(I-336) "Impact of 3-D Confinement on the Migratory Behavior of Young and Aged Cells: Implications for Cellular Senescence and Age-Related Decline"

Introduction::

Cell migration is required for development, wound healing, and tissue regeneration. Unregulated cell motility can lead to the emergence of pathophysiological events, including cancer metastasis. The widely held view is that as cells age or senesce, their motility naturally decreases. Most of these studies have been carried out on two-dimensional (2D) planar surfaces. However, in vivo, cells migrate through confined, three-dimensional topographies, including micropores and narrow longitudinal channel-like tracks. Confinement is known to induce physical stress on cells, altering their migration modes and mechanisms. To date, the impact of confinement on the migratory behavior of aged and young cells remains unknown.

Materials and Methods::

To compare the motility of confined cells, we fabricated polydimethylsiloxane (PDMS)-based microchannel devices using multilayer photolithography and replica molding. The device consisted of two large 2D-like channels in parallel with several microchannels running perpendicularly between them. The microchannels varied in (W)idth and (H)eight but maintained a fixed (L)ength (L= 200 µm). The dimensions of microchannels for each device were W × H = ~10× 10 µm², W × H = ~10× 3 µm², W × H = ~3 × 10 µm², and W × H = ~10 × 6 µm². For each experiment, suspensions of early (10-15) and late ( >25) passage human dermal fibroblasts were added into the inlet side of one of the larger channels to generate a pressure-driven flow. Devices were then placed in an incubator for 10 minutes at 37˚C, allowing the cells to adhere next to the openings of the microchannels. Additional media was provided and the devices were placed under a Nikon Ti2 Inverted Microscope with a Tokai Stage-Top Incubator that enables control of atmospheric conditions. Each experiment lasted 16 hours, with imaging of each device taken every 10 minutes. The MTrackJ plugin was used to track cell movement, and the percent cell entry into microchannels along with persistence, velocity, and speed within microchannels were calculated for each device. All experiments were conducted three times and statistical significance was determined using appropriate statistical tests (e.g., student's t-test for two groups or one-way analysis of variance (ANOVA) test followed by Tukey's test for multiple comparisons).

Results, Conclusions, and Discussions::

Cells with 10-15 passages were considered young, while those with passage numbers above 25 were classified as old due to their ceased division and high senescence-associated beta-galactosidase levels. Experiments with young cells indicated a significant decrease in speed and velocity as the degree of confinement increased. However, no significant difference in cell entry was observed among the devices. Additionally, experiments with young cells where a chemotactic gradient was introduced to increase cell migration in confinement confirmed that speed and velocity decreased with increasing confinement.

In the weeks leading up to the conference, we will assess the effects of confinement on the migratory behavior of old cells. Once the baseline cell motility has been established for both young and old cells, further investigations will focus on how key modulators of cell migration such as myosin II, actin, focal adhesion, and nucleus affect the motility of old vs young cells in confinement. The goal is to modulate pathways to rejuvenate aged cells, enabling them to mimic the behavior of young cells. This research aims to mitigate the adverse effects of cellular senescence on cell function, presenting promising possibilities for combating age-related cellular decline.

Acknowledgements (Optional): : Mistriotis Lab at Auburn University including Farnaz Hemmati, Aybua Akinpelu, Farshad Amiri, Dylan Bowen, Ravi Vaghasiya, and of course, Dr. Mistriotis.

References (Optional): :