CONTROLLED-RELEASE OF TRANSFORMING GROWTH-FACTOR-BETA FROM LIPID-BASED MICROCYLINDERS

The release of transforming growth factor-beta (TGF-beta) from a lipid microstructure has been demonstrated. Lipid microcylinders, with dimensions of 100 X 0.5 mu m and composed of a diacetylenic lipid, have been loaded with 25 ng TGF-beta/mg lipid. Physical and bioactive release characteristics of TGF-beta from these microcylinders and from microcylinders embedded in an agarose hydrogel are reported. Release of TGF-beta from lipid microcylinders follows typical diffusion-limited characteristics, where 10-12% of the TGF is released in the first 10 h at 37 degrees C. The release rate is shown to be temperature controlled and dependent on the integrity of the lipid microcylinder. Immobilization of the lipid microcylinder in a hydrogel matrix composed of agarose and gelatin does not impair the diffusion of TGF-beta from the lipid microcylinders. The utilization of microcylinders as release vehicles in wound repair is discussed.