Hanks balanced salt solution (hbss)

The 4T1 cells (0.1 × 10⁶/mL) were plated in an 8-well Nunc™ Lab-Tek™ II Chambered Coverglass dish (Thermo Scientific™, Waltham, MA, USA) with a No. 1.5 borosilicate glass bottom. In their exponential phase of growth, cells were incubated for 24 h in media with a 4.5 mM Gd³⁺ con-centration of mannan-based polymers. After the incubation period, cells were washed twice with Hank’s balanced salt solution (HBSS, Biosera, Nuaille, France), with fluorescent dyes added in concentrations according to the producer’s manual (60–70 nM for LysoTracker^® Green and 1 μg/mL for Hoechst 33342). Incubation times were 60 min for LysoTracker^® Green and 20 min for Hoechst 33,342 [48 ,49 ]. All fluorescent dyes were purchased from Invitrogen™ by Life-Technologies (Prague, Czech Republic). After incubation, the cells were washed twice with HBSS followed by the addition of RPMI 1640 medium without phenol red. Cells were then measured under a TCS SP8 STED 3× microscope (Leica, Chicago, IL, USA; objective: HC PL APO CS2 100×/1.40 OIL). Images were displayed with automatically enhanced contrast and adjusted for brightness using ImageJ (version 1.46r, National Institutes of Health, Bethesda, MD, USA).

THLE-2 cells (derived from primary normal human liver cells) were purchased from American Type Culture Collection (CRL-2706™; Manassas, VA, USA). THLE-2 cells were cultured in LHC-8 medium (Thermo Fisher Scientific, Waltham, MA, USA) supplemented with 10% fetal bovine serum (FBS; EURx, Gdańsk, Poland), 5 ng/mL epidermal growth factor (EGF; Thermo Fisher Scientific, Waltham, MA, USA), 70 ng/mL phosphoethanolamine (Sigma-Aldrich, Saint Louis, MO, USA), and 100 units/mL penicillin/streptomycin (Lonza, Basel, Switzerland). Cells were cultivated under standard conditions: 37 °C with 5% CO₂, and humidified atmosphere in the incubator on a T-75 cm² cell culture flask (Sigma-Aldrich, Saint Louis, MO, USA). To dissociate cell monolayer for the subculture, THLE-2 cells were washed with phosphate-buffered saline (PBS; Lonza, Basel, Switzerland) without calcium and magnesium, followed by treatment with trypsin 0.25%—EDTA in HBSS (Biosera, Nuaille, France)—for 4 min at 37 °C.