Hepatocyte Transplantation Improves Phenotype and Extends Survival in a Murine Model of Intermediate Maple Syrup Urine Disease

Abstract

Maple syrup urine disease (MSUD; OMIM 248600) is an inborn error of metabolism of the branched chain alpha-ketoacid dehydrogenase (BCKDH) complex that is treated primarily by dietary manipulation of branched-chain amino acids (BCAA). Dietary restriction is lifelong and compliance is difficult. Liver transplantation significantly improves outcomes; however, alternative therapies are needed. To test novel therapies such as hepatocyte transplantation (HTx), we previously created a murine model of intermediate MSUD (iMSUD), which closely mimics human iMSUD. LacZ-positive murine donor hepatocytes were harvested and directly injected (10(5) cells/50 microl) into liver of iMSUD mice (two injections at 1-10 days of age). Donor hepatocytes engrafted into iMSUD recipient liver, increased liver BCKDH activity, improved blood total BCAA/alanine ratio, increased body weight at weaning, and extended the lifespan of HTx-treated iMSUD mice compared to phosphate-buffered saline (PBS)-treated and untreated iMSUD mice. Based on these data demonstrating partial metabolic correction of iMSUD in a murine model, coupled to the fact that multiple transplants are possible to enhance these results, we suggest that HTx represents a promising therapeutic intervention for MSUD that warrants further investigation.

Dynamic Arginine Methylation of Tumor Necrosis Factor (TNF) Receptor-associated Factor 6 Regulates Toll-like Receptor Signaling

“…Isolation of Mouse Primary Hepatocytes-Primary mouse hepatocytes were isolated from 5-week-old male C57/B6 mice by a two-step collagenase perfusion method as described previously (12). All perfusion solutions were maintained at 37°C using a heated water bath, and the perfusion was carried out using a peristaltic pump.…”

Cell Transplantation: A Possible Alternative to Orthotopic Liver Transplant (OLT)

“…iMSUD mice were given multiple infusions of undifferentiated AE cells, either freshly isolated or cryopreserved, directly into the liver parenchyma. AE cell transplantation partially corrected iMSUD mice similarly to the partial correction previously obtained with hepatocyte transplantation (Skvorak et al, 2009a;. While untreated iMSUD mice grew sickly and all died prior to 27 days of age, iMSUD-treated mice displayed improved BCKDH enzyme activity, reduced BCAA and other relevant metabolites in the brain and blood, their body weight mimicked that of healthy wildtype littermates, and >70% of animals survived to day of life 100 (Skvorak et al, 2010).…”

“…Importantly, Harding's group showed the correction of murine phenylketonuria (PKU) despite low engraftment of cells (Hamman et al, 2005); Harding & Gibson (2010) later suggest only 10-20% repopulation may be sufficient to correct PKU clinically. Our group also recently reported a significant partial correction of murine intermediate MSUD despite very low (~3%) repopulation of the liver (Skvorak et al, 2009a;. As a result, HTx has gained attention as a potential therapeutic intervention for a number of liver diseases, and transplantation of hepatocytes corresponding to 1-5% of total liver mass (1.5-9.0 billion hepatocytes) can be expected to have a positive impact.…”

Translation of Amnion Stem Cells to the Clinic

“…Preclinical studies of hAEC therapy of metabolic liver disease [35,36], so additional studies were initiated to determine if hAEC transplantation was effective therapy for this liver disease.…”