The microfollicle: a model of the human hair follicle for in vitro studies.

Access to complex in vitro models that recapitulate the unique markers and cell-cell interactions of the hair follicle is rather limited. Creation of scalable, affordable, and relevant in vitro systems which can provide predictive screens of cosmetic ingredients and therapeutic actives for hair health would be highly valued. In this study, we explore the features of the microfollicle, a human hair follicle organoid model based on the spatio-temporally defined co-culture of primary cells. The microfollicle provides a 3D differentiation platform for outer root sheath keratinocytes, dermal papilla fibroblasts, and melanocytes, via epidermal-mesenchymal-neuroectodermal cross-talk. For assay applications, microfollicle cultures were adapted to 96-well plates suitable for medium-throughput testing up to 21 days, and characterized for their spatial and lineage markers. The microfollicles showed hair-specific keratin expression in both early and late stages of cultivation. The gene expression profile of microfollicles was also compared with human clinical biopsy samples in response to the benchmark hair-growth compound, minoxidil. The gene expression changes in microfollicles showed up to 75% overlap with the corresponding gene expression signature observed in the clinical study. Based on our results, the cultivation of the microfollicle appears to be a practical tool for generating testable insights for hair follicle development and offers a complex model for pre-clinical substance testing.

L-Selectin Expression is Influenced by Phosphatase Activity in Chronic Lymphocytic Leukemia.

BACKGROUND: Adhesion receptors have important role in cellular invasiveness and L-selectin is a primary determinant in the binding of chronic lymphocytic leukemia (CLL) cells to several glycated proteins on endothelial cells. We investigated L-selectin expression on CLL cells and explored the mechanisms that lead to their shedding. METHODS: Surface and soluble L-selectin expression levels were studied by flow cytometry and immunoassay, respectively. Magnetically isolated B-cells from patients and controls were investigated for total and protein phosphatase-2A activities. Flow cytometry of permeabilized cells was utilized for the determination of phosphorylated mitogen-activated protein kinase (pp38MAPK) and surface tumor necrosis factor alpha-converting enzyme expression (TACE). RESULTS: In CLL patients elevated absolute lymphocyte cell counts, high soluble and low surface L-selectin expression were observed. Similarly, TACE surface expression was significantly lower on B-CLL cells compared to normal B-cells. Both total phosphatase and protein phosphatase-2A activities were also significantly lower in B-CLL cells compared to normal B-cells and we found a consequently higher level of pp38 MAPK in B-CLL cells. Based on in vitro experiments a MAPK inhibitor could attenuate the phosphatase inhibitor's effect on L-selectin shedding. CONCLUSIONS: The lower phosphatase activity detectable in chronic lymphocytic leukemia, results in a downstream signaling cascade with subsequent reduction of surface L-selectin expression and this effect is mediated by enhanced phosphorylation of p38MAPK and an altered TACE expression. © 2019 The Authors. Cytometry Part B: Clinical Cytometry published by Wiley Periodicals, Inc. on behalf of International Clinical Cytometry Society.

Detection of residual B precursor lymphoblastic leukemia by uniform gating flow cytometry.

BACKGROUND: Residual disease (RD) is an important prognostic factor in acute lymphoblastic leukemia (ALL). Flow cytometry (FC)-based RD detection is easy to perform, but interpretation requires expert analysis due to individual differences among patients. PROCEDURE: We focused at the design of standardized and reproducible RD monitoring in ALL. RD was investigated by a uniform gating strategy, which was designed internationally and tested in one center by Ig/TCR rearrangements. RESULTS: For each gate, positivity cutoff value was assigned using quantification of non-leukemic background. Comparing to Ig/TCR at 0.1% level, 80 of 103 specimens were correctly diagnosed by FC. The predictive value of FC RD at day 15 was then analyzed. In B lineage ALL, day 15 FC significantly correlated with Ig/TCR results at day 33 and/or week 12 (P < 0.01). No significant correlation was found in T lineage ALL. CONCLUSIONS: Thus, FC with preset uniform gating at day 15 predicts PCR-detectable MRD in B precursor ALL. Presented data may be used to define new polychromatic cytometric diagnostics of MRD including semiautomatic assessment. Pediatr Blood Cancer 2010; 54:62-70. (c) 2009 Wiley-Liss, Inc.

A coagulation factor becomes useful in the study of acute leukemias: studies with blood coagulation factor XIII.

The intracellular form of the coagulation factor XIII has previously been identified by immunomorphological techniques using polyclonal antibodies. In these studies, only the A subunit (FXIII-A) was detectable in megakaryocytes/platelets and in monocytes/macrophages. We developed several novel monoclonal antibody clones directed to both subunits (FXIII-A and FXIII-B) and investigated their appearance in normal and leukemic cells. By using 3- and 4-color flow cytometry FXIII expression was investigated in normal peripheral blood and bone marrow samples and in acute myeloblastic (AML) and lymphoblastic (ALL) leukemia cases. Samples were studied by Western blotting and confocal laser scanning microscopy. With a previously published ELISA assay applying two monoclonal antibodies directed to different epitopes in FXIII-A, we were able to measure the intracytoplasmic content of FXIII-A in normal cells and leukemic blasts. FXIII-A was detectable in normal peripheral blood monocytes and in large quantities in platelets, but both cell types were negative for FXIII-B. There was no surface staining for FXIII-A, it only appeared intracellularly. In samples derived from patients with AML M4 and M5, FXIII-A sensitively identified blast cells. Although normal lymphocytes do not express FXIII-A, 40% of ALL cases showed significant FXIII-A expression as determined by flow cytometry. FXIII-A positivity of lymphoblasts was verified by Western blotting, ELISA, and confocal laser scanning microscopy cytometry. These data provide evidence that FXIII-A is a sufficiently sensitive marker in differentiating myeloblasts and monoblasts and is suitable for identifying leukemia-associated phenotypes in ALL.

Early relapse after rituximab chemoimmunotherapy.

In relapsed/refractory childhood acute lymphoblastic leukemia (ALL) of the B-cell lineage rituximab, a monoclonal anti-CD20 antibody was used successfully in some cases. We report on a 15-year-old female with relapsed CD20-positive B-cell progenitor ALL treated with rituximab because of positive minimal residual disease signals after chemotherapy, as checked by flow cytometry and real time quantitative-PCR. Rituximab eliminated the CD20-positive subpopulation, but not the more immature leukemic cells. The patient died with fulminant aspergillosis before hematopoietic stem cell transplantation could be performed.

Leukemic lymphoblasts, a novel expression site of coagulation factor XIII subunit A.

Blood coagulation factor XIII (FXIII) is a protransglutaminase circulating as a tetramer formed by two types of subunits (A2B2). The intracellular dimeric form of FXIII (A2) is present in platelets, megakaryocytes, monocytes and macrophages and has been detected in mono- and megakaryocytic leukemias. The aim of our study was to investigate FXIII-A expression in newly diagnosed B cell acute lymphoblastic leukemia (ALL) samples. We examined 47 de novo ALL cases of B cell origin by triple color labeling with flow cytometry. FXIII-A was detected by a FITC conjugated monoclonal antibody combined with CD34 and CD45 staining. In selected cases FXIII-A was investigated on slides prepared from blasts and visualized with a fluorescent microscope. In addition, blasts were studied by Western blot analysis and FXIII-A was measured by a highly sensitive ELISA method. By flow cytometry 19 samples of the 47 cases were found to be FXIII-A positive. Antigen concentration was 3.11 +/- 1.19 fg/blast, while normal lymphoid precursors and mature lymphocytes from B-CLL did not contain FXIII-A. In the lysate of lymphoblasts that were positive by flow cytometry, a single band (82 kDa) corresponding to FXIII-A was detected on Western blots. Confocal laser scanning microscopic examination revealed the presence of FXIII-A in the cytoplasm of these lymphoblasts. This novel expression site of FXIII-A in leukemic lymphoblasts can be utilized as a diagnostic tool and may also gain functional significance in B-lineage ALL.

Progress in defining multidrug resistance in leukemia.

Multidrug resistance (MDR) is a naturally occurring defense phenomenon by which cells battle against chemically foreign substances (xenobiotics), including some cytotoxic drugs. Membrane transporter hyperactivity is a major contributor to MDR and is the primary target of both diagnostic and therapeutic interventions. Multi-xenobiotic resistance can be exploited as several fluorescent indicator probes are extruded by the same drug transporters, making it possible to quantitatively measure MDR activity in cell lines and clinical samples by flow cytometry. The literature on MDR is reported in a number of different formats, making it difficult to compare data from various groups. This article will briefly review the pathomechanism, then focus upon the diagnostic approach, the interpretation of results from clinical samples and correlations with other variables. The authors believe that a standardized MDR assay, as well as a suitable monitoring test, may become a prognostic marker in several types of leukemia.