Study went on hold because more pre-clinical work needs to be done per FDA feedback. However, the study never went off hold and the study team has decided to close this study without opening to enrollment.

This is a single center, Phase 1/2 study in which patients with Hurler syndrome who have previously undergone allogeneic hematopoietic stem cell transplantation are treated with autologous plasmablasts engineered to express α-L-iduronidase (IDUA) using the Sleeping Beauty transposon system.

Inclusion Criteria:

• Diagnosis of Mucopolysaccharidosis type IH (MPS IH, Hurler syndrome)
• Underwent a previous hematopoietic stem cell transplant >1 year prior to study enrollment
• Age ≥3 years and ≤8 years at time of study registration
• ≥ 10 kilograms body weight
• Creatinine <1.5 normal for gender and age.
• Ejection fraction ≥ 40% by echocardiogram
• Must commit to traveling to the University of Minnesota for the necessary followup evaluations
• Must agree to stay in the Twin Cities area (<45-minute drive from the Masonic Children's Hospital) for a minimum of 5 days after each cell infusion
• Voluntary written parental consent prior to the performance of any study related procedures

Exclusion Criteria:

• Prior enzyme replacement therapy within 4 months prior to enrolling on study
• History of B cell related cancer, EBV lymphoproliferative disease or autoimmune disorders
• Evidence of active graft vs. host disease
• Requirement for systemic immune suppression
• Requirement for continuous supplemental oxygen
• Any medical condition likely to interfere with assessment of safety or efficacy of the study treatment.
• In the investigator's judgement, the subject is unlikely to complete all protocol required study visits or procedures, including follow up visits, or comply with the study requirements for participation.