Human mesenchymal stromal cells undergo apoptosis and fragmentation after intravenous application in immune-competent mice.
The biodistribution of human MSCs after systemic delivery is incompletely understood. We investigated the changes in cell size and cell surface markers of human MSCs after intravenous (IV) injection in immune competent mice.



Male human MSCs were labeled with fluorescent vital dye PKH67 and tracked after IV administration in C57/BL6 mice. MSCs were tracked in blood and different murine tissues by human SRY gene quantitative polymerase chain reaction (qPCR) analysis, flow cytometry and fluorescence microscopy. Calibrated microbeads were used to track the size of transplanted MSCs.



The majority of injected MSCs were detected by qPCR in the lungs 5 min after transplantation, whereas <0.1% were detected in other tissues over 24 h. Flow cytometric and fluorescence microscopic analysis indicated that MSCs continuously decreased in size after transplantation and underwent fragmentation. The majority of PKH+MSCs and their fragments were found in lungs and liver. PKH+MSCs rapidly became positive for annexin V, propidium iodide and calreticulin, indicating loss of cell integrity. In addition, PKH+fragments co-stained with antibodies against C3b, F4/80 and/or GR-1 indicating opsonization. Preincubation of MSCs in hyperosmolaric hydroxyethyl starch (HyperHAES) decreased MSCs size before transplantation, delayed the loss of viability markers and increased the frequency of traceable MSCs up to 24 h after transplantation.



PKH67 labeled MSCs are fragmented after IV injection in mice, acquire apoptotic and phagocytic cell markers and accumulate in the lungs and liver.
Institute of Transfusion Medicine and Immune Hematology, German Red Cross Blood Donor Service, University of Frankfurt, UK. Electronic address: Johannes_leibacher@web.de.
Johannes
J
Leibacher
Institute of Transfusion Medicine and Immune Hematology, German Red Cross Blood Donor Service, University of Frankfurt, UK.
Katrin
K
Dauber
Institute of Transfusion Medicine and Immune Hematology, German Red Cross Blood Donor Service, University of Frankfurt, UK.
Sabrina
S
Ehser
Institute of Transfusion Medicine and Immune Hematology, German Red Cross Blood Donor Service, University of Frankfurt, UK.
Veronika
V
Brixner
Institute of Transfusion Medicine and Immune Hematology, German Red Cross Blood Donor Service, University of Frankfurt, UK.
Katarina
K
Kollar
Institute of Transfusion Medicine and Immune Hematology, German Red Cross Blood Donor Service, University of Frankfurt, UK.
Anja
A
Vogel
Institute of Transfusion Medicine and Immune Hematology, German Red Cross Blood Donor Service, University of Frankfurt, UK.
Gabi
G
Spohn
Institute of Transfusion Medicine and Immune Hematology, German Red Cross Blood Donor Service, University of Frankfurt, UK.
Richard
R
Schäfer
Institute of Transfusion Medicine and Immune Hematology, German Red Cross Blood Donor Service, University of Frankfurt, UK.
Erhard
E
Seifried
Institute of Transfusion Medicine and Immune Hematology, German Red Cross Blood Donor Service, University of Frankfurt, UK; Blood Transfusion Services Zurich and Grisons, Swiss Red Cross, Switzerland.
Reinhard
R
Henschler
D000818:Animals; D017209:Apoptosis; D015415:Biomarkers / Q000032:analysis; D048429:Cell Size; D002470:Cell Survival; D005434:Flow Cytometry / Q000379:methods; D064593:Heterografts; D006801:Humans; D007275:Injections, Intravenous; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods*; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D008810:Mice, Inbred C57BL; D009930:Organic Chemicals / Q000493:pharmacokinetics; D014018:Tissue Distribution
D015415:Biomarkers; D009930:Organic Chemicals; C451241:PKH67
PKH67; biodistribution; hyperosmolaric media; intravenous application; mesenchymal stromal cells; mouse