Biology subjects

Zoellner, H.

Publications and source records attributed to Zoellner, H..

3 recordsLinked to original sources

bioRxiv2021

Cell-Projection Pumping of Fibroblast Contents into Osteosarcoma SAOS-2 Cells Correlates with Increased SAOS-2 Proliferation and Migration, and also with Altered Morphology

We earlier reported that cell-projection pumping transfers fibroblast contents to cancer cells, and this alters cancer cell phenotype. We now report on single-cell tracking of time lapse recordings from co-cultured fluorescent fibroblasts and SAOS-2 osteosarcoma cells, tracking 5,201 cells across 7 experiments. The fluorescent lipophilic marker DiD was used to label fibroblast organelles, and to trace transfer of fibroblast cytoplasm into SAOS-2. We related SAOS-2 phenotypic change to levels of fluorescence transfer from fibroblasts to SAOS-2, and also to what we term compensated fluorescence, that numerically projects mother cell fluorescence post-mitosis, into daughter cells. Comparison of absolute with compensated fluorescence, allowed deduction if phenotypic effects in mother SAOS-2, were inherited by their daughters. SAOS-2 receipt of fibroblast fluorescence correlated by Kendalls tau: with cell-profile area, and without evidence for persistence in daughter cells (median tau = 0.51, p < 0. 016); negatively and weakly with cell circularity, and with evidence for persistence (median tau = -0.19, p < 0.05); and very weakly with cell migration velocity, and without evidence for persistence (median tau = 0.01, p < 0.016). Also, mitotic SAOS-2 had higher rates of prior fluorescence uptake (median = 64.9 units/day), compared with non dividing cells (median = 35.6 units/day, p < 0.016), and there was no evidence for persistence post-mitosis. We conclude there is appreciable impact of cell-projection pumping on cancer cell phenotype, relevant to cancer histopathological diagnosis, clinical spread, and growth, with most effects reset by cancer cell mitosis.

cancer biology↗

bioRxiv2019

Increased cell size, structural complexity and migration of cancer cells acquiring fibroblast organelles by cell-projection pumping

We recently described a hydrodynamic mechanism for cytoplasmic transfer between cells, termed cell-projection pumping (CPP). Earlier image analysis related altered SAOS-2 osteosarcoma cell morphology, to what we now recognize as CPP uptake of fibroblast cytoplasm. We here examine SAOS-2 phenotype following co-culture with human dermal fibroblasts (HDF) in which organelles were pre-labelled with a fluorescent lipophilic marker. Fluorescence activated cell sorting (FACS) analysis was performed of HDF and SAOS-2, cultured either alone or together. FACS forward scatter is proportionate to cell size, and increased for SAOS-2 with high levels of HDF fluorescence uptake (p < 0.004). FACS side scatter is proportionate to internal cell complexity, and increased in SAOS-2 with increasing uptake of HDF fluorescence (p < 0.004), consistent with uptake of HDF organelles. Scratch migration assays revealed that HDF migrated more quickly than SAOS-2 in both isolated cell culture, and following co-culture (p < 0.004). Notably, SAOS-2 with high levels of HDF labelling migrated faster compared with SAOS-2 with low HDF labelling (p < 0.008). A slight and unconvincing reduction in SAOS-2 proliferation was seen (p < 0.02). Similar results were obtained in single additional experiments with A673 and H312 cancer cells. Forward and side scatter results suggest organellar transfer by CPP increases cancer cell morphological diversity. This may contribute to histological pleomorphism relevant to cancer diagnosis and prognosis. Also, increased migration of sub-populations of cancer cells with high CPP organellar uptake, may contribute to invasion and metastasis in-vivo. We thus suggest relevance of CPP to cancer diagnosis and progression.

cancer biology↗

bioRxiv2019

Cell-projection pumping: A hydrodynamic cell-stiffness dependent mechanism for cytoplasmic transfer between mammalian cells

We earlier reported cytoplasmic fluorescence exchange between cultured human fibroblasts (Fib) and malignant cells (MC). Others report similar transfer via either tunneling nanotubes (TNT) or shed membrane vesicles and this changes the phenotype of recipient cells. Our current time-lapse microscopy showed most exchange was from Fib into MC, with less in the reverse direction. Although TNT were seen, we were surprised transfer was not via TNT, but was instead via fine and often branching cell projections that defied direct visual resolution because of their size and rapid movement. Their structure was revealed nonetheless, by their organellar cargo and the grooves they formed indenting MC, while this was consistent with holotomography. Discrete, rapid and highly localized transfer events, evidenced against a role for shed vesicles. Transfer coincided with rapid retraction of the cell-projections, suggesting a hydrodynamic mechanism. Increased hydrodynamic pressure in retracting cell-projections normally returns cytoplasm to the cell body. We hypothesize cell-projection pumping (CPP), where cytoplasm in retracting cell-projections partially equilibrates into adjacent recipient cells via micro-fusions that form temporary inter-cellular cytoplasmic continuities. We tested plausibility for CPP by combined mathematical modelling, comparison of predictions from the model with experimental results, and then computer simulations based on experimental data. The mathematical model predicted preferential CPP into cells with lower cell stiffness, expected from equilibration of pressure towards least resistance. Predictions from the model were satisfied when Fib were co-cultured with MC, and fluorescence exchange related with cell stiffness by atomic force microscopy. When transfer into 5000 simulated recipient MC or Fib was studied in computer simulations, inputting experimental cell stiffness and donor cell fluorescence values generated transfers to simulated recipient cells similar to those seen by experiment. We propose CPP as a potentially novel mechanism in mammalian inter-cellular cytoplasmic transfer and communication. SIGNIFICANCETime-lapse observations of co-cultured cells led us to hypothesize what we believe to be a novel hydrodynamic mechanism transferring cytoplasm between cells. Similar transfer by other mechanisms markedly affects cell behavior. Combined mathematical modelling, satisfaction of predictions from the mathematical model in cell culture experiments, and separate computer simulations that generate outcomes similar to experimental observations, support our hypothesized mechanism.

cell biology↗