Effect of fetal serum on fibroblast pericellular matrix formation

Hyaluronic acid (HA)-dependent pericellular matrices (PCM) play a role in embryonic differentiation of mesodermal cells. Fetal fibroblasts have significantly larger PCMs than postnatal fibroblasts. To determine if this property is intrinsic to fetal fibroblasts or induced by factors in the fetal environment, we studied the effect of fetal bovine serum (FBS) of varying gestational age on human fetal, newborn, and adult fibroblast PCM formation. Cultured human fetal, newborn, and adult fibroblasts were plated in triplicate at a density of 1 x 10(5) cells and incubated in medium alone, medium containing 10% pooled FBS, or FBS from the first, second, or third trimesters. The cells were photographed and morphometric analysis of PCM was performed by the erythrocyte exclusion technique. PCM size was expressed as a ratio of the maximal width of the cell matrix to the maximal width of the cell. The unpaired Student's t test was used for statistical analysis. The earlier the gestational age of FBS used, the larger the PCM observed in fetal and newborn fibroblasts. The PCM of fetal fibroblasts was significantly larger (P < 0.001) than that of newborn and adult fibroblasts at each gestational age of FBS tested (fetal >> newborn > adult). Medium containing pooled FBS caused a significant (P < 0.001) increase in PCM size in all cell lines compared with serum-free medium. There are both intrinsic and extrinsic factors which affect PCM size. These factors which affect HA-dependent PCM size may contribute to a permissive microenvironment for cell migration, proliferation, and development which may be important for scarless fetal wound repair.