Simulated Microgravity-Induced Changes to Drug Response in Cancer Cells Quantified Using Fluorescence Morphometry

Abstract

Unlike plants that have special gravity-sensing cells, such special cells in animals are yet to be discovered. However, microgravity, the condition of apparent weightlessness, causes bone, muscular and immune system dysfunctions in astronauts following spaceflights. Decades of investigations show correlations between these organ and system-level dysfunctions with changes induced at the cellular level both by simulated microgravity as well as microgravity conditions in outer space. Changes in single bone, muscle and immune cells include morphological abnormalities, altered gene expression, protein expression, metabolic pathways and signaling pathways. These suggest that human cells mount some response to microgravity. However, the implications of such adjustments on many cellular functions and responses are not clear. Here, we addressed the question whether microgravity induces alterations to drug response in cancer cells. We used both adherent cancer cells (T98G) and cancer cells in suspension (K562) to confirm the known effects of simulated microgravity and then treated the K562 cells with common cancer drugs (hydroxyurea and paclitaxel) following 48 h of exposure to simulated microgravity via a NASA-developed rotary cell culture system. Through fluorescence-guided morphometry, we found that microgravity abolished a significant reduction (p < 0.01) in the nuclear-to-cytoplasm ratio of cancer cells treated with hydroxyurea. Our results call for more studies on the impact of microgravity on cellular drug response, in light of the growing need for space medicine, as space exploration grows.

Microfluidic Microcirculation Mimetic for Exploring Biophysical Mechanisms of Chemotherapy-Induced Metastasis

“…However, fluorescence-guided morphometry independent of the MMM was performed using a Zeiss Vert.A1 AXIO fluorescence microscope (Carl Zeiss, Jena, Germany) equipped with red, green and blue filters and with an inserted USB microscope camera (AmScope MU300, Ningbo, China), along with its AmScope (86x) image capture program. Details of the advanced fluorometric morphometry performed which yielded information on cytoplasmic cross section and nuclear cross section, following chemotherapeutic interventions, can be found in our recent publications [ 57 , 58 ]. Briefly, the fluorescent dyes Hoechst 33342 (ThermoFisher Scientific, Waltham, MA, USA), at a 0.1 mM final concentration, and Calcein AM (Invitrogen by ThermoFisher Scientific, Waltham, MA, USA), at a final concentration of 1 µg/mL, were used to stain the nucleus and the cytoplasm, respectively, for imaging.…”

Omics Studies of Tumor Cells under Microgravity Conditions

“…Moreover, it has been observed that µg can change the way chemotherapy drugs work. However, there have been limited r-µg studies or animal experiments in space, while most research was conducted on cell culture lines under s-µg conditions [93,94]. Tumor diseases remain the most significant global challenges and, despite scientific advancements in medicine, no conclusive methods have been discovered to prevent tumor development or guide its treatment.…”