UT Austin researchers have discovered a method and model to facilitate the growth of blood vessels using powerful human induced pluripotent stem cells, which will advance the field of regenerative medicine.

TissueEngineeringPartAkey

Vascular networks formed in the hydrogels (shown in gray) were imaged on a spinning disc confocal. The resulting 3D volumes were skeletonized (red) and then a nodal analysis was performed to evaluate the overall size and connectivity of the network.

A new paper in Tissue Engineering Part A describes a way to prompt the growth of cells that make up blood vessels, known as endothelial progenitors, in an in vitro 3D environment that mimics the human body as well as a method for quantifying results. A second paper in Journal of Visual Experiments gives an in-depth description of the materials and process of the experiment, so that other researchers can use the same computational pipeline that can quantify the potential to grow vasculature.

Janet Zoldan, assistant professor in biomedical engineering, and her lab work with human induced pluripotent stem cells (IPSCs). IPSCs are powerful patient-derived stem cells that can be differentiated into any specific type of cell in the body. For this study, researchers were specifically interested in differentiating IPSCs into endothelial cells in a three-dimensional environment.

Understanding how to grow vasculature from IPSCs could lead to beneficial impacts in treating patient-specific ischemic diseases. Vasculature grown from a patient’s own cells could be used to replace damaged vessels.

While there have previously been many models showing how IPSCs may grow into endothelial cells two-dimensionally, e.g., on a cell culture dish, no one has rigorously tested vascular progenitor growth in a three-dimensional environment. For this study, researchers worked with collagen as a three-dimensional structure because that material is a major component in the human extracellular matrix.

“In the body, vessels grow in a 3D environment. A 2D-model is less likely to give us reliable information because it doesn’t mimic what’s happening in the body,” says the papers’ lead author Cody Crosby, a fourth-year doctoral student.

The goals of the study were to create a simple protocol to seeed IPSC-dervived vascular progenitor cells in collagen and then perform a quantitative analysis so that researchers across labs and groups, and even researchers within the same group could easily compare results.

“Researchers use different platforms, some of which are heavily pay-walled, or if they are free, often not accurate,” says Crosby. “If someone reports statistics for their vasculature, it’s hard to tell how it compares to another researcher’s.”

Creating a free, open-source computational pipeline will give researchers a uniform way to measure results, which should lead to more collaborative efforts in vascular regeneration.

The next steps for researchers include performing similar experiments with different 3D environments, such as a modified hyaluronic acid to determine more about which properties facilitate endothelial cell growth.

This work was supported by the American Heart Association and the National Institute of Biomedical Imaging and Bioengineering (NIBIB) of the National Institutes of Health.