In recent years, a special type of cancer cell-the cancer stem cell (CSC)-has been identified and characterized for different tumors. CSCs may be responsible for the recurrence of a tumor following a primarily successful therapy and are thought to bear a high metastatic potential. For the development of efficient treatment strategies, the establishment of reliable methods for the identification and effective isolation of CSCs is imperative. Similar to their stem cell counterparts in bone marrow or small intestine, different cluster of differentiation surface antigens have been characterized, thus enabling researchers to identify them within the tumor bulk and to determine their degree of differentiation. In addition, functional properties characteristic of stem cells can be measured. Side population analysis is based on the stem cell-specific activity of certain ATP-binding cassette transporter proteins, which are able to transport fluorescent dyes out of the cells. Furthermore, the stem cell-specific presence of aldehyde dehydrogenase isoform 1 can be used for CSC labeling. However, the flow cytometric analysis of these CSC functional features requires specific technical adjustments. This review focuses on the principles and strategies of the flow cytometric analysis of CSCs and provides an overview of current protocols as well as technical requirements and pitfalls. A special focus is set on side population analysis and analysis of ALDH activity. Flow cytometrybased sorting principles and future flow cytometric applications for CSC analysis are also discussed. ' 2012 International Society for Advancement of Cytometry

Lacrimal gland (LG) insufficiency is a main cause for severe dry eye leading to pain, visual impairment, and eventually loss of sight. Engineering of transplantable LG tissue with secretory capacity is a desirable goal. In this study, a three-dimensional decellularized LG (DC-LG) scaffold with preserved LG morphology was generated by treatment with 1% sodium deoxycholate and DNase solution using porcine LG tissue. To address clinical applicability, the primary in vitro culture of secretory active LG cells from a small tissue biopsy of 1.5 mm diameter was introduced and compared with an established isolation method by enzymatic digestion. Cells from both isolation methods depicted an epithelial phenotype, maintained their secretory capacity for up to 30 days, and exhibited progenitor cell capacity as measured by aldehyde dehydrogenase-1 activity, side population assay, and colony-forming units. Cells from passage 0 were reseeded into the DC-LG and secretory active cells migrated into the tissue. The cells resembled an LG-like morphology and the constructs showed secretory activity. These results demonstrate the possibility of engineering a secretory competent, three-dimensional LG construct using LG cells expanded from a small tissue biopsy and DC-LG as a matrix that provides the native structure and physiological niche for these cells.

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In vitro expansion in low oxygen preserves the proliferation capacity and differentiation potential of LG-MSC and increases the effects of conditioned medium on migration and proliferation in LG-EC. Therefore, expansion in low oxygen seems to be an excellent method, to obtain vital MSC. Also, an increased number of LG-MSC expressing CD44 was observed under low oxygen, which might be a valuable marker to identify a potent MSC subpopulation.

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Imiquimod cream (5%) provides an effective alternative therapy for the treatment of nodular BCC of the eyelid, although surgical treatment remains the gold standard at the present time. This study is the first to assess the long-term efficacy and safety of this approach. Trial studies are necessary.

The extracellular matrix (ECM) of the limbus provides a tissue specific morphology and three-dimensionality consisting of particular ECM proteins. It therefore represents a substantial component of the stem cell niche. The DHL provides a specific limbal niche surrounding, and might serve as an easily producible carrier matrix for LESC transplantation.

Polo-like kinase 1 (PLK1) is a regulator of mitosis and its upregulation in tumours is often associated with poor prognosis. Although PLK1 inhibitors have already entered phase 1 clinical trials, little is known about their impact on the treatment of paediatric malignancies. Thus, we evaluated the concept of PKL1 inhibition by testing the effects of the PLK1 inhibitor GW843682X alone and in combination with the topoisomerase 1 inhibitor, camptothecin, against a panel of 18 paediatric tumour cell lines. Cytotoxicity was evaluated by MTT test and by caspase 3/7 activation. Expression of target was confirmed by western blot analysis. Expression of ATP binding cassette transporters was analysed by quantitative real-time reverse transcription PCR. GW843682X significantly inhibited cell growth in all 18 cell lines. Concentrations, which inhibited cell growth by 50% compared with untreated controls after 72 h, ranged from 0.02 to 11.7 μmol/l. Apart from the N-Myc-amplified neuroblastoma cell lines, the osteosarcoma cell lines MNNG-HOS and OST, which are highly resistant to standard anticancer drugs, were sensitive to GW843682X. The toxicity of GW843682X was dependent neither on the ATP binding cassette drug transporter expression nor on the p53 mutation status. Neither synergistic nor antagonistic effects were observed for the combination of GW843682X and camptothecin in 14 cell lines. GW843682X showed considerable toxicity against a panel of paediatric tumour cell lines suggesting that PLK1 inhibitors under clinical development should be evaluated against paediatric malignancies too.