Benavides, Omar M.Brooks, Abigail R.Cho, Sung KyungConnell, Jennifer PetscheRuano, RodrigoJacot, Jeffrey G.2015-02-272015-02-272015Benavides, Omar M., Brooks, Abigail R., Cho, Sung Kyung, et al.. "In situ vascularization of injectable fibrin/poly(ethylene glycol) hydrogels by human amniotic fluid-derived stem cells." <i>Journal of Biomedical Materials Research Part A,</i> (2015) Wiley: http://dx.doi.org/10.1002/jbm.a.35402.https://hdl.handle.net/1911/79045One of the greatest challenges in regenerative medicine is generating clinically relevant engineered tissues with functional blood vessels. Vascularization is a key hurdle faced in designing tissue constructs larger than the in vivo limit of oxygen diffusion. In this study, we utilized fibrin-based hydrogels to serve as a foundation for vascular formation, poly(ethylene glycol) (PEG) to modify fibrinogen and increase scaffold longevity, and human amniotic fluid-derived stem cells (AFSC) as a source of vascular cell types (AFSC-EC). AFSC hold great potential for use in regenerative medicine strategies, especially those involving autologous congenital applications, and we have shown previously that AFSC-seeded fibrin-PEG hydrogels have the potential to form three-dimensional vascular-like networks in vitro. We hypothesized that subcutaneously injecting these hydrogels in immunodeficient mice would both induce a fibrin-driven angiogenic host response and promote in situ AFSC-derived neovascularization. Two weeks postinjection, hydrogels were sectioned, and the following was demonstrated: the average maximum invasion distance of host murine cells into the subcutaneous fibrin/PEG scaffold was 147 ± 90 µm after 1 week and 395 ± 138 µm after 2 weeks; the average number of cell-lined lumen per square millimeter was significantly higher in hydrogels seeded with stem cells or cocultures containing stem cells (MSC, 36.5 ± 11.4; AFSC, 47.0 ± 18.9; AFSC/AFSC-EC, 32.8 ± 11.6; and MSC/HUVEC, 43.1 ± 25.1) versus endothelial cell types alone (AFSC-EC, 9.7 ± 6.1; HUVEC, 14.2 ± 8.8); and a subset of these lumen were characterized by the presence of red blood cells. Select areas of cell-seeded hydrogels contained CD31+ lumen surrounded by α-smooth muscle cell support cells, whereas control hydrogels with no cells only showed infiltration of α-smooth muscle cell–positive host cells.engThis is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by WileyJournal articleamniotic fluid-derived stem cellsvasculogenesishydrogelsfibrinangiogenesishttp://dx.doi.org/10.1002/jbm.a.35402