In vitro canine oocyte nuclear maturation in homologous oviductal cell co-culture with hormone-supplemented media

The aim of the present research was to verify the influence of oviductal cell co-culture previously supplemented with steroids (estrogen, progesterone, or both) on IVM rates for oocytes from anestrous bitches that were cultured in vitro for 48, 72 and 96 h. Oocytes harvested from anestrous bitches were selected and allocated into four groups: Group 1 (co-culture in oviductal epithelial cells without hormonal supplementation-control); Group 2 (estrogen supplementation); Group 3 (progesterone supplementation); Group 4 (estrogen+progesterone supplementation). The oviductal epithelial cell culture was established 72 h prior to oocyte co-culture. After periods of 48, 72 and 96 h, the degree of oocyte nuclear maturation was assessed. Co-culture in oviductal epithelial cells with estrogen was not as beneficial for canine IVM as supplementation with progesterone and estrogen, or progesterone supplementation alone. Therefore, it was feasible to use co-culture with oviductal epithelial cells obtained from anestrous bitches for IVM (monolayer culture with oviduct cells previously supplemented with progesterone). Final stages of oocyte maturation were achieved at 72 and 96 h of culture; therefore, the duration of maturation for oocytes obtained from bitches in different stages of the estrous cycle should be taken into account.     

Effect of oviductal epithelial cells on fertilization of pig oocytes in vitro

The incidence of polyspermy is reduced by co-culture of pig oocytes with oviductal cells. It is not known whether the effect is due to soluble factors secreted into the medium. Oviductal epithelial cell monolayers and cell-conditioned media were prepared and their effects on fertilization of pig oocytes were examined. In vitro matured pig oocytes were inseminated with ejaculated boar spermatozoa at a concentration of 1 x 10(5) or 1 x 10(6) cells/ml and co-cultured in one of 5 culture systems: an oviductal epithelial cell monolayer, a fibroblast monolayer, an oviductal epithelial cell-conditioned medium, or a fibroblast-conditioned medium, and medium alone (modified-TCM199). In all 5 systems, the majority (range 85 to 100%) of the oocytes were penetrated by sperm. When oocytes were inseminated with spermatozoa at a concentration of 1 x 10(5) cells/ml, the percentages of monospermic oocytes were significantly higher in the oocytes co-cultured with oviductal epithelial cells and fibroblasts than that of the oocytes cultured without these cells. In contrast, when oocytes were inseminated with spermatozoa at a concentration of 1 x 10(6) cells/ml, the percentages of monospermic oocytes were significantly higher in the oocytes co-cultured with epithelial cells than those cultured with the fibroblasts and in the control medium. The suppressive effect on polyspermy was observed in the oviductal epithelial cells-conditioned medium when oocytes were inseminated with spermatozoa at both concentrations of 1 x 10(5) and 1 x 10(6) cells/ml. The effect was absent in the fibroblasts-conditioned medium. Moreover, the effect of the epithelial cells was maintained during the culture period, whereas the proportion of monospermic oocytes co-cultured with fibroblasts showed a gradual decrease, reaching 0% after 16 h. These results suggest that a soluble factor(s) derived from the oviductal epithelial cells decreased the number of spermatozoa penetrating the oocytes without suppressing the high rate of fertilization.     

Culture of one-cell bovine embryos in explanted mouse oviduct and bovine oviductal epithelial cells

One-cell bovine embryos fertilized in vivo were cultured in TCM-199 and bovine oviductal epithelial cells, in TCM-199, or in explanted immature mouse oviducts supported by TCM-199 to compare development to the blastocyst stage. The morphological stage of development and cell number were determined following 144 hours of culture. Of the embryos that cleaved at least once, 52.6, 30.4 and 0.0% developed to the morula/blastocyst stage after culture in oviductal epithelial cells, in TCM-199 alone, or in explanted mouse oviducts, respectively. The mean total cell number for embryos cultured in oviductal epithelial cells (24.5) was higher than for embryos cultured in TCM-199 (12.8) or in explanted mouse oviducts (5.9; P<0.05). The mean cell number of embryos cultured in TCM-199 or in explanted mouse oviducts did not differ. The explanted immature mouse oviduct supported by TCM-199 did not provide an environment adequate for development of one-cell bovine embryos to the blastocyst stage. Development of one-cell bovine embryos was best supported by co-culture with oviductal epithelial cells in TCM-199 medium.     

Characterization of newly established clonal oviductal cell lines and differential hormonal reculation of gene expression

Summary Oviductal functions have been studied mainly in primary epithelial cell culture and organ culture. However, secretory cells and ciliated cells coexist in the epithelium, and the small size of the oviduct limits the sources of both epithelial and stromal cells. To circumvent the limits, we attempted to establish clonal cell lines from an oviduct of a p53-deficient mouse. An oviduct was enzymatically digested and cultured in medium containing 10% fetal calf serum supplemented with estradiol-17β. Morphologically distinct clones (10 epithelial and 4 fibroblastic clones) were established, and all clones expressed estrogen receptor α and progesterone receptor. Expression of a mouse oviduct-specific glycoprotein gene as a marker of secretory cells was limited in one clone and was stimulated by estrogens and suppressed by progesterone. Expression of helix factor hepatocyte nuclear factor/forkhead homologue-4 gene as a marker of ciliated cells was limited in two clones and was suppressed by estrogens. The two genes were never coexpressed in any clones. The results strongly suggest that the oviductal epithelium consists of two functionally determined populations. To our knowledge, this is the first establishment of functional clonal cell lines of the oviduct and makes it possible to study independently two oviductal functions, secretion and ciliogenesis.     

Construction of an apparatus for perfusion cell cultures which enables in vitro experiments under organotypic conditions.

The value of cultured cells in cell biological, pharmaceutical or biotechnological research depends on the degree of terminal cell differentiation. In conventional Petri dishes or tissue culture plates it is often difficult to achieve culture conditions which resemble the in situ situation of intact tissue, as regards optimal cell adhesion, exchange of nutrients and metabolic products. These limitations prompted us to develop simple laboratory tools which optimize the environment of cultured cells. A perfusion apparatus with various culture containers and compatible cell holder sets was constructed which allows the simulation of organotypic conditions. (i) The cells can be kept on individual and interchangeable support materials for an optimal cell attachment. (ii) Culture medium can be perfused during the whole culture period. (iii) One type of the new culture container can be perfused with different media at the apical and basal side of the cells, thus mimicking the organotypic environment that applies for epithelial monolayers. Cell culture experiments with renal collecting duct epithelia exhibited an excellent morphological appearance showing typical features of principal and intercalated cells.     

Selective isolation and culture of a proliferating epithelial cell population from the hamster trachea

Summary A reliable cell isolation technique was developed to allow the cultivation of cells from the hamster respiratory tract. Repeated thermolysin treatments and gradient centrifugation yielded a cell culture completely free from contamination by fibroblasts. Viable cells could be isolated from as little tissue as a single hamster trachea, but in vitro proliferation occurred only if the hamster was less than 4 months of age. The cultured cells could be repeatedly passaged and subcultured for weeks by employing normal tissue culture techniques. Morphologically, the monolayers appeared to be a homogeneous population of epithelial cells, and successful cloning of freshly isolated single cells resulted in apparently identical cultures. The epithelial origin of these cells was also suggested by continued growth in minimum essential medium withd-valine substituted forl-valine. The relative ease with which this cell type can be isolated, cultured, and manipulated in vitro should encourage its application as a model of the respiratory epithelium. This research was supported by Public Health Service Grant P50-HL 19171 and Research Career Development Award 1-K04-AI 00178 to J. B. B.     

The immunohistochemical characterisation of an SV40-immortalised human corneal epithelial cell line

Alternatives to the Draize rabbit eye irritation test are currently being investigated. Because of morphological and biochemical differences between the rabbit and the human eye, continuous human cell lines have been proposed for use in ocular toxicology studies. Single cell-type monolayer cultures in culture medium have been used extensively in ocular toxicology. In the present study, an SV40-immortalised human corneal epithelial (HCE) cell line was characterised immunohistochemically, by using 13 different monoclonal antibodies to cytokeratins (CKs), ranging from CK3 to CK20. The results from the monolayer HCE cell cultures were compared with those from the corneal epithelium of human corneal cryostat sections. Previous studies have shown that the morphology of the HCE cell is similar to that of primary cultured human corneal epithelial cells, and that the cells express the cornea-specific CK3. In the study reported here, we show that the cell line also expresses CKs 7, 8, 18 and 19. These CKs are typically expressed by simple epithelial cells, and are not found in the human cornea in vivo. Therefore, the monolayer HCE cell line grown in culture medium does not express the CK pattern that is typical of human corneal epithelium. This should be taken into consideration when using HCE cell cultures in similar single cell-type experiments for ocular toxicology.     

Selective isolation and culture of a proliferating epithelial cell population from the hamster trachea

A reliable cell isolation technique was developed to allow the cultivation of cells from the hamster respiratory tract. Repeated thermolysin treatments and gradient centrifugation yielded a cellculture completely free from contamination by fibroblasts. Viable cells could be isolated from as little tissue as a single hamster trachea, but in vitro proliferation occurred only if the hamster was less than 4 months of age. The cultured cells could be repeatedly passaged and subcultured for weeks by employing normal tissue culture techniques. Morphologically, the monolayers appeared to be a homogeneous population of epithelial cells, and successful cloning of freshly isolated single cells resulted in apparently identical cultures. The epiethelial origin of these cells was also suggested by continued growth in minimum essential medium with D-valine substituted for L-valine. The relative ease with which this cell type can be isolated, cultured, and manipulated in vitro should encourage its application as a model of the respiratory epithelium.     

Comparison of proteins synthesized by polarized caprine oviductal epithelial cells and oviductal explants in vitro

Our objectives were to compare proteins secreted by caprine oviductal explants and oviductal epithelial (OE) cells in vitro. Oviducts were collected from goats on Days 1 (n=5) and 5 (n=5) of the estrous cycle. Radiolabeled secretory proteins from tissue segments and cell cultures were visualized using SDS-PAGE and fluorography. After culture, media from ampulla oviduct segments collected on Days 1 and 5 of the estrous cycle contained an acidic 97 kDa protein, which was greatly reduced in culture medium obtained from infundibulum and isthmus oviduct segments. A complex of low molecular weight proteins (14-26 kDa) could be modulated by estradiol when OE cells were cultured on plastic. This complex was constitutively expressed when OE cells were cultured on Matrigel-coated filters. Polarized OE cells were also capable of compartment-specific secretion of [L-(35)S]-methionine-labeled proteins. A 45 kDa acidic protein was predominantly secreted into the apical compartment while a 66 kDa acidic protein was preferentially localized in the basal compartment. Proteins secreted by OE cells were similar to proteins secreted by tissue segments in vitro. Therefore, under well-defined culture conditions OE cells may be useful in enhancing in vitro fertilization or early embryonic development.     

Epithelial cells in culture: injured or differentiated cells?

Isolation of epithelial cells for cell culture is based on destruction of epithelial integrity. The consequences are manifold: cell polarity and specific cell functions are lost; cells acquire non‐epithelial characteristics and start to proliferate. This situation may also occur in situ when parts of the epithelium are lost, either by apoptosis or necrosis by organ or tissue injury. During recovery from this injury, surviving epithelial cells proliferate and may restore epithelial integrity and finally re‐differentiate into functional epithelial cells. In vitro, this re‐differentiation is mostly not complete due to sub‐optimal culture conditions. Therefore cultured epithelial cells resemble wounded or injured epithelia rather than healthy and well differentiated epithelia. The value of an in vitro cell model is the extent to which it helps to understand the function of the cells in situ. A variety of parameters influence the state of differentiation of cultured cells in vitro. Although each of these parameters had been studied, the picture how they co‐ordinately influence the state of differentiation of epithelial cells in vitro is incomplete. Therefore we discuss the influence of the isolation method and cell culture on epithelial cells, and outline strategies to achieve highly differentiated epithelial cells for the use as an in vitro model.     

Establishment of a primary culture model of mouse uterine and vaginal stroma for studying in vitro estrogen effects

Effects of 17beta-estradiol (E2) on uterine and vaginal epithelial cell proliferation could be mediated by stromal cell-derived paracrine factors. To study the epithelial-stromal interactions in mice, an in vitro model of uterine and vaginal stromal cells of immature mice is essential. Therefore, we established a primary culture model of stromal cells both from uterus and vagina and examined the effect of E2 on proliferation of cultured stromal cells. We found that E2 stimulated proliferation of stromal cells from both organs in vitro, showing an increase in the number of cells and the percentage of 5-bromo-2'-deoxyuridine (BrdU)-labeled cells. Interestingly, vaginal stromal cells responded to lower E2 than uterine stromal cells in proliferation (10(-12) M vs. 10(-8) M) and BrdU labeling (10(-14) - 10(-10) M vs. 10(-10) - 10(-6) M). To examine the effect of E2 in vivo, cells were grafted into the subrenal capsule of the host mice and grown for 2 weeks. The BrdU labeling in cultured stromal cells was increased by E2 in vivo. To examine the effect of cultured stromal cells on epithelial cell proliferation, uterine and vaginal epithelium of adult mice were separated, recombined with the cultured stromal cells, and grafted under the renal capsule of hosts for 3 weeks. Epithelial cells recombined with cultured stromal cells showed simple columnar morphology in uterine grafts and stratified and keratinized morphology in vaginal grafts under the influence of the hormonal environment of the hosts. The BrdU labeling in epithelial cells was increased by E2, suggesting that cultured stromal cells can stimulate epithelial cell proliferation. In conclusion, we established a primary culture model of uterine and vaginal stromal cells, which can be mitogenically stimulated by E2 in vitro and in vivo after being grafted under the renal capsule. This culture system will be useful for investigating the underlying molecular mechanisms of uterine and vaginal epithelial-stromal interactions.     

Isolation and culture of hair cell progenitors from postnatal rat cochleae

Cochlear hair cells are a terminally differentiated cell population that is crucial for hearing. Although recent work suggests that there are hair cell progenitors in postnatal mammalian cochleae, isolation and culture of pure hair cell progenitors from a well-defined cochlear area have not been reported. Here we present an experimental method that allows isolation and culture of hair cell progenitors from postnatal rat cochleae. These progenitor cells are isolated from the lesser epithelial ridge (LER, or outer spiral sulcus cell) area of pre-plated neonatal rat cochlear segments. They express the same markers as LER cells in vivo, including ZO1, Islet1, Hes1, and Hes5. When these cells are induced to express Hath1, they show the potential to differentiate into hair cell-like cells. Interestingly, these cells can be lifted from monolayer cultures and maintained in aggregate cultures in which spheres can be formed. Hair cell progenitors in the spheres display their proliferating capability and express only epithelial markers. Furthermore, when these spheres are mixed with dissociated mesenchymal cells prepared from postnatal rat utricular whole mounts, and replated onto a collagen substratum, the epithelial progenitor cells are able to differentiate into cells expressing markers of hair cells and supporting cells in epithelial islands, which mirrors the inner ear sensory epithelium in vivo. Successful isolation and culture of hair cell progenitors from the mammalian cochlea will facilitate studies on gene expression profiling and mechanism of differentiation/regeneration of hair cells, which are crucial for repairing hearing loss.     

Temporal and spatial sequence expression of cytokeratin K19 in cultured human keratinocyte

The unique cytokeratin K19 specifically expresses in simple epithelial cells, basal cells of non-keratinized stratified squamous epithelium, epidermal cells during the embryonic stage and squamous carcinoma cells, but it is not expressed in adult epidermis. Interestingly, when epidermal cells are cultured in vitro, K19 is re-expressed in the supra-basal layer. K19 expression was used as a marker for epidermal cell growth and differentiation. In order to clarify the temporal and spatial sequential expression in cultured keratinocyte, two-stage human keratinocyte culture systems were used to examine K19 expression in keratinocytes in a proliferation and differentiation stages through immunoblotting and immunohistochemistry assay. According to our results, K19 was not expressed in cultured human keratinocytes in the proliferation stage but was re-expressed in keratinocytes three days after the cultured medium was changed to a differentiation medium. Immunohistochemical observation revealed that K19 was persistently expressed in the supra-basal layer of cultured keratinocytes during first three weeks of culturing, but none was detectable in the basal cell layer. When keratinocytes were cultured with an "inserted cultured dish," K19 was persistently expressed in all layers of keratinocytes nourished by medium both from an inner chamber and an outer chamber. The different expression of K19 in these two different culture systems seemed to indicate that down regulation of K19 expression in keratinocyte was related to the direction of medium supply.     

Histochemical identification of cultured cells from human endometrium

Histochemical techniques have been applied to the identification of cell types cultured from human endometrium. Previous work from this laboratory characterized two principal cell types found in cultures of endometrium: a mature epithelial cell and another cell which was classified as the endometrial stromal cell based on light and electron microscopy. In this report we compare the histochemical staining of endometrial tissue in frozen sections to that of cultured cells. These results confirm the epithelial and stromal nature of the respective cell types. Several markers were found that could distinguish between cells of epithelial and stromal origin. The enzymes alkaline phosphatase, gamma-glutamyltranspeptidase, peroxidase, and beta-glucuronidase were localized in glandular and surface epithelia in frozen sections and in colonies of epithelial cells in culture. Stroma in frozen sections and cultured stromal cells contained leucine aminopeptidase and fibronectin. Epithelia in sections and in culture could also be distinguished from cells of stromal origin by preferential binding of lotus and peanut lectin. Several other markers were found in both endometrial epithelium and stroma.     

Bovine oviductal epithelial cells: their cell culture and applications in studies for reproductive biology

Epithelial cells of the mammalian oviduct play an important role in reproductive and developmental events that occur there. Oviductal epithelial cells from several mammalian species can be isolated and cultured in serum or serum-free medium in vitro and cell culture of bovine oviductal epithelial cells (BOEC) has been described by many investigators. Cultured BOEC show a wide variety of secretory activities and these secretory factors may influence early embryonic development or sperm function. Monolayer cultures of BOEC have been widely used for in vitro co-culture of bovine preimplantation embryos. The use of BOEC co-culture systems has improved embryonic development in nearly all the studies conducted. In addition, interaction of bovine spermatozoa with BOEC, in a similar manner to that observed for spermatozoa in vivo, induced specific changes in sperm capacitation and consequently improved the fertilizing capacity of bovine spermatozoa in vitro. Thus co-culture systems with BOEC may not only offer an excellent model for studying the mechanisms of capacitation and acrosome reaction of bovine spermatozoa but also provide a useful tool for the improvement of embryo development in vitro.     

Factors affecting the differentiation of epithelial transport and responsiveness to hormones

Under standard culture conditions, epithelial cells grow with their basal surface attached to the culture dish and their apical surface facing the medium. Morphological and functional markers are located in the appropriate plasma membrane, and transepithelial transport occurs in a variety of cultured epithelia. As a result of the polarity of the cells and the presence of tight junctions between cells, on standard tissue culture dishes there is restricted access of growth medium to the basolateral surface of the epithelium, which is the surface at which nutrient exchange normally occurs. Greater differentiation of epithelial cultures can be achieved by growing primary cultures or continuous cell lines on permeable surfaces such as porous bottom cultures dishes in which the porous bottom is formed by a filter or membrane of collagen, or on floating collagen gels. In many cultures, differentiation varies with the time after the culture was seeded. Certain chemicals that accelerate differentiation in nonepithelial cells also accelerate the differentiation of epithelial cultures. Ultimately, defined media and specific substrates for cell attachment should lead to further differentiation of epithelia in culture.     

牦牛输卵管上皮细胞分离培养和纯化鉴定

为建立牦牛输卵管上皮细胞原代培养及纯化方法,通过选取牦牛输卵管,运用机械刮取法和0.25%胰蛋白酶消化两种方法分离上皮细胞进行体外培养。对不同分离方法的培养效果比较,培养细胞进行形态学观察与传代培养、MTT比色检测细胞活力并制定生长曲线,原代及传代上皮细胞的免疫组织化学鉴定,冷冻解冻后经台盼蓝排斥试验检测活细胞数。结果表明该试验分离出的原代细胞,纯化后传代培养,经鉴定为牦牛输卵管上皮细胞,培养的细胞生长状况良好,建立了一套牦牛输卵管上皮细胞分离培养及纯化鉴定的方法。     

Co-culture of ovine eggs with oviductal cells and trophoblastic vesicles

Three experiments were conducted to determine whether coculture of early sheep eggs with oviductal cells would improve the ability of eggs to survive in culture. Eggs recovered from superovulated ewes were cultured in Ham's F-10 medium supplemented with 10% fetal calf serum (F10FCS) at 37.5 degrees C in 95% air:5% CO(2). In Experiment 1, eggs with one to eight cells were either transferred into recipient ewes immediately after collection or were cultured for 24 h in 5 ml Ham's F10 medium supplemented with 10% fetal calf serum (F10FCS), 5 ml F10FCS on a confluent monolayer of oviductal cells; in 25 ml of fresh F10FCS; or in 25 ml of F10FCS removed cultures of oviductal cells, 25 mul of fresh F10FCS or 25 mul of F10FCS removed from cultures of oviductal cells. After 24 h, the cultured eggs were transferred to recipient ewes synchronous with donors and subsequently recovered at necropsy on Day 8 post estrus. Coculture of sheep eggs with oviductal cells improved (P < 0.05) the development of transferred eggs compared to culture in F10FCS alone. In Experiment 2, eggs recovered from superovulated ewes on Days 3 to 6 after estrus had undergone 1.8 cleavages by Day 3 and 4.1 cleavages by Day 6. In Experiment 3, single-cell eggs were cultured for 3 d in 5 ml F10FCS, cocultured with ovine trophoblastic vesicles or cultured on a confluent monolayer of oviductal cells. Coculture of eggs in F10FCS on a monolayer of oviductal cells supported in vitro egg cleavage to a greater degree than did F10FCS alone or F10FCS with trophoblastic vesicles (P < 0.05). In Experiment 4, single-cell eggs were cultured for 3 d then transferred to recipients. Eggs were cultured in 5 ml F10FCS on confluent monolayers of oviductal cells from luteal or estrous ewes or on cells that had been frozen after recovery from a culture of oviductal cells. After culture, the eggs were transferred to oviducts of recipients and recovered 3 d later at necropsy. Coculture of eggs for 72 h with oviductal cell monolayers did not increase the in vitro, or subsequent in vivo, cleavage rate regardless of the type of oviductal cells.     

Differentiated structure and function of primary cultures of monkey oviductal epithelium

Summary We have established well-differentiated, polarized cultures of monkey oviductal epithelium. Oviductal epithelial cells were isolated by protease digestion and plated on collagen-coated, porous cell culture inserts. About 5 d after plating, cells developed detectable transepithelial electrical resistance of up to 2000 Ω.cm² (an index of tight junction formation) and transepithelial voltages of up to 20 mV (an index of vectorial transepithelial ion transport). Measurements of short-circuit current in Ussing chambers indicated that active secretion of Cl was the major transepithelial active ion transport process, and that this was stimulated by elevation of either cAMP or Ca. Furthermore, estimates of the volume of mucosal liquid were consistent with Cl secretion mediating fluid secretion. Various microscopical methods showed that the cultures were densely ciliated and contained mature secretory cells. Transport across the oviductal epithelium determines the composition of the oviductal fluid, and the study of the relevant transport processes will be greatly enhanced by well-differentiated cultures of oviductal epithelium of the kind established here.