Evom voltohmmeter

The effect of the SNEDDS formulations on the Caco-2 cell monolayer integrity was evaluated by monitoring the transepithelial electrical resistance (TEER) as a function of time, using a Voltohmmeter EVOM (World Precision Instruments, Inc., Sarasota, FL, USA). Monolayers displaying TEER values above 500 Ω cm² were considered appropriate for starting the experiment. 2, 1 and 0.5 h before the transport study, at the beginning (0 h) and at the end (2 h), the TEER values were recorded. After the end of the experiment, the formulations were removed and the monolayers were washed with HBSS buffer. Fresh growth medium was added, and the TEER values were recorded for an additional 1320 min to assess the ability of the cells to recover from treatment.

Primary genital epithelial cells were isolated from cervical and endometrial tissues obtained from women aged 30–59 years (mean age 42.9 ± 7.2) undergoing hysterectomies for benign gynecological reasons at Hamilton Health Sciences Hospital. Informed written consent was obtained in accordance with the approval of the Hamilton Integrated Human Research Ethics Board. A detailed protocol for the isolation and culture of primary GECs has previously been described by Kaushic et al., [26 (link)]. Briefly, endometrial or endocervical tissues were minced into small pieces, digested in an enzyme mixture for an hour at 37 °C. GECs were isolated by a series of separations through nylon mesh filters (Small Parts, Miramar, FL, USA), resuspended in DMEM/F12 primary growth medium (Invitrogen, Burlington, ON, Canada), and seeded onto Matrigel-coated (BD Biosciences, Mississauga, ON, Canada) tissue culture inserts (BD Biosciences). GEC cultures were grown for 5–7 days until confluent monolayers were formed. The confluency was monitored by transepithelial resistance (TER) measured by a volt ohm meter (EVOM; World Precision Instruments, Sarasota, FL, USA). Confluent monolayers showing TER values greater than 1000 Ω/cm² were used for further experiments. The purity of epithelial monolayers was between 95% and 98%, with no trace of any hematopoietic cells.

The ABB integrity after the exposure to the CAs was determined by measuring the transepithelial electrical resistance (TEER) through an EVOM Volt Ohm Meter (World Precision Instruments, Berlin, Germany) equipped with an EndOhm 12 Chamber (World Precision Instruments, Berlin, Germany). TEER of polyester Transwell inserts coated with gelatine 0.2% (Sigma Aldrich), without cells, was measured and set as blank and then TEER was measured before (day 12) and after 24 h of exposure to CAs (day 13). TEER was measured as Ω × cm² and calculated as follows:
where R_M is the experimental value of cell co-culture resistance, R_Blank the experimental value of the blank control and S the surface area of the filter membrane (1.12 cm²). Values of TEER were expressed as % ratio between TEER day 13/TEER day 12. The mean ±SEM of at least three independent experiments was presented.