Abstract TMP118: Brain Derived Neurotrophic Factor Secretion From Lungs Mediate The Post-stroke Functional Recovery After Systemic Administration Of MSCs

Background: Bone marrow derived mesenchymal stromal cells (MSCs) have been actively tested in clinical trials. After intravenous (IV) administration, vast majority of them are trapped in lung vasculature, with only few reaching brain. Even though MSCs are short-lived in the lungs, their beneficial effects on post-stroke recovery extends for weeks, suggesting a paracrine mechanism of action. Integrins expression on MSCs is known to mediate the lung entrapment by binding to ICAM1-expressing endothelial cells (ECs). Furthermore, ECs can perform paracrine functions by releasing neurotrophins, such as brain derived neurotrophic factor (BDNF). We explored EC-MSC interaction in lungs, and its effect on BDNF release from lung ECs, in an experimental stroke model. Methods: Human lung ECs (Cell Biologics) were cultured at P3. Human MSCs were isolated from bone marrow of healthy donor and P3 MSCs were used for experiments. Serum from stroke patients with NIH Stroke Scale (NIHSS) severity ranging from 0 to 10 was collected at 24 hours after stroke. Co-culture experiments were done in trans-well plates. BDNF mRNA was isolated using Qiagen RNeasy kit. Middle Cerebral Artery Occlusion model (filament model) was used in C57BL/6 mice. Modified Neurological Severity Score (mNSS) was used for functional assessment in mice stroke model. Results: Human primary lung ECs exposed to plasma from stroke patients as well as recombinant TNF-α showed robust increase in BDNF secretion, with MSCs enhancing the secretion furthermore. BDNF mRNA was robustly increased in whole mouse lungs as well as lung ECs. IV MSC administration robustly increased plasma BDNF and BDNF mRNA expression in mouse lung ECs. Furthermore, IV MSCs provided better functional recovery as compared to IV BDNF. Conclusion: BDNF is already known to be neuroprotective. Our results show that BDNF secretions increase from lung ECs after IV MSC administration, which could mediate functional recovery in mice after stroke.