O10 - Digital Light Processing (DLP)-mediated Control of Paracrine Interactions for Vascular Assembly

Saturday, October 11, 2025

10:00 AM - 11:00 AM PDT

Location: Exhibit Hall F, G & H

Presenting Author(s)

Abigail D. Gregorio

Student
California State University Long Beach
Seal Beach, California, United States

Co-Author(s)

NB

Nathaniel C. Burmas

Graduate Student
University of California, Irvine
Irvine, California, United States

Primary Investigator(s)

Quinton Smith

Assistant Professor
University of California, Irvine
Irvine, California, United States

Introduction: : Vasculogenesis, the formation of new blood vessels, is a current challenge for the survival and function of organoids and engineered tissues, both in vitro and post-implantation. The lack of adequate vascularization prevents proper blood flow to deeper tissue, leading to hypoxia, nutrient deficiencies, and subsequent cell death. An approach to improving vascularization involves stromal cells, a common cell type in connective tissue that secretes a rich array of growth factors, cytokines, and extracellular matrix proteins. By leveraging the natural cues of stromal cells and allowing them to interact with endothelial cells upon vessel formation, our approach aims to recapitulate the intricate cellular interactions and microenvironment present in vivo. We hypothesize that distal cues, caused by the diffusion of stromal factors, influence vessel formation in a high-throughput multimaterial environment towards the control of vasculogenesis.

Materials and

Methods: : Fibrin gels and gelatin-methacrylate (GelMA) constructs are initially evaluated for the viability of encapsulated cells and diffusivity using FITC-dextran. Multi-material test prints are then used to evaluate vasculogenesis based on two variables: distance and cell amount. To create multi-material test prints, we encapsulate human dermal fibroblasts (HDFs) into a cube-shaped 7.5% GelMA construct with 0.1% LAP via digital light processing (DLP)-based bioprinting. Next, 2.5 mg/mL fibrin gels with encapsulated human umbilical vein endothelial cells (HUVECs) are added around the constructs. The effects of distance on vasculogenesis are tested by creating prints with the GelMA cubes placed 1, 2, or 3 mm apart, seeding at a density of 1 million human dermal fibroblasts (HDFs)/mL. The effects of cell amount on vasculogenesis are tested by creating GelMA cubes with 0, 1 million, or 2 million HDFs/mL at 2 mm apart. After 3 days, the prints are immunostained for phalloidin, DAPI, and CD31, a protein found on endothelial cells that line blood vessels.

Results, Conclusions, and Discussions:: The incorporation of HDFs led to significant vessel formation within the constructs after 3 days, denoting that the diffusion of stromal factors is crucial in orchestrating vasculogenesis. Such stromal factors include vascular endothelial growth factor (VEGF), stimulating endothelial cell proliferation and migration. The GelMA cubes with no fibroblasts led to limited HUVEC capillary formation, highlighting that the presence of HDFs is necessary for vascular remodeling. For the distance test trials, the GelMA cubes placed 2 mm apart promoted faster vessel formation compared to other distances. We observed fibroblast migration into the fibrin gel, increasing proximity between the cell types and allowing a greater amount of stromal cues to be received by the HUVECs. This may also be attributed to the migration of fibroblasts to promote vascular stability. Future work focuses on further investigating the mechanical effects of vessel network creation. Collectively, this work contributes to the advancement of vascular assembly in engineering tissues through paracrine interactions and mechanical effects.

Acknowledgements and/or References (Optional): :