Lentiviral-transduced human mesenchymal stem cells persistently express therapeutic levels of enzyme in a xenotransplantation model of human disease

¹ Washington University School of Medicine, Departments of Internal Medicine, St. Louis, Missouri 63110, USA
² Washington University School of Medicine, Departments of Otolaryngology, St. Louis, Missouri 63110, USA
³ Washington University School of Medicine, Departments of St. Louis University School of Medicine, Department of Pathology, St. Louis, MO 63104, USA
⁴ Washington University School of Medicine, Departments of University of California at Davis, Stem Cell Program, Sacramento, CA 95817, USA.
⁵ Washington University School of Medicine, Departments of Internal Medicine, St. Louis, Missouri 63110, USA; University of California at Davis, Stem Cell Program, Sacramento, CA 95817, USA.
⁶ Washington University School of Medicine, Departments of Internal Medicine, and Genetics, St. Louis, Missouri 63110, USA

^* To whom correspondence should be addressed. E-mail: msands{at}im.wustl.edu.

	Abstract

Bone marrow-derived mesenchymal stem cells (MSC) are a promising platform for cell- and gene-based treatment of inherited and acquired disorders. We recently showed that human MSC distribute widely in a murine xenotransplantation model. In the current study we have determined the distribution, persistence and ability of lentivirally-transduced human MSC to express therapeutic levels of enzyme in a xenotransplantation model of human disease (NOD-SCID-MPSVII). Primary human bone marrow-derived MSC were transduced ex vivo with a lentiviral vector expressing either eGFP (MSC-eGFP) or the lysosomal enzyme -glucuronidase (MSC-GUSB). Lentiviral transduction did not affect any in vitro parameters of MSC function or potency. One million cells from each population were transplanted intraperitoneally into separate groups of neonatal NOD-SCID MPSVII mice. Transduced MSC persisted in the transplanted animals and comparable numbers of donor MSC were detected at 2 and 4 months post transplant in multiple organs. MSC-GUSB expressed therapeutic levels of protein in the recipients, raising circulating serum levels of GUSB to nearly 40% of normal. This level of circulating enzyme was sufficient to normalize the secondary elevation of other lysosomal enzymes and reduce lysosomal distention in several tissues. In addition, at least one physiologic marker of disease, retinal function, was normalized following transplantation of MSC-GUSB. These data provide evidence that transduced human MSC retain their normal trafficking ability in vivo and persist for at least 4 months, delivering therapeutic levels of protein in an authentic xenotransplantation model of human disease.