Overview of the different methods used in the primary culture of oral mucosa cells.

The culture of primary cells in vitro has enabled to gain knowledge in the field of cell biology, disease mechanisms and to offer great potential in drug testing. To date, two main techniques of isolating and culturing oral mucosal cells, the direct explant method and the enzymatic method, dominate the literature and practice. In the present study, both techniques are discussed in detail, comparing the advantages and disadvantages of the two approaches in setting up a primary culture of oral mucosal cell. The direct explant technique is well-established and has been commonly used for the past 20-30 years. Although the method of setting up the cultures did not show much variations in the methodology described by authors, the culturing conditions varied according to the aims of the projects.

Gene expression regulating lipopolysaccharide and lipid metabolic processes in porcine oral mucosal cells in long-term primary in vitro culture.

Lipids are an alternative energy source for cells and provide structural integrity in cell membrane and their metabolism is regulated with the use of different pathways, such as integrin signalling, oxidative stress, mechanical stress, and pH changes. All of those processes take place in the oral mucosa which is subject to different environmental impacts. In this study, porcine buccal pouch mucosal cells (pBPMCs) were used during long-term primary in vitro culture. The cultured cells were collected at 7, 15 and 30 days of IVC and subsequently transferred to RNA isolation. In the results of the following microarray analysis, we analyzed the genes detected, belonging to ontology groups, such as "cellular lipid metabolic process", "response to lipid" and "response to lipopolysaccharides. All of the genes involved in these ontological groups were expressed at higher levels at 7 days of IVC and substantially decreased in expression at days 15 and 30 of primary culture. We observed new genes, which may be recognized as markers in regulation of lipid metabolism in mucosal cells in vitro. The results suggested that the biochemical mechanism-involved lipids were accompanied by increased enzymatic activation and synthesis of crucial growth factors reaching high activity at day 7 of culture, which is also well documented as a stage of tissue regeneration period within oral mucosa. Therefore, this "biochemical fingerprint" may be an additional checkpoint of the integrity, resistance and easy adaptability of oral tissues, which are important conditions of success in tissue engineering and grafting for tissue reconstruction.

The p75 neurotrophin receptor in cells of oral mucosal epithelium.

The p75 neurotrophin receptor (p75NTR) can play different roles in cells. This protein can on the one hand act in the regulation of cell growth and survival, while being an apoptosis inducing factor in different contexts. p75NTR regulates cell cycle not only in nerve cells but also in epithelial oral mucosal cells. In the former, neurotrophin-p75NTR signaling affects cell growth and survival. Recent studies showed that p75NTR is expressed in basal cells of oral mucosal epithelium and can be used as one of the markers of epithelial stem/progenitor cells. This role of p75NTR can be utilised in aspects such as tissue engineering and gene therapy. One of the examples of clinical use of cultivated oral mucosal cells is ocular surface reconstruction. p75NTR can be a significant marker of stem cells in studies of epithelial tissues, especially when the cells will exhibit other specific markers, such as CK13, CK14 and PCNA..

Balance between epithelial and stromal marker expression and distribution in primary culture model of porcine endometrium during real-time cell proliferation..

The similarity between humans and pigs, when it comes to tissue morphology, makes Sus scrofa not only a good research model, but also a potential source of cells for tissue engineering. Cell samples obtained from the pig donor, could be influenced in vitro, in order to become a source of tissue material for xenotransplantation, reconstructive and regenerative medicine. Significant amounts of data point to especially major similarities in pig and human reproductive systems. Because of that, particular scientific focus is centered on research concerning porcine COCs, theca and granulosa cells in primary cultures. One of the aspects of the reproductive process, that is still largely undiscovered, is the interaction between preimplantation blastocyst and maternal uterine tissues. In this study, we used molecular analysis techniques, such as RT-qPCR and immunocytochemistry, to analyze the expression and distribution of cytokeratin 18 and panCytokeratins 8, 18 and 19 and vimentin in porcine luminal endometrial epithelial cells, coupled with analysis of their behavior in RTCA. The results have confirmed the presence of epithelial, as well as stromal cell markers in the cells, varying in levels at different stages of culture. They have also given insight into the modes of proliferation and differentiation of studied cells in in vitro culture, as well as providing additional proof for the possible mesenchymal transdifferentiation of epithelial cells.

Genes involved in regulation of cellular metabolic processes, signaling and adhesion are the markers of porcine buccal pouch mucosal cells long-term primary cultured in vitro.

Extraordinary abilities for continuous proliferation and differentiation, associated with constant renewal triggered by stimulation from the mastication process, together with the relative lack of aesthetic complications associated with post-surgery healing, have highlighted buccal pouch mucosa as a potential source of explants that could be used in transplantation and tissue engineering. Additionally, this tissue plays a major role in the oral drug delivery process, which brings special interest to its molecular properties in the context of new drug development. There is therefore a need to analyse the exact mechanisms of oral mucosa functioning, especially when it comes to the processes that are associated with the potential clinical applications. In this study we analysed a complete transcriptome of long-term in vitro cultures of porcine buccal pouch oral mucosa cells. Using a microarray approach, we focused on genes associated with cellular metabolic processes, signalling and adhesion, from 4 gene ontology groups: "Positive regulation of cellular component movement", "Positive regulation of cellular process", "Positive regulation of intracellular signal transduction" and "Single organism cell adhesion". Nineteen genes (CCL8, CXCL2, PLK2, DUSP5, PTGS2, LIF, CCL2, ATP1B1, REL, ITGB3, SCARB1, UGCG, PDPN, LYN, ETS1, FCER1G, TGFB1, RFC4, LMO2) with fold changes higher than |2| and p value Extraordinary abilities for continuous proliferation and differentiation, associated with constant renewal triggered by stimulation from the mastication process, together with the relative lack of aesthetic complications associated with post-surgery healing, have highlighted buccal pouch mucosa as a potential source of explants that could be used in transplantation and tissue engineering. Additionally, this tissue plays a major role in the oral drug delivery process, which brings special interest to its molecular properties in the context of new drug development. There is therefore a need to analyse the exact mechanisms of oral mucosa functioning, especially when it comes to the processes that are associated with the potential clinical applications. In this study we analysed a complete transcriptome of long-term in vitro cultures of porcine buccal pouch oral mucosa cells. Using a microarray approach, we focused on genes associated with cellular metabolic processes, signalling and adhesion, from 4 gene ontology groups: "Positive regulation of cellular component movement", "Positive regulation of cellular process", "Positive regulation of intracellular signal transduction" and "Single organism cell adhesion". Nineteen genes (CCL8, CXCL2, PLK2, DUSP5, PTGS2, LIF, CCL2, ATP1B1, REL, ITGB3, SCARB1, UGCG, PDPN, LYN, ETS1, FCER1G, TGFB1, RFC4, LMO2) with fold changes higher than |2| and p value less than 0.05 were identified, described in context and analysed. While the study needs much further validation to become applicable in a clinical environment, it yields valuable information about the transcriptomic basis of oral mucosal cell functioning in vitro, that might serve as a reference for further research, aiming to apply this knowledge in clinical situations.0.05 were identified, described in context and analysed. While the study needs much further validation to become applicable in a clinical environment, it yields valuable information about the transcriptomic basis of oral mucosal cell functioning in vitro, that might serve as a reference for further research, aiming to apply this knowledge in clinical situations.

Enzyme linked receptor protein signaling pathway is one of the ontology groups that are highly up-regulated in porcine oocytes before in vitro maturation.

Before being able to fully participate in the processes associated with its function as a female gamete, the oocyte needs to undergo a range of changes to achieve its mature form. These morphological, biochemical and metabolomic processes are induced by the somatic tissues surrounding the oocyte, through the expression of specific transcription and growth factors. The maturation of the oocyte is highly important for the proceedings that lead to successful fertilization, early embryonic development and implantation. Domestic pigs were used as models for our study, with the cumulus-oocyte complexes obtained from the ovaries that were recovered at slaughter. After shedding of the cumulus, oocytes were assessed with BCB test, with the viable ones chosen to undergo in vitro maturation. With the use of expression microarrays, we analyzed gene expression before and after IVM and detected major changes in both genes that were proven to be associated with oocyte maturation before (FOS, VEGFA, CHRDL1, TGFBR3, FST, INSR, ID1, TXNIP, SMAD4, MAP3K1, EIF2AK3 and KIT) and genes not previously linked with reproduction associated processes (MYO1E, PHIP, KLF10 and SHOC2). All the genes were briefly described, with consideration of possible involvement of the newly discovered elements of the transcriptome in the process of oocyte maturation.

Expression of connexins in porcine buccal pouch mucosa cells during real-time long-term cell proliferation in vitro: a primary culture approach.

In this study we investigated the expression of connexins Cx36, Cx37, Cx40, Cx43, and Cx45 mRNAs during real-time cellular proliferation in vitro. The oral mucosa cells were isolated from 80 pubertal crossbred Landrace gilts. The cells were transferred into primary in vitro culture (IVC) and cultured for 30 days. The cells were collected to RNA isolation after 7, 15 and 30 days of IVC and were checked for their real-time proliferative status using real-time cell analysis (RTCA). We found an increased expression of Cx43 mRNA after 30 days of IVC as compared to control (P<0.05). The expression level of Cx36 was significantly decreased after 30 days. The expression of Cx37, Cx40 and Cx45 mRNAs was not changed. The expression of Cx43 was statistically increased when compared to Cx40, Cx37, Cx45 and Cx36 (P<0.001, for all time periods, respectively). We confirmed the expression of selected connexins in porcine buccal mucosa cells during their long-term primary IVC, which suggests the existence of functional gap junction connections (GJCs) communication network between these cells. We also confirmed the observations of other authors that Cx43 plays a substantial role in GJC structure. However, the increased expression of Cx43 in buccal mucosa cells, accompanied with their proliferation during real-time primary culture, is presented, to our knowledge, for the first time.

Expression of genes responsible for cell morphogenesis involved in differentiation in porcine buccal pouch mucosal cells during long-term primary culture and real-time proliferation in vitro.

Recently, using experimental animal model, we demonstrated that porcine buccal pouch mucosal cells reflect increased proliferation capability during primary cultivation in vitro. Although the histological structure and morphogenesis in oral cavity is well recognized, the molecular mechanisms which regulate this process still need further investigation. This study was aimed to analyze the molecular marker expression profile involved in morphogenesis and differentiation capacity of porcine buccal pouch mucosal cells during their long-term primary cultivation in vitro. The experiment was performed on buccal pouch mucosal cells isolated from 80 pubertal crossbred Landrace gilts. After collection, the cells were treated enzymatically and transferred into a primary in vitro culture (IVC) system and cultured for 30 days. The cells were collected for RNA isolation after 7, 15 and 30 days of IVC and were checked for their real-time proliferative status using the RTCA system. We found an increased expression of FN1 and SOX9 genes when calculated against ACTB after 7, and 30 days of IVC, (P less than 0.01, P less than 0.001, respectively). The CXCL12 mRNA was down-regulated after 7, 15 and 30 days of IVC, but not statistically significant. Similar expression profile was observed when calculated against HPRT, however, DAB2 was found to be higher expressed at day 15 of IVC, (P less than 0.05). The cell index measured during real-time cell proliferation was substantially increased between 96 h and 147h of IVC and reached the log phase. Since FN1 and SOX9 revealed significant increase of expression after long-term culture in vitro, it is suggested that expression of these differentiation and stemness genes is accompanied by cell proliferation. Moreover, FN1 and SOX9 might be recognized as new markers of buccal pouch mucosal cell proliferation and differentiation in pigs in in vitro primary culture model.

Expression of cell mitotic progression proteins and keratinocyte markers in porcine buccal pouch mucosal cells during short-term, real-time primary culture.

The porcine model is often used in clinical trials. The pig has many fundamental anatomic, physiological and nutritional similarities to humans. Additionally, the European Medicines Agency (EMA) demands the use large animals in clinical studies. Oral mucosa has received special attention due to its regenerative properties. Oral tissue is composed of several types of cells including fibroblasts and keratinocytes. The porcine oral mucosa/buccal pouch mucosa has a cellular structure with defined proliferation and differentiated capability. In this study, we investigated the expression pattern of porcine buccal pouch mucosal cell proliferation and differentiation markers such as Ki-67, proliferating cell nuclear antigen (PCNA), and involucrin. We observed a clear monolayer culture of spindle-shaped, porcine buccal pouch mucosal cells during 168 h of real-time in vitro culture. The RTCA assays revealed parametric and progressive increases in proliferation after 72 h of IVC. We found an altered proliferation index (PI) in the replicated groups of experiments except through the 144-168 h proliferation period. The RT-qPCR results demonstrated a significant increase in Ki-67 and PCNA expression after 48, 120, and 168 h of IVC as compared to other culture periods (P<0.001). The involucrin mRNA displayed increased expression after 168 h of IVC as compared to other periods. We observed a lack of PCR product at 24 h in the case of Ki-67 and both before IVC (0h) and after 24 h of IVC for PCNA mRNA. When we analyzed the three transcripts together, we found the highest expression of involucrin during each of the culture periods. It has been suggested that Ki-67, PCNA, and involucrin may be successfully used as markers of porcine buccal pouch mucosal cell proliferation and differentiation capability in vitro.

The origin, in vitro differentiation, and stemness specificity of progenitor cells.

Since the successful collection of the first progenitor stem cells (SCs), there has been an increased interest in these cells as a model for undiscovered and unlimited potential of differentiation and development. Additionally, it was shown that SC populations display an ability to form pluripotent and/or totipotent cell populations. It was found that human ovarian granulosa cells (GCs) maintain a large capacity for differentiation into several other cell lineages, such as chondrogenic, osteogenic, neurogenic, and adipogenic, particularly during long-term, in vitro culture. In these cases, the specific media supplements that promote various pathways of differentiation, such as leukemia-inhibiting factor (LIF) and/or FSH, are well recognized. However, these are only some examples of the differentiation possibilities of human SCs in vitro and other pathways still require further investigation. Many SC populations, which are directed to differentiate into specific cell types, are also successfully used in several human disease therapies, e.g. leukemia. Moreover, SCs are used for tissue scaffold construction in patients with respiratory and cardiovascular diseases. In this review, the most recent knowledge about the in vitro growth and differentiation capacity of SCs is presented. Furthermore, we discuss the possible worldwide application of SCs in advanced cell and tissue bioengineering. In conclusion, it is suggested that, in the future, SCs will be a basic strategy in human therapy, and their use will open new gates in regenerative and reconstructive medicine in the 21st century.

Molecular basis of growth, proliferation, and differentiation of mammalian follicular granulosa cells.

For normal folliculogenesis and oogenesis to occur many intrinsic and extrinsic factors are needed, i.e. positive feedback of hormone secretion and local ovarian-follicular growth factors distribution. During follicle formation, granulosa cells (GCs) change their morphology and physiological properties. The factors needed for GCs to differentiate within each layer are transforming growth factor beta (TGFB) and insulin-like growth factor (IGF), as well as the activation and modification of biochemical pathways involved in folliculogenesis. Physiological alterations occur when GC genes are characterized by several differences in their gene expression profile. Studies in recent years indicate a variety of processes involved in follicle morphology and biochemical remodeling during growth and development. It was demonstrated that IGFs play a central role in the differentiation of GCs both in vivo and in vitro. Moreover, the primary role of FSH and LH in the formation of the ovarian follicle, was also described. Our review article characterizes the most important pathways involved in the differentiation of GCs and the effect of various factors on gene expression in GCs during folliculogenesis.

The biomedical aspects of oral mucosal epithelial cell culture in mammals.

In recent years, there has been a growing interest in epithelial cell tissue culture, particularly oral mucosa and its application utilizing in vitro cell culture in medicine. This involves tests using animal models to better understand oral mucosa function, and the differences in its construction in various animal models. The use of buccal pouch mucosal cell culture provides insight into the processes of trans mucosal transport and regeneration of the oral epithelium. The processes associated with epithelium regeneration is the base for stem cell research and/or oral cancer investigation. These artificially cultured tissue equivalents are used in transplant surgery for the treatment of a variety of tissue dysfunctions, i.e. eye, esophagus, or urethra. In this review, the most recent results from studies carried out on in animal models, which may be applied in areas such as regenerative medicine and reconstructive surgery, were explored.

Differential expression and distribution of cytokeratins and vimentin in buccal pouch mucosal cells during real-time cell proliferation: research based on a porcine model.

In recent years, buccal pouch oral mucosa cells were used as a source of potential biological grafting material in advanced tissue engineering. However, there are several limitations in the process of graft fabrication: donor and recipient patient availability as well as an incomplete knowledge of in vitro procedures related to tissue surgical recovery, in vitro cell culture (IVC) and/or tissue processing in "human somatic cell therapy." Therefore, the animal model for oral mucosa grafting is still recognized as a source for xenografts and a useful model for biomedical research. In this study, the porcine buccal pouch oral mucosa cells were used in analysis of the stromalization/epithelialization process during short-term, in vitro real-time cell proliferation. We evaluated cytokeratin 18 (CK18), cytokeratin 8 + 18 + 19 (panCK), and vimentin (Vim) expression as epithelial and stromal cell markers, respectively. The porcine buccal pouch oral mucosa cells were cultured in vitro for 168 h, and the protein expression/ distribution was analyzed every 24 h during real-time cell proliferation. In our analysis of protein expression using fluorescence intensity (FI), followed by confocal microscopic observations, we found the highest expression of CK18 occurred after 24 h of IVC, panCK after 72 h, and Vim after 48 h of IVC, as compared to other cultivation periods. We also found a substantial increase in Vim expression (3-4 fold) as compared to CK18 and panCK, and all of the investigated proteins were distributed in the cellular cytoplasm. The lag phase of cell proliferation occurred during the first 24 h of IVC, whereas the log phase was observed between 24 h-120 h of IVC. Throughout 7 days of IVC, statistically significant differences were found in Cell Index (CI) of the analyzed cells. Increased Vim expression in buccal pouch oral mucosa cells, as compared to CK18 and panCK, suggested that the stromal cells substantially predominated during in vitro cell cultivation. This may be a result of significant specificity of porcine oral mucosa cells isolated from the buccal pouch.

Microfluidic versus molecular assays - different approaches in assessing oocyte developmental competence.

In recent years, molecular techniques have brought about new solutions that focus on the developmental capacity of female oocytes and reproductive performance in the mammalian species. The developmental potency is the ability of oocytes to reach the MII stage following the long stages of folliculo- and oogenesis. The main proteins involved in this process belong to the connexin (Cx) family, which are responsible for the formation of gap junction (GJC) connections between the female gamete and surrounding somatic cells. The Cx are involved in bi-directional transport of small molecules and are therefore responsible for correct oocyte-somatic cell nutrition, proliferation, and differentiation. However, the application of certain molecular techniques often leads to destabilization or destruction of the materials of interest, such as cells or whole tissues. Therefore, the applications of microfluidic methods, which are non-invasive and quantitative, give new opportunities to further this area of biomedical research. Microfluidic research is based on real-time experiments that allow for control and/ or observation of the results during each step. The purpose of this review is to present both positive and negative aspects of molecular-microfluidic methods while describing the role of connexins in oocyte developmental capacity.

The differentiation of mammalian ovarian granulosa cells – living in the shadow of cellular developmental capacity.

The mammalian cumulus-oocyte complex (COCs) promotes oocyte growth and development during long stages of folliculogenesis and oogenesis. Before ovulation, the follicle is formed by a variety of fully differentiated cell populations; cumulus cells (CCs) that tightly surround the female gamete, granulosa cells (GCs) and theca cells (TCs) which build the internal and external mass of the follicular wall. It is well documented that CCs surrounding the oocyte are necessary for resumption of meiosis and full maturation of the gamete. However, the role of the granulosa cells in acquisition of MII stage and/or full fertilization ability is not yet entirely known. In this article, we present an overview of mammalian oocytes and their relationship to the surrounding cumulus and granulosa cells. We also describe the processes of GCs differentiation and developmental capacity. Finally, we describe several markers of mammalian GCs, which could be used for positive identification of isolated cells. The developmental capacity of oocytes and surrounding somatic cells – a “fingerprint” of folliculogenesis and oogenesis.

Epithelialization and stromalization of porcine follicular granulosa cells during real-time proliferation - a primary cell culture approach.

The process of oocyte growth and development takes place during long stages of folliculogenesis and oogenesis. This is accompanied by biochemical and morphological changes, occurring from the preantral to antral stages during ovarian follicle differentiation. It is well known that the process of follicle growth is associated with morphological modifications of theca (TCs) and granulosa cells (GCs). However, the relationship between proliferation and/or differentiation of porcine GCs during long-term in vitro culture requires further investigation. Moreover, the expression of cytokeratins and vimentin in porcine GCs, in relation to real-time cell proliferation, has yet to be explored. Utilizing confocal microscopy, we analyzed cytokeratin 18 (CK18), cytokeratin 8 + 18 + 19 (panCK), and vimentin (Vim) expression, as well as their protein distribution, within GCs isolated from slaughtered ovarian follicles. The cells were cultured for 168 h with protein expression and cell proliferation index analyzed at 24-h intervals. We found the highest expression of CK18, panCK, and Vim occurred at 120 h of in vitro culture (IVC) as compared with other experimental time intervals. All of the investigated proteins displayed cytoplasmic distribution. Analysis of real-time cell proliferation revealed an increased cell index after the first 24 h of IVC. Additionally, during each period between 24-168 h of IVC, a significant difference in the proliferation profile, expressed as the cell index, was also observed. We concluded that higher expression of vimentin at 120 h of in vitro proliferation might explain the culmination of the stromalization process associated with growth and domination of stromal cells in GC culture. Cytokeratin expression within GC cytoplasm confirms the presence of epithelial cells as well as epithelial-related GC development during IVC. Moreover, expression of both cytokeratins and vimentin during short-term culture suggests that the process of GC proliferation is also highly associated with porcine ovarian follicular granulosa cell differentiation in vitro.

Association between expression of cumulus expansion markers and real-time proliferation of porcine follicular granulosa cells in a primary cell culture model.

Folliculogenesis is a compound process that involves both ovarian follicle growth and oocyte development, which is tightly attached to the follicular wall. During this process, cells that form the follicle structure undergo substantial morphological and molecular modifications that finally lead to differentiation and specialization of ovarian follicular cells. The differentiation of ovarian cells encompasses formation of follicle, which is composed of theca (TCs), mural granulosa (GCs), and cumulus cells (CCs). It was previously hypothesized that GCs and CCs represent undifferentiated and highly specialized follicular cells, respectively, which may have similar primordial cell origins. In this study, we investigated the expression pattern of cumulus expansion markers such as COX2, HAS2, PTX3, and TSG6 in porcine GCs during short-term, in vitro culture. We hypothesized that these genes may display an important function in GCs in relation to cellular real-time proliferation. The expression pattern of COX2, HAS2, PTX3, and TSG6 was evaluated after using RT-qPCR in relation to confocal microscopy observations of protein expression and distribution during real-time proliferation of porcine follicular GCs. The COX2 and HAS2 mRNAs were highly expressed after 120 h of in vitro culture (IVC), whereas PTX3 and TSG6 mRNAs were increased during the first 24-48 h of IVC (P less than 0.001, P less than 0.01). Conversely, all of the encoded proteins were highly expressed after 144-168 h of IVC as compared to other culture periods (P less than 0.001, P less than 0.01). When analyzing the realtime proliferation of GCs in vitro, we observed a logarithmic increase of cell proliferation between 0 h and 120 h of IVC. However, after 120-168 h of IVC, the cells reached the lag phase of proliferation. Since it is well accepted that porcine GCs undergo luteinization shortly after 24-48 h of IVC, the expression pattern of investigated genes indicated that Cox2 and Has2 are independent from the LH surge, but their increased levels may be upregulated by cell proliferation in vitro. Moreover, higher expression of PTX3 and TSG6 during first 24 h and/or 48 h of IVC suggested that their levels are accompanied by porcine GCs luteinization process.

Association between progesterone and estradiol-17beta treatment and protein expression of pgr and PGRMC1 in porcine luminal epithelial cells: a real-time cell proliferation approach.

The correct functionality (sensitivity and receptivity) of endometrial tissue is regulated by paracrine and endocrine pathways that activate several mediators or metabolic pathways and gene cascades. This study aimed to investigate the influence of E2 and P4 on progesterone receptor (PGR) and progesterone receptor membrane component 1 (PGRMC1) protein expression in porcine luminal epithelial cells and their influence on the proliferation of these cells in real-time. Surface uterine luminal epithelial cells were removed using sterile surgical blades from uterine horns of ten crossbred anestrus gilts. Following treatment with collagenase I, cells were separated and transferred into 48-well E-Plates for use in a realtime cell analyzer (RTCA). The luminal epithelial cells were cultured in vitro (IVC) in standard DMEM cell culture medium and incubated with E2 (10 pg/ml, 40 pg/ml, 500 pg/ml) and P4 (10 ng/ml, 40 ng/ ml, 500 ng/ml). The cell proliferation index was analyzed after 0-240 h, 0-120 h, 120-240 h. After using the RTCA analysis we found increased proliferation of luminal epithelial cells after treatment of low doses of P4 (10 and 40 ng/ml), (P < 0.001). Higher doses of P4 led to decrease of proliferation (P < 0.001). Conversely, higher doses of E2 (500 pg/ml) increased the proliferation index as compared to low doses (10 pg/ml) and control (P < 0.001). Confocal microscopic observations revealed that higher concentrations of E2 upregulate the expression of both PGR and PGRMC1. Additionally, P4 used in lower concentrations stimulated the expression of these receptors, too. Our study presents a new influence of E2 and P4 on the expression of PGR and PGRMC1 and on the real-time proliferation of porcine luminal epithelial cells. The relationship between PGR or PGRMC1 expression and the proliferation of luminal epithelial cells may be influenced (up- or down regulated) by E2 or P4 in a steroid type- and dose-dependent manner.