Kari Alitalo: Vascular Growth Factor Group

Members of the VEGF family, consisting of five mammalian proteins, are key regulators of blood and lymphatic vessel development and growth. VEGFs promote angiogenesis and lymphangiogenesis by activating VEGF receptor (VEGFR) tyrosine kinases in endothelial cells. In both physiological and pathological angiogenesis, insufficient oxygen triggers VEGF production, which stimulates vessel growth primarily through VEGFR-2, while VEGFR-1 primarily functions as a decoy receptor with minimal signal transduction. Although VEGF-blocking antibodies have been successfully used in cancer therapy, attempts to use VEGF for proangiogenic therapy in tissue ischemia have been hindered by VEGF-induced vascular leakage and abnormal vessel growth.

Since its discovery over 30 years ago, VEGF-B has remained somewhat enigmatic. However, we have demonstrated that VEGF-B can protect against myocardial infarction by expanding the coronary vasculature and increasing cardiac muscle mass. Moreover, VEGF-B expression is reduced in failing hearts. These findings suggest that VEGF-B therapy offers a unique opportunity to remodel the myocardial vasculature, enhancing blood flow in the heart and adipose tissue. Our studies also indicate that VEGF-B can improve glucose and insulin tolerance in obese mice.

In adults, VEGFR-3, the receptor for VEGF-C and VEGF-D, is primarily expressed in the lymphatic vasculature, where VEGF-C regulates lymphatic vessel growth. However, VEGFR-3 is also present in growing blood vessels. In 2015, we discovered a meningeal lymphatic vessel system surrounding the brain. These meningeal lymphatics may play a role in various neurodegenerative and neuroinflammatory diseases that pose a significant socioeconomic burden. Ongoing studies are investigating the potential roles of VEGF-C/VEGFR-3 in cerebrovascular dynamics, fluid drainage, and cellular trafficking in mouse models of Alzheimer’s disease and multiple sclerosis.

We discovered the endothelial Tie (currently named Tie1) receptor tyrosine kinase in 1992. Today, it is known that angiopoietins (Ang1, Ang2, and Ang4), the ligands of Tie1 and Tie2, are essential for vascular stabilization following angiogenesis. We recently demonstrated how the Tie1/Tie2 angiopoietin receptor complex regulates vascular leakage during inflammation, how Ang2 blockade reduces neuroinflammation, and how Ang2 mutations are linked to human lymphedema. Furthermore, we showed that VEGF-C’s full lymphangiogenic activity requires autocrine Ang2 signaling in lymphatic endothelial cells. Given its unique role in vascular stability, the Ang-Tie signaling pathway represents a promising therapeutic target for diseases characterized by vascular dysfunction.

Antila, S, Chilov, D, Nurmi H, Li Z, Näsi A, Gotkiewicz M, Sitnikova V, Jäntti H, Acosta N, Koivisto H, Ray J, Keuters MH, Sultan I, Scoyni F, Trevisan D, Wojciechowski S, Kaakinen M, Dvořáková L, Singh A, Jukkola J, Korvenlaita N, Eklund L, Koistinaho J, Karaman S, Malm T, Tanila H, Alitalo K. Sustained meningeal lymphatic vessel atrophy or expansion does not alter Alzheimer’s disease-related amyloid pathology. Nat Cardiovasc Res 3: 474-491, 2024.

Brakenhielm E, Sultan I, Alitalo K. Cardiac Lymphangiogenesis in CVDs. Arterioscler Thromb Vasc Biol. 44:1016-1020, 2024.

Sultan I, Ramste M, Peletier P, Hemanthakumar KA, Ramanujam D, Tirronen A, von Wright Y, Antila S, Saharinen P, Eklund L, Mervaala E, Ylä-Herttuala S, Engelhardt S, Kivelä R, Alitalo K. Contribution of VEGF-B-Induced Endocardial Endothelial Cell Lineage in Physiological Versus Pathological Cardiac Hypertrophy. Circ Res. 134:1465-1482, 2024.

Anisimov A, Fang S, Hemanthakumar KA, Örd T, van Avondt K, Chevre R, Toropainen A, Singha P, Gilani H, Nguyen SD, Karaman S, Korhonen EA, Adams RH, Augustin HG, Öörni K, Soehnlein O, Kaikkonen MU, Alitalo K. The angiopoietin receptor Tie2 is atheroprotective in arterial endothelium. Nat Cardiovasc Res. 2:307-321, 2023.

Li Z, Antila S, Nurmi H, Chilov D, Korhonen EA, Fang S, Karaman S, Engelhardt B, Alitalo K. Blockade of VEGFR3 signaling leads to functional impairment of dural lymphatic vessels without affecting autoimmune neuroinflammation. Sci Immunol. 8:eabq0375, 2023.

Leppäpuska IM, Hartiala P, Suominen S, Suominen E, Kaartinen I, Mäki M, Seppänen M, Kiiski J, Viitanen T, Lahdenperä O, Vuolanto A, Alitalo K, Saarikko AM. Phase 1 Lymfactin® study: 24-month efficacy and safety results of combined adenoviral VEGF-C and lymph node transfer treatment for upper extremity lymphedema. J Plast Reconstr Aesthet Surg. 75:3938-3945, 2022.
Results of phase I clinical trial on adenoviral VEGF-C in lymphedema.

Korhonen EA, Murtomäki A, Jha SK, Anisimov A, Pink A, Zhang Y, Stritt S, Liaqat I, Stanczuk L, Alderfer L, Sun Z, Kapiainen E, Singh A, Sultan I, Lantta A, Leppänen VM, Eklund L, He Y, Augustin HG, Vaahtomeri K, Saharinen P, Mäkinen T, Alitalo K. Lymphangiogenesis requires Ang2/Tie/PI3K signaling for VEGFR3 cell-surface expression. J Clin Invest. 132(15):e155478, 2022
This study explains the mechanism by which angiopoietin2 and Tie1 mutations cause lymphedema.

Leppänen VM, Brouillard P, Korhonen EA, Sipilä T, Jha SK, Revencu N, Labarque V, Fastré E, Schlögel M, Ravoet M, Singer A, Luzzatto C, Angelone D, Crichiutti G, D’Elia A, Kuurne J, Elamaa H, Koh GY, Saharinen P, Vikkula M, Alitalo K. Characterization of ANGPT2 mutations associated with primary lymphedema. Sci Transl Med 12: eaax8013, 2020.
Discovery of mutations in angiopoietin 2 growth factor gene in primary lymphedema patients

Antila S, Karaman S, Nurmi H, Airavaara M, Voutilainen MH, Mathivet T, Chilov D, Li Z, Koppinen T, Park J-H, Fang S, Aspelund A, Saarma M, Eichmann A, Thomas J-L, Alitalo K. Development and plasticity of meningeal lymphatic vessels. J Exp Med 214: 3645-3667, 2017.
Meningeal lymphatics develop postnatally and require continuous VEGF-C stimulation for maintenance.

Aspelund A, Antila S, Proulx ST, Karlsen TV, Karaman S, Detmar M, Wiig H, Alitalo K. A dural lymphatic vascular system that drains brain interstitial fluid and macromolecules. J Exp Med 212: 991-9, 2015.
Listed amongst the 10 Breakthroughs of 2015 by Science and as one of 10 Notable advances 2015 by Nature Medicine.

Aspelund A, Tammela T, Antila S Nurmi H, Leppänen VM, Zarkada G, Stanczuk L, Francois M, Mäkinen T, Saharinen P, Immonen I, Alitalo K. The Schlemm’s canal is a VEGF-C/VEGFR-3-responsive lymphatic-like vessel. J Clin Invest 124: 3975-3986, 2014.
Schlemm’s canal that regulates intraocular pressure is a target of the lymphangiogenic growth factor VEGF-C.

Jeltsch M, Jha SK, Tvorogov D, Anisimov A, Leppänen V-M, Holopainen T, Kivelä R, Ortega S, Kärpänen T, Alitalo K. CCBE1 enhances lymphangiogenesis via a disintegrin and metalloprotease with thrombospondin motifs-3-mediated vascular endothelial growth factor-C activation. Circulation 129: 1962-1971, 2014.
Discovery of the first protease that activates VEGF-C and the mechanism of its regulation by CCBE1.

Leppänen V-M, Tvorogov D, Kisko K, Prota AE, Jeltsch M, Anisimov A, Markovic-Mueller S, Stuttfeld E, Goldie KN, Ballmer-Hofer K, Alitalo K. Structural and mechanistic insights into VEGF receptor 3 ligand binding and activation. Proc Natl Acad Sci USA 110: 12960-12965, 2013.
Atomic resolution structure of the VEGF-C/VEGFR3 complex reveals a homologous receptor-receptor interaction site that is compatible with blocking antibody function (Tvorogov et al., 2010).

Tammela T, Zarkada G, Nurmi H, Jakobsson L, Heinolainen K, Tvorogov D, Zheng W, Franco CA, Murtomäki A, Aranda E, Miura N, Ylä-Herttuala S, Fruttiger M, Mäkinen T, Eichmann A, Pollard JW, Gerhardt H, Alitalo K. VEGFR-3 controls tip to stalk conversion at vessel fusion sites by reinforcing Notch signalling. Nature Cell Biol 13: 1202-1213, 2011.
The mechanism of ligand-independent VEGFR-3 function in blood vessel fusions.

Tammela T, Saaristo A, Holopainen T, Ylä-Herttuala S, Andersson LC, Virolainen S, Immonen I, Alitalo K. Photodynamic ablation of lymphatic vessels and intralymphatic cancer cells prevents metastasis. Sci Transl Med 3: 69ra11, 2011.
A new method to inhibit in transit/satellite metastasis.

Tvorogov D, Anisimov A, Zheng W, Leppänen V-M, Tammela T, Laurinavicius S, Holnthoner W, Heloterä H, Holopainen T, Jeltsch M, Kalkkinen N, Lankinen H, Ojala P, Alitalo K. Effective Suppression of Vascular Network Formation by Combination of Antibodies Blocking VEGFR Ligand Binding and Receptor Dimerization. Cancer Cell 18: 630-40, 2010.
These results indicate that VEGF receptor directed antibodies that inhibit ligand binding and receptor dimerization have additive or even synergistic effects.

D’Amico G, Korhonen EA, Waltari M, Saharinen P, Laakkonen P, Alitalo K. Loss of endothelial Tie1 receptor impairs lymphatic vessel development-brief report. Arterioscler Thromb Vasc Biol. 30: 207-9, 2010
First indication that the Tie1 receptor is involved in lymphangiogenesis.

V-M Leppänen, A Prota, M Jeltsch, A Anisimov, N Kalkkinen, T Strandin, H Lankinen, A Goldman, K Ballmer-Hofer and K Alitalo: Structural determinants of growth factor binding and specificity by VEGF-Receptor 2. Proc Natl Acad Sci, USA, 107: 2425-2430, 2010.
The structure of VEGF-C, and its complex with the main angiogenic receptor VEGFR-2.

Tammela T, Zarkada G, Wallgard E, Murtomäki A, Suchting S, Wirzenius M, Waltari M, Hellström M, Schomber T, Peltonen R, Freitas C, Duarte A, Isoniemi H, Laakkonen P, Christofori G, Ylä-Herttuala S, Shibuya M, Pytowski B, Eichmann A, Betsholtz C, Alitalo K. Blocking VEGFR-3 suppresses angiogenic sprouting and vascular network formation. Nature 454: 656-60, 2008.
This paper reveals a new mechanism involved in blood vessel sprouting and provides an additional target for angiogenesis inhibition.

Tammela T, Saaristo A, Holopainen T, Lyytikkä J, Kotronen A, Pitkonen M, Abo-Ramadan U, Ylä-Herttuala S, Petrova TV, Alitalo K. Therapeutic differentiation and maturation of lymphatic vessels after lymph node dissection and transplantation. Nature Medicine 13: 1458-66, 2007.
The first evidence that collecting lymphatic vessels can differentiate from lymphatic capillaries in adults and that VEGF-C gene therapy induces this process.

He Y, Rajantie I, Pajusola K, Jeltsch M, Holopainen T, Ylä-Herttuala S, Harding T, Jooss K, Takahashi T, Alitalo K. Vascular endothelial cell growth factor receptor 3-mediated activation of lymphatic endothelium is crucial for tumor cell entry and spread via lymphatic vessels. Cancer Res 65: 4739-46, 2005.
The mechanism of VEGF-C induced lymphatic sprouting towards as well as dilation of the draining lymphatic vessels, both contributing to lymphatic metastasis. These processes were blocked dose-dependently by inhibition of VEGFR-3.

Petrova TV, Kärpänen T, Norrmen C, Mellor R, Tamakoshi T, Finegold D, Ferrell R, Kerjaschki D, Mortimer P, Ylä-Herttuala S, Miura N, Alitalo K. Defective valves and abnormal mural cell recruitment underlie lymphatic vascular failure in lymphedema distichiasis. Nature Medicine 10: 974-81, 2004.
Mechanism of development of Lymphedema distichiasis.

Kärkkäinen MJ, Haiko P, Sainio K, Partanen J, Taipale J, Petrova TV, Jeltsch M, Jackson DG, Talikka M, Rauvala H, Betsholtz C, Alitalo K. Vascular endothelial growth factor C is required for sprouting of the first lymphatic vessels from embryonic veins. Nature Immunology 5: 74-80, 2004.
The results of this paper indicate that VEGF-C is the paracrine factor essential for lymphangiogenesis, and that both Vegfc alleles are required for normal lymphatic development.

He Y, Kozaki K, Kärpänen T, Koshikawa K, Ylä-Herttuala S, Takahashi T, Alitalo K. Suppression of tumor lymphangiogenesis and lymph node metastasis by blocking vascular endothelial growth factor receptor 3 signaling. J Natl Cancer Inst 94: 819-25, 2002.
Development of VEGFR-3 signaling inhibitor for suppression of tumor lymphangiogenesis and metastasis to regional lymph nodes.

Mäkinen T, Jussila L, Veikkola T, Kärpänen T, Kettunen MI, Pulkkanen KJ, Kauppinen R, Jackson DG, Kubo H, Nishikawa S-I, Ylä-Herttuala S, Alitalo K. Inhibition of lymphangiogenesis with resulting lymphedema in transgenic mice expressing soluble VEGF receptor-3. Nature Medicine 7: 199-205, 2001.
Demonstration that a soluble form of VEGFR-3 is a potent inhibitor of VEGF-C/VEGF-D signaling and lymphangiogenesis.

Mandriota SJ, Jussila L, Jeltsch M, Compagni A, Baetens D, Prevo R, Banerji S, Huarte J, Montesano R, Jackson DG, Orci L, Alitalo K, Christofori G, Pepper MS. Vascular endothelial growth factor-C-mediated lymphangiogenesis promotes tumour metastasis. EMBO J 20: 672-82, 2001.
Demonstration that VEGF-C-induced lymphangiogenesis mediates tumour cell dissemination and the formation of lymph node metastases.
Note the Acknowledgements:” The project presented in this manuscript was conceived and started in Helsinki, and the work is the result of an equal contribution from the laboratories in Helsinki, Vienna and Geneva, together with a major contribution from the Oxford group.” This project was thus started in 1995 in Dr. Alitalo’s laboratory.

Kärpänen T, Egeblad M, Kärkkäinen MJ, Kubo H, Ylä-Herttuala S, Jaattela M, Alitalo K. Vascular endothelial growth factor C promotes tumor lymphangiogenesis and intralymphatic tumor growth. Cancer Res 61: 1786-90, 2001.
These data show that VEGF-C facilitates tumor metastasis to the lymphatic vessels and that tumor spread is inhibited by blocking the interaction between VEGF-C and its receptor.

Kärkkäinen MJ, Saaristo A, Jussila L, Karila KA, Lawrence EC, Pajusola K, Bueler H, Eichmann A, Kauppinen R, Kettunen MI, Ylä-Herttuala S, Finegold DN, Ferrell RE, Alitalo K. A model for gene therapy of human hereditary lymphedema. Proc Natl Acad Sci USA 98: 12677-82, 2001.
First demonstration that growth factor gene therapy would be applicable to human lymphedema and provide a paradigm for other diseases associated with mutant receptors.

Kärkkäinen MJ, Ferrell RE, Lawrence EC, Kimak MA, Levinson KL, McTigue MA, Alitalo K, Finegold DN: Missense mutations interfere with VEGFR-3 signalling in primary lymphoedema. Nature Genetics 25: 153-159, 2000.
Heterozygous missense mutations of VEGFR-3 were shown to inactivate the tyrosine kinase and downstream gene activation in primary lymphedema, indicating that mutations interfering with VEGFR-3 signal transduction are a cause of primary lymphoedema.

Dumont, DJ, Jussila L, Taipale J, Lymboussaki A, Mustonen T, Pajusola K, Breitman M, Alitalo K. Cardiovascular failure in mouse embryos deficient in VEGF receptor-3. Science 282: 946-949, 1998.
This paper shows that VEGFR-3 has an essential role in the development of the embryonic cardiovascular system before the emergence of the lymphatic vessels.

Jeltsch M, Kaipainen A, Joukov V, Meng X, Lakso M, Rauvala H, Swartz M, Fukumura D, Rakesh KJ, Alitalo K. Hyperplasia of lymphatic vessels in VEGF-C transgenic mice. Science 276: 1423-1425, 1997.
First evidence that VEGF-C induces lymphangiogenesis.

Joukov V, Pajusola K, Kaipainen, Chilov DA, Lahtinen I, Kukk E, Saksela O, Kalkkinen N, Alitalo K. A novel vascular endothelial growth factor, VEGF-C, is a ligand for the Flt4 (VEGFR-3) and KDR (VEGFR-2) receptor tyrosine kinases. EMBO J 15: 290-298, 1996.
Isolation of the first ligand for VEGFR3.

Joukov V, Pajusola K, Kaipainen, Chilov DA, Lahtinen I, Kukk E, Saksela O, Kalkkinen N, Alitalo K. A novel vascular endothelial growth factor, VEGF-C, is a ligand for the Flt4 (VEGFR-3) and KDR (VEGFR-2) receptor tyrosine kinases. EMBO J 15: 290-298, 1996.
Isolation of VEGF-C, the first ligand for VEGFR3.

Kaipainen A, Korhonen J, Mustonen T, van Hinsbergh VWM, Fang G-H, Dumont D, Breitman M, Alitalo K. Expression of the fms-like tyrosine kinase 4 gene becomes restricted to lymphatic endothelium during development. Proc Natl Acad Sci 92: 3566-3570, 1995.
First evidence that VEGFR3 mediated signals are selective for lymphatic vessels in adults.

Partanen J, Armstrong E, Mäkelä TP, Korhonen J, Sandberg M, Renkonen R, Knuutila S, Huebner K, Alitalo K. A novel endothelial cell surface receptor tyrosine kinase with extracellular epidermal growth factor homology domains. Mol Cell Biol 12: 1698-1707, 1992.
Discovery of the endothelial Tie receptor (later renamed Tie1)

Aprelikova O, Pajusola K, Partanen J, Armstrong E, Alitalo R, Bailey SK, McMahon J, Wasmuth J, Huebner K, Alitalo K. FLT4, a novel class III receptor tyrosine kinase in chromosome 5q33-qter. Cancer Res. 52(3):746-8, 1992.
Discovery of vascular endothelial growth factor receptor 3.