Macrophage inflammatory protein-1 alpha (MIP-1 alpha) is a chemokine that has pro-inflammatory and stem cell inhibitory activities in vitro. Its biologic role in vivo was examined in mice in which the gene encoding MIP-1 alpha had been disrupted. Homozygous MIP-1 alpha mutant (-/-) mice were resistant to Coxsackievirus-induced myocarditis seen in infected wild-type (+/+) mice. Influenza virus-infected -/- mice had reduced pneumonitis and delayed clearance of the virus compared with infected +/+ mice. The -/- mice had no overt hematopoietic abnormalities. These results demonstrate that MIP-1 alpha is an important mediator of virus-induced inflammation in vivo.

In multiple myeloma, karyotypic 14q32 translocations have been identified at a variable frequency (10-60% in different studies). In the majority of cases, the partner chromosome has not been identified (14q؉), and in the remaining cases, a diverse array of chromosomal partners has been implicated, with 11q13 being the most common. We developed a comprehensive Southern blot assay to identify and distinguish different kinds of immunoglobulin heavy chain (IgH) switch recombination events. Illegitimate switch recombination fragments (defined as containing sequences from only one switch region) are potential markers of translocation events into IgH switch regions and were identified in 15 of 21 myeloma cell lines, including seven of eight karyotyped lines that have no detectable 14q32 translocation. From all nine lines or tumor samples analyzed further, cloned illegitimate switch recombination fragments were confirmed to be IgH switch translocation breakpoints. In three of these cases, the translocation breakpoint was shown to be present in the primary tumor. These translocation breakpoints involve six chromosomal loci: 4p16.3 (two lines and the one tumor); 6; 8q24.13; 11q13.3 (in three lines); 16q23.1; and 21q22.1. We suggest that translocations into the IgH locus (i) are frequent (karyotypic 14q32 translocations and͞or illegitimate switch recombination fragments are present in primary tumor samples and in 19 of 21 lines that we have analyzed); (ii) occur mainly in switch regions; and (iii) involve a diverse but nonrandom array (i.e., frequently 11q13 or 4p16) of chromosomal partners. This appears to be the most frequent genetic abnormality in multiple myeloma.

We have used a "plug and socket" targeting technique to generate a mouse model of 130-thalassemia

The coordinated expression of chemokines and receptors may be important in the directed migration of alloreactive T cells during graft-vs-host disease (GVHD). Recent work demonstrated in a murine model that transfer of CCR5-deficient (CCR5−/−) donor cells to nonconditioned haploidentical recipients resulted in reduced donor cell infiltration in liver and lymphoid tissues compared with transfer of CCR5+/+ cells. To investigate the function of CCR5 during GVHD in conditioned transplant recipients, we transferred CCR5−/− or wild-type C57BL/6 (B6) T cells to lethally irradiated B6D2 recipients. Unexpectedly, we found an earlier time to onset and a worsening of GVHD using CCR5−/− T cells, which was associated with significant increases in the accumulation of alloreactive CD4+ and CD8+ T cells in liver and lung. Conversely, the transfer of CCR5−/− donor cells to nonirradiated recipients led to reduced infiltration of target organs, confirming previous studies and demonstrating that the role of CCR5 on donor T cells is dependent on conditioning of recipients. Expression of proinflammatory chemokines in target tissues was dependent on conditioning of recipients, such that CXCL10 and CXCL11 were most highly expressed in tissues of irradiated recipients during the first week post-transplant. CCR5−/− T cells were shown to have enhanced migration to CXCL10, and blocking this ligand in vivo improved survival in irradiated recipients receiving CCR5−/− T cells. Our data indicate that the effects of inhibiting CCR5/ligand interaction on donor T cells during GVHD differ depending on conditioning of recipients, a finding with potentially important clinical significance.

Our recent gene expression profiling analyses demonstrated that Wnt2 is highly expressed in Flk1؉ cells, which serve as common progenitors of endothelial cells, blood cells, and mural cells. In this report, we characterize the role of Wnt2 in mesoderm development during embryonic stem (ES) cell differentiation by creating ES cell lines in which Wnt2 was deleted. Wnt2؊/؊ embryoid bodies (EBs) generated increased numbers of Flk1؉ cells and blast colony-forming cells compared with wild-type EBs, and had higher Flk1 expression at comparable stages of differentiation. Although Flk1 ؉ cells were increased, we found that endothelial cell and terminal cardiomyocyte differentiation was impaired, but hematopoietic cell differentiation was enhanced and smooth muscle cell differentiation was unchanged in Wnt2 ؊/؊ EBs. Later stage Wnt2 ؊/؊ EBs had either lower or undetectable expression of endothelial and cardiac genes compared with wild-type EBs. Consistently, vascular plexi were poorly formed and neither beating cardiomyocytes nor ␣-actinin-staining cells were detectable in later stage Wnt2 ؊/؊ EBs. In contrast, hematopoietic cell gene expression was upregulated, and the number of hematopoietic progenitor colonies was significantly enhanced in Wnt2 ؊/؊ EBs. Our data indicate that Wnt2 functions at multiple stages of development during ES cell differentiation and during the commitment and diversification of mesoderm: as a negative regulator for hemangioblast differentiation and hematopoiesis but alternatively as a positive regulator for endothelial and terminal cardiomyocyte differentiation. Embryonic stem (ES)2 cells have considerable potential for use in cellular therapies for many human diseases or disorders.However, manipulating the differentiation of pluripotent cells into a desired cell type is difficult to control. Therefore, efforts have been directed toward understanding the molecular and cellular mechanisms for maintaining ES cell pluripotency as well as for ES cell fate determination and lineage specification. Under appropriate culture conditions, ES cells will spontaneously differentiate and form embryoid bodies (EBs) that recapitulate the differentiation program of normal embryonic development. This in vitro experimental model is widely used to study mesoderm development, including the hematopoietic system, vascular endothelial cells, and cardiomyocytes (1-4).Murine hematopoietic and endothelial cell development begins in the yolk sac mesoderm at approximately day 7.5 of gestation and is marked by establishment of blood islands (5, 6). The close physical relationship between these two cell populations within blood islands has led to a widely accepted hypothesis that a common precursor for both hematopoietic and endothelial cells exists, the hemangioblast (7, 8). The receptor for vascular endothelial growth factor (VEGF), fetal liver kinase-1 (Flk1), is an early molecular marker for hemangioblasts (9 -12). Blast colony-forming cells (BLCFCs) derived from EBs can generate hematopoietic and endothelial cell lineag...