Mehmet Ali Onur

Effect of Enamel Matrix Derivative on Mouse Fibroblasts and Marrow Stromal Osteoblasts

There is increasing evidence that the cells of the epithelial root sheath synthesize enamel matrix proteins and that these proteins play a fundamental role in cementogenesis and periodontal tissue formation. Emdogain, enamel matrix derivative (EMD), is a porcine enamel matrix derived product used to enhance regeneration of the peridontium after inflammatory destruction. Today, little is known about EMDs potential regenerative properties on cell function. The purpose of this study was to investigate the effects of EMD on mouse fibroblasts (L 929 cells) and rat marrow stromal osteoblasts. For effects on cell proliferation, the L 929 cell lines were plated in 24-well culture plates at an initial density of 10,000 cell/mL and allowed to attach. Following a 24-h incubation within Dulbeccos modified eagle medium (DMEM) enriched with 10% fetal bovine serum, DMEM supplemented with 0 (Control), 50 μg/mL and 100 μg/mL of EMD was added and cultures maintained for 96 h. Cell proliferation was measured at 24, 48, 72 and 96 h as the total cell number per well and cell morphology was investigated. Osteoblasts were digested from mouse tibia marrow and were plated in similar manner as with L 929 cells, while the observation periods were 2, 6, 8 and 10 days in this group. Although both cell types were able to maintain their original cell morphology throughout the tests, in both cell groups the number of cells in the EMD groups at each observation period were not significantly different than that in the control group (ANOVA, p > 0.05). Moreover, EMD failed to show any impact on cell growth with higher concentration (ANOVA, p > 0.05). These results suggest that although EMD had no cytotoxic effect on mouse fibroblasts and stromal marrow osteoblasts, the same material failed to enhance the growth of both cell types.

Comparison of cellular proliferation on dense and porous PCL scaffolds.

In this contribution, PCL (poly-epsilon caprolactone) scaffolds were prepared by solvent-casting/particle-leaching technique in the presence of two pore formers, PEG(4000) or sucrose molecules in different quantities (0, 10, 20, 30, 40, 50, 55 w/w% PEG(4000)/PCL; 10, 20 w/w% Sucrose/PCL). The surface and bulk properties of the resulting scaffolds were studied by SEM, DSC and FTIR. SEM photographs showed that, macroporosity was obtained in the PCL structures prepared with sucrose crystals while microporous structure was obtained in the presence of PEG(4000) molecules. Average pore diameters calculated from SEM photographs were 40.1 and 191.2 mum for 40% PEG(4000)/PCL and 10% Sucrose/PCL scaffolds, respectively. The DSC and FTIR results confirmed that there is no any interaction between pore formers and PCL during structural formation, and both pore formers, PEG(4000) and sucrose, remained independently in the scaffolds. L929 mouse fibroblast cells were seeded onto PCL structures and maintained during 7 days to evaluate cell proliferation. Cell culture results showed that, 10% Sucrose/PCL scaffold was the most promising substrate for L929 cell growth due to 3-D architecture and macroporous structure of the scaffold.

Clinical impact and biomaterial evaluation of autologous platelet gel in cardiac surgery

We compared the clinical efficacy of autologous platelet gel (APG) and gelatine (CONT), including biomaterial evaluation. In a prospective, randomized, controlled trial, 64 patients undergoing complex coronary artery bypass graft (CABG) surgery and/or aortic surgery, in whom the surgeon was able to identify a bleeding site for which conventional means to stop bleeding were impractical or proved unsuccessful, were enrolled. Aortic punch biopsy from each patient was harvested in explant cell (EC) culture media. Hemostasis success for the “oozing” category was 89% in APG and 60% in CONT (p< 0.05). For the “heavy bleeding” category, the success rates were 92% in APG and 45% in CONT (p<0.01). Contact of gelatine inhibited EC proliferation and APG increased cell cycling and EC quantity. Phagocytic capacity (PC) was significantly higher in the APG group (p<0.001). APG was significantly better than CONT with respect to hemostatic success rate, effects on wound healing and increased resistance to infection (PC).

Effect of a fifth-generation bonding agent on vascular responses in rats.

In the last years, several single-bottle dental adhesives have been developed. They are supposed to chemically adhere to dentin, and a liner to protect pulp is not thought to be necessary. In the case of direct pulp capping, hemorrhage control is an important step in success, but little is known about the effect of these new bonding agents on pulpal bleeding. The aim of this study was to evaluate the effect of a new one-step single-bottle adhesive on the smooth muscle contraction of rat uterine muscle and carotid arteries. Efficacy of the bonding agent was compared with that of epinephrine (control), and the contraction forces induced were recorded using a force displacement transducer. Statistical analysis of data revealed that the bonding material produced epinephrine-like concentration-dependent contractions of the smooth muscle, suggesting that one-step bonding agents may act as candidates for hemorrhage control without the use of an additional agent in direct pulp capping procedures.

Vascular Response of Current and Potential Dental Etchants

This study investigated the hemostatic properties of current and potential dentin conditioners by observing the contraction of blood vessels using the rat carotid artery model. Four different agents (3M Scotchbond etchant, NRC, RC-Prep, File-Eze) were used. Dose-dependent contractions/relaxations of the test materials were first compared with epinephrine, followed by administration of papaverine, which was used to reverse epinephrine-induced contractions. In all sequences, the contraction or relaxation forces produced by the test and control materials were recorded using a force displacement transducer. RC-Prep was the only agent to produce epinephrine-like contractions (vasoconstriction) in the rat carotid artery. No contraction could be achieved with 3M etchant. Dose-dependent relaxations were observed with 3M etchant, which eventually led to collapse of the vessel wall; afterward, no response could be achieved with administration of adrenalin. File-Eze and NRC also did not cause vasoconstriction. Both materials caused dose-dependent relaxations in the smooth muscle. However, subsequent administration of adrenalin and papaverine caused dose-dependent contractions and relaxations, respectively, showing that these etchant effects did not lead to collapse of the vessel wall, as did 3M etchant.

Conjugation of Polymer-Coated Gold Nanoparticles with Antibodies—Synthesis and Characterization

The synthesis of polymer-coated gold nanoparticles with high colloidal stability is described, together with appropriate characterization techniques concerning the colloidal properties of the nanoparticles. Antibodies against vascular endothelial growth factor (VEGF) are conjugated to the surface of the nanoparticles. Antibody attachment is probed by different techniques, giving a guideline about the characterization of such conjugates. The effect of the nanoparticles on human adenocarcinoma alveolar basal epithelial cells (A549) and human umbilical vein endothelial cells (HUVECs) is probed in terms of internalization and viability assays.

Effects of VEGF and MSCs on vascular regeneration in a trauma model in rats.

In the human body, vascular injuries that are caused by trauma, vessel lumen stenosis, and occlusions are often irreversible and can lead to sequelae formation as the vessels cannot reproduce fast enough. To solve this problem, the blood flow must be returned to the region as fast as possible. The adipose tissue contains progenitor cells with angiogenic potential and can be used to resolve the issue.

Neurotoxic Effects of Fifth-Generation Dentin Adhesives on Rat Sciatic Nerve

This study evaluated the effect of the fifth-generation dentin adhesives, Single Bond (SB), Excite (EX), Prime & Bond NT (PB), and Optibond Solo (OS) on nerve conduction. Isolated rat sciatic nerves were placed between two suction electrodes in a bath containing tyrode solution. The bonding agents were brought into contact with the nerves and the evoked compound action potentials (cAPs) were recorded before and after contact with the materials. SB, EX, and PB caused total inhibition of the cAPs, with PB being the fastest (73 +/- 5.8 min). All cAPs except one in the PB group were irreversibly inhibited in the SB, EX, and PB groups. As for OS the reduction in cAP was not 50% after an application time of 200 min. Recovery of the cAPs in this group was recorded in an average time of 35 min.

Clinical performance and biocompatibility of hyaluronan-based heparin-bonded extracorporeal circuits in different risk cohorts.

This prospective randomized study compares novel hyaluronan-based heparin-bonded circuits vs. uncoated controls across EuroSCORE patient risk strata including biomaterial evaluation. Over a two-year period, 90 patients undergoing coronary artery bypass grafting were prospectively randomized to one of the two perfusion protocols: Group 1 was treated with hyaluronan-based heparin-bonded preconnected circuits (Vision HFO-GBS, Gish, CA, USA) and Group 2 with identical uncoated controls. Each group was composed of three subgroups (n=15) with respect to preoperative evaluation of low (EuroSCORE 0-2), medium (3-5) and high (6+) risk patients. Blood samples were collected after induction (T1) and heparinization (T2), 15 min after cardiopulmonary bypass start (T3), before cessation of CPB (T4), 15 min after reversal (T5), and the first postoperative day (T6). In high-risk patients, platelet counts demonstrated significant preservation at T4, T5 and leukocyte counts were lower at T5 in hyaluronan group (P<or=0.05 vs. control). C3a (ng x ml(-1)) levels were significantly lower at T3 (0.2+/-0.04 vs. 0.31+/-0.05), T4 (0.25+/-0.04 vs. 0.51+/-0.05), T5 (0.38+/-0.04 vs. 0.56+/-0.05) and interleukin-6 (pg x ml(-1)) at T4 (91+/-18 vs. 124+/-20), T5 (110+/-20 vs. 220+/-25) in coated group vs. control (P<or=0.05). Protein desorption (microalbumin) on fibers (mg x mm(-3)) was less in hyaluronan vs. control groups (P<or=0.05). Hyaluronan coating reduced platelet adhesion and cell adsorption, and modulated inflammatory response in high-risk patients.

Comparison of polymethoxyethylacrylate-coated circuits with leukocyte filtration and reduced heparinization protocol on heparin-bonded circuits in different risk cohorts.

Objectives: The relative benefits of strategic leukofiltration on polymer-coated and low-dose heparin protocol on heparin-coated circuits were studied across EuroSCORE patient risk strata for three different cohorts. Methods: In a prospective, randomized study, 270 patients undergoing coronary artery bypass grafting were allocated into three groups (n = 90): Group 1 -polymethoxyethylacrylate-coated circuits+leukocyte filters; Group 2 -polypeptide-based heparin-bonded circuits with reduced heparinization; and Group 3 -Control: uncoated circuits. Each group was further divided into three subgroups (n = 30), with respect to low- (EuroSCORE 0-2), medium- (3-5), and high- (6+) risk patients. Blood samples were collected at T1: following induction of anesthesia; T2: following heparin administration; T3: 15 min after CPB; T4: before cessation of CPB; T5: 15 min after protamine reversal; and T6: ICU. Results: In high-risk cohorts, leukocyte counts demonstrated significant differences at T4 and T5 in Group 1, and at T4 in Group 2. Platelet counts were preserved significantly better at T4 and T5 in both groups (p <0.05 versus control). Serum IL-2 and C3a levels were significantly lower at T3, T4 and T5 in Group 1, and T4 and T5 in Group 2 (p <0.05). Postoperative bleeding, respiratory support time and incidence of atrial fibrillation were lower in the study groups versus control. Cell counts on filter mesh and heparin-coated fibers/circuits were significantly higher in the high-risk cohorts versus uncoated fibers. Phagocytic capacity increased on filter mesh, especially in high-risk specimens. SEM evaluation demonstrated better preserved coated circuits. Conclusion: Leukofiltration and coating reduced platelet adhesion, protein adsorption, atrial fibrillation and reduced heparinization acted via modulation of systemic inflammatory response in high-risk groups.