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PubMed1980

Differentiation and function of rat adipocyte precursor cells in primary culture.

Precursor cells to adipocytes were purified from the epididymal fat pads of small rats and studied in primary culture. A culture system in which substrate and cofactors were not rate-limiting for complete adipocyte conversion was used by utilizing an agarose feeding-layer. Detachment of cells from the culture dish was prevented by addition of a viscous layer of culture medium, containing methyl cellulose. This system allowed quantitation and definite characterization of formed adipocytes, defined as cells accumulating a lipid droplet >20 micro m in diameter. The cells could be subcultured but then gradually lost their adipocyte conversion ability. Age of the donor depressed the adipocyte conversion which, however, never seemed to stop completely. Prostaglandin E(1) and F(2alpha) had no definite effect in the physiological concentration range while indomethachin possibly had a weak inhibitory effect. Insulin, heparin, and isobutylmethylxanthine increased adipocyte formation. Development of characteristic adipocyte functions with time was examined. Lipoprotein lipase activity was very low in the isolated precursor cells before culture, but developed in culture at confluence and was a thousand-fold higher within a few days. At this peak lipoprotein lipase activity was 50-fold higher than in mature adipocytes from the same donor animal. Triglyceride synthesis from glucose peaked in parallel but never reached the value of mature adipocytes and very little fatty acid was synthesized. Hormone-sensitive glycerol release developed at confluence and reached the level of activity of mature adipocytes. This study and previous work have indicated a role for the cyclase system in the development of adipocytes from precursor cells. Dibutyrylcyclic AMP caused an enhancement of lipoprotein lipase activity and adipocyte conversion. In suspension media, the nucleotide caused inhibition. These results are compatible with an effect of the nucleotide, not directly on lipoprotein lipase and cell determination, but via events taking place at confluence associated with cell to cell interactions. In comparison with previously described cells from an established cell line which undergo adipose conversion (3T3 cells), the cells described in the present work, like adipocytes, showed more metabolic activity in pathways for fatty acid incorporation from exogenous lipid sources (lipoprotein lipase activity) than from de novo synthesis. Furthermore, host-factors could be followed such as in the age- and site-dependence of adipocyte formation. Physiological stimuli such as insulin, lipid substrate, and heparin had effects on adipocyte formation. It was therefore concluded that this cell preparation has a potential of yielding information of physiological significance in studies of the regulation of adipocyte multiplication.-Björntorp, P., M. Karlsson, P. Pettersson, and G. Sypniewska. Differentiation and function of rat adipocyte precursor cells in primary culture.

Adipose Tissue↗
PubMed2006

Assessing normative cut points through differential item functioning analysis: an example from the adaptation of the Middlesex Elderly Assessment of Mental State (MEAMS) for use as a cognitive screening test in Turkey.

BACKGROUND: The Middlesex Elderly Assessment of Mental State (MEAMS) was developed as a screening test to detect cognitive impairment in the elderly. It includes 12 subtests, each having a 'pass score'. A series of tasks were undertaken to adapt the measure for use in the adult population in Turkey and to determine the validity of existing cut points for passing subtests, given the wide range of educational level in the Turkish population. This study focuses on identifying and validating the scoring system of the MEAMS for Turkish adult population. METHODS: After the translation procedure, 350 normal subjects and 158 acquired brain injury patients were assessed by the Turkish version of MEAMS. Initially, appropriate pass scores for the normal population were determined through ANOVA post-hoc tests according to age, gender and education. Rasch analysis was then used to test the internal construct validity of the scale and the validity of the cut points for pass scores on the pooled data by using Differential Item Functioning (DIF) analysis within the framework of the Rasch model. RESULTS: Data with the initially modified pass scores were analyzed. DIF was found for certain subtests by age and education, but not for gender. Following this, pass scores were further adjusted and data re-fitted to the model. All subtests were found to fit the Rasch model (mean item fit 0.184, SD 0.319; person fit -0.224, SD 0.557) and DIF was then found to be absent. Thus the final pass scores for all subtests were determined. CONCLUSION: The MEAMS offers a valid assessment of cognitive state for the adult Turkish population, and the revised cut points accommodate for age and education. Further studies are required to ascertain the validity in different diagnostic groups.

Adolescent↗
PubMed2004

Recent mammalian gene duplications: robust search for functionally divergent gene pairs.

Comparison of 317 gene pairs in human and mouse that were duplicated after the most recent common ancestor of the two species was used to search for candidates that may have undergone functional differentiation. Even when corrected for multiple tests, Tajima's relative rate test showed significant rate differences in 36% of cases for which the test was applicable. However, a significant result in this case was increasingly likely as the sequence length increased; thus, a statistically significant result of a relative rate test may not be biologically meaningful. We used regression methods to provide more robust methods of testing for functionally differentiated gene pairs, which take into account the variation in the entire data set by examination of residuals from regression-identified gene pairs with unusually high nonsynonymous divergence from a reference sequence and from each other. This approach identified six duplicate gene pairs that appeared to be candidates for functional differentiation as a result of positive Darwinian selection.

Amino Acid Sequence↗
PubMed1988

[Enzymes of the Xenobiotic Metabolism of Continuous Cell Lines in invitro Toxicity Testing]

Cells in continuous culture contain a large number of enzymes which are involved in the metabolism of potentially toxic chemicals. As a rule, the activities of these enzymes represent functions of low tussle specificity. In contrast, those functions which are specialized "differentiated" functions in vivo are no longer expressed in continuous cell lines. However, an increasing number of observations indicates that cell lines may also contain these functions. Cell lines which lack or possess specific xenobiotic metabolizing enzymes are already applicable for analyzing the complex mechanisms of activation and inactivation of chemicals. With a better understanding how differentiated cell functions are regulated, prospects are promising for establishing metabolically competent cell lines, which can also be used in the screening of toxic chemicals.

Journal Article↗
PubMed1977

Differentiation of functionally active mouse T lymphocytes from functionally inactive bone marrow precursors II. Limited recovery of T-cell responses from mouse bone marrow in tissue culture.

The limited differentiation of mature T cell function from mouse bone marrow in tissue culture is described and compared with similar differentiation occuring in vivo in irradiated bone marrow protected mice. Data are presented to show that a pool of precursors, similar in size to that able to produce early (transient?) regeneration in thymectomized recipients, is responsible for the development of mitogen responsive T cells active in MLC (proliferation) and CML (development of cytotoxic cells) assays. In contrast, a helper cell population which augments antibody formation from T-depleted normal spleen cells derives from a pool of similar precursors yet does not seem to be theta positive. Similarly, larger cells (perhaps typical of those giving rise to suppressor T cells in vivo) give rise to a suppressor cell pool after 4 days of culture, though again only a fraction of this suppressor activity could be attributed to theta positive cells. It is suggested that much of the data for regenration of T lymphocytes in vitro from T-depleted sources needs to be re-interpreted in terms of this evidence for a pool of post-thymic precursors of T cells in such T-deficient cell populations.

Animals↗
PubMed1999

The effects of lysophosphatidate on thyrotropin-mediated differentiated thyroid function in FRTL-5 thyroid cells.

Lysophosphatidate (LPA; 1-acyl-sn-glycero-3-phosphate) is a novel lipid mediator with diverse biological activity. The intracellular mechanisms that mediate the actions of LPA include activation of phospholipase C and protein kinase C (PKC), increases in intracellular Ca2+, inhibition of adenylyl cyclase, and activation of phospholipase D (PLD). We have shown that thyrotropin (TSH) mediated PLD activation involves both the cyclic adenosine monophosphate (cAMP) and PKC pathways. We determined the effects of LPA (10 or 50 microM; 30 minutes) on TSH- and forskolin-mediated cAMP production in FRTL-5 thyroid cells. Basal cAMP was unaffected by LPA. However, both 10 microM and 50 microM LPA inhibited TSH-mediated cAMP production by 66% and 64%, respectively (p < 0.01, ANOVA). A similar inhibition of forskolin-mediated cAMP production was observed following LPA (p < 0.01, ANOVA). After 30-minutes exposure to 50 microM LPA, TSH-mediated iodide uptake (IU) was unaffected. However, 50 microM LPA enhanced TSH-IU after 24-hour exposure by 23%+/-8% (p < 0.03, ANOVA) and inhibited TSH-IU following 72-hour exposure by 43%+/-10% (p < 0.02, ANOVA). There was no effect of LPA on basal IU. To determine whether PLD activation mediated the effects of LPA, PLD activity was examined in FRTL-5 thyroid cells 30 minutes after LPA exposure. While PLD was increased 3.5-fold compared to control values following 50 microM LPA (p < 0.05, ANOVA), no increase in PLD activation was seen following treatment with 10 microM LPA. Preliminary evidence revealed no effect of a protein kinase C inhibitor on LPA inhibition of cAMP generation. To examine the products of PLD activation, we measured the production of phosphatidate (PA) and diacylglycerol (DAG) in FRTL-5 thyroid cells following treatment with 50 microM LPA or 100 microU/mL TSH. Within 1 minute following LPA, a rapid spike of DAG production was observed (1.5- +/- 0.2-fold above basal, p < 0.05, ANOVA). No similar increases in PA or bisPA were demonstrated. However, TSH caused a steady increase in PA and DAG that reached a maximum after 30 minutes. In summary, the effects of LPA on differentiated thyroid function in FRTL-5 thyroid cells are complex. LPA inhibits TSH- and forskolin-mediated cAMP generation most likely via a direct inhibition of adenylyl cyclase, whereas its effects on TSH-IU involve other mechanisms, possibly including PLD activation.

Animals↗
PubMed1979

Differentiation of functionally active mouse T lymphocytes from functionally inactive bone marrow precursors. III. Induction of T-cell activities by growth of bone marrow on feeder layers prepared from mouse thymocytes.

The ability of small and large T precursor cell pools to differentiate into mature functional T lymphocytes on thymus feeder cell layers or in the presence of a supernatant prepared from such feeder layers was compared. Evidence was obtained showing that the small cell pool differentiated as effectively in the presence of soluble factors prepared from the thymus cultures as in the presence of the thymus cells themselves. In contrast, large stem cells apparently needed cellular contact with the thymus feeder cultures in order to promote differentiation, though a time point could be found at which further differentiation from this precursor pool would also occur in the presence of the thymus culture supernatant only. These data concurred with evidence from in vivo experiments for two pools of T-cell precursors which differentiated in thymectomized or thymus-intact recipients respectively.

Animals↗
PubMed1998

The captopril renogram: a new tool for diagnosing and predicting obstruction in childhood hydronephrosis.

PURPOSE: We evaluated the difference in response patterns of captopril versus standard renography for assessing hydronephrosis due to suspected ureteropelvic and ureterovesical junction obstruction. This technique may identify hydronephrotic kidneys in which normal function is maintained by vasoactive compensatory mechanisms. Sustained obstruction may cause these mechanisms to fail, and expose the kidneys to permanent functional deterioration in the long term. MATERIAL AND METHODS: We prospectively studied 15 boys and 8 girls with a mean age of 3.5 years with grades III to IV/IV hydronephrosis. Evaluations included renal sonography, standard diuretic and captopril renography, glomerular filtration rate, voiding cystography, serum creatinine, blood pressure, and urinalysis with culture and sensitivity. Obstruction was suspected at the ureteropelvic junction in 19 kidneys and at the ureterovesical junction in 9. We compared differential function values obtained by standard diuretic and captopril renography. RESULTS: We observed certain patterns in response to captopril renography, including pattern 1--unilateral decrease in hydronephrotic kidney relative function in 5 of 23 cases, 2--bilateral decreased function in 2, 3--bilateral increased function in 4 and 4--no change in function in 12 on standard renography. When half-time was more than 20 minutes on standard diuretic renography in 8 cases, captopril renography showed an ipsilateral decrease and bilateral increase in glomerular filtration rate in 4 and 1, respectively, and no change in 3. In 12 of the 23 patients (52%) there was no difference in the results of captopril and diuretic renography as well as no change in differential function on standard diuretic renography during 1 1/2 years of observation. Surgical correction was performed in 4 patients in whom half-time was greater than 20 minutes and differential function was decreased on captopril renography. CONCLUSIONS: Our preliminary study reveals that there may be a role for captopril renography for detecting renin-angiotensin system mediated compensatory mechanisms in obstructive uropathy. When such compensatory mechanisms are activated, they may be unmasked by captopril, producing 1 of 4 patterns on renography and glomerular filtration rate. Patterns may indicate different degrees of impending renal function impairment and, thus, they may become useful for determining the progression of injury, when present, and the appropriate timing of surgical intervention.

Captopril↗
PubMed2001

In vitro effects of environmental salinity and cortisol on chloride cell differentiation in embryos of Mozambique tilapia, Oreochromis mossambicus, measured using a newly developed 'yolk-ball' incubation system.

To examine the functional differentiation of chloride cells in the yolk-sac membrane of tilapia (Oreochromis mossambicus) embryos, we developed a 'yolk-ball' incubation system in which the yolk sac was separated from the embryonic body and subjected to incubation in vitro. The yolk-ball preparation consists of the yolk and the covering yolk-sac membrane, which contains a rich population of chloride cells. After appropriate cutting, the incision on the yolk ball healed during incubation in balanced salt solution for 3h, so that the yolk-sac membrane completely enclosed the yolk. Yolk balls prepared from freshwater-acclimated embryos were transferred either to fresh water or to sea water and incubated for 48 and 96 h to elucidate the morphological changes in the chloride cells in response to environmental salinity. The chloride cells in the yolk-sac membrane were larger in sea water than in fresh water. In yolk balls transferred to sea water, chloride cells often formed multicellular complexes characteristic of seawater-type chloride cells. In those transferred to fresh water, however, the cells were small and rarely formed such complexes. These responses of chloride cells were identical to those observed in intact embryos. Thus, chloride cells in the yolk-sac membrane could differentiate into the seawater type independent of the embryonic body. To examine the possible effects of exogenous cortisol on chloride cell differentiation, the yolk balls were incubated for 48 h in fresh water or sea water containing different doses of cortisol (0.1-10 microg x ml(-1)). Although chloride cells were consistently larger in sea water than in fresh water in all experimental groups, cortisol administration had no effect on chloride cell surface area in either medium. These findings indicate that the chloride cells in the yolk-sac membrane are equipped with an autonomous mechanism of functional differentiation that is independent of the embryonic endocrine and nervous systems. The yolk-ball incubation system established here is an excellent experimental model for further studies on chloride cell differentiation and function.

Animals↗
PubMed1987

Differentiated transport functions in primary cultures of rabbit collecting ducts.

Fragments of rabbit cortical collecting tubule (CCT) were isolated by solid-phase immunoadsorption with a monoclonal antibody against an ectoantigen on principal cells. Primary cultures, initiated from the "immunodissected" cells, were then grown to confluency in porous bottom dishes. The purity of the freshly isolated and cultured cells was verified by flow cytometry and immunocytochemistry, using a panel of cell-specific monoclonal antibodies and lectins. As a result of continued vectorial transport, the cultured epithelial monolayers generated pronounced transepithelial solute gradients. The composition of the luminal (L) and basolateral (B) media after 48 h of incubation was as follows: [Na], L 119 +/- 1.1, B 145 +/- 3.0; [K], L 11.9 +/- 0.5, B 2.0 +/- 0.3; [PO4], L 2.8 +/- 0.2, B 7.3 +/- 0.3; [Cl], L 134.1 +/- 2.7 B 117.8 +/- 2.2, [mM]; [Ca], L 42.1 +/- 1.2, B 812 +/- 26, [microM]; pH, L 5.52 +/- 0.12, B 7.15 +/- 0.08. The transepithelial osmotic concentration difference was 14.3 +/- 3.5 mosmol/l. The amount of glucose at the luminal side remained unaltered, whereas glucose concentration at the basolateral side decreased from 21 to 7.7 +/- 1.0 mM. Lactic acid accumulated predominantly at the basolateral side (L 1.0 +/- 0.15, B 23.5 +/- 1.7 mM). These data indicate that primary cultures of immunodissected CCT cells retain many of their differentiated transport functions and thus should prove useful for studying the mechanisms of solute transport in the collecting duct system.

Animals↗
PubMed2005

TREM2, a DAP12-associated receptor, regulates osteoclast differentiation and function.

UNLABELLED: Deficiency of the signaling adapter protein DAP12 or its associated receptor TREM2 is associated with abnormal OC development in humans. Here we examine the role of TREM2 in mouse OC development and function, including migration and resorption in vitro. These results provide new evidence that TREM2 regulates OC function independent of its effects on multinucleated OC differentiation. INTRODUCTION: TREM2 (triggering receptor expressed in myeloid cells-2) associates with the signaling adapter DAP12 in osteoclasts (OCs). Genetic mutation or deletion of either the TYROBP (DAP12) or TREM2 gene is associated with the human disorder of brain and bone, Nasu-Hakola disease. We and others recently showed the critical requirement for immunoreceptor tyrosine-based activation motif (ITAM) signals through DAP12 and the Fc Receptor gamma chain (FcRgamma) during OC development. Here, we further define the role of TREM2 in OC differentiation and describe a role for TREM2 in OC migration and bone resorption. MATERIALS AND METHODS: We generated monoclonal anti-mouse TREM2 antibodies (mAb), analyzed pre-osteoclasts and mature OCs for TREM2 surface expression, and determined the effect of antibody ligation on in vitro OC differentiation, resorption, and migration. TREM2 RNA interference (RNAi) was used to disrupt expression of TREM2 in pre-osteoclasts. RESULTS: Using flow cytometry, our studies reveal that TREM2 is weakly expressed on C57BL/6 bone marrow macrophages (BMMs) and is upregulated during culture with RANKL and macrophage-colony stimulating factor (M-CSF). The expression of TREM2 is unaltered in DAP12-deficient OCs. Using C57BL/6 BMMs or RAW264.7 precursors, anti-TREM2 mAb treatment with RANKL and M-CSF enhances the formation of multinuclear TRACP+ OCs compared with control mAb treatment. In contrast, these agents have no effect on DAP12-deficient precursors. Monoclonal Ab blockade of TREM2 on OCs generated from C57BL/6 BMMs results in decreased resorption of artificial calcium-phosphate substrate and dentine. Reduction of TREM2 expression in RAW264.7 cells by RNAi results in loss of OC formation in response to RANKL and M-CSF. Anti-TREM2 cross-linking enhances migration of C57BL/6 OCs and RAW246.7 OCs in response to M-CSF. CONCLUSIONS: Our studies indicate that the TREM2 receptor regulates OC multinucleation as well as resorption and migration of mature OCs. Thus, TREM2-DAP12 signals regulate both OC formation and function.

Adaptor Proteins, Signal Transducing↗
PubMed1981

Differential effects of transforming avian RNA tumor viruses on avian macrophages.

Functionally differentiated chicken macrophages were derived by in vitro differentiation of embryonic yolk sac cells and were characterized by several macrophage-specific cell markers. Uniform, infected, virus-producing cultures were obtained after exposure of these macrophages to avian myoblastosis virus (AMV), avian myelocytomatosis virus (MC29), myeloblastosis-associated virus (MAV-2), and Prague strain of Rous sarcoma virus (PR-B RSV). Both AMV and MC29 induced morphological transformation typical of the in vivo leukemias induced by these virus strains. Analysis of the expression of macrophage-specific markers in these two transformed cell types demonstrated that different markers of the mature macrophage were suppressed by each virus, even though the parental cell immediately preceding the transformation event was a mature macrophage in both cases. Cells infected with PR-B RSV and MAV-2 showed no observable difference from uninfected macrophages in terms of morphological characteristics, growth rate, or expression of the differentiated functions of macrophages. Ths system provides demonstrations of a cell type that produces infectious, transforming RSV but fails to respond by functional alterations induced by the transforming gene, src.

Acid Phosphatase↗
PubMed1992

The performance of the probability density function in differentiating supraventricular from ventricular rhythms.

The ability of the probability density function (PDF) of an automatic implantable cardioverter defibrillator (AICD) to reject supraventricular arrhythmias being recognized as ventricular was evaluated in 12 patients who were treated with an AICD (Ventak P 1600). The PDF criterion was monitored via telemetry with the sinus rate during exercise test. PDF was satisfied in seven patients at a rate of 75-144/min (mean 109/min), and not in the remaining five patients (mean rate 141/min). PDF was fulfilled in five of ten patients at a lower heart rate than predicted by the duty cycle index, derived from the ventricular patch lead electrogram at the implantation. Thus PDF is often fulfilled already at a moderately elevated sinus rate. If used to prevent inadvertent AICD discharges during rapid supraventricular rhythms, its performance should be tested in the individual patient.

Electric Countershock↗
PubMed2001

Epithelial-stromal tissue interaction in paramesonephric (Müllerian) epithelial differentiation.

During organogenesis, the middle to caudal portion of Müllerian epithelium differentiates into uterine and vaginal epithelia in females. Functional differentiation of uterine and vaginal epithelia occurs in adulthood, and is regulated by 17beta-estradiol (E(2)) and progesterone. In this report, the roles of mesenchyme/stroma in differentiation of uterine and vaginal epithelia were studied in tissue recombination experiments. At birth, Müllerian epithelium was negative for uterine and vaginal epithelial markers. Tissue recombinant experiments showed that uterine and vaginal gene expression patterns were induced in neonatal Müllerian epithelium by the respective mesenchymes. Differentiated adult uterine and vaginal epithelia did not change their original gene expression in response to heterotypic mesenchymal induction. In the adult vagina, E(2) induced expression of involucrin, a CCAAT/enhancer-binding protein beta and cytokeratin 1 via estrogen receptor alpha (ERalpha). Tissue recombination experiments with wild-type and ERalpha knockout mice demonstrated that epithelial gene expression is regulated by E(2) via epithelial-stromal tissue interactions. Uterine/vaginal heterotypic tissue recombinations demonstrated that functional differentiation of uterine and vaginal epithelia required organ-specific stromal factors. In contrast, stromal signals regulating epithelial proliferation appeared to be nonspecific in the uterus and vagina.

Animals↗
PubMed1997

Integrators of epidermal growth and differentiation: distinct functions for beta 1 and beta 4 integrins.

Mammalian epithelia are critically dependent on interactions with components in the underlying basal lamina for proper morphogenesis and function. Substratum attachment is essential for survival, proliferation, movement, and differentiation; detachment compromises the cell's ability to perform these functions, often resulting in human disease. Interactions with the extracellular matrix are mediated through transmembrane integrin receptors that transmit signals to the cytoskeleton and to signaling molecules within the proliferating cells of the epithelium. In the past year, novel insights have emerged regarding the specific role of integrins in their attachment to extracellular matrix and in their signal transduction pathways within the epidermis.

Animals↗
PubMed1990

Discriminant functions in differential diagnosis of hypercalcemic patients.

Using readily available biochemical assays of plasma and urine constituents, we have defined discriminant functions useful as a guide to the differential diagnosis of patients with hypercalcemia. The decreasing rank order of contribution of the variables to the discriminant functions was as follows: plasma albumin, plasma phosphate, plasma chloride, log10 (calcium excretion per liter of glomerular filtrate), and log10 (plasma gamma-glutamyltransferase). Discriminant functions have been defined for patients with values for plasma creatinine above and below 185 mumol/L, and for practical conditions in which plasma and urine samples, or plasma samples only, are available.

Calcium↗
PubMed1985

C-reactive protein as an aid in the differentiation of functional and inflammatory bowel disorders.

Eighty-two patients were investigated on their first visit to the outpatient department of St. Mark's Hospital, London, for the assessment of abdominal symptoms. In addition to the clinical examination, a rectal biopsy, routine tests and appropriate special investigations, blood was taken from each patient for the determination of erythrocyte sedimentation rate, C-reactive protein and alpha-1-acid glycoprotein. Nineteen patients were finally diagnosed as having Crohn's disease, twenty-two ulcerative colitis, and forty-one functional bowel disorders. All the patients with Crohn's disease had an elevated erythrocyte sedimentation rate and C-reactive protein level as had 11 (50%) of the patients with ulcerative colitis, but none with functional disorders. All cases of ulcerative colitis could be diagnosed by rectal biopsy. Measurement of alpha-1-acid glycoprotein provided no additional diagnostic information. A combination of rectal biopsy, and measurement of the erythrocyte sedimentation rate and C-reactive protein successfully distinguishes between inflammatory disease of the large and small bowel and functional bowel syndrome.

Adult↗
PubMed1992

A functional model of adult human prostate epithelium. The role of androgens and stroma in architectural organisation and the maintenance of differentiated secretory function.

A functional model of adult human prostate epithelium is described. This model shows that stromal cells, but not an androgenic stimuli, are required for architectural organisation of prostate epithelium. Within an organised structure, androgenic stimulation is required for the establishment of secretory epithelial cell morphology and associated function. In the absence of stromal cells but in the presence of androgens architectural organisation and secretory function are lost. Epithelial parenchymal units (organoids) from human prostate tissue were isolated, cultured within a three-dimensional collagen matrix, and xenografted subcutaneously into athymic mouse hosts. The grafted gels were rapidly invaded by host fibroblasts. Epithelial organisation initially disappeared but was re-established concurrently with the stromal cell invasion. In intact male hosts, cuboidal and columnar cells that expressed human prostate-specific secretory markers were found. In castrated male and in female hosts epithelial structures were lined with flattened epithelium with no secretory function. This phenomenon could be reversibly replicated by treating intact male hosts with the anti-androgen Flutamide. Gels containing organoids grafted within 0.45 microns Millipore chambers were not invaded by stromal cells and rapidly lost all epithelial organisation and secretory function. When organoids cocultured with human foreskin fibroblasts were grafted within chambers, structural organisation of the epithelium was supported. These results indicate that both heterologous human fibroblasts and mouse stromal cells are capable of permissively supporting adult human prostate epithelial function.

Aged↗