A finding that has significant implications for the treatment of heart and kidney disorders was reported by the McGowan Institute faculty member David Vorp, PhD, associate professor of surgery and bioengineering, University of Pittsburgh School of Medicine.
Team leader Vorp and fellow investigators have engineered artificial blood vessels from muscle-derived stem cells (MDSC) and a biodegradable polymer that exhibit extensive remodeling and remain free of blockages when grafted into rats. They developed their vascular graft by “bulk seeding,” or spraying, MDSCs inside a biodegradable porous, tubular polyester urethane scaffold using a rotational vacuum seeding device.
After culturing their vascular constructs for 7 days, the investigators then implanted them in the abdominal aortas of rats 8 weeks before performing tests to determine how well the grafts had performed. The cell-seeded constructs showed a significantly higher blockage-free rate than unseeded controls (55 percent versus 0 percent). In addition, at 8 weeks, there was an extensive remodeling of the MDSC-seeded polymer by surrounding tissue, exhibiting tissue formation that is consistent with a mature artery.
According to Dr. Vorp, these findings in a rat demonstrate the feasibility of developing MDSC-seeded tissue-engineered vascular grafts for eventual human application. “The next step is to demonstrate the use of the tissue-engineered blood vessel in a larger animal model, such as a pig, which has a coagulation system more similar to that in humans. The advantage of our approach is that the graft could utilize the patient’s own stem cells and be ready for implantation almost immediately or, at most, after a relatively short culture period. This suggests that we could make these available ‘off-the-shelf,’ which is an essential element for clinical translation,” he explained.
Illustration: McGowan Institute for Regenerative Medicine.