Abstract P037: Viable Autologous Umbilical Cord Patch for Aortic Reconstruction in Newborn Piglets

Abstract

Background: Aortic surgery in neonates often uses a patch of cryopreserved allogeneic artery. Drawbacks include alloimmunization in infants who may later need heart transplant. We hypothesized that the umbilical cord (UC) may be a non-immunogenic, viable vascular patch suited to neonatal aortic surgery. This was evaluated in ex vivo studies of human UC, and in vivo study in piglets. Method: Human UC (20) were collected after vaginal birth, were dilated and measured. Swab cultures were taken. For final culture UC was put in Thiol, and held for 4 wk. Disinfection was in dilute hypochlorite for 30 sec to 5 min. UC segments were stored in HTK solution with antibiotic/antifungal agent at 4 deg for 3 to 9 d. Samples were fixed for histology. At 9 d, samples were put in tissue culture to check viability. Then, 18 farm piglets in three litters were delivered by hysterotomy. Each UC was sanitized, cultured, and stored as described for human UC. At 7 d, each piglet underwent laparotomy. A defect made in the abdominal aorta was patched with autologous UC or with PTFE. Piglets were killed after 8 and 12 wk to examine the patched aorta. Result: Human UC diameter was 8-11 mm. Cultures of 5 UC in Dakins for 30 sec, 1, 2, 3, and 4 min were all negative. All later UC were treated for 30 sec only. One culture from one UC segment after 9 d was positive; final culture from this UC wwas negative. Histology did not differ at 9 d from day of delivery (n=3). Cells grew from 9 d UC in tissue culture (n=2). Piglet UC at 7 d also held viable cells. Piglet UC patch worked well in surgery. Hemostasis was rapid with UC, and was longer with PTFE. Three piglets were killed before 8 wk due to hernia. There was no dehiscence, infection, or aneurysm in either group. UC-patched aorta lengthened 114%, PTFE grew 21%. Patched aorta was non-stenotic in both groups, 92% of normal in UC vs. 95% in PTFE. By histology the UC did not remain viable, but calcified and broke into fragments. Beneath both UC and PTFE patches, fibroblast proliferation spanned the aortic defect. In UC piglets, this layer enlarged after UC fragmentation. Conclusion: UC can be sterilized and kept viable after vaginal birth . UC patch worked well for repair of an aortic defect in piglets, but UC viability and growth were not seen. UC needs further study before trial in human aortic surgery.