Peptide decorated demineralized dentin matrix with enhanced bioactivity, osteogenic differentiation via carboxymethyl chitosan.

OBJECTIVES: To improve the biocompatibility and osteogenic activity of demineralized dentin matrix (DDM) by grafting peptides on its surface. METHODS: DDM was obtained by pulverizing extracted human teeth that had been systematically demineralized and dried. Four groups of materials were evaluated: DDM, DDM/carboxymethyl chitosan (CMC), DDM/CMC/bone forming peptide-1 (BFP-1), and blank. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and fluorescence localization were used to characterize the surface of the DDM materials. Cell viability was assessed using a CCK8 assay, scanning electron microscopy (SEM) and in vitro osteogenesis was analyzed using real-time RT-PCR (RT-qPCR) and Alizarin red and alkaline phosphatase staining. Three different materials were implanted into mandibular bone defects in rats. After 8 weeks, bone regeneration was assessed by histomorphometry of HE-stained slides. RESULTS: FT-IR, XPS, and fluorescence microscopy demonstrated that the DDM surfaces were successfully modified with BFP-1. The CCK8 assay indicated that the proliferation of cells is higher on the DDM/CMC/BFP-1 material than on DDM or DDM/CMC (P < 0.05). Cells were more likely to adhere to DDM/CMC/BFP-1, as observed by SEM. Greater in vitro osteogenesis was observed in the DDM/CMC/BFP-1 group which displayed stronger alkaline phosphatase activity, more alizarin red-stained nodules, and higher target gene expression, as detected by RT-qPCR (P＜0.05). HE staining of in vivo explants indicated that greater quantities of new bone had formed in the DDM/CMC/BFP-1 group. SIGNIFICANCE: Compared with DDM, DDM/CMC/BFP-1 exhibited superior biocompatibility and osteogenesis, using a method of surface modification that has great potential for future clinical use.

Toothbrushing, Blood Glucose and HbA1c: Findings from a Random Survey in Chinese Population.

Both diabetes and periodontal disease are prevalent in China. Poor oral hygiene practice is the major cause of periodontal disease. An association between oral hygiene practice and blood glucose level was reported in individuals with diabetes, but not in the general population. We examined the association in a population-based random survey recruiting 2,105 adults without previously diagnosed diabetes in Chongqing city, China. Plasma glucose and hemoglobin A1c (HbA1c) were measured, and a 2-hour oral glucose tolerance test was conducted for each respondent. Self-reported toothbrushing frequency was used as a proxy for oral hygiene practice. In a linear model controlling for potential confounders (demographic characteristics, socio-economic status, lifestyle risk factors, BMI, dental visit frequency, etc.), urban residents who barely brushed their teeth had an increase of 0.50 (95% CI: 0.10-0.90) mmol/L in fasting plasma glucose, and an increase of 0.26% (0.04-0.47%) in HbA1c, relative to those brushing ≥twice daily; for rural residents, the effects were 0.26 (0.05-0.48) mmol/L in fasting plasma glucose and 0.20% (0.09-0.31%) in HbA1c. Individuals with better oral practice tended to have lower level of blood glucose and HbA1c. Establishing good oral health behavioral habits may be conducive to diabetes prevention and control in the general population.

Decoration of heparin and bovine serum albumin on polysulfone membrane assisted via polydopamine strategy for hemodialysis.

Renal failure brings about abnormality of waste and toxins and deposition in the body. In clinic, the waste and toxins in vitro are eliminated by hemodialysis device with polysulfone (PSF) porous membranes. In the work, decoration of heparin (Hep) and bovine serum albumin (BSA) on PSF membranes would be beneficial to improve the hemocompatibility and reduce the anaphylatoxin formation during hemodialysis. The PSF porous membranes are surface-modified by simply dipping them into dopamine aqueous solution for 8 h. Then, Hep and BSA are immobilized covalently onto the resultant membrane. Attenuated total reflectance Fourier transform infrared spectra (ATR-FTIR) confirms that Hep and BSA are successfully introduced onto the surface of PSF membranes. Scanning electronic microscopy (SEM) and atomic force microscopy (AFM) display the changes of surface morphologies after modification. The result of water contact angle measurement shows that the hydrophilicity of PSF membranes is remarkably improved after coating polydopamine (pDA) and binding Hep and BSA. The experiments of hemocompatibility indicate that Hep and BSA grafted onto membranes suppress the adhesion of platelet and enhance the anticoagulation ability of PSF membranes. Furthermore, the protein adsorption tests reveal that Hep and BSA immobilized onto membranes depress the protein absorption and develop antifouling-protein ability of pristine membrane. This study proves a convenient and simple approach to graft two functional organic polymers which, respectively, play a vital role and then improve the hemocompatibility and biocompatibility of PSF membranes for their biomedical and blood-contacting applications.

Osteoinductive peptide-functionalized nanofibers with highly ordered structure as biomimetic scaffolds for bone tissue engineering.

The construction of functional biomimetic scaffolds that recapitulate the topographical and biochemical features of bone tissue extracellular matrix is now of topical interest in bone tissue engineering. In this study, a novel surface-functionalized electrospun polycaprolactone (PCL) nanofiber scaffold with highly ordered structure was developed to simulate the critical features of native bone tissue via a single step of catechol chemistry. Specially, under slightly alkaline aqueous solution, polydopamine (pDA) was coated on the surface of aligned PCL nanofibers after electrospinning, followed by covalent immobilization of bone morphogenetic protein-7-derived peptides onto the pDA-coated nanofiber surface. Contact angle measurement, Raman spectroscopy, and X-ray photoelectron spectroscopy confirmed the presence of pDA and peptides on PCL nanofiber surface. Our results demonstrated that surface modification with osteoinductive peptides could improve cytocompatibility of nanofibers in terms of cell adhesion, spreading, and proliferation. Most importantly, Alizarin Red S staining, quantitative real-time polymerase chain reaction, immunostaining, and Western blot revealed that human mesenchymal stem cells cultured on aligned nanofibers with osteoinductive peptides exhibited enhanced osteogenic differentiation potential than cells on randomly oriented nanofibers. Furthermore, the aligned nanofibers with osteoinductive peptides could direct osteogenic differentiation of human mesenchymal stem cells even in the absence of osteoinducting factors, suggesting superior osteogenic efficacy of biomimetic design that combines the advantages of osteoinductive peptide signal and highly ordered nanofibers on cell fate decision. The presented peptide-decorated bone-mimic nanofiber scaffolds hold a promising potential in the context of bone tissue engineering.

[Influence of healing process of extraction on related growth factors in microscrew-bone interface of implanted titanium microscrews near the extraction wounds].

OBJECTIVE: To detect the expression of growth factors relating to bone reconstructions in microscrew-bone interface of implanted titanium microscrews near the extraction wounds, and to determine the influence of healing process on the growth factors. METHODS: Eight male Beagle dogs (age 18 months) were divided into experimental and control groups. Titanium microscrews were implanted near an extraction wound in the dogs in the experimental group, while the controls had implantation without extraction wounds. The dogs were sacrificed at 1, 3, 8, 12 weeks, respectively. Immunohistochemistry and in situ hybridization sections were performed to detect the expression of TGF-beta, TNF-alpha, osteocalcin (OC) protein and Cbfal mRNA. RESULTS: The experimental group had higher levels of expression of TGF-beta, TNF-alpha protein and Cbfa1 mRNA than the controls, with significant differences appearing at week one for TNF-alpha (P<0.05), week three for TGF-beta and TNF-alpha (P<0.05), and week eight for Cbfa1 mRNA (P<0.05). The expression of OC increased over time and reached peak at week eight (P<0.05). CONCLUSION: Microscrews implanted near extraction wounds can maintain stability. Severe inflammation occurs in the early stage of healing, but does not sustain. Bone remodeling remains active over the healing process. But prolonged healing phase without force loading could weaken the remodeling.

In vitro culture and directed osteogenic differentiation of human pluripotent stem cells on peptides-decorated two-dimensional microenvironment.

Human pluripotent stem cells (hPSCs) are a promising cell source with pluripotency and capacity to differentiate into all human somatic cell types. Designing simple and safe biomaterials with an innate ability to induce osteoblastic lineage from hPSCs is desirable to realize their clinical adoption in bone regenerative medicine. To address the issue, here we developed a fully defined synthetic peptides-decorated two-dimensional (2D) microenvironment via polydopamine (pDA) chemistry and subsequent carboxymethyl chitosan (CMC) grafting to enhance the culture and osteogenic potential of hPSCs in vitro. The hPSCs including human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) were successfully cultured on the peptides-decorated surface without Matrigel and ECM protein coating and underwent promoted osteogenic differentiation in vitro, determined from the alkaline phosphate (ALP) activity, gene expression, and protein production as well as calcium deposit amount. It was found that directed osteogenic differentiation of hPSCs was achieved through a peptides-decorated niche. This chemically defined and safe 2D microenvironment, which facilitates proliferation and osteo-differentiation of hPSCs, not only helps to accelerate the translational perspectives of hPSCs but also provides tissue-specific functions such as directing stem cell differentiation commitment, having great potential in bone tissue engineering and opening new avenues for bone regenerative medicine.