Validation of the Osteomyelitis Induced by Methicillin-Resistant Staphylococcus aureus (MRSA) on Rat Model with Calvaria Defect.

BACKGROUND: Osteomyelitis resulting from bacterial strains, such as methicillin-resistant Staphylococcus aureus (MRSA) that are resistant to multiple drugs, brings further clinical challenges. There is currently no model of osteomyelitis induced by MRSA using rats with calvaria defects. So, We induced osteomyelitis in rat models with the calvaria bone defect. METHODS: The rats were randomly divided into six groups according to inoculation dose levels, which ranged from 6 × 100 to 6 × 105 CFU/5 µl. Bone tissues were retrieved from all rats used in the study and assessed using histology, microbiology, and radiobiology 4 weeks after surgery to evaluate the relationship between inoculation dose and infectivity. RESULTS: In Histological results, high levels of inflammatory responses, bone necrosis, and bacteria were observed in treatment groups G3 to G5. In IHC staining, high levels of cox-2 expression were observed in treatment groups G3. Microbiological observations also indicated that significantly higher numbers of CFUs were found in G3 to G5. In radiography results, the bone mineral density in G3 to G5 was significantly higher than in the control group, G1, and G2. Our results indicate that an inoculating dose of 6 × 103 CFU/5 µl is sufficient to induce the development of osteomyelitis in rat models. CONCLUSION: This study suggests that the minimum dose (6 × 103 CFU/5 µl) can induce osteomyelitis in calvaria rat model. This can offer information and ability of more accurately modeling osteomyelitis and simulating the challenge of osteomyelitis treat.

Offset of apparent hyperpolarized 13 C lactate flux by the use of adjuvant metformin in ionizing radiation therapy in vivo.

An increase in hyperpolarized (HP) [1-13 C]lactate production has been suggested as a biomarker for cancer occurrence as well as for response monitoring of cancer treatment. Recently, the use of metformin has been suggested as an anticancer or adjuvant treatment. By regulating the cytosolic NAD+ /NADH redox state, metformin stimulates lactate production and increases the HP [1-13 C]lactate conversion rate in the kidney, liver, and heart. In general, increased HP [1-13 C]lactate is regarded as a sign of cancer occurrence or tumor growth. Thus, the relationship between the tumor suppression effect of metformin and the change in metabolism monitored by HP [1-13 C]pyruvate MRS in cancer treatment needs to be investigated. The present study was performed using a brain metastasis animal model with MDA-MB-231(BR)-Luc breast cancer cells. HP [1-13 C]pyruvate MRS, T2 -weighted MRI, and bioluminescence imaging were performed in groups treated with metformin or adjuvant metformin and radiation therapy. Metformin treatment alone did not display a tumor suppression effect, and the HP [1-13 C]lactate conversion rate increased. In radiation therapy, the HP [1-13 C]lactate conversion rate decreased with tumor suppression, with a p-value of 0.028. In the adjuvant metformin and radiation treatment, the tumor suppression effect increased, with a p-value of 0.001. However, the apparent HP [1-13 C]lactate conversion rate (Kpl ) was observed to be offset by two opposite effects: a decrease on radiation therapy and an increase caused by metformin treatment. Although HP [1-13 C]pyruvate MRS could not evaluate the tumor suppression effect of adjuvant metformin and radiation therapy due to the offset phenomenon, metabolic changes following only metformin pre-treatment could be monitored. Therefore, our results indicate that the interpretation of HP [1-13 C]pyruvate MRS for response monitoring of cancer treatment should be carried out with caution when metformin is used as an adjuvant cancer therapy.

Comparison of DNA Damage and Apoptosis Induced By Silver Nanoparticle-containing Dressing Materials During Wound Healing.

INTRODUCTION: Silver nanoparticle (AgNP)-containing dressings are used worldwide for the treatment of wounds; however, many studies have indicated that AgNPs are toxic to humans and cause cell death, primarily via apoptosis. OBJECTIVE: In this study, the investigators compare the apoptotic effects of various AgNP dressing materials, with the hypothesis that nanosilver would be less toxic than ionic silver. MATERIALS AND METHODS: For the in vivo experiments, Sprague-Dawley (SD) and streptozotocin (STZ)-induced diabetic rats were treated with 5 dressing materials: Aquacel Ag (product A, silver ion; ConvaTec, Berkshire, UK), Acticoat (product B, AgNP; Smith & Nephew, Fort Worth, TX), Medifoam Silver (product C, silver ion; Genewel Science Co Ltd, Seongnam, South Korea), PolyMem Silver (product D, AgNP; Ferris Mfg Corp, Fort Worth, TX), and Vaseline-impregnated dressing gauze (control; Unilever, London, UK). All treatments were applied 3 times per week. After 14 days of treatment, the SD and STZ rats were euthanized, and wound samples were examined for apoptosis. The analysis included immunohistochemistry, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, Western blotting, and reverse transcription polymerase chain reaction for a semiquantitative evaluation of apoptosis. RESULTS: The AgNP-containing dressing materials were more cytotoxic than the silver dressings. Compared with the AgNP dressing materials, no significant levels of apoptotic factors were observed in the silver dressing-treated wounds. The TUNEL staining showed that product C-dressed wounds contained the most apoptotic cells, while some apoptotic cells were observed in product B-dressed wounds. Moreover, apoptotic gene expression was altered, including a decline in B-cell lymphoma-2 and activation of caspase-3. This was most evident in wounds treated with product C. Interestingly, apoptotic gene expression was not induced in product A-treated wounds. Finally, product D had a relatively lower silver concentration and was less toxic than products A-C. CONCLUSIONS: Dressing materials containing AgNP have an antimicrobial effect. However, the authors observed that some AgNP dressings induced DNA damage and apoptosis. Although AgNP dressings did not cause significant acute apoptotic effects, they should be examined for cytotoxic effects in chronic wounds and should be used with caution when treating chronic wounds and those with low bacteria counts.

Removal and killing of multispecies endodontic biofilms by N-acetylcysteine

ABSTRACT Removal of bacterial biofilm from the root canal system is essential for the management of endodontic disease. Here we evaluated the antibacterial effect of N-acetylcysteine (NAC), a potent antioxidant and mucolytic agent, against mature multispecies endodontic biofilms consisting of Actinomyces naeslundii, Lactobacillus salivarius, Streptococcus mutans and Enterococcus faecalis on sterile human dentin blocks. The biofilms were exposed to NAC (25, 50 and 100 mg/mL), saturated calcium hydroxide or 2% chlorhexidine solution for 7 days, then examined by scanning electron microscopy. The biofilm viability was measured by viable cell counts and ATP-bioluminescence assay. NAC showed greater efficacy in biofilm cell removal and killing than the other root canal medicaments. Furthermore, 100 mg/mL NAC disrupted the mature multispecies endodontic biofilms completely. These results demonstrate the potential use of NAC in root canal treatment.

Removal and killing of multispecies endodontic biofilms by N-acetylcysteine.

Removal of bacterial biofilm from the root canal system is essential for the management of endodontic disease. Here we evaluated the antibacterial effect of N-acetylcysteine (NAC), a potent antioxidant and mucolytic agent, against mature multispecies endodontic biofilms consisting of Actinomyces naeslundii, Lactobacillus salivarius, Streptococcus mutans and Enterococcus faecalis on sterile human dentin blocks. The biofilms were exposed to NAC (25, 50 and 100mg/mL), saturated calcium hydroxide or 2% chlorhexidine solution for 7 days, then examined by scanning electron microscopy. The biofilm viability was measured by viable cell counts and ATP-bioluminescence assay. NAC showed greater efficacy in biofilm cell removal and killing than the other root canal medicaments. Furthermore, 100mg/mL NAC disrupted the mature multispecies endodontic biofilms completely. These results demonstrate the potential use of NAC in root canal treatment.

An indirect method for in vivo T2 mapping of [1-13 C] pyruvate using hyperpolarized 13 C CSI.

An indirect method for in vivo T2 mapping of 13 C-labeled metabolites using T2 and T2 * information of water protons obtained a priori is proposed. The T2 values of 13 C metabolites are inferred using the relationship to T2 ' of coexisting 1 H and the T2 * of 13 C metabolites, which is measured using routine hyperpolarized 13 C CSI data. The concept is verified with phantom studies. Simulations were performed to evaluate the extent of T2 estimation accuracy due to errors in the other measurements. Also, bias in the 13 C T2 * estimation from the 13 C CSI data was studied. In vivo experiments were performed from the brains of normal rats and a rat with C6 glioma. Simulation results indicate that the proposed method provides accurate and unbiased 13 C T2 values within typical experimental settings. The in vivo studies found that the estimated T2 of [1-13 C] pyruvate using the indirect method was longer in tumor than in normal tissues and gave values similar to previous reports. This method can estimate localized T2 relaxation times from multiple voxels using conventional hyperpolarized 13 C CSI and can potentially be used with time resolved fast CSI.

Evaluation of the Effects of Air Pollutants on Diabetic Wounds.

BACKGROUND: Although air pollution containing fine dust particles is gaining attention worldwide, little is known about the effects of such pollutants on diabetic wounds. Air pollutants from diesel exhaust particles (DEPs) cause inflammation, resulting in an increased expression of pro-inflammatory cytokines and chemo- kines, which attract monocytes and T cells to the sites of inflamma- tion. The authors evaluated the effects of air pollutants on diabetic wounds. MATERIALS AND METHODS: Fibroblast cells were derived from streptozotocin-induced diabetic rats. Cell Counting Kit-8 assays were used to determine cell viability. The expression of pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α), cyclooxygen- ase-2 (COX-2), and interleukin-6 (IL-6) was evaluated by reverse transcription polymerase chain reaction and western blot analysis. RESULTS: The proliferation of DEP-treated fibroblasts decreased with time. The messenger ribonucleic acid expression of TNF-α and COX- 2 in DEP-treated fibroblasts increased in both normal and diabetic fibroblasts, while IL-6 expression remained unchanged. The protein expression of TNF-α, COX-2, and IL-6 in DEP-treated fibroblasts increased compared to samples not exposed to DEP. CONCLUSIONS: Diesel exhaust particles regulate the expression of pro-inflammatory cytokines such as IL-6, TNF-α, and COX-2, which may impede dia- betic healing in vitro.

Flow-suppressed hyperpolarized 13 C chemical shift imaging using velocity-optimized bipolar gradient in mouse liver tumors at 9.4 T.

PURPOSE: To optimize and investigate the influence of bipolar gradients for flow suppression in metabolic quantification of hyperpolarized 13 C chemical shift imaging (CSI) of mouse liver at 9.4 T. METHODS: The trade-off between the amount of flow suppression using bipolar gradients and T2* effect from static spins was simulated. A free induction decay CSI sequence with alternations between the flow-suppressed and non-flow-suppressed acquisitions for each repetition time was developed and was applied to liver tumor-bearing mice via injection of hyperpolarized [1-13 C] pyruvate. RESULTS: The in vivo results from flow suppression using the velocity-optimized bipolar gradient were comparable with the simulation results. The vascular signal was adequately suppressed and signal loss in stationary tissue was minimized. Application of the velocity-optimized bipolar gradient to tumor-bearing mice showed reduction in the vessel-derived pyruvate signal contamination, and the average lactate/pyruvate ratio increased by 0.095 (P < 0.05) in the tumor region after flow suppression. CONCLUSION: Optimization of the bipolar gradient is essential because of the short 13 C T2* and high signal in venous flow in the mouse liver. The proposed velocity-optimized bipolar gradient can suppress the vascular signal, minimizing T2*-related signal loss in stationary tissues at 9.4 T. Magn Reson Med 78:1674-1682, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Antibacterial effects of N-acetylcysteine against endodontic pathogens.

The success of endodontic treatment depends on the eradication of microorganisms from the root canal system and the prevention of reinfection. The purpose of this investigation was to evaluate the antibacterial and antibiofilm efficacy of N-acetylcysteine (NAC), an antioxidant mucolytic agent, as an intracanal medicament against selected endodontic pathogens. Minimum inhibitory concentrations (MICs) of NAC for Actinomyces naeslundii, Lactobacillus salivarius, Streptococcus mutans, and Enterococcus faecalis were determined using the broth microdilution method. NAC showed antibacterial activity, with MIC values of 0.78-1.56 mg/ml. The effect of NAC on biofilm formation of each bacterium and a multispecies culture consisting of the four bacterial species was assessed by crystal violet staining. NAC significantly inhibited biofilm formation by all the monospecies and multispecies bacteria at minimum concentrations of 0.78-3.13 mg/ml. The efficacy of NAC for biofilm disruption was evaluated by scanning electron microscopy and ATP-bioluminescence quantification using mature multispecies biofilms. Preformed mature multispecies biofilms on saliva-coated hydroxyapatite disks were disrupted within 10 min by treatment with NAC at concentrations of 25 mg/ml or higher. After 24 h of treatment, the viability of mature biofilms was reduced by > 99% compared with the control. Moreover, the biofilm disrupting activity of NAC was significantly higher than that of saturated calcium hydroxide or 2% chlorhexidine solution. Within the limitations of this in vitro study, we conclude that NAC has excellent antibacterial and antibiofilm efficacy against endodontic pathogens and may be used as an alternative intracanal medicament in root canal therapies.

Vitrified canine testicular cells allow the formation of spermatogonial stem cells and seminiferous tubules following their xenotransplantation into nude mice.

Belgian Malinois (BM), one of the excellent military dog breeds in South Korea, is usually castrated before sexual maturation. Therefore, the transfer of their genetic features to the next generation is difficult. To overcome this, testicular cells from 4-month-old BMs were frozen. Testicular cells were thawed after 3 months and cultured in StemPro-34 medium. Spermatogonial stem cell (SSC) characteristics were determined by the transplantation of the cultured germ cell-derived colonies (GDCs) into empty testes, containing only several endogenous SSCs and Sertoli cells, of immunodeficient mice, 4 weeks after busulfan treatment. Following the implantation, the transplanted cells localized in the basement membrane of the seminiferous tubules, and ultimately colonized the recipient testes. Xenotransplantation of GDCs together with testicular somatic cells conjugated with extracellular matrix (ECM), led to the formation of de novo seminiferous tubules. These seminiferous tubules were mostly composed of Sertoli cells. Some germ cells were localized in the basement membrane of seminiferous tubules. This study revealed that BM-derived SSCs, obtained from the castrated testes, might be a valuable tool for the transfer of BM genetic features to the next generation.

Potent In Vitro and In Vivo Activity of Plantibody Specific for Porphyromonas gingivalis FimA.

Fimbrial protein fimbrillin (FimA), a major structural subunit of Porphyromonas gingivalis, has been suggested as a vaccine candidate to control P. gingivalis-induced periodontal disease. Previously, cDNAs encoding IgG monoclonal antibodies (MAbs) against purified FimA from P. gingivalis 2561 have been cloned, and the MAbs have been produced in rice cell suspension. Here we examined the biological activities of the plant-produced MAb specific for FimA (anti-FimA plantibody) of P. gingivalis in vitro and in vivo. The anti-FimA plantibody recognized oligomeric/polymeric forms of native FimA in immunoblot analysis and showed high affinity for native FimA (KD = 0.11 nM). Binding of P. gingivalis (10(8) cells) to 2 mg of saliva-coated hydroxyapatite beads was reduced by 53.8% in the presence of 1 µg/ml plantibody. Anti-FimA plantibody (10 µg/ml) reduced invasion of periodontal ligament cells by P. gingivalis (multiplicity of infection, 100) by 68.3%. Intracellular killing of P. gingivalis opsonized with the anti-FimA plantibody by mouse macrophages was significantly increased (77.1%) compared to killing of bacterial cells with irrelevant IgG (36.7%). In a mouse subcutaneous chamber model, the number of recoverable P. gingivalis cells from the chamber fluid was significantly reduced when the numbers of bacterial cells opsonized with anti-FimA plantibody were compared with the numbers of bacterial cells with irrelevant IgG, 66.7% and 37.1%, respectively. These in vitro and in vivo effects of anti-FimA plantibody were comparable to those of the parental MAb. Further studies with P. gingivalis strains with different types of fimbriae are needed to investigate the usefulness of anti-FimA plantibody for passive immunization to control P. gingivalis-induced periodontal disease.

The Role of Foxo3 in Leydig Cells.

PURPOSE: Foxo3 in female reproduction has been reported to regulate proliferation of granulose cells that form follicles. There are no reports so far that discuss on the role of Foxo3 in males. This study was designed to outline the role of Foxo3 in the testes. MATERIALS AND METHODS: Testes from mice at birth to postpartum week (PPW) 5 were isolated and examined for the expression of Foxo3 using immunostaining. To elucidate role of Foxo3 in Leydig cells, R2C cells were treated with luteinizing hormone (LH) and the phosphorylation of Foxo3. Testosterone and steroidogenic acute regulatory (StAR) protein levels were measured after constitutive active [triple mutant (TM)] human FOXO3 adenovirus was transduced and StAR promoter assay was performed. RESULTS: Foxo3 expression in the testicles started from birth and lasted until PPW 3. After PPW 3, most Foxo3 expression occurred in the nuclei of Leydig cells; however, at PPW 5, Foxo3 was expressed in both the nucleus and cytoplasm. When R2C cells were treated with luteinizing hormone, Foxo3 phosphorylation levels by AKT increased. After blocking the PI3K pathway, LH-induced phosphorylated Foxo3 levels decreased, indicating that LH signaling regulates Foxo3 localization. When active FOXO3-TM adenovirus was introduced into a Leydig tumor cell line, the concentrations of testosterone and StAR protein decreased. When FOXO3 and a StAR promoter vector were co-transfected into HEK293 cells for a reporter assay, FOXO3 inhibited the StAR promoter. CONCLUSION: FOXO3 affects testosterone synthesis by inhibiting the formation of StAR protein. LH hormone, meanwhile, influences Foxo3 localization, mediating its function.

Toward Accumulation of Magnetic Nanoparticles into Tissues of Small Porosity.

Magnetic concentration of drug-laden magnetic nanoparticles has been proven to increase the delivery efficiency of treatment by 2-fold. In these techniques, particles are concentrated by the presence of a magnetic source that delivers a very high magnetic field and a strong magnetic field gradient. We have found that such magnetic conditions cause even 150 nm particles to aggregate significantly into assemblies that exceed several micrometers in length within minutes. Such assembly sizes exceed the effective intercellular pore size of tumor tissues preventing these drug-laden magnetic nanoparticles from reaching their target sites. We demonstrate that by using dynamic magnetic fields instead, we can break up these magnetic nanoparticles while simultaneously concentrating them at target sites. The dynamic fields we investigate involve precessing the field direction while maintaining a field gradient. Manipulating the field direction drives the particles into attractive and repulsive configurations that can be tuned to assemble or disassemble these particle clusters. Here, we develop a simple analytic model to describe the kinetic thresholds of disassembly and we compare both experimental and numerical results of magnetic particle suspensions subjected to dynamic fields. Finally we apply these methods to demonstrate penetration in a porous scaffold with a similar pore size to that expected of a tumor tissue.

Effects of Iron-Oxide Nanoparticle Surface Chemistry on Uptake Kinetics and Cytotoxicity in CHO-K1 Cells.

Superparamagnetic iron-oxide nanoparticles (SPIONs) show great promise for multiple applications in biomedicine. While a number of studies have examined their safety profile, the toxicity of these particles on reproductive organs remains uncertain. The goal of this study was to evaluate the cytotoxicity of starch-coated, aminated, and PEGylated SPIONs on a cell line derived from Chinese Hamster ovaries (CHO-K1 cells). We evaluated the effect of particle diameter (50 and 100 nm) and polyethylene glycol (PEG) chain length (2k, 5k and 20k Da) on the cytotoxicity of SPIONs by investigating cell viability using the tetrazolium dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and sulforhodamine B (SRB) assays. The kinetics and extent of SPION uptake by CHO-K1 cells was also studied, as well as the resulting generation of intracellular reactive oxygen species (ROS). Cell toxicity profiles of SPIONs correlated strongly with their cellular uptake kinetics, which was strongly dependent on surface properties of the particles. PEGylation caused a decrease in both uptake and cytotoxicity compared to aminated SPIONs. Interestingly, 2k Da PEG-modifed SPIONs displayed the lowest cellular uptake and cytotoxicity among all studied particles. These results emphasize the importance of surface coatings when engineering nanoparticles for biomedical applications.

FoxO1 is a negative regulator of FSHß gene expression in basal and GnRH-stimulated conditions in female.

The importance of forkhead box class O (FoxO) proteins in reproductive endocrinology has been confirmed by age-dependent infertility in females in a FoxO3a-knockout mouse model. In this study, FoxO1 was detected in gonadotropes in the anterior pituitary. Overexpression of FoxO1 in primary pituitary cells decreased FSHß gene expression in both basal and GnRH-stimulated conditions, and this result was replicated by the human FSHß promoter activity. Although direct binding of FoxO1 to FoxO-binding element (FBE) (at -124 to -119 bp of the human FSHß promoter) was not detected in an electrophoretic mobility shift assay, a DNA pull-down assay and transfection study using the mutant FBE reporter vector revealed that FBE is necessary in FSHß suppression by FoxO1, suggestive of other cofactor requirements. GnRH stimulated the phosphoinositide 3-kinase pathway, which induced posttranslational modification of FoxO1 and retained it in the cytoplasm. We also confirmed this result in primary cell cultures; most of the FoxO1 was detected in the cytoplasm when treated with GnRH but in the nucleus when the phosphoinositide 3-kinase pathway was inhibited. These findings suggest that FoxO1 is regulated by the GnRH signaling pathway and functions as a negative regulator of FSHß gene expression.

Elevation of S100 calcium binding protein A9 in sputum of neutrophilic inflammation in severe uncontrolled asthma.

BACKGROUND: Neutrophilic airway inflammation is frequently observed in severe uncontrolled asthma (UA) and controlled asthma (CA). However, there is no sputum biomarker to differentiate the 2 conditions. OBJECTIVE: To identify biomarkers of severe uncontrolled asthma with neutrophilic airway inflammation. METHODS: Sputum with a neutrophil content larger than 70% was pooled from 5 patients with severe UA and from 10 patients with CA. Two-dimensional electrophoresis was adopted for differential display proteomics, and candidate proteins were identified using matrix-assisted laser adsorption/ionization-time of flight mass spectrometric analysis. S100 calcium binding protein A9 (S100A9) was identified by western blot and its level was measured in sputum from asthmatics with varying disease severity, patients with chronic obstructive lung disease, and normal controls using enzyme-linked immunosorbent assay. RESULTS: Fourteen protein spots exhibited differences in relative intensity between patients with severe UA and those with CA. Matrix-assisted laser adsorption/ionization-time of flight/time of flight of these spots showed an increase in human neutrophil peptide-2, S100A9, ß-amylase, neutrophil gelatinase-associated lipocalin, 4-aminobutyrate transaminase, and cystatin SA in patients with UA compared with patients with CA. There was a decrease in the plunc precursor, complement C3 component, immunoglobulin heavy-chain variable region, glial fibrillary acidic protein isoform-1, IgM κIIIb SON, MLL-AF4 der(11) fusion protein, cytokeratin-8, and recombinant IgG4 heavy chain. S100A9 was detected at a higher level in western blots of neutrophilic sputum from patients with severe UA vs CA. S100A9 levels were significantly increased, as measured by enzyme-linked immunosorbent assay, in neutrophilic UA compared with CA, eosinophilic UA and CA, and chronic obstructive lung disease. CONCLUSION: S100A9 in sputum may be a biomarker of neutrophilic inflammation in severe UA.

Peptide-mediated intracellular delivery of miRNA-29b for osteogenic stem cell differentiation.

Stem cell differentiation is modulated by several key molecules, including cytokines, hormones, and engineered peptides. Emerging evidence suggests that microRNA has potential applications in stem cell engineering, such as in osteoblastic differentiation. MicroRNAs (miRNAs) bind to the 3'-untranslated region (UTR) sequence of target mRNA, thereby attenuating protein synthesis. Our goal was to evaluate the delivery of miRNA, i.e., miRNA-29b, to stem cells to promote osteoblastic differentiation because this miRNA is known to target anti-osteogenic factors gene expression. Despite the important role of miRNAs, their application has been limited due to poor cell/tissue penetration. The authors attempted to overcome this limitation by using a cell-penetrating peptide (CPP) carrier. Herein, the arginine-rich CPP, called the lowmolecular weight protamine (LMWP), is the sequence from natural protamine. We worked out the difficult problem to transfect into hMSCs by the complex with LMWP, and then we investigated synthetic double-stranded miR-29b could be induced osteoblast differentiation.

The mineralization inducing peptide derived from dentin sialophosphoprotein for bone regeneration.

Dentin sialophosphoprotein (DSPP) has been shown to play a primary role in the formation and growth of hydroxyapatite crystals in an extracellular matrix of hard tissue such as bone and teeth. We hypothesized that the mineralization ability of DSPP might depend on a specific domain within it. Three peptides, which have hydroxyapatite (HA) binding affinity, denoted as mineralization inducing peptide (MIP1, MIP2, and MIP3) were identified from DSPP. The both of MIP2 and MIP3 had HA nucleation activity demonstrated by XRD. Among three MIPs, MIP3 significantly supported the human bone marrow stromal cell differentiation into osteoblastic cells. An immunoblot with antibodies specific for the phosphorylated forms of ERK was conducted with cells treated by MIP3. MIP3 transduced intracellular signals via the ERK pathways and was able to induce osteoblastic differentiation, as seen by high expression of ALP, type 1 collagen, OC, OPN, and Runx2 in accordance with applied MIP3 concentration. The Asp, Glu, and Ser residues in MIP3 play important roles for the affinity of calcium in HA bone mineral. Further animal experiment with MIP3 in combination with hydroxyapatite mineral induced marked new bone formation for 4 weeks at rabbit calvarial defect model. The new bone area was much higher in test group, implying that the peptide modified group had excellent biocompatibility when compared with the unmodified group. Taken together, the MIP from DSPP has potential to enhance mineralization followed by to enhance osteoblastic differentiation and bone regeneration.

Bioactive peptide-modified biomaterials for bone regeneration.

Bioactive biomaterials are desirable as tissue engineering scaffolds by virtue of their capability to mimic the natural environment of the extracellular matrix. Bioactive biomaterials have been achieved by incorporating synthetic short peptide sequences into suitable materials either by surface modification or by bulk incorporation. The goal is to enhance cell attachment and other basic functions. Bioactive peptides can be obtained from biological or chemically synthesized sources, increasing their specific cellular responses for tissue growth and development. Compared to using an entire growth factor in regenerative therapy, these peptides demonstrate potential advantages such as overcoming possible immunogenicity, being less susceptible to degradation, and producing fewer tumor-related side effects. Biomaterial scaffolds modified with peptides can provide biological ligands for cell-scaffold interactions that promote cell attachment, proliferation, and differentiation. Peptide-based biomaterial scaffolds can be fabricated to form two- and three-dimensional structures. This review discusses cell-binding, biominerailization inducing peptides, and receptor-binding peptides for bone regeneration. This review also addresses issues related to peptide immobilization as well as potential complications that may develop as a result of using these versatile bioactive peptides. The development of self-assembled peptide amphiphiles with the goal of generating new three-dimensional scaffolds for tissue engineering is also summarized.

Cell penetrating peptides for tumor targeting.

Anticancer drug delivery has been hindered due to cell membrane permeability and the lack of a selective marker for tumor cells. Cell permeability is related to the bioavailability of drugs and has therefore been considered to be an essential step for achieving therapeutic efficacy. While different types of transporters currently exist, cell penetrating peptides (CPPs) have become one of the most popular and effective tools for intracellular drug delivery. Most of the original CPPs are short peptides with basic residues. The mechanism of CPP cell entry remains to be established; however, the CPPs can deliver any type of molecular cargo including solid nanoparticles. Herein, this paper will discuss the classification of CPPs, the mechanism of cell entry, the application of CPPs in tumor therapy, and recent advances in targeted cell penetration that involve CPPs.