Voluntary wheel running as a promising strategy to promote autonomic resilience to social stress in females: Vagal tone lies at the heart of the matter.

Social stress is a major risk factor for comorbid conditions including cardiovascular disease and depression. While women exhibit 2-3× the risk for these stress-related disorders compared to men, the mechanisms underlying heightened stress susceptibility among females remain largely unknown. Due to a lack in understanding of the pathophysiology underlying stress-induced comorbidities among women, there has been a significant challenge in developing effective therapeutics. Recently, a causal role for inflammation has been established in the onset and progression of comorbid cardiovascular disease/depression, with women exhibiting increased sensitivity to stress-induced immune signaling. Importantly, reduced vagal tone is also implicated in stress susceptibility, through a reduction in the vagus nerve's well-recognized anti-inflammatory properties. Thus, examining therapeutic strategies that stabilize vagal tone during stress may shed light on novel targets for promoting stress resilience among women. Recently, accumulating evidence has demonstrated that physical activity exerts cardio- and neuro-protective effects by enhancing vagal tone. Based on this evidence, this mini review provides an overview of comorbid cardiovascular and behavioral dysfunction in females, the role of inflammation in these disorders, how stress may impart its negative effects on the vagus nerve, and how exercise may act as a preventative. Further, we highlight a critical gap in the literature with regard to the study of females in this field. This review also presents novel data that are the first to demonstrate a protective role for voluntary wheel running over vagal tone and biomarkers of cardiac dysfunction in the face of social stress exposure in female rats.

From Flatland to Jupiter: Searching for Rules of Interaction Across Biological Scales.

In this future-spanning perspective, we examine how an agent-based model could be used to define general rules for interactions across biological systems and evolutionary time. To date, there have been a number of attempts to simulate the emergence of ecological communities using agent-based models of individuals that have evolving traits. Here we speculate whether it is possible to use this computational modeling to simulate self-organizing systems and, importantly, to decipher universal principles that govern biological interactions. This perspective is a thought exercise, meant to extrapolate from current knowledge to how we may make Jupiter-shot leaps to further advance the biosciences in the 21st century.

Magnetic 3D scaffolds for tissue engineering applications: bioactive glass (45S5) coated with iron-loaded hydroxyapatite nanoparticles.

Magnetic 45S5 bioactive glass (BG) based scaffolds covered with iron-loaded hydroxyapatite (Fe-HA-BG) nanoparticles were obtained and its cytotoxicity investigated. Fe-HA nanoparticles were synthesized by a wet chemical method involving the simultaneous addition of Fe2+/Fe3+ions. BG based scaffolds were prepared by the foam replica procedure and covered with Fe-HA by dip-coating. Fe-HA-BG magnetic saturation values of 0.049 emu g-1and a very low remanent magnetization of 0.01 emu g-1were observed. The mineralization assay in simulated body fluid following Kokubo's protocol indicated that Fe-HA-BG scaffolds exhibited improved hydroxyapatite formation in comparison to uncoated scaffolds at shorter immersion times. The biocompatibility of the materialin vitrowas assessed using human osteoblast-like MG-63 cell cultures and mouse bone marrow-derived stroma cell line ST-2. Overall, the results herein discussed suggest that magnetic Fe-HA coatings seem to enhance the biological performance of 45S5 BG based scaffolds. Thus, this magnetic Fe-HA coated scaffold is an interesting system for bone tissue engineering applications and warrant further investigation.

High-fat diet induces neuroinflammation and reduces the serotonergic response to escitalopram in the hippocampus of obese rats.

Clinical studies indicate that obese individuals have an increased risk of developing co-morbid depressive illness and that these patients have reduced responses to antidepressant therapy, including selective serotonin reuptake inhibitors (SSRIs). Obesity, a condition of chronic mild inflammation including obesity-induced neuroinflammation, is proposed to contribute to decreases in synaptic concentrations of neurotransmitters like serotonin (5HT) by decreasing 5HT synthesis in the dorsal raphe nucleus (DRN) and/or affecting 5HT reuptake in DRN target regions like the hippocampus. In view of these observations, the goal of the current study was to examine inflammatory markers and serotonergic dynamics in co-morbid obesity and depression. Biochemical and behavioral assays revealed that high-fat diet produced an obesity and depressive-like phenotype in one cohort of rats and that these changes were marked by increases in key pro-inflammatory cytokines in the hippocampus. In real time using fast scan cyclic voltammetry (FSCV), we observed no changes in basal levels of hippocampal 5HT; however responses to escitalopram were significantly impaired in the hippocampus of obese rats compared to diet resistant rats and control rats. Further studies revealed that these neurochemical observations could be explained by increases in serotonin transporter (SERT) expression in the hippocampus driven by elevated neuroinflammation. Collectively, these results demonstrate that obesity-induced increases in neuroinflammation adversely affect SERT expression in the hippocampus of obese rats, thereby providing a potential synaptic mechanism for reduced SSRI responsiveness in obese subjects with co-morbid depressive illness.

Bioactive glass (45S5)-based 3D scaffolds coated with magnesium and zinc-loaded hydroxyapatite nanoparticles for tissue engineering applications.

Bioactive glass (BG)-based scaffolds of 45S5 composition covered with hydroxyapatite nanoparticles loaded with Mg2+, Zn2+ and, both Mg2+ and Zn2+ ions, were developed and tested as materials for tissue engineering applications. The scaffolds were prepared by the foam replica technique and mono- and bi-metal loaded and unloaded hydroxyapatite nanoparticles (HA, Zn-HA, Mg-HA and Mg-Zn-HA) were obtained by an adaptation of the wet chemical deposition method. Coating of BG with these nanoparticles was performed by dip-coating to obtain HA-BG, Zn-HA-BG, Mg-HA-BG and Mg-Zn-HA-BG scaffolds. As predictor of the bone bonding ability of the produced scaffolds, in this study we investigated the formation of an apatite layer on the scaffold surfaces in the presence of simulated body fluid. The cytotoxicity and osteogenic properties of the materials in vitro was evaluated using human osteoblast-like MG-63 cell cultures. The mineralization assay following Kokubo's protocol indicated that bi-metal loaded Mg-Zn-HA-BG scaffolds exhibited higher/faster bioactivity than mono-metal loaded scaffolds while mineralization of HA-BG, Zn-HA-BG and Mg-HA-BG was similar to that of uncoated scaffolds. Moreover, an increase of proliferation of MG-63 cells after 48 h and 7 days was measured by BrdU assays for Mg-Zn-HA-BG scaffolds. In agreement with these results, SEM images confirmed increased interaction between these scaffolds and cells, in comparison to that observed for mono-metal-loaded HA-coated scaffolds. Altogether, the obtained results suggest that nanocrystalline Mg-Zn-HA coatings enhance the biological performance of standard scaffolds of 45S5 BG composition. Thus these novel ion doped HA coated scaffolds are attractive systems for bone tissue engineering.

Insulin resistance and hippocampal dysfunction: Disentangling peripheral and brain causes from consequences.

In the periphery insulin plays a critical role in the regulation of metabolic homeostasis by stimulating glucose uptake into peripheral organs. In the central nervous system (CNS), insulin plays a critical role in the formation of neural circuits and synaptic connections from the earliest stages of development and facilitates and promotes neuroplasticity in the adult brain. Beyond these physiological roles of insulin, a shared feature between the periphery and CNS is that decreases in insulin receptor activity and signaling (i.e. insulin resistance) contributes to the pathological consequences of type 2 diabetes (T2DM) and obesity. Indeed, clinical and preclinical studies illustrate that CNS insulin resistance elicits neuroplasticity deficits that lead to decreases in cognitive function and increased risk of neuropsychiatric disorders. The goals of this review are to provide an overview of the literature that have identified the neuroplasticity deficits observed in T2DM and obesity, as well as to discuss the potential causes and consequences of insulin resistance in the CNS, with a particular focus on how insulin resistance impacts hippocampal neuroplasticity. Interestingly, studies that have examined the effects of hippocampal-specific insulin resistance illustrate that brain insulin resistance may impair neuroplasticity independent of peripheral insulin resistance, thereby supporting the concept that restoration of brain insulin activity is an attractive therapeutic strategy to ameliorate or reverse cognitive decline observed in patients with CNS insulin resistance such as T2DM and Alzheimer's Disease.

Insulin Resistance as a Therapeutic Target in the Treatment of Alzheimer's Disease: A State-of-the-Art Review.

Research in animals and humans has shown that type 2 diabetes and its prodromal state, insulin resistance, promote major pathological hallmarks of Alzheimer's disease (AD), such as the formation of amyloid plaques and neurofibrillary tangles (NFT). Worrisomely, dysregulated amyloid beta (Aß) metabolism has also been shown to promote central nervous system insulin resistance; although the role of tau metabolism remains controversial. Collectively, as proposed in this review, these findings suggest the existence of a mechanistic interplay between AD pathogenesis and disrupted insulin signaling. They also provide strong support for the hypothesis that pharmacologically restoring brain insulin signaling could represent a promising strategy to curb the development and progression of AD. In this context, great hopes have been attached to the use of intranasal insulin. This drug delivery method increases cerebrospinal fluid concentrations of insulin in the absence of peripheral side effects, such as hypoglycemia. With this in mind, the present review will also summarize current knowledge on the efficacy of intranasal insulin to mitigate major pathological symptoms of AD, i.e., cognitive impairment and deregulation of Aß and tau metabolism.

Intranasal insulin in Alzheimer's disease: Food for thought.

Accumulating evidence suggests that disrupted brain insulin signaling promotes the development and progression of Alzheimer's disease (AD), driving clinicians to target this circuitry. While both traditional and more modern antidiabetics show promise in combating insulin resistance, intranasal insulin appears to be the most efficient method of boosting brain insulin. Furthermore, intranasal delivery elegantly avoids adverse effects from peripheral insulin administration. However, there remain significant open questions regarding intranasal insulin's efficacy, safety, and potential as an adjunct or mono-therapy. Thus, this review aims to critically evaluate the present evidence and future potential of intranasal insulin as a meaningful treatment for AD. This article is part of the Special Issue entitled 'Metabolic Impairment as Risk Factors for Neurodegenerative Disorders.'

Is there any difference in the biological impact of soluble and insoluble degradation products of iron-containing biomaterials?

The interactions that could be built between the biomaterials and tissue- microenvironments are very complex, especially in case of degradable metals that generate a broad variety of degradation products. The interfacial problems are particularly relevant for Fe-based materials that have been proposed for the development of biodegradable implants. The cell metabolism could be affected by the accumulation of insoluble Fe-containing degradation products that has been observed in vitro and in vivo as a coarse granular brownish material around the implant. However, the relative importance of each Fe-species (soluble and insoluble) on the cellular behavior of the surrounding cells, particularly on the generation of reactive species (RS), is not completely elucidated. The aim of this study is to evaluate the processes occurring at the Fe-biomaterial/cells interfacial region, and to discriminate the effects of soluble and insoluble corrosion products released by the bulk metal (Fe- microparticles (Fe0p) or Fe0 ring) on the adjacent cells, mainly in relation to RS generation. With this purpose Fe0p and Fe0 ring were incubated with fibroblast cells (BALB/c 3T3 line) for 24 and 48h periods. Then different techniques were used, such as the dichlorofluorescein diacetate assay (DCFH2-DA) for detection of RS, acridine orange dye for cell viability, total protein content determinations, Prussian Blue staining and TEM observations. To individualize the effects of soluble and insoluble species, independent experiments with Fe3+-salts were performed. Overall data indicate that RS generation by cells exposed to the degradation products of Fe-based biomaterials is more dependent on the presence of insoluble products than on soluble Fe species.

Leptin resistance and hippocampal behavioral deficits.

The adipocyte-derived hormone leptin is an important regulator of body weight and metabolism through activation of brain leptin receptors expressed in regions such as the hypothalamus. Beyond these well described and characterized activities of leptin in the hypothalamus, it is becoming increasingly clear that the central activities of leptin extend to the hippocampus. Indeed, leptin receptors are expressed in the hippocampus where these receptors are proposed to mediate various aspects of hippocampal synaptic plasticity that ultimately impact cognitive function. This concept is supported by studies demonstrating that leptin promotes hippocampal-dependent learning and memory, as well as studies indicating that leptin resistance is associated with deficits in hippocampal-dependent behaviors and in the induction of depressive-like behaviors. The effects of leptin on cognitive/behavioral plasticity in the hippocampus may be regulated by direct activation of leptin receptors expressed in the hippocampus; additionally, leptin-mediated activation of synaptic networks that project to the hippocampus may also impact hippocampal-mediated behaviors. In view of these previous observations, the goal of this review will be to discuss the mechanisms through which leptin facilitates cognition and behavior, as well as to dissect the loci at which leptin resistance leads to impairments in hippocampal synaptic plasticity, including the development of cognitive deficits and increased risk of depressive illness in metabolic disorders such as obesity and type 2 diabetes mellitus (T2DM).

Time-Lapse Evaluation of Interactions Between Biodegradable Mg Particles and Cells.

Mg-based implants have promising applications as biodegradable materials in medicine for orthopedic, dental, and cardiovascular therapies. During wear and degradation microdebris are released. Time-lapse multidimensional microscopy (MM) is proposed here as a suitable tool to follow, in fixed intervals over 24-h periods, the interaction between cells and particles. Results of MM show interactions of macrophages (J774) with the magnesium particles (MgPa) that led to modifications of cell size and morphology, a decrease in duplication rate, and cell damage. Corrosion products were progressively formed on the surface of the particles and turbulence was generated due to hydrogen development. Changes were more significant after treating MgPa with potassium fluoride. In order to complement MM observations, membrane damage as detected by a lactase dehydrogenase (LDH) assay and mitochondrial activity as detected by a WST-1 assay with macrophages and osteoblasts (MC3T3-E1) were compared. A more significant concentration-dependent effect was detected for macrophages exposed to MgPa than for osteoblasts. Accordingly, complementary data showed that viability and cell cycle seem to be more altered in macrophages. In addition, protein profiles and expression of proteins associated with the adhesion process changed in the presence of MgPa. These studies revealed that time-lapse MM is a helpful tool for monitoring changes of biodegradable materials and the biological surrounding in real time and in situ. This information is useful in studies related to biodegradable biomaterials.

Degradation of bioabsorbable Mg-based alloys: Assessment of the effects of insoluble corrosion products and joint effects of alloying components on mammalian cells.

This work is focused on the processes occurring at the bioabsorbable metallic biomaterial/cell interfaces that may lead to toxicity. A critical analysis of the results obtained when degradable metal disks (pure Mg and rare earth-containing alloys (ZEK100 alloys)) are in direct contact with cell culture and those obtained with indirect methods such as the use of metal salts and extracts was made. Viability was assessed by Acridine Orange dye, neutral red and clonogenic assays. The effects of concentration of corrosion products and possible joint effects of the binary and ternary combinations of La, Zn and Mg ions, as constituents of ZEK alloys, were evaluated on a mammalian cell culture. In all cases more detrimental effects were found for pure Mg than for the alloys. Experiments with disks showed that gradual alterations in pH and in the amount of corrosion products were better tolerated by cells and resulted in higher viability than abrupt changes. In addition, viability was dependent on the distance from the source of ions. Experiments with extracts showed that the effect of insoluble degradation products was highly detrimental. Indirect tests with Zn ions revealed that harmful effects may be found at concentrations ≥ 150 µM and at ≥ 100 µM in mixtures with Mg. These mixtures lead to more deleterious effects than single ions. Results highlight the need to develop a battery of tests to evaluate the biocompatibility of bioabsorbable biomaterials.

Hippocampal Insulin Resistance Impairs Spatial Learning and Synaptic Plasticity.

Insulin receptors (IRs) are expressed in discrete neuronal populations in the central nervous system, including the hippocampus. To elucidate the functional role of hippocampal IRs independent of metabolic function, we generated a model of hippocampal-specific insulin resistance using a lentiviral vector expressing an IR antisense sequence (LV-IRAS). LV-IRAS effectively downregulates IR expression in the rat hippocampus without affecting body weight, adiposity, or peripheral glucose homeostasis. Nevertheless, hippocampal neuroplasticity was impaired in LV-IRAS-treated rats. High-frequency stimulation, which evoked robust long-term potentiation (LTP) in brain slices from LV control rats, failed to evoke LTP in LV-IRAS-treated rats. GluN2B subunit levels, as well as the basal level of phosphorylation of GluA1, were reduced in the hippocampus of LV-IRAS rats. Moreover, these deficits in synaptic transmission were associated with impairments in spatial learning. We suggest that alterations in the expression and phosphorylation of glutamate receptor subunits underlie the alterations in LTP and that these changes are responsible for the impairment in hippocampal-dependent learning. Importantly, these learning deficits are strikingly similar to the impairments in complex task performance observed in patients with diabetes, which strengthens the hypothesis that hippocampal insulin resistance is a key mediator of cognitive deficits independent of glycemic control.

Cytotoxicity of corrosion products of degradable Fe-based stents: relevance of pH and insoluble products.

Fe-based biodegradable metallic materials (Fe-BMMs) have been proposed for cardiovascular applications and are expected to disappear via corrosion after an appropriate period. However, in vivo studies showed that Fe ions release leads to accumulation of orange and brownish insoluble products at the biomaterial/cell interface. As an additional consequence, sharp changes in pH may affect the biocompatibility of these materials. In the present work, the experimental protocols were designed with the aim of evaluating the relative importance that these factors have on biocompatibility evaluation of BMMs. Mitochondrial activity (MTT assay) and thiobarbituric acid reactive substances (TBARS) assay on mammalian cells, exposed to 1-5 mM of added Fe3+ salt, were assessed and compared with results linked exclusively to pH effects. Soluble Fe concentration in culture medium and intracellular Fe content were also determined. The results showed that: (i) mitochondrial activity was affected by pH changes over the entire range of concentrations of added Fe3+ assayed, (ii) at the highest added Fe3+ concentrations (≥3 mM), precipitation was detected and the cells were able to incorporate the precipitate, that seems to be linked to cell damage, (iii) the extent of precipitation depends on the Fe/protein concentration ratio; and (iv) lipid peroxidation products were detected over the entire range of concentrations of added Fe3+. Hence, a new approach opens in the biocompatibility evaluation of Fe-based BMMs, since the cytotoxicity would not be solely a function of released (and soluble) ions but of the insoluble degradation product amount and the pH falling at the biomaterial/cell interface. The concentration of Fe-containing products at the interface depends on diffusional conditions in a very complex way that should be carefully analyzed in the future.

Stress as a one-armed bandit: Differential effects of stress paradigms on the morphology, neurochemistry and behavior in the rodent amygdala.

Neuroplasticity may be defined as the ability of the central nervous system (CNS) to respond to changes in the internal and external environment and it is well established that some stimuli have the ability to facilitate or impair neuroplasticity depending on the pre-existing milieu. A classic example of a stimulus that can both facilitate and impair neuroplasticity is stress. Indeed, the ability of CNS to respond to acute stress is often dependent upon the prior stress history of the individual. While responses to acute stress are often viewed as adaptive in nature, stress reactivity in subjects with prior chronic stress experiences are often linked to neuropsychiatric disorders, including major depressive disorder, post-traumatic stress disorder (PTSD) and anxiety. In rodent studies, chronic stress exposure produces structural and functional alterations in the hippocampus and medial prefrontal cortex that are consistent across different types of stress paradigms. Conversely, the amygdala appears to exhibit differential structural and functional responses to stress that are dependent on a variety of factors, including the type of stressor performed and the duration of the stress paradigm. This is most evident in output measures including morphological analysis of amygdala neurons, measurement of glutamatergic tone in amygdalar subdivisions and the analysis of amygdala-centric behaviors. Accordingly, this review will provide an overview of the effects of stress on the structural and functional plasticity of the rodent amygdala, especially in relation to the differential effects of repeated or chronic stress paradigms on dendritic architecture, neurochemistry of the glutamatergic system and behavior.

Cellular response to rare earth mixtures (La and Gd) as components of degradable Mg alloys for medical applications.

Rare earth (RE) elements have been proposed to improve the corrosion resistance of degradable Mg alloys for medical applications. However, good biocompatibility of the elements released by Mg alloys during degradation is essential for their use in implants. Most studies are focused on material science and engineering aspects, but the effects of ions released at the biological interface are not frequently addressed. The aim of this study was to contribute to the knowledge of in vitro toxicological effects of two RE Mg-alloying elements, La and Gd, as individual ions and in mixtures with and without Mg ions. Different combinations (Mg+Gd, Mg+La, and Mg+Gd+La) were used to evaluate their possible synergistic effects on CHO-K1 cells. Two sets of experiments were designed to assess (1) the cyto-genotoxic effect of La and Gd ions by neutral red (NR) technique, Reduction of tetrazolium salt (MTT), Viability with Acridine Orange staining, Clonogenic test, and Comet assay; and, (2) the possible synergistic toxicological effect of La and Gd ions in mixtures, and the influence of osmolarity increase on cellular response. Cytotoxic effects of RE were found at concentrations ≥200 µM RE while DNA damage was detected for doses ≥1500 µM and ≥1600 µM for La and Gd, respectively. When mixtures of ions were evaluated, neither synergistic cytotoxic effects nor biological damage related to osmolarity increase were detected.

Dietary restriction reverses obesity-induced anhedonia.

Obesity-induced changes in the metabolic and endocrine milieu elicit deficits in neuroplasticity, including increased risk for development of neuropsychiatric disorders such as depressive illness. We previously demonstrated that downregulation of hypothalamic insulin receptors (hypo-IRAS) elicits a phenotype that is consistent with features of the metabolic syndrome (MetS) and that rats with this phenotype exhibit deficits in neuronal plasticity, including depressive-like behaviors such as anhedonia. Since food restriction paradigms effectively inhibit obesity-induced neuroplasticity deficits, the aim of the current study was to determine whether food restriction could reverse obesity-induced anhedonia in hypo-IRAS rats. Compared to hypo-IRAS rats provided ad lib food access, food restriction paradigms that were initiated either prior to increases in body weight or following development of the MetS/obesity phenotype effectively restored sucrose intake in hypo-IRAS rats. Moreover, food restriction paradigms were able to prevent and reverse the changes in the endocrine/metabolic/inflammatory milieu observed in hypo-IRAS, such as increases in plasma leptin and triglyceride levels and increases in pro-inflammatory cytokines such as IL-1α, IL-6 and C-reactive protein (CRP). Collectively, these results demonstrate that obesity-induced anhedonia is a reversible process and identify some potential mechanistic mediators that may be responsible for co-morbid depression in obesity.

Synergistic cytotoxic effects of ions released by zinc-aluminum bronze and the metallic salts on osteoblastic cells.

The use of copper-based alloys for fixed dental crowns and bridges is increasingly widespread in several countries. The aim of this work is to study the dissolution of a zinc-aluminum-bronze and the cytotoxic effects of the ions released on UMR-106 osteoblastic cell line. Two sources of ions were used: (1) ions released by the metal alloy immersed in the cell culture and (2) salts of the metal ions. Conventional electrochemical techniques, atomic absorption spectroscopy [to obtain the average concentration of ions (AC) in solution], and energy dispersive X-ray (EDX) spectroscopy analysis were used to study the corrosion process. Corrosion tests revealed a strong influence of the composition of the electrolyte medium and the immersion time on the electrochemical response. The cytotoxicity was evaluated with (a) individual ions, (b) combinations of two ions, and (c) the mixture of all the ions released by a metal disc of the alloy. Importantly, synergistic cytotoxic effects were found when Al-Zn ion combinations were used at concentration levels lower than the cytotoxic threshold values of the individual ions. Cytotoxic effects in cells in the vicinity of the metal disc were also found. These results were interpreted considering synergistic effects and a diffusion controlled mechanism that yields to concentration levels, in the metal surroundings, several times higher than the measured AC value.

Citrate-capped silver nanoparticles showing good bactericidal effect against both planktonic and sessile bacteria and a low cytotoxicity to osteoblastic cells.

A common problem with implants is that bacteria can form biofilms on their surfaces, which can lead to infection and, eventually, to implant rejection. An interesting strategy to inhibit bacterial colonization is the immobilization of silver (Ag) species on the surface of the devices. The aim of this paper is to investigate the action of citrate-capped silver nanoparticles (AgNPs) on clinically relevant Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria in two different situations: (i) dispersed AgNPs (to assess the effect of AgNPs against planktonic bacteria) and (ii) adsorbed AgNPs on titanium (Ti) substrates, a material widely used for implants (to test their effect against sessile bacteria). In both cases, the number of surviving cells was quantified. The small amount of Ag on the surface of Ti has an antimicrobial effect similar to that of pure Ag surfaces. We have also investigated the capability of AgNPs to kill planktonic bacteria and their cytotoxic effect on UMR-106 osteoblastic cells. The minimum bactericidal concentration found for both strains is much lower than the AgNP concentration that leads to cytotoxicity to osteoblasts. Planktonic P. aeruginosa show a higher susceptibility to Ag than S. aureus, which can be caused by the different wall structures, while for sessile bacteria, similar results are obtained for both strains. This can be explained by the presence of extracellular polymeric substances in the early stages of P. aeruginosa biofilm formation. Our findings can be important to improving the performance of Ti-based implants because a good bactericidal action is obtained with very small quantities of Ag, which are not detrimental to the cells involved in the osseointegration process.