Tetrahydrobiopterin, nitric oxide synthases and transplant vasculopathy : investigations on a murine model of heterotopic cervical aortic allograft transplantation

Hochschulschrift

Zusammenfassung: Transplant Vasculopathy (TV) is currently a chief challenge in solid organ transplantation, prob- ably second only to organ shortage. Long-term graft and patient survival crucially depend on its occurrence. This alloimmune-mediated graft vascular stenosis (neointima formation) seems to be closely associated with Ischemia Reperfusion Injury (IRI), an early oxidative damage fol- lowing graft reperfusion. Recently, the supplementation of exogenous 6R-L-Erythro-5,6,7,8- TetraHydroBiopterin (BH4) – an essential cofactor for the Nitric Oxide Synthase (NOS) and cru- cial for the production of the potent vasodilator Nitric Oxide (NO) – has been shown to abrogate this early graft damage. The postulated mechanism is the prevention of an uncoupling of the func- tional NOS dimer and subsequent formation of tissue-damaging Reactive Oxygen Species (ROS) by exogenous supply of the essential cofactor BH4. Considering the association between IRI and TV, aim of this study was to analyze whether exogenous application of BH4 would also prevent the development of TV.Using a well established cervical transplantation model of murine aortic allografts,two groups were compared: an untreated Control Group (CG) and a BH4-supplemented Experimental Group (EG). BH4 was administered to the donor animal 2 minutes before starting organ recovery. Tissue samples were harvested and further analyzed either directly following graft recovery, or following 24 hours of Cold Ischemia Time (CIT), or following 2 hours or 28 days of reperfusion. Analy- ses comprised histomorphological assessment and immunohistochemical staining to evaluate the severity of inflammation, endothelial injury in the graft’s vasculature and neointima formation, measurement of intragraft BH4 levels by High Performance Liquid Chromatography (HPLC) to control for successful cofactor administration and determination of NOS’ dimer-monomer ratio as an indicator for NOS uncoupling.It was found that the administration of exogenous BH4 significantly increased intragraft BH4 al- ready at the time of organ recovery. Also, TV did not occur in the cofactor-treated group during the observed period of time, whereas a significantly increased ratio of endothelial intima-media- thickness could be detected in the untreated group after 4 weeks of reperfusion. Even though eNOS dimer-monomer-ratio was found to be increased in the EG at the point of time where intragraft BH4 was significantly higher, the difference did not reach statistical significance. In contrast, only at the latest time point, when the maximal extent of TV was observed in the CG, the EG – with its significantly reduced TV – showed a significantly elevated ratio. There were no differences regarding inflammatory infiltrates and endothelial injury in histopathological and immunohisto- chemical staining.In this model, exogenous administration of BH4 was observed to prevent the development of se- vere TV. Rather than on the modulation of infiltrating inflammatory cells, the protective effect of BH4 seems to rely on the prevention of endothelial dysfunction in the transplanted graft

Angaben zum Objekt

• Standort: Deutsche Nationalbibliothek Frankfurt am Main
• Umfang: Online-Ressource
• Sprache: Englisch
• Anmerkungen: Albert-Ludwigs-Universität Freiburg, Dissertation, 2016

Beteiligte, Orts- und Zeitangaben

• Ereignis: Veröffentlichung
• (wo): Freiburg
• (wer): Universität
• (wann): 2016
• Urheber: Wiesner, Christina Josefine
• Beteiligte Personen und Organisationen: Hopt, Ulrich T. ; Daniel-Swarovski-Labor

Weitere Informationen

• DOI: 10.6094/UNIFR/10552
• URN: urn:nbn:de:bsz:25-freidok-105524
• Rechteinformation: Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Letzte Aktualisierung: 14.08.2025, 10:44 MESZ