Epithelial cells as alternative human biomatrices for comet assay.

The comet assay is a valuable experimental tool aimed at mapping DNA damage in human cells in vivo for environmental and occupational monitoring, as well as for therapeutic purposes, such as storage prior to transplant, during tissue engineering, and in experimental ex vivo assays. Furthermore, due to its great versatility, the comet assay allows to explore the use of alternative cell types to assess DNA damage, such as epithelial cells. Epithelial cells, as specialized components of many organs, have the potential to serve as biomatrices that can be used to evaluate genotoxicity and may also serve as early effect biomarkers. Furthermore, 80% of solid cancers are of epithelial origin, which points to the importance of studying DNA damage in these tissues. Indeed, studies including comet assay in epithelial cells have either clear clinical applications (lens and corneal epithelial cells) or examine genotoxicity within human biomonitoring and in vitro studies. We here review improvements in determining DNA damage using the comet assay by employing lens, corneal, tear duct, buccal, and nasal epithelial cells. For some of these tissues invasive sampling procedures are needed. Desquamated epithelial cells must be obtained and dissociated prior to examination using the comet assay, and such procedures may induce varying amounts of DNA damage. Buccal epithelial cells require lysis enriched with proteinase K to obtain free nucleosomes. Over a 30 year period, the comet assay in epithelial cells has been little employed, however its use indicates that it could be an extraordinary tool not only for risk assessment, but also for diagnosis, prognosis of treatments and diseases.

Clinical transplantation of ex vivo expanded autologous limbal epithelial cells using a culture medium with human serum as single supplement: a retrospective case series.

PURPOSE: Presently, our clinic is the only centre in Scandinavia that offers patients with corneal surface pathology including limbal stem cell deficiency (LSCD) transplantation of ex vivo expanded limbal epithelial cells (LECs). We here present clinical data of the first nine patients with LSCD who were transplanted with autologous LECs expanded in medium completely free of any animal-derived products and non-human/recombinant growth factors (including Cholera Toxin), and with autologous human serum as the only growth supplement. METHODS: We conducted a noncomparative retrospective study of patients with LSCD at our centre between 2009 and 2011. The diagnosis was based on history and clinical signs. A biopsy was taken from healthy limbus, and the epithelium was expanded on amniotic membrane (AM) in medium containing autologous serum and subsequently transplanted to the affected eye. RESULTS: Successful outcome was defined as relief of pain and photophobia and/or improved best corrected visual acuity (BCVA) and/or reestablishment of a stable corneal epithelium and regression of corneal vascularization. Five of the nine transplanted patients (55.6%) had an improvement in either subjective symptoms or objective findings (11- to 28-month follow-up). CONCLUSIONS: Our clinical study shows that patients with LSCD can be treated successfully with transplantation of LECs expanded ex vivo in a medium with autologous serum as the only growth supplement. The use of this novel culture system, which is devoid of animal-derived products and non-human/recombinant growth factors (including Cholera Toxin), reduces the risks of inter-species disease transmission and host immune responses to xenogenic proteins, both obvious advantages for the patient.

Donor cornea transfer from Optisol GS to organ culture storage: a two-step procedure to increase donor tissue lifespan.

PURPOSE: Storage time for donor corneas in Optisol GS is limited compared to Eye Bank Organ Culture (EBOC). We here examine the epithelium on donor corneoscleral rims after primary storage in Optisol GS and subsequent incubation in EBOC. METHODS: Morphology was monitored by light and electron microscopy, expression of phenotypic and genotypic markers by immunohistochemistry and RT-PCR and changes in oxidative lipid and DNA damage by ELISA and COMET assay. RESULTS: A prominent loss of cells was observed after storage in Optisol GS. After maintenance in EBOC, spreading apical cells were Occludin(+) , while the staining for E-cadherin and Connexin-43 was less intense. There were an upregulation of Occludin and a downregulation of E-cadherin and Connexin-43. Eye Bank Organ Culture was associated with an ongoing proliferative activity and a downregulation of putative progenitor/stem cell marker ABCG2 and p63. Staining for 8-OHdG and Caspase-3 did not increase, while levels of malondialdehyde and number of DNA strand breaks and oxidized bases increased. CONCLUSIONS: This dual procedure should be pursued as an option to increase the storage time and the pool of available donor corneas. The observed downregulation of markers associated with stemness during EBOC is relevant considering the potential use of donor epithelium in the treatment of ocular surface disorders.

Oxidative stress gradient in a medium during human corneal organ culture.

PURPOSE: Lipid peroxidation content was measured in an organ culture medium after one-week storage of human donor corneas. Moreover, the effects of the medium on oxidative stress, antioxidant capacity, and the proliferation of cultured human corneal cells were studied. METHODS: The medium was sampled from the upper and lower halves of storage vials and from controls (n=42). Malondialdehyde (MDA) was measured by high pressure liquid chromatography (HPLC). Cultured human corneal epithelium (CRL-11515) was exposed to different medium samples and monitored for changes in MDA (enzyme-linked immunosorbent assay [ELISA]), total antioxidant capacity (antioxidant assay kit), and proliferation (Ki-67). RESULTS: A significant increase in MDA was observed in the organ culture medium in the lower level of storage vials. The addition of this fraction to cultured cells increased MDA significantly after 3 days, and the medium from both levels significantly increased MDA after 7 days. The medium from both levels significantly decreased the total antioxidant capacity of the cells but did not affect proliferative activity. CONCLUSIONS: An oxidative gradient with an evident biologic effect is established in the medium in vials during organ culture of human donor corneas. Donor tissue stored at the bottom or in lower levels of such vials is exposed to a significant amount of oxidative stress.

Ex vivo expanded autologous limbal epithelial cells on amniotic membrane using a culture medium with human serum as single supplement.

In patients with limbal stem cell deficiency (LSCD), transplantation of ex vivo expanded human limbal epithelial cells (HLECs) can restore the structural and functional integrity of the corneal surface. However, the protocol for cultivation and transplantation of HLECs differ significantly, and in most protocols growth additives such as cholera toxins, exogenous growth factors, hormones and fetal calf serum are used. In the present article, we compare for the first time human limbal epithelial cells (HLECs) cultivated on human amniotic membrane (HAM) in a complex medium (COM) including fetal bovine serum to a medium with human serum as single growth supplement (HSM), and report on our first examinations of HLECs expanded in autologous HSM and used for transplant procedures in patients with LSCD. Expanded HLECs were examined by genome-wide microarray, RT-PCR, Western blotting, and for cell viability, morphology, expression of immunohistochemical markers and colony forming efficiency. Cultivation of HLECs in HSM produced a multilayered epithelium where cells with markers associated with LESCs were detected in the basal layers. There were few transcriptional differences and comparable cell viability between cells cultivated in HSM and COM. The p63 gene associated with LESCs were expressed 3.5 fold more in HSM compared to COM, and Western blotting confirmed a stronger p63α band in HSM cultures. The cornea-specific keratin CK12 was equally found in both culture conditions, while there were significantly more CK3 positive cells in HSM. Cells in epithelial sheets on HAM remaining after transplant surgery of patients with LSCD expressed central epithelial characteristics, and dissociated cells cultured at low density on growth-arrested fibroblasts produced clones containing 21 ± 12% cells positive for p63α (n = 3). In conclusion, a culture medium without growth additives derived from animals or from animal cell cultures and with human serum as single growth supplement may serve as an equivalent replacement for the commonly used complex medium for ex vivo expansion of HLECs on HAM.

Cellular response to irinotecan in colon cancer cell lines showing differential response to 5-fluorouracil.

BACKGROUND: Use of irinotecan (CPT-11) as second-line therapy for metastatic colorectal cancer has shown some promise in cases where 5-fluorouracil (5-FU) has failed. Cross-resistance to both drugs may however be a potential clinical problem. The cellular response to CPT-11 was investigated in two human colon cancer cell lines that demonstrate a differential response to 5-FU. MATERIALS AND METHODS: Cell cycle progression, clonogenic survival, DNA damage checkpoint activation, apoptosis induction and senescence development were assessed during 48 hours of treatment and 72 hours of recovery. RESULTS: Both cell lines had similar cellular response patterns to CPT-11. Growth inhibition, loss of clonogenicity, ataxia telangiectasia mutated (ATM) activation, H2AX phosphorylation, TP53 stabilization, CDKN1A induction, G2/M arrests, endoreduplication, negligible cell death and appearance of a senescence-associated beta-galactosidase phenotype were observed. CONCLUSION: Cross-resistance to 5-FU and CPT-11 was not demonstrated. The appearance of a senescence phenotype in response to CPT-11 treatment may have potential clinical relevance for treatment regimens.

Effects of organ culture and Optisol-GS storage on structural integrity, phenotypes, and apoptosis in cultured corneal epithelium.

PURPOSE: A previous report has described the use of eye bank storage of cultured human limbal epithelial cells (HLECs) to provide a reliable source of tissue for treating limbal stem cell deficiency. In the present study, conventional organ culture (OC) storage and Optisol-GS (Bausch & Lomb, Irvine, CA) storage of cultured HLECs were compared. METHODS: Three-week HLEC cultures were either organ cultured at 31 degrees C or 23 degrees C or stored in Optisol-GS at 5 degrees C in a closed container for 1 week. Morphology was studied by light microscopy and transmission electron microscopy, and phenotypic characterization was assessed by immunohistochemistry. Apoptosis was evaluated by real-time RT-PCR microarray analysis, caspase-3 immunohistochemistry, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). RESULTS: The ultrastructure was preserved at 23 degrees C, while storage at 31 degrees C and 5 degrees C was associated with enlarged intercellular spaces, separation of desmosomes, and detachment of epithelial cells. Cultured HLECs remained undifferentiated in all storage conditions. The expression of the antiapoptotic gene BCL2 was prominently upregulated in storage at 23 degrees C and 5 degrees C. Downregulation of BCL2A1, BIRC1, and TNF and upregulation of CARD6 in 23 degrees C and 5 degrees C storage conditions suggests a reduction in nuclear factor-kappaB activity. No significant increase in cleaved caspase-3 and TUNEL staining was observed in response to eye bank storage, and the labeling indices of cleaved caspase-3 (range, 0.0%-4.7%) and TUNEL (range, 0.0%-7.8%) were low. CONCLUSIONS: These data indicate that OC storage of cultured HLECs at ambient temperature is superior to OC storage at 31 degrees C and Optisol-GS storage at 5 degrees C and that apoptosis is minimal after eye bank storage of cultured HLECs.

Chromosomal 20q gain in the DNA diploid component of aneuploid colorectal carcinomas.

The order of appearance of different genetic aberrations during the shift from diploidy/near-diploidy to aneuploidy in colorectal cancers is not yet clear. We studied genetic alterations in flow cytometrically-sorted DNA diploid and corresponding aneuploid epithelial cell populations from each of 20 colorectal tumors using comparative genomic hybridization, FISH, and PCR. Analysis of the 19 cases in which aberrations were found in the flow-sorted diploid population indicated that large-scale aneuploidization in colorectal cancer was preceded by amplification of oncogene(s) localized to chromosome 20q13.2 and by KRAS mutations, but not by TP53 deletions or losses of large chromosomal regions such as 4q, 8p and 18q.

Nuclear expression of survivin is associated with improved survival in metastatic ovarian carcinoma.

BACKGROUND: Inhibitor of apoptosis proteins (IAPs) mediate cancer cell survival and chemoresistance. The expression of XIAP, Survivin, and Livin in ovarian carcinoma was analyzed. METHODS: Effusions (106) were analyzed for XIAP, Survivin, and Livin expression using immunoblotting. Effusions (220), corresponding primary tumors (60), and solid metastases (103) were further immunohistochemically analyzed for XIAP and Survivin expression. The results were analyzed for association with anatomic site, clinicopathologic parameters, and survival. RESULTS: Immunoblotting showed frequent expression of XIAP and Survivin, and no expression of Livin. Immunohistochemistry showed cytoplasmic XIAP expression in 208 of 220 (94%) effusions, 50 of 60 (83%) primary tumors, and 87 of 103 (84%) solid metastases, with a significantly higher staining extent in effusions (P < .001). Cytoplasmic Survivin was found in 194 of 220 (88%) effusions, 55 of 60 (92%) primary tumors, and 102 of 103 (99%) solid metastases, with a significantly higher cytoplasmic staining extent in solid metastases (P = .018 and P = .006 compared with primary tumors and effusions, respectively). Nuclear Survivin was expressed in 159 of 220 (72%) effusions, 54 of 60 (90%) primary carcinomas, and 96 of 103 (93%) solid metastases (P > .05). For patients with prechemotherapy effusions, higher nuclear Survivin expression correlated with better progression-free (P = .0003) and overall (P = .002) survival in univariate survival analysis. Nuclear Survivin expression was found to be an independent predictor of progression-free survival (P = .004). CONCLUSIONS: XIAP and Survivin, but not Livin, are frequently expressed in ovarian carcinoma. XIAP and cytoplasmic Survivin are up-regulated in effusions and solid metastases, respectively, possibly mediating survival at these sites. Nuclear Survivin expression predicts better outcome in prechemotherapy patients.