Measurement of cell death in mammalian cells

Identification of a pore-forming protein from sea anemone Anthopleura dowii Verrill (1869) venom by mass spectrometry

Background:

Pore-forming proteins (PFP) are a class of toxins abundant in the venom of sea anemones. Owing to their ability to recognize and permeabilize cell membranes, pore-forming proteins have medical potential in cancer therapy or as biosensors. In the present study, we showed the partial purification and sequencing of a pore-forming protein from Anthopleura dowii Verrill (1869). 17.

Methods:

Cytolytic activity of A. dowii Verrill (1869) venom was determined via hemolysis assay in the erythrocytes of four mammals (sheep, goat, human and rabbit). The cytotoxic activity was analyzed in the human adherent lung carcinoma epithelial cells (A549) by the cytosolic lactate dehydrogenase (LDH) assay, and trypan blue staining. The venom was fractionated via ammonium sulfate precipitation gradient, dialysis, and ion exchange chromatography. The presence of a pore-forming protein in purified fractions was evaluated through hemolytic and cytotoxic assays, and the activity fraction was analyzed using the percent of osmotic protections after polyethylene glycol (PEG) treatment and mass spectrometry. 18.

Results:

The amount of protein at which the venom produced 50% hemolysis (HU₅₀) was determined in hemolysis assays using erythrocytes from sheep (HU₅₀ = 10.7 ± 0.2 μg), goat (HU₅₀ = 13.2 ± 0.3 μg), rabbit (HU₅₀ = 34.7 ± 0.5 μg), and human (HU₅₀ = 25.6 ± 0.6 μg). The venom presented a cytotoxic effect in A549 cells and the protein amount present in the venom responsible for producing 50% death (IC₅₀) was determined using a trypan blue cytotoxicity assay (1.84 ± 0.40 μg/mL). The loss of membrane integrity in the A549 cells caused by the venom was detected by the release of LDH in proportion to the amount of protein. The venom was fractionated; and the fraction with hemolytic and cytotoxic activities was analyzed by mass spectrometry. A pore-forming protein was identified. The cytotoxicity in the A549 cells produced by the fraction containing the pore-forming protein was osmotically protected by PEG-3350 Da molecular mass, which corroborated that the loss of integrity in the plasma membrane was produced via pore formation. 19. Conclusion: A. dowii Verrill (1869) venom contains a pore-forming protein suitable for designing new drugs for cancer therapy.

Preparation and optimization of monodisperse polymeric microparticles using modified vibrating orifice aerosol generator for controlled delivery of letrozole in breast cancer therapy

Letrozole (LTZ) is effective for the treatment of hormone-receptor-positive breast cancer in postmenopausal women. In this work, and for the first time, using vibrating orifice aerosol generator (VOAG) technology, monodisperse poly-ε-caprolactone (PCL), and poly (D, L-Lactide) (PDLLA) LTZ-loaded microparticles were prepared and found to elicit selective high cytotoxicity against cancerous breast cells with no apparent toxicity on healthy cells in vitro. Plackett-Burman experimental design was utilized to identify the most significant factors affecting particle size distribution to optimize the prepared particles. The generated microparticles were characterized in terms of microscopic morphology, size, zeta potential, drug entrapment efficiency, and release profile over one-month period. Long-term cytotoxicity of the microparticles was also investigated using MCF-7 human breast cancer cell lines in comparison with primary mammary epithelial cells (MEC). The prepared polymeric particles were monodispersed, spherical, and apparently smooth, regardless of the polymer used or the loaded LTZ concentration. Particle size varied from 15.6 to 91.6 µm and from 22.7 to 99.6 µm with size distribution (expressed as span values) ranging from 0.22 to 1.24 and from 0.29 to 1.48 for PCL and PDLLA based microparticles, respectively. Upon optimizing the manufacture parameters, span was reduced to 0.162-0.195. Drug entrapment reached as high as 96.8%, and drug release from PDLLA and PCL followed a biphasic zero-order release using 5 or 30% w/w drug loading in the formulations. Long-term in vitro cytotoxicity studies indicated that microparticles formulations significantly inhibited the growth of MCF-7 cell line over a prolonged period of time but did not have toxic effects on the normal breast epithelial cells.

Co-delivery of Docetaxel and Disulfonate Tetraphenyl Chlorin in One Nanoparticle Produces Strong Synergism between Chemo- and Photodynamic Therapy in Drug-Sensitive and -Resistant Cancer Cells

Cancer therapies based on the combinations of different drugs and/or treatment modalities are emerging as important strategies for increasing efficacy and cure, decreasing unwanted toxicity, and overcoming drug resistance, provided that optimized drug concentration ratios are delivered into the target tissue. To these purposes, delivery systems such as nanoparticles (NPs) offer the unique opportunity to finely tune the drug loading and the release rate of drug combinations in the target tissues. Here, we propose double-layered polymeric NPs for the delivery of the chemotherapeutic docetaxel (DTX) and the photosensitizer disulfonate tetraphenyl chlorin (TPCS2a) coated with hyaluronic acid (HA), which allows cell targeting via CD44 receptors. The simultaneous delivery of the two drugs aims at killing DTX-sensitive (HeLa-P, MDA-MB-231) and DTX-resistant (HeLa-R) cancer cells by combining chemotherapy and photodynamic therapy (PDT). Using the Chou and Talalay method that analyses drug interactions and calculates combination index (CI) using the median-effect principle, we compared the efficiency of DTX chemotherapy combined with TPCS2a-PDT for drugs delivered in the standard solvents, coloaded in the same NP (DTX/TPCS2a-NP) or loaded in separate NPs (DTX-NPs + TPCS2a-NPs). Along with the drug interaction studies, we gained insight into cell death mechanisms after combo-therapy and into the extent of TPCS2a intracellular uptake and localization. In all cell lines considered, the analysis of the viability data revealed synergistic drug/treatment interaction especially when DTX and TPCS2a were delivered to cells coloaded in the same NPs despite the reduced PS uptake measured in the presence of the delivery systems. In fact, while the combinations of the free drugs or drugs in separate NPs gave slight synergism (CI < 1) only at doses killing more than 50% of the cells, the combination of drugs in one NPs gave high synergism also at doses killing 10-20% of the cells. Furthermore, the DTX dose in the combination DTX/TPCS2a-NPs could be reduced by ∼2.6- and 10.7-fold in HeLa-P and MDA-MB-231, respectively. Importantly, drug codelivery in NPs was very efficient in inducing cell mortality also in DTX resistant HeLa-R cells overexpressing P-glycoprotein 1 in which the dose of the chemotherapeutic can be reduced by more than 100 times using DTX/TPCS2a-NPs. Overall, our data demonstrate that the protocol for the preparation of HA-targeted double layer polymeric NPs allows to control the concentration ratio of coloaded drugs and the delivery of the transported drugs for obtaining a highly synergistic interaction combining DTX-chemotherapy and TPCS2a-PDT.

Chrysin disrupts intracellular homeostasis through mitochondria-mediated cell death in human choriocarcinoma cells

The trophoblast cells which form the placenta, have a high potential for invading other tissues. Owing to certain mechanisms, trophoblast cells may lose their ability to control cell proliferation, and develop into pregnancy-related tumors, known as choriocarcinomas. Choriocarcinomas mostly develop from the hydatidiform mole, which is frequently found in pregnant women. Owing to their ability to rapidly metastasize through the hematogenous route, choriocarcinomas are very hard to cure if not detected at the proper time. Although numerous studies are attempting to identify the major pathways in choriocarcinoma cells, the critical pathway responsible for the origin of choriocarcinomas is still unclear. In this study, we identified that chrysin has inhibitory effects on human choriocarcinoma cells. The study demonstrated that chrysin disrupts intracellular homeostasis by altering the mitochondrial membrane potential (MMP), cytosolic Ca²⁺ levels, production of reactive oxygen species (ROS), and lipid peroxidation, leading to the death of choriocarcinoma cells (JAR and JEG3). Additionally, the effects of chrysin on choriocarcinoma cells were found to be mediated via the regulation of the AKT, ERK1/2, and JNK signaling pathways. Altogether, the anti-cancer effects of chrysin can aid the development of a novel therapeutic strategy against the progression of human choriocarcinomas.

4-Hydroxy-7-oxo-5-heptenoic Acid Lactone Is a Potent Inducer of the Complement Pathway in Human Retinal Pigmented Epithelial Cells

We previously discovered that oxidative cleavage of docosahexaenoate (DHA), which is especially abundant in the retinal photoreceptor rod outer segments and retinal pigmented endothelial (RPE) cells, generates 4-hydroxy-7-oxo-5-heptenoate (HOHA) lactone, and that HOHA lactone can enter RPE cells that metabolize it through conjugation with glutathione (GSH). The consequent depletion of GSH results in oxidative stress. We now find that HOHA lactone induces upregulation of the antioxidant transcription factor Nrf2 in ARPE-19 cells. This leads to expression of GCLM, HO1, and NQO1, three known Nrf2-responsive antioxidant genes. Besides this protective response, HOHA lactone also triggers a countervailing inflammatory activation of innate immunity. Evidence for a contribution of the complement pathway to age-related macular degeneration (AMD) pathology includes the presence of complement proteins in drusen and Bruch's membrane from AMD donor eyes, and the identification of genetic susceptibility loci for AMD in the complement pathway. In eye tissues from a mouse model of AMD, accumulation of complement protein in Bruch's membrane below the RPE suggested that the complement pathway targets this interface, where lesions occur in the RPE and photoreceptor rod outer segments. In animal models of AMD, intravenous injection of NaIO₃ to induce oxidative injury selectively destroys the RPE and causes secretion of factor C3 from the RPE into areas directly adjacent to sites of RPE damage. However, a molecular-level link between oxidative injury and complement activation remained elusive. We now find that sub-micromolar concentrations of HOHA lactone foster expression of C3, CFB, and C5 in ARPE-19 cells and induce a countervailing upregulation of CD55, an inhibitor of C3 convertase production and complement cascade amplification. Ultimately, HOHA lactone causes membrane attack complex formation on the plasma membrane. Thus, HOHA lactone provides a molecular-level connection between free-radical-induced oxidative cleavage of DHA and activation of the complement pathway in AMD pathology.

New Three-Dimensional Poly(decanediol-co-tricarballylate) Elastomeric Fibrous Mesh Fabricated by Photoreactive Electrospinning for Cardiac Tissue Engineering Applications

Reactive electrospinning is capable of efficiently producing in situ crosslinked scaffolds resembling the natural extracellular matrix with tunable characteristics. In this study, we aimed to synthesize, characterize, and investigate the in vitro cytocompatibility of electrospun fibers of acrylated poly(1,10-decanediol-co-tricarballylate) copolymer prepared utilizing the photoreactive electrospinning process with ultraviolet radiation for crosslinking, to be used for cardiac tissue engineering applications. Chemical, thermal, and morphological characterization confirmed the successful synthesis of the polymer used for production of the electrospun fibrous scaffolds with more than 70% porosity. Mechanical testing confirmed the elastomeric nature of the fibers required to withstand cardiac contraction and relaxation. The cell viability assay showed no significant cytotoxicity of the fibers on cultured cardiomyoblasts and the cell-scaffolds interaction study showed a significant increase in cell attachment and growth on the electrospun fibers compared to the reference. This data suggests that the newly synthesized fibrous scaffold constitutes a promising candidate for cardiac tissue engineering applications.

Effects of Amyloid-β Peptide on the Biology of Human Neural Stem Cells

The amyloid -β peptide (Aβ) is the main component of the amyloid plaques in Alzheimer's disease (AD). It has been widely demonstrated that Aβ is toxic to neurons and is associated with AD pathology. However, Aβ also appears to have an important biological function both in the adult brain and throughout embryonic development of the nervous system, acting as a trophic factor at low concentrations.It is known that Neural Stem Cells (NSCs) are capable of self-renewal and differentiate into functional glial and neuronal cells. Therefore, human NSCs may be a hope for future therapeutic application in neurodegenerative diseases such as AD. The effects of Aβ peptides on NSCs are still not well understood and remain controversial.In this chapter we outline the materials and methods used for the culture and differentiation of hNS1 cells, a cell line of human NSCs. We describe the preparation of different forms (monomeric, oligomeric and fibrillary) of Aβ peptide and subsequent cell treatment, followed by the analysis of the effects on toxicity, cell proliferation and cell fate specification of hNS1 cells.

Preparation of A Spaceflight: Apoptosis Search in Sutured Wound Healing Models

To prepare the ESA (European Space Agency) spaceflight project "Wound healing and Sutures in Unloading Conditions", we studied mechanisms of apoptosis in wound healing models based on ex vivo skin tissue cultures, kept for 10 days alive in serum-free DMEM/F12 medium supplemented with bovine serum albumin, hydrocortisone, insulin, ascorbic acid and antibiotics at 32 °C. The overall goal is to test: (i) the viability of tissue specimens; (ii) the gene expression of activators and inhibitors of apoptosis and extracellular matrix components in wound and suture models; and (iii) to design analytical protocols for future tissue specimens after post-spaceflight download. Hematoxylin-Eosin and Elastica-van-Gieson staining showed a normal skin histology with no signs of necrosis in controls and showed a normal wound suture. TdT-mediated dUTP-biotin nick end labeling for detecting DNA fragmentation revealed no significant apoptosis. No activation of caspase-3 protein was detectable. FASL, FADD, CASP3, CASP8, CASP10, BAX, BCL2, CYC1, APAF1, LAMA3 and SPP1 mRNAs were not altered in epidermis and dermis samples with and without a wound compared to 0 day samples (specimens investigated directly post-surgery). BIRC5, CASP9, and FN1 mRNAs were downregulated in epidermis/dermis samples with and/or without a wound compared to 0 day samples. BIRC2, BIRC3 were upregulated in 10 day wound samples compared to 0 day samples in epidermis/dermis. RELA/FAS mRNAs were elevated in 10 day wound and no wound samples compared to 0 day samples in dermis. In conclusion, we demonstrate that it is possible to maintain live skin tissue cultures for 10 days. The viability analysis showed no significant signs of cell death in wound and suture models. The gene expression analysis demonstrated the interplay of activators and inhibitors of apoptosis and extracellular matrix components, thereby describing important features in ex vivo sutured wound healing models. Collectively, the performed methods defining analytical protocols proved to be applicable for post-flight analyzes of tissue specimens after sample return.

Andrographolide enhanced 5-fluorouracil-induced antitumor effect in colorectal cancer via inhibition of c-MET pathway

Colorectal cancer (CRC) is the third most common malignant neoplasm worldwide. 5-Fluorouracil (5-Fu) is the most important chemotherapeutic drug used for the treatment of CRC. However, resistance to 5-Fu therapies is a growing concern in CRC clinical practice recently. Andrographolide (Andro) is a main bioactive constituent of the herb Andrographis paniculata, which has various biological effects including anti-inflammation and antitumor activities. In the present study, we investigated the effects of combined Andro with 5-Fu against CRC HCT-116 cells. In vitro studies showed that Andro synergistically enhanced the anti-proliferation effect of 5-Fu on HCT-116 cells due to increased apoptotic cells. Meanwhile, results of the enzyme linked immunosorbent assay indicated that the level of phosphorylated cellular-mesenchymal to epithelial transition factor (p-MET) was decreased by the combination treatment. Further study suggested that Andro promoted the antitumor effect of 5-Fu by down-regulating the level of p-MET. In conclusion, these results confirmed the synergistic antitumor activity of Andro on CRC and provide evidence for possible clinical application of Andro for enhancing the antitumor effect of 5-Fu in CRC treatment.

Mild external heating and reduction in spontaneous contractions of the bladder

OBJECTIVES

To measure the effect of external heating on bladder wall contractile function, histological structure and expression of proteins related to tissue protection and apoptosis.

MATERIAL AND METHODS

In vitro preparations of bladder wall and ex vivo perfused pig bladders were heated from 37 to 42°C, 46 and 50°C for 15 min. Isolated preparations were heated by radiant energy and perfused bladders were heated by altering perfusate temperature. Spontaneous contractions or pressure variations were recorded, as well as responses to the muscarinic agonist carbachol or motor nerve excitation in vitro during heating. Tissue histology in control and after heating was analysed using haematoxylin and eosin staining and 4'-6-diamidino-2-phenylindole (DAPI) nuclear labelling. The effects of heating on protein expression levels of (i) heat shock proteins HSP27-pSer82 and inducible-HSP70 and (ii) caspase-3 and its downstream DNA-repair substrate poly-[ADP-ribose] polymerase (PARP) were measured.

RESULTS

Heating to 42°C reduced spontaneous contractions or pressure variations by ~70%; effects were fully reversible. There were no effects on carbachol or nerve-mediated responses. Tissue histology was unaffected by heating, and expression of heat shock proteins as well as caspase-3 and PARP were also unaltered. A TRPV1 antagonist had no effect on the reduction of spontaneous activity. Heating to 46°C had a similar effect on spontaneous activity and also reduced the carbachol contracture. Urothelial structure was damaged, caspase-3 levels were increased and inducible-HSP70 levels declined. At 50°C evoked contractions were abolished, the urothelium was absent and heat shock proteins and PARP expression was reduced with raised caspase-3 expression.

CONCLUSIONS

Heating to 42°C caused a profound, reversible and reproducible attenuation of spontaneous activity, with no tissue damage and no initiation of apoptosis pathways. Higher temperatures caused tissue damage and activation of apoptotic mechanisms. Mild heating offers a novel approach to reducing bladder spontaneous activity.

Estimating Extrinsic Dyes for Fluorometric Online Monitoring of Antibody Aggregation in CHO Fed-Batch Cultivations

Multi-wavelength fluorescence spectroscopy was evaluated in this work as tool for real-time monitoring of antibody aggregation in CHO fed-batch cultivations via partial least square (PLS) modeling. Therefore, we used the extrinsic fluorescence dyes 1-anilinonaphthalene-8-sulfonate (ANS), 4,4′-bis-1-anilinonaphthalene-8-sulfonate (Bis-ANS), or Thioflavin T (ThT) as medium additives. This is a new application area, since these dyes are commonly used for aggregate detection during formulation development. We determined the half maximum inhibitory concentrations of ANS (203 ± 11 µmol·L⁻¹), Bis-ANS (5 ± 0.5 µmol·L⁻¹), and ThT (3 ± 0.2 µmol·L⁻¹), and selected suitable concentrations for this application. The results showed that the emission signals of non-covalent dye antibody aggregate interaction superimposed the fluorescence signals originating from feed medium and cell culture. The fluorescence datasets were subsequently used to build PLS models, and the dye-related elevated fluorescence signals dominated the model calibration. The soft sensors based on ANS and Bis-ANS signals showed high predictability with a low error of prediction (1.7 and 2.3 mg·mL⁻¹ aggregates). In general, the combination of extrinsic dye and used concentration influenced the predictability. Furthermore, the ThT soft sensor indicated that the intrinsic fluorescence of the culture might be sufficient to predict antibody aggregation online.

Acute death of astrocytes in blast-exposed rat organotypic hippocampal slice cultures

Blast traumatic brain injury (bTBI) affects civilians, soldiers, and veterans worldwide and presents significant health concerns. The mechanisms of neurodegeneration following bTBI remain elusive and current therapies are largely ineffective. It is important to better characterize blast-evoked cellular changes and underlying mechanisms in order to develop more effective therapies. In the present study, our group utilized rat organotypic hippocampal slice cultures (OHCs) as an in vitro system to model bTBI. OHCs were exposed to either 138 ± 22 kPa (low) or 273 ± 23 kPa (high) overpressures using an open-ended helium-driven shock tube, or were assigned to sham control group. At 2 hours (h) following injury, we have characterized the astrocytic response to a blast overpressure. Immunostaining against the astrocytic marker glial fibrillary acidic protein (GFAP) revealed acute shearing and morphological changes in astrocytes, including clasmatodendrosis. Moreover, overlap of GFAP immunostaining and propidium iodide (PI) indicated astrocytic death. Quantification of the number of dead astrocytes per counting area in the hippocampal cornu Ammonis 1 region (CA1), demonstrated a significant increase in dead astrocytes in the low- and high-blast, compared to sham control OHCs. However only a small number of GFAP-expressing astrocytes were co-labeled with the apoptotic marker Annexin V, suggesting necrosis as the primary type of cell death in the acute phase following blast exposure. Moreover, western blot analyses revealed calpain mediated breakdown of GFAP. The dextran exclusion additionally indicated membrane disruption as a potential mechanism of acute astrocytic death. Furthermore, although blast exposure did not evoke significant changes in glutamate transporter 1 (GLT-1) expression, loss of GLT-1-expressing astrocytes suggests dysregulation of glutamate uptake following injury. Our data illustrate the profound effect of blast overpressure on astrocytes in OHCs at 2 h following injury and suggest increased calpain activity and membrane disruption as potential underlying mechanisms.

Formulation of benzoxaborole drugs in PLLA: from materials preparation to in vitro release kinetics and cellular assays

A complete investigation on the incorporation of simple benzoxaboroles into PLLA-based films was carried out.

CARD9 mediates necrotic smooth muscle cell-induced inflammation in macrophages contributing to neointima formation of vein grafts

AIMS

Inflammation plays an important role in the neointima formation of grafted veins. However, the initiation of inflammation in grafted veins is still unclear. Here, we investigated the role and underlying mechanism of an innate immunity signalling protein, caspase-associated recruitment domain 9 (CARD9) in vein grafts in mice.

METHODS AND RESULTS

In early murine vein grafts, we observed robust death of smooth muscle cells (SMCs), which was accompanied by infiltration of macrophages and expression of pro-inflammatory cytokines. Meanwhile, SMC necrosis was associated with the expression of pro-inflammatory cytokines in macrophages in vitro. To explore the mediators of necrotic SMC-induced inflammation in grafted veins from mice, we examined the expression of CARD family proteins and found CARD9 highly expressed in infiltrated macrophages of grafted veins. CARD9-knockout (KO) inhibited necrotic SMC-induced pro-inflammatory cytokine expression and NF-κB activation. Furthermore, CARD9-KO suppressed necrotic SMC-induced expression of VEGF in macrophages. Finally, CARD9-KO decreased neointima formation of grafted veins in mice.

CONCLUSION

The innate immune protein CARD9 in macrophages may mediate necrotic SMC-induced inflammation by activating NF-κB and contributed to neointima formation in the vein grafts.