Techniques and assays for the study of angiogenesis

Platelet lysate-based pro-angiogenic nanocoatings

Human platelet lysate (PL) is a cost-effective and human source of autologous multiple and potent pro-angiogenic factors, such as vascular endothelial growth factor A (VEGF A), fibroblast growth factor b (FGF b) and angiopoietin-1. Nanocoatings previously characterized were prepared by layer-by-layer assembling incorporating PL with marine-origin polysaccharides and were shown to activate human umbilical vein endothelial cells (HUVECs). Within 20 h of incubation, the more sulfated coatings induced the HUVECS to the form tube-like structures accompanied by an increased expression of angiogenic-associated genes, such as angiopoietin-1 and VEGF A. This may be a cost-effective approach to modify 2D/3D constructs to instruct angiogenic cells towards the formation of neo-vascularization, driven by multiple and synergistic stimulations from the PL combined with sulfated polysaccharides.

STATEMENT OF SIGNIFICANCE

The presence, or fast induction, of a stable and mature vasculature inside 3D constructs is crucial for new tissue formation and its viability. This has been one of the major tissue engineering challenges, limiting the dimensions of efficient tissue constructs. Many approaches based on cells, growth factors, 3D bioprinting and channel incorporation have been proposed. Herein, we explored a versatile technique, layer-by-layer assembling in combination with platelet lysate (PL), that is a cost-effective source of many potent pro-angiogenic proteins and growth factors. Results suggest that the combination of PL with sulfated polyelectrolytes might be used to introduce interfaces onto 2D/3D constructs with potential to induce the formation of cell-based tubular structures.

Studies on the Tumor Vasculature and Coagulant Microenvironment

Angiogenesis represents one aspect in the complex process that leads to the generation of the vascular tumor stroma. The related functional constituents include responses of endothelial, mural, bone marrow-derived, and resident inflammatory cells as well as activation of coagulation and fibrinolytic systems in blood. Multiple molecular and cellular effectors participate in these events, often in a tumor-specific manner and with changes enforced through the microenvironment, genetic evolution, and responses to anticancer therapies. To capture various elements of these interactions several surrogate assays have been devised, which can be mechanistically useful and are amenable to quantification, but are individually insufficient to describe the underlying complexity and are best used in a targeted and combinatorial manner. Below, we present a survey of angiogenesis assays and experimental approaches to analyze vascular events in cancer. We also provided specific examples of validated protocols, which are less described, but enable the straightforward analysis of vascular structures and coagulant properties of cancer cells in vivo and in vitro.