Z17 - Exploring the Effects of Soluble Growth Factors and Inhibitors on Vasculogenesis

Saturday, October 11, 2025

10:00 AM - 11:00 AM PDT

Location: Exhibit Hall F, G & H

Presenting Author(s)

Vidhi Patel

Undergraduate Researcher
University of Alabama at Birmingham
McComb, Mississippi, United States

Co-Author(s)

Vaishali Bala, MEng

Graduate Research Assistant
University of Alabama at Birmingham
Birmingham, Alabama, United States

Primary Investigator(s)

MK Sewell-Loftin

Assistant Professor
University of Alabama Birmingham, Alabama, United States

Introduction: : Vasculogenesis is the formation of blood vessels de novo, as opposed to angiogenesis which is the growth of new vessels from existing structures. Understanding how growth factors and mechanical cues interact to drive vasculogenesis could help improve tissue engineering strategies. Our project focused on the effects of various growth factors, alone and in combination with stromal mechanical stimulation, on blood vessel growth. Three growth factors, epidermal growth factor (EGF), stromal cell-derived factor 1 (SDF-1), and vascular endothelial growth factor (VEGF) were investigated. VEGF plays a primary role in blood vessel growth as it stimulates endothelial cells to grow and migrate, which are the cells that line blood vessels. EGF is a ligand that has also been shown to promote cell proliferation and migration. SDF-1 is a signaling protein involved in angiogenesis, specifically directional migration, and has also been shown to increase VEGF expression. The objective of this study was to quantify and determine the effects of various growth factors and contractility inhibitors on the rate of vasculogenesis. Based on a better understanding of these growth factors, an appropriate concentration will be determined for use in a control microtissue model to produce a more relevant 3D microtissue model to further explore vasculogenesis in an in vitro model.

Materials and

Methods: : A 3D microtissue model was used to co-culture hTERT immortalized endothelial cells (HT2s) with normal human dermal fibroblasts (NHDF) or normal human lung fibroblasts (NHLF) to promote the development of blood vessels. These models were cultured for 7 days and growth factors or contractility inhibitors factors were added to the media on day 2. To test the effects of growth factors, media with EGF (25ng/mL), SDF-1 (100ng/mL), or VEGF (25ng/mL) were used. For the combination groups of growth factors, the concentrations of growth factors remained the same. Control samples were HT2 co-cultured with fibroblasts in EGM-2 media without additional growth factors. To test the inhibition of fibroblast contractility, media with verteporfin was used (3µM), or with dimethyl sulfoxide (DMSO) as a vehicle control. On day 7, the models were fixed and stained for DAPI and CD31. AngioTool was utilized to quantify blood vessel growth. The data was normalized to the control HT2 only group, and a Kruskal-Wallis and post-hoc Dunn’s test was performed to determine significance.

Results, Conclusions, and Discussions:: Vascular density was quantified using the ratio of the total length of vessels within an area (Fig. 1a). The microtissue model with HT2s only degraded in the presence of VEGF; this may be due to the acceleration of vasculogenesis with the addition of VEGF, resulting in the matrix being overtaken by the overproliferation of the cells. A significant increase in vascular growth was observed with the combination of all growth factors compared to each factor treated individually, including the control for the HT2+NHDF cocultures (Fig. 1b). This combination of growth factors seems to have a greater effect than any individual growth factor. There was a significant increase in vascular density in the HT2+NHLF cocultures compared to the HT2+NHDF cocultures when treated with SDF-1. This suggests that mechanical activity in combination with SDF-1 has an effect on vascular growth, as NHLFs are more mechanically active than NHDFs. An increase was also observed in the HT2+NHLF cocultures with SDF-1+VEGF when compared to EGF, suggesting that SDF-1+VEGF increases proliferation in highly mechanically active lines as opposed to SDF-1. Through immunofluorescence, it can be observed that verteporfin decreases in long-range vessel structure, though it does not appear to decrease overall CD31 expression (Fig. 2). This finding was unexpected, and it may demonstrate that YAP mechanotransduction is only partially involved in regulating endothelial cell behaviors related to vascular growth. Future directions involve the introduction of controlled mechanical strains to stimulate and control vessel growth. Following this, experiments based on these results will be replicated in microfluidic models to explore angiogenesis and vasculogenesis and further understand the formation of vasculature for building better vascularized tissue engineering scaffolds.

Acknowledgements and/or References (Optional): :