Automated analysis and survival selection of anchorage-dependent cells under normal growth conditions

Novel millimeter-wave-based method for in situ cell isolation and other applications

As an alternative to laser-based methods, we developed a novel in situ cell isolation method and instrument based on local water absorption of millimeter wave (MMW) radiation that occurs in cellular material and nearby culture medium while the cultureware materials (plastic and glass) are transparent to MMW frequencies. Unwanted cells within cell population are targeted with MMWs in order to kill them by overheating. The instrument rapidly (within 2-3 seconds) heats a cell culture area of about 500 µm in diameter to 50 °C using a low-power W-band (94 GHz) MMW source. Heated cells in the area detach from the substrate and can be removed by a media change leaving a bare spot. Hence we named the instrument "CellEraser". Quick, local and non-contact heating with sharp boundaries of the heated area allows elimination of the unwanted cells without affecting the neighboring cells. The instrument is implemented as a compact microscope attachment and the selective hyperthermic treatment can be done manually or in an automated mode. Mammalian cells heated even momentarily above 50 °C will not survive. This "temperature of no return" does not compromise cellular membranes nor does it denature proteins. Using the CellEraser instrument we found that the key event that determines the fate of a cell at elevated temperatures is whether or not the selectivity of its nucleus is compromised. If a cell nucleus becomes "leaky" allowing normally excluded (cytoplasmic) proteins in and normally nuclear-localized proteins out, that cell is destined to die. Quick heating by MMWs to higher temperatures (70 °C) denatures cellular proteins but the cells are not able to detach from the substrate - instead they undergo a phenomenon we called "thermofixation": such cells look similar to cells fixed with common chemical fixatives. They remain flat and are not washable from the substrate. Interestingly, their membranes become permeable to DNA dyes and even to antibodies. Thermofixation allows the use of western blot antibodies for immunofluorescence imaging.

Isolation of single mammalian cells from adherent cultures by fluidic force microscopy

The physical separation of individual cells from cell populations for single-cell analysis and proliferation is of wide interest in biology and medicine. Today, single-cell isolation is routinely applied to non-adherent cells, though its application to cells grown on a substrate remains challenging. In this report, a versatile approach for isolating single HeLa cells directly from their culture dish is presented. Fluidic force microscopy is first used to detach the targeted cell(s) via the tunable delivery of trypsin, thereby achieving cellular detachment with single-cell resolution. The cell is then trapped by the microfluidic probe via gentle aspiration, displaced with micrometric precision and either transferred onto a new substrate or deposited into a microwell. An optimised non-fouling coating ensures fully reversible cell capture and the potential for serial isolation of multiple cells with 100% successful transfer rate (n = 130) and a survival rate of greater than 95%. By providing an efficient means for isolating targeted adherent cells, the described approach offers exciting possibilities for biomedical research.

Methods of cell purification: a critical juncture for laboratory research and translational science

Research in cell biology and the development of translational technologies are driven by competition, public expectations, and regulatory oversight, putting these fields at a critical juncture. Success in these fields is quickly becoming dependent on the ability of researchers to identify and isolate specific cell populations from heterogeneous mixtures accurately and efficiently. Many methods for cell purification have been developed, and each has advantages and disadvantages that must be considered in light of the intended application. Current cell separation strategies make use of surface proteins, genetic expression, and physics to isolate specific cells by phenotypic traits. Cell purification is also dependent on the cellular reagents available for use and the intended application, as these factors may preclude certain mechanisms used in the processes of labeling and sorting cells.

Overview of laser microbeam applications as related to antibody targeting

This chapter reviews several techniques which combine the use of laser microbeams with antibodies to study molecular and cellular biology. An overview of the basic properties of lasers and their integration with microscopes and computers is provided. Biophysical applications, such as fluorescence recovery after photobleaching to measure molecular mobility and fluorescence resonance energy transfer to measure molecular distances, as well as ablative applications for the selective inactivation of proteins or the selective killing of cells are described. Other techniques, such as optical trapping, that do not rely on the interaction of the laser with the targeting antibody, are also discussed.

Toward complete laser ablation of melanoma contaminant cells in a co-culture outgrowth model via image cytometry

BACKGROUND

Contaminant cancer cells in autologous transplant tissue can cause relapse and the rates are unknown. A method capable of removing all contaminant cells with a high probability detected by cytomic analyses would be useful. Neither 100% cell purging nor techniques for measuring the probability of success have been developed. Here, we report a method for removing 100% of the cells under ideal staining conditions and quantify the probability of success.

METHODS

Laser ablation was combined with previously reported automated microscopy to purge contaminant cells and evaluate 100% ablation in a co-culture model of prestained mouse melanoma cells mixed with mouse NIH-3T3 cells. Melanoma passage efficiency was measured by: (1) micropipetting single cells into microtiter wells and (2) ablating all but one melanoma cell in co-cultures.

RESULTS

(74 +/- 5)% of single melanoma cells pipetted into microtiter plate wells divided at least once. With ablation of all but one contaminant cell in co-cultures, melanoma dominated in (62 +/- 8)% cultures in 21 days. With 100% ablation in six additional experiments, no melanoma outgrowth was observed, giving a >99.1% probability that all contaminant melanoma cells were purged.

CONCLUSIONS

We successfully demonstrated a model for complete ablation within a defined probability using automated high-content image cytometry with ideal staining conditions. The results show that the instrumentation is capable of delivering 100% ablation at a defined probability and establishes the basis for further studies with clinical models wherein pretherapeutic cytomic analyses of unique cellular expression and/or morphological characteristics will be key for contaminant cancer cell identification.

High-throughput laser-mediated in situ cell purification with high purity and yield

BACKGROUND

Technologies for purification of living cells have significantly advanced basic and applied research in many settings. Nevertheless, certain challenges remain, including the robust and efficient purification (e.g., high purity, yield, and sterility) of adherent and/or fragile cells and small cell samples, efficient cell cloning, and safe purification of biohazardous cells. In addition, existing purification methods are generally open loop and exhibit an inverse relation between cell purity and yield.

METHODS

An automated closed-loop (i.e., employing feedback control) cell purification technology was developed by building upon medical laser applications and laser-based semiconductor manufacturing equipment. Laser-enabled analysis and processing has combined high-throughput in situ cell imaging with laser-mediated cell manipulation via large field-of-view optics and galvanometer steering. Laser parameters were determined for cell purification using three mechanisms (photothermal, photochemical, and photomechanical), followed by demonstration of system performance and utility.

RESULTS

Photothermal purification required approximately 10(8) W/cm(2) at 523 nm in the presence of Allura Red, resulting in immediate protein coagulation and cell necrosis. Photochemical purification required approximately 10(9) W/cm(2) at 355 nm, resulting in apoptosis induction over 4 to 24 h. Photomechanical purification required more than 10(10) W/cm(2) independent of wavelength, resulting in immediate cell lysis. Each approach resulted in high efficiency purification (>99%) after a single operation, as demonstrated with eight cell types. An automated closed-loop process to re-image and irradiate remaining targets in situ was implemented, resulting in improved purification (99.5-100%) without decreasing cell yield or affecting sterility in this closed system. Efficient purification was demonstrated with B- and T-cell mixtures over a wide range of contaminating cell percentages (0.1-99%) and cell densities (10(4)-10(6)/cm(2)). Efficient cloning of 293T cells based on fluorescence with green fluorescent protein after plasmid transfection was also demonstrated.

CONCLUSIONS

In situ laser-mediated purification was achieved with nonadherent and adherent cells on the automated laser-enabled analysis and processing platform. Closed-loop processing routinely enabled greater than 99.5% purity with a greater than 90% cell yield in sample sizes ranging from 10(1) to 10(8) cells. Throughput ranged from approximately 10(3) to 10(5) total cells/s for contaminating percentages ranging from 99% to 0.1%, respectively.

Contraction and intracellular calcium-ion elevation of cultured human aortic smooth muscle cells by endothelin-1, vasoactive intestinal contractor (VIC) and the derivatives

Effects of endothelin (ET) family peptides and their derivatives on cellular contraction and calcium-ion level were examined by using cultured human vascular smooth muscle cells (VSM). Contraction of cultured human VSM, isolated from human fetal aortic segments, was induced within 1 min after the treatment with ET-1 (100 nM) as seen in the changes of cytosolic calcium-ion localization. In parallel with the cell contraction, cytosolic calcium-ion level in the human VSM increased very rapidly and then dropped with some oscillation as determined by Anchorage Cell Analyzing System. It was noted that transient calcium-ion mobilization rather than sustained calcium-ion influx was significant in the contraction of cultured human VSM. Vasoactive intestinal contractor (VIC), three amino acids different from ET-1, had less activity in increase of intracellular calcium-ion level and in percent of response cells than ET-1, ET-2, and VIC-S4L6 (one amino acid different from ET-1). EC50 of ET-1, VIC-S4L6, ET-2, and VIC were 0.5 nM, 0.6 nM, 2.0 nM, and 20 nM, respectively. VIC-like peptide (VIC-LP), 16 amino acids fragment of VIC precursor protein, had no effect with a single administration of up to 10 microM. However, the increase in calcium-ion level by VIC was suppressed with a prior treatment of cells with high concentration (10 microM) of VIC-LP. The establishment of cultured human VSM for the simultaneous examination of the contraction and calcium-ion level will provide a new system to study signal transduction of vasocontractor peptides.

Use of scanning cytometry in studying bradykinin binding in MRC-5 cells

Ligand-receptor affinity is classically demonstrated by measuring ligand binding density to a specific site on membrane preparations, and receptor function is studied by measuring calcium flux, cell by cell, using microspectrofluorimetry. In order to study these phenomena in a large cell population, calcium flux was measured in MRC-5 cell line expressing the B2 receptor for bradykinin using an ACAS 570 scanning cytometer. Following incorporation of fluo3/AM, different ligands were studied, singly or in association with bradykinin. This study confirmed that only the B2 receptor is present on the plasma membrane of MRC-5 cells. Bradykinin binding to the B2 receptor was not modified by a B1 agonist (Des-Arg9-bradykinin) or by a B1 antagonist (Des-Arg9-[Leu8]-bradykinin) but was inhibited by a B2 agonist ([Hyp3]-bradykinin) and a B2 antagonist (HOE 140). The source of free calcium was also studied in comparison with ionomycin. The intensity of the calcium peak after binding of bradykinin is independent of the concentration of extracellular calcium. Preincubation with diltiazem or TMB-8 did not modify calcium flux, indicating that transduction of the signal after bradykinin binding in this cell line is independent of voltage-dependent channels and does not require mobilization of intracellular calcium blocked by TMB-8. In conclusion, scanning cytometry can be used to study ligand-receptor binding and to obtain results rapidly from multiple cells. Recording of individual cell variations and kinetics enables identification of active agonists or antagonists and consequently the selection of new compounds.

Scanning laser cytometry: alterations induced by cholestatic agents in isolated rat hepatocyte couplets

Scanning laser cytometry, an analytic technique that provides an accurate fluorescent measurement in adherent cells, was used to study cholestatic mechanisms in isolated rat hepatocyte couplets (IRHC). Treatment of IRHC with cholestatic compounds induced a pericanalicular F-actin accumulation and an increase in cytosolic free calcium. These data obtained with a scanning cytometer used in conjunction with an in vitro model representing the primary secretory unit suggest that abnormalities of pericanalicular F-actin filaments and calcium homeostasis play a key role in cholestasis. Considering the necessity for the development of mechanistic studies in toxicology, this technique should prove to be an outstanding tool.

Microdissection of plant chromosomes by argon-ion laser beam

Rice and barley chromosomal samples were prepared both on a polyester membrane and on an ordinary glass slide and subjected to microdissection by an argon-ion laser. The intensity and the position of the laser beam were controlled by a microcomputer. The most suitable intensity to obtain chromosomal fragments was determined experimentally. As a result, specific regions of the centromere, satellite, short arm, or long arm, of the barley and rice chromosomes were dissected out from the chromosomal spreads. Chromosomal fragments were also successfully transferred from the sample into an Eppendorf tube.

P2 purinergic receptors and cellular calcium metabolism in A 431 human epidermoid carcinoma cells

Stimulation of P2 purinergic receptors on A 431 human epidermoid cells with ATP rapidly mobilized intracellular calcium and increased cytosolic free Ca2+ ([Ca2+]i). Incorporation of 45Ca2+ was also stimulated by ATP at a rate less than that of [Ca2+]i elevation. Among a number of nucleosides, nucleotides, and their analogues examined, ATP, GTP, UTP, ADP, UDP, adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S), and 5'-adenylylimidodiphosphate (AMP-PNP) increased both [Ca2+]i and 45Ca2+ influx, whereas others did not; these latter two analogues (ATP gamma S and AMP-PNP) blocked the ATP-stimulated 45Ca2+ influx only very slightly, suggesting that they are not prominent antagonists but rather agonists. A high correlation between [Ca2+]i increase and 45Ca2+ influx, in terms of nucleotide specificity, suggests the involvement of [Ca2+]i in influx of 45Ca2+. It appeared that [Ca2+]i elevated by several nucleotides or nucleotide analogues opened a calcium gate, thus allowing the influx of 45Ca2+. P2 purinergic receptors on these cells had such a characteristic that they were rapidly desensitized. These nucleotides or analogues also affected epidermal growth factor (EGF) receptors by inhibiting the EGF binding. The differences of ligand or substrate specificities between P2 purinergic receptors and ecto-nucleotidases indicates that the two components are different molecules involved in different systems.

Interactive laser cytometric analysis of retroviral protein expression in HIV-infected lymphocytic cell lines

We have used interactive laser cytometry to investigate the expression of human immunodeficiency virus (HIV) envelope glycoproteins gp160, gp41, gp120, and the core protein p24 in the HIV-infected human lymphocyte cell lines H-9, CEM-SS, and C8166. This method allowed for the ultrasensitive detection of fluorescence signals at the single cell level and, when combined with specific anti-HIV antibodies, permitted unique quantitative detection of HIV antigens. Indirect immunofluorescence assays with monoclonal antibodies directed against gp120 revealed that a large proportion of lymphocytic cells expressed increased gp120-associated fluorescence consistent with HTLV-IIIRF infection. Certain monoclonal and polyclonal antibodies were also effective in quantifying gp160, gp41, and p24 expression. Expression of these antigens was found to vary significantly within 48 h. Significant loss (greater than or equal to 50%) of gp120 expression was observed when cells were treated with 1.0 microM AZT. The expression of the HIV-associated protein markers gp160, gp41, and p24 was detectable 24 h after infection of C8166, a cord blood lymphocytic cell line. C8166 cells expressed an additional 6- to 10-fold increase in gp120 in 48 h as well as a 3- to 4-fold increase in gp160, gp41, and p24. AZT (0.01 and 0.1 microM) decreased the expression of gp120, gp160, and p24 in a dose-dependent fashion. This new application of interactive laser cytometry permits early, sensitive, and statistically based distinctions in the expression of HIV-associated antigens in infected target cells at the single-cell level, and allows detection of important changes in HIV-associated antigen expression and the kinectics thereof.(ABSTRACT TRUNCATED AT 250 WORDS)

Culture conditions affect the cholinergic development of an isolated subpopulation of chick mesencephalic neural crest cells

Although neural crest cells are known to be very responsive to environmental cues during their development, recent evidence indicates that at least some subpopulations may be committed to a specific differentiation program prior to migration. Because the neural crest is composed of a heterogeneous mixture of cells that contributes to many vertebrate cell lineages, assessing the properties of specific subpopulations and the effect of the environment on their development has been difficult. To address this problem, we have isolated a pure subpopulation of chick mesencephalic neural crest cells by fluorescence no-flow cytometry after labeling them with monoclonal antibodies (Mabs) to a 75-kDa cell surface antigen that is associated with high affinity choline uptake. When cultures of chick mesencephalic neural crest cells are labeled with these Mabs and a fluorescent second step antibody, approximately 5% of the cells are antigen-positive (A+). After sorting, 100% of the resulting cultured mesencephalic neural crest cells are A+. The Mabs we used also label all of the neurons of the embryonic chick and quail ciliary ganglion in vivo and in vitro. We have compared the effect of various cell culture media on the isolated neural crest subpopulation and the heterogeneous chick mesencephalic neural crest from which it was derived. A+ cells were passaged and grown in a variety of media, each of which differently affected its characteristics and development. A+ cells proliferated in the presence of 15% fetal bovine serum (FBS) and high concentrations (10-15%) of chick embryo extract, but did not differentiate, although they retained basal levels of choline acetyltransferase (ChAT) activity. However, in chick serum and high (25 mM as opposed to 7 mM) K+, and heart-, iris-, or lung-conditioned medium, all of which are known to promote survival and/or cholinergic development of ciliary ganglion neurons, the cells ceased to proliferate and all of the cells in the culture became "neuron-like" within 10 days. No neuron-like cells were found in liver-, notocord-, or neural tube-conditioned media if FBS was used. When A+ cells were eliminated either by complement-mediated cytotoxicity or by laser-ablating A+ cells during no-flow cytometry, all ChAT activity was also eliminated, and no neuron-like cells or ChAT activity was found in cultures during a subsequent 3-week culture period.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunocytochemical identification and localization of the Mr 22,000 calcium-binding protein (sorcin) in an adriamycin-resistant myelogenous leukemia cell line

Monoclonal antibody against the Mr 22,000 calcium-binding protein (sorcin) from an adriamycin-resistant myelogenous leukemia cell line K562 (K562/ADM) was prepared and used as a probe to study the localization of sorcin in K562/ADM cells and the parental cell line, K562. Analysis of extracts from K562/ADM cells by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorescence image analysis showed that K562/ADM cells possessed abundant sorcin in the cytoplasm which was almost entirely absent from the drug-sensitive parental cell line, K562. Furthermore, immuno-electron microscopic studies revealed that sorcin was closely associated with free ribosomes, rough endoplasmic reticulum, mitochondria, microfilament bundles and perinuclear membranes. These observations provide the first clue that the Ca-binding protein, sorcin, may play an important role in the development of the multidrug resistance phenomenon, although the relationship between sorcin and P-glycoprotein is still unknown.

Antigen recognized by monoclonal antibodies to mesencephalic neural crest and to ciliary ganglion neurons is involved in the high affinity choline uptake mechanism in these cells

High-affinity choline uptake mechanisms are among the characteristics of cholinergic neurons such as the ciliary and choroid subpopulations in the ciliary ganglion (Barald and Berg, 1979). We have produced three monoclonal antibodies (Mabs), two of which were made to 8-day embryonic chick ciliary ganglion (CG) neurons (CG-1, CG-4) (Barald, 1982) and one of which was made to cultured mesencephalic neural crest (NC) cells (CG-14) removed from the embryo 31 hr after incubation. We have shown that all three Mabs label a common 75 kD antigen present on the cell surface of both CG neurons and NC cells (Barald, 1988). Here we report that the CG-1 and CG-4 antibodies, used in the same ratios in which they are synergistically cytotoxic for both the CG and NC cells (Barald, 1988), and Mab CG-14 alone, have specific effects on the high-affinity choline uptake mechanism (HACU) of CG neurons and isolated antigen-positive NC cells in the absence of complement. CG-1 and CG-4 in ratios of 8/1 (the same ratios that are used to kill the CG and the NC subpopulation), but neither singly, inhibit the HACU of CG neurons by 40% and that of isolated antigen-positive NC cells by 75%. However, CG-14 alone, at 1 microgram/ml, inhibits the HACU of both CG neurons and isolated NC cells by 95%. None of the antibodies had an effect on numbers of ouabain binding sites (a measure of the Na+/K+ ATPase) or cell surface acetylcholinesterase (AChE) of CG neurons or NC cells isolated by "no-flow" fluorescence cytometry with a Meridian Instruments ACAS470 cytometer. CG or NC cells grown in the presence of the antibodies without complement grow and remain healthy for many weeks. They exhibit no difference in morphology, protein content, lactate dehydrogenase activity (LDH), or division time from untreated sister cultures. Therefore, the antigen recognized by all three Mabs may be involved in a high-affinity choline uptake mechanism, a common characteristic of cholinergic neurons. The Mabs themselves may possibly label some element of the high-affinity transporter or a proximal membrane component. This implies that such a high-affinity uptake mechanism is present in the subpopulation of NC cells at early times in development. If these cells in fact are destined to contribute to the avian CG, these characteristics are present in the subpopulation before the NC cells take on a neuronal morphology.