Three-dimensional Collagen Gel Matrix Research Articles

Applied stretch initiates directional invasion via the action of Rap1 GTPase as a tension sensor

Although it is known that a stiffening of the stroma and the rearrangement of collagen fibers within the extracellular matrix facilitate the movement of tumor cells away from the primary lesion, the underlying mechanisms responsible are not fully understood. We now show that this invasion, which can be initiated by applying tensional loads to a three-dimensional collagen gel matrix in culture, is dependent on the Rap1 GTPases (Rap1a and Rap1b, referred to collectively as Rap1). Under these conditions Rap1 activity stimulates the formation of focal adhesion structures that align with the tensional axis as single tumor cells move into the matrix. These effects are mediated by the ability of Rap1 to induce the polarized polymerization and retrograde flow of actin, which stabilizes integrins and recruits vinculin to preformed adhesions, particularly those near the leading edge of invasive cells. Rap1 activity also contributes to the tension-induced collective invasive elongation of tumor cell clusters and it enhances tumor cell growth in vivo Thus, Rap1 mediates the effects of increased extracellular tension in multiple ways that are capable of contributing to tumor progression when dysregulated.

Proteolytic and Non-proteolytic Activation of Keratinocyte-Derived Latent TGF-β1 Induces Fibroblast Differentiation in a Wound-Healing Model Using Rat Skin

Transforming growth factor-β1 (TGF-β1) reportedly causes the differentiation of fibroblasts to myofibroblasts during wound healing. We investigated the mechanism underlying the activation of latent TGF-β1 released by keratinocytes in efforts to identify promising pharmacological approaches for the prevention of hypertrophic scar formation. A three-dimensional collagen gel matrix culture was prepared using rat keratinocytes and dermal fibroblasts. Stratified keratinocytes promoted the TGF receptor–dependent increase in α-smooth muscle actin (α-SMA) immunostaining and mRNA levels in fibroblasts. Latent TGF-β1 was found to be localized suprabasally and secreted. α-SMA expression was inhibited by an anti-αv-integrin antibody and a matrix metalloproteinase (MMP) inhibitor, GM6001. In a two-dimensional fibroblast culture, α-SMA expression depended on the production of endogenous TGF-β1 and required αv-integrin or MMP for the response to recombinant latent TGF-β1. In keratinocyte-conditioned medium, MMP-dependent latent TGF-β1 secretion was detected. Applying this medium to the fibroblast culture enhanced α-SMA production. This effect was decreased by GM6001, the anti-αv-integrin antibody, or the preabsorption of latent TGF-β1. These results indicate that keratinocytes secrete latent TGF-β1, which is liberated to fibroblasts over distance and is activated to produce α-SMA with the aid of a positive-feedback loop. MMP inhibition was effective for targeting both keratinocytes and fibroblasts in this model. [Supplementary Figure: available only at http://dx.doi.org/10.1254/jphs.13209FP]

A dialog between glioma and microglia that promotes tumor invasiveness through the CCL2/CCR2/interleukin-6 axis

Glioma cells in situ are surrounded by microglia, suggesting the potential of glioma-microglia interactions to produce various outcomes. As chemokines are important mediators of cell-cell communication, we sought first to identify commonly expressed chemokines in 16 human glioma lines. We found CCL2 (macrophage chemoattractant protein-1) messenger RNA to be expressed by the majority of glioma lines. However, these lines did not express the CCL2 receptor, CCR2, which was found on microglia. Next, we overexpressed CCL2 in the U87 glioma line, which has low basal level of CCL2, to investigate the hypothesis that glioma-secreted CCL2 interacts with microglia to affect glioma growth. Stable clones with 10- to 12-fold elevation of CCL2 have similar growth rate and invasive capacity as vector controls when cultured in isolation. However, in coculture with microglia in a three-dimensional collagen gel matrix, the invasiveness of CCL2-overexpressing clones was increased. Gene array analyses were then undertaken and they revealed that interleukin (IL)-6 was consistently increased in the coculture. Recombinant IL-6 enhanced the invasiveness of glioma cells when these were cultured alone, whereas a neutralizing antibody to IL-6 attenuated the microglia-stimulated glioma invasiveness. Finally, we found that human glioma specimens in situ contained IL-6 immunoreactivity that was expressed on CD68+ cells. This study has uncovered a mechanism by which glioma cells exploit microglia for increased invasiveness. Specifically, glioma-derived CCL2 acts upon CCR2-bearing microglia, which then produces IL-6 to stimulate gliomas. The CCL2/CCR2/IL-6 loop is a potential therapeutic target for the currently incurable malignant gliomas.

Stroma-Derived Matrix Metalloproteinase (MMP)-2 Promotes Membrane Type 1-MMP–Dependent Tumor Growth in Mice

Matrix metalloproteinase-2 (MMP-2) is a stroma-derived MMP belonging to the type IV collagenase family. It is believed to mediate tumor cell behavior by degrading deposits of type IV collagen, a major component of the basement membrane. The membrane type 1-MMP (MT1-MMP) is a highly potent activator of MMP-2 and is expressed in many tumor and stromal cells. However, the roles played by stromal MMP-2 in tumor progression in vivo remain poorly understood. We established a colon epithelial cell line from an Mt1-mmp(-/-) mouse strain and transfected these cells with an inducible expression system for MT1-MMP (MT1rev cells). Following s.c. implantation into Mmp-2(+/+) mice and induction of MT1-MMP expression, MT1rev cells grew rapidly, whereas they grew very slowly in Mmp-2(-/-) mice, even in the presence of MT1-MMP. This MT1-MMP-dependent tumor growth of MT1rev cells was enhanced in Mmp-2(-/-) mice as long as MMP-2 was supplied via transfection or coimplantation of MMP-2-positive fibroblasts. MT1rev cells cultured in vitro in a three-dimensional collagen gel matrix also required the MT1-MMP/MMP-2 axis for rapid proliferation. MT1rev cells deposit type IV collagen primarily at the cell-collagen interface, and these deposits seem scarce at sites of invasion and proliferation. These data suggest that cooperation between stroma-derived MMP-2 and tumor-derived MT1-MMP may play a role in tumor invasion and proliferation via remodeling of the tumor-associated basement membrane. To our knowledge, this is the first study demonstrating that MT1-MMP-dependent tumor growth in vivo requires stromal-derived MMP-2. It also suggests that MMP-2 represents a potential target for tumor therapeutics.

In vitro spermatogenesis by three-dimensional culture of rat testicular cells in collagen gel matrix

In an effort to improve in vitro spermatogenesis by potentiating the interactions between developing germ cells, somatic cells, and the extracellular matrix (ECM), the efficiency of the germ cell-somatic cell coculture in a three-dimensional (3D) collagen gel matrix was examined. Cells isolated from rat seminiferous tubules 18 days after birth were cultured for 22 days in a monolayer without ECM, collagen gel (CG), or collagen+Matrigel (CGM). After culture, the viabilities of the cultured cells in the monolayer, CG, and CGM culture were 42.8%, 70.7% and 76.1%, respectively. Occludin-positive cells in a cyst-like structure were found in the ECM gel matrix together with 3 β hydroxysteroid dehydrogenase-positive cells, suggesting the presence of functional Sertoli cells and Leydig cells, respectively. Flow cytometric analysis of DNA content revealed a significant increase in the haploid cell population in the CG and CGM compared to the monolayer culture. Transition protein 2 (TP2) and protamine 2-positive cells were found together with a significant increase in TP2 mRNA levels in cells cultured in CG and CGM over those in monolayer culture, suggesting the occurrence of the post-meiotic differentiation of spermatogenetic cells. Taken together, a 3D in vitro culture system for testicular cells using a collagen gel matrix could enhance viability, meiosis, and post-meiotic differentiation of germ cells to presumptive differentiating spermatids.

Mature adipocytes, but not preadipocytes, promote the growth of breast carcinoma cells in collagen gel matrix culture through cancer-stromal cell interactions.

Interaction between cancer and stromal cells is critical for tumour cell growth and invasion. It has recently been suggested that mature adipocytes, a specific type of stromal cell that is abundant in the breast, affect the biological behaviour of some epithelial cell types. However, the nature of the interaction between mature adipocytes and breast cancer cells remains unclear. The present study has examined the effects of mature rat adipocytes, as the main cell type in adipose tissue, on the growth, apoptosis, and cell adhesion of breast carcinoma cell lines [human oestrogen receptor (ER)-positive cell lines MCF-7, ZR75-1, and T47-D; and the ER-negative mouse cell line MMT 060562] by analysing bromodeoxyuridine (BrdU) uptake, apoptotic indices, and immunohistochemical expression of E-cadherin. As a reference, the effects of rat preadipocytes (immature adipocytes) on the behaviour of the cell lines were examined. The cell lines were cultured in a three-dimensional collagen gel matrix with mature adipocytes or preadipocytes. Mature adipocytes significantly promoted BrdU uptake by all cell lines other than MMT 060562 cells. Preadipocytes decreased the uptake of T47-D cells and had no effect on that of MCF-7, ZR75-1 or MMT 060562 cells. Mature adipocytes or preadipocytes did not affect the apoptotic indices of any of the cell lines. Mature adipocytes did not influence E-cadherin expression in any of the cell lines, but preadipocytes clearly promoted E-cadherin expression by MCF-7 and T47-D cells, but not by R75-1 and MMT 060562 cells. These data suggest that mature adipocytes may be involved in the mechanisms regulating the growth of breast cancer mass through their growth-promoting effect on ER-positive tumour cells.

Prostate cancer cell growth is modulated by adipocyte-cancer cell interaction.

To assess whether adipocytes (mesenchymal stromal cells thought to affect the proliferation and differentiation of epithelial cells) affect the behaviour of prostate cancer cells in vitro, as prostate cancer metastasizes to the bone, which is an adipocyte-rich environment. The human bone-metastatic prostate carcinoma cell line PC3 was cultured with or without adipocytes in a three-dimensional collagen gel matrix. Histological and immunohistochemical assays were used to evaluate the proliferation and differentiation of PC3 cells. The cytokine expression of this culture assembly was also examined by reverse transcription-polymerase chain reaction (RT-PCR). The proliferation and differentiation of cancer cells were clearly changed on co-culture with adipocytes compared with the control cultures. The mean (range) bromodeoxyuridine (BrdU) indices estimated (according to uptake) to evaluate the growth of the cultured cells were 36.3 (8.55)% in the co-culture and 26.95 (10.50) in the control (P < 0.02). PC3 cells in co-culture formed larger clusters than in the control, at 16.0 (11.0) vs 14.0 (10.0), respectively (P < 0.01). Cancer cells also showed pleomorphism, varying from cuboidal to spindle-shaped. The expressions of vascular endothelial and platelet-derived growth factor were greater in co-culture than in the control. These findings suggest that adipocytes modulate the growth, morphology and cytokine expression of prostate cancer cells. This specific mesenchymal stromal cell type is important in the biological behaviour of prostate cancer cells.

Morphogenesis of MDCK cells in a collagen gel matrix culture under stromal adipocyte-epithelial cell interaction

The stromal-epithelial cell interaction is essential for epithelial morphogenesis. Recently, the specific stromal cell type adipocytes, which abundantly exist in perirenal adipose tissue, have been suggested to affect the biological behavior of some epithelial cell types. However, adipocyte-renal epithelial cell interaction remains unclear. We thus examined the effects of adipocytes on the morphogenesis of renal epithelial cells. The renal epithelial cell line, Madin-Darby canine kidney (MDCK), cells were cultured in three-dimensional collagen gel matrix with or without mature unilocular adipocytes. Cultures cells were examined by histochemistry, immunohistochemistry, and electron microscopy. Adipocytes extensively promoted the tubule formation of MDCK cells in two different manners. In the first type, after approximately 20% of MDCK cells actively adhered to adipocytes; they organized double-cell structured tubules between the adipocytes and the gel, contacting directly with the entire surface of the adipocytes. In the second type, approximately 70% of MDCK cells apart from adipocytes also formed tubules that had no contact with adipocytes. The component cells of both tubule types at the apical side showed microvilli and peanut agglutinin lectin-positive stain. These cells at the basal side had the basal lamina and type IV collagen-positive stain. These results indicate that the specific stromal cell type adipocytes cause MDCK cells to organize the well-polarized tubular structures in two different manners according to their direct and indirect interactions, suggesting that adipocytes may be involved in the regulatory mechanism of renal epithelial morphogenesis.

Subcutaneous Adipocytes Promote the Differentiation of Squamous Cell Carcinoma Cell Line (DJM-1) in Collagen Gel Matrix Culture

Cancer cell-stromal cell interaction plays a crucial role in the malignant growth of cancer cells. In the skin, the main stromal cell types consist of dermal fibroblasts and subcutaneous adipocytes. Fibroblasts are shown to promote the invasive growth of various cancer cell types. The interaction between cancer cells and stromal adipocytes, however, has not been sufficiently studied even in cutaneous carcinoma. To address the effects of adipocytes on the biologic behavior of cancer cells, we examined the growth and differentiation of a squamous cell carcinoma cell line of the skin (DJM-1), using a three-dimensional collagen gel matrix culture with a cutaneous environmental factor, air exposure. The growth was estimated by the uptake of bromodeoxy-uridine (BrdU) for 24 h. The BrdU indices of DJM-1 cells in stromal-cell-free, fibroblast-containing, and adipocyte- containing conditions were 19.7 +/- 1.9%, 19.8 +/- 2.8%, and 4.7 +/- 1.4%, respectively, whereas the BrdU index on the gel containing both fibroblasts and adipocytes was 10.4 +/- 3.3%. In terms of differentiation, DJM-1 cells cocultured with adipocytes constructed the best-organized stratified layer with a cornified-like structure in all conditions above. The differentiation markers involucrin and cytokeratin 10 were immunohistochemically detected in this structure of DJM-1 cells. Adipocyte-induced phenomena were not affected distinctively by air exposure. These results indicate that adipocytes, but not fibroblasts, promote the differentiation of squamous cell carcinoma cells (DJM-1) and inhibit their growth. These adipocyte-induced phenomena were not completely inhibited by fibroblasts. In conclusion, we suggest that stromal adipocytes may be involved in the differentiating mechanisms of cutaneous carcinoma cells.

Effects of fat cells on keratinocytes and fibroblasts in a reconstructed rat skin model using collagen gel matrix culture

Fat cells (stromal tissue cells), not only have the function of lipid metabolism, but produce various cytokines that exert an influence on other cell types through paracrine or endocrine mechanisms. To elucidate possible roles of fat cells in the skin, we examined their effects on the biological behaviour of keratinocytes and dermal fibroblasts in culture. In the present study, focusing upon fat cell--keratinocyte or fat cell--dermal fibroblast interactions, we used a reconstructed skin system with rat skin cells in a three-dimensional collagen gel matrix culture. In this coculture system, fat cells promoted the proliferation and differentiation of keratinocytes. When keratinocytes were seeded directly on the fat cell layer without dermal fibroblasts, they proliferated extensively and formed a thick epidermal layer with a well-differentiated structure. Conversely, fat cells inhibited the proliferation of dermal fibroblasts. These effects of fat cells were presumed to be mediated by cytokines derived from the fat cells. The effects of fat cells could not be mimicked by the addition of leptin, tumour necrosis factor-alpha or insulin-like growth factor-II, suggesting that fat cells are mediating these activities via some other cytokines.

Transformation of Madin-Darby canine kidney (MDCK) epithelial cells by Epstein-Barr virus latent membrane protein 1 (LMP1) induces expression of Ets1 and invasive growth.

The Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) has a significant role in initiating EBV-associated lymphoproliferative disease and EBV-related malignancies. In view of clinical features related to the type of EBV latency, LMP1 may influence invasiveness of EBV associated tumors categorized as types II and III as represented on nasopharyngeal carcinoma (NPC). To screen for genes associated with invasion of epithelial cells transformed by LMP1, Madin-Darby canine kidney (MDCK) epithelial cells were transformed by LMP1. Stable transfection of a LMP1 gene into MDCK cells induced morphological change from cobblestone to a long spindle-shape, reduced cell-cell adhesion and caused high cell motility. Parental MDCK cells, which form spherical cysts in three-dimensional collagen gel matrix, form branching tubules following exposure to hepatocyte growth factor (HGF). MDCK cells transformed by LMP1 showed invasive growth to form branching tubules into collagen gel without HGF-treatment. mRNA differential display and Northern hybridization identified plasminogen activator inhibitor-1 (PAI-1), urokinase type plasminogen activator (uPA) and ets1 as genes upregulated during transformation by LMP1. Expression of a dominant negative type of Etsl in LMP1-transformed cells downregulated uPA expression and cell motility. Deletion of LMP1 cytoplasmic carboxy-terminal activating region 1 (CTAR1) domain abolished transformation, but a deletion mutant lacking CTAR2 domain still retained transforming and uPA-inducing ability. Expression of Ets1 was immunolocalized in tumor cells of NPC tissue which frequently express LMP1. Taken together, it is suggested that LMP1 induces expression of Ets1 which may contribute to invasion of NPC by stimulating cell motility and uPA expression.

Proliferation and differentiation of rat dorsal prostatic epithelial cells in collagen gel matrix culture, focusing upon effects of adipocytes.

Prostatic epithelial cells organize functional acinus structures under epithelial extracellular matrix and epithelial-stromal cell interactions. Recently, the adipose tissue, which surrounds and even exists within the prostate, has been suggested to affect the differentiation and proliferation of some cell types. Therefore, tissue fragments, which consist mainly of epithelial and fibromuscular stromal cells, were cultured in three-dimensional collagen gel matrix culture with adipocytes. Tissue fragments of rat dorsal prostate, including both epithelial and fibromuscular stromal components, were cultured in collagen gel with or without adipocytes. Epithelial cell differentiation was evaluated with the reconstruction of acinus-like structures and with immunohistochemistry of rat dorsal prostate-specific proteins, dorsal protein-1 and probasin. The proliferation was examined by uridine uptake. Under coculture of the fragments and adipocytes, epithelial cells reconstructed more differentiated acinus-like structures surrounded by fibromuscular stromal cells than tissue fragment culture without adipocytes. Dorsal protein-1 and probasin expressions of epithelial cells in this coculture system were the same as in rat prostate in vivo. In the coculture, epithelial cells had a higher proliferation activity. These results indicate that adipocytes promote proliferation and differentiation of prostatic epithelial cells. Our new culture model with adipocytes suggests the importance of cell-cell interactions, including those of epithelial cells and adipocytes.

Reconstruction of pleomorphic adenoma of the salivary glands in three-dimensional collagen gel matrix culture.

The morphogenesis of salivary gland pleomorphic adenoma was examined in vitro using three-dimensional (3-D) collagen gel culture. Pleomorphic adenoma cells were isolated from three parotid gland tumours and cultured as monolayers, after which they were subcultured in floating-collagen gel sandwiches. Cells cultured in both conditions were immunohistochemically characterized and compared using antibodies against various proteins representative of each histological component of salivary glands. Monolayers had myoepithelial characteristics, being positive for vimentin and alpha-smooth muscle actin. In collagen gels, however, the cells assembled in epithelial nests, showing an architecture similar to that of pleomorphic adenoma. The nests were composed of duct-lining epithelial cells that were positive for epithelial markers, surrounded by myoepithelial cells. Collagen gel culture induces multidirectional differentiation of adenoma cells, suggesting that pleomorphic adenomas originate from stem or reserve cells.

Proliferation and differentiation of unilocular fat cells in the bone marrow.

Fat cells contribute not only to systemic lipid metabolism, but also to osteogenesis and hemopoiesis in the bone marrow. The present study represents the first attempt to culture mature unilocular fat cells of the bone marrow. Two methods devised in our laboratory were employed: one is the "ceiling culture method" that utilizes the floating property of the cells; the other, a three-dimensional collagen gel matrix culture that captures unilocular fat cells in the gel matrix. Using these methods, the proliferation of unilocular fat cells from the bovine metacarpal bone marrow was demonstrated. First, we confirmed the proliferative ability of unilocular fat cells derived from the bone marrow, using autoradiography to study 3H-thymidine incorporation into the nuclei. The unilocular fat cells de-differentiated into fibroblast-like fat cells and then proceeded to proliferate. When they underwent a contact inhibition of growth, re-differentiation from fibroblast-like fat cells into unilocular fat cells occurred at a high rate. A specific enzymatic marker of the fat cell, alpha-glycerophosphate dehydrogenase activity related to lipogenesis, was then demonstrated in the cultured fat cells. We examined the functional reactivity of the fat cells by treatment with insulin and cyclic-AMP, and both lipogenesis and lipolysis were also confirmed in them. We concluded that unilocular fat cells from the bone marrow de-differentiated, proliferated and re-differentiated in culture. The present results may help to clarify the various functions of fat cells in the bone marrow.

Membrane Type 1-Matrix Metalloproteinase Is Involved in the Formation of Hepatocyte Growth Factor/Scatter Factor-Induced Branching Tubules in Madin-Darby Canine Kidney Epithelial Cells

Matrix metalloproteinases (MMPs) are believed to be involved in morphogenesis. Association of MMPs in a model of kidney tubulogenesis was studied using Madin-Darby canine kidney (MDCK) epithelial cells in anin vitromorphogenetic system. MDCK cells form branching tubules in three-dimensional collagen gel matrix in the presence of hepatocyte growth factor (HGF). The addition of specific MMP inhibitor BB-94 and tissue inhibitor MMP (TIMP)-2 but not TIMP-1 to such collagen gel cultures reduced the formation of branching tubules induced by HGF. The induction of membrane-type 1-matrix metalloproteinase (MT1-MMP) mRNA expression was observed in MDCK cells cultured in the collagen gel. Stable expression of MT1-MMP antisense RNA interfered with the tubule formation of MDCK cells induced by HGF-collagen gel culture. These observations implicate MT1-MMP in kidney tubulogenesis and TIMP-2-specific inhibition suggests a direct role of MT1-MMP rather than a gelatinase A-mediated effect.

Proliferation and differentiation of organoid hair follicle cells co-cultured with fat cells in collagen gel matrix culture.

Using rat skin, we studied the influence of fat cells on the proliferation and differentiation of organoid hair follicle cells in a three-dimensional collagen gel matrix culture system. We cultured organoid hair follicles embedded in collagen gel under each of the following three conditions: cell-free collagen gel for control experiments (condition 1); co-culture with fat cells in close apposition (condition 2); and co-culture with fat cells in spatial separation (condition 3). Outgrowths of epithelial cells from the organoid hair follicles associated with perifollicular proliferation of fibroblasts were observed under conditions 1 and 3. Under condition 2, proliferation of both organoid hair follicle cells and fibroblasts was inhibited, but differentiation of the hair follicle cells appeared to be accelerated. Fat cells are considered to have an inhibitory effect on the proliferation of perifollicular fibroblasts, which might have resulted in the inhibition of hair follicle cell proliferation and also in the better maintenance of normal follicular structure and integrity, allowing for hair-type differentiation to proceed. A direct accelerating effect of fat cells on hair follicle differentiation may also have been responsible. In a physiological state (co-culture with keratinocytes on the collagen gel), similar results were observed under conditions 1 and 2. The different findings under conditions 2 and 3 may be due to either of two possibilities: either the concentration gradient of the soluble factors released from fat cells, acting on either the hair follicle cells or the perifollicular fibroblasts as an inhibitor of proliferation, caused the difference in the results, or direct contact between the organoid hair follicle cells and fat cells may have influenced the accelerating effect of fat cells on the differentiation of hair follicle cells.

Effects of Hepatocyte Growth Factor, Transforming Growth Factor-β1 and Epidermal Growth Factor on Bovine Corneal Epithelial Cells under Epithelial–Keratocyte Interaction in Reconstruction Culture

In the cornea, corneal epithelial cells are in close contact with keratocytes: the epithelial cells organize thickened lamellar structure on a layer of keratocytes embedded in extracellular matrix (ECM). Thus, growth factors are expected to critically regulate corneal component cells under epithelial–keratocyte interaction. The purpose of this study is to clarify effects of hepatocyte growth factor (HGF), transforming growth factor-β1 (TGF-β1) or epidermal growth factor (EGF) on corneal epithelial cells under epithelial–keratocyte interaction. We examined proliferation and differentiation of the epithelial cells in a simple corneal reconstruction culture composed of an epithelial cell layer on the keratocyte-containing stromal layer, using three-dimensional collagen gel matrix culture. We observed the morphological change by phase contrast microscopy, and conducted histological and immunohistochemical examinations. The epithelial proliferation was examined by nuclear bromodeoxy-uridine (BrdU) uptake. In the reconstructed cornea under epithelial–keratocyte interaction, EGF-, TGF-β1- and HGF-treated cells formed a thickened epithelial layer consisting of 5–6, 5–6 and 3–4 cells, respectively. In fact, both EGF and TGF-β1 induced significantly higher intakes of nuclear BrdU of the epithelial cells than HGF. In lamellar differentiation of the epithelial cells, TGF-β1- or HGF-treated cells formed a triple lamellar structure specific for the in vivo corneal epithelium: basal, middle and superficial layers are composed of cuboidal basal-like cells, spindle wing-like cells and flat superficial-like cells, respectively. TGF-β1-treated cells formed a more markedly thickened epithelial layer than HGF-treated cells. In contrast, EGF formed a single lamellar structure consisting of cuboidal cells. These results suggest that those growth factors regulate proliferation and/or lamellar differentiation of corneal epithelial cells under epithelial–keratocyte interaction. The most interesting result was that TGF-β1 promotes proliferation and lamellar differentiation of corneal epithelial cells through keratocyte-mediated stimulation.

Reconstruction of Peritoneal-like Structure in Three-Dimensional Collagen Gel Matrix Culture

The peritoneum is a serous membrane consisting of different kinds of cells and extracellular matrix components (ECM). The aim of the present study was to develop a three-dimensional (3D)in vitroculture system for possible investigation of pathological conditions of the peritoneum. Human omental mesothelial cells (MC) and endothelial cells from the umbilical vein (EC) were cultivated eitheron(MC) orin(EC) a preformed type I collagen matrix. In 3D culture mesothelial cells showed their phenotypicalin vivocharacteristics and the synthesis of a new basal membrane (BM). Endothelial cells developed vessel-like structures, produce a BM and express E-selectin after TNF-α stimulation. This 3D culture system presents extended possibilities for analyzing mesothelial and endothelial cell behavior as well as the cell–cell and cell–matrix interactions involved in several pathological processes in the peritoneum.

Reconstruction of prostatic acinus-like structure from ventral and dorsolateral prostatic epithelial cells of the rat in three-dimensional collagen gel matrix culture.

The study was carried out to reconstruct a prostatic acinus-like structure from prostatic epithelial cells in a new culture system which can provide a more physiological condition than conventional cell culture methods. Prostatic epithelial cells were isolated from ventral and dorsolateral prostates of the rat and were separately cultured in three-dimensional collagen gel matrix. The cultured cells were observed by photo-microscopy and transmission electron microscopy. Differentiation and proliferation of the cultured cells were examined by immunohistochemistry using PAP and PSA kits and a bromodeoxy-uridine (BrdU) kit. The cell area of acinus-like structures in the transverse sections was measured by computer with the Interaktive Bild-Analyse System. Dissociated prostatic epithelial cells were organized into three-dimensional spherical or branching cellular aggregates in collagen gel matrix. Through cell proliferation and differentiation, the cellular aggregates formed prostatic acinus-like structures, which consisted of a small intercellular lumen enclosed by one layer of cuboidal epithelial cells. The epithelial cells were connected together by junctional complexes, had microvilli at the luminal surface, and the basal side was surrounded by a distinct basal lamina. In the lumina of acinus-like structures, secretory products were often found. Prostatic acinus-like structures were reconstructed from dissociated prostatic epithelial cells in three-dimensional collagen gel matrix culture. The reconstructed acinus-like structures are similar to prostatic acini in vivo in structure and function. This three-dimensional collagen gel matrix culture model may provide a useful means for investigating prostatic diseases and influences that hormones and growth factors exert on prostatic epithelial cells.

Reconstruction of Prostatic Acinus-Like Structure from Ventral and Dorsolateral Prostatic Epithelial Cells of the Rat in Three-Dimensional Collagen Gel Matrix Culture

Reconstruction of Prostatic Acinus-Like Structure from Ventral and Dorsolateral Prostatic Epithelial Cells of the Rat in Three-Dimensional Collagen Gel Matrix Culture