Editors' ChoiceTissue Engineering

The placenta as a source of vascular grafts

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Science Translational Medicine  13 Jun 2018:
Vol. 10, Issue 445, eaau0467
DOI: 10.1126/scitranslmed.aau0467


Decellularized human placental arteries show potential for use as small-diameter vascular grafts in a rodent model.

Complications arising from vascular occlusion are one of the leading causes of death worldwide. Autologous vascular grafts currently used in surgery have limited success due to poor long-term patency rates, and efforts to develop small-diameter vascular grafts from synthetic materials have been hampered by biomechanical property mismatch, thrombogenicity, and microbiological contamination. There is a critical need for alternative engineered small-diameter vascular grafts.

Now, Schneider and colleagues have demonstrated that decellularized blood vessels from human placenta have potential to be used as vascular replacement materials. The researchers compared two detergent protocols to decellularize arteries extracted from human placental chorion (the outer membrane that surrounds the amnion) that were then crosslinked with heparin to reduce thrombogenic response. To investigate biocompatibility, the decellularized vascular grafts were implanted subcutaneously in a nude rat model. Host cells started to infiltrate into the area one week after implantation and the tubular implants were structurally degraded after one month, without evidence of an inflammatory reaction. The authors attributed this to the lack of stimulating effects of blood perfusion. Next, decellularized vascular grafts were tested as aortic implants in rats to evaluate surgical applicability, cell migration, and early graft remodeling. Grafts decellularized using either detergent protocol showed 100% patency rates one month after implantation, and all of the grafts were fully integrated into the surrounding tissue with no evidence of severe foreign body reaction or systemic inflammation. Magnetic resonance imaging confirmed that grafts did not dilate, occlude, or show luminal narrowing in any animals. Scanning electron microscopy showed reendothelialization of the matrix lumen, and immunofluorescent staining showed remodeling of the vascular muscle tissue by the graft-infiltrating cells. Histological examination of the implants showed cell recruitment from the lumen and from the adventitial side after one month of implantation.

Although vasoconstrictive function was present in grafts, the magnitudes of response were slightly less than native tissue response. Further research is warranted in a larger, more physiologically relevant animal model before grafts are investigated in the clinic, as rats exhibit differences in comparative thrombogenicity and hemodynamics than humans. However, for an early phase study assessing graft biocompatibility and function, the results indicate that decellularized human placental arteries have considerable potential as vascular replacement materials.

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