Internalized Antigens Must Be Removed to Prepare Hypoimmunogenic Mesenchymal Stem Cells for Cell and Gene Therapy

Abstract

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.

The Effect of In Vivo Mobilization of Bone Marrow Stem Cells on the Pancreas of Diabetic Albino Rats (A Histological & Immunohistochemical Study)

“…infusion (33). In addition, culture of human MSCs is usually performed in media containing fetal calf serum (FCS) where the cells can internalize (39) and can produce immune reactions with repeated administrations of the cells (40). The above mentioned data concerning the risk of administration of Autologous human MSCs support our trend in using StemEnhance as a simple procedure for the replacement of injured β cells in diabetic animals.…”

Inactivated human platelet lysate with psoralen: a new perspective for mesenchymal stromal cell production in Good Manufacturing Practice conditions

“…Although human MSCs themselves are not highly immunogenic, when expanded in xenogeneic sera such as in fetal bovine serum (FBS), they are likely to generate immune responses in some patients after administration (10,11). It was shown that a single preparation of 10 8 hMSCs grown under standard conditions in FBS carry with it approximately 7-30 mg of FBS proteins (10).…”

“…Although human MSCs themselves are not highly immunogenic, when expanded in xenogeneic sera such as in fetal bovine serum (FBS), they are likely to generate immune responses in some patients after administration (10,11). It was shown that a single preparation of 10 8 hMSCs grown under standard conditions in FBS carry with it approximately 7-30 mg of FBS proteins (10). Thus, in view of a clinical GMP production, the use of xenogenic serum is complicated as there is high lot-to-lot variability and it is associated with a risk of transmitting infectious agents and immunizing effects (12,13).…”

State of the art and future perspectives of articular cartilage regeneration: a focus on adipose-derived stem cells and platelet-derived products

“…Besides the fact that the production of FCS is accompanied by ethical concerns, it is reported that MSC cultured in the presence of FCS internalize xenogeneic proteins (Spees et al, 2004). This implies the risk of virus and prion transmission and the use of FCS for human products is therefore not recommended by European legislation (Doucet et al, 2005).…”