One of the biggest challenges in replacing damaged organ tissue is the regrowth of blood vessels, arteries and veins. Scientists have been working to overcome this challenge by developing innovative ways to engineer vascular networks.

Brady et al. are using cords of endothelial cells in tissue grafts to guide the assembly of blood vessels after grafting, like the way vines grow over a trellis.

“We previously developed a method that guides the body to build blood vessels in artificial organs after they are implanted in the mouse abdomen,” said author Kelly Stevens. “We were surprised that when we tried to use this same strategy on rat hearts, we saw very different results.

“We think this study highlights the need for us to closely consider ‘host’ biology – that is the animal or person the tissue is implanted in as well as the location of the implant in the body – when we are developing artificial organs.”

The authors grafted bioartificial tissue patches onto the hearts of rats and harvested them at 1, 3, 7 and 14 days later. By day 3, the authors noticed extensive emerging vasculature. By day 7, the vasculature was able to be filled with liquid.

The researchers witnessed an increase in inflammation, which they believe might lead to patch degradation, collagen deposition and loss of patterning. However, they discovered the engraftment still occurred in patches containing the endothelial cords.

In the future, the authors intend on researching how the location of the graft and/or species of the animal affects the development of vasculature in bioartificial tissue.

Source: “Guided vascularization in the rat heart leads to transient vessel patterning,” by Eileen L. Brady, Mitchell A. Kirby, Emily Olszewski, Parker Grosjean, Fredrik Johansson, Jennifer Davis, Ruikang K. Wang and Kelly Stevens, APL Bioengineering (2020). The article can be accessed at