Viability measurements of hybridoma cells in suspension cultures

Engineering Vascularizing Electrospun Dermal Grafts by Integrating Fish Collagen and Ion-Doped Bioactive Glass

Utilizing bioactive molecules from organic sources in combination with inorganic materials for enhanced tissue regeneration has been a focus of recent scientific advancements. Some recent studies showed the potential of some specialized bioactive glass for healing of soft tissues; the role of Rohu (Labeo rohita) skin-derived collagen, a biopolymer in tissue regeneration and cutaneous healing, is yet to be established. So, we have fabricated four different types of electrospun mats as wound dressing materials/dermal grafts by combining locally sourced fish (Rohu) skin-derived collagen with novel composition of bioactive glass (Fcol/BAG) without and with dopants (3% and 5% Cu and Co, respectively and their binary) aimed at achieving an accelerated wound healing. FTIR and EDX mapping indicated successful integration of collagen and ion-doped bioactive glass in electrospun mats. Microfibers' architectural features and composition provided a cytocompatible and nontoxic environment conducive to adhesion, spreading, and proliferation of human dermal fibroblasts in vitro; in addition, they were hemocompatible with rabbit red blood cells. Better cutaneous wound healing in rabbits was achieved by treating with Fcol/CoBAG and Fcol/CuCoBAG microfibers with respect to improved wound closure, well-formed continuous epidermis, higher wound maturity, and regulated deposition of extracellular matrix components; mature collagen and elastin. Notably, a significantly (p < 0.01) higher density of blood vessels/positive CD 31 staining was observed in fish collagen/ion-doped bioactive glass microfibrous mat treated wounds suggesting efficient neo-vascularization during early stages of the healing process particularly attributable to copper and cobalt ions in the doped bioactive glass. Enhanced vascularizing ability of these engineered dermal composite grafts/wound dressings along with efficient remodeling of cutaneous structural components (ECM) could collectively be ascribed to bioactive properties of bioactive glass and stimulatory roles of copper, cobalt ions, and fish collagen. Our study demonstrates that a fish collagen/Cu and Co-doped bioactive glass microfibrous mat could potentially be used as a low-cost dressing material/dermal graft for augmented cutaneous wound healing.

Physiological and morphological response of Aphanizomenon flos-aquae to watermelon (Citrullus lanatus) peel aqueous extract

Natural algaecides are more likely to be specific and biodegradable, and may offer an environmentally friendly method for control of cyanobacterial blooms. We explored, for the first time, the potential for watermelon peel aqueous extract (WMPAE) to control the growth of the harmful blue-green alga Aphanizomenon flos-aquae. The growth inhibition and several physiological parameters of A. flos-aquae, in response to WMPAE, were analyzed. Results showed that WMPAE significantly inhibited the growth of A. flos-aquae in a concentration-dependent way. The highest inhibition reached 94 % after 3 days' treatment with 6 g L^-1 of WMPAE and a significant effect was obtained with lower doses and shorter times as well. The cell viability decreased quickly, cell shape changed, and intracellular structural damage occurred. At the same time, the antioxidant enzymes (superoxide dismutase SOD, catalase CAT and peroxidase POD) and malondialdehyde (MDA) levels all increased significantly, indicating that WMPAE between 2-6 g L^-1 induced severe oxidative stress and damage to A. flos-aquae. Moreover, production of the four pigments chlorophyll a (Chl a), carotenoids, phycocyanin (PC), and allophycocyanin (APC) were all stimulated, though photosynthesis of A. flos-aquae was clearly inhibited. The maximum quantum yield of photosystem II (F_v/F_m) and the effective quantum yield of photosystem II ( F_v^'/F_m^') declined sharply, suggesting the decreased photosystem capacity of A. flos-aquae to convert light energy into chemical energy. In addition, non-photochemical quenching (NPQ) of A. flos-aquae increased after a very short time exposure to WMPAE, and decreased significantly with prolonged exposure time, which indicated the failure of photo protection mechanisms. These results suggest that the loss of cell viability, and increases in oxidative stress, and damage to intracellular structure and photosynthetic systems might be the mechanisms for the inhibitory effects. Our results suggested that WMPAE could be a novel and effective approach for controlling the growth of A. flos-aquae in aquatic environments.

The development of the cell cryopreservation protocol with controlled rate thawing

Thawing in the water bath is often considered as a standard procedure. The thermal history of samples thawed in this way is poorly controlled, but cryopreservation and banking of cell-based products require standardization, automation and safety of all the technological stages including thawing. The programmable freezers allow implementation of the controlled cooling as well as the controlled thawing. As the cell damage occurs during the phase transformation that takes place in the cryoprotectant medium in the process of freezing-thawing, the choice of warming rates within the temperature intervals of transformations is very important. The goal of the study was to investigate the influence of warming rates within the intervals of the phase transformations in the DMSO-based cryoprotectant medium on the cell recovery and to develop a cryopreservation protocol with controlled cooling and warming rates. The temperature intervals of phase transformations such as melting of the eutectic mixture of the cryoprotectant solution (MEMCS), melting of the eutectic salt solution (MESS), melting of the main ice mass (MMIM), recrystallization before MEMCS, recrystallization before MESS and recrystallization before MMIM were determined by thermo-mechanical analysis. The biological experiments were performed on the rat testicular interstitial cells (TIC). The highest levels of the cell recovery and metabolic activity after cryopreservation were obtained using the protocol with the high (20 °C/min) warming rate in the temperature intervals of crystallization of the eutectics as well as recrystallizations and the low (1 °C/min) warming rate in the temperature intervals of melting of the eutectics as well as MMIM. The total cell recovery was 65.3 ± 2.1 %, the recovery of the 3-beta-HSD-positive (Leydig) cells was 82.9 ± 1.8 %, the MTT staining was 32.5 ± 0.9 % versus 42.1 ± 1.7 %; 57.4 ± 2.1 % and 24.0 ± 1.1 % respectively, when compared to the thawing in the water bath.

Assessment of cell viability

Cell viability may be judged by morphological changes or by changes in membrane permeability and/or physiological state inferred from the exclusion of certain dyes or the uptake and retention of others. This unit presents methods based on dye exclusion, esterase activity, and mitochondrial membrane potential, as well as protocols for determining the pre-fixation viability of fixed cells either before or after fixation with amine-reactive dyes suitable for a range of excitation wavelengths. Membrane-impermeable dead cell and live cell dyes as well as dye-exclusion procedures for microscopy are also included.

Inhibition of NF-κB-mediated transcription and induction of apoptosis by melampolides and repandolides

PURPOSE

Nuclear factor-kappaB (NF-kappaB) plays a crucial role in the regulation of inflammatory processes, cell proliferation, and apoptosis. Blocking NF-kappaB signaling may represent a therapeutic strategy in cancer and inflammation therapy. The aim of this study was to investigate the effects of sesquiterpenes isolated from Asteraceae, namely melampolides (enhydrin, tetraludin A) and repandolides (repandins A, B, D and E) on the activation of NF-kappaB, cell growth of cancer cells, cell cycle progression and apoptosis. In addition, their effects on the activity of cyclooxygenase-2 (COX-2) enzyme were also evaluated.

METHODS

Cell-based reporter gene assay was conducted in SW1353 cells. COX-2 enzyme activity and cell growth inhibition was determined by enzyme immunoassay and MTT assay respectively. Cell cycle analysis was carried out by flow cytometry and apoptosis was observed by DAPI staining assay.

RESULTS

In SW1353 cells, transcription mediated by NF-kappaB was inhibited by enhydrin, tetraludin A and repandins A, B, D and E, while Sp-1 mediated transcription was not affected. COX-2 enzyme activity was inhibited by enhydrin, repandin A and E, but not by tetraludin A, repandin B and D. These compounds were effective in inhibiting the growth of a panel of human tumor cell lines in a concentration-dependent manner. Cell cycle analysis and DAPI staining indicated cell cycle arrest in G(2)/M phase and induction of apoptosis.

CONCLUSIONS

Enhydrin, tetraludin A and repandins A, B, D and E inhibited tumor cell growth and induced cell cycle arrest and apoptosis. These effects may be related to inhibition of NF-B activation.

Phagocytosis and phagosomal fate of surface-modified microparticles in dendritic cells and macrophages

PURPOSE

We compared cationic, polyamine-coated microparticles (MPs) and anionic, protein-coated MPs with respect to their phagocytosis and phagosomal fate in dendritic cells (DCs) and macrophages (Mphi).

METHODS

Polystyrene MPs were surface modified by covalent coupling with fluorescein isothiocyanate-labeled polyamines or proteins. Phagocytosis of MP and the pH of their intracellular microenvironment was assessed in human-derived DCs and Mphi in a fluorescence plate reader. Visualization of MP phagocytosis in DCs was performed by transmission electron microscopy.

RESULTS

Phagocytosis of bovine serum albumin-coated MPs was low with significant differences between DC and Mphi, whereas phagocytosis of IgG-coated MPs was significantly enhanced in both cell types. Phagocytosis of both particle types resulted in an acidified phagosomal microenvironment (pH 4.6-5.1). In contrast, cationic, polyamine-coated MPs were equally phagocytosed by DCs and Mphi to a high extent and showed lower degrees of acidification (pH 6.0-6.8) in the phagosomal microenvironment. Transmission electron microscopy examination demonstrated all phagocytosed particles to be surrounded by a phagosomal membrane, which was more tightly apposed to the surface of cationic MPs and more loosely to bovine serum albumin-coated MPs.

CONCLUSION

Phagocytosis of cationic, polyamine-coated MPs is suggested to lead to diminished phagosomal acidification. Thus, cationic MP are potential carriers that may display beneficial features for the intracellular delivery of immunomodulating therapeutics and their protection against lysosomal degradation.

Dynamic recording of cell death in the in vitro dorsal vagal nucleus of rats in response to metabolic arrest

Anoxic/ischemic neuronal death is usually assessed in cell cultures or in vivo within a time window of 24 h to several days using the nucleic acid stain propidium iodide or histological techniques. Accordingly, there is limited information on the time course of such neuronal death. We loaded acute rat brain stem slices with propidium iodide for dynamic fluorometric recording of metabolic arrest-related cell death in the dorsal vagal nucleus. This model was chosen because dorsal vagal neurons show a graded response to metabolic inhibition: anoxia and aglycemia cause a sustained hyperpolarization, whereas ischemia induces a glutamate-mediated, irreversible depolarization. We found that the number of propidium iodide-labeled cells increased from 27% to 43% of total cell count within 1-7 h after preparation of slices. Compared with these untreated control slices, cyanide-induced anoxia (30 min) or aglycemia (1 h) did not cause further cell death, whereas 3-h aglycemia destroyed an additional 13% of cells. Ischemia (1 h) due to cyanide plus iodoacetate immediately labeled an additional 20% of cells, and an additional 48% of cells were destroyed within the following 3 h of postischemia. Continuous recording of propidium iodide fluorescence showed that loss of membrane integrity started within 25 min after onset of the ischemic depolarization and the concomitant intracellular Ca(2+) rise. The results show that propidium iodide can be used to monitor cell death in acute brain slices. Our findings suggest that pronounced cell death occurs within a period of 1-4 h after onset of metabolic arrest and is apparently due to necrotic/oncotic mechanisms.

Progressive disruption of the plasma membrane during renal proximal tubule cellular injury

The goal of this study was to examine the progression of plasma membrane disruption during cell injury using rabbit renal proximal tubules (RPT). The results demonstrated that the plasma membrane became permeable to larger and larger molecules as anoxia proceeded. At least three distinctive phases of membrane disruption were differentiated during anoxia. In phases 1, 2, and 3, plasma membranes became permeable to propidium iodide (PI, molecular weight = 668), 3 kDa dextrans, and 70 kDa dextrans or lactate dehydrogenase (LDH, molecular weight = 140 kDa), respectively. Phase 1 was reversible by reoxygenation but not prevented by the glycine. Phase 2 was inhibited by glycine. Phase 3 was inhibited by several membrane-permeable homobifunctional crosslinkers, dimethyl-pimelimidate (DMP), ethylene-glycolbis(succinimidylsuccinate), and dithiobis(succinimidylpropionate), but not by the membrane-impermeable crosslinker dithiobis(sulfosuccinimidylpropionate). In addition, DMP decreased RPT LDH release produced by mitochondrial inhibition (antimycin A), an oxidant (t-butylhydroperoxide) and a nephrotoxicant that is metabolized to an electrophile (tetrafluoroethyl-l-cysteine). These results identify (1) different phases of plasma membrane damage with increasing permeability during cell injury, (2) the reversibility of phase 1, (3) the relative site of action of the cytoprotectant glycine (prevents phase 2), and (4) the protective effects of chemical crosslinkers in RPT cell death produced by different toxicants.

Increased Sensitivity of Acute Myeloid Leukemias to Lovastatin-Induced Apoptosis: A Potential Therapeutic Approach

We recently demonstrated that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme of de novo cholesterol synthesis, was a potential mediator of the biological effects of retinoic acid on human neuroblastoma cells. The HMG-CoA reductase inhibitor, lovastatin, which is used extensively in the treatment of hypercholesterolemia, induced a potent apoptotic response in human neuroblastoma cells. This apoptotic response was triggered at lower concentrations and occurred more rapidly than had been previously reported in other tumor-derived cell lines, including breast and prostate carcinomas. Because of the increased sensitivity of neuroblastoma cells to lovastatin-induced apoptosis, we examined the effect of this agent on a variety of tumor cells, including leukemic cell lines and primary patient samples. Based on a variety of cytotoxicity and apoptosis assays, the 6 acute lymphocytic leukemia cell lines tested displayed a weak apoptotic response to lovastatin. In contrast, the majority of the acute myeloid leukemic cell lines (6/7) and primary cell cultures (13/22) showed significant sensitivity to lovastatin-induced apoptosis, similar to the neuroblastoma cell response. Of significance, in the acute myeloid leukemia, but not the acute lymphocytic leukemia cell lines, lovastatin-induced cytotoxicity was pronounced even at the physiological relevant concentrations of this agent. Therefore, our study suggests the evaluation of HMG-CoA reductase inhibitors as a therapeutic approach in the treatment of acute myeloid leukemia.

Increased Sensitivity of Acute Myeloid Leukemias to Lovastatin-Induced Apoptosis: A Potential Therapeutic Approach

We recently demonstrated that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme of de novo cholesterol synthesis, was a potential mediator of the biological effects of retinoic acid on human neuroblastoma cells. The HMG-CoA reductase inhibitor, lovastatin, which is used extensively in the treatment of hypercholesterolemia, induced a potent apoptotic response in human neuroblastoma cells. This apoptotic response was triggered at lower concentrations and occurred more rapidly than had been previously reported in other tumor-derived cell lines, including breast and prostate carcinomas. Because of the increased sensitivity of neuroblastoma cells to lovastatin-induced apoptosis, we examined the effect of this agent on a variety of tumor cells, including leukemic cell lines and primary patient samples. Based on a variety of cytotoxicity and apoptosis assays, the 6 acute lymphocytic leukemia cell lines tested displayed a weak apoptotic response to lovastatin. In contrast, the majority of the acute myeloid leukemic cell lines (6/7) and primary cell cultures (13/22) showed significant sensitivity to lovastatin-induced apoptosis, similar to the neuroblastoma cell response. Of significance, in the acute myeloid leukemia, but not the acute lymphocytic leukemia cell lines, lovastatin-induced cytotoxicity was pronounced even at the physiological relevant concentrations of this agent. Therefore, our study suggests the evaluation of HMG-CoA reductase inhibitors as a therapeutic approach in the treatment of acute myeloid leukemia.

Effects of H2O2 on the growth, secretion, and metabolism of hybridoma cells in culture

The effect of low concentrations of hydrogen peroxide (H2O2) (5 x 10(-7)-9.5 x 10(-7) M) on cell growth and antibody production was investigated with murine hybridoma cells (Mark 3 and anti-hPL) in culture. Cell growth, measured by flow cytometry with morphological parameters, was significantly stimulated by H2O2 (8 x 10(-7) M) but H2O2 concentration of 7 x 10(-6) M and above increased cell death. H2O2 stimulation of antibody production was nonsignificant. The metabolism of cells treated with 8 x 10(-7) or 1 x 10(-5) M H2O2 was similar to that of the control in terms of glucose and glutamine consumption, lactate and ammonia production, and amino acid concentrations in the medium. The concentrations of lactate dehydrogenase, a marker of cell death, in test and control cells were similar. However, concentrations of intracellular free radicals measured by flow cytometry with dihydrorhodamine 123 (DHR 123) and dichlorofluorescein diacetate (DCFH-DA) as fluorochromes were different. The reactive oxygen species content of cells in 8 x 10(-7) M H2O2 was similar to that of the controls, but there was a sudden, marked production of superoxide anions (detected with DHR 123) and H2O2 or peroxides (detected with DCFH-DA) by cells incubated with 1 x 10(-5) M H2O2 which increased with increasing H2O2 until cell death.

Determination of the time course and extent of neurotoxicity at defined temperatures in cultured neurons using a modified multiwell plate fluorescence scanner

The cellular and molecular mechanisms of hypoxic/ischemic neurodegeneration are sensitive to numerous factors that modulate the time course and degree of neuronal death. Among such factors is hypothermia, which can dramatically protect neurons from injury. To examine and control for temperature-dependent effects, we developed a technique that provides for a high-throughput, accurate, and reproducible determination of the time course and degree of neurotoxicity in cultured cortical neurons at precisely defined temperatures. We used a fluorescence multiwell plate scanner, modified by us to permit the control of temperature, to perform serial quantitative measurements of propidium iodide (PI) fluorescence in cortical neuronal cultures exposed to excitotoxic insults. In validating this approach, we show that these time course measurements correlate highly with manual counts of PI-stained cells in the same cultures (r = 0.958, p < 0.0001) and with lactate dehydrogenase release (r = 0.964, p < 0.0001). This method represents an efficient approach to mechanistic and quantitative studies of cell death as well as a high-throughput technique for screening new neuroprotective therapies in vitro.

The determination of cellular viability of hybridoma cells in microtitre plates: a colorimetric assay based on neutral red

A colorimetric assay utilising Neutral Red (C.I. 50040), a nuclear stain, was developed to determine the cellular viability of hybridoma cells in microtitre plates. A linear correlation (r = 0.99) was found to exist between the uptake of Neutral Red by viable cells and the viable cell count determined by Trypan blue exclusion test. The linearity stretched over the range of cell concentrations normal in batch cultures (2-30 x 10(4)/0.2 ml) with as little as +/- 6% intra-plate well-to-well variation and +/- 10.2% inter-assay variation. Microscopical examinations of viable hybridoma cells stained with Neutral Red showed that it was located in the nucleus. The possible bifunctional activity of the Neutral Red assay as a test for cellular viability and estimating the DNA content of hybridoma cells is discussed along with its application in a drug screening programme.