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A pilot in vivo model of human microcystic lymphatic malformations.

OBJECTIVE
To develop an in vivo mouse model of human microcystic lymphatic malformations (LMs) and provide a tool for investigating the biological mechanisms and treatment of microcystic disease.


DESIGN
Animal model and histologic analysis.


SETTING
Tertiary referral center.


SUBJECTS
Fresh microcystic LM from human subjects were harvested and xenografted in the immunologically naïve nude mice (Athymic Nude- Foxn1(nu)).


MAIN OUTCOME MEASURES
Specimens were divided (5 × 5 × 5 mm) and secured in 4 quadrants subcutaneously along the dorsum of 4 nude mice. Weekly observations for volume, color, and texture of the grafts were performed with sequential harvesting from each quadrant at 30-day intervals. All grafts (n = 16) were sectioned and stained with hematoxylin-eosin. Comparative pathologic evaluation of the grafts and native LM was performed by 2 blinded pathologists. Immunohistochemical analysis for D2-40 (a known lymphatic endothelial cell marker), Ki-67, and human-specific nuclear antigen was performed.


RESULTS
Near complete microcystic LM xenograft survival (n = 13 [81%]) was achieved in the mouse irrespective of the period of implantation. Xenografts underwent a brief growth phase to day 20 to 30 and were quiescent until approximately day 65 but ultimately had a gradual loss of volume following transplant. Histologic analysis revealed structural characteristics matching the native LM tissue. Immunohistochemical analysis found that 10 (77%) of the surviving xenografts (77%) were positive for D2-40, 9 (69%) were positive for human-specific nuclear antigen, and 8 (62%) were positive for Ki-67.


CONCLUSIONS
This preliminary in vivo model suggests that microcystic LM can survive in the athymic nude mouse. The presence of markers for human antibodies, lymphatic endothelium, and cellular proliferation demonstrates the stability of native tissue qualities within the xenografts.