Internalized antigens must be removed to prepare hypoimmunogenic mesenchymal stem cells for cell and gene therapy.
Adult stem cells from human bone marrow stroma, referred to as mesenchymal stem cells or marrow stromal cells (hMSCs), are attractive candidates for clinical use. The optimal conditions for hMSC expansion require medium supplemented with fetal calf serum (FCS). Some forms of cell therapy will involve multiple doses, raising a concern over immunological reactions caused by medium-derived FCS proteins. By a sensitive fluorescence-based assay we determined that 7 to 30 mg of FCS proteins are associated with a standard preparation of 100 million hMSCs, a dosage that probably will be needed for clinical therapies. Here we present ex vivo growth conditions for hMSCs that reduce the FCS proteins to less than 100 ng per 100 million hMSCs, approximately a 100,000-fold reduction. The cells maintain their proliferative capacity and sustain their ability for multilineage differentiation. Experiments in rats demonstrate that rat MSCs grown in 20% FCS induce a substantial humoral response after repeated administrations, whereas cells grown under the conditions described in this study reduce the immunogenicity in terms of IgG response over 1000-fold to barely detectable levels. Our results have the potential to dramatically improve cellular and genetic therapies using hMSCs and perhaps other cells.
Spees
Jeffrey L
JL
Center for Gene Therapy, Tulane University Health Sciences Center, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
Gregory
Carl A
CA
Singh
Harpreet
H
Tucker
H Alan
HA
Peister
Alexandra
A
Lynch
Patrick J
PJ
Hsu
Shu-Ching
SC
Smith
Jason
J
Prockop
Darwin J
DJ
D000255:Adenosine Triphosphate / Q000032:analysis; D000818:Animals; D000954:Antigens, Surface / Q000276:immunology; D001798:Blood Proteins / Q000276:immunology* / Q000378:metabolism; D002417:Cattle; D002454:Cell Differentiation; D003470:Culture Media; D005312:Fetal Blood / Q000276:immunology; D016650:Fluorescein-5-isothiocyanate; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods*; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D051381:Rats
D000954:Antigens, Surface; D001798:Blood Proteins; D003470:Culture Media; D007074:Immunoglobulin G; D000255:Adenosine Triphosphate; D016650:Fluorescein-5-isothiocyanate