Human Embryonic Stem Cell–Derived Endothelial Precursor Cell Conditioned Medium Reduces the Thickness of the Capsule Around Silicone Implants in Rats

Background We postulated that the fibrotic capsule around a silicone implant could be induced by ischemic conditions, based on previous reports that hypoxia is an important microenvironmental factor in the development of tissue fibrosis. Objective This study aimed to determine the effect of human embryonic stem cell (hESC)-derived endothelial precursor cell (EPC) conditioned medium (CM), which has strong angiogenic potential, on the development of capsule around the silicone implant in a rat model. Methods and Materials Three groups had a mini-silicone implant with a smooth surface inserted. In 2 experimental groups, hESC-EPC CM was administered into the subcutaneous pocket either 1 or 2 times. After 2 months, the capsules were harvested and analyzed by histologic examination. Results There was a significant reduction in the thickness of the peri-implant capsules (P < 0.05) between the control and experimental groups. There is no tendency that hESC-EPC CM reduces inflammatory reaction in early postoperative periods. The experimental group showed increased angiogenesis compared to the control group (P < 0.05). Conclusions Tissue hypoxia around the implant may be another cause for the peri-implant capsule. A preventive or therapeutic strategy to decrease capsular contracture by relieving the ischemic condition around the implant can be investigated in the future.