Source Paper
Thorsten R. Doeppner, Josephine Herz, André Görgens, Jana Schlechter, Anna-Kristin Ludwig et al.
Stem Cells Translational Medicine • 2015
Abstract Although the initial concepts of stem cell therapy aimed at replacing lost tissue, more recent evidence has suggested that stem and progenitor cells alike promote postischemic neurological recovery by secreted factors that restore the injured brain's capacity to reshape. Specifically, extracellular vesicles (EVs) derived from stem cells such as exosomes have recently been suggested to mediate restorative stem cell effects. In order to define whether EVs indeed improve postischemic neurological impairment and brain remodeling, we systematically compared the effects of mesenchymal stem cell (MSC)-derived EVs (MSC-EVs) with MSCs that were i.v. delivered to mice on days 1, 3, and 5 (MSC-EVs) or on day 1 (MSCs) after focal cerebral ischemia in C57BL6 mice. For as long as 28 days after stroke, motor coordination deficits, histological brain injury, immune responses in the peripheral blood and brain, and cerebral angiogenesis and neurogenesis were analyzed. Improved neurological impairment and long-term neuroprotection associated with enhanced angioneurogenesis were noticed in stroke mice receiving EVs from two different bone marrow-derived MSC lineages. MSC-EV administration closely resembled responses to MSCs and persisted throughout the observation period. Although cerebral immune cell infiltration was not affected by MSC-EVs, postischemic immunosuppression (i.e., B-cell, natural killer cell, and T-cell lymphopenia) was attenuated in the peripheral blood at 6 days after ischemia, providing an appropriate external milieu for successful brain remodeling. Because MSC-EVs have recently been shown to be apparently safe in humans, the present study provides clinically relevant evidence warranting rapid proof-of-concept studies in stroke patients. Significance Transplantation of mesenchymal stem cells (MSCs) offers an interesting adjuvant approach next to thrombolysis for treatment of ischemic stroke. However, MSCs are not integrated into residing neural networks but act indirectly, inducing neuroprotection and promoting neuroregeneration. Although the mechanisms by which MSCs act are still elusive, recent evidence has suggested that extracellular vesicles (EVs) might be responsible for MSC-induced effects under physiological and pathological conditions. The present study has demonstrated that EVs are not inferior to MSCs in a rodent stroke model. EVs induce long-term neuroprotection, promote neuroregeneration and neurological recovery, and modulate peripheral post-stroke immune responses. Also, because EVs are well-tolerated in humans, as previously reported, the administration of EVs under clinical settings might set the path for a novel and innovative therapeutic stroke concept without the putative side effects attached to stem cell transplantation.
Objective: To compare the effects of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) with MSCs delivered intravenously after focal cerebral ischemia, measuring motor coordination deficits, brain injury, immune responses, angiogenesis, and neurogenesis
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Focal cerebral ischemia was induced in C57BL6 mice
Note: This is the baseline stroke induction procedure
“focal cerebral ischemia in C57BL6 mice”
Intravenous delivery of MSC-derived extracellular vesicles on day 1 after focal cerebral ischemia
Note: First treatment timepoint
“i.v. delivered to mice on days 1, 3, and 5 (MSC-EVs)”
Intravenous delivery of MSC-derived extracellular vesicles on day 3 after focal cerebral ischemia
Note: Second treatment timepoint
“i.v. delivered to mice on days 1, 3, and 5 (MSC-EVs)”
Intravenous delivery of MSC-derived extracellular vesicles on day 5 after focal cerebral ischemia
Note: Third treatment timepoint
“i.v. delivered to mice on days 1, 3, and 5 (MSC-EVs)”
Intravenous delivery of mesenchymal stem cells on day 1 after focal cerebral ischemia as control treatment
Note: Control group receiving MSCs instead of EVs
“on day 1 (MSCs) after focal cerebral ischemia”
Motor coordination deficits were analyzed throughout the observation period
Note: Measured at multiple timepoints up to 28 days
“For as long as 28 days after stroke, motor coordination deficits, histological brain injury”
Histological analysis of brain injury was performed
Note: Measured at multiple timepoints up to 28 days
“motor coordination deficits, histological brain injury, immune responses in the peripheral blood and brain”
Immune responses including B-cell, natural killer cell, and T-cell lymphopenia were analyzed in peripheral blood
Note: Postischemic immunosuppression was assessed
“postischemic immunosuppression (i.e., B-cell, natural killer cell, and T-cell lymphopenia) was attenuated in the peripheral blood at 6 days after ischemia”
Immune cell infiltration and immune responses were analyzed in brain tissue
Note: Cerebral immune cell infiltration was measured
“immune responses in the peripheral blood and brain, and cerebral angiogenesis and neurogenesis”
Cerebral angiogenesis was analyzed as a measure of brain remodeling
Note: Enhanced angioneurogenesis was observed in treatment groups
“cerebral angiogenesis and neurogenesis were analyzed”
Neurogenesis was analyzed as a measure of brain remodeling and recovery
Note: Enhanced angioneurogenesis was observed in treatment groups
“cerebral angiogenesis and neurogenesis were analyzed”
Focal cerebral ischemia was induced in mice