Limited autologous vascular graft availability and poor patency rates of synthetic grafts for small-diameter revascularization (e.g., coronary artery bypass, peripheral bypass, arteriovenous graft for hemodyalisis access, etc.) remain a concern in the surgical community. A tissue engineering vascular graft (TEVG), including suitable cell source, scaffold, seeding, and culture methods can potentially solve these limitations. Muscle-derived stem cells (MDSCs) are multipotent cells, with long-term proliferation and self-renewal capabilities, which represent a valid candidate for vascular tissue engineering applications due to their plasticity/heterogeneity. The poly(ester urethane) urea (PEUU) is also an attractive potential candidate for use as a TEVG due to its elasticity and tunable mechanical and degradation properties. We hypothesized that a novel scaffold optimally seeded with stem cells, acutely cultured and stimulated in vitro, and ultimately implanted in vivo will remodel into a functional vascular tissue.
To test this hypothesis, we developed an innovative, multidisciplinary framework to fabricate and culture a TEVG in a timeframe compatible with clinical practice. In this approach, MDSCs were incorporated into a newly-designed and characterized PEUU-based scaffold via a novel seeding device, which was tested quantitatively for cell seeding uniformity and viability. The seeded TEVGs were acutely cultured in dynamic conditions and assessed for cell phenotype, proliferation, and spreading. The conduits were then implanted systemically in a small and a large animal model and assessed, at different time points, for patency rate, remodeling, and cellular engraftment and phenotype.
The seeding technology demonstrated a rapid, efficient, reproducible, and quantitatively uniform seeding without affecting cell viability. The PEUU scaffold that was developed is suitable for arterial applications, exhibiting appropriate strength, compliance, and suture retention properties. The dynamic culture resulted in cell proliferation and spreading within the 3D scaffold environment. Rat preclinical studies suggested a role of the seeded MDSCs in the maintenance of patency and in the remodeling of the TEVG toward a native-like structure. Pig studies were inconclusive due to a poor pre-implantation cell density.
Future work should address this and other issues encountered during the large animal study, and should test longer time points in both models. Finally, this approach might benefit from a more readily available cell source such as the bone marrow.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-11262008-133840 |
| Date | 28 January 2009 |
| Creators | Soletti, Lorenzo |
| Contributors | William R. Wagner, David A. Vorp, Johnny Huard, Bradley Keller |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-11262008-133840/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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