A Novel In Vitro Human Model of Hemangioma

Abstract

Hemangioma, the most common tumor of infancy, is characterized by a proliferation of capillary endothelial cells with multilamination of the basement membrane and accumulation of cellular elements, including mast cells. The initial rapid growth is followed by an inevitable but slow involution. The currently available therapies are empirical and unsatisfactory because what is known of the cellular and molecular basis of hemangioma development is rudimentary. Advances in the understanding of its programmed biologic behavior has been hampered by the lack of a valid human model.We report here a novel in vitro culture system that is a useful human model of hemangioma. A small fragment of hemangioma biopsy is embedded in fibrin gel in a well of culture plates and incubated in a serum-free, buffered-salt, minimal medium. A complex network of microvessels grows out from the tissue fragments. Biopsies taken from all three phases of hemangioma development were cultured successfully; proliferative phase samples developed microvessels in 1 to 4 days, involuting phase in 5 to 7 days, and involuted phase in 7 to 12 days. The relative growth rates of the microvessels in the culture of biopsies taken from different stages of hemangioma development reflect the growth patterns seen clinically. This model has been validated using histochemistry, immunohistochemistry, and reverse transcriptase-polymerase chain reaction. Comparison of the number, localization, and phenotype of endothelial and mast cells and the distribution of basement membrane constituents (type IV collagen, perlecan, and laminins) and growth factors (basic fibroblast growth factor, vascular endothelial growth factor, transforming growth factor-␤s) in the biopsy and the tissue after culture shows that many of the characteristics of the original tissues were retained in culture.This in vitro human model of hemangioma overcomes some of the deficiencies associated with earlier models. It offers an opportunity for studying the precise cellular, biochemical, and molecular basis of hemangioma. It may also help to elucidate the mechanisms of action of existing therapies and may lead to the identification of novel treatments for hemangioma.

Insulin-like growth factor 2 and potential regulators of hemangioma growth and involution identified by large-scale expression analysis

“…Recently, Tan et al showed that freshly resected hemangioma tissue placed into fibrin gels develop outgrowths or ''microvessels'' within days after placing into culture (15). Using this system, we demonstrated that IGF-2 stimulated significant sprouting from the intact tissue explant (Fig.…”

“…Resected hemangioma specimens were prepared for culture as described by Tan et al (15). Briefly, fresh hemangioma tissue was cut into fragments (1-2 mm) and embedded into a fibrin gel (3 mg/ml of fibrin͞1 mg/ml of streptomycin͞100 units/ml of penicillin͞10 mg/ml of -amino caproic acid͞20 g/ml of aprotinin͞0.5 units/ml of thrombin in MCDB131 medium).…”

The establishment of the hemangioma model in nude mouse

“…The research of hemangioma at present mostly depends on the study of hemangioma samples obtained from surgery and treatment research carried on in spongelike blood vessels in animal tissue (eg, cockscombor and rat spleen); moreover, there were still other means such as in vitro culture of hemangioma endothelial cells [9]. However, all of these investigations could not reflect the true circs and rules of growth and proliferation of human hemangioma in alive body.…”

Vascular tumors have increased p70 S6-kinase activation and are inhibited by topical rapamycin

“…36 Briefly, 2 mm 3 pieces of freshly resected hemangioma tissue were placed on top of the fibrin gel, which was composed of fibrinogen (3 mg/ml), thrombin (0.5 U/ml) and caproic acid (3 mg/ml) in the M-199 media. Another layer of fibrin gel was then layered on top of the tissue, and covered with the media.…”

“…41,43 The effects of rapamycin in infantile hemangioma were tested in a tissue explant culture system. 36 Freshly resected hemangioma tissues were cultured between two layers of fibrin gel matrix ± rapamycin for 6 days. Rapamycin caused a significant decrease in cellular outgrowths from the explants (Figure 3b).…”