Developing a bank of purified myeloid progenitor cells as a bridging therapy for transient pancytopenia resulting from radiation injury

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ABSTRACT Exposure to even moderate levels (<3 Gy) of ionizing radiation can result in severe pancyotopenia, placing patients as wells as victims of accidental exposure at high risks for infection and uncontrolled hemorrhaging. Accidental exposure differs from radiation therapy in that biodosimetry (e.g., type of radiation, dose and dose rate) is often uncertain; consequently, the optimal treatment regimen to ameliorate the effects of radiation is not immediately evident. Therefore, victims of accidental ionizing radiation exposure would benefit from bridging therapies to traverse extended periods of neutropenia and thrombocytopenia until the optimal course of medical care can be determined. Ossium Health proposes to develop a bank of myeloid progenitor cells (MPC) from deceased donor bone marrow (BM). The strategy employs commercially available immunomagnetic selection reagents and clinical-scale closed-system semi-automated devices to specific select MPC from whole BM based on defining cell surface markers CD34+CD38+. The proposed Phase I studies build on our previous success with selecting large numbers (>150 million) of stem and progenitor cells from organ donor BM. We will evaluate combinations of selection, depletion and ablation to purify MPC without contaminating T cells long-term repopulating stem cells to prevent graft versus host disease. The cells will be validated in vitro and in vivo in a mouse xenotransplantation study to evaluate reestablishment of short-term innate immunity. The overall product of this research program will be a compelling preclinical package to justify definitive studies to support FDA approval under the Animal Rule for a novel radiation/nuclear mass casualty medical countermeasure bridging therapy. Future commercial viability for both medical countermeasures and civilian uses is enhanced by the up to 5-fold lower cost for manufacturing compared to current technologies.