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Liposuction can provide the raw materials for growing new small-diameter blood vessels in the lab, researchers found.
Adult stem cells extracted from one's own fat tissue, then cultured into sheets, and rolled into tiny vessels performed as well as natural vessels on elastic contractility, reported Matthias Nollert, PhD, of the University of Oklahoma School of Chemical, Biological, and Materials Engineering in Norman, Okla., and colleagues.
The engineered vessels still need some work to withstand as much pressure as a native vessel can take without bursting, the group reported at the American Heart Association's Basic Cardiovascular Sciences meeting in New Orleans.
"There's a lot of promise but we're still very early on," Nollert told ľֱ in a phone interview.
The internal mammary arteries provide the best conduit for bypassing blocked arteries in the heart, but the limited supply of autologous vessels isn't always enough to cover multivessel disease or subsequent procedures.
Synthetic grafts are an option but only for large-diameter vessels 6 mm or larger because of patency problems in smaller vessels.
"Tissue engineering has the potential to overcome these limitations by producing a readily-available vascular graft completely from biological material," the researchers pointed out.
Engineered vessels may be a good solution for children too, whose growing organs need vessels that can grow with them.
A bypass graft engineered from a deceased-donor vein and the patient's own bone marrow stem cells was recently shown to work for a girl with portal vein obstruction.
If the proof-of-concept results with the liposuction-derived stem cells are durable in vivo, it could be an easier route to engineered vessels than the painful bone-marrow procedure for the typically older, sicker heart disease population.
Nollert explained that they needed only a couple tablespoons of fat from a "nip-tuck" procedure in the plastic surgeons' office to provide enough stem cells to seed a new vessel.
The stem cells, which are associated with the extensive vasculature in the fat rather than the fat itself, are then differentiated into smooth muscle cells in the lab.
They are "seeded" onto a flat sheet of decellularized collagen from discarded placenta, which Nollert noted is an FDA-approved material.
Once the patients' cells colonize the scaffold, it's rolled into a thin tube of the desired diameter. All told, the process takes 3 to 4 weeks.
The thickness and architecture of the engineered vessel matched that of a porcine coronary artery in a histological analysis. It also performed better than the porcine vessel for elasticity in a tensile strength test.
"But the burst pressure is still too low," Nollert said. "We get burst pressures about 150 mm Hg, and native tissue is around 1,000 mm Hg."
The problem appears to be that the layers of the rolled-up vessel aren't adhering well to one another, he explained.
"We're trying out some new ideas using tissue glue or other types of glue to hold these layers together," he said. "What we really have right now is a neat idea without having the data to show that it's going to work."
The group said it hopes to move into testing the vessels in animals soon.
From the American Heart Association:
Disclosures
The study was funded by the American Heart Association. The human adipose-derived stem cells were supplied by Pennington Biomedical Research Center in Baton Rouge, La.
The researchers reported no conflicts of interest.
Primary Source
American Heart Association Basic Cardiovascular Sciences Scientific Sessions
Source Reference: Brennan JA, et al "Development of a human tissue-engineered blood vessel from adipose-derived stem cells" BCVS 2012; Abstract 360.