Preliminary investigation of human lymphatic malformations in vitro.

Abstract

To develop an in vitro model of human lymphatic malformations (LM) that reflects histological characteristics of native LM. Fresh human LM (n = 6) were harvested, sectioned, explanted into a fibrinogen gel, and cultured. A total of 25 explants were developed and observed for primary and peripheral cellular growth. On days 9 to 10, the cultured tissues and gels were collected and fixed in 10% formalin. Primary LM and surrounding gel matrix were sectioned and stained for H&E analysis. Immunohistochemistry was performed for Prox-1 and D2-40, known markers for lymphatic endothelium, and Ki-67, a marker of cellular proliferation. On culture day 3, cells were observed to grow into the gel surrounding the primary tissue explants. Persistent and significant growth into the gel matrix was observed for each specimen at subsequent measurement intervals (day 6 and day 10, P < .0001). H&E staining of all the LM explants demonstrated survival and intact organization and cellular structure reflective of the original LM specimens. Microchannels were observed in the surrounding gel suggesting the presence of newly formed lymphatic vessels. Positive-immunohistochemical staining for D2-40 and Prox-1 revealed organized lymphatic endothelia within each specimen and associated microchannels distal to the explants in the gel matrix. Scattered cells in the gel matrix stained positive for Ki-67. This experimental model suggests that human LM can be preserved and observed to grow in vitro with structural characteristics, and immunohistologic qualities similar to native LM. This model may provide a facile tool for basic and translational research on LM.