TY - JOUR T1 - Mesenchymal Stromal Cell Delivery via an Ex Vivo Bioreactor Preclinical Test System Attenuates Clot Formation for Intravascular Application JF - bioRxiv DO - 10.1101/2020.11.20.391631 SP - 2020.11.20.391631 AU - Brian O’Rourke AU - Sunny Nguyen AU - Arno W. Tilles AU - James A. Bynum AU - Andrew P Cap AU - Biju Parekkadan AU - Rita N. Barcia Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/11/24/2020.11.20.391631.abstract N2 - While mesenchymal stromal cells (MSCs) are an appealing therapeutic option for a range of clinical applications, their potential to induce clotting when used systemically remains a safety concern, particularly in hypercoagulable conditions, such as in patients with severe COVID-19, trauma, or cancers. Here, we tested a novel ex vivo approach aimed at improving the safety of MSC systemic administration by use of a bioreactor. In this device, MSCs are seeded on the outside of a hollow-fiber filter, sequestering them behind a hemocompatible membrane, while still maintaining cross talk with blood cells and circulating signaling molecules. The potential for these bioreactor MSCs to induce clots in coagulable plasma was compared against “free” MSCs, as a model of systemic administration, which were directly injected into the circuit. Our results showed that physical isolation of the MSCs via a bioreactor extends the time necessary for clot formation to occur when compared to “free” MSCs. Measurement of cell surface data indicates the presence of known clot inducing factors, namely tissue factor and phosphatidylserine. Results also showed that recovering cells and flushing the bioreactor prior to use further prolonged clot formation time. Further, application of this technology in two in vivo models did not require additional heparin to maintain target ACT levels relative to the acellular device. Taken together, the use of hollow fiber filters to house MSCs, if adopted clinically, could offer a novel method to control systemic MSC exposure and prolong clot formation time.Competing Interest StatementThe opinions or assertions contained herein are the private views of the author and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense. JB and AC are United States government employees with no financial disclosures relevant to this publication. BOR, SN, AT, RNB are employees and equity shareholders of Sentien Biotechnologies. BP is an equity shareholder and inventor of the technology with licensed patents to Sentien for commercialization. ER -