Measurements from normal umbilical cord blood of four lysosomal enzymatic activities: alpha-L-iduronidase (Hurler), galactocerebrosidase (globoid cell leukodystrophy), arylsulfatase A (metachromatic leukodystrophy), arylsulfatase B (Maroteaux-Lamy)

Umbilical cord blood (UCB) has received increasing attention as a source of unrelated hematopoietic stem cells for transplantation. Lysosomal diseases have been effectively treated and normal enzymatic activity has occurred s ubsequent to engraftment using UCB, The use of donor cells with normal amou nts of enzyme, rather than those from carriers whose level may be 50% or le ss, is an obvious goal, The frequency of such heterozygotes varies from 1:1 0 to 1:140 or lower depending upon the disease at issue. We assayed the lev els of lysosomal enzymes in normal UCB in random samples as well as those u sed for transplantation. We measured the following enzymatic activities: al pha-L-iduronidase (Hurler), galactocerebrosidase (globoid cell leukodystrop hy) and arylsulfatase A (metachromatic leukodystrophy), For the latter, lev els of activity in UCB are comparable to those found in adult blood, In the case of arylsulfatase B (Maroteaux-Lamy) a level lower than adult level wa s found. An informed choice by the transplanting physician based on the act ivity of the relevant enzyme in the UCB donor will provide a better opportu nity for an improved prognosis for more complete correction of the recipien t's primary disease.