Christian Viezzer

Effect of titanium surface roughness on human bone marrow cell proliferation and differentiation: an experimental study

PURPOSE To assess the proliferation and differentiation of human bone marrow-derived cells cultured on titanium surfaces with different roughness characteristics. METHODS Cells obtained from the iliac crest of an adult human donor were routinely processed and cultured on titanium surfaces of varying roughness, according to their preparation method: polishing only (smooth surface) and polishing followed by etching with HF/HNO3 for 15 and 30 minutes (rough surfaces). Surfaces were assessed using scanning electronic microscopy and profilometry. RESULTS Titanium disks etched with acid for 15 minutes allowed greater cell proliferation in all culture periods. The level of osteopontin and osteocalcin expression was increased in both acid-etched groups, which indicates an advanced stage of differentiation of cells into osteoblasts. CONCLUSIONS Increased surface roughness accelerates the differentiation of undifferentiated mesenchymal cells into osteogenic lineage cells, but does not necessarily favor cell proliferation. An intermediate surface roughness of 0.5microm (acid etching for 15 minutes) favors both initial and final cell responses.

Cytotoxicity of Silver Solder Employed in Orthodontics

OBJECTIVE To test the null hypothesis that the silver soldering employed in orthodontics is not cytotoxic for fibroblasts. MATERIALS AND METHODS This in vitro study was performed using a culture of mice fibroblasts (lineage NIH/3T3), divided into four groups (n = 10 each): control, negative control (stainless steel archwire), positive control (amalgam disks), and test group (silver soldering). After cell culture in complete Dulbecco modified eagle medium and achievement of confluence in 80%, the suspension was added to the plates of 24 wells containing the specimens and incubated in an oven at 37 degrees C for 24 hours. The plates were analyzed on an inverted light microscope, photomicrographs were obtained, and the results were recorded as response rates based on modifications of the parameters of Stanford according to the size of the diffusion halo of the toxic substance and quantity of cell lysis. RESULTS The results revealed a maximum response rate for the silver soldering group, as well as severe inhibition of cell proliferation and growth, more round cells with mostly darkened and granular aspects, suggesting lysis with cell death. A similar response was seen in the positive control group. CONCLUSION The hypothesis is rejected. The silver soldering used in orthodontics represents a highly cytotoxic material for the cells analyzed.

Efeitos das células tronco adultas de medula óssea e do plasma rico em plaquetas na regeneração e recuperação funcional nervosa em um modelo de defeito agudo em nervo perfiférico em rato

OBJECTIVES: The effects of the use of bone marrow stem cells (MSC) and platelet-rich plasma (PRP) on peripheral nerves regeneration were assessed by using an established model of sciatic nerve regeneration in rats. METHODS: A 10-mm nervous defect was reconstructed by using a silicone tube filled with MSC, PRP or both. The control group received only the silicone tube. A fifth group was also set, in which the interval was reconstructed by using a dried segment of the nerve. Motor function was tested six weeks after surgery, by means of a gait test. After motor test, the rats were anesthetized, the sciatic nerve and the tube were dried, and the transmission electronic microscopy was performed. RESULTS: The quantitative analysis shows an improved functional recovery in MSC group compared to the other groups. Nervous regeneration was reported for MSC group by means of transmission electronic microscopy with an almost full recovery of the neural anatomy. CONCLUSION: Our results suggest that the use of MSC combined with tubing technique yields a satisfactory recovery of motor function and nervous regeneration.

Effect of standard and neutral-pH peritoneal dialysis solutions upon fibroblasts proliferation

INTRODUCTION Continuous exposition of the peritoneal membrane to conventional dialysis solutions is an important risk factor for inducing structural and functional alterations. OBJECTIVE To compare in vitro mouse fibroblast NIH-3T3 cell viability after exposition to a neutral pH dialysis solution in comparison to cells exposed to a standard solution. METHODS Experimental study to compare the effects of a conventional standard or a neutral-pH, low-glucose degradation products peritoneal dialysis solution on the viability of exposed fibroblasts in cell culture. Both solutions were tested in all the commercially available glucose concentrations. Cell viability was evaluated with tetrazolium salt colorimetric assay. RESULTS Fibroblast viability was significantly superior in the neutral pH solution in comparison to control, in all three glucose concentrations (Optical density in nm-means ± SD: 1.5% 0.295 ± 0.047 vs. 0.372 ± 0.042, p < 0.001; 2.3% 0.270 ± 0.036 vs. 0.337 ± 0.051, p < 0.001; 4.25% 0.284 ± 0.037 vs. 0.332 ± 0.032, p < 0.001; control vs. neutral pH respectively, Student t Test). There was no significant difference in cell viability between the three concentrations of glucose when standard solution was used (ANOVA p = 0.218), although cell viability was higher after exposition to neutral pH peritoneal dialysis fluid at 1.5% in comparison to 2.3 and 4.25% glucose concentrations (ANOVA p = 0.008: Bonferroni 1.5% vs. 2.3% p = 0.033, 1.5% vs. 4.25% p = 0.014, 2.3% vs. 4.25% p = 1.00). CONCLUSION Cell viability was better in neutral pH dialysis solution, especially in the lower glucose concentration. A more physiological pH and lower glucose degradation products may be responsible for such results.

The Role of DNA Damage and Repair Proteins in Adipose-Derived Adult Stem Cell Differentiation in Neural- Like Cells

The development of a clinically translatable method of engineering with adipose-derived adult stem (ADAS) for reconstruction requires investigation of several components. The differentiation of ADAS cells into neuronal cells has been reported by several groups. The stringent maintenance of genomic stability in adult stem cells via anti-stress defenses and DNA repair mechanisms is particularly important because any genetic alteration can compromise the genomic stability and functionality of the cell. The main objective of this data was to examine some parameters related to DNA damage in cells submitted to the neural differentiation protocol and to understand if DNA damage can be associated to cell differentiation. The comet assay, micronucleus tests, and the cell viability assay were utilized to observe ADAS cells treated with neural induction medium. The results of our genotoxicity assays suggest that increased DNA damage observable by the comet assay was induced by neural differentiation. Emerging findings suggest that DNA damage; telomerase and DNA repair proteins play important roles in neurogenesis developing. Surprisingly we obtain evidence for an association between DNA damage and neuronal-like differentiation and hypothesize that during neural differentiation DNA damage will recruit telomerase TIP60 and MCM3, where they may function in DNA repair, chromatin remodeling and limiting DNA replication.

Biocompatibility Assessment of Poly(lactic acid) Films after Sterilization with Ethylene Oxide in Histological Study In Vivo with Wistar Rats and Cellular Adhesion of Fibroblasts In Vitro

Biomaterials must meet certain fundamental requirements for their usage in living beings, such as biocompatibility, bifunctionality, and sterilizability, without having chemical and structural changes. The biocompatibility of poly(lactic acid) (PLA) films, shaped by compression, was evaluated after sterilization by ethylene oxide by a histological in vivo test with Wistar rats and cytotoxicity in cell adhesion in vitro. The cytotoxicity test was performed by the reduction of tetrazolium salt (MTT). Thermal and chemical changes in PLA films concerning the proposed sterilization process and characteristics were not observed to evidence polymer degradation due to sterilization. The analysis of the cytotoxicity by the MTT method has shown that the sterilized PLA films are not cytotoxic. The adhesion and proliferation of fibroblasts on PLA films were homogeneously distributed over the evaluation period, showing an elongated appearance with unnumbered cytoplasmic extensions and cell-cell interactions. By examining the biocompatibility in a histological study, a mild tissue inflammation was observed with the presence of fibrosis in the samples that had been exposed for 21 days in the rats’ bodies. PLA films sterilized with ethylene oxide did not exhibit cell adhesion in vitro and toxicity to the surrounding tissue in vivo and they may be used in future in vivo testing, according to histological findings in Wistar rats in the present study.