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Using Proteomics Analysis to Identify Novel Proteins in Marrow Niche Microenvironment That Contribute to the Enhanced Donor Cell Engraftment with Plerixafor Treatment

Year: 2012

Type: article

Abstract: Enhancing donor cell recovery is a very important goal in hematopoietic stem cell transplantation (HCT). Hematopoiesis is regulated by marrow niche microenvironment. We recently found that post transplant administration of plerixafor (a specific and reversible CXCR4 antagonist) enhanced donor cell engraftment and promoted recovery of all donor cell lineages in a congeneic mouse transplant model (Kang et al, 2010, PLoS One 5, e11316). We hypothesized that plerixafor enhances donor cell reconstitution in part by modulating the levels and constitution of soluble factors in niche microenvironment. To test this hypothesis, we transplanted lethally irradiated C57Bl/6 mice with sorted c-Kit+ Lin- Sca-1+ HSCs and then injected s.c. PBS or plerixafor (5 mg/kg) every other day beginning at day +2 post transplant. At day +7 post transplant, the mice were sacrificed. Tibias and femurs were flushed with PBS, centrifuged, and marrow supernatants were collected. We found that the marrow supernatants of PBS treated- transplant mice inhibited bone marrow cell (BMC) colony forming units (CFUs). In contrast, the marrow supernatants of plerixafor treated- mice significantly increased BMC CFUs, and plerixafor per se had no effects on CFUs. We next used a mass spectrometry-based, quantitative, label-free proteomics approach to compare the protein expression in marrow supernatant of PBS treated- transplant mice with that from plerixafor treated- mice. We identified a total of 289 proteins, 3 of them only present in the marrow supernatants of PBS treated- transplant mice. Twenty-three proteins were increased (more than 2 fold) and 7 decreased in plerixafor treated- transplant mice. We then performed additional studies to validate our proteomics results. We focused on thioredoxin, one of the 23 proteins that increased in the marrow supernatant of plerixafor treated- transplant mice. Thioredoxin is a small oxidoreductase protein important in preserving tissue redox homeostasis and cellular integrity. We found that thioredoxin mRNA expression in BMCs was up-regulated with plerixafor treatment. Furthermore, we found that thioredoxin increased BMC CFUs, enhanced recovery of platelet count in sublethally irradiated mice, and protected against radiation-related death. Our results demonstrated that factors in the marrow niche microenvironment play a critical role in hematopoiesis. Our study provides clue on potential novel targets that can be used to further enhance hematopoiesis.

Source: Transplantation and Cellular Therapy

DOI: 10.1016/j.bbmt.2011.12.499