Effects of cysteamine and cystamine on the sonochemical accumulation of hydrogen peroxide--implications for their mechanisms of action in ultrasound-exposed cells

A Case Series With Cysteamine-Isobionicamide Complex: Clues for Skin-Rejuvenating Activity

BACKGROUND

Skin aging is inevitable. Wrinkles, skin texture abnormalities, senile hyperpigmentation, loss of skin tone, dryness, atrophy, and telangiectasias represent some of the hallmarks of aged skin. Skin rejuvenation can be addressed by topical therapies, such as topical retinoids and antioxidants or physical modalities with energy-based devices, all providing acceptable outcomes. In this case series, we aimed to test the rejuvenating potential of the combination of cysteamine (a naturally occurring antioxidant) and isobionicamide (a derivative of the anti-aging molecule niacinamide) applied topically.

METHODS

Healthy male and female patients (N = 7) aged between 25 and 70 years and having Fitzpatrick skin types I-VI were recruited. Topical application of a cysteamine-isobionicamide formula was done once daily. Treatment lasted for 16 weeks. Clinical high-resolution photos were acquired using LifeViz 3D at recruitment and after 16 weeks. Blinded dermatological examinations and scoring were performed. Self-assessment and quality of life (QoL) questionnaires were collected.

RESULTS

Clinical photos showed improvement in skin luminosity, increased evenness of skin tone, and reduction of fine wrinkles as well as hyperpigmentation. Patients as well as clinical investigators blinded to the chronology of photos observed the improvements in skin texture, luminosity, and radiance, the brightening of the dark spots, as well as the reduction of both number and volume of wrinkles after 16 weeks of daily application. Furthermore, a significant improvement in patients' quality of life was recorded.

CONCLUSION

This case series represents the first evidence that topical application of cysteamine isobionic-amide complex could be considered as a safe and effective option in the reversal of skin photoaging.

The promising interplay between sonodynamic therapy and nanomedicine

Sonodynamic therapy (SDT) is a non-invasive approach for cancer treatment in which chemical compounds, named sonosensitizers, are activated by non-thermal ultrasound (US), able to deeply penetrate into the tissues. Despite increasing interest, the underlying mechanisms by which US triggers the sonosensitizer therapeutic activity are not yet clearly elucidate, slowing down SDT clinical application. In this review we will discuss the main mechanisms involved in SDT with particular attention to the sonosensitizers involved for each described mechanism, in order to highlight how much important are the physicochemical properties of the sonosensitizers and their cellular localization to predict their bioeffects. Moreover, we will also focus our attention on the pivotal role of nanomedicine providing the sonodynamic anticancer approach with the ability to shape US-responsive agents to enhance specific sonodynamic effects as the sonoluminescence-mediated anticancer effects. Indeed, SDT is one of the biomedical fields that has significantly improved in recent years due to the increased knowledge of nanosized materials. The shift of the nanosystem from a delivery system for a therapeutic agent to a therapeutic agent in itself represents a real breakthrough in the development of SDT. In doing so, we have also highlighted potential areas in this field, where substantial improvements may provide a valid SDT implementation as a cancer therapy.

Enhancement of Fluorescent Probe Penetration into Tumors In Vivo Using Unseeded Inertial Cavitation

Ultrasound-induced cavitation has found many applications in the field of cancer therapy. One of its beneficial effects is the enhancement of drug intake by tumor cells. Our group has developed a device that can create and control unseeded cavitation in tissue using ultrasound. We conducted experiments on tumor-bearing mice using our device to assess the impact of sonication on the penetration of fluorescent probes into tumor cells. We studied the influence of pressure level, timing of sonication and sonication duration on treatment efficiency. Our results indicate that fluorescent probes penetrate better into tumors exposed to ultrasound. The best results revealed an increase in penetration of 61% and were obtained when sonicating the tumor in presence of the probes with a peak negative pressure at focus of 19 MPa. At this pressure level, the treatment generated only minor skin damage. Treatments could be significantly accelerated as equivalent enhanced penetration of probes was achieved when multiplying the initial raster scan speed by a factor of four.

Photobleaching lifetimes of cyanine fluorophores used for single-molecule Förster resonance energy transfer in the presence of various photoprotection systems

Lengthening smFRET lifetimes: We investigated various photoprotection system combinations to find the combination that optimally extended the photobleach lifetime of a Cy3/Cy5 smFRET pair attached to a DNA hairpin in a single-molecule environment. We found that the glucose/glucose oxygen-scavenging solution in combination with redox-based photostabilization solutions yielded the longest average photobleaching lifetimes.

Involvement of reactive oxygen species in sonodynamically induced apoptosis using a novel porphyrin derivative

In this study, we investigated the induction of apoptosis by ultrasound in the presence of the novel porphyrin derivative DCPH-P-Na(I). HL-60 cells were exposed to ultrasound for up to 3 min in the presence and absence of DCPH-P-Na(I), and the induction of apoptosis was examined by analyzing cell morphology, DNA fragmentation, and caspase-3 activity. Reactive oxygen species were measured by means of ESR and spin trapping technique. Cells treated with 8 μM DCPH-P-Na(I) and ultrasound clearly showed membrane blebbing and cell shrinkage, whereas significant morphologic changes were not observed in cells exposed to either ultrasound or DCPH-P-Na(I) alone. Also, DNA ladder formation and caspase-3 activation were observed in cells treated with both ultrasound and DCPH-P-Na(I) but not in cells treated with ultrasound or DCPH-P-Na(I) alone. In addition, the combination of DCPH-P-Na(I) and the same acoustical arrangement of ultrasound substantially enhanced nitroxide generation by the cells. Sonodynamically induced apoptosis, caspase-3 activation, and nitroxide generation were significantly suppressed by histidine. These results indicate that the combination of ultrasound and DCPH-P-Na(I) induced apoptosis in HL-60 cells. The significant reduction in sonodynamically induced apoptosis, nitroxide generation, and caspase-3 activation by histidine suggests active species such as singlet oxygen are important in the sonodynamic induction of apoptosis. These experimental results support the possibility of sonodynamic treatment for cancer using the induction of apoptosis.

Utilization of the ferrous sulfate (Fricke) dosimeter for evaluating the radioprotective potential of cystamine: experiment and Monte Carlo simulation

Cystamine, an organic disulfide (RSSR), is among the best of the known radiation-protective compounds and has been used to protect normal tissues in clinical radiation therapy. Recently, it has also proved to be beneficial in the treatment of disorders of the central nervous system in animal models. However, the underlying mechanism of its action at the chemical level is not yet well understood. The present study aims at using the ferrous sulfate (Fricke) dosimeter to quantitatively evaluate, both experimentally and theoretically, the radioprotective potential of this compound. The well-known radiolysis of the Fricke dosimeter by (60)Co γ rays or fast electrons, based on the oxidation of ferrous ions to ferric ions by the oxidizing species (•)OH, HO(2)(•), and H(2)O(2) produced in the radiolytic decomposition of water, forms the basis for our method. The presence of cystamine in Fricke dosimeter solutions during irradiation prevents the radiolytic oxidation of Fe(2+) and leads to decreased ferric yields (or G values). The observed decrease in G(Fe(3+)) increases upon increasing the concentration of the disulfide compound over the range 0-0.1 M under both aerated and deaerated conditions. To help assess the basic radiation-protective mechanism of this compound, a full Monte Carlo computer code is developed to simulate in complete detail the radiation-induced chemistry of the studied Fricke/cystamine solutions. Benefiting from the fact that cystamine is reasonably well characterized in terms of radiation chemistry, this computer model proposes reaction mechanisms and incorporates specific reactions describing the radiolysis of cystamine in aerated and deaerated Fricke solutions that lead to the observable quantitative chemical yields. Results clearly indicate that the protective effect of cystamine originates from its radical-capturing ability, which allows this compound to act by competing with the ferrous ions for the various free radicals--especially (•)OH radicals and H(•) atoms--formed during irradiation of the surrounding water. Most interestingly, our simulation modeling also shows that the predominant pathway in the oxidation of cystamine by (•)OH radicals involves an electron-transfer mechanism, yielding RSSR(•+) and OH(-). A very good agreement is found between calculated G(Fe(3+)) values and experiment. This study concludes that Monte Carlo simulations represent a very efficient method for understanding indirect radiation damage at the molecular level.

Reactive oxygen species and DNA damage after ultrasound exposure

The aim of this work was to detect the formation of hydrogen peroxide and hydroxyl radicals after ultrasound (US) exposure and test the hypothesis that reactive oxygen species induced by ultrasound can contribute to DNA damage. Formation of reactive oxygen species was observed in incubated medium after sonication with 1 MHz continuous ultrasound at the intensities of 0.61-2.44 W/cm2. Free radicals and hydrogen peroxide produced by ultrasound exposure of cells can lead to DNA damage. Comet assay was used to assess the effect of ultrasound on the level of nuclear DNA damage. The nucleated erythrocytes from fish were exposed in vitro to ultrasound at the same intensities and frequency. It was noticed that ultrasound in all used intensities induced DNA damage. The effect was not eliminated by the addition of catalase, which indicates that DNA damage was not caused by hydrogen peroxide only. The results showed that the DNA damage can be repair and this mechanism was the most effective after 30 and 60 min after sonication. Furthermore, the ultrasound-induced DNA damage in the presence of sonosensitizer (Zn- and AlCl-phthalocyanine) was studied. It was noticed that phthalocyaniens (Pcs) alone or with ultrasound did not induce significant changes in the level of DNA damage.

Variation of 1-pyrenebutyric acid fluorescence lifetime in single living cells treated with molecules increasing or decreasing reactive oxygen species levels

1-Pyrenebutyric acid (PBA) is a fluorescent probe whose fluorescence lifetime depends on local oxygen and free radical concentrations. We propose to use PBA fluorescence lifetime to quantify reactive oxygen species (ROS) in biological samples. Time-resolved microfluorimetry was used to record the fluorescence decay of single living cells loaded with this probe. We measured intracellular PBA fluorescence lifetimes and reduced nicotinamide adenine dinucleotide phosphate intensities under various oxygen concentrations. To confirm the feasibility of the new method, CCRF-CEM cells were treated with drugs that are known to increase or decrease ROS production. After treatment with adriamycin, we observed a decrease of PBA fluorescence lifetime. This corresponded to an increase of ROS concentration (80%). After treatment with cysteamine, we observed a reduction of the ROS concentration by 67%. Moreover, addition of exogenous H(2)O(2) solution resulted in a decrease of PBA fluorescence lifetime due to a raising of the intracellular ROS concentration. These results support our hypothesis linking a part of PBA fluorescence lifetime variations to intracellular fluctuation of ROS.

Sonodynamic therapy--a review of the synergistic effects of drugs and ultrasound

Sonodynamic therapy, the ultrasound dependent enhancement of cytotoxic activities of certain compounds (sonosensitizers) in studies with cells in vitro and in tumor bearing animals, is reviewed. The attractive features of this modality for cancer treatment emerges from the ability to focus the ultrasound energy on malignancy sites buried deep in tissues and to locally activate a preloaded sonosensitizer. Possible mechanisms of sonodynamic therapy include generation of sonosensitizer derived radicals which initiate chain peroxidation of membrane lipids via peroxyl and/or alkoxyl radicals, the physical destabilization of the cell membrane by the sonosensitizer thereby rendering the cell more susceptible to shear forces or ultrasound enhanced drug transport across the cell membrane (sonoporation). Evidence against the role of singlet oxygen in sonodynamic therapy is discussed. The mechanism of sonodynamic therapy is probably not governed by a universal mechanism, but may be influenced by multiple factors including the nature of the biological model, the sonosensitizer and the ultrasound parameters. The current review emphasizes the effect of ultrasound induced free radicals in sonodynamic therapy.

The effect of heterogeneous solvent systems on sonochemical reactions: accelerated degradation of alkyl thiols in emulsion

Sonochemical reactions of alkyl and aryl thiols in water-organic mixed solvent systems were kinetically investigated. The reaction in the liquid-liquid interface apparently depends on the polarities, surface activities, vapor pressures and hydrophobicities of organic solvents and thiols. Interestingly, the rate jump in sonochemical disappearance of alkyl thiols was observed under emulsified conditions.

Ultrasound-enhanced transgene expression in vascular cells is not dependent upon cavitation-induced free radicals

Although acoustic cavitation is clearly important in ultrasound (US)-enhanced gene delivery (UEGD), the relative importance of mechanical and sonochemical (free radical) bioeffects remains unclear, as does the mechanism of gene delivery at the cellular level. Porcine vascular smooth muscle cells (VSMC) were transfected with luciferase or green fluorescent protein (GFP) plasmid +/- pulsed 956 kHz US (2.0 mechanical index (MI), 128 W cm(-2) spatial peak pulse average intensity, ISPPA) for 60 s, in the presence or absence of 20 mM cysteamine or N-acetyl-L-cysteine. Both compounds effectively scavenged free radical production following US, leaving unaffected the 50- to 100-fold enhancements in luciferase expression seen in US-treated VSMC. US exposure enhanced plasmid uptake (25 +/- 4.6 vs. 3 +/- 1.9 cells/field, n=4, p<0.05), most likely directly into the cytoplasm, and increased both the total number (>sevenfold) and average fluorescence intensity (>sixfold) of GFP-transfected cells. UEGD is not dependent upon cavitation-induced free radical generation and has potential for use with a wide range of therapeutic transgenes.

Therapeutic effects of cystamine in a murine model of Huntington's disease

The precise cause of neuronal death in Huntington's disease (HD) is unknown. Proteolytic products of the huntingtin protein can contribute to toxic cellular aggregates that may be formed in part by tissue transglutaminase (Tgase). Tgase activity is increased in HD brain. Treatment in R6/2 transgenic HD mice, using the transglutaminase inhibitor cystamine, significantly extended survival, improved body weight and motor performance, and delayed the neuropathological sequela. Tgase activity and N(Sigma)-(gamma-L-glutamyl)-L-lysine (GGEL) levels were significantly altered in HD mice. Free GGEL, a specific biochemical marker of Tgase activity, was markedly elevated in the neocortex and caudate nucleus in HD patients. Both Tgase and GGEL immunoreactivities colocalized to huntingtin aggregates. Cystamine treatment normalized transglutaminase and GGEL levels in R6/2 mice. These findings are consistent with the hypothesis that transglutaminase activity may play a role in the pathogenesis of HD, and they identify cystamine as a potential therapeutic strategy for treating HD patients.

EPR analysis of radicals generated in ultrasound-assisted lipoplasty simulated environment

The generation of various radicals by application of continuous wave (CW) high-intensity ultrasound energy (HIUE) to an aqueous biologic medium containing spin traps, under conditions simulating ultrasound-assisted lipoplasty (UAL), was demonstrated by EPR spectroscopy. The addition of water- soluble antioxidants, ascorbic acid and glutathione to the wetting solution substantially reduces the levels of hydroxyl radicals in the sonicated medium. These findings provide direct evidence for the generation of cavitation in the simulated intercellular environment, corroborating previous data, and pointing out that generation of transient cavitation in clinical UAL and other therapeutic and surgical applications of ultrasound is possible. The findings indicate that the effect of transient cavitation in aqueous biologic media may be similar to the effects of ionizing radiation, and raise the question of the long-term biosafety of the use of CW HIUE in UAL. The introduction of biocompatible water-soluble antioxidants to the sonicated medium may be utilized to suppress accumulation of radicals and reduce their possible adverse effects.