[Cell cultures]. / Tkánové kultury.

Cell or tissue cultures (both terms are interchangeable) represent a complex process by which eukaryotic cells are maintained in vitro outside their natural environment. They have a broad usage covering not only scientific field but also diagnostic one since they represent the most important way of monoclonal antibodies production which are used for both diagnostic and therapeutic purposes. Cell cultures are also used as a "cultivation medium" in virology and for establishing proliferating cells in cytodiagnostics. They are well-established and easy-to-handle models in the area of research, e.g. as a precious source of nucleic acids or proteins. This paper briefly summarizes their importance and methods as well as the pitfalls of the cultivation and new trends in this field.

HIV-positive Ukrainian refugees in the Czech Republic.

OBJECTIVE: Over 480 000 Ukrainian refugees have arrived in the Czech Republic since the Russian invasion of Ukraine in 2022, including over 500 people with HIV. This study describes the demographics, characteristics, and management of Ukrainian refugees with HIV in the Czech Republic. DESIGN: Retrospective, observational, noninterventional study. METHODS: Ukrainian nationals registering at HIV centers in the Czech Republic with war refugee status were included. Data were collected from medical records between 1 March and 31 July 2022. The study was registered with the Czech State Institute for Drug Control, ID number 2301200000. RESULTS: Four hundred and eighty-two patients were included in the study. Most patients were female (69.5%; n  = 335/482) with well-controlled HIV. The median [interquartile range] CD4 + cell count was 597 [397] cells/µl of blood, and 79.3% ( n  = 361/455) of patients had HIV RNA <40 copies/ml. Coinfections of hepatitis C virus, hepatitis B virus, and/or tuberculosis were reported for 17.4% ( n  = 78/449), 9% ( n  = 40/446) and 1.3% ( n  = 6/446) of patients, respectively. In Ukraine, 85.7% ( n  = 384/448) of patients had been receiving an integrase strand transfer inhibitor-based regimen and most (69.7%; n  = 310/445) did not switch therapy upon arrival in the Czech Republic. CONCLUSION: Migration from Ukraine is changing the characteristics of HIV epidemiology in the Czech Republic. Ukrainian refugees with HIV have been provided with a high standard of medical care in the Czech Republic. Improved coordination between medical services within the Czech Republic and between countries in the European Union is necessary to optimize patient care.

Impact of histone deacetylase inhibitor valproic acid on the anticancer effect of etoposide on neuroblastoma cells.

OBJECTIVES: Etoposide (Vepesid, VP-16), an inhibitor of topoisomerase II, is a chemotherapeutic drug commonly used for treatment of different types of malignant diseases. By inhibiting the topoisomerase II enzyme activity in cancer cells, this drug leads to DNA damage and subsequently to cell death. In this study, we investigated the effect of this anticancer drug alone and in combination with a histone deacetylase (HDAC) inhibitor, valproic acid (VPA), on a human UKF-NB-4 neuroblastoma cell line. METHODS: The effects of etoposide and VPA on UKF-NB-4 cells were tested under the normoxic and also the hypoxic (1% O2) cultivation conditions. The cytotoxicity of etoposide and VPA to a UKF-NB-4 neuroblastoma cell line was evaluated with MTT assay. Apoptosis of the cells was analyzed by flow cytometry using an Annexin V and propidium iodide binding method. The effect of etoposide and VPA on the cell cycle distribution was determined by flow cytometric analysis using propidium iodide staining. RESULTS: The results of the study demonstrate that UKF-NB-4 neuroblastoma cells are sensitive both to etoposide and to VPA. They also indicate that the impact of VPA on cytotoxicity of etoposide in these tumor cells varies depending on the sequence of cultivation of the cells with the drugs. As a suitable sequence of cultivation, with a high rate of suppression of neuroblastoma cell growth was found the preincubation of the cells with etoposide, which was followed by their cultivation with VPA. In contrast, the reversed combination (preincubation of the cells with VPA before their treating with etoposide) did not give any increase in etoposide cytotoxicity. The effect of such combined treatment can be explained by measuring the cell cycle distribution, which shows that both etoposide and VPA change the cell cycle phase distribution. CONCLUSION: Etoposide and VPA were found as cycle phase specific drugs that are cytotoxic to human UKF-NB-4 neuroblastoma cells used either as single drugs or both together. However, whereas VPA might sensitize the cells to etoposide, inappropriate sequence of cultivation of the cells with VPA can decrease the etoposide cytotoxic efficacy. The results found here warrant further studies of combined treatment of neuroblastoma cells with etoposide with HDAC inhibitors and may help in the design of new protocols geared to the treatment of high risk neuroblastomas.

Stromal Vascular Fraction and its Role in the Management of Alopecia: A Review.

Adipose cells organized in small clusters under the reticular dermis closely interact with hair follicular cells and regulate the hair cycle. Intradermal adipocyte progenitor cells are activated toward the end of the telogen phase to proliferate and differentiate into mature adipocytes. These cells, surrounding the hair follicles, secrete signaling molecules that control the progression of the hair cycle. Diseases associated with defects in adipocyte homeostasis, such as lipodystrophy and focal dermal hypoplasia, lead to alopecia. In this review, we discuss the potential influence of stromal vascular fraction from adipose tissue in the management of alopecia as well as its involvement in preclinical and clinical trials.

Clinically Relevant Solution for the Hypothermic Storage and Transportation of Human Multipotent Mesenchymal Stromal Cells.

The wide use of human multipotent mesenchymal stromal cells (MSCs) in clinical trials requires a full-scale safety and identity evaluation of the cellular product and subsequent transportation between research/medical centres. This necessitates the prolonged hypothermic storage of cells prior to application. The development of new, nontoxic, and efficient media, providing high viability and well-preserved therapeutic properties of MSCs during hypothermic storage, is highly relevant for a successful clinical outcome. In this study, a simple and effective trehalose-based solution was developed for the hypothermic storage of human bone marrow MSC suspensions for further clinical applications. Human bone marrow MSCs were stored at 4°C for 24, 48, and 72 hrs in the developed buffered trehalose solution and compared to several research and clinical grade media: Plasma-Lyte® 148, HypoThermosol® FRS, and Ringer's solution. After the storage, the preservation of viability, identity, and therapeutically associated properties of MSCs were assessed. The hypothermic storage of MSCs in the new buffered trehalose solution provided significantly higher MSC recovery rates and ability of cells for attachment and further proliferation, compared to Plasma-Lyte® 148 and Ringer's solution, and was comparable to research-grade HypoThermosol® FRS. There were no differences in the immunophenotype, osteogenic, and adipogenic differentiation and the immunomodulatory properties of MSCs after 72 hrs of cold storage in these solutions. The obtained results together with the confirmed therapeutic properties of trehalose previously described provide sufficient evidence that the developed trehalose medium can be applied as a low-cost and efficient solution for the hypothermic storage of MSC suspensions, with a high potential for translation into clinical practice.

Valproic Acid Increases CD133 Positive Cells that Show Low Sensitivity to Cytostatics in Neuroblastoma.

Valproic acid (VPA) is a well-known antiepileptic drug that exhibits antitumor activities through its action as a histone deacetylase inhibitor. CD133 is considered to be a cancer stem cell marker in several tumors including neuroblastoma. CD133 transcription is strictly regulated by epigenetic modifications. We evaluated the epigenetic effects of treatment with 1mM VPA and its influence on the expression of CD133 in four human neuroblastoma cell lines. Chemoresistance and cell cycle of CD133+ and CD133- populations were examined by flow cytometry. We performed bisulfite conversion followed by methylation-sensitive high resolution melting analysis to assess the methylation status of CD133 promoters P1 and P3. Our results revealed that VPA induced CD133 expression that was associated with increased acetylation of histones H3 and H4. On treatment with VPA and cytostatics, CD133+ cells were mainly detected in the S and G2/M phases of the cell cycle and they showed less activated caspase-3 compared to CD133- cells. UKF-NB-3 neuroblastoma cells which express CD133 displayed higher colony and neurosphere formation capacities when treated with VPA, unlike IMR-32 which lacks for CD133 protein. Induction of CD133 in UKF-NB-3 was associated with increased expression of phosphorylated Akt and pluripotency transcription factors Nanog, Oct-4 and Sox2. VPA did not induce CD133 expression in cell lines with methylated P1 and P3 promoters, where the CD133 protein was not detected. Applying the demethylating agent 5-aza-2'-deoxycytidine to the cell lines with methylated promoters resulted in CD133 re-expression that was associated with a drop in P1 and P3 methylation level. In conclusion, CD133 expression in neuroblastoma can be regulated by histone acetylation and/or methylation of its CpG promoters. VPA can induce CD133+ cells which display high proliferation potential and low sensitivity to cytostatics in neuroblastoma. These results give new insight into the possible limitations to use VPA in cancer therapy.

The synergistic effects of DNA-damaging drugs cisplatin and etoposide with a histone deacetylase inhibitor valproate in high-risk neuroblastoma cells.

High-risk neuroblastoma remains one of the most important therapeutic challenges for pediatric oncologists. New agents or regimens are urgently needed to improve the treatment outcome of this fatal tumor. We examined the effect of histone deacetylase (HDAC) inhibitors in a combination with other chemotherapeutics on a high-risk neuroblastoma UKF-NB-4 cell line. Treatment of UKF-NB-4 cells with DNA-damaging chemotherapeutics cisplatin or etoposide combined with the HDAC inhibitor valproate (VPA) resulted in the synergistic antitumor effect. This was associated with caspase-3-dependent induction of apoptosis. Another HDAC inhibitor trichostatin A and a derivative of VPA that does not exhibit HDAC inhibitory activity, valpromide, lacked this effect. The synergism was only induced when VPA was combined with cytostatics targeted to cellular DNA; VPA does not potentiate the cytotoxicity of the anticancer drug vincristine that acts by a mechanism different from that of DNA damage. The VPA-mediated sensitization of UKF-NB-4 cells to cisplatin or etoposide was dependent on the sequence of drug administration; the potentiating effect was only produced either by simultaneous treatment with these drugs or when the cells were pretreated with cisplatin or etoposide before their exposure to VPA. The synergistic effects of VPA with cisplatin or etoposide were associated with changes in the acetylation status of histones H3 and H4. The results of this study provide a rationale for clinical evaluation of the combination of VPA and cisplatin or etoposide for treating children suffering from high-risk neuroblastoma.

Vacuolar-ATPase-mediated intracellular sequestration of ellipticine contributes to drug resistance in neuroblastoma cells.

Neuroblastoma is the most common cancer in infants and the fourth most common cancer in children. Aggressive cell growth and chemoresistance are notorious obstacles in neuroblastoma therapy. Exposure to the anticancer drug ellipticine inhibits efficiently growth of neuroblastoma cells and induces apoptosis in these cells. However, ellipticine induced resistance in these cells. The upregulation of a vacuolar (V)-ATPase gene is one of the factors associated with resistance development. In accordance with this finding, we found that levels of V-ATPase protein expression are higher in the ellipticine-resistant UKF-NB-4ELLI line than in the parental ellipticine-sensitive UKF-NB-4 cell line. Treatment of ellipticine-sensitive UKF-NB-4 and ellipticine-resistant UKF-NB-4ELLI cells with ellipticine-induced cytoplasmic vacuolization and ellipticine is concentrated in these vacuoles. Confocal microscopy and staining of the cells with a lysosomal marker suggested these vacuoles as lysosomes. Transmission electron microscopy and no effect of an autophagy inhibitor wortmannin ruled out autophagy. Pretreatment with a V-ATPase inhibitor bafilomycin A and/or the lysosomotropic drug chloroquine prior to ellipticine enhanced the ellipticine­mediated apoptosis and decreased ellipticine-resistance in UKF-NB-4ELLI cells. Moreover, pretreatment with these inhibitors increased formation of ellipticine-derived DNA adducts, one of the most important DNA-damaging mechanisms responsible for ellipticine cytotoxicity. In conclusion, resistance to ellipticine in the tested neuroblastoma cells is associated with V-ATPase-mediated vacuolar trapping of this drug, which may be decreased by bafilomycin A and/or chloroquine.

Hypoxia-mediated histone acetylation and expression of N-myc transcription factor dictate aggressiveness of neuroblastoma cells.

Cells of solid malignancies generally adapt to entire lack of oxygen. Hypoxia induces the expression of several genes, which allows the cells to survive. For DNA transcription, it is necessary that DNA structure is loosened. In addition to structural characteristics of DNA, its epigenetic alterations influence a proper DNA transcription. Since histones play a key role in epigenetics, changes in expression levels of acetylated histones H3 and H4 as well as of hypoxia-inducible factor-1α (HIF-1α) in human neuroblastoma cell lines cultivated under standard or hypoxic conditions (1% O2) were investigated. Moreover, the effect of hypoxia on the expression of two transcription factors, c-Myc and N-myc, was studied. Hypoxic stress increased levels of acetylated histones H3 and H4 in UKF-NB-3 and UKF-NB-4 neuroblastoma cells with N-myc amplification, whereas almost no changes in acetylation of these histones were found in an SK-N-AS neuroblastoma cell line, the line with diploid N-myc status. An increase in histone H4 acetylation caused by hypoxia in UKF-NB-3 and UKF-NB-4 corresponds to increased levels of N-myc transcription factor in these cells.