Plant-based model for the visual evaluation of electroporated area after irreversible electroporation and its comparison to in-vivo animal data.

Electroporation (EP) is widely used in medicine, such as cancer treatment, in form of electrochemotherapy or irreversible electroporation (IRE). For EP device testing, living cells or tissue inside a living organism (including animals) are needed. Plant-based models seem to be a promising alternative to substitute animal models in research. The aim of this study is to find a suitable plant-based model for visual evaluation of IRE, and to compare the geometry of electroporated areas with in-vivo animal data.For this purpose, a variety of fruit and vegetables were selected and visually evaluated after 0/1/2/4/6/8/12/16/24 h post-EP. Apple and potato were found to be suitable models as they enabled a visual evaluation of the electroporated area. For these models, the size of the electroporated area was determined after 0/1/2/4/6/8/12/16/24 h. For apples, a well-defined electroporated area was visual within two hours, while in potatoes it reached a plateau after eight hours only. The electroporated area of apple, which showed the fastest visual results was then compared to a retrospectively evaluated swine liver IRE dataset which had been obtained for similar conditions. The electroporated area of the apple and swine liver both showed a spherical geometry of comparable size. For all experiments, the standard protocol for human liver IRE was followed. To conclude, potato and apple were found to be suitable plant-based models for the visual evaluation of electroporated area after irreversible EP, with apple being the best choice for fast visual results. Given the comparable range, the size of the electroporated area of the apple may be promising as a quantitative predictor in animal tissue. Even if plant-based models cannot completely replace animal experiments, they can be used in the early stages of EP device development and testing, decreasing animal experiments to the necessary minimum.

Determination of the proliferative fractions in differentiating hematopoietic cell lineages of normal bone marrow.

Because of the proven prognostic value of Ki-67 as a proliferation marker in several types of solid cancers, our goal is to develop and validate a multiparameter flow cytometric assay for the determination of the Ki-67 expression in hemato-oncological diseases. The aim of the present study was to establish the reference values for the fraction of Ki-67 positive cells in and during maturation of individual hematopoietic cell lineages present in normal bone marrow. Aspirates derived from femoral heads of 50 patients undergoing a hip replacement were used for the flow cytometric quantification of Ki-67 expression in the different hematopoietic cell populations of healthy bone marrow. Furthermore, the proliferative index was investigated in detail for the maturation steps during erythro-, myelo-, and monopoiesis using recently described immunophenotypic profiles in combination with a software-based maturation tool. Reference values for the proliferative index were established for different relevant hematopoietic cell populations in healthy bone marrow. During maturation, the size of the Ki-67 positive fraction was the highest in the most immature compartment of the myeloid, monocytic, and erythroid cell lineages, followed by a steady decline upon cell maturation. While proerythroblasts showed a proliferative activity of almost 100%, the myelo- and monoblast showed a lower proliferative index of on average of 50%, indicating that a relatively large proportion of these cells exist in a quiescent state. In conclusion, we can state that when using a novel combination of immunophenotypic markers, the proliferation marker (Ki-67) and a software-based maturation tool, it was possible to determine the proliferative fractions in the diverse hematopoietic cell lineages in bone marrow, in particular during maturation. Using this approach, the proliferative indices for the normal myelo-, mono-, and erythropoiesis were determined, which can be used as a reference in future studies of hematologic malignancies originating from bone marrow. © 2018 International Society for Advancement of Cytometry.