Inhibition of fibroblast-populated collagen lattice contraction by an albumin-bound lipid fraction in human amniotic fluid.

Human amniotic fluid inhibits the contraction of fibroblast-populated collagen lattices. Amniotic fluid of 21 weeks' gestation was previously reported to have peak inhibiting activity. An attempt to isolate the inhibitory factor(s) from human amniotic fluid employing a molecular sieving column demonstrated an inhibitory factor near 70,000 molecular weight (repeated three times with triplicate samples). Since albumin has a molecular weight of 68,000 and is in high concentration in amniotic fluid, the removal of albumin by an Affi-Gel Blue (an albumin binding affinity column) was the first step in the purification scheme. The bound human amniotic fluid albumin fraction was eluted from the Affi-Gel Blue column, and the unexpected finding was that this fraction inhibited fibroblast-populated collagen lattice contraction (three repetitions in duplicate). We previously showed that prostaglandins and saturated and unsaturated fatty acids affect fibroblast-populated collagen lattice contraction, and albumin is a carrier for lipids. The eluted albumin fraction was separated into its protein and lipid components. The lipid-free albumin fraction had no fibroblast-populated collagen lattice contraction inhibiting activity (run four times in duplicate). The isolated lipid fraction inhibited fibroblast-populated collagen lattice contraction in a dose-responsive manner (repeated twice in triplicate). It was demonstrated that lipid bound to albumin isolated from human amniotic fluid inhibited fibroblast-populated collagen lattice contraction.