Repair kinetics of amnion cells after microsurgical injury

There is a paucity of data regarding healing of fetal membranes. We assessed the repairing ability of a microsurgically-injured monolayer of amnion-derived cells compared to an endothelial cell line.

Amnion-derived cells (FL cells) were grown to confluence in 10% fetal calf serum (FCS). A microsurgical incision was performed under an inverted microscope. The area of each incision was measured at times 0, 6, 12 and 24 h using MCID M4 image analysis software. The experiments were repeated using 1% FCS. The observations were also made replacing the media at 6 and 12 h. Umbilical-cord-derived endothelial cells were used for comparison. The rate of repair of the incision was measured using three methods: (a) absolute closure rate (ACR): (A0-A1)/T, where A0 is the original incisional area, and A1 is the new area at interval T: (b) relative percentage rate (RPR): (A0-A1)/A0/T x 100, and (c) healing rate (HR): (A0-A1)/A0 x 100.

Amnion cells were capable of repairing the microsurgical defect. The ACR decreased over time, and was higher with larger defects. A lower concentration of FCS nor the addition of fresh media altered the repair process significantly. Endothelial cells were significantly faster than amnion cells or amnion-supplemented cells with endothelial media. The RPR remained relatively constant for all groups, suggesting Gompertzian kinetics.

Amnion cells are capable of repairing a surgical defect at a relatively constant percent rate, but are slower than an endothelial cell line. The decreased rate of closure over time may be due to relative contact inhibition. Further studies will concentrate on the molecular and cellular mechanisms involved in this process.