Ultrastructural findings of cutaneous nerves in patients with Hunter's syndrome following hematopoietic stem cell transplant.

Hematopoietic stem cell transplant (HSCT) has been performed on patients with Hunter's syndrome. If applied, evaluation of recovery in various organs is needed for long-term follow-up. However, it remains unclear whether HSCT is effective against the neurological involvement in Hunter's syndrome, and morphological evaluation of recovery is inconsistent. We observed the degree of cutaneous nerve involvement in patients with Hunter's syndrome ultrastructurally before and after HSCT. Electron microscopic studies revealed that membrane-bound clear vacuoles were still observed in the cytoplasm of endoneurial fibroblasts and Schwann cells 2 months and 2 years, respectively, after HSCT. On the other hand, only a few vacuoles were present in dermal fibroblasts at 2 months after HSCT, and these disappeared within 2 years. These results suggest that the persistence of clear vacuoles in endoneurial fibroblasts and Schwann cells indicates a disturbed internal condition in the endoneurium 2 years after HSCT. Skin biopsies can be used in patients with Hunter's syndrome to study peripheral nerves for long-term follow-up to evaluate morphological efficacy.