Effect of poly(hydroxybutyrate-co-hydroxyhexanoate) microparticles on growth of murine fibroblast L929 cells

Poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBHHx) microparticles were successfully prepared and their proliferative effects on cultured fibroblasts were studied. PHBHHx microparticles (0.005-0.1 g/L) promoted cell proliferation in murine fibroblast L929 and elevated intracellular calcium concentrations ([Ca²⁺]_i). EGTA (ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid) inhibited PHBHHx microparticle-induced cell proliferation by chelating the extracellular Ca²⁺ and blocking the PHBHHx particle-induced [Ca²⁺]_i increase. Transwell experiments demonstrated that PHBHHx microparticles stimulated fibroblast proliferation when separated from cells by a 0.4 μm filter as effectively as when applied directly to cells. Since PHBHHx microparticles had a diameter of 75 μm, the stimulatory effect of PHBHHx particles on cell growth was attributed to degradation products smaller than 0.4 μm in diameter. The trophic effect of these microparticles is consistent with our previous reports demonstrating good biocompatibility for PHBHHx.