulations. This review describes different strategies that have been used to promote substrate-mediated guidance of osteogenic differentiation of immature osteoblasts, osteoprogenitors and MSCs, through chemically conjugated small moieties, both in two- and three-dimensional set-ups. In each case, the selected moiety, the coupling strategy and the main findings of the study were highlighted. The latest advances and future perspectives in the field are also discussed.

Resorbable, amino acid-based poly(ester urea)s crosslinked with osteogenic growth peptide with enhanced mechanical properties and bioactivity

Materials currently used for the treatment of bone defects include ceramics, polymeric scaffolds and composites, which are often impregnated with recombinant growth factors and other bioactive substances. While these materials have seen instances of success, each has inherent shortcomings including prohibitive expense, poor protein stability, poorly defined growth factor release and less than desirable mechanical properties. We have developed a novel class of amino acid-based poly(ester urea)s (PEU) materials which are biodegradable in vivo and possess mechanical properties superior to conventionally used polyesters (<3.5 GPa) available currently to clinicians and medical providers. We report the use of a short peptide derived from osteogenic growth peptide (OGP) as a covalent crosslinker for the PEU materials. In addition to imparting specific bioactive signaling, our crosslinking studies show that the mechanical properties increase proportionally when 0.5% and 1.0% concentrations of the OGP crosslinker are added. Our results in vitro and in an in vivo subcutaneous rat model show the OGP-based crosslinkers, which are small fragments of growth factors that are normally soluble, exhibit enhanced proliferative activity, accelerated degradation properties and concentration dependent bioactivity when immobilized.

Poly(lactide-co-glycolide) porous scaffolds for tissue engineering and regenerative medicine

Porous scaffolds fabricated from biocompatible and biodegradable polymers play vital roles in tissue engineering and regenerative medicine. Among various scaffold matrix materials, poly(lactide-co-glycolide) (PLGA) is a very popular and an important biodegradable polyester owing to its tunable degradation rates, good mechanical properties and processibility, etc. This review highlights the progress on PLGA scaffolds. In the latest decade, some facile fabrication approaches at room temperature were put forward; more appropriate pore structures were designed and achieved; the mechanical properties were investigated both for dry and wet scaffolds; a long time biodegradation of the PLGA scaffold was observed and a three-stage model was established; even the effects of pore size and porosity on in vitro biodegradation were revealed; the PLGA scaffolds have also been implanted into animals, and some tissues have been regenerated in vivo after loading cells including stem cells.

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

Distraction osteogenesis is a valuable treatment method that allows limb lengthening or reconstruction of large bone defects. However, its major disadvantage is the long period required for the consolidation of a distraction callus. Osteogenic growth peptide (OGP) stimulates endochondral bone formation in fracture callus, but its capacity to promote regenerate ossification during distraction osteogenesis has not been evaluated. This study investigated whether intravenously administered OGP accelerated bone healing during distraction osteogenesis in 36 male New Zealand White rabbits, randomized into two groups. The treatment group received OGP (200 ng/kg body weight) in phosphate-buffered saline (PBS), intravenously, each day; the control group received PBS alone. A 15-mm lengthening of the right lower leg was performed using the method of Ilizarov. Evidence from biomechanical, histological and radiographic evaluations demonstrated that systemic OGP treatment promoted optimal new bone formation during distraction osteogenesis in this rabbit model.