[Asbestos: detection and characterization in tissue]. / Asbest: Nachweis und Charakterisierung im Gewebe.

BACKGROUND: When asbestos fibers are inhaled, asbestos bodies can form in the lungs with the involvement of macrophages. It can take decades from the last exposure to the onset of an asbestos-related disease. OBJECTIVES: The aim of this review is to present methods to detect asbestos bodies in lung tissue, the development of diagnostic criteria and to discuss pros and cons of different methods. MATERIALS AND METHODS: Observations and evaluations from the German Mesothelioma Register, along with relevant literature review and expert recommendations in guidelines are presented. RESULTS: Assessing asbestos-related diseases requires recognition of the person's occupational history, the asbestos fiber burden in the lungs, and determining fiber types. Various methods have been developed and validated, including light microscopy techniques such as bright-field microscopy, phase-contrast microscopy, polarization microscopy, and differential interference microscopy, as well as electron microscopy techniques like field-emission-scanning electron microscopy (e.g., FE-SEM) and transmission electron microscopy (TEM). CONCLUSION: The use of asbestos has been heavily restricted worldwide, even completely banned in Europe. Thus, patients' exposure to asbestos is decreasing. However, asbestos exposure during renovations, demolitions, or through unconscious handling of asbestos-containing materials remains a concern.

Exposure of Patient-Derived Mesenchymal Stromal Cells to TGFB1 Supports Fibrosis Induction in a Pediatric Acute Megakaryoblastic Leukemia Model.

Bone marrow fibrosis (BMF) is a rare complication in acute leukemia. In pediatrics, it predominantly occurs in acute megakaryoblastic leukemia (AMKL) and especially in patients with trisomy 21, called myeloid leukemia in Down syndrome (ML-DS). Defects in mesenchymal stromal cells (MSC) and cytokines specifically released by the myeloid blasts are thought to be the main drivers of fibrosis in the bone marrow niche (BMN). To model the BMN of pediatric patients with AMKL in mice, we first established MSCs from pediatric patients with AMKL (n = 5) and ML-DS (n = 9). Healthy donor control MSCs (n = 6) were generated from unaffected children and adolescents ≤18 years of age. Steady-state analyses of the MSCs revealed that patient-derived MSCs exhibited decreased adipogenic differentiation potential and enrichment of proliferation-associated genes. Importantly, TGFB1 exposure in vitro promoted early profibrotic changes in all three MSC entities. To study BMF induction for longer periods of time, we created an in vivo humanized artificial BMN subcutaneously in immunodeficient NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice, using a mixture of MSCs, human umbilical vein endothelial cell, and Matrigel. Injection of AMKL blasts as producers of TGFB1 into this BMN after 8 weeks induced fibrosis grade I/II in a dose-dependent fashion over a time period of 4 weeks. Thus, our study developed a humanized mouse model that will be instrumental to specifically examine leukemogenesis and therapeutic targets for AMKL blasts in future. IMPLICATIONS: TGFB1 supports fibrosis induction in a pediatric AMKL model generated with patient-derived MSCs. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/18/10/1603/F1.large.jpg.