Human lymphatic malformations (LMs) are a disorder of lymphatic vascular embryonic development, characterised by multiple lymph fluid containing cysts. The aim of this study was to isolate LM endothelial cells (ECs), characterise their in vitro behaviour and develop a LM mouse model suitable for experimental investigation of LM biology.
In vitro: Lymphatic ECs (LECs) were isolated from human LMs and from paediatric foreskin samples using a CD34-CD31+ selection strategy. The cells were examined for their ability to proliferate and survive under starvation conditions, form tubules and migrate. In vivo: Lymphatic EC and LM ECs (passage 4) resuspended in Matrigel™ were implanted into a mouse tissue engineering chamber (n=3 per time point per group). Tissue chambers were harvested at 1, 2 and 4 weeks post implantation and examined for presence of human lymphatic and LM-like structures using LEC markers CD31, VEGFR-3 and D2-40. The animal-developed LM vessels were compared to parent LM tissues from which the implanted cells were derived.
LM ECs showed increased proliferation and survival under starvation conditions, increased migration and formed fewer, shorter tubes than foreskin LECs. In vivo LM ECs assembled into vessels with dilated cystic lumens lined with flat endothelium, features consistent with human LMs. In contrast, LECs were rarely observed, with most cells failing to survive implantation.
In conclusion, LM ECs showed increased proliferation, survival and migration, and decreased tubulogenesis compared to LECs.LM ECs implanted into a mouse tissue engineering chamber assembled into LM-like structures stable at 4 weeks, resembling the original lesion from which they were isolated.