Research team ups the ante with development of woven blood vessels

A lot of people were skeptical when two young California-based researchers set out more than a decade ago to create a completely human-derived alternative to the synthetic blood vessels commonly used in dialysis patients. Since then, they've done that and more. "There were a lot of doubts in the field that you could make a blood vessel, which is something that needs to resist pressure constantly, 24-7, without any synthetic materials in it," explains Nicolas L'Heureux, a co-founder and the chief scientific officer of Cytograft Tissue Engineering Inc. "They didn't think that was possible at all." But they were wrong. Cytograft, which L'Heureux and Todd McAllister co-founded in 2000, has indeed developed vessels that are "completely biological, completely human and living, which is the Cadillac of treatments ... and it seems to work really well," L'Heureux says. First the team created blood vessels from patients' own skin cells. Then, in June, the company announced that three dialysis patients had received the world's first lab-grown blood vessels made from skin cells from donors, which eliminates the long lead time needed for making vessels from a patient's own cells. And now Cytograft has developed a new technique for making human textiles that promises to reduce the production cost of these vessels by half. L'Heureux presented his team's latest findings at the annual meeting of the American Association of Anatomists, which is being held in conjunction with the Experimental Biology 2012 meeting in San Diego.Cytograft's new approach builds on what already has been proved successful. In 2005, the team began extracting fibroblasts from patients' own skin, cultured those cells into thin sheets, rolled up those sheets, cultured them some more so that they would fuse together, and implanted the lab-grown cylindrical vessels. The vessel-growing process was lengthy, at about seven months, but, because the vessels were derived from the patients' own cells, the implants were easily accepted by the patients' bodies, and they held up to the rigors of dialysis, which requires repeated punctures with large-gauge needles. Then the researchers created allogeneic vessels - ones grown from donor cells - with the hope that they were laying the foundation for an off-the-shelf stockpile of 100 percent human replacement parts. "By combining these two methods we could make something that is allogeneic, cheaper to produce, and that you could store forever, meaning that the clinician can pull it off the shelves whenever they want," L'Heureux explains. "If it is frozen and allogeneic, that is kind of the homerun." Those donor-based vessels were implanted into three patients in Poland, and they have performed well with no signs of rejection. That accomplishment was a big one, from a manufacturing standpoint, L'Heureux says, because "it is very, very costly to segregate all the patients' cells at all the steps with all the material and all the media and the culturing zones."