Multi-tilt EM tomogram of primary human small airway epithelial cell (SAEC) in interphase state. The tomogram refers to the SAEC in Figure 4 of the pu...
Small airway (airway diameter , 1-2 mm) inflammation is thought to play a critical role in the pathogenesis of asthma including airways hyper-responsiveness, spontaneous exacerbations of symptoms, and tissue remodeling [3]. Non-invasive markers of inflammation, such as NO gas in the exhaled breath, could assist in the management of airway inflammation, but the anatomical source remains unclear. Our study demonstrates that small airway epithelial cells can be differentiated at an air-liquid interface to express markers such as mucin and cilia. The differentiated epithelium produces a very small, but detectable, amount of NO gas at baseline. However, the production is significantly increased, due to the upregulation of iNOS, following exposure to soluble inflammatory mediators, most notably a combination of IL-1β, TNF-α and IFN-γ. As such, iNOS in the small airway epithelium is a probable source of NO in the exhaled breath of asthma.. Bronchioles are generally , 1 mm in diameter, are devoid of ...
Primary airway epithelial cell culture provides a valuable tool for studying cell differentiation, cell-cell interactions, and the role of immune system factors in asthma
TY - JOUR. T1 - 15-deoxy-Δ-Prostaglandin J 2 induces IL-8 and GM-CSF in a human airway epithelial cell line (NCI-H 292). AU - Chiba, Takahito. AU - Ueki, Shigeharu. AU - Ito, Wataru. AU - Kato, Hikari. AU - Takeda, Masahide. AU - Kayaba, Hiroyuki. AU - Furue, Masutaka. AU - Chihara, Junichi. PY - 2009/6/1. Y1 - 2009/6/1. N2 - Background: 15-Deoxy-Δ 12,14-prostaglandin J 2 (15d-PGJ 2), a major prostanoid metabolized from prostaglandin D 2 (PGD 2), plays an important role in various biological processes including inflammatory responses. 15d-PGJ 2 exerts its effects through two major receptors, chemoattractant receptor- homologous molecule expressed on Th2 cells (CRTH2) and peroxisome proliferator-activated receptor-γ (PPARγ). The 15d-PGJ 2/PPARγ system, in particular, regulates numerous biological processes including adipogenesis, apoptosis, and inflammation. Although our studies have shown that PGD 2 (metabolic precursor of 15d-PGJ 2) induces IL-8 and GM-CSF production, the role of 15d-PGJ 2 ...
TY - JOUR. T1 - Modification of gene expression of the small airway epithelium in response to cigarette smoking. AU - Harvey, Ben Gary. AU - Heguy, Adriana. AU - Leopold, Philip L.. AU - Carolan, Brendan J.. AU - Ferris, Barbara. AU - Crystal, Ronald. PY - 2007/1/1. Y1 - 2007/1/1. N2 - The earliest morphologic evidence of changes in the airways associated with chronic cigarette smoking is in the small airways. To help understand how smoking modifies small airway structure and function, we developed a strategy using fiberoptic bronchoscopy and brushing to sample the human small airway (10th-12th order) bronchial epithelium to assess gene expression (Affymetrix HG-U133A and HG-133 Plus 2.0 array) in phenotypically normal smokers (n = 16, 25 ± 7 pack-years) compared to matched nonsmokers (n = 17). Compared to samples from large (second to third order) bronchi, the small airway samples had a higher proportion of ciliated cells, but less basal, undifferentiated, and secretory cells, and contained ...
Culturing of respiratory viruses in well-differentiated pseudostratified human airway epithelium as a tool to detect unknown viruses ...
... By David Proud * Publisher: Wiley * Number Of Pages: 460 * Publication Date: 2008-06-03 * ISBN-10 /
Specialty Areas: Normal Physiology of Airway Surface Liquids (ASL); ASL System Failure in CF and COPD. Research Focus:. Dr. Bouchers lab has focused on the normal physiology of airway surface liquids (ASL) and how this system fails in airways diseases, e.g., cystic fibrosis and COPD. The lab pursues a variety of investigations into the functions of airway epithelia in health and disease. In general terms, the lab focuses on five interrelated areas of research:. ...
Approaches to drug screening typically involve dramatic compromises in order to achieve high throughput and hold down costs. Examples include the use of immorta...
Inhibition of Toll-Like Receptor 2-Mediated Interleukin-8 Production in Cystic Fibrosis Airway Epithelial Cells via the α7-Nicotinic Acetylcholine Receptor
BACKGROUND: The ability to transform normal human cells into cancer cells with the introduction of defined genetic alterations is a valuable method for understanding the mechanisms of oncogenesis. Easy establishment of immortalized but non-transformed human cells from various tissues would facilitate these genetic analyses. RESULTS: We report here a simple, one-step immortalization method that involves retroviral vector mediated co-expression of the human telomerase protein and a shRNA targeting the CDKN2A gene locus. We demonstrate that this method could successfully immortalize human small airway epithelial cells while maintaining their chromosomal stability. We further showed that these cells retain p53 activity and can be transformed by the KRAS oncogene. CONCLUSIONS: Our method simplifies the immortalization process and is broadly applicable for establishing immortalized epithelial cell lines from primary human tissues for cancer research.
Nipah virus (NiV) is a zoonotic emerging pathogen that can cause severe and often fatal respiratory disease in humans. The pathogenesis of NiV infection of the human respiratory tract remains unknown. Reactive oxygen species (ROS) produced by airway epithelial cells in response to viral infections contribute to lung injury by inducing inflammation and oxidative stress; however, the role of ROS in NiV-induced respiratory disease is unknown. To investigate whether NiV induces oxidative stress in human respiratory epithelial cells, we used oxidative stress markers and monitored antioxidant gene expression. We also used ROS scavengers to assess their role in immune response modulation. Oxidative stress was confirmed in infected cells and correlated with the reduction in antioxidant enzyme gene expression. Infected cells treated by ROS scavengers resulted in a significant decrease of the (F2)-8-isoprostane marker, inflammatory responses and virus replication. In conclusion, ROS are induced during NiV
TY - JOUR. T1 - SUV39H1 reduction is implicated in abnormal inflammation in COPD. AU - Chen, Tzu Tao. AU - Wu, Sheng Ming. AU - Ho, Shu Chuan. AU - Chuang, Hsiao Chi. AU - Liu, Chien Ying. AU - Chan, Yao Fei. AU - Kuo, Lu Wei. AU - Feng, Po Hao. AU - Liu, Wen Te. AU - Chen, Kuan Yuan. AU - Hsiao, Ta Chih. AU - Juang, Jer Nan. AU - Lee, Kang Yun. PY - 2017/1/1. Y1 - 2017/1/1. N2 - Chronic obstructive pulmonary disease (COPD) is characterized by enhanced chronic inflammation in the airways, lung parenchyma, and circulation. We investigated whether SUV39H1, a histone methyltransferase, is causatively implicated in the abnormal inflammation observed in COPD. The SUV39H1 and H3K9me3 levels were reduced in peripheral blood mononuclear cells (PBMCs), primary human small airway epithelial cells (HSAEpCs) and lung tissues from COPD patients, which were correlated with poor lung function and the serum IL-8 and IL-6 levels. A specific SUV39H1 inhibitor, chaetocin, induced a distinct COPD panel of ...
Increased mucus production is a common cause of morbidity and mortality in inflammatory airway diseases, including asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis. However, the precise molecular mechanisms for pathogenic mucus production are largely undetermined. Accordingly, there are no specific and effective anti-mucus therapeutics. Here, we define a signaling pathway from chloride channel calcium-activated 1 (CLCA1) to MAPK13 that is responsible for IL-13-driven mucus production in human airway epithelial cells. The same pathway was also highly activated in the lungs of humans with excess mucus production due to COPD. We further validated the pathway by using structure-based drug design to develop a series of novel MAPK13 inhibitors with nanomolar potency that effectively reduced mucus production in human airway epithelial cells. These results uncover and validate a new pathway for regulating mucus production as well as a corresponding therapeutic approach to mucus ...
Activation of transcription factor IL-6 (NF-IL-6) and nuclear factor-kappaB (NF-kappaB) by lipid ozonation products is crucial to interleukin-8 gene expression in human airway epithelial cells. Ozone (O(3)) is a major component of smog and an inhaled toxicant to the lung. O(3) rapidly reacts with the airway epithelial cell membrane phospholipids to... ...
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Li, J., Patterson, M., Chew, W. L., Cho, S-H., Gilmour, I., Oliver, T., ... Liedtke, W. (2011). TRPV4-Mediated calcium-influx into human bronchial epithelia upon exposure to diesel exhaust particles. Environmental Health Perspectives, 119(6), 784 - 793. ...
TY - JOUR. T1 - Effect of cytokines on ICAM-1 and ZO-1 expression on human airway epithelial cells. AU - Shahana, Shahida. PY - 2005/9. Y1 - 2005/9. N2 - The presence of adhesion molecules on airway epithelial cells may be important in recruiting leukocytes to the epithelium. The study aimed at investigating the effects of interleukin (IL)-4, IL-8, IL-13 and interferon-gamma (IFN-gamma) on cell viability and intracellular adhesion molecule (ICAM)-1 and zonula occludens protein (ZO)-1 expression on cultured human basal and columnar airway epithelial cells. Cycloheximide (CHX) induced cell death in both cell lines. The cytokines IL-4, IL-8, IL-13 and IFN-gamma had only minor effects on cell proliferation in the columnar 16HBE14o-cells, and inhibited the effects of CHX on cell death. IFN-gamma increased ICAM-1 expression in both cell lines. Western blot analysis showed that CHX inhibited both ICAM-1 and ZO-1 expression in the basal cell line. A combination of IL-4 and IFN-gamma appeared to break ...
Free Online Library: Phosphorylation of p53 protein in A549 human pulmonary epithelial cells exposed to asbestos fibers. (Research). by Environmental Health Perspectives; Health, general Environmental issues
Goal of the present study is to investigate the specific cellular responses to nCeO2 and nFe2O3 in various lung cell types and develop an in vitro chronic exposure model to predict the potential fibrogenic and carcinogenic effects. Primary human lung fibroblasts were treated with nCeO2 (size dXRD = 17 nm, SSA = 61 m2/g) and direct stimulation of collagen production (a hallmark of fibrosis) was evaluated. In separate experiments, primary human small airway epithelial cells were exposed to a sub-lethal concentration (0.625 µg/cm2) of nCeO2 and nFe2O3 (size dXRD = 20 nm, SSA = 50 m2/g) for 6 weeks and their effects on cell transformation and invasion were evaluated. Our results showed new data that nCeO2 can induce a dose-dependent increase in collagen production by lung fibroblasts; nCeO2 can induce proliferation of lung epithelial cells as compared to vehicle-treated control and nFe2O3 induced neoplastic transformation of epithelial cells as determined by soft-agar colony formation assay and transwell
Lin, H., Li, H., Cho, H.-J., Bian, S., Roh, H.-J., Lee, M.-K., Kim, J. S., Chung, S.-J., Shim, C.-K. and Kim, D.-D. (2007), Air-liquid interface (ALI) culture of human bronchial epithelial cell monolayers as an in vitro model for airway drug transport studies. J. Pharm. Sci., 96: 341-350. doi: 10.1002/jps.20803 ...
3896 Purpose: To evaluate the oncogenic impact of p53 knockdown, mutant K-RASV12, mutant EGFR alone and their combination on tumorigenicity of a newly developed immortalized human bronchial epithelial cell line. Background: Molecular analysis of lung cancer has revealed several genetic and epigenetic alterations in the multistep pathogenesis of lung cancer. However, little is known about the relative importance of each individual alteration on the tumorigenic process. One approach is to use a model system in which the contribution of each genetic alteration to lung tumorigenesis can be assessed individually and combinatorially. We have developed an in vitro model system using normal human bronchial epithelial cells that overexpress Cyclin-dependent kinase 4 and human telomerase. Ectopic expression of these two genes enables the cells to bypass the growth inhibitory signals of the p16/Rb pathway and also replicative senescence induced by shortened telomeres. We manipulated this cell line (HBEC3), ...
Act1/CIKS is an intracellular protein that has been shown to play an important role in mediating IL-17A and IL-25 signaling effects. Recently, defects in Act1 function and/or expression has been implicated in inflammatory disease, such as psoriatic arthritis and atopic dermatitis. We have found that the modulation of Act1 expression levels in human airway epithelial cells changes the expression levels of some genes, in the absence of cytokine stimulation. RNAseq is a powerful new technique to quantitatively measure changes at the transcriptome level. Here we describe the use of RNAseq to globally analyze the effects of modulating Act1 expression in human airway epithelial cells. ...
In our study we demonstrate that the plasma levels of UTP are significantly elevated in patients with acute myocardial infarction. A combination of pharmacology and mRNA quantification indicates that UTP is probably acting via P2Y2 receptors in man, and via both P2Y2 and P2Y4 receptors on cardiomyocytes from mice. Our results indicate that UDP is a novel inotropic factor acting via P2Y6 receptors.. The first demonstration of UTP release used [3H]uridine-labeled endothelial cells. In the study, [3H]UTP release occurred in response to increased flow.27 Since the development of the first sensitive quantitative assay for UTP, its release has been measured from a variety of cells including platelets, leukocytes, primary airway epithelial cells, rat astrocytes, and several other cell lines.24 To our knowledge, we are now the first to quantify UTP levels in human plasma. UTP levels correlated significantly with ATP, indicating corelease of the nucleotides. The UTP levels were ≈1:10 of the ATP levels, ...
The airway epithelial cell core provides investigators with primary culture preparations of human and mouse airway epithelial cells. We routinely procure human tissues from lung transplantation donors and explanted lungs and surgical tissues, including those with lung disease. The core can also culture airway cells obtained by lung and nasal brushing or scraping. In collaboration with core users, Brody Lab members will establish cultures from mice or materials provided by the core users. Core users can be instructed on all methods for culture, manipulation and evaluation of preparations. Lead time of one month should be provided to allow for scheduling and the necessary period for cell growth. IRB permission may be required for some tissues and studies.. ...
Lung cancer is the most common cause of cancer-related deaths. Tobacco smoke exposure is the strongest aetiological factor associated with lung cancer. In this study, using serial analysis of gene expression (SAGE), we comprehensively examined the effect of active smoking by comparing the transcriptomes of clinical specimens obtained from current, former and never smokers, and identified genes showing both reversible and irreversible expression changes upon smoking cessation. Twenty-four SAGE profiles of the bronchial epithelium of eight current, twelve former and four never smokers were generated and analyzed. In total, 3,111,471 SAGE tags representing over 110 thousand potentially unique transcripts were generated, comprising the largest human SAGE study to date. We identified 1,733 constitutively expressed genes in current, former and never smoker transcriptomes. We have also identified both reversible and irreversible gene expression changes upon cessation of smoking; reversible changes were
Objective: Excessive airway inflammation is seen in chronic obstructive pulmonary disease (COPD) patients experiencing acute exacerbations, which are ..
NL20 (ATCC CRL-2503) is an immortalized, nontumorigenic human bronchial epithelial cell line derived from normal bronchus taken from an accident victim at autopsy. The cell line was established by transfection with the origin of replication-defective SV40 large T plasmid, p129.
NL20 (ATCC CRL-2503) is an immortalized, nontumorigenic human bronchial epithelial cell line derived from normal bronchus taken from an accident victim at autopsy. The cell line was established by transfection with the origin of replication-defective SV40 large T plasmid, p129. NL20 cells at passage 183 were inoculated into nude mice and a small slowly growing subcutaneous tumor developed from a minor clone in this otherwise stable cell line.
Sigma-Aldrich offers abstracts and full-text articles by [Phillip A Wages, Robert Silbajoris, Adam Speen, Luisa Brighton, Andres Henriquez, Haiyan Tong, Philip A Bromberg, Steven O Simmons, James M Samet].
Bronchial epithelium. Coloured scanning electron micrograph (SEM) of a cultured bronchial epithelial cell. The respiratory epithelium is composed of a mixed population of ciliated, nonciliated, and mucous-secreting cells from proximal to distal airways. In vitro models ( cell culture) using primary cells and cell lines are essential for understanding the function and pathophysiology of these cells in diseases such as asthma. Magnification: x 2000 when printed 10 centimetres wide. - Stock Image C022/6437
As part of a robust innate immune system, the cells of the airway epithelium secrete fluid and proteins to create the highly proteinaceous periciliary liquid (PCL). Many proteins present in the PCL have proposed antimicrobial functions, including two of the most abundant proteins, BPIFA1 (SPLUNC1) and BPIFB1 (LPLUNC1). The function of these two proteins in host defence is unresolved and we hypothesize that they interact with the respiratory pathogen, S. aureus, to limit infection.. Air-liquid interface (ALI) cultures of primary bronchial epithelial cells secrete many proteins present in the PCL, including BPIFA1 and BPIFB1. Pull down assays interacting cell secretions with S. aureus were used to visualise protein-bacterial interactions. Both BPIFA1 and BPIFB1 were shown interact strongly with S. aureus. Recombinant proteins generated in CHO cells exhibited similar binding to the endogenous proteins. Deglycosylation using PNGase F treatment prior to pull down assays highlighted that these ...
My research interests are to elucidate the cellular and molecular mechanisms by which environmental carcinogens cause lung cancer and to identify markers for the diagnosis, prognosis and treatment of this disease. We investigate genetic and epigenetic changes in oncogenes and tumor suppressor genes in specimens obtained from lung cancer patients and individuals at high risk for developing lung cancer. In addition, we apply new mouse models to investigate pathways of tobacco smoke carcinogen-mediated lung tumorigenesis. We would like to understand how airway epithelial cells are involved in the initiation and progression of lung tumors, and how they are influenced by environmental factors that increase lung cancer risk and how they respond to therapies. ...
See the Supplemental Methods for more details.. Primary culture of human airway epithelial cells. hTECs were isolated by enzymatic digestion, seeded onto permeable filter supports, and grown as described previously (6). For the present experiments, cells were cultured in DMEM-Hams F12 medium with 2% NuSerum (BD), Primocin (100 μg/ml, InvivoGen), and retinoic acid (1 × 10-8 M, Sigma-Aldrich) with or without IL-13 (50 ng/ml, Peprotech) under submerged conditions for 2 days and then air-liquid interface conditions for 3 weeks. Cells were also cultured in the presence or absence of inhibitors that were added 1 day before addition of IL-13 and were readded with each IL-13 treatment (twice per week). Transepithelial electrical resistance of cell cultures was monitored as described previously (63). Real-time qPCR assay. Target mRNA levels were quantified with real-time qPCR using fluorogenic probe/primer combinations specific for CLCA1, CLCA2, CLCA4, MUC5AC, MAPK13, MAPK14, and GAPDH (Supplemental ...
1) The main issue with this paper is this: these cell lines, although originally human, are all immortalized cancer cell lines characterised by markedly different biological properties when compared to normal human cells of the same tissue/cell type. They cant be readily used a surrogates for normal human tissue/cell types. None were primary cells nor were any even from recently acquired tissue samples from biopsies etc. People have infected primary human airway epithelial cultures with hCoV-EMC - so this can be done successfully - , although it would be more difficult for other tissue types as these cultures havent been developed. Some of these cell lines used may by chance lack key viral repressors of infection present in normal primary cells, which could skew results from cell culture infection experiments. Plus, a human tissue is not just a single cell type - they are composed of diverse kinds of cells that could together behave much, much differently than cell lines in culture ...
Incidence of acute asthma, defined as the number of persons who develop asthma within a specific time period, is approximately % annually. Childhood asthma persists into adulthood in approximately 50% of cases. Those with symptoms persisting into the second decade of life usually have asthma throughout adulthood. Asthma prevalence is 6-10% (ie, million persons); one half of these cases are children (ie, 8-20% of all children). Overall, acute asthma represents about 2% of all ED visits Childhood asthma
Hackett, T.L., Shaheen, F., Johnson, A., Wadsworth, S., Pechkovsky, D.V., Jacoby, D.B., et al. (2008) Characterization of side population cells from human airway epithelium. Stem Cells, 26, 2576-2585.doi10.1634/stemcells.2008-0171
Bronchial Epithelial Cell Medium-basal https://www.sciencepro.com.br/produtos/sc-3211-b https://www.sciencepro.com.br/@@site-logo/logo-novo.png ...
Explore the science and understand more clearly the Alveolar Epithelium topic by reading the best articles made from Experts, Scientific and Academics!
Mycobacteria are antibiotic-resistant microbes that are often implicated in lung infections. To fight them, the body activates interferon and other immune proteins, but scientists werent sure how the process worked
A new collaborative study describes a way that lung tissue can regenerate after injury. The team found that lung tissue has more dexterity in repairing tis | Genetics And Genomics
RT-PCR for IL-8 (A), IL-6 (B), HOX1 (C), and COX2 (D) relative to GAPDH in unexposed NHBE cells. RNA for all proteins significantly changed with differentiation
K+ channels are expressed in a wide variety of cell types, including airway epithelial cells. The purpose of this study was to investigate the role of various Kv and KCa channels in cell proliferation and cell volume ...
The respiratory epithelium is lined by a tightly balanced fluid layer that allows normal O-2 and CO2 exchange and maintains surface tension and host defense ...
Cystic fibrosis (CF) is a multi-organ autosomal recessive disease of fluid-transporting epithelia, due to a mutation in the gene coding for the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR is a cAMP-regulated Cl-channel involved in various regulatory processes. Salt and water transport depend on CFTR and the epithelial sodium channel (ENaC), operating in concert with the paracellular pathway through the tight junctions (TJ). The ionic composition of the ASL has been assumed to be altered in CF, resulting in a fatal accumulation of viscous mucus in the airways.. ASL samples were collected from tracheal and nasal fluid in normal and transgenic CF mice and from the fluid covering the apical surface of normal bronchial cells (16HBE14o-) and a CF human bronchial cell line (CFBE41o-). Analysis of the elemental content of the ASL was performed by X-ray microanalysis. The ASL contained more Na and Cl in CFTR-deficient or DF508-CFTR-containing cells than in control cells with ...
During the course of this project, we witnessed the emergence of the Middle East Respiratory Syndrome Coronavirus (MERS-CoV). MERS-CoV is associated with severe respiratory disease and has an exceptionally high case fatality of approximately 40%. Initially, it was not known either how efficiently the MERS-CoV could replicate on the human airway epithelium or whether any measures were available to inhibit MERS-CoV replication in the human airway epithelium, indeed, even the nature of the target cell(s) was unknown. Since primary HAE-cultures were immediately at our command, we could participate in a number of international studies. We were the first to demonstrate that MERS-CoV can efficiently replicate on the primary human epithelium, which highlights its zoonotic potential (2).. Importantly, the treatment of MERS-CoV-infected HAE-cultures with interferon-alpha and interferon-lambda significantly reduced viral replication. Hence, this strategy opens up a therapeutic option for MERS-CoV patients ...
In this article, we provide an overview of the experimental workflow by the Lung and Particle Research Group at Cardiff University, that led to the development of the two in vitro lung models - the normal human bronchial epithelium (NHBE) model and the lung-liver model, Metabo-Lung™. This work was jointly awarded the 2013 Lush Science Prize. The NHBE model is a three-dimensional, in vitro, human tissue-based model of the normal human bronchial epithelium, and Metabo-Lung involves the co-culture of the NHBE model with primary human hepatocytes, thus permitting the biotransformation of inhaled toxicants in an in vivo-like manner. Both models can be used as alternative test systems that could replace the use of animals in research and development for safety and toxicity testing in a variety of industries (e.g. the pharmaceutical, environmental, cosmetics, and food industries). Metabo-Lung itself is a unique tool for the in vitro detection of toxins produced by reactive metabolites. This 21st ...
An increasing number of studies using primary human bronchial epithelial cells (BECs) have reported intrinsic differences in the expression of several genes between cells from asthmatic and non-asthmatic donors. The stability of gene expression by primary BECs with increasing cell passage number has not been well characterized. To determine if expression by primary BECs from asthmatic and non-asthmatic children of selected genes associated with airway remodeling, innate immune response, immunomodulatory factors, and markers of differentiated airway epithelium, are stable over increasing cell passage number, we studied gene expression patterns in passages 1, 2, 3, 4, and 5 BECs from asthmatic (n = 6) and healthy (n = 6) subjects that were differentiated at an air-liquid interface. RNA was harvested from BECs and RT-PCR was performed for TGFβ1, TGFβ2, activin A, FSTL3, MUC5AC, TSLP, IL-33, CXCL10, IFIH1, p63, KT5, TUBB4A, TJP1, OCLN, and FOXJ1. Expression of TGFβ1, TGFβ2, activin A, FSTL3, MUC5AC,
Human tracheobronchial epithelial cells have been serially passaged in serum-free medium. This serum-free model was employed to investigate the effects of different concentrations of Ca2+ (0.1, 1.0 and 2.0 mM) on multiplication and morphology of the cells. The responses were analysed in terms of growth kinetics, histochemical and ultrastructural alterations. Culturing of the cells in high Ca2+ (1.0-2.0 mM) medium stimulated cell multiplication characterized by increased colony forming efficiency, greater number of cells per colony and cell population doublings per day. Additionally, the high Ca2+ concentrations induced proliferation in cultures grown to confluency in low Ca2+ (0.1 mM) medium. Cells propagated in low Ca2+ medium consisted of relatively heterogeneous cell populations, with most cells staining positive with periodic acid-Schiff (PAS) reagent. Ultrastructurally the cells exhibited secretory vesicles and microvilli on their surfaces, small desmosomes and intercellular interdigitation ...