Time-dependent intracellular trafficking of FITC-conjugated epigallocatechin-3-O-gallate in L-929 cells

Epigallocatechin gallate regulates the myeloid-specific transcription factor PU.1 in macrophages

Our previous research demonstrated that PU.1 regulates expression of the genes involved in inflammation in macrophages. Selective knockdown of PU.1 in macrophages ameliorated LPS-induced acute lung injury (ALI) in bone marrow chimera mice. Inhibitors that block the transcriptional activity of PU.1 in macrophages have the potential to mitigate the pathophysiology of LPS-induced ALI. However, complete inactivation of PU.1 gene disrupts normal myelopoiesis. Although the green tea polyphenol Epigallocatechin gallate (EGCG) has been shown to regulate inflammatory genes in various cell types, it is not known if EGCG alters the transcriptional activity of PU.1 protein. Using Schrodinger Glide docking, we have identified that EGCG binds with PU.1 protein, altering its DNA-binding and self-dimerization activity. In silico analysis shows that EGCG forms Hydrogen bonds with Glutamic Acid 209, Leucine 250 in DNA binding and Lysine 196, Tryptophan 193, and Leucine 182 in the self-dimerization domain of the PU.1 protein. Experimental validation using mouse bone marrow-derived macrophages (BMDM) confirmed that EGCG inhibits both DNA binding by PU.1 and self-dimerization. Importantly, EGCG had no impact on expression of the total PU.1 protein levels but significantly reduced expression of various inflammatory genes and generation of ROS. In summary, we report that EGCG acts as an inhibitor of the PU.1 transcription factor in macrophages.

EGCG-induced selective death of cancer cells through autophagy-dependent regulation of the p62-mediated antioxidant survival pathway

The effects of EGCG on the selective death of cancer cells by modulating antioxidant pathways through autophagy were explored in various normal and cancer cells. EGCG positively regulated the p62-KEAP1-NRF2-HO-1 pathway in normal cells, while negatively regulating it in cancer cells, leading to selective apoptotic death of cancer cells. In EGCG-treated MRC5 cells (EGCG-MRC5), autophagic flux was blocked, which was accompanied by the formation of p62-positive aggregates. However, EGCG-treated HeLa cells (EGCG-HeLa) showed incomplete autophagic flux and no aggregate formation. The levels of P-ULK1 S556 and S758 increased in EGCG-MRC5 through AMPK-mTOR cooperative interaction. In contrast, EGCG treatment in HeLa cells led to AMPK-induced mTOR inactivation, resulting in abrogation of P-ULK1 S556 and S758 levels. AMPK knockout in EGCG-HeLa restored positive regulation of the p62-mediated pathway, which was accompanied by increased P-mTOR S2448 and P-ULK1 S758 levels. Knockdown of 67LR in EGCG-HeLa abolished AMPK activity but did not restore the p62-mediated pathway. Surprisingly, both AMPK knockout and 67LR knockdown in EGCG-HeLa markedly increased cell viability, despite differential regulation of the antioxidant enzyme HO-1. In conclusion, EGCG induces the selective death of cancer cells through the modulation of at least two autophagy-dependent and independent regulatory pathways: negative regulation involves the mTOR-ULK1 (S556 and S758)-p62-KEAP1-NRF2-HO-1 axis via AMPK activation, whereas positive regulation occurs through the 67LR-AMPK axis.

N-2-Hydroxypropylmethacrylamide-Polycaprolactone Polymeric Micelles in Co-delivery of Proteasome Inhibitor and Polyphenol: Exploration of Synergism or Antagonism

Breast cancer leads to the highest mortality among women resulting in a major clinical burden. Multidrug therapy is more efficient in such patients compared to monodrug therapy. Simultaneous combinatorial or co-delivery garnered significant interest in the past years. Caffeic acid (CFA) (a natural polyphenol) has received growing attention because of its anticarcinogenic and antioxidant potential. Bortezomib (BTZ) is a proteasome inhibitor and may be explored for treating breast cancer. Despite its high anticancer activity, the low water solubility and chemical instability restrict its efficacy against solid tumors. In the present study, we designed and investigated a HP-PCL (N-2-hydroxypropylmethacrylamide-polycaprolactone) polymeric micellar (PMCs) system for the simultaneous delivery of BTZ and CFA in the treatment of breast cancer. The designed BTZ+CFA-HP-PCL PMCs were fabricated, optimized, and characterized for size, zeta potential, surface morphology, and in vitro drug release. Developed nanosized (174.6 ± 0.24 nm) PMCs showed enhanced cellular internalization and cell cytotoxicity in both MCF-7 and MDA-MB-231 cells. ROS (reactive oxygen species) levels were highest in BTZ-HP-PCL PMCs, while CFA-HP-PCL PMCs significantly (p < 0.001) scavenged the ROS generated in 2',7'-dichlorofluorescein diacetate (DCFH-DA) assay. The mitochondrial membrane potential (MMP) assay revealed intense and significant green fluorescence in both types of cancer cells when treated with BTZ-HP-PCL PMCs (p < 0.001) indicating apoptosis or cell death. The pharmacokinetic studies revealed that BTZ-HP-PCL PMCs and BTZ+CFA-HP-PCL PMCs exhibited the highest bioavailability, enhanced plasma half-life, decreased volume of distribution, and lower clearance rate than the pure combination of drugs. In the organ biodistribution studies, the combination of BTZ+CFA showed higher distribution in the spleen and the heart. Overall findings of in vitro studies surprisingly resulted in better therapeutic efficiency of BTZ-HP-PCL PMCs than BTZ+CFA-HP-PCL PMCs. However, the in vivo tumor growth inhibition study performed in tumor-induced mice concluded that the tumor growth was inhibited by both BTZ-HP-PCL PMCs and BTZ+CFA-HP-PCL PMCs (p < 0.0001) more efficiently than pure BTZ and the combination (BTZ+CFA), which may be due to the conversion of boronate ester into boronic acid. Henceforth, the combination of BTZ and CFA provides further indications to be explored in the future to support the hypothesis that BTZ may work with polyphenol (CFA) in the acidic environment of the tumor.

Size Dependency of Selective Cellular Uptake of Epigallocatechin Gallate-modified Gold Nanoparticles for Effective Radiosensitization

The high incidence and mortality of cancer make it a global health issue. However, conventional cancer therapies have several disadvantages, especially serious side effects due to low selective toxicity to cancer cells. Gold nanoparticles (AuNPs) are an excellent drug carrier, enhance drug delivery efficiency, and hold promise for photothermal and radiation therapies. (-)-Epigallocatechin-3-gallate (EGCG) is the major polyphenolic antioxidant constituent of green tea, has a potent antitumor effect, and binds specifically to the 67 kDa laminin receptor, which is overexpressed on the surface of several cancer cell lines such as HeLa and MDA-MB-231 cells. We synthesized EGCG-modified AuNPs (EGCG-AuNPs) using ratios (n_EGCG/n_gold) from 1:2 to 10:1 and evaluated their size, morphology, stability, antioxidant ability, cytotoxicity, cellular uptake, and uptake mechanisms in vitro in comparison with the conventional AuNPs prepared by using citrate as the reducing agent (citrate-AuNPs). In HeLa cells, EGCG-AuNPs (10:1) (135 nm diameter, sea-urchin-like shape) exhibited the highest cellular uptake. Conversely, EGCG-AuNPs (1:2) (39 nm diameter, spherical shape) were preferentially taken up by MDA-MB-231 cells. Cellular uptake of EGCG-AuNPs toward normal cells (NIH3T3 cells) was found to be in a nonspecific manner, and the amount of uptake was suppressed. X-ray irradiation after cellular uptake of EGCG-AuNPs (1:2) in MDA-MB-231 cells significantly enhanced irradiation-induced cell death. These findings suggest enhanced cellular uptake of EGCG-AuNPs with a 39 nm diameter and their potential use in combinatorial therapeutics of EGCG-AuNPs for breast cancer.

Effect of epigallocatechin-3-gallate on tumor necrosis factor-alpha production by human gingival fibroblasts stimulated with bacterial lipopolysaccharide: An in vitro study

Background:

Evidence shows that epigallocatechin-3-gallate (EGCG) in green tea has anti-inflammatory effects.

Aim:

This study assessed the effect of EGCG on the production of tumor necrosis factor-alpha (TNF-α) as an inflammatory cytokine in periodontitis, which produced by human gingival fibroblasts (HGFs) stimulated with lipopolysaccharide (LPS) of Porphyromonas gingivalis.

Materials and Methods:

In this study, HGFs were cultured and subjected to LPS and EGCG. Cell viability of different concentrations of EGCG (10, 25, 50, 75, and 100 μM) and LPS (1, 10, 20, and 50 μg/mL) was assessed using methyl-thiazole-tetrazolium (MTT) assay. Then, the best concentrations of EGCG and P. gingivalis LPS were used simultaneously and separately to assess the production of TNF-α by HGFs using the enzyme-linked immunosorbent assay (ELISA). Assessments were done at 1, 3, and 5 days. Data were read using the ELISA reader and analyzed by the SPSS through two-way ANOVA.

Results:

LPS at 1, 10, and 20 and EGCG at 10.25 and 50 μM showed the least cytotoxicity in MTT assay. ELISA showed EGCG alone decreased the production of TNF-α in all days, except 10 μM on day 1. 1, 10, and 20 μg/mL LPS increased the output of TNF-α on days 1 and 3 while reducing it on day 5. The combination of EGCG and LPS showed a decrease of TNF-α in all days except on day 5 that revealed an increase in the production of TNF-α at 25 and 50 μM EGCG.

Conclusion:

In the combination use of EGCG and LPS, EGCG shows anti-inflammatory effects by decreasing the production of TNF-α by HGFs stimulated with P. gingivalis.

Synthesis of a Removable Cytoprotective Exoskeleton by Tea Polyphenol Complexes for Living Cell Encapsulation

Cell encapsulation is a chemical tool for endowing living cells with exogenous properties and enhancing their in vitro tolerance against lethal factors, which has shown promising prospects and potential applications in many fields such as cell transplantation, drug delivery, and tissue engineering. One-pot precipitation of a polyphenol-metal complex on cells protects cells from UV irradiation and lytic enzymes. However, the involvement of metal ions brings side effects on cell viability and growth. Moreover, an external removal agent is needed for cell division and growth. Herein, a polymer shell composed of hydrogen bonded constituents without affecting cell viability and growth by the precipitation of tea polyphenol and polyvinyl pyrrolidone is reported. The formation of the polymer shell was verified by the Au nanoparticle's laser scanning confocal reflectance and quartz crystal microbalance measurement. The thickness of the shell was managed by the concentration of the complex. When exposed to UV irradiation for 15 or 30 min, polymer-coating-protected Saccharomyces cerevisiae (yeast) had much higher cell viability than the native one. Exposed to a high temperature environment (60 °C), most of the coated yeasts survived in contrast to uncoated ones. For the cell division and growth curve, the polymer coating with various thicknesses had no difference to the native one, which indicated no suppression of cell growth and no external side effects involved. As applied to mammalian HeLa cells under UV irradiation for 15 min, the coated cells had an obvious higher cell viability than that of untreated ones. Therefore, the tea polyphenol-poly(vinylpyrrolidone) shell is a versatile tool for chemically controlling the external properties of cells without side effects on cell viability and growth.

N-doped carbon dots modified with the epithelial cell adhesion molecule antibody as an imaging agent for HepG2 cells using their ultra-sensitive response to Al3

Carbon dots (CDs) are emerging as an ideal multifunctional materials due to their ease of preparation and excellent properties in medical imaging technology, environmental monitoring, chemical analysis and other fields. N-doped CDs modified with the epithelial cell adhesion molecule antibody (anti-EpCAM-NCDs) were synthesized in an ingenious and high-output approach. Due to the fluorescence enhancement effect of the introduced N atoms, the obtained anti-EpCAM-NCDs exhibited a strong green emission with an absolute quantum yield of up to 32.5%. Anti-EpCAM-NCDs have immunofluorescent properties and an active targeting function. The fluorescence effect and fluorescence quenching of anti-EpCAM-NCDs are used to image cells and detect Al³⁺, respectively. Experimental results show that this probe exhibited a wide linear response to Al³⁺over a concentration range of 0-100μM with a detection limit and quantification limit of 3 nM and 6 nM, respectively. Significantly, anti-EpCAM-NCDs, which have negligible cytotoxicity, excellent biocompatibility and high photostability, could be used for the intracellular imaging of HepG2 cells and the detection of Al³⁺in environmental and biological samples. As an efficient multifunctional material, anti-EpCAM-NCDs hold great promise for a number of applications in biological systems.

Targeted Pulmonary Delivery of the Green Tea Polyphenol Epigallocatechin Gallate Controls the Growth of Mycobacterium tuberculosis by Enhancing the Autophagy and Suppressing Bacterial Burden

Growing rates of tuberculosis (TB) superbugs are alarming, which has hampered the progress made to-date to control this infectious disease, and new drug candidates are few. Epigallocatechin gallate (EGCG), a major polyphenolic compound from green tea extract, shows powerful efficacy against TB bacteria in in vitro studies. However, the therapeutic efficacy of the molecule is limited due to poor pharmacokinetics and low bioavailability following oral administration. Aiming to improve the treatment outcomes of EGCG therapy, we investigated whether encapsulation and pulmonary delivery of the molecule would allow the direct targeting of the site of infection without compromising the activity. Microencapsulation of EGCG was realized by scalable spray-freeze-drying (SFD) technology, forming free-flowing micrometer-sized microspheres (epigallocatechin-3-gallate-loaded trehalose microspheres, EGCG-t-MS) of trehalose sugar. These porous microspheres exhibited appropriate aerodynamic parameters and high encapsulation efficiencies. In vitro studies demonstrated that EGCG-t-MS exhibited dose- and time-dependent killing of TB bacteria inside mouse macrophages by cellular mechanisms of lysosome acidification and autophagy induction. In a preclinical study on TB-infected Balb/c mice model (4 weeks of infection), we demonstrate that the microencapsulated EGCG, administered 5 days/week for 6 weeks by pulmonary delivery, showed exceptional efficacy compared to oral treatment of free drug. This treatment approach exhibited therapeutic outcomes by resolution of inflammation in the infected lungs and significant reduction (P < 0.05) in bacterial burden (up to ∼2.54 Log₁₀ CFU) compared to untreated control and orally treated mice groups. No pathological granulomas, lesions, and inflammation were observed in the histopathological investigation, compared to untreated controls. The encouraging results of the study may pave the avenues for future use of EGCG in TB therapeutics by targeted pulmonary delivery and lead to its translational success.

Carbon dots with red emission for bioimaging of fungal cells and detecting Hg2+ and ziram in aqueous solution

It is of importance for bioimaging of fungal cells using biocompatible and low toxic carbon dots (CDs) as labels in plant protection field because a clearer understanding on the infection mechanism of fungi on plant can be achieved. Meanwhile, long wavelength, especially, red/near-infrared (NIR) emissive CDs are more biocompatible than short wavelength emissive ones. In this work, CDs with red emission were synthesized by solvothermal pyrolysis of citric acid, acrylamide dissolved in formamide. Fungal cells stained by the CDs with red emission were brightly illuminated when imaged on a fluorescent microscope with excitation by a green laser pulse, suggesting the CDs are of an excellent label for bioimaging of fungal cell in red color region. Moreover, the CDs show a selective response to Hg²⁺ in the NaAc-HAc buffer solution, while ziram can form a more stable complex with Hg²⁺, leading to a recovery of the quenched fluorescence of the CDs. Therefore, methods for the detections of Hg²⁺ and ziram based on the "off-on" fluorescence of the CDs were established with limits of detection as low as 0.19 μM and 0.55 μg/mL.

Nitrogen-doped carbon dots as fluorescence ON-OFF-ON sensor for parallel detection of copper(ii) and mercury(ii) ions in solutions as well as in filter paper-based microfluidic device

Due to improper garbage disposal and rapid industrialization, concentrations of different metal ions are rising to toxic levels in natural water sources. Development of novel, selective and sensitive sensors for different metal ions is in high demand for rapid detection and remediation. Herein, we report nitrogen-doped carbon dots (NCDs) with high blue fluorescence, synthesized by a new one-step pyrolytic method using urea and ethylenediaminetetraacetic (EDTA) acid as precursors. The NCDs were used for parallel detection of Hg²⁺ and Cu²⁺ ions in aqueous medium through a fluorescence ON-OFF-ON process. The minimum detection limit for Hg²⁺ and Cu²⁺ were 6.2 nM and 2.304 nM, respectively, in aqueous medium, which is close to or below the allowed levels of Hg²⁺ and Cu²⁺ ions, i.e., 6 ppb and 2 ppm, respectively, in drinking water as per World Health Organisation (WHO). Hg²⁺ and Cu²⁺ ions were discriminated with vitamin C (ascorbic acid) and trisodium citrate by a fluorescence turn on process. A filter paper based microfluidic device loaded with NCDs, vitamin C and trisodium citrate was developed using candle wax channels on a filter paper as a proof of principle, projecting NCDs as a promising material for parallel detection of multiple metal ions. The device demonstrated herein is capable of detecting Hg²⁺ and Cu²⁺ ions up to 0.1 μM. This simple, low cost, disposable paper-based device will be very useful for rapid onsite analysis.

Protective Effects of Epigallocatechin-3-Gallate from Green Tea in Various Kidney Diseases

Kidney diseases are common health problems worldwide. Various etiologies (e.g., diabetes, hypertension, drug-induced nephrotoxicity, infection, cancers) can affect renal function and ultimately lead to development of chronic kidney disease (CKD) and end-stage renal disease (ESRD). The global rise in number of CKD/ESRD patients during recent years has led to tremendous concern to look for effective strategies to prevent or slow progression of CKD and ESRD. Natural compounds derived from herbs or medicinal plants have gained wide attention for scientific scrutiny to achieve such goals. One of such natural compounds that has been extensively investigated is epigallocatechin-3-gallate (EGCG), a major polyphenol found in the tea plant (Camellia sinensis). A growing body of recent evidence has shown that EGCG may be a promising therapeutic or protective agent in various kidney diseases. This article thus highlights recent progress in medical research on beneficial effects of EGCG against a broad spectrum of kidney diseases, including acute kidney injury, cisplatin-induced nephrotoxicity, kidney stone disease, glomerulonephritis, lupus nephritis, renal cell carcinoma, diabetic nephropathy, CKD, and renal fibrosis. The renoprotective mechanisms are also detailed. Finally, future perspectives of medical research on EGCG and its potential use in clinical practice for treatment and prevention of kidney diseases are discussed.

Perspectives on the recent developments with green tea polyphenols in drug discovery

INTRODUCTION

Increasing evidence has expanded the role of green tea from a traditional beverage to a source of pharmacologically active molecules with diverse health benefits. However, conclusive clinical results are needed to better elucidate the cancer-preventive and therapeutic effects of green tea polyphenols (GTPs). Areas covered: The authors describe GTPs' chemical compositions and metabolic biotransformations, and their recent developments in drug discovery, focusing on their cancer chemopreventive and therapeutic effects. They then review the recent development of GTP-loaded nanoparticles and GTP prodrugs. Expert opinion: GTPs possess potent anticarcinogenic activities through interfering with the initiation, development and progression phases of cancer. There are several challenges (e.g. poor bioavailability) in developing GTPs as therapeutic agents. Use of nanoparticle-based delivery systems has provided unique advantages over purified GTPs. However, there is still a need to determine the actual magnitude and pharmacological mechanisms of GTPs encapsulated in nanoparticles, in order to address newly emerging safety issues associated with the potential 'local overdose' effect. The use of Pro- epigallocatechin gallate (Pro-EGCG) as a prodrug appears to offer improved in vitro stability as well as better in vivo bioavailability and efficacies in a number of animal studies, suggesting its potential as a therapeutic agent for further study and development.

Effects of polyphenols on doxorubicin-induced oral keratinocyte cytotoxicity and anticancer potency against oral cancer cells

BACKGROUND

Normal human oral keratinocytes are highly sensitive to anticancer drugs including doxorubicin. Resveratrol, epigallocatechin gallate, and tannic acid are polyphenolic compounds that were reported to have cardioprotective effect when combined with doxorubicin. However, it is unknown whether these polyphenols could protect normal human oral keratinocytes against doxorubicin-induced cytotoxicity without weakening its cytotoxic potential against oral cancer cells. Here, we examined the effects of the 3 polyphenolic compounds on doxorubicin-induced cytotoxicity in normal human oral keratinocytes and also investigated their effects on doxorubicin potency in HSC-2 human oral squamous cell carcinoma cells.

METHODS

Cell viability was evaluated, followed by the analysis of apoptosis and necrosis. The changes in intracellular reactive oxygen species at the early stage after treatment were also examined.

RESULTS

The results revealed that resveratrol in combination with doxorubicin additively augmented doxorubicin cytotoxicity in both types of cells. However, epigallocatechin gallate and tannic acid at a certain concentration mitigated the doxorubicin-induced keratinocyte toxicity mainly due to reduced doxorubicin-induced necrosis in normal human oral keratinocytes without weaken doxorubicin anticancer efficacy. The exact mechanism is still unknown but intracellular reactive oxygen species might be not the sole factor.

CONCLUSIONS

This study for the first time reported the effects of resveratrol, epigallocatechin gallate, and tannic acid on doxorubicin-induced cytotoxicity in normal oral keratinocytes and oral cancer cells. The combined use of epigallocatechin gallate or tannic acid with doxorubicin at a certain concentration could mitigate doxorubicin-induced keratinocyte cytotoxicity without weakening doxorubicin anticancer efficacy.

Derivatives of alkyl gallate triphenylphosphonium exhibit antitumor activity in a syngeneic murine model of mammary adenocarcinoma

We previously demonstrated that alkyl gallates coupled to triphenylphosphine have a selective and efficient antiproliferative effect by inducing mitochondrial uncoupling in vitro due to the increased mitochondrial transmembrane potential of tumor cells. Therefore, in this work, the in vivo antitumor activities of alkyl gallate triphenylphosphonium derivatives (TPP+C8, TPP+C10 and TPP+C12) were evaluated in a syngeneic murine model of breast cancer. We found that TPP+C10 increased the cytosolic ADP/ATP ratio and significantly increased the AMP levels in a concentration-dependent manner in TA3/Ha murine mammary adenocarcinoma cells. Interestingly, TPP+C10 induced a decrease in the levels of cellular proliferation markers and promoted caspase-3 activation in tumor-bearing mice. Additionally, TPP+C10 inhibited tumor growth in the syngeneic mouse model. Importantly, 30days of intraperitoneal (i.p.) administration of the combination of TPP+C10 (10mg/kg/48h) and the antibiotic doxycycline (10mg/kg/24h) completely eliminated the subcutaneous tumor burden in mice (n=6), without any relapses at 60days post-treatment. This enhancement of the individual activities of TPP+C10 and doxycycline is due to the uncoupling of oxidative phosphorylation by TPP+C10 and the inhibition of mitochondrial biogenesis by doxycycline, as demonstrated by loss of mitochondrial mass and overexpression of PGC1-α as an adaptive response. Moreover, i.p. administration of TPP+C10 (10mg/kg/24h) to healthy mice did not produce toxicity or damage in organs important for drug metabolism and excretion, as indicated by hematological, biochemical and histological assessments. These findings suggest that the combination of TPP+C10 with doxycycline is a valuable candidate therapy for breast cancer management.

Theaflavins from black tea affect growth, development, and motility in Dictyostelium discoideum

Theaflavins, flavonoids found in black tea, exhibit a variety of health-promoting activities, but the mechanisms by which they act are not clear. Here, we assess the effects of black tea extract and isolated theaflavins on Dictyostelium discoideum, a model organism exhibiting an unusual life cycle relying on conserved pathways involved in human disease. Dictyostelium has been used to characterize the activities of numerous bioactive small molecules, including catechins, from which theaflavins are produced during the preparation of black tea. We show that theaflavins block growth, development, and motility in Dictyostelium, results that suggest catechins and theaflavins exert similar activities in this organism.

Cancer Chemoprevention by Phytochemicals: Nature's Healing Touch

Phytochemicals are an important part of traditional medicine and have been investigated in detail for possible inclusion in modern medicine as well. These compounds often serve as the backbone for the synthesis of novel therapeutic agents. For many years, phytochemicals have demonstrated encouraging activity against various human cancer models in pre-clinical assays. Here, we discuss select phytochemicals—curcumin, epigallocatechin-3-gallate (EGCG), resveratrol, plumbagin and honokiol—in the context of their reported effects on the processes of inflammation and oxidative stress, which play a key role in tumorigenesis. We also discuss the emerging evidence on modulation of tumor microenvironment by these phytochemicals which can possibly define their cancer-specific action. Finally, we provide recent updates on how low bioavailability, a major concern with phytochemicals, is being circumvented and the general efficacy being improved, by synthesis of novel chemical analogs and nanoformulations.

Rational designed strategy to dispel mutual interference of mercuric and ferric ions towards robust, pH-stable fluorescent carbon nanodots

C-dots based stable and recoverable sensing platform with switchable selectivity for Hg²⁺ and Fe³⁺ was rationally designed.

The role of natural polyphenols in cell signaling and cytoprotection against cancer development

The cytoprotective and anticancer action of dietary in-taken natural polyphenols has for long been attributed only to their direct radical scavenging activities. Currently it is well supported that those compounds display a broad spectrum of biological and pharmacological outcomes mediated by their complex metabolism, interaction with gut microbiota as well as direct interactions of their metabolites with key cellular signaling proteins. The beneficial effects of natural polyphenols and their synthetic derivatives are extensively studied in context of cancer prophylaxis and therapy. Herein we focus on cell signaling to explain the beneficial role of polyphenols at the three stages of cancer development: we review the recent proceedings about the impact of polyphenols on the cytoprotective antioxidant response and their proapoptotic action at the premalignant stage, and finally we present data showing how phenolic acids (e.g., caffeic, chlorogenic acids) and flavonols (e.g., quercetin) hamper the development of metastatic cancer.

Novel insights of dietary polyphenols and obesity

The prevalence of obesity has steadily increased over the past three decades both in the United States and worldwide. Recent studies have shown the role of dietary polyphenols in the prevention of obesity and obesity-related chronic diseases. Here, we evaluated the impact of commonly consumed polyphenols, including green tea catechins, especially epigallocatechin gallates, resveratrol and curcumin, on obesity and obesity-related inflammation. Cellular studies demonstrated that these dietary polyphenols reduce viability of adipocytes and proliferation of preadipocytes, suppress adipocyte differentiation and triglyceride accumulation, stimulate lipolysis and fatty acid β-oxidation, and reduce inflammation. Concomitantly, the polyphenols modulate signaling pathways including the adenosine-monophosphate-activated protein kinase, peroxisome proliferator activated receptor γ, CCAAT/enhancer binding protein α, peroxisome proliferator activator receptor gamma activator 1-alpha, sirtuin 1, sterol regulatory element binding protein-1c, uncoupling proteins 1 and 2, and nuclear factor-κB that regulate adipogenesis, antioxidant and anti-inflammatory responses. Animal studies strongly suggest that commonly consumed polyphenols described in this review have a pronounced effect on obesity as shown by lower body weight, fat mass and triglycerides through enhancing energy expenditure and fat utilization, and modulating glucose hemostasis. Limited human studies have been conducted in this area and are inconsistent about the antiobesity impact of dietary polyphenols probably due to the various study designs and lengths, variation among subjects (age, gender, ethnicity), chemical forms of the dietary polyphenols used and confounding factors such as other weight-reducing agents. Future randomized controlled trials are warranted to reconcile the discrepancies between preclinical efficacies and inconclusive clinic outcomes of these polyphenols.

Enhanced uptake and transport of (+)-catechin and (-)-epigallocatechin gallate in niosomal formulation by human intestinal Caco-2 cells

The aim of this study was to evaluate (+)-catechin and (−)-epigallocatechin gallate (EGCG) cellular uptake and transport across human intestinal Caco-2 cell monolayer in both the absence and presence of niosomal carrier in variable conditions. The effect of free drugs and drug-loaded niosomes on the growth of Caco-2 cells was studied. The effects of time, temperature, and concentration on drug cellular uptake in the absence or presence of its niosomal delivery systems were investigated. The intestinal epithelial membrane transport of the drug-loaded niosomes was examined using the monolayer of the human Caco-2 cells. The kinetics of transport, and the effect of temperature, adenosine triphosphate inhibitor, permeability glycoprotein inhibitor, multidrug resistance-associated protein 2 inhibitor, and the absorption enhancer on transport mechanism were investigated. It was found that the uptake of catechin, EGCG, and their niosomes by Caco-2 cells was 1.22±0.16, 0.90±0.14, 3.25±0.37, and 1.92±0.22 μg/mg protein, respectively (n=3). The apparent permeability coefficient values of catechin, EGCG, and their niosomes were 1.68±0.16, 0.88±0.09, 2.39±0.31, and 1.42±0.24 cm/second (n=3) at 37°C, respectively. The transport was temperature- and energy-dependent. The inhibitors of permeability glycoprotein and multidrug resistance-associated protein 2 and the absorption enhancer significantly enhanced the uptake amount. Compared with the free drugs, niosomal formulation significantly enhanced drug absorption. Additionally, drug-loaded niosomes exhibited stronger stability and lower toxicity. These findings showed that the oral absorption of tea flavonoids could be improved by using the novel drug delivery systems.

Induction of the connexin 32 gene by epigallocatechin-3-gallate potentiates vinblastine-induced cytotoxicity in human renal carcinoma cells

BACKGROUND/AIM

Enforced expression of the connexin (Cx) 32 gene, a member of the gap junction gene family and a tumor suppressor gene in human renal cell carcinoma (RCC), enhanced vinblastine (VBL)-induced cytotoxicity in RCC cells due to suppression of multidrug resistance 1 (MDR1) expression. Furthermore, in RCC the Cx32 gene is silenced by hypermethylation of CpG islands in a promoter region of the Cx gene. In this study, we investigated if the green tea polyphenol epigallocatechin-3-gallate (EGCG) could enhance susceptibility of RCC cells (Caki-1, a human metastatic RCC cell) to VBL.

METHODS

The effects of EGCG on Caki-1 cells were estimated by WST-1 (cell viability), real-time RT-PCR (mRNA level) and immunoblotting (protein level). We estimated the methylation status in the promoter region of the Cx32 gene in RCC cells by methylation-specific PCR. Each protein function was inhibited by small interfering RNA (siRNA) and specific inhibitors.

RESULTS

The EGCG treatment elicited significant upregulation of Cx32 in Caki-1 cells, and the induction of the Cx led to the suppression of MDR1 mRNA expression through inactivation of Src and subsequent activation of c-Jun NH2-terminal kinase (JNK). Chemical sensitivity to VBL in Caki-1 cells was increased by EGCG pretreatment, and this effect was abrogated by siRNA-mediated knockdown of Cx32.

CONCLUSION

This study suggests that the restoration of Cx32 by EGCG pretreatment improves chemical tolerance on VBL in Caki-1 cells via the inactivation of Src and the activation of JNK.

Cellular targets for the beneficial actions of tea polyphenols

Green and black teas contain different biologically active polyphenolic compounds that might offer protection against a variety of human diseases. Although promising experimental and clinical data have shown protective effects, limited information is available on how these beneficial effects of tea polyphenols are mediated at the cellular level. Evidence is accumulating that catechins in green tea as well as theaflavins and thearubigins from black tea are the substances responsible for the physiologic effects of tea in vitro. The green tea catechin epigallocatechin-3-gallate (EGCG) is generally considered to be the biologically most active compound in vitro. The changes in the activities of various protein kinases, growth factors, and transcription factors represent a common mechanism involved in cellular effects of tea polyphenols. In addition to modification of intracellular signaling by activation of cellular receptors, it was shown that, at least for EGCG, tea polyphenols can enter the cells and directly interact with their molecular targets within cells. There, they frequently result in opposite effects in primary compared with tumor cells. Although tea polyphenols were long regarded as antioxidants, research in recent years has uncovered their prooxidant properties. The use of high nonphysiologic concentrations in many cell culture studies raises questions about the biological relevance of the observed effects for the in vivo situation. Efforts to attribute functional effects in vivo to specific molecular targets at the cellular level are still ongoing.

Cell imaging and DNA delivery in fibroblastic cells by conjugated polyelectrolytes

This study concentrates on the potential application of conjugated polyelectrolytes (CPEs) to cell imaging and DNA delivery. Four different types of polyfluorene copolymers, namely, PAHFP-Br, PAEFP-Br, PAHFbT-Br, and PSBFP-Na, which have the same π-conjugated backbone but different side chains, were synthesized. For cytotoxicity testing, L-929 fibroblastic cells were treated with increasing concentrations (0-50 µM) of each CPE and then cell viability was determined by WST-8 assay. Cellular uptake of CPEs into cultured L-929 cells was observed by fluorescence microscopy. To examine DNA delivery by CPEs, the cells were incubated for 1 H with PAHFP-Br/fluorescein (Fl)-labeled single-stranded DNA (ssDNA-Fl) complex and then visualized by fluorescence microscopy. Cytotoxicity of CPEs was increased in a dose-dependent manner but at lower than 10 µM, PAHFP-Br, PAEFP-Br, and PSBFP-Na did not show any cytotoxic effects on the cells. When added to cell cultures at 1 µM, PAHFP-Br/ssDNA-Fl complex was delivered and then dissociated into PAHFP-Br and ssDNA-Fl within the cells. This result implies that PAHFP-Br can enable cell imaging and DNA delivery into fibroblastic cells. Therefore, it is suggested that PAHFP-Br with various advantages such as low cytotoxicity and high fluorescence efficiency can be extensively used as a potential agent for cell imaging and gene delivery.

c(RGDfK) decorated micellar drug delivery system for intravesical instilled chemotherapy of superficial bladder cancer

The aim of this work was to develop a targeted drug delivery system with potentials for intravesical instilled chemotherapy of superficial bladder cancer. The amphiphilic diblock copolymer poly(ε-caprolactone)-b-poly(ethylene oxide) (PCL-b-PEO) was first conjugated with the cyclic (Arginine-Glycine-Aspartic acid-d-Phenylalanine-Lysine) (c(RGDfK)) and fluorescein isothiocyannate (FITC) via the functional terminal groups of hydrophilic block, and then assembled into micelles. The interaction between micelles and various model cells was well studied by means of confocal laser scanning microscopy and flow cytometry. The c(RGDfK) on the surface of the micelle was confirmed by (1)H NMR analysis and cell affinity with human glioblastoma-astrocytoma cells (U87MG). The cell viability of bladder cancer cells (T-24 cells) after incubation with doxorubicin (DOX) loaded polymeric micelles was evaluated by in vitro cytotoxicity assay. The results revealed that c(RGDfK) modified micelles showed strong affinity to T-24 cells and strong inhibitory effect on the proliferation of T-24 cells when doxorubicin drug was loaded, indicating the high affinity of c(RGDfK) to bladder cancer cells. The c(RGDfK) modified micelles assembled from PCL-b-PEO diblock copolymers developed in this study are of great potentials as nano-scaled drug delivery system for intravesical instilled chemotherapy of superficial bladder cancer.

Design Strategies for Fluorescent Biodegradable Polymeric Biomaterials

The marriage of biodegradable polymer and fluorescent imaging has resulted in an important area of polymeric biomaterials: biodegradable fluorescent polymers. Researchers have put significant efforts on developing versatile fluorescent biomaterials due to their promising in biological/biomedical labeling, tracking, monitoring, imaging, and diagnostic applications, especially in drug delivery, tissue engineering, and cancer imaging applications. Biodegradable fluorescent polymers can function not only as implant biomaterials but also as imaging probes. Currently, there are two major classes of biodegradable polymers used as fluorescent materials. The first class is the combination of non-fluorescent biodegradable polymers and fluorescent agents such as organic dyes and quantum dots. Another class of polymers shows intrinsic photoluminescence as polymers by themselves carrying integral fluorescent chemical structures in or pendent to their polymer backbone, such as Green Fluorescent protein (GFP), and the recently developed biodegradable photoluminescent polymer (BPLP). Thus there is no need to conjugate or encapsulate additional fluorescent materials for the latter. In the present review, we will review the fluorescent biodegradable polymers with emphases on material fluorescence mechanism, design criteria for fluorescence, and their cutting-edge applications in biomedical engineering. We expect that this review will provide insightful discussion on the fluorescent biomaterial design and lead to innovations for the development of the next generation of fluorescent biomaterials and fluorescence-based biomedical technology.

Anti-inflammatory effect of (-)-epigallocatechin-3-gallate on Porphyromonas gingivalis lipopolysaccharide-stimulated fibroblasts and stem cells derived from human periodontal ligament

PURPOSE

(-)-epigallocatechin-3-gallate (EGCG) has been reported to exert anti-inflammatory and antibacterial effects in periodontitis. However, its exact mechanism of action has yet to be determined. The present in vitro study evaluated the anti-inflammatory effects of EGCG on human periodontal ligament fibroblasts (hPDLFs) and human periodontal ligament stem cells (hPDLSCs) affected by bacterial lipopolysaccharide (LPS) extracted from Porphyromonas gingivalis.

METHODS

hPDLFs and hPDLSCs were extracted from healthy young adults and were treated with EGCG and/or P. gingivalis LPS. After 1, 3, 5, and 7 days from treatment, cytotoxic and proliferative effects were evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and bromodeoxyuridine assay, respectively. And then, the gene expressions of hPDLFs and hPDLSCs were observed for interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, osteoprotegerin (OPG), receptor activator of nuclear factor kappa-B ligand (RANKL), and RANKL/OPG using real-time polymerase chain reaction (PCR) at 0, 6, 24, and 48 hours after treatment. The experiments were performed with the following groups for hPDLFs and hPDLSCs; 1) No treat, 2) EGCG alone, 3) P. gingivalis LPS alone, 4) EGCG+P. gingivalis LPS.

RESULTS

The 20 µM of EGCG and 20 µg/mL of P. gingivalis LPS had the lowest cytotoxic effects, so those concentrations were used for further experiments. The proliferations of hPDLFs and hPDLSCs increased in all groups, though the 'EGCG alone' showed less increase. In real-time PCR, the hPDLFs and hPDLSCs of 'EGCG alone' showed similar gene expressions to those cells of 'no treat'. The gene expressions of 'P. gingivalis LPS alone' in both hPDLFs and hPDLSCs were highly increased at 6 hours for IL-1β, IL-6, TNF-α, RANKL, and RANKL/OPG, except the RANKL/OPG in hPDLSCs. However, those increased gene expressions were down-regulated in 'EGCG+P. gingivalis LPS' by the additional treatment of EGCG.

CONCLUSIONS

Our results demonstrate that EGCG could exert an anti-inflammatory effect in hPDLFs and hPDLSCs against a major pathogen of periodontitis, P. gingivalis LPS.

Preventive effects of epigallocatechin-3-O-gallate against replicative senescence associated with p53 acetylation in human dermal fibroblasts

Considering the various pharmacological activities of epigallocatechin-3-O-gallate (EGCG) including anticancer, and anti-inflammatory, antidiabetic, and so forth, relatively less attention has been paid to the antiaging effect of EGCG on primary cells. In this study, the preventive effects of EGCG against serial passage-induced senescence were investigated in primary cells including rat vascular smooth muscle cells (RVSMCs), human dermal fibroblasts (HDFs), and human articular chondrocytes (HACs). The involvement of Sirt1 and acetylated p53 was examined as an underlying mechanism for the senescence preventive activity of EGCG in HDFs. All cells were employed with the initial passage number (PN) between 3 and 7. For inducing senescence, the cells were serially passaged at the predetermined times and intervals in the absence or presence of EGCG (50 or 100 μM). Serial passage-induced senescence in RVSMCs and HACs was able to be significantly prevented at 50 μM EGCG, while in HDFs, 100 μM EGCG could significantly prevent senescence and recover their cell cycle progression close to the normal level. Furthermore, EGCG was found to prevent serial passage- and H(2)O(2)-induced senescence in HDFs by suppressing p53 acetylation, but the Sirt1 activity was unaffected. In addition, proliferating HDFs showed similar cellular uptake of FITC-conjugated EGCG into the cytoplasm with their senescent counterparts but different nuclear translocation of it from them, which would partly account for the differential responses to EGCG in proliferating versus senescent cells. Taking these results into consideration, it is suggested that EGCG may be exploited to craft strategies for the development of an antiaging or age-delaying agent.

Anti-angiogenic activity and intracellular distribution of epigallocatechin-3-gallate analogs

Angiogenesis, a process of construction of new blood capillaries, is crucial for tumor progression and metastasis. Our previous studies demonstrated that a component of green tea, epigallocatechin-3-gallate (EGCG), suppressed angiogenesis and subsequent tumor growth. In this study, to elucidate the detailed mechanism of the anti-angiogenic effect of EGCG and to enhance the antiangiogenic activity of EGCG, we designed and synthesized EGCG derivatives and examined their biological effect and intracellular localization in human umbilical vein endothelial cells (HUVECs). EGCG derivatives aminopentyl dideoxyEGCG and aminopentyl dideoxygallocatechin-3-gallate (cis-APDOEGCG and trans-APDOEGCG) had an enhanced inhibitory effect on the proliferation when used at more than 30 µM. To elucidate antiangiogenic effect of EGCG, we used a 1 µM concentration for subsequent experiments where no effect on proliferation was observed. These EGCG derivatives showed a stronger inhibitory effect on migration, invasion, and tube formation by HUVECs than the non-derivatized EGCG. Furthermore, the derivatives induced a change in the distribution of F-actin and subsequent morphology of the HUVECs. Next, we synthesized fluorescent TokyoGreen-conjugated EGCG derivative (EGCG-TG) and observed the distribution in HUVECs under a confocal laser scanning microscope. Abundant fluorescence was observed in the cells after a 3-h incubation, and was localized in mitochondria as well as in cytoplasm. These results suggest that EGCG was incorporated into the HUVECs, that a portion of it entered into their mitochondria.

Apoptosis of human fibrosarcoma HT-1080 cells by epigallocatechin-3-O-gallate via induction of p53 and caspases as well as suppression of Bcl-2 and phosphorylated nuclear factor-κB

Animal tumor bioassays and in vitro cell culture systems have demonstrated that epigallocatechin-3-O-gallate (EGCG), the predominant catechin in green tea, possesses anti-proliferative and pro-apoptotic effects on various cancer cells and tumors. In this study, we investigated the effects of EGCG on cell growth, cell cycle progression, and apoptosis in human fibrosarcoma HT-1080 cells. The involvement of p53, Bcl-2, Bax, caspases, and nuclear factor-κB (NF-κB) was examined as a mechanism for the anti-cancer activity of EGCG. Time-dependent intracellular trafficking of EGCG was also determined using fluorescein isothiocyanate (FITC)-conjugated EGCG (FITC-EGCG). Our data show that EGCG treatment caused dose-dependent cell growth inhibition, cell cycle arrest at the G(0)/G(1) phase, and DNA fragmentation suggesting the induction of apoptosis in HT-1080 cells. Immunoblot analysis revealed that the expression of p53, caspase-7 and -9 as well as the ratio of Bax/Bcl-2 protein increased significantly with higher EGCG concentrations and longer incubation times. Moreover, expression of phosphorylated NF-κB/p65 in HT-1080 cells was inhibited by EGCG treatment in a dose-dependent manner, while that of unphosphorylated NF-κB/p65 remained unaffected. Here we also reveal time-dependent internalization of FITC-EGCG into the cytosol of HT-1080 cells and its subsequent nuclear translocation. These results suggest that EGCG may interrupt exogenous signals directed towards genes involved in proliferation and cell cycle progression. Taken together, our data indicate that HT-1080 apoptosis may be mediated through the induction of p53 and caspases by the pro-oxidant activity of internalized EGCG, as well as suppression of Bcl-2 and phosphorylated NF-κB by the antioxidant activity of EGCG.

Epigallocatechin-3-gallate regulates cell growth, cell cycle and phosphorylated nuclear factor-κB in human dermal fibroblasts

AIM

To investigate the effects of (-)epigallocatechin-3-gallate (EGCG), the main polyphenol in green tea, on cell growth, cell cycle and phosphorylated nuclear factor-κB (pNF-κB) expression in neonatal human dermal fibroblasts (nHDFs).

METHODS

The proliferation and cell-cycle of nHDFs were determined using WST-8 cell growth assay and flow cytometry, respectively. The apoptosis was examined using DNA ladder and Annexin V-FITC assays. The expression levels of pNF-κB and cell cycle-related genes and proteins in nHDFs were measured using cDNA microarray analyses and Western blot. The cellular uptake of EGCG was examined using fluorescence (FITC)-labeled EGCG (FITC-EGCG) in combination with confocal microscopy.

RESULTS

The effect of EGCG on the growth of nHDFs depended on the concentration tested. At a low concentration (200 μmol/L), EGCG resulted in a slight decrease in the proportion of cells in the S and G(2)/M phases of cell cycle with a concomitant increase in the proportion of cells in G(0)/G(1) phase. At the higher doses (400 and 800 μmol/L), apoptosis was induced. The regulation of EGCG on the expression of pNF-κB was also concentration-dependent, whereas it did not affect the unphosphorylated NF-κB expression. cDNA microarray analysis showed that cell cycle-related genes were down-regulated by EGCG (200 μmol/L). The expression of cyclins A/B and cyclin-dependent kinase 1 was reversibly regulated by EGCG (200 μmol/L). FITC-EGCG was found to be internalized into the cytoplasm and translocated into the nucleus of nHDFs.

CONCLUSION

EGCG, through uptake into cytoplasm, reversibly regulated the cell growth and expression of cell cycle-related proteins and genes in normal fibroblasts.

Effect of (-)-epigallocatechin-3-gallate on maintaining the periodontal ligament cell viability of avulsed teeth: a preliminary study

PURPOSE

Avulsed tooth can be completely recovered, if sound periodontal ligament (PDL) of tooth is maintained. Although a lot of storage solutions have been explored for the better storage of avulsed tooth, there is a shortcoming that the preservation time is much short. On the other hand, there has been studies that (-)-epigallocatechin-3-gallate (EGCG), the most abundant polyphenol in green tea, which is related to the anti inflammatory, antioxygenic, and antibacterial effects, allows the successful preservations of tissues and cells. This study evaluated the effect of EGCG on avulsed-teeth preservation of Beagle dogs for a period of time.

METHODS

The atraumatically extracted teeth of Beagle dogs were washed and preserved with 0/10/100 µM of EGCG at the time of immediate, period 1 (4 days in EGCG-contained media and additional 1 day in EGCG-free media), period 2 (8 days in EGCG-contained media and additional 2 days in EGCG-free media) and period 3 (12 days in EGCG-contained media and additional 2 days in EGCG-free media). Then, the cell viabilities of preserved teeth was calculated by dividing optical density (OD) of 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay with OD of eosin assay to eliminate the measurement errors caused by the different tissue volumes.

RESULTS

From the results, the immediately analyzed group presented the highest cell viability, and the rate of living cells on teeth surface decreased dependent on the preservation period. However, the 100 µM of EGCG-treated group showed statistically significant positive cell activity than EGCG-free groups throughout preservation periods.

CONCLUSIONS

Our findings showed that 100 µM EGCG could maintain PDL cell viability of extracted tooth. These results suggest that although EGCG could not be a perfect additive for tooth preservation, it is able to postpone the period of tooth storage. However, further in-depth studies are required for more plausible use of EGCG.

Underlying mechanism for suppression of vascular smooth muscle cells by green tea polyphenol EGCG released from biodegradable polymers for stent application

Epigallocatechin-3-O-gallate (EGCG), the predominant catechin from tea, is known to exert a variety of cardiovascular beneficial effects by affecting the activity of receptor and signal transduction kinases. In this study, we investigated the suppressive effects of EGCG released from biodegradable poly(L-lactide-co-ε-caprolactone, PLCL) films on the proliferation, cell cycle progression and matrix metalloproteinase-2 (MMP-2) expression of vascular smooth muscle cells (VSMCs). The involvement of phosphorylated Akt (pAkt) and nuclear factor-κB (pNF-κB) as well as the internalization of EGCG into VSMCs was also examined as underlying mechanisms for EGCG-mediated VSMC inhibition. The proliferation of canine aortic SMCs (CASMCs) on EGCG-releasing PLCL (E-PLCL) was significantly inhibited. The culture of CASMCs on E-PLCL resulted in induction of cell cycle arrest at G(0)/G(1) phase and inactivation of pAkt, leading to subsequent apoptosis. Active MMP-2 expression was directly lowered by EGCG released from E-PLCL and indirectly inhibited by the EGCG-mediated suppression of pNF-κB. We also observed the incorporation of fluorescein isothiocyanate-conjugated EGCG into the cytoplasm of CASMCs and its further nuclear translocation, which could lead to the interruption of the exogenous signals directed to genes responsible for cellular responses of CASMCs. Taken together, the attenuated responses of VSMCs to E-PLCL were shown to be mediated through the suppression of pNF-κB, pAkt and each subsequent target genes or proteins by EGCG incorporated into the cells.

Potentiation of (-)-epigallocatechin-3-gallate-induced apoptosis by bortezomib in multiple myeloma cells

The green tea constituent, (-)-epigallocatechin-3-gallate (EGCG), has chemopreventive and anticancer effects. This is partially because of the selective ability of EGCG to induce apoptosis and death in cancer cells without affecting normal cells. In the present study, the activity of EGCG against the myeloma cell line, KM3, was examined. Our results demonstrated, for the first time, that the treatment of the KM3 cell line with EGCG inhibits cell proliferation and induces apoptosis, and there is a synergistic effect when EGCG and bortezomib are combined. Further experiments showed that this effect involves the NF-kappaB pathway. EGCG inhibits the expression of the P65 mRNA and P65/pP65 protein, meanwhile it downregulates pIkappaBalpha expression and upregulates IkappaBalpha expression. EGCG also activates caspase-3, -8, cleaved caspase-9, and poly-ADP-ribose polymerase (PARP) and subsequent apoptosis. These findings provided experimental evidence for efficacy of EGCG alone or in combination with bortezomib in multiple myeloma therapy.

Freeze-drying of mononuclear cells derived from umbilical cord blood followed by colony formation

BACKGROUND

We recently showed that freeze-dried cells stored for 3 years at room temperature can direct embryonic development following cloning. However, viability, as evaluated by membrane integrity of the cells after freeze-drying, was very low; and it was mainly the DNA integrity that was preserved. In the present study, we improved the cells' viability and functionality after freeze-drying.

METHODOLOGY/PRINCIPAL FINDINGS

We optimized the conditions of directional freezing, i.e. interface velocity and cell concentration, and we added the antioxidant EGCG to the freezing solution. The study was performed on mononuclear cells (MNCs) derived from human umbilical cord blood. After freeze-drying, we tested the viability, number of CD34(+)-presenting cells and ability of the rehydrated hematopoietic stem cells to differentiate into different blood cells in culture. The viability of the MNCs after freeze-drying and rehydration with pure water was 88%-91%. The total number of CD34(+)-presenting cells and the number of colonies did not change significantly when evaluated before freezing, after freeze-thawing, and after freeze-drying (5.4 x 10(4)+/-4.7, 3.49 x 10(4)+/-6 and 6.31 x 10(4)+/-12.27 cells, respectively, and 31+/-25.15, 47+/-45.8 and 23.44+/-13.3 colonies, respectively).

CONCLUSIONS

This is the first report of nucleated cells which have been dried and then rehydrated with double-distilled water remaining viable, and of hematopoietic stem cells retaining their ability to differentiate into different blood cells.