NANOSPHERE-RELEASED TETRACYCLINES INHIBIT MMP ACTIVITY OF HUMAN GINGIVAL FIBROBLASTS

Periodontitis results from host inflammatory response to pathogenic infection. Inflammatory-cell molecules like matrix metalloproteinases (MMPs) degrade periodontal tissues. Tetracycline antibiotics such as doxycycline and minocycline have been used in periodontal therapy to treat microbial infection as well as inhibit host MMPs. Further control of drug release and maintenance of effective concentrations may be achieved by incorporation into PLGA nanospheres (NS) embedded in novel PLLA nanofibrous scaffolds (NFS).

Objective: This study sought to determine if doxycyline and minocycline released from PLGA NS inhibit MMP activity of human gingival fibroblasts (hGFs) in a controlled-release manner.

Method: Doxycycline- and minocycline-containing PLGA NS were fabricated using a modified water-in-oil-in-oil emulsion method. Doxycline inhibition of commercial MMP9 was evaluated using gelatin zymography. To test MMP inhibition of NS-released tetracyclines, doxycline NS in PBS were incubated at 37°C. At days 1, 3, 5, 7, 10, and 14, NS/PBS were centrifuged, supernatant was incubated in hGF cell culture overnight then evaluated using gelatin zymography. This process was repeated using minocycline.

Result: Zymography indicated doxycycline inhibited MMP9 in a  dose-dependent manner with a 100 ug dose as optimal. NS-released minocycline had inhibitory effects on hGF MMPs at each evaluation point compared with control groups. NS-released doxycycline had inhibitory effects on human gingival fibroblast MMPs compared with no treatment.

Conclusion: Doxycycline demonstrates dose-dependent MMP9 inhibition. Minocycline released from NS demonstrated greater MMP inhibition versus control; thus, NS encapsulation of tetracyclines preserves some MMP-inhibitory activity.  This drug delivery system offers potential for antimicrobial and anti-MMP activities for tissue engineering applications.