Effects of negative pressures on epithelial tight junctions and migration in wound healing

Negative-pressure wound therapy has recently gained popularity in chronic wound care. This study attempted to explore effects of different negative pressures on epithelial migration in the woundhealing process. The electric cell-substrate impedance sensing (ECIS) technique was used to create a 5 × 10^-4 cm² wound in the Madin-Darby canine kidney (MDCK) and human keratinocyte (HaCaT) cells. The wounded cells were cultured in a negative pressure incubator at ambient pressure (AP) and negative pressures of 75 mmHg (NP₇₅), 125 mmHg (NP₁₂₅), and 175 mmHg (NP ₁₇₅). The effective time (ET), complete wound healing time (T _max), healing rate (R_heal), cell diameter, and wound area over time at different pressures were evaluated. Traditional wound-healing assays were prepared for fluorescent staining of cells viability, cell junction proteins, including ZO-1 and E-cadherin, and actins. Amount of cell junction proteins at AP and NP₁₂₅ was also quantified. In MDCK cells, the ET (1.25 ± 0.27 h), T_max (1.76 ±0.32 h), and R _heal (2.94 ± 0.62 × 10^-4 cm²/h) at NP₁₂₅ were significantly (P < 0.01) different from those at three other pressure conditions. In HaCaT cells, the T_max (7.34 ± 0.29 h) and Rheal (6.82 ± 0.26 × 10^-5 cm²/h) at NP₁₂₅ were significantly (P < 0.01) different from those at NP₇₅. Prominent cell migration features were identified in cells at the specific negative pressure. Cell migration activities at different pressures can be documented with the real-time wound-healing measurement system. Negative pressure of 125 mmHg can help disassemble the cell junction to enhance epithelial migration and subsequently result in quick wound closure.