Avian HSC emergence, migration, and commitment toward the T cell lineage

Ka-mi-kae-kyuk-tang oriental herbal cocktail attenuates cyclophosphamide-induced leukopenia side effects in mouse

Ka-mi-kae-kyuk-tang (KMKKT) is an Oriental herbal medicinal cocktail and has been shown to have potent antiangiogenic, anticancer, and antimetastatic activities in preclinical animal models without observable side effects. We previously found that in prostate cancer xenograft experiments, treating tumor-bearing mice with KMKKT alleviated the body weight loss toward the end of the study, suggesting a general health-promoting activity. We investigated whether KMKKT alleviated cancer chemotherapy drug-induced leukopenia and other hematotoxicity in vivo using a mouse model. KMKKT was given once daily orally for 10 days to the mice before they were given cyclophosphamide (CPA) daily injection for 4 days. KMKKT blunted CPA-induced decrease in red blood cells, hemoglobin content, and the total white blood cell/leukocyte counts. Examination of the multiple organ sites involved in hematopoiesis, and lymphocyte differentiation and maturation showed the attenuated changes induced by CPA in each and every type of cells examined. Particularly, some of the cell types are fully restored in the bone marrow and even overstimulated in the Sca-1(+), CD117(+), or Sca1(+)/CD117(+) and CD34(+)/CD117(+) stem cells, supporting a role of KMKKT to stimulate hematopoietic stem cell (HSC) signaling to compensate for CPA-induced destruction of leukocytes and other cell types. Taken together, KMKKT might be a safe and effective herbal complementary and alternative medicine (CAM) modality to alleviate cancer drug-induced hematological side effects in addition to its anticancer activities. Preclinical investigations with other chemo- and radiation modalities are warranted to support planning translation consideration for human patients.

CD41+ cmyb+ precursors colonize the zebrafish pronephros by a novel migration route to initiate adult hematopoiesis

Development of the vertebrate blood lineages is complex, with multiple waves of hematopoietic precursors arising in different embryonic locations. Monopotent, or primitive, precursors first give rise to embryonic macrophages or erythrocytes. Multipotent, or definitive, precursors are subsequently generated to produce the adult hematopoietic lineages. In both the zebrafish and the mouse, the first definitive precursors are committed erythromyeloid progenitors (EMPs) that lack lymphoid differentiation potential. We have previously shown that zebrafish EMPs arise in the posterior blood island independently from hematopoietic stem cells (HSCs). In this report, we demonstrate that a fourth wave of hematopoietic precursors arises slightly later in the zebrafish aorta/gonad/mesonephros (AGM) equivalent. We have identified and prospectively isolated these cells by CD41 (itga2b) and cmyb expression. Unlike EMPs, CD41(+) AGM cells colonize the thymus to generate rag2(+) T lymphocyte precursors. Timelapse imaging and lineage tracing analyses demonstrate that AGM-derived precursors use a previously undescribed migration pathway along the pronephric tubules to initiate adult hematopoiesis in the developing kidney, the teleostean equivalent of mammalian bone marrow. Finally, we have analyzed the gene expression profiles of EMPs and AGM precursors to better understand the molecular cues that pattern the first definitive hematopoietic cells in the embryo. Together, these studies suggest that expression of CD41 and cmyb marks nascent HSCs in the zebrafish AGM, and provide the means to further dissect HSC generation and function in the early vertebrate embryo.