Special Poster Session Biofabrication
One of the fundamental need in tissue engineering to fabricate tissues/organs is the proper vascularization that ensures a sufficient blood supply of tissues with nutrients and oxygen. So far, the in vitro generation of hierarchically organized functional vascular networks has not been achieved yet.
Aim of the project is to biofabricate hierarchically organized vascular structures with the typical three-layered in large and middle sized vessels and two layered wall structure in vessels of microcirculation using vascular wall-resident stem cells (VW-SCs) or human induced pluripotent cells (hiPSCs) that were pre-differentiated into mesodermal progenitor-like cells. Both VW-SCs and induced mesodermal progenitor cells have the capacity to deliver mature cell types that are needed for morphogenesis of the vascular wall such as endothelial cells, smooth muscle cells, pericytes as well as fibroblasts or mesenchymal cells(1). Second essential biofabrication components are advanced printing techniques and matrix material e.g. hydrogels. To bioprint the vascular structures we used two potential approaches, namely standard extrusion and core-shell printing. Bioink was prepared by mixing hydrogel with cells and was bioprinted by using the two approaches. Hydrogel was also supplemented with extracellular matrix components such as Collagen I, Collagen IV or Laminin to support cellular activities and morphogenetic events.
After optimization the printing parameters, cell numbers and cell types, printed bioink were cultured within differentiation medium over up to several weeks under adding VEGF to the culture. In the fallowing day of culturing, especially within collagen-I supplemented hydrogel; cell diffusion and cell elongation were observed. It was determined that cell proliferation, interactions and differentiation depend on the number of initially printed cells. The cells survived within the gel for weeks, entered differentiation and morphogenesis resulting in formation of cell cords after bioprinting. In-depth analyses revealed that the formation of vessel-like structures with lumen formation.