Liposome-associated interferon-alpha-2b functions as an anti-fibrogenic factor for human dermal fibroblasts

This study was conducted to determine whether interferon-alpha-2b (IFN-alpha-2b) can be encapsulated in liposomes without compromising its anti-fibrogenic effects on human dermal fibroblasts. The rationale for this approach is that systemic administration of IFN-alpha-2b by injection for treatment of dermal fibrosis is uncomfortable, requires a large quantity of the cytokine, and cannot be easily used in children. Liposomes are potentially useful as vehicles for the topical delivery of drugs if they can be encapsulated without loss of biologic activity. Empty sonicated vesicles composed of dioleoyl-phosphatidylcholine:dioleoyl-phosphatidylglycerol at a molar ratio of 7:3 were mixed with various concentrations of IFN-alpha-2b and then dried and rehydrated. An enzyme-linked immunosorbent assay (ELISA) was used to determine the efficiency of encapsulation and the stability of the preparation under experimental conditions. Greater than 80% of added IFN-alpha-2b became associated with the liposomes and remained encapsulated for up to 5 d at 4 degrees C. The rate of release increased markedly at 37 degrees C. Liposome-encapsulated IFN-alpha-2b (2000 units per ml) significantly reduced the proliferation of dermal fibroblasts (60 +/- 8.8 vs. 100 +/- 8, mean +/- SEM, p < 0.05, n = 8) and the levels of mRNA for type I (41.5 +/- 8.7% vs 100 +/- 18, p < 0.05, n = 4) and type III (68 +/- 8.4% vs 100 +/- 4.9%, p < 0.05, n = 3) procollagen, as analyzed on northern blots. This was consistent with the reduction found in collagen in conditioned medium from treated fibroblasts. In contrast, treatment increased levels of mRNA for collagenase (241 +/- 42% vs 100 +/- 3.4, p < 0.05, n = 3) and collagenase activity (289 +/- 5.8% vs 100 +/- 10.9%, p < 0.05, n = 9) in conditioned medium. This last effect was probably not due to a reduction in TIMP-1 (tissue inhibitor of metalloproteinase-1) because levels of mRNA for this inhibitor were not lower in treated cells. The efficacy of liposome-associated IFN-alpha-2b in vitro supports the concept of the topical use of this anti-fibrogenic agent for treatment of fibroproliferative disorders.