High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy for the Metabolic Assessment of Acute Rejection After Cardiac Transplantation in Rats.

PURPOSE: To evaluate the potential of high-resolution magic angle spinning (HR-MAS) 1 H nuclear magnetic resonance (NMR) spectroscopy for metabolite characterization and the differentiation of acute rejection after heart transplantation in rat models.

METHODS: We transplanted syngeneic heart grafts from Lewis rats (n = 4) and allogeneic heart grafts from F344 rats (n = 4) heterotopically into Lewis recipients. On day 7 postoperatively, the transplanted hearts were harvested for ex vivo 1 H NMR spectroscopy and HR-MAS 1 H NMR spectroscopy. 1 H NMR spectroscopy and HR-MAS 1 H NMR spectroscopy were performed at 4.7 T and 11.7 T, respectively. Metabolomic profiles contributing to the differentiation of allogeneic and syngeneic graft groups were statistically assessed by orthogonal partial least squares discriminant analysis (OPLS/O2PLS-DA). Metabolite concentrations were normalized by total spectral intensities and were compared using Mann-Whitney U tests.

RESULTS: One allogeneic graft that showed extensive necrotic change suggesting graft failure was excluded from the statistical analysis of the NMR spectroscopy. In the 4.7-T 1 H NMR spectroscopy, the creatine peak was decreased in the allogeneic group. The PLS-DA and OPLS/O2PLS-DA score plot demonstrated good discrimination of the allogeneic graft group from syngeneic graft group. The concentrations of creatine, myo-inositol, glucose, niacinamide, hypoxanthine, inosine, and glutamine were significantly decreased in the allogeneic graft group, whereas the concentrations of glycine, phosphoethanolamine, xanthine, sn-glycero-3-phosphocholine, leucine, valine, and tyrosine were significantly increased (P < .05).

CONCLUSIONS: HR-MAS 1 H NMR spectroscopy can metabolically characterize the acute rejection of heart transplantation.