Abstract
Mucopolysaccharidosis II (MPS II—
Hunter syndrome) is an X-linked lysosomal storage disorder caused by a
deficiency in
iduronate-2
sulfatase.
Enzyme replacement therapy does not cross the
blood-brain barrier (BBB), limiting the results in neurological forms of the
disease. Another
treatment option for MPS,
hematopoietic stem cell transplantation (HSCT) has become the
treatment of choice for the severe form of MPS I since it can preserve neurocognition when performed early in the
course of the
disease. Even though the intravenous
therapy does not cross the BBB, it has become the recommended
treatment for MPS II, and HSCT was not often indicated. In an attempt to understand why this
treatment modality is rejected by most
specialists as a
treatment option for
patients with
Hunter syndrome, we sought to raise all HSCT cases already reported in the scientific
literature. Databases used were
Medline/
PubMed,
Lilacs/BVS Cochrane
Library, DARE, SciELO, and SCOPUS. Different combinations of the terms "
mucopolysaccharidosis II," "
Hunter syndrome," "
hematopoietic stem cell transplantation," "
bone marrow transplantation," and "
umbilical cord blood stem cell transplantation" were used. A total of 780 articles were found. After excluding redundant references and articles not related to the theme, 26 articles were included. A descriptive summary of each article is presented, and the main features are summed up. The clinical experience with HSCT in MPS II is small, and most of the available
literature is outdated. The available data reveal poor
patient selection criteria, varied conditioning regimens, distinct follow-up
parameters, and post-HSCT outcomes of interest, making impossible to compare and generalize the results obtained. Recently, after the development of new conditioning
protocols and
techniques and the creation of
bone marrow donor registries and
umbilical cord banks, HSCT has become more secure and accessible. It seems now appropriate to reconsider HSCT as a
treatment option for the neuronopathic form of MPS II.