Differential response of human gingival fibroblasts to titanium- and titanium-zirconium-modified surfaces

BACKGROUND AND OBJECTIVE

Gingival fibroblasts are responsible for the constant adaptation, wound healing and regeneration of gingival connective tissue. New titanium-zirconium (TiZr) abutment surfaces have been designed to improve soft tissue integration and reduce implant failure compared with titanium (Ti). The aim of the present study was first to characterize a primary human gingival fibroblast (HGF) model and secondly to evaluate their differential response to Ti and TiZr polished (P), machined (M) and machined + acid-etched (modMA) surfaces, respectively.

MATERIAL AND METHODS

HGF were cultured on tissue culture plastic or on the different Ti and TiZr surfaces. Cell morphology was evaluated through confocal and scanning electron microscopy. A wound healing assay was performed to evaluate the capacity of HGF to close a scratch. The expression of genes was evaluated by real-time RT-PCR, addressing: (i) extracellular matrix organization and turnover; (ii) inflammation; (iii) cell adhesion and structure; and (iv) wound healing. Finally, cells on Ti/TiZr surfaces were immunostained with anti-ITGB3 antibodies to analyze integrin β3 production. Matrix metalloproteinase-1 (MMP1) and inhibitor of metallopeptidases-1 (TIMP1) production were analyzed by enzyme-linked immunosorbent assays.

RESULTS

On tissue culture plastic, HGF showed no differences between donors on cell proliferation and on the ability for wound closure; α-smooth muscle actin was overexpressed on scratched monolayers. The differentiation profile showed increased production of extracellular matrix components. Ti and TiZr showed similar biocompatibility with HGF. TiZr increased integrin-β3 mRNA and protein levels, compared with Ti. Cells on TiZr surfaces showed higher MMP1 protein than Ti surfaces, although similar TIMP1 protein production. In this in vitro experiment, P and M surfaces from both Ti and TiZr showed better HGF growth than modMA.

CONCLUSION

Taking into account the better mechanical properties and bioactivity of TiZr compared with Ti, the results of the present study show that TiZr is a potential clinical candidate for soft tissue integration and implant success.

Effect of alginate hydrogel containing polyproline-rich peptides on osteoblast differentiation

Polyproline-rich synthetic peptides have previously been shown to induce bone formation and mineralization in vitro and to decrease bone resorption in vivo. Alginate hydrogel formulations containing these synthetic peptides (P2, P5, P6) or Emdogain® (EMD) were tested for surface coating of bone implants. In an aqueous environment, the alginate hydrogels disclosed a highly compact structure suitable for cell adhesion and proliferation. Lack of cytotoxicity of the alginate-gel coating containing peptides was tested in MC3T3-E1 cell cultures. In the present study, relative mRNA expression levels of integrin alpha 8 were induced by P5 compared to untreated alginate gel, and osteopontin mRNA levels were increased after 21 days of culture by treatment with synthetic peptides or EMD compared to control. Further, in agreement with previous results when the synthetic peptides were administered in the culture media, osteocalcin mRNA was significantly upregulated after long-term treatment with the formulated synthetic peptides compared to untreated and EMD alginate gel. These results indicate that the alginate gel is a suitable carrier for the delivery of synthetic peptides, and that the formulation is promising as biodegradable and biocompatible coating for bone implants.

The glutamine 27 glutamic acid polymorphism of the beta2-adrenoceptor gene is associated with abdominal obesity and greater risk of impaired glucose tolerance in men but not in women: a population-based study in Spain

OBJECTIVE

Given the important role of the beta2-adrenoceptor (beta2-AR) in lipid mobilization and the lack of studies in Southern European countries, the aim of this study was to investigate the role of the glutamine 27 glutamic acid (Gln27Glu) beta2-AR polymorphism in the susceptibility to obesity and its metabolic complications in a population-based nationwide multicentre study in Spain, especially focusing on the hypothetical influence of gender.

DESIGN

Cross-sectional population-based study.

PATIENTS

We studied 666 nonrelated adults (47.9% men and 52.1% women), aged 35-64 years, chosen randomly from a nationwide population-based survey of obesity, and related conditions including insulin resistance and cardiovascular risk factors.

MEASUREMENTS

Body mass index (BMI), waist-to-hip ratio (WHR), sagittal abdominal diameter (SAD), systolic and diastolic blood pressure, fasting and 2-h post-glucose load glycaemic levels, total cholesterol, high density lipoprotein (HDL)- and low density lipoprotein (LDL)-cholesterol, triglycerides, insulin, proinsulin and leptin plasma levels were measured. Beta2-AR Gln27Glu genotypes were determined by restriction fragment length polymorphism (RFLP)-polymerase chain reaction (PCR).

RESULTS

Glu27 homozygous obese men had significantly higher BMI and SAD mean values than both heterozygous and Gln27 homozygous obese men. Two-hour post-load plasma glucose concentration was higher in Glu27 homozygous than in Gln27 homozygous in the whole population and only in men when stratified by gender. No differences according to the genotype were found for the rest of the parameters studied, including homeostasis model assessment (HOMA), insulin, proinsulin and leptin levels, but for total and LDL-cholesterol these increased in men. We did not find differences in the anthropometrical and biochemical parameters according to the genotype in women. Multivariate logistic regression analysis showed that Glu27 homozygosity after adjustment for SAD was associated with type 2 diabetes mellitus.

CONCLUSIONS

Our results suggest that the glutamic acid 27 allele of the beta2-adrenoceptor may be a risk factor in men but not in women for the accumulation of visceral fat and for its association with the development of type 2 diabetes mellitus.

Carboxypeptidase E and thrombospondin-1 are differently expressed in subcutaneous and visceral fat of obese subjects

The aim of this study was to identify candidate genes for visceral obesity by screening for genes strongly differentially expressed between human subcutaneous and visceral adipose depots. A cDNA microarray with human adipose-derived cDNAs was used as an initial screening to identify genes that are potentially differentially expressed between human subcutaneous and visceral abdominal fat tissues. For the two best candidates, carboxypeptidase E (CPE) and thrombospondin-1 (THBS1) (EST N72406), real-time RT-PCR was performed to confirm their depot specific expression in extremely obese individuals. Both genes appeared to be strongly differentially expressed, having a higher expression in the visceral depot than in the subcutaneous one. For THBS1, the difference in expression between the depots was greater in women than in men. The involvement of CPE and THBS1 in obesity allows us to suggest that the physiological processes controlled by these genes contribute to depot and gender-related differences in the metabolic complications of obesity.

[Genetic polymorphisms and new perspectives in the prevention and treatment of obesity]

The prevalence of obesity has increased to an extraordinary degree, especially over the last three decades, so that if these trends persist, practically all of the adult population would be obese in the course of only two generations. On the basis of family and adoption studies, it has been estimated that the genetic component in obesity ranges from 20% to 80%. Thus, the most common forms of obesity would depend on the interaction of multiple genes as well as on the influence of various environmental factors, such as eating behaviour and lifestyle. Although none of these genes potentially involved in the control of body weight seems to be directly responsible for the syndrome, there have been reports of interesting associations between polymorphisms of certain candidate genes and obesity or its metabolic complications. The studies into associations between genotypes and obese phenotype have increased over the last few years and have basically focussed on the genes involved in the control of the energy balance, giving rise to a whole series of results which might constitute the basis for extremely interesting strategies for the prevention and treatment of this serious problem.