In vivo 1H MRS and 31P MRSI of the response to cyclocreatine in transgenic mouse liver expressing creatine kinase

Min Hui Cui, Kamaiah Jayalakshmi, Laibin Liu, Chandan Guha, Craig A. Branch

Research output: Contribution to journalArticle

Abstract

Hepatocyte transplantation has been explored as a therapeutic alternative to liver transplantation, but a means to monitor the success of the procedure is lacking. Published findings support the use of in vivo 31P MRSI of creatine kinase (CK)-expressing hepatocytes to monitor proliferation of implanted hepatocytes. Phosphocreatine tissue level depends upon creatine (Cr) input to the CK enzyme reaction, but Cr measurement by 1H MRS suffers from low signal-to-noise ratio (SNR). We examine the possibility of using the Cr analog cyclocreatine (CCr, a substrate for CK), which is quickly phosphorylated to phosphocyclocreatine (PCCr), as a higher SNR alternative to Cr. 1H MRS and 31P MRSI were employed to measure the effect of incremental supplementation of CCr upon PCCr, γ-ATP, pH and Pi/ATP in the liver of transgenic mice expressing the BB isoform of CK (CKBB) in hepatocytes. Water supplementation with 0.1% CCr led to a peak total PCCr level of 17.15±1.07mmol/kg wet weight by 6weeks, while adding 1.0% CCr led to a stable PCCr liver level of 18.12±3.91mmol/kg by the fourth day of feeding. PCCr was positively correlated with CCr, and ATP concentration and pH declined with increasing PCCr. Feeding with 1% CCr in water induced an apparent saturated level of PCCr, suggesting that CCr quantization may not be necessary for quantifying expression of CK in mice. These findings support the possibility of using 31P MRS to noninvasively monitor hepatocyte transplant success with CK-expressing hepatocytes.

Original languageEnglish (US)
Pages (from-to)1634-1644
Number of pages11
JournalNMR in Biomedicine
Volume28
Issue number12
DOIs
StatePublished - Dec 1 2015

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Keywords

  • Creatine kinase
  • Cyclocreatine
  • Hepatocytes
  • MRS
  • Mouse liver
  • Phosphocyclocreatine
  • Spectroscopic imaging

ASJC Scopus subject areas

  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging
  • Spectroscopy

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