Cellerant researchers worked with specialized mice prone to an autoimmune condition closely resembling human SLE. The lupus-like disease in these mice is a T-cell dependent autoimmune disease with a loss of suppressor-cell function, polyclonal B-cell activation, and abnormalities of phagocytic cells and complement. The donors and recipients in this study were haplomismatched, yet successful engraftment was achieved and graft-versus-host disease (GVHD) was avoided.

The study evaluated both nonablative conditioning, which leaves the recipient's immune system intact, and fully myeloablative conditioning, which eradicates the recipient's immune system, prior to purified HSC treatment. Traditionally, full, and potentially lethal, myeloablative treatment was considered critical for engraftment success. The researchers found that nonablative conditioning prior to HSC treatment was not only sufficient to ensure engraftment, but the procedure resulted in improved overall survival. The recipient mice developed durable mixed chimerism, where the resulting immune system was a mixture of donor and recipient cells. SLE mice with established autoimmune disease experienced a stabilization or reversal of their lupus symptoms as measured by reduced proteinuria and reduced circulating immune complexes and auto-antibodies to nuclear antigens, as compared with untreated control mice, lymphoablated mice, or mice transplanted with syngeneic cells. These results suggest that the use of HSC preparations that have been purified of all or most T-cells and natural killer cells may eliminate the need for complete donor/patient stem cell matching.

Cellerant's highly purified HSC are isolated from donors or patients undergoing stem cell transplants. This process is designed to provide an improved outcome in stem cell transplant indications where a high level of purity is desired or required. After purification, this material contains only stem and progenitor cells, with no detectable contaminating cells such as tumor cells or the T-cells that cause GVHD in donor-to-patient transplants. Cellerant is developing HSC for autoimmune disease, cancer, and genetic blood disorders.

—A. Techman

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