Transfer Of Bone Marrow Cells Research Articles

A Novel Microsurgical Model for Heterotopic, En Bloc Chest Wall, Thymus, and Heart Transplantation in Mice

Exploration of novel strategies in organ transplantation to prolong allograft survival and minimizing the need for long-term maintenance immunosuppression must be pursued. Employing vascularized bone marrow transplantation and co-transplantation of the thymus have shown promise in this regard in various animal models.1-11 Vascularized bone marrow transplantation allows for the uninterrupted transfer of donor bone marrow cells within the preserved donor microenvironment, and the incorporation of thymus tissue with vascularized bone marrow transplantation has shown to increase T-cell chimerism ultimately playing a supportive role in the induction of immune regulation. The combination of solid organ and vascularized composite allotransplantation can uniquely combine these strategies in the form of a novel transplant model. Murine models serve as an excellent paradigm to explore the mechanisms of acute and chronic rejection, chimerism, and tolerance induction, thus providing the foundation to propagate superior allograft survival strategies for larger animal models and future clinical application. Herein, we developed a novel heterotopic en bloc chest wall, thymus, and heart transplant model in mice using a cervical non-suture cuff technique. The experience in syngeneic and allogeneic transplant settings is described for future broader immunological investigations via an instructional manuscript and video supplement.

Ly6Chigh Monocytes Protect against Kidney Damage during Sepsis via a CX3CR1-Dependent Adhesion Mechanism

Monocytes have a crucial role in both proinflammatory and anti-inflammatory phenomena occurring during sepsis. Monocyte recruitment and activation are orchestrated by the chemokine receptors CX3CR1 and CCR2 and their cognate ligands. However, little is known about the roles of these cells and chemokines during the acute phase of inflammation in sepsis. Using intravital microscopy in a murine model of polymicrobial sepsis, we showed that inflammatory Ly6C(high) monocytes infiltrated kidneys, exhibited altered motility, and adhered strongly to the renal vascular wall in a chemokine receptor CX3CR1-dependent manner. Adoptive transfer of Cx3cr1-proficient monocyte-enriched bone marrow cells into septic Cx3cr1-depleted mice prevented kidney damage and promoted mouse survival. Modulation of CX3CR1 activation in septic mice controlled monocyte adhesion, regulated proinflammatory and anti-inflammatory cytokine expression, and was associated with the extent of kidney lesions such that the number of lesions decreased when CX3CR1 activity increased. Consistent with these results, the pro-adhesive I249 CX3CR1 allele in humans was associated with a lower incidence of AKI in patients with sepsis. These data show that inflammatory monocytes have a protective effect during sepsis via a CX3CR1-dependent adhesion mechanism. This receptor might be a new therapeutic target for kidney injury during sepsis.

Autonomic dysfunction determines stress-induced cardiovascular and immune complications in mice.

BackgroundClinical studies suggest that acute inflammation in patients with elevated heart rate (HR) increases morbidity and mortality. The SJL/J (SJL) inbred mouse strain is a unique genetic model that has higher HR and systemic and vascular inflammation compared with C3HeB/FeJ (C3HeB) mice. The goal of this study was to investigate the role of stress on cardiac and vascular complications between 2 strains.Methods and ResultsRadiotelemetry was used for continuous recordings of HR and blood pressure in mice. Hemodynamic differences between mouse strains were very small without stress; however, tail-cuff training generated mild stress and significantly increased HR (≈2-fold) in SJL compared with C3HeB mice. Circulating proinflammatory monocytes (CD11b+Ly6CHi) significantly increased in SJL mice but not in C3HeB mice after stress. Presence of Ly6C+ cells in injured carotids was elevated only in SJL mice after stress; however, a transfer of bone marrow cells from SJL/C3HeB to C3HeB/SJL chimeras had no effect on HR or vascular inflammation following stress. Arterial inflammation (VCAM-1+) was greater in SJL inbred mice or SJL recipient chimeras, even without stress or injury. HR variability was reduced in SJL mice compared with C3HeB mice.ConclusionsWe found that impaired parasympathetic activity is central for stress-induced elevation of HR and systemic and vascular inflammation; however, immune cells from stress-susceptible mice had no effect on HR or vascular inflammation in stress-protected mice.

Molecular mechanism underlying immune modulation during stem cell therapy of overt type 1 diabetes (THER5P.917)

Abstract Type 1 diabetes (T1D) is an autoimmune disorder in which insulin-producing pancreatic beta-cells are selectively destroyed by self-reactive T cells. In previous studies, we incorporated glutamic acid decarboxylase 206-220 peptide into an Ig molecule and the resulting Ig-GAD2 chimera was shown to target diabetogenic T cells and prevent disease progression. However, despite its efficacy, Ig-GAD2 was not able to reverse overt T1D. In contrast, transfer of bone marrow (BM) cells alongside Ig-GAD2 induces recovery from overt T1D. This was due to effective immune modulation that stems from diminished function of the mammalian target of rapamycin (mTOR) complex 1. In addition, there was generation of BM-derived endothelial cells that contributed to the repair of islet vascular network which facilitated endogenous β-cell formation and restoration of β-cell mass. These findings suggest that targeting the function of mTOR synergizes with stem cell transfer to control overt T1D.

Aromatase Controls Sjögren Syndrome–Like Lesions through Monocyte Chemotactic Protein-1 in Target Organ and Adipose Tissue–Associated Macrophages

Several autoimmune diseases are known to develop in postmenopausal women. However, the mechanism by which estrogen deficiency influences autoimmunity is unknown. Aromatase is an enzyme that converts androgens to estrogens. Herein, we used female aromatase gene knockout (ArKO) mice as a model of estrogen deficiency to investigate the molecular mechanism that underlies the onset and development of autoimmunity. Histological analyses showed that inflammatory lesions in the lacrimal and salivary glands of ArKO mice increased with age. Adoptive transfer of spleen cells or bone marrow cells from ArKO mice into recombination activating gene 2 knockout mice failed to induce the autoimmune lesions. Expression of mRNA encoding proinflammatory cytokines and monocyte chemotactic protein-1 increased in white adipose tissue of ArKO mice and was significantly higher than that in wild-type mice. Moreover, an increased number of inflammatory M1 macrophages was observed in white adipose tissue of ArKO mice. A significantly increased monocyte chemotactic protein-1 mRNA expression of the salivary gland tissue in ArKO was found together with adiposity. Furthermore, the autoimmune lesions in a murine model of Sjögren syndrome were exacerbated by administration of an aromatase inhibitor. These results suggest that aromatase may play a key role in the pathogenesis of Sjögren syndrome-like lesions by controlling the target organ and adipose tissue-associated macrophage.

Myeloid suppressor cells require membrane TNFR2 expression for suppressive activity.

TNF and TNF receptor type 2 (TNFR2) have been shown to be important for generation of myeloid-derived suppressor cells (MDSC). In order to analyze whether and how TNFR2 passes the effect of TNF on, myeloid cells from TNFR2-deficient mice were compared to respective cells from wild-type mice. Primary TNFR2-deficient myeloid cells showed reduced production of NO and IL-6 which was attributable to CD11b+ CD11c− Ly6C+ Ly6G− immature monocytic MDSC. TNFR2-deficient MDSC isolated from bone marrow were less suppressive for T cell proliferation compared to WT-derived MDSC. These differences on myeloid cells between the two mouse lines were still observed after co-culture of bone marrow cells from the two mouse lines together during myeloid cell differentiation, which demonstrated that the impaired functional capacity of TNFR2-deficient cells was independent of soluble factors but required membrane expression of TNFR2. Similarly, adoptive transfer of TNFR2-deficient bone marrow cells into wild-type hosts did not rescue the TNFR2-specific phenotype of bone marrow-derived myeloid cells. Therefore, membrane TNFR2 expression determines generation and function of monocytic MDSC.

Lack of functional selectin ligand interactions enhances inherent neutrophil function leading to increased resistance to systemic Listeria monocytogenes infection (INC7P.408)

Abstract Leukocyte recruitment towards sites of infection involves coordinated ligand-receptor interactions between leukocytes and the vascular wall. Selectins transiently bind to selectin ligands to enable leukocyte tethering and rolling on the vascular wall prior to leukocyte adhesion and transmigration into tissues. These interactions occur following post-translational modifications of selectin ligands, including terminal fucosylation by Fucosyltransferase-IV and -VII. In mice, deficiency in both enzymes (FtDKO) leads to loss of leukocyte tethering and rolling, increased circulating neutrophils and impaired T cell trafficking. However, the role of functional selectin ligand interactions in modulating immunity to bacterial infections remains unclear. We analyzed the kinetics of infection and modulation of immune responses in FtDKO mice infected with Listeria monocytogenes, an intracellular bacterium. FtDKO mice controlled systemic infection more rapidly relative to wild-type mice. This was correlated to increased number and functionality of neutrophils. Adoptive transfer of bone marrow cells from FtDKO mice into irradiated wild-type mice resulted in expansion of neutrophil populations and increased resistance to infection in a neutrophil-dependent manner. Functional selectin ligand deficiency on neutrophils was correlated to increased resistance to cell death. Thus, functional selectin ligand expression is a potential target for enhancing innate immunity against bacterial infection.

Abstract 18901: Metabolic Regulation of Adipose Tissue Inflammation and Systemic Insulin Sensitivity: A Role for PFKFB3 in Macrophage Polarization

Much evidence demonstrates that macrophages play a pivotal role in the development of overnutrition-associated metabolic diseases, such as cardiovascular disease and type II diabetes. Macrophage inflammatory status (polarization) is a key determinant of systemic insulin resistance, which is under the control of bi-directional regulation: macrophage proinflammatory activation and macrophage alternative activation (anti-inflammatory). It has been previously shown that PFKFB3, a gene that encodes for a key regulatory enzyme of glycolysis, is crucial for the control of systemic insulin sensitivity. In the present study, if and how PFKFB3 alters macrophage polarization in relation to adipose tissue inflammation and systemic insulin sensitivity were examined. Bone marrow cells were isolated from wild-type mice and PFKFB3-disrupted mice and differentiated into macrophages which were referred to as bone marrow-derived macrophages (BMDM). Compared with control cells, the phosphorylation of NF-kB p65 and JNK1/2 is in PFKFB3-disrupted BMDM. Additionally, the expression of proinflammatory cytokines, such as TNF-α and IL-6, was increased in PFKFB3-disrupted BMDM under the stimulation of lipopolysaccharides (LPS, 100 ng/ml). Upon adoptive transfer of bone marrow cells to lethally irradiated wild-type mice, the recipients with PFKFB3-disrupted bone marrow cells displayed a decrease in systemic insulin sensitivity, which was accompanied by an increase in adipose tissue inflammatory responses. The later were evidenced by increases in adipose tissue macrophage infiltration, the phosphorylation of NF-kB p65, and mRNA levels of proinflammatory cytokines. Taken together, PFKFB3 is a metabolic regulator of macrophage polarization, which accounts for the effects of PFKFB3 on protecting against diet-induced adipose tissue inflammation and systemic insulin resistance.

Internal carotid transfer of autologous bone-marrow mononuclear cells for the treatment of severe stroke in patient with thrombotic thrombocytopenic purpura

Internal carotid transfer of autologous bone-marrow mononuclear cells for the treatment of severe stroke in patient with thrombotic thrombocytopenic purpura

Distinct development and functions of resident and recruited liver Kupffer cells/macrophages

Although mouse liver F4/80(+) Kupffer cells consist of cytokine-producing CD11b(+) cells and phagocytic CD68(+) cells, an undefined CD11b(-) CD68(-) subset (30%) also exists. We herein demonstrate a more fundamental classification by adding CD32 (FcγRII), which covers most liver F4/80(+) cells and the distinct functions of them. Among the F4/80(+) cells, 50%, 40%, and 30% of cells were CD32(+), CD68(+), and CD11b(+), respectively, and one-half of the CD68(+) cells coexpressed CD32. CD68(+) and CD32(+) cells, but not CD11b(+) cells, expressed a phagocytosis-related CRIg. Gy (6) irradiation depleted liver CD11b(+) cells and those in the spleen, bone marrow, and peripheral blood but not liver CD32/CD68(+) cells. Transfer of bone marrow cells into the irradiated mice reconstituted liver CD11b(+) cells. Conversely, clodronate pretreatment depleted only liver CD32/CD68(+) cells but not liver CD11b(+) cells and peripheral blood or spleen CD11b(+) monocytes/macrophages. Moreover, the CD32(+) cells might be precursors of CD68(+) cells, as a large proportion of CD32(+) cells expressed the c-kit (CD117), and CD34 and CD32(+) cells acquired CD68 immediately after bacteria administration. CD32/CD68(+) cells, but not CD11b(+) cells, expressed resident macrophage-specific MerTK and CD64 (FcγRI). Challenge with Staphylococcus aureus or liver metastatic EL-4 tumor cells indicated that the CD68(+) subset is engaged in systemic bactericidal activity, whereas the CD11b(+) subset is pivotal for liver antitumor immunity. Human liver CD14(+) Kupffer cells could also be classified into three similar subsets. These results suggest that liver CD68(+) Kupffer cells and CD11b(+) Kupffer cells/macrophages are developmentally and functionally distinct subsets.

Recovery From Overt Type 1 Diabetes Ensues When Immune Tolerance and β-Cell Formation Are Coupled With Regeneration of Endothelial Cells in the Pancreatic Islets

Immune modulation of pancreatic inflammation induces recovery from type 1 diabetes (T1D), but remission was not durable, perhaps because of an inability to sustain the formation and function of new pancreatic β-cells. We have previously shown that Ig-GAD2, carrying GAD 206–220 peptide, induced in hyperglycemic mice immune modulation that was able to control pancreatic inflammation, stimulate β-cell regeneration, and prevent T1D progression. Herein, we show that the same Ig-GAD2 regimen given to mice with overt T1D was unable to reverse the course of disease despite eradication of Th1 and Th17 cells from the pancreas. However, the regimen was able to sustain recovery from T1D when Ig-GAD2 was accompanied with transfer of bone marrow (BM) cells from healthy donors. Interestingly, alongside immune modulation, there was concomitant formation of new β-cells and endothelial cells (ECs) in the pancreas. The new β-cells were of host origin while the donor BM cells gave rise to the ECs. Moreover, transfer of purified BM endothelial progenitors instead of whole BM cells sustained both β-cell and EC formation and reversal of diabetes. Thus, overcoming T1D requires both immune modulation and repair of the islet vascular niche to preserve newly formed β-cells.

Abstract 2871: Tumor-derived CCL2 promotes recruitment of CD11b/Gr1midmyeloid cells to sustain colorectal cancer liver metastasis.

Abstract Metastatic colorectal cancer (CRC) is one of the most prominent causes of cancer-related mortality. However, therapeutic options for patients with metastatic CRC are limited and development of new and more effective therapeutics aimed at downstaging the disease and prolonging survival is urgently required. Primary tumor dissemination to secondary sites, predominantly the liver, is a dynamic process dependent on the interactions between tumor cells and the host tissue microenvironment. Immune cells in the tumor microenvironment have been shown to play pivotal roles in the metastatic process but their pro-metastatic functions in CRC liver metastasis remains incompletely understood. To simulate liver metastasis, MC38 colon carcinoma cells were injected into the spleen of C57BL/6 mice. A population of CD11b/Gr1mid cells, distinct from other metastasis-associated myeloid cells previously described, increased dramatically during establishment of liver metastases. Adoptive transfer of bone marrow cells confirmed that these CD11b/Gr1mid cells were derived from bone marrow progenitor cells. MC38 tumor cells expressed high levels of CCL2 and serum levels were elevated in tumor-bearing mice compared to controls. Inhibition of tumor-derived CCL2 using shRNA, and absence of its cognate receptor in CCR2 KO mice significantly diminished CD11b/Gr1mid cell infiltration into tumor-bearing livers. Importantly, inhibition of CD11b/Gr1mid cell recruitment led to a marked reduction in tumor burden. Moreover, when CD11b/Gr1mid cells were depleted in a transgenic CD11b-DTR mouse model, a striking decrease in tumor vessel density was observed, with a concomitant reduction in tumor cell proliferation. Serum CCL2 concentrations were similarly elevated in CRC patients, including those who present metastasis, compared to normal controls. Furthermore, CD11b/CCR2 myeloid cells, analogous to the CD11b/Gr1mid population described in our mouse model, were identified in liver metastases of several CRC patients. Together, our studies demonstrate the importance of a distinct CD11b/Gr1mid myeloid subset in sustaining CRC liver metastasis and implicate a CCL2/CCR2-dependent pathway in their recruitment to metastatic sites. Our findings reinforce how tumor cells utilize host systems for successful propagation and identify a potential target for therapeutic manipulation. Citation Format: Su Yin Lim, Lei Zhao, Alex Gordon-Weeks, Thomas Tapmeier, Ruth Muschel. Tumor-derived CCL2 promotes recruitment of CD11b/Gr1mid myeloid cells to sustain colorectal cancer liver metastasis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2871. doi:10.1158/1538-7445.AM2013-2871

Toll-like receptor 3 plays a central role in cardiac dysfunction during polymicrobial sepsis*

To determine the role of Toll-like receptor 3 in cardiac dysfunction during polymicrobial sepsis. Controlled animal study. University research laboratory. Male C57BL/6, wild-type, Toll-like receptor 3-/-. Myocardial dysfunction is a major consequence of septic shock and contributes to the high mortality of sepsis. Toll-like receptors (TLRs) play a critical role in the pathophysiology of sepsis/septic shock. TLR3 is located in intracellular endosomes, and recognizes double-stranded RNA. This study examined the role of TLR3 in cardiac dysfunction following cecal ligation and puncture (CLP)-induced sepsis. TLR3 knockout (TLR3-/-, n=12) and age-matched wild-type (n=12) mice were subjected to CLP. Cardiac function was measured by echocardiography before and 6 hrs after CLP. CLP resulted in significant cardiac dysfunction as evidenced by decreased ejection fraction by 25.7% and fractional shortening by 29.8%, respectively. However, TLR3-/- mice showed a maintenance of cardiac function at pre-CLP levels. Wild-type mice showed 50% mortality at 58 hrs and 100% mortality at 154 hrs after CLP. In striking contrast, 70% of TLR3-/- mice survived indefinitely, that is, >200 hrs. TLR3 deficiency significantly decreased CLP-induced cardiac-myocyte apoptosis and attenuated CLP-induced Fas and Fas ligand expression in the myocardium. CLP-activation of TLR4-mediated nuclear factor-κB and Toll/IL-1 receptor-domain-containing adapter-inducing interferon-β-dependant interferon signaling pathways was prevented by TLR3 deficiency. In addition, CLP-increased vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 expression, and neutrophil and macrophage sequestration in the myocardium were also attenuated in septic TLR3-/- mice. More significantly, adoptive transfer of wild-type bone-marrow stromal cells to TLR3-/- mice abolished the cardioprotective effect in sepsis. These data indicate that TLR3 plays a deleterious role in mediating cardiac dysfunction in sepsis. Thus, modulation of the TLR3 activity may be useful in preventing cardiac dysfunction in sepsis.

Melanoma exosomes educate bone marrow progenitor cells toward a pro-metastatic phenotype through MET

Tumor-derived exosomes are emerging mediators of tumorigenesis. We explored the function of melanoma-derived exosomes in the formation of primary tumors and metastases in mice and human subjects. Exosomes from highly metastatic melanomas increased the metastatic behavior of primary tumors by permanently 'educating' bone marrow progenitors through the receptor tyrosine kinase MET. Melanoma-derived exosomes also induced vascular leakiness at pre-metastatic sites and reprogrammed bone marrow progenitors toward a pro-vasculogenic phenotype that was positive for c-Kit, the receptor tyrosine kinase Tie2 and Met. Reducing Met expression in exosomes diminished the pro-metastatic behavior of bone marrow cells. Notably, MET expression was elevated in circulating CD45(-)C-KIT(low/+)TIE2(+) bone marrow progenitors from individuals with metastatic melanoma. RAB1A, RAB5B, RAB7 and RAB27A, regulators of membrane trafficking and exosome formation, were highly expressed in melanoma cells. Rab27A RNA interference decreased exosome production, preventing bone marrow education and reducing, tumor growth and metastasis. In addition, we identified an exosome-specific melanoma signature with prognostic and therapeutic potential comprised of TYRP2, VLA-4, HSP70, an HSP90 isoform and the MET oncoprotein. Our data show that exosome production, transfer and education of bone marrow cells supports tumor growth and metastasis, has prognostic value and offers promise for new therapeutic directions in the metastatic process.

Nasopharyngeal colonization by Streptococcus pneumoniae elicits long-lasting immune responses that confer protection from invasive lung infections. (49.23)

Abstract Streptococcus pneumoniae can cause life-threatening pulmonary and systemic infection, but more commonly resides harmlessly in the nasopharynx. We demonstrated that nasopharyngeal (n.p.) colonization by S. pneumoniae in mice generates an antibody response that provides at least 10-week protection against lethal lung challenge. B cells were required for this protection, and transfer of sera from n.p.-colonized mice or antibodies against phosphorylcholine, a common S. pneumoniae surface antigen, protected naïve mice. Whereas T-independent anti-capsular antibodies were previously shown to be sufficient for protection against bloodstream infection , we found that T cells were required to generate a fully protective response following n.p. colonization. Depletion of CD4+ T cells at the time of pulmonary challenge or colonization of MHC class II-deficient mice did not compromise protection, suggesting a limited role for CD4+ T cells in our model. Sub-lethal irradiation of mice, which inactivates memory B cells but not long-lived plasma cells, did not significantly diminish protection, and transfer of bone marrow cells enriched for long-lived plasma cells from n.p.-colonized mice to B cell-deficient recipients increased pneumococcal-specific antibody titers and afforded significant protection. Our results suggest that n.p. colonization is capable of eliciting extended protection against invasive pneumococcal disease by generating long-lived antibody-secreting cells.

B cell development and immunoglobulin production are altered in the absence of IκBNS (109.4)

Abstract NF-κB transcription factors are key mediators of immune function as well as inflammatory responses. The activation of NF-κB is regulated by several IκB proteins, a family comprising classical cytoplasmic as well as nuclear IκBs. In this study, we focused on the role of IκBNS, a nuclear IκB protein, in B lymphocyte development and function. Analysis of lymphoid tissues from IκBNS knockout (KO) mice revealed that a lack of IκBNS affects the development of peritoneal B-1 cells and splenic marginal zone B cells. Development of B-2 cells was essentially normal. We also found that B cell proliferative activity and immunoglobulin production were altered in the absence of IκBNS. These defects were confirmed by the analysis of B cells in bone marrow chimeric mice constructed by the transfer of wild type or IκBNS KO bone marrow cells into B cell-deficient mice. Furthermore, histological analysis of spleens from chimeric mice revealed that re-constitution of B cell areas, marginal zones and germinal centers were markedly reduced in IκBNS KO cell recipient mice. Examination of the functions of IκBNS KO B cell subsets suggested that IκBNS is important for antibody production by both marginal zone and follicular B cells. These results indicate that IκBNS plays a key role in peripheral B cell development and function.

CARMA1 Controls Th2 Cell-Specific Cytokine Expression through Regulating JunB and GATA3 Transcription Factors

The scaffold protein CARMA1 is required for the TCR-induced lymphocyte activation. In this study, we show that CARMA1 also plays an essential role in T cell differentiation. We have found that the adoptive transfer of bone marrow cells expressing constitutively active CARMA1 results in lung inflammation, eosinophilia, and elevated levels of IL-4, IL-5, and IL-10 in recipient mice. In contrast, CARMA1-deficient T cells are defective in TCR-induced expression of Th2 cytokines, suggesting that CARMA1 preferentially directs Th2 differentiation. The impaired cytokine production is due to reduced expression of JunB and GATA3 transcription factors. CARMA1 deficiency affects JunB stability resulting in its enhanced ubiquitination and degradation. In contrast, TCR-dependent induction of GATA3 is suppressed at the transcriptional level. We also found that supplementation with IL-4 partially restored GATA3 expression in CARMA1-deficient CD4(+) splenocytes and subsequently production of GATA3-dependent cytokines IL-5 and IL-13. Therefore, our work provides the mechanism by which CARMA1 regulates Th2 cell differentiation.

Mice deficient in p52/NF-κB as a model for studying prion disease

AbstractA tight functional link between the central nervous and peripheral immune system closely related to the activity of NF-κB transcription factor has been evidenced in numerous brain pathological conditions. One of the most instructive examples is a prion neuroinvasion and the development of transmissible spongioform encephalopathy (TSE) or prion diseases. The failure of peripherally administrated prions to elicit disease in immune-deficient mice indicates that preserved organ microarchitecture is crucial for TSE pathogenesis and it seems to go through topographic relationships between follicular dendritic cells and sympathetic endings in lymphoid organs. New insight into the molecular requirements for follicular dendritic cell (FDC) development in NF-κB p52 deficient mice highlights the role of NF-κB transcription factor in prion disease progression. However, adoptive transfer of wild type bone marrow cells (NF-κB +/+ background) into p52 deficient animals (NF-κB -/- background) does not correct the FDC defect. RT-PCR analysis of the expression level of mRNA for LTa, LTb, TNFRI and BLC of the splenic cells from p52/NF-κB mutant/wt BM chimera did not reveal major changes compared to wt/wt BM chimeras, indicating that their normal expression within splenic tissue does not assure for complete restoration of the FDC network in p52/NF-κB mutant. This implies that the distance between FDCs and splenic nerve terminals around the central arteriole is longer and could interfere with prion spreading in lymphoid organs prior to neuroinvasion. In light of the fact that prion neuroinvasion highly depends on the physical distance between sympathetic nerve endings and FDCs dendritic extensions, it is not hard to imagine that this could be the way to approach the problem of prion diseases development.

Dual functions of cell-autonomous and non–cell-autonomous ADAM10 activity in granulopoiesis

AbstractPrevious studies have revealed various extrinsic stimuli and factors involved in the regulation of hematopoiesis. Among these, Notch-mediated signaling has been suggested to be critically involved in this process. Herein, we show that conditional inactivation of ADAM10, a membrane-bound protease with a crucial role in Notch signaling (S2 cleavage), results in myeloproliferative disorder (MPD) highlighted by severe splenomegaly and increased populations of myeloid cells and hematopoietic stem cells. Reciprocal transfer of bone marrow cells between wild-type and ADAM10 mutant mice revealed that ADAM10 activity in both hematopoietic and nonhematopoietic cells is involved in the development of MPD. Notably, we found that MPD caused by lack of ADAM10 in nonhematopoietic cells was mediated by G-CSF, whereas MPD caused by ADAM10-deficient hematopoietic cells was not. Taken together, the present findings reveal previously undescribed nonredundant roles of cell-autonomous and non–cell-autonomous ADAM10 activity in the maintenance of hematopoiesis.

Stem Cell Therapy for the Treatment of Myocardial Infarction

Despite timely reperfusion and subsequent optimal postinfarct pharmacotherapy and device-based treatment, the outcome in patients with severe myocardial infarction remains unfavourable. Myocardial salvage is incomplete, resulting in adverse left ventricular remodeling with concomitant morbidity and mortality. The combined risk of recurrent myocardial infarction, death or readmission for heart failure amounts to 25 % within the first year, highlighting the need for additional treatment strategies. Recent and rapidly evolving insights in cardiac biology, recognizing endogenous repair capabilities of the adult human heart, paved the path towards progenitor or stem cell based cardiac protection and repair strategies following ischemic injury. We critically report on the major randomized controlled clinical trials published so far concerning intracoronary transfer of autologous bone marrow cells in the setting of acute myocardial infarction. Moreover, underlying mechanisms, practical aspects, remaining questions and future challenges are highlighted. Taken together, these trials confirm the safety and feasibility of intracoronary progenitor cell transfer in the setting of myocardial infarction. Efficacy data suggests its potential to improve left ventricular function recovery beyond current state of the art therapy, but results are mixed, modest at best and do not support true cardiomyogenesis. Hence, due to its complexity, costs and remaining uncertainties, it is still too early to implement progenitor cell therapy in its current form in standard treatment strategies for ischemic heart disease. Future studies on strategies for cardiomyocyte regeneration in combination with myocardial protection are needed.