Effects of long-circulating polyethylene glycol (PEG) minocycline-liposomes on the human peripheral blood mononuclear cells (PBMC) in vitro.

<p>Quantitative analysis of the zones of gelatinolysis detected the reduced the proteolytic activity of matrix metalloproteinase (MMP)-9 in the human PBMC sample treated with minocycline (3.0 mg/ml) compared with findings in controls (PBS). A more significant decrease of MMP-9 activity was detected in cells treated with minocycline for 6 hours compared to cells that were treated for 1 hour (A). At 1 hour, there was no significant MMP-9 activity difference among samples treated by the different PEG liposome preparation either with glucose, CaCl₂ or MgCl₂ (A). Time kinetic studies of PEG minocycline-liposomes <i>in vitro</i> revealed that the MMP-9 gelatinolytic activity is significantly reduced at 6 hours after incubation samples with PEG liposome+minocycline (B). Moreover, PEG minocycline-liposome+CaCl₂ treatment inhibited the MMP-9 activity more strikingly than the PEG minocycline-liposome+MgCl₂ preparation (B). Gelatinolytic activity was detectable by gelatin-zymography at molecular weights of 92 kDa, indicative of MMP-9, in the supernatants from all human PBMC samples studied. Incubation with PEG minocycline-liposomes with CaCl₂ resulted in remarkably decreased sizes of the bands at 92 kDa, pointing to decreased activation of MMP-9 in comparison with PEG minocycline-liposomes with MgCl₂ or glucose, respectively (C).