Distribution pattern following systemic mesenchymal stem cell injection depends on the age of the recipient and neuronal health

BACKGROUND: Mesenchymal stem cells (MSCs) show therapeutic efficacy in many different age-related degenerative diseases, including Alzheimer's disease. Very little is currently known about whether or not aging impacts the transplantation efficiency of MSCs. METHODS: In this study, we investigated the distribution of intravenously transplanted syngeneic MSCs derived from young and aged mice into young, aged, and transgenic APP/PS1 Alzheimer's disease mice. MSCs from male donors were transplanted into female mice and their distribution pattern was monitored by PCR using Y-chromosome specific probes. Biodistribution of transplanted MSCs in the brains of APP/PS1 mice was additionally confirmed by immunofluorescence and confocal microscopy. RESULTS: Four weeks after transplantation into young mice, young MSCs were found in the lung, axillary lymph nodes, blood, kidney, bone marrow, spleen, liver, heart, and brain cortex. In contrast, young MSCs that were transplanted into aged mice were only found in the brain cortex. In both young and aged mouse recipients, transplantation of aged MSCs showed biodistribution only in the blood and spleen. Although young transplanted MSCs only showed neuronal distribution in the brain cortex in young mice, they exhibited a wide neuronal distribution pattern in the brains of APP/PS1 mice and were found in the cortex, cerebellum, hippocampus, olfactory bulb, and brainstem. The immunofluorescent signal of both transplanted MSCs and resident microglia was robust in the brains of APP/PS1 mice. Monocyte chemoattractant-1 levels were lowest in the brain cortex of young mice and were significantly increased in APP/PS1 mice. Within the hippocampus, monocyte chemoattractant-1 levels were significantly higher in aged mice compared with younger and APP/PS1 mice. CONCLUSIONS: We demonstrate in vivo that MSC biodistribution post transplantation is detrimentally affected by aging and neuronal health. Aging of both the recipient and the donor MSCs used attenuates transplantation efficiency. Clinically, our data would suggest that aged MSCs should not be used for transplantation and that transplantation of MSCs into aged patients will be less efficacious

Biodistribution of in vitro-derived microglia applied intranasally and intravenously to mice: effects of aging

Background aims. The age of both the donor and the recipient has a potential influence on the efficacy of various cell therapies, but the underlying mechanisms are still being charted. We studied the effect of donor and recipient age in the context of microglia migration. Methods. Microglia were in vitroedifferentiated from bone marrow of young (3 months) and aged (12 months) mice and transplanted into young (w3 months) and aged (w17 months) C57BL/6 mice (n ¼ 25) through intravenous and intranasal application routes. Recipients were not immune-suppressed or irradiated. Transplanted microglia were tracked through the use of a sex-mismatched setup or histologically with the use of cells from enhanced green fluorescent protein enhanced green fluorescent protein transgenic mice. Results. No acute rejections or transplant-associated toxicity was observed. After 10 days, both intravenously and intranasally transplanted cells were detected in the brain. Transplanted cells were also found in the blood and the lymph system. The applied cells were also tracked in lungs and kidney but only after intravenous injection subjected to a “pulmonary first-pass effect.” After 28 days, intravenously delivered cells were also found in the bone marrow and other organs, especially in aged recipients. Whereas in young recipients the transplanted microglia did not appear to persist, in aged brains the transplanted cells could still be identified up to 28 days after transplantation. However, when cells from aged donors were used, no signals of transplanted cells could be detected in the recipients. Conclusions. This study establishes proof of principle that in vitroederived microglia from young but not from aged donors, intravenously or intranasally transplanted, migrate to the brain in young and aged recipients

Additional file 1: Figure S1. of Distribution pattern following systemic mesenchymal stem cell injection depends on the age of the recipient and neuronal health

showing mesodermal lineage differentiation of bone-marrow-derived MSCs. Bone-marrow-derived MSCs were differentiated in vitro under adipogenic (a), osteogenic (b), or chondrogenic (c) conditions. Verification of the differentiation was done by qualitative analysis: adipogenesis shown by staining lipid vesicles with Oil red-O (a), osteogenesis shown by staining alkaline phosphatase with Fast Red (b), and chondrogenesis shown by staining sulphated proteoglycans typical for extracellular matrix composition with Alcian Blue under acidic conditions

Biodistribution of in vitro-derived microglia applied intranasally and intravenously to mice: effects of aging

Background aims. The age of both the donor and the recipient has a potential influence on the efficacy of various cell therapies, but the underlying mechanisms are still being charted. We studied the effect of donor and recipient age in the context of microglia migration. Methods. Microglia were in vitroedifferentiated from bone marrow of young (3 months) and aged (12 months) mice and transplanted into young (w3 months) and aged (w17 months) C57BL/6 mice (n ¼ 25) through intravenous and intranasal application routes. Recipients were not immune-suppressed or irradiated. Transplanted microglia were tracked through the use of a sex-mismatched setup or histologically with the use of cells from enhanced green fluorescent protein enhanced green fluorescent protein transgenic mice. Results. No acute rejections or transplant-associated toxicity was observed. After 10 days, both intravenously and intranasally transplanted cells were detected in the brain. Transplanted cells were also found in the blood and the lymph system. The applied cells were also tracked in lungs and kidney but only after intravenous injection subjected to a “pulmonary first-pass effect.” After 28 days, intravenously delivered cells were also found in the bone marrow and other organs, especially in aged recipients. Whereas in young recipients the transplanted microglia did not appear to persist, in aged brains the transplanted cells could still be identified up to 28 days after transplantation. However, when cells from aged donors were used, no signals of transplanted cells could be detected in the recipients. Conclusions. This study establishes proof of principle that in vitroederived microglia from young but not from aged donors, intravenously or intranasally transplanted, migrate to the brain in young and aged recipients

Additional file 2: Figure S2. of Distribution pattern following systemic mesenchymal stem cell injection depends on the age of the recipient and neuronal health

showing cell marker panels of Sca1, CD73, CD105, CD29, and CD45 in bone-marrow derived MSCs. A cell marker panel was performed via FACS on Bl6, bone-marrow-derived MSCs at passage 3. P2-Q4 represents the negative quadrant in the bottom left (purple). P2-Q1 represents the positive quadrant in the upper left (green). (TIF 1142 kb

Additional file 3: Figure S3. of Distribution pattern following systemic mesenchymal stem cell injection depends on the age of the recipient and neuronal health

showing cell marker panels of CD11b, CD106, and CD44 in bone-marrow-derived MSCs. A cell marker panel was performed via FACS on Bl6, bone-marrow-derived MSCs at passage 3. P2-Q4 represents the negative quadrant in the bottom left (purple). P2-Q1 represents the positive quadrant in the upper left (green). Bar graph (bottom right) and textual table (bottom left) included to summarize the overall results of the FACS experiments. (TIF 831 kb

Additional file 4: Figure S4. of Distribution pattern following systemic mesenchymal stem cell injection depends on the age of the recipient and neuronal health

showing a low-magnification image of transplanted MSCs in the brain of APP/PS1 mice. Representative low-magnification image showing the migration of transplanted GFP-positive MSCs (green) into the brains of APP/PS1 mice. GFP-expressing MSCs were found in association with activated microglia (Iba-1, red). Sections were stained with DAPI to highlight nuclei as a positional marker. Scale bar: 50 μM. (TIF 4445 kb