Browsing by Subject "VEGF-C"

Vascular endothelial growth factor C (VEGF-C) is the most studied of the growth factors that control the growth of lymphatic vessels (lymphangiogenesis) and belongs to the same VEGF family as VEGF-A, which controls the growth of blood vessels. The growth of blood vessels and lymphatic vessels is centrally related to the pathophysiology of several cancers that form solid tumours and wet macular degeneration. Unlike VEGF-A, VEGF-C is not currently (2023) a target molecule of any approved drugs, but in clinical trials in the indications mentioned above, combining a VEGF C inhibitor with VEGF-A inhibitors has provided better results than VEGF-A inhibitor monotherapy. The study's objective was converting a phage display library containing single-chain antibody variable fragments (scFvs) screened against VEGF-C into full IgG class antibodies. The scFvs had shown a binding affinity towards the human, mouse, or both VEGF-C variants. The DNA sequences of the best binders of the library had previously been cloned into pLK06H plasmids. The scFvs comprise the variable region of the light and heavy chain (VL and VH) but do not contain the constant regions of the antibody (CL and CHx). Using single-chain antibody fragments as drugs is limited because, in most indications, better stability of whole antibodies, lower immunogenicity, and a longer half-life enabling less frequent dosing is desirable. In addition, the Fc part of whole antibodies often mediates the drug effect, such as complement activation, and whole antibodies are also used as research tools. Secondly, the study aimed to investigate how changing the antibody format affects the binding affinity. To produce whole antibodies, original DNA sequences of pVitro-trastuzumab-IgGk1 plasmid encoding VH and VL regions were replaced with new VH and VL sequences from the phage display library. Several recombinant DNA technology methods were utilised, but the most crucial method was the commercially available NEBuilder HiFi DNA Assembly, which enabled the seamless joining of several DNA fragments into a recombinant DNA molecule in a single-tube reaction. The cloning workflow proved uncertain, as only one constructed antibody production plasmid was sufficiently amplified and expressed in bacterial and mammalian cell cultures. Suboptimal overlapping of DNA fragments and insufficient competence of the bacterial strain used in the transformation were probable bottlenecks. Therefore, as such, the method is not suitable for use on a large scale to convert single-chain antibody fragments into whole antibodies. Also, binding tests were not performed. However, the work done and the antibody production plasmid built is a good basis for further optimisation of the method. In the optimisation, attention should be paid, especially to the quality of the DNA primers and the competence of the bacterial cell line. Also, alternative cloning methods, such as restriction enzymes and ligases, could be used instead of the NEBuilder HiFi DNA Assembly.

Lymphatic vascular system consists of lymphatic capillaries and collectors existing alongside a circulatory system of blood vessels. The lymphatic system is responsible of draining tissue fluids, trafficking of immune cells and intestinal absorption of dietary lipids. Most of the lymphatic networks develop during embryogenesis, but lymphangiogenesis (the growth of new lymphatic vessel, LV) occurs also in adult tissues, for example, during inflammation. Exposure to vascular endothelial growth factor C (VEGF-C) initiates lymphatic endothelial cell (LEC) proliferation and sprouting of LVs. In lymphangiogenesis, leading tip cell migrates and samples the surrounding environment while stalk cells proliferate and are responsible of LV elongation and extension. Since polarity of dividing cells and subsequent daughter cell positioning possess a key role in morphogenesis of tubular organs, such as lungs, kidney or blood vessels, a regulation of daughter LEC positioning after cell division might determine how LVs elongate and widen. The aim of this study was to investigate the LV network enlargement and daughter LEC positioning during growth of LVs and to reveal potential contributing factors guiding the cell positioning (such as cell polarity). In this study, the LV network of mouse ear pinna was used as a model tissue to investigate LV network enlargement, daughter LEC positioning and LEC polarity in growing LVs. Characterization of mitotic cells in developing LV network revealed that LEC proliferation occurs throughout the entire length of LVs in the network. To investigate LEC polarity in developing and mature LVs, I analysed Golgi and nuclear polarity of tip and stalk LECs. I found that whereas LECs during development are polarized and oriented along the long axis of LV, there is more variation in the direction of LEC polarity in relation to LV long axis in mature LV. This observation raised a question whether changes in the cell polarity were reflected to cell positioning, hence I analysed the positioning of daughter LECs by forcing LECs to the cell cycle with VEGF-C. These results indicated cell-level mechanisms that may contribute to LEC positioning in lymphangiogenesis. My finding provides an efficient tool for further research due to its suitability for monitoring proliferating LECs and studying causative factors affecting LEC proliferation and positioning. Future experiments with real-time imaging will reveal more about lymphangiogenesis process and provide insights into the role of lymphatic vasculature in conditions such as inflammation-related lymphedema or anti-tumor immunity in cancer.

Selvitin tutkimuksessani VEGF-C:n ja RET:n vaikutusta hiiren enterisen hermoston ja imusuoniston kehitykseen. Yhden ja kahden VEGF-C-alleelin puutos johti neuronien määrän vähenemiseen jejunumissa ja koolonissa. RET-alleelien puutos vähensi myös neuronien määrää ja kahden puutos esti neuronien kehittymisen. VEGF-C ja etenkin RET-muuntogeenisiä alkioita oli myös hiiripoikueissa vähemmän kuin Mendelistisen jakauman perusteella voisi olettaa. Tämä viittaa lisääntyneeseen kuolleisuuteen in utero. Myös ihon karvatuppia oli RET-homogeenisissä vähemmän kuin villityyppisissä. Lisäksi selvitin mitkä vasta-aineet soveltuvat käytettäväksi suolten erityyppisissä vastaainevärjäyksissä