Enhanced bone healing of rat tooth sockets after administration of epidermal growth factor (EGF) carried by liposome

Artificial Dermis and Human Recombinant Epidermal Growth Factor Application for the Management of Critical Size Calvarial Defect

Restoration of the 3-dimensional structure of the facial and calvarial skeleton after trauma or ablative oncologic surgeries serves as a framework for soft tissue reconstruction. In the present study, the authors aimed to evaluate the osteogenic effect of artificial dermis and epidermal growth factor treatment in critical-sized calvarial defects, which cannot be healed spontaneously. 8 mm calvarial defects were created in 28 male rats and filled with the artificial dermis, the artificial dermis and growth factor, growth factor or left untreated. Atomic absorption spectrometry was used to determine the amount of calcium, scanning electron microscopy was used to show the bone tissue in 3 dimensions, and immunohistochemistry was used to assess the bone formation and cell density. Histologic evaluation at 6 weeks showed incomplete bone regeneration in all groups. No statistical differences were found between the groups with regard to their scores for the following: inflammation, new bone formation, osteocyte density, resorption of bone at the edges of the defect, or fibrous tissue formation in the defect area. In conclusion, the predictability of bone formation in critical-size defects is not clear. Contrary to popular belief, the combined use of epidermal growth factor with artificial dermis or alone did not enhance the potential for osseous healing.

Novel scaffold platforms for simultaneous induction osteogenesis and angiogenesis in bone tissue engineering: a cutting-edge approach

Despite the recent advances in the development of bone graft substitutes, treatment of critical size bone defects continues to be a significant challenge, especially in the elderly population. A current approach to overcome this challenge involves the creation of bone-mimicking scaffolds that can simultaneously promote osteogenesis and angiogenesis. In this context, incorporating multiple bioactive agents like growth factors, genes, and small molecules into these scaffolds has emerged as a promising strategy. To incorporate such agents, researchers have developed scaffolds incorporating nanoparticles, including nanoparticulate carriers, inorganic nanoparticles, and exosomes. Current paper provides a summary of the latest advancements in using various bioactive agents, drugs, and cells to synergistically promote osteogenesis and angiogenesis in bone-mimetic scaffolds. It also discusses scaffold design properties aimed at maximizing the synergistic effects of osteogenesis and angiogenesis, various innovative fabrication strategies, and ongoing clinical studies.

Tailoring the Microarchitectures of 3D Printed Bone-like Scaffolds for Tissue Engineering Applications

Material extrusion (MEX), commonly referred to as fused deposition modeling (FDM) or fused filament fabrication (FFF), is a versatile and cost-effective technique to fabricate suitable scaffolds for tissue engineering. Driven by a computer-aided design input, specific patterns can be easily collected in an extremely reproducible and repeatable process. Referring to possible skeletal affections, 3D-printed scaffolds can support tissue regeneration of large bone defects with complex geometries, an open major clinical challenge. In this study, polylactic acid scaffolds were printed resembling trabecular bone microarchitecture in order to deal with morphologically biomimetic features to potentially enhance the biological outcome. Three models with different pore sizes (i.e., 500, 600, and 700 µm) were prepared and evaluated by means of micro-computed tomography. The biological assessment was carried out seeding SAOS-2 cells, a bone-like cell model, on the scaffolds, which showed excellent biocompatibility, bioactivity, and osteoinductivity. The model with larger pores, characterized by improved osteoconductive properties and protein adsorption rate, was further investigated as a potential platform for bone-tissue engineering, evaluating the paracrine activity of human mesenchymal stem cells. The reported findings demonstrate that the designed microarchitecture, better mimicking the natural bone extracellular matrix, favors a greater bioactivity and can be thus regarded as an interesting option for bone-tissue engineering.

Biopotentials of Collagen Scaffold Impregnated with Plant-Cell-Derived Epidermal Growth Factor in Defective Bone Healing

The combination of scaffolds with recombinant human epidermal growth factor (rhEGF) protein can enhance defective bone healing via synergistic activation to stimulate cellular growth, differentiation, and survival. We examined the biopotentials of an rhEGF-loaded absorbable collagen scaffold (ACS) using a mouse model of calvarial defects, in which the rhEGF was produced from a plant cell suspension culture system because of several systemic advantages. Here, we showed a successful and large-scale production of plant-cell-derived rhEGF protein (p-rhEGF) by introducing an expression vector that cloned with its cDNA under the control of rice α-amylase 3D promoter into rice calli (Oryza sativa L. cv. Dongjin). Implantation with p-rhEGF (5 μg)-loaded ACSs into critical-sized calvarial defects enhanced new bone formation and the expression of osteoblast-specific markers in the defected regions greater than implantation with ACSs alone did. The potency of p-rhEGF-induced bone healing was comparable with that of Escherichia coli-derived rhEGF protein. The exogenous addition of p-rhEGF increased the proliferation of human periodontal ligament cells and augmented the induction of interleukin 8, bone morphogenetic protein 2, and vascular endothelial growth factor in the cells. Collectively, this study demonstrates the successful and convenient production of p-rhEGF, as well as its potency to enhance ACS-mediated bone regeneration by activating cellular responses that are required for wound healing.

The Delivery and Activation of Growth Factors Using Nanomaterials for Bone Repair

Bone regeneration is a comprehensive process that involves different stages, and various growth factors (GFs) play crucial roles in the entire process. GFs are currently widely used in clinical settings to promote bone repair; however, the direct application of GFs is often limited by their fast degradation and short local residual time. Additionally, GFs are expensive, and their use may carry risks of ectopic osteogenesis and potential tumor formation. Nanomaterials have recently shown great promise in delivering GFs for bone regeneration, as they can protect fragile GFs and control their release. Moreover, functional nanomaterials can directly activate endogenous GFs, modulating the regeneration process. This review provides a summary of the latest advances in using nanomaterials to deliver exogenous GFs and activate endogenous GFs to promote bone regeneration. We also discuss the potential for synergistic applications of nanomaterials and GFs in bone regeneration, along with the challenges and future directions that need to be addressed.

Lotus seedpod-inspired internal vascularized 3D printed scaffold for bone tissue repair

In the field of bone defect repair, 3D printed scaffolds have the characteristics of personalized customization and accurate internal structure. However, how to construct a well-structured vascular network quickly and effectively inside the scaffold is essential for bone repair after transplantation. Herein, inspired by the unique biological structure of "lotus seedpod", hydrogel microspheres encapsulating deferoxamine (DFO) liposomes were prepared through microfluidic technology as "lotus seeds", and skillfully combined with a three-dimensional (3D) printed bioceramic scaffold with biomimetic "lotus" biological structure which can internally grow blood vessels. In this composite scaffold system, DFO was effectively released by 36% in the first 6 h, which was conducive to promote the growth of blood vessels inside the scaffold quickly. In the following 7 days, the release rate of DFO reached 69%, which was fundamental in the formation of blood vessels inside the scaffold as well as osteogenic differentiation of bone mesenchymal stem cells (BMSCs). It was confirmed that the composite scaffold could significantly promote the human umbilical vein endothelial cells (HUVECs) to form the vascular morphology within 6 h in vitro. In vivo, the composite scaffold increased the expression of vascularization and osteogenic related proteins Hif1-α, CD31, OPN, and OCN in the rat femoral defect model, significantly cutting down the time of bone repair. To sum up, this "lotus seedpod" inspired porous bioceramic 3D printed scaffold with internal vascularization functionality has broad application prospects in the future.

Epidermal growth factor or platelet-rich plasma combined with induced membrane technique in the treatment of segmental femur defects: an experimental study

Objective

Extensive bone defects remain a therapeutic challenge necessitating alternative surgical approaches with better outcomes. Can increase the effectiveness of PRP or EGF treatment in surgical treatment of large bone defects with Masquelet technique?

Aim of this study examined potential therapeutic benefits of the Masquelet technique with induced membranes in combination with platelet-rich plasma (PRP) or epidermal growth factor (EGF) in a rat model of segmental femur defect.

Methods

Three groups each consisting of 20 Sprague-Dawley rats were defined as follows: EGF group, PRP group, and control group. A femoral bone defect was created and filled with antibiotic embedded polymethyl methacrylate. Half of the animals in each group were sacrificed at week 6 and the pseudo-membranes formed were analyzed. In the remaining half, the cement was removed and the space was filled with autograft. After another 6 weeks, the structures formed were examined radiologically, histologically, and biochemically.

Results

At week 6, both PRP and EGF groups had significantly higher membrane CD31, TGF-beta, and VEGF levels than controls. At week 12, when compared to controls, PRP and EGF groups had significantly higher membrane CD31 levels and the PRP group had significantly higher membrane TGF levels. Regarding bone tissue levels, PRP and EGF groups had significantly higher VEGF levels and the EGF group had significantly higher BMP levels. In addition, PRP and EGF groups had higher radiological scores than controls. However, the two experimental groups did not differ with respect to any parameter tested in this study.

Conclusion

Both PRP and EGF seem to be associated with histological, biochemical, and radiological improvements in experimental rat model of Masquelet technique, warranting in further clinical studies.

Level of evidence

Level 5

Clinical and Radiological Evaluation of Sinus Membrane Osteogenicity Subsequent to Internal Sinus Lifting and Implant Placement

To evaluate the ability of the maxillary sinus membrane to produce bone after internal sinus lifting and implant placement without adding exogenous bone graft, and to assess the quality of bone that has been produced 6 months postoperatively.In this retrospective study, 10 subjects who underwent maxillary sinus floor lifting and met the inclusion criteria were selected and then subdivided into: Group-A underwent internal sinus elevation and placement of implants without the use of bone graft and Group-B underwent classical internal sinus lifting and placement of bovine bone particles and then placement of the implant as a control group. Radiofrequency analysis (RFA) values for measuring the Implant Stability Quotient (ISQ) of all implants were measured by Osstell device. CBCT was performed involving linear measurements of the site of sinus lifting for both groups.High RFA values demonstrating excellent biomechanical stability were observed in Group-A compared to Group-B at 6 months postoperatively. Group-A showed a median of ISQ value;78 (8), 77(12), 79(3.5) and 77(4.50). Group-A was significantly higher in ISQ values than Group-B, which showed median and interquartile range (IQR) of ISQ value of [51(12.50), 54(14.50), 55(9), and 55(7.50)]. However, the amount of bone available in group B was significantly higher than group A; [3.5 mm (0.75) and 3.8 mm (0.69)].Internal sinus lifting without bone graft has the ability of bone formation by osteogenic potential of the sinus membrane. Nevertheless, the high quality of bone being produced is of high importance for the success of an implant without the need for an exogenous bone graft. The newly formed bone was significantly of a better quality in Group-A. Thus, it is recommended to perform internal sinus lifting, without adding bone graft material and allow the osteogenic potential of the maxillary sinus membrane to produce its own osteogenic cells.

Bone Regeneration Induced by Strontium Folate Loaded Biohybrid Scaffolds

Nowadays, regenerative medicine has paid special attention to research (in vitro and in vivo) related to bone regeneration, specifically in the treatment of bone fractures or skeletal defects, which is rising worldwide and is continually demanding new developments in the use of stem cells, growth factors, membranes and scaffolds based on novel nanomaterials, and their applications in patients by using advanced tools from molecular biology and tissue engineering. Strontium (Sr) is an element that has been investigated in recent years for its participation in the process of remodeling and bone formation. Based on these antecedents, this is a review about the Strontium Folate (SrFO), a recently developed non-protein based bone-promoting agent with interest in medical and pharmaceutical fields due to its improved features in comparison to current therapies for bone diseases.

Epidermal growth factor enhances spinal fusion: Posterolateral lumbar fusion model on rats

Objective

The aim of this study was to investigate the effects of human recombinant epidermal growth factor (EGF) on posterolateral lumbar fusion in a rat model.

Methods

36 male Sprague Dawley rats underwent posterolateral fusion at L4-5 level. They were randomly assigned to 3 groups: 1- Sham control group where no local augmentation was made, 2- Local Hydoxyapatite β-tricalcium phosphate (HA/β-TCP) augmentation group and 3- Local HA/β-TCP + EGF augmentation group. Rats were euthanized at 8 weeks post-surgery. 6 rats from each group were selected for manual palpation examination, micro-computed tomography analysis and histologic analysis; and the rest was used for biomechanical analysis.

Results

Based on manual palpation, there was no fusion in the sham control group. Fusion rate was 33.3% in the HA/β-TCP group and 66.7% in the HA/β-TCP + EGF group (p = 0.085). Micro-CT results revealed that new bone formation was higher in the HA/β-TCP + EGF group (BV/TV: 40% vs. 65%) (p = 0.004). Histologically newly formed bone tissue was more pronounced in the EGF group and compacted and bridging bone spicules were observed. The median maximum bending moment values were 0.51 Nmm (0.42–0.59), 0.73 Nmm (0.49–0.88) and 0.91 Nmm (0.66–1.03) in the sham control, HA/β-TCP and HA/β-TCP + EGF groups, respectively (p = 0.013). The median stiffness values were 1.69 N/mm (1.12–2.18), 1.68 N/mm (1.13–2.74) and 3.10 N/mm (1.66–4.40) as in the previous order (p = 0.087).

Conclusion

This study demonstrates that EGF enhances posterolateral lumbar fusion in the rat model. EGF in combination with ceramic grafts increased the fusion rates. Our findings may provide insights to further studies, investigating EGF's clinical usage as an alternative fusion enhancer.

A new nanoscale transdermal drug delivery system: oil body-linked oleosin-hEGF improves skin regeneration to accelerate wound healing

Background

Epidermal growth factor (EGF) can promote cell proliferation as well as migration, which is feasible in tissue wound healing. Oil bodies have been exploited as an important platform to produce exogenous proteins. The exogenous proteins were expressed in oil bodies from plant seeds. The process can reduce purification steps, thereby significantly reducing the purification cost. Mostly, the diameter of oil body particle ranges between 1.0 and 1.5 µm in the safflower seeds, however, it reduces to 700–1000 nm in the transgenic safflower seeds. The significant reduction of particle size in transgenic seeds is extremely beneficial to skin absorption.

Results

The diameter of oil body in the transgenic safflower seeds was recorded in the range of 700–1000 nm. The smaller particle size improved their skin absorption. The expression level of oleosin-hEGF-hEGF in T3 transgenic seeds was highest at 69.32 mg/g of seeds. The oil body expressing oleosin-hEGF-hEGF had significant proliferative activity on NIH/3T3 cells and improved skin regeneration thereby accelerating wound healing in rats. The wound coverage rate exceeded 98% after treatment for 14 days with oil body expressing oleosin-hEGF-hEGF, while the saline without EGF group and wild type oil body group both showed less than 80%. The neonatal fibroblast and collagen were found to be increased in the safflower oil body expressing oleosin-hEGF-hEGF treatment group. TGF-β1, bFGF and VEGF were noted as important growth factors in the repair of cutaneous wounds. Their expression level increased after 4 and 7 day treatment, but decreased after 14 days. Therefore, it can promote skin regeneration to accelerate wounds healing.

Conclusions

The expression of oleosin-hEGF-hEGF in T3 transgenic seeds was 80.43 ng/μL oil body. It had significant proliferative activity on NIH/3T3 cells and improved skin regeneration to accelerate wound healing in rats. The expression process of TGF-β1, bFGF and VEGF increased at first and then gradually declined.

Electronic supplementary material

The online version of this article (10.1186/s12951-018-0387-5) contains supplementary material, which is available to authorized users.

Liposomal Delivery of Demineralized Dentin Matrix for Dental Tissue Regeneration

Current dental restorations have short longevity, and consequently, there is a need for novel tissue engineering strategies that aim to regenerate the dentin-pulp complex. Dentin matrix contains a myriad of bioactive growth factors and extracellular matrix proteins associated with the recruitment, proliferation, and differentiation of dental pulp progenitor cells. In this study, we show that demineralized dentin matrix (DDM), from noncarious dentine, can be encapsulated into liposomes for delivery to dental tissue to promote regeneration. Liposomes were formulated to encapsulate 0-100 μg/mL DDM, lysed with Triton X, and used in vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1) enzyme-linked immunosorbent assays to quantify release. The encapsulation efficiencies were calculated to be 25.9% and 28.8% (VEGF/TGF-β1) for 50 μg/mL DDM liposomes and 39% and 146.7% (VEGF/TGF-β1) for 100 μg/mL DDM liposomes. All liposome formulations had no cytotoxic effects on a dental pulp stem cell (DPSC) clone, as shown by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltertrazolium bromide), Caspase 3/7 assays, and cell counts. The ability of the liposomes to stimulate DPSC chemotactic recruitment was tested by Boyden chamber chemotaxis assays. Unloaded liposomes alone stimulated significant progenitor cell recruitment, while DDM-loaded liposomes further promoted chemotactic recruitment in a dose-dependent manner. DDM liposomes promoted the upregulation of "osteodentin" markers osteocalcin and RUNX2 (Runt-related transcription factor 2) in DPSCs after 9 days of treatment, determined by real-time quantitative PCR. Furthermore, Alizarin Red S staining showed that unloaded liposomes alone induced biomineralization of DPSCs, and DDM liposomes further increased the amount of mineralization observed. DDM liposomes were more effective than free DDM (10 μg/mL) at activating recruitment and osteogenic differentiation of DPSC, which are key events in the endogenous repair of the dentin-pulp complex. The study has highlighted the therapeutic potential of bioactive DDM liposomes in activating dental tissue repair in vitro, suggesting that liposomal delivery from biomaterials could be a valuable tool for reparative dentistry and hard-tissue engineering applications.

Epidermal growth factor regulates apoptosis and oxidative stress in a rat model of spinal cord injury

Spinal cord injury (SCI) leads to vascular damage and disruption of blood-spinal cord barrier which participates in secondary nerve injury. Epidermal growth factor (EGF) is an endogenous protein which regulates cell proliferation, growth and differention. Previous studies reported that EGF exerts neuroprotective effect in spinal cord after SCI. However, the molecular mechanisms underlying EGF-mediated protection in different regions of nervous system have not shown yet. In this study, we aimed to examine possible anti-apoptotic and protective roles of EGF not only in spinal cord but also in brain following SCI. Twenty-eight adult rats were divided into four groups of seven animals each as follows: sham, trauma (SCI), SCI + EGF and SCI + methylprednisolone (MP) groups. The functional neurological deficits due to the SCI were assessed by behavioral analysis using the Basso, Beattie and Bresnahan (BBB) open-field locomotor test. The alterations in pro-/anti-apoptotic protein levels and antioxidant enzyme activities were measured in spinal cord and frontal cortex. In our study, EGF promoted locomotor recovery and motor neuron survival of SCI rats. EGF treatment significantly decreased Bax and increased Bcl-2 protein expressions both in spinal cord and brain when compared to SCI group. Moreover, antioxidant enzyme activities including catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were increased following EGF treatment similar to MP treatment. Our experiment also suggests that alteration of the ratio of Bcl-2 to Bax may result from decreased apoptosis following EGF treatment. As a conclusion, these results show, for the first time, that administration of EGF exerts its protection via regulating apoptotic and oxidative pathways in response to spinal cord injury in different regions of central nervous system.

Wound healing related agents: Ongoing research and perspectives

Wound healing response plays a central part in chronic inflammation, affecting millions of people worldwide. It is a dynamic process that can lead to fibrosis, if tissue damage is irreversible and wound resolution is not attained. It is clear that there is a tight interconnection among wound healing, fibrosis and a variety of chronic disease conditions, demonstrating the heterogeneity of this pathology. Based on our further understanding of the cellular and molecular mechanisms underpinning tissue repair, new therapeutic approaches have recently been developed that target different aspects of the wound healing process and fibrosis. Nevertheless, several issues still need to be taken into consideration when designing modern wound healing drug delivery formulations. In this review, we highlight novel pharmacological agents that hold promise for targeting wound repair and fibrosis. We also focus on drug-delivery systems that may enhance current and future therapies.

The promotion function of Berberine for osteogenic differentiation of human periodontal ligament stem cells via ERK-FOS pathway mediated by EGFR

Coptidis Rhizoma binds to the membrane receptors on hPDLSC/CMC, and the active ingredient Berberine (BER) that can be extracted from it may promote the proliferation and osteogenesis of periodontal ligament stem cells (hPDLSC). The membrane receptor that binds with BER on the cell surface of hPDLSC, the mechanism of direct interaction between BER and hPDLSC, and the related signal pathway are not yet clear. In this research, EGFR was screened as the affinity membrane receptor between BER and hPDLSC, through retention on CMC, competition with BER and by using a molecular docking simulation score. At the same time, the MAPK PCR Array was selected to screen the target genes that changed when hPDLSC was simulated by BER. In conclusion, BER may bind to EGFR on the cell membrane of hPDLSC so the intracellular ERK signalling pathways activate, and nuclear-related genes of FOS change, resulting in the effect of osteogenesis on PDLSC.

Bone Regeneration with a Combination of Adipose-Derived Stem Cells and Platelet-Rich Plasma

Mesenchymal stem cells (MSCs) have the potential to directly differentiate into osteogenic cells and efficiently regenerate bone tissue. Adipose-derived stem cells (ASCs) have the potential to differentiate into an osteogenic lineage, too. In addition, ASCs can be readily harvested in large numbers with low donor-site morbidity. Meanwhile, recent reports have demonstrated that platelet-rich plasma (PRP) contains a variety of growth factors and may be a powerful biological autologous cocktail of growth factors for tissue engineering.We have shown that ASC/PRP admixture had dramatic effects on bone regeneration in a rat calvarial defect model, not only through the osteogenic potential of ASCs, but also through the release of cytokines by platelets in PRP, which, in turn, support ASCs.In this chapter, we introduce the bone regeneration using a combination of ASCs and PRP in a rat calvarial defect model.

Effects of coenzyme Q10 encapsulated in nanoliposomes on wound healing processes after tooth extraction

Background/purpose

Tooth extraction is often followed by a number of different complications that demand additional treatment. In order to accelerate healing processes and decrease the complication occurrence various agents, growth factors, natural and synthetic antioxidants (e.g coenzyme Q₁₀-CoQ₁₀), are applied. Due to the partially known health-promoting effects of CoQ₁₀ we decided to assess potential of it's encapsulated in nanoliposomes form on wound healing process following tooth extraction.

Materials and methods

Effects of free and encapsulated form of CoQ₁₀ on wound healing processes after tooth extraction in rats, 3 and 7 days following surgical procedure, was studied by means of tissue biochemical (myeloperoxidase activity and nitric oxide (NO) concentrations) and pathohistological analysis.

Results

The obtained results indicate that the encapsulated form of CoQ₁₀ compared to control and CoQ₁₀ treated animals statistically significantly decreases inflammatory process estimated through myeloperoxidase activity and NO concentrations, as well as based on histopathological analysis 3 and 7 days following surgery.

Conclusion

The results of this study unequivocally prove that the encapsulation of CoQ₁₀ in nanoliposomes enhances CoQ₁₀ activity by accelerating wound healing process after tooth extraction.

Nanoparticles for bone tissue engineering

Tissue engineering (TE) envisions the creation of functional substitutes for damaged tissues through integrated solutions, where medical, biological, and engineering principles are combined. Bone regeneration is one of the areas in which designing a model that mimics all tissue properties is still a challenge. The hierarchical structure and high vascularization of bone hampers a TE approach, especially in large bone defects. Nanotechnology can open up a new era for TE, allowing the creation of nanostructures that are comparable in size to those appearing in natural bone. Therefore, nanoengineered systems are now able to more closely mimic the structures observed in naturally occurring systems, and it is also possible to combine several approaches - such as drug delivery and cell labeling - within a single system. This review aims to cover the most recent developments on the use of different nanoparticles for bone TE, with emphasis on their application for scaffolds improvement; drug and gene delivery carriers, and labeling techniques. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:590-611, 2017.

Bone Regeneration Using Gene-Activated Matrices

Gene delivery to bone is a potential therapeutic strategy for directed, sustained, and regulated protein expression. Tissue engineering strategies for bone regeneration include delivery of proteins, genes (viral and non-viral-mediated delivery), and/or cells to the bone defect site. In addition, biomimetic scaffolds and scaffolds incorporating bone anabolic agents greatly enhance the bone repair process. Regional gene therapy has the potential of enhancing bone defect healing and bone regeneration by delivering osteogenic genes locally to the osseous lesions, thereby reducing systemic toxicity and the need for using supraphysiological dosages of therapeutic proteins. By implanting gene-activated matrices (GAMs), sustained gene expression and continuous osteogenic protein production in situ can be achieved in a way that stimulates osteogenesis and bone repair within osseous defects. Critical parameters substantially affecting the therapeutic efficacy of gene therapy include the choice of osteogenic transgene(s), selection of non-viral or viral vectors, the wound environment, and the selection of ex vivo and in vivo gene delivery strategies, such as GAMs. It is critical for gene therapy applications that clinically beneficial amounts of proteins are synthesized endogenously within and around the lesion in a sustained manner. It is therefore necessary that reliable and reproducible methods of gene delivery be developed and tested for their efficacy and safety before translating into clinical practice. Practical considerations such as the age, gender, and systemic health of patients and the nature of the disease process also need to be taken into account in order to personalize the treatments and progress towards developing a clinically applicable gene therapy for healing bone defects. This review discusses tissue engineering strategies to regenerate bone with specific focus on non-viral gene delivery systems.

Effect of PDGF-BB, IGF-I growth factors and their combination carried by liposomes in tooth socket healing

This work evaluated the bone-forming potential of the platelet-derived growth factor isoform BB (PDGF-BB), insulin-like growth factor I (IGF-I), and mixed PDGF-BB/IGF-I delivered in liposomes compared with phosphate buffered saline (PBS), in the healing process of rat tooth sockets. One hundred and twelve Wistar rats were randomized into 7 groups of 16 animals each and were evaluated at 3, 7, 14 and 21 days after extraction of the maxillary second molars. The left sockets were treated with PBS (P), empty liposome (L), IGF-I in PBS (IP), IGF-I in liposome (IL), PDGF-BB in PBS (PDP), PDGF-BB in liposome (PDL) and both growth factors (GFs) together within liposomes (PDIL). The right sockets were filled with blood clot (BC). Histological and histomorphometric analyses were used to evaluate the formation of new bone and blood vessels. Immunohistochemistry was performed to evaluate the expression of osteocalcin and vascular endothelial growth factor (VEGF) during bone repair. Data were tested statistically using a Tukey's test according to a Dunn's analysis and Mann-Whitney U test followed by Kruskal-Wallis one-way analysis. Results were considered significant when p<0.05. A significantly higher percentage of bone trabeculae and a higher number of blood vessels were observed in the IL, PDL and PDIL groups (p<0.05). However, these GF-liposome groups had statistically similar results. Immunohistochemical assays first detected osteocalcin and VEGF expression at 3 days followed by a peak at 7 days. Lower immunoreactivity levels were observed in the BC, L, P, IP and PDP groups compared with the IL, PDL and PDIL groups (p<0.05). The results suggest that GFs carried by liposomes, either in isolated or mixed forms, enhanced the healing process in rat tooth sockets. The differential expression of the osteogenic markers VEGF and osteocalcin in the early phases of bone healing support these findings.

Active macropinocytosis induction by stimulation of epidermal growth factor receptor and oncogenic Ras expression potentiates cellular uptake efficacy of exosomes

Exosomes are approximately 100-nm vesicles that consist of a lipid bilayer of cellular membranes secreted in large quantities from various types of normal and disease-related cells. Endocytosis has been reported as a major pathway for the cellular uptake of exosomes; however, the detailed mechanisms of their cellular uptake are still unknown. Here, we demonstrate the active induction of macropinocytosis (accompanied by actin reorganisation, ruffling of plasma membrane, and engulfment of large volumes of extracellular fluid) by stimulation of cancer-related receptors and show that the epidermal growth factor (EGF) receptor significantly enhances the cellular uptake of exosomes. We also demonstrate that oncogenic K-Ras-expressing MIA PaCa-2 cells exhibit intensive macropinocytosis that actively transports extracellular exosomes into the cells compared with wild-type K-Ras-expressing BxPC-3 cells. Furthermore, encapsulation of the ribosome-inactivating protein saporin with EGF in exosomes using our simple electroporation method produces superior cytotoxicity via the enhanced cellular uptake of exosomes. Our findings contribute to the biological, pharmaceutical, and medical research fields in terms of understanding the macropinocytosis-mediated cellular uptake of exosomes with applications for exosomal delivery systems.

Paracrine effect of mesenchymal stem cells derived from human adipose tissue in bone regeneration

Mesenchymal stem cell (MSC) transplantation has proved to be a promising strategy in cell therapy and regenerative medicine. Although their mechanism of action is not completely clear, it has been suggested that their therapeutic activity may be mediated by a paracrine effect. The main goal of this study was to evaluate by radiographic, morphometric and histological analysis the ability of mesenchymal stem cells derived from human adipose tissue (Ad-MSC) and their conditioned medium (CM), to repair surgical bone lesions using an in vivo model (rabbit mandibles). The results demonstrated that both, Ad-MSC and CM, induce bone regeneration in surgically created lesions in rabbit's jaws, suggesting that Ad-MSC improve the process of bone regeneration mainly by releasing paracrine factors. The evidence of the paracrine effect of MSC on bone regeneration has a major impact on regenerative medicine, and the use of their CM can address some issues and difficulties related to cell transplants. In particular, CM can be easily stored and transported, and is easier to handle by medical personnel during clinical procedures.

Can we enhance fracture vascularity: What is the evidence?

Angiogenesis is a vital component of bone healing. The formation of the new blood vessels at the fracture site restores the hypoxia and nutrient deprivation found at the early stages after fracture whilst at a later stage facilitates osteogenesis by the activity of the osteoprogenitor cells. Emerging evidence suggests that there are certain molecules and gene therapies that could promote new blood vessel formation and as a consequence enhance the local bone healing response. This article summarizes the current in vivo evidence on therapeutic approaches aiming at the augmentation of the angiogenic signalling during bone repair.

Expression and effects of epidermal growth factor on human periodontal ligament cells

Repair of damaged periodontal ligament (PDL) tissue is an essential challenge in tooth preservation. Various researchers have attempted to develop efficient therapies for healing and regenerating PDL tissue based on tissue engineering methods focused on targeting signaling molecules in PDL stem cells and other mesenchymal stem cells. In this context, we investigated the expression of epidermal growth factor (EGF) in normal and surgically wounded PDL tissues and its effect on chemotaxis and expression of osteoinductive and angiogenic factors in human PDL cells (HPDLCs). EGF as well as EGF receptor (EGFR) expression was observed in HPDLCs and entire PDL tissue. In a PDL tissue-injured model of rat, EGF and IL-1β were found to be upregulated in a perilesional pattern. Interleukin-1β induced EGF expression in HPDLCs but not EGFR. It also increased transforming growth factor-α (TGF-α) and heparin-binding EGF-like growth factor (HB-EGF) expression. Transwell assays demonstrated the chemotactic activity of EGF on HPDLCs. In addition, EGF treatment significantly induced secretion of bone morphogenetic protein 2 and vascular endothelial growth factor, and gene expression of interleukin-8 (IL-8), and early growth response-1 and -2 (EGR-1/2). Human umbilical vein endothelial cells developed well-formed tube networks when cultured with the supernatant of EGF-treated HPDLCs. These results indicated that EGF upregulated under inflammatory conditions plays roles in the repair of wounded PDL tissue, suggesting its function as a prospective agent to allow the healing and regeneration of this tissue.

Epidermal growth factor, from gene organization to bedside

In 1962, epidermal growth factor (EGF) was discovered by Dr. Stanley Cohen while studying nerve growth factor (NGF). It was soon recognized that EGF is the prototypical member of a family of peptide growth factors that activate the EGF receptors, and that the EGF/EGF receptor signaling pathway plays important roles in proliferation, differentiation and migration of a variety of cell types, especially in epithelial cells. After the basic characterization of EGF function in the first decade or so after its discovery, the studies related to EGF and its signaling pathway have extended to a broad range of investigations concerning its biological and pathophysiological roles in development and in human diseases. In this review, we briefly describe the gene organization and tissue distribution of EGF, with emphasis on its biological and pathological roles in human diseases.