Large scale platelet production from stem cells in microfluidic devices – PLASMIS

Platelets are essential to stop bleeding after vascular injury and to prevent hemorrhage. Patients with chemotherapy, bone marrow transplant or polytrauma display low platelet counts and require platelet transfusions. The only source of platelet concentrates (PC) comes from blood donors. However, steadily increasing needs in platelet transfusions, low blood product donation and a shelf life of PC of only 5 days result in a situation of severe tension, not to say shortage. Thus, the development of innovative processes is required.
Platelets are small anucleated cells, produced by terminal differentiation of mature megakaryocytes (MKs) in the bone marrow. The process of platelet generation and shedding from mature MKs occurs in the vascular space after migration of MKs into blood vessels where they are exposed to hemodynamic forces of the blood stream. As discovered by the coordinator, this physiological process can be reproduced in vitro by using experimental flow chambers coated with von Willebrand factor (VWF), a protein expressed by endothelial cells lining blood vessels. Although shown to be reliable and robust, in vitro platelet production remains a rather difficult challenge for 3 reasons:
1) So far the commercial flow device does not allow collecting all the platelets,
2) In vitro amplification of MKs remains low,
3) Platelets are prone to uncontrolled activation within a few hours.

The PLASMIS project aims at industrial development of a device suitable for large scale platelet production in vitro. The project is coordinated by the industrial partner (P1) PLATOD, a start-up recently founded by D. Baruch and J.J. Augier to improve platelet production in flow conditions. The scientific tasks will be accomplished through collaborations between 8 partners associated in this multidisciplinary consortium, bringing together experts in 3 fields:
1) Design of microfluidic systems: P2 is one of the leading laboratories of microfluidics that has just been selected to receive an Equipex and a Labex. He will be in charge of design and microfabrication of optimized microfluidic devices so as to increase yields of platelet production.
2) Production of MKs from native hematopoietic progenitor cells (HPC): amplification protocols of native MKs will be set up by P4, based on its strong expertise in HPC and their intracellular signaling pathways. While technologies will be developed by P3, a laboratory of worldwide reputation, to get platelet-producing MKs from new, homogenous and reproducible sources of cells as well as from human embryonic stem or induced pluripotent stem cell lines (ES or iPS) that can be highly amplified and overcome the variability in native HPC.
3) Characterization of platelets will be performed in vitro by platelet basic research experts (P5-P8), as well as in vivo by P5, who generated the model of VWF-deficient mice. Finally, quality controls and clinical applications to diagnostic tests will be performed by P6 and P7 who have major responsibilities in Hospital Haematology Departments. They will study the ability of these newly produced platelets to serve as reagent in diagnostic tests. This application will come more rapidly to the market than therapeutic applications.
P1, P4 and P5 have already been successful in the in vivo proof of concept of platelet production in flow conditions, during the PLASTHER project presently funded as an Emergence-Bio ANR project. The multidisciplinary approach of PLASMIS, by allowing the production of large quantities of platelets, is essential to the industrial strategy developed by PLATOD in order to gain a foothold on the transfusion market by answering to a growing need for more platelet concentrates, that is not presently dealt with, due to the decrease of blood donors.