VEGFA dependent endothelial lumen formation in scaffold-free tissue engineering: a hybrid in vitro and in silico approach to improve vascularization of tissue: Spheroid simulation data

Vascularization is a tightly regulated process involving a complex interplay of multiple bio-signaling events. Among these events, lumen formation is a crucial rate-limiting step in successful anastomosis of tissue engineered constructs in a host. We have developed scaffold-free endothelial-fibroblast based constructs with preformed microvessel networks that are a promising approach to rapid host-implant anastomosis. However, rapid formation of a continuous endothelial lumen within the microvessels remains elusive. We propose that pretreatment of these constructs with vascular endothelial growth factor A, a potent proangiogenic molecule, can improve large caliber lumen formation within constructs during in vitro self-assembly.

Here, we present a hybrid in vitro and in silico approach to evaluating endothelial-fibroblast spheroid self-assembly and the effects of VEGF-A on lumen formation. Our VEGF-A dosing experiments ultimately demonstrated that our endothelial cells responded to VEGF-A by increased clustering tendency and hollow lumen formation. This behavior was coincident with an increase in polarization markers as well as a time and dose dependent increase in diameter of lumens. We used these observations to develop a simulation model using the Cellular Potts framework, a modeling framework that is well-adapted to tissue self-assembly. The model explores how changes in interfacial energy costs between cell types in our model as well as changes in basic cell parameters such as response to VEGF-A, growth and proliferation can alter dynamics of lumen formation within a construct. From our model, we ran a series of simulated experiments to generate tissues with an optimal distribution of large caliber vessels. Our analysis of the resulting regression model identified several statistically significant modifiable factors that could be mapped back to potential spheroid pretreatment strategies. These strategies could augment VEGF-mediated lumen formation and provide rationale for alterations in the design of our constructs.

Methods
Simulations were run using CompuCell 3D version 3.7.5. Software available from Glazier et. al in  https://compucell3d.org/

CompuCell 3D is an open source software developed and described in:

Multi-Scale Modeling of Tissues Using CompuCell3D – M. Swat, Gilberto L. Thomas, Julio M. Belmonte, A. Shirinifard, D. Hmeljak, J. A. Glazier, Computational Methods in Cell Biology, Methods in Cell Biology 110: 325-366 (2012)

Main simulation files are available in <Simulation_Code> folder

Run the .cc3d files in each run folder (e.g. Polar1). The final outputs during each run are stored as .vtk files in <Simulation_Lattice> Folder.

A comprehensive ReadMe file is included in dataset.