A model for gene therapy of human hereditary lymphedema

Abstract

Primary human lymphedema (Milroy's disease), characterized by a chronic and disfiguring swelling of the extremities, is associated with heterozygous inactivating missense mutations of the gene encoding vascular endothelial growth factor C͞D receptor (VEGFR-3). Here, we describe a mouse model and a possible treatment for primary lymphedema. Like the human patients, the lymphedema (Chy) mice have an inactivating Vegfr3 mutation in their germ line, and swelling of the limbs because of hypoplastic cutaneous, but not visceral, lymphatic vessels. Neuropilin (NRP)-2 bound VEGF-C and was expressed in the visceral, but not in the cutaneous, lymphatic endothelia, suggesting that it may participate in the pathogenesis of lymphedema. By using virus-mediated VEGF-C gene therapy, we were able to generate functional lymphatic vessels in the lymphedema mice. Our results suggest that growth factor gene therapy is applicable to human lymphedema and provide a paradigm for other diseases associated with mutant receptors.

Downregulation of VEGF-C expression in lung and colon cancer cells decelerates tumor growth and inhibits metastasis via multiple mechanisms

“…It binds to Flt4/VEGF receptor 3 (VEGFR3), a receptor tyrosine kinase that is expressed in lymphatic endothelial cells (Joukov et al, 1996), certain non-endothelial cells such as osteoblasts (Orlandini et al, 2006) and many cancer cell types (Strizzi et al, 2001;Jackson et al, 2002;Su et al, 2006;Timoshenko et al, 2007). With significantly lower affinity VEGF-C interacts with VEGFR2, which is primarily involved in the induction of hemangiogenesis (Skobe et al, 1999;Shibuya and Claesson-Welsh, 2006) and coreceptors, including the neuropilin-2 expressed on veins and lymphatic vessels (Karkkainen et al, 2001;Karpanen et al, 2006;Xu et al, 2010). The major physiological function of VEGF-C is generally accepted to be the induction of lymphangiogenesis (reviewed by Bahram and ClaessonWelsh (2010); Tammela and Alitalo (2010)).…”

Development of the lymphatic vascular system: A mystery unravels

“…While neuropilin-1 is predominantly expressed in arterial endothelial cells, NRP-2 is mainly expressed in veins and in visceral lymphatic vessels, whereas its expression is weak in the cutaneous lymphatics (Karkkainen et al, 2001;Hong et al, 2002;Yuan et al, 2002). In addition to defects of neural development, NRP-2-deficient mice show a severe reduction of small lymphatic vessels during development, whereas the mutant mice develop normal arteries, veins, and larger, collecting lymphatic vessels (Yuan et al, 2002).…”

“…In addition to defects of neural development, NRP-2-deficient mice show a severe reduction of small lymphatic vessels during development, whereas the mutant mice develop normal arteries, veins, and larger, collecting lymphatic vessels (Yuan et al, 2002). The finding that NRP-2 binds VEGF-C raises the possibility that VEGF-C signaling through VEGFR-3 may be enhanced by NRP-2 similar to the NRP-1-mediated promotion of VEGF-A signaling to VEGFR-2 (Karkkainen et al, 2001(Karkkainen et al, , 2004. Therefore, the neuropilins serve as multifunctional semaphorin and VEGF family receptors that modulate not only axon guidance, but also angiogenesis and lymphangiogenesis.…”

“…Chy mice, originally generated by ethylnitrosoureainduced mutagenesis, are characterized by chronic lymphedema, and the phenotype recently has been linked to an amino acid substitution mutation in the highly conserved VEGFR-3 tyrosine kinase domain (similar to human Milroy disease; Karkkainen et al, 2001). Targeted overexpression of a soluble form of VEGFR-3 in the skin resulted in the functional blockade of endogenous VEGF-C and VEGF-D signaling and caused a lymphedema-like phenotype (Makinen et al, 2001a).…”

“…To date, VEGF-C is the most promising molecular tool for the treatment of both primary and secondary lymphedema in animal models. Application of a VEGF-C-expressing adenovirus promoted lymphangiogenesis and resulted in the generation of functional new lymphatic vessels in the Chy mutant mice (Karkkainen et al, 2001). Furthermore, when human recombinant VEGF-C was applied to rabbit ears-in which lymphatics were surgically ablated-a single dose of VEGF-C was sufficient to increase lymphangiogenesis and to reverse the tissue hypercellularity of surgically induced lymphedema (Szuba et al, 2002).…”