title: Uptake of a recombinant human alpha-L-iduronidase (laronidase) by cultured fibroblasts and osteoblasts.
abstract: To examine the uptake of a recombinant human alpha-L-iduronidase (laronidase) by cultured fibroblasts from a patient with mucopolysaccharidosis I (MPS I) and its effect on the cleavage of accumulated substrates, we performed enzymological, Western blotting, immunocytochemical and morphological studies. Laronidase was incorporated into the MPS I cells dose-dependently mainly via mannose 6-phosphate (M6P) receptors. Then the incorporated enzyme was transported to lysosomes and processed to the mature form, the pathological changes of the cells being improved. Furthermore, we compared the uptake of laronidase by cultured mouse osteoblasts with that by cultured mouse fibroblasts. The enzyme was incorporated into the cultured mouse osteoblasts mainly via M6P receptors, although mannose (Man) receptors were partially involved in the uptake of the enzyme, as in the cultured fibroblasts. But the uptake by the former was apparently lower than that by the latter. The administration of a high dose of the enzyme or development of a recombinant alpha-L-iduronidase containing many M6P residues is required for further improvement of enzyme replacement therapy for skeletal disorders caused by MPS I.
authors.affiliation: Department of Clinical Genetics, The Tokyo Metropolitan Institute of Medical Science, Tokyo Metropolitan Organization for Medical Research, Bunkyo-ku, Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsukimura
authors.forename: Youichi
authors.initials: Y
authors.lastname: Tajima
authors.forename: Ikuo
authors.initials: I
authors.lastname: Kawashima
authors.forename: Tomoko
authors.initials: T
authors.lastname: Fukushige
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Kanzaki
authors.forename: Takuro
authors.initials: T
authors.lastname: Kanekura
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ikekita
authors.forename: Kanako
authors.initials: K
authors.lastname: Sugawara
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Tadayasu
authors.initials: T
authors.lastname: Togawa
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sakuraba