Analysis of Tissues Following Mesenchymal Stromal Cell Therapy in Humans Indicates Limited Long-Term Engraftment and No Ectopic Tissue Formation

Division of Clinical Immunology and Transfusion Medicine, Department of Laboratory Medicine
Stem Cells (Impact Factor: 7.7). 07/2012; 30(7):1575-8. DOI: 10.1002/stem.1118
Source: PubMed

ABSTRACT Mesenchymal stromal cells (MSCs) are explored as a novel treatment for a variety of medical conditions. Their fate after infusion is unclear, and long-term safety regarding malignant transformation and ectopic tissue formation has not been addressed in patients. We examined autopsy material from 18 patients who had received human leukocyte antigen (HLA)-mismatched MSCs, and 108 tissue samples from 15 patients were examined by PCR. No signs of ectopic tissue formation or malignant tumors of MSC-donor origin were found on macroscopic or histological examination. MSC donor DNA was detected in one or several tissues including lungs, lymph nodes, and intestine in eight patients at levels from 1/100 to <1/1,000. Detection of MSC donor DNA was negatively correlated with time from infusion to sample collection, as DNA was detected from nine of 13 MSC infusions given within 50 days before sampling but from only two of eight infusions given earlier. There was no correlation between MSC engraftment and treatment response. We conclude that MSCs appear to mediate their function through a "hit and run" mechanism. The lack of sustained engraftment limits the long-term risks of MSC therapy.

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Available from: Guido Moll, Aug 17, 2015
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    • "Although genetic instability of flask-and Quantum bioreactor-expanded MSCs and transformation of or teratoma formation by human MSCs have not been observed so far [16] [18] [49] [50] [51], the development of MSC-derived malignancies or ectopic tissue is a rational concern regarding their transplantation into humans. "
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    • "Although genetic instability of flask-and Quantum bioreactor-expanded MSCs and transformation of or teratoma formation by human MSCs have not been observed so far [16] [18] [49] [50] [51], the development of MSC-derived malignancies or ectopic tissue is a rational concern regarding their transplantation into humans. "
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    ABSTRACT: The discovery of regenerative and immunosuppressive capacities of mesenchymal stromal cells (MSCs) raises hope for patients with tissue-damaging or severe, treatment-refractory autoimmune disorders. We previously presented a method to expand human MSCs in a bioreactor under standardized Good Manufacturing Practice conditions. Now we characterized the impact of critical treatment conditions on MSCs with respect to immunosuppressive capabilities and proliferation.MethodsMSC proliferation and survival after γ irradiation were determined by 5-carboxyfluorescein diacetate N-succinimidyl ester and annexinV/4′,6-diamidino-2-phenylindole (DAPI) staining, respectively. T-cell proliferation assays were used to assess the effect of γ irradiation, passaging, cryopreservation, post-thaw equilibration time and hypoxia on T-cell suppressive capacities of MSCs. Quantitative polymerase chain reaction and β-galactosidase staining served as tools to investigate differences between immunosuppressive and non-immunosuppressive MSCs.Resultsγ irradiation of MSCs abrogated their proliferation while vitality and T-cell inhibitory capacity were preserved. Passaging and long cryopreservation time decreased the T-cell suppressive function of MSCs, and postthaw equilibration time of 5 days restored this capability. Hypoxic culture markedly increased MSC proliferation without affecting their T-cell-suppressive capacity and phenotype. Furthermore, T-cell suppressive MSCs showed higher CXCL12 expression and less β-galactosidase staining than non-suppressive MSCs.DiscussionWe demonstrate that γ irradiation is an effective strategy to abrogate MSC proliferation without impairing the cells' immunosuppressive function. Hypoxia significantly enhanced MSC expansion, allowing for transplantation of MSCs with low passage number. In summary, our optimized MSC expansion protocol successfully addressed the issues of safety and preservation of immunosuppressive MSC function after ex vivo expansion for therapeutic purposes.
    Cytotherapy 11/2014; 17(2). DOI:10.1016/j.jcyt.2014.10.004 · 3.10 Impact Factor
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    • "Among the fifteen patients available for PCR analysis, long-term engraftment of MSCs appeared to be low due to rejection by the recipient immune system or an inability of MSCs to survive and engraft after intravenous infusion. MSC injections did not induce side effects [15]. Finally, in spite of successful clinical trials using MSCs, there is few data concerning the long-term engraftment and side effects after MSC systemic injections; transplanted stem cells must not form teratomas or undergo transformation and they must not promote tumour recurrence. "
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    ABSTRACT: There is little information on the fate of infused mesenchymal stem cells (MSCs) and long-term side effects after irradiation exposure. We addressed these questions using human MSCs (hMSCs) intravenously infused to nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice submitted to total body irradiation (TBI) or local irradiation (abdominal or leg irradiation). The animals were sacrificed 3 to 120 days after irradiation and the quantitative and spatial distribution of hMSCs were studied by polymerase chain reaction (PCR). Following their infusion into nonirradiated animals, hMSCs homed to various tissues. Engraftment depended on the dose of irradiation and the area exposed. Total body irradiation induced an increased hMSC engraftment level compared to nonirradiated mice, while local irradiations increased hMSC engraftment locally in the area of irradiation. Long-term engraftment of systemically administered hMSCs in NOD/SCID mice increased significantly in response to tissue injuries produced by local or total body irradiation until 2 weeks then slowly decreased depending on organs and the configuration of irradiation. In all cases, no tissue abnormality or abnormal hMSCs proliferation was observed at 120 days after irradiation. This work supports the safe and efficient use of MSCs by injection as an alternative approach in the short- and long-term treatment of severe complications after radiotherapy for patients refractory to conventional treatments.
    Stem cell International 02/2014; 2014:939275. DOI:10.1155/2014/939275 · 2.81 Impact Factor
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