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Can Placental Stem Cells Provide Relief from Lysosomal Storage Disorder?

Review of “Liver-Directed Human Amniotic Epithelial Cell Transplantation Improves Systemic Disease Phenotype in Hurler Syndrome Mouse Model” from STEM CELLS Translational Medicine by Stuart P. Atkinson

A deficiency in the glycosaminoglycan (GAG)-degrading enzyme α-l-iduronidase (IDUA) leads to the inherited lysosomal storage disorder Mucopolysaccharidosis type 1 (MPS1) or Hurlers syndrome [1]. While current therapies improve life expectancy, the skeletal and neurological phenotypes affecting patients' quality of life remain a significant problem.

Now, researchers from the laboratory of Toshio Miki (University of Southern California, USA) report on a safe and efficient new treatment strategy for MPS1; enzyme replacement via the engraftment of a placental stem cell (human amnion epithelial cells [hAECs]) into the liver [2-4]. Can this strategy described in STEM CELLS Translational Medicine study [5] soon provide relief for human patients suffering from this devastating lysosomal storage disorder?

After confirming the presence of abundant IDUA-containing lysosomes, the authors of the study transplanted hAECs into the liver of immunodeficient IDUA-knockout newborn mice. Much like mesenchymal stem cells (MSCs), hAECs display many advantageous characteristics, including low immunogenicity, immunomodulatory/anti-inflammatory activity, and multilineage differentiation potential. Analyses indicated that the transplantation of around 2 million hAECs restored long-term IDUA function in the liver (>20 weeks) and led to the hoped-for increase in systemic GAG degradation without tumor formation. Encouragingly, these metabolic improvements also correlated with improvements in the morphology, volume, and density of cranial and facial bones and enhancements to sensorimotor coordination when compared to control untreated mice (See Figure).

Success! The authors note that as little as 0.13% of normal IDUA activity can reverse disease phenotype [6] and so, even limited survival and engraftment of hAECs in vivo may function as a potent treatment option to improve skeletal and neurological phenotypes of MPS1 patients. Furthermore, the safety and readily available nature of hAECs also promote their application as a novel therapy for MPS1, and perhaps other, congenital metabolic lysosomal storage disorders.

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  1. Bie H, Yin J, He X, et al. Insights into mucopolysaccharidosis I from the structure and action of alpha-L-iduronidase. Nat Chem Biol 2013;9:739-745.
  2. Marongiu F, Gramignoli R, Dorko K, et al. Hepatic differentiation of amniotic epithelial cells. Hepatology 2011;53:1719-1729.
  3. Hong SB, Seo MS, Park SB, et al. Therapeutic effects of human amniotic epithelial stem cells in Niemann-Pick type C1 mice. Cytotherapy 2012;14:630-638.
  4. Sakuragawa N, Enosawa S, Ishii T, et al. Human amniotic epithelial cells are promising transgene carriers for allogeneic cell transplantation into liver. Journal of human genetics 2000;45:171-176.
  5. Rodriguez NS, Yanuaria L, Parducho KMR, et al. Liver-Directed Human Amniotic Epithelial Cell Transplantation Improves Systemic Disease Phenotype in Hurler Syndrome Mouse Model. STEM CELLS Translational Medicine 2017;6:1583-1594.
  6. Ashton LJ, Brooks DA, McCourt PA, et al. Immunoquantification and enzyme kinetics of alpha-L-iduronidase in cultured fibroblasts from normal controls and mucopolysaccharidosis type I patients. Am J Hum Genet 1992;50:787-794.