Long-Term Quantitative Biodistribution and Side Effects of Human Mesenchymal Stem Cells (hMSCs) Engraftment in NOD/SCID Mice following Irradiation

Table 2

hMSC biodistribution in function of the irradiation dose 6 weeks after local irradiation of the right posterior leg at 15 to 25 Gy.

Organs (positive per mice)	Dose of irradiation
	15 Gy	20 Gy	25 Gy
Brain	0/8 (0%)	4/10 (40%)	8/8 (100%)
Heart	6/8 (75%)	0/6 (0%)	8/8 (100%)
Lung	2/6 (33%)	4/10 (40%)	8/8 (100%)
Liver	0/8 (0%)	6/8 (75%)	8/8 (100%)
Spleen	0/8 (0%)	5/10 (50%)	8/8 (100%)
Abdominal area
Kidney	2/6 (33%)	6/10 (60%)	8/8 (100%)
Muscle	2/8 (25%)	0/6 (0%)	6/8 (75%)
Stomach	0/8 (0%)	6/10 (60%)	8/8 (100%)
Duodenum	0/8 (0%)	10/10 (100%)	8/8 (100%)
Jejunum	0/6 (0%)	0/10 (0%)	6/8 (75%)
Ileum	0/8 (0%)	4/10 (40%)	6/8 (75%)
Cecum	0/8 (0%)	4/10 (40%)	6/8 (75%)
Proximal colon	0/8 (0%)	4/10 (40%)	6/8 (75%)
Colon distal	0/8 (0%)	4/10 (40%)	6/8 (75%)
Posterior leg
Skin	0/8 (0%)	4/10 (40%	6/8 (75%)
Muscle	0/8 (0%)	1/8 (12.5%)	8/8 (100%)
Bone	1/8 (12.5%)	3/8 (38%)	8/8 (100%)
Bone marrow	2/6 (33%)	5/10 (50%)	6/8 (75%)
Number of positive organs	15/136	70/166	128/144
Frequency	11%	42%	89%

Results are expressed as the number of mice (or percentage) with hMSC implantation in an organ (PCR positive for the gene for human 𝛽-globin) in comparison to the total number of mice injected with hMSCs. Day 0 of the kinetics of hMSC biodistribution corresponds to the day of irradiation. hMSCs were intravenously injected 24 hours after irradiation. hMSCs appear to migrate preferentially in the organs of the irradiated area; their implantation rate seems to be dose-dependent in these organs. hMSCs were not found in blood; 𝑛=10 (data are not shown).