Vasoprotective effects of human CD34+ cells: towards clinical applications

Background

The development of cell-based therapeutics for humans requires preclinical testing in animal models. The use of autologous animal products fails to address the efficacy of similar products derived from humans. We used a novel immunodeficient rat carotid injury model in order to determine whether human cells could improve vascular remodelling following acute injury.

Methods

Human CD34+ cells were separated from peripheral buffy coats using automatic magnetic cell separation. Carotid arterial injury was performed in male Sprague-Dawley nude rats using a 2F Fogarty balloon catheter. Freshly harvested CD34+ cells or saline alone was administered locally for 20 minutes by endoluminal instillation. Structural and functional analysis of the arteries was performed 28 days later.

Results

Morphometric analysis demonstrated that human CD34+ cell delivery was associated with a significant reduction in intimal formation 4 weeks following balloon injury as compared with saline (I/M ratio 0.79 ± 0.18, and 1.71 ± 0.18 for CD34, and saline-treated vessels, respectively P < 0.05). Vasoreactivity studies showed that maximal relaxation of vessel rings from human CD34+ treated animals was significantly enhanced compared with saline-treated counterparts (74.1 ± 10.2, and 36.8 ± 12.1% relaxation for CD34+ cells and saline, respectively, P < 0.05)

Conclusion

Delivery of human CD34+ cells limits neointima formation and improves arterial reactivity after vascular injury. These studies advance the concept of cell delivery to effect vascular remodeling toward a potential human cellular product.

Tumor-associated macrophages infiltrate plasmacytomas and can serve as cell carriers for oncolytic measles virotherapy of disseminated myeloma

In multiple myeloma, some of the neoplastic plasma cells are diffusely dispersed among the normal bone marrow cells (bone marrow resident), whereas others are located in discrete, well-vascularized solid tumors (plasmacytomas) that may originate in bone or soft tissue. Interactions between bone marrow-resident myeloma cells and bone marrow stromal cells (BMSCs) are important determinants of myeloma pathogenesis. However, little is known of the factors sustaining myeloma growth and cell viability at the centers of expanding plasmacytomas, where there are no BMSCs. Histologic sections of 22 plasmacytomas from myeloma patients were examined after immunostaining. Abundant CD68+, CD163+, S100-negative macrophage infiltrates were identified in all tumors, accompanied by scattered collections of CD3+ T lymphocytes. The CD68+ tumor-associated macrophages (TAM) accounted for 2-12% of nucleated cells and were evenly distributed through the parenchyma. The TAM generally had dendritic morphology, and each dendrite was in close contact with multiple plasma cells. In some cases, the TAM were strikingly clustered around CD34+ blood vessels. To determine whether cells of the monocytic lineage might be exploitable as carriers for delivery of therapeutic agents to plasmacytomas, primary human CD14+ cells were infected with oncolytic measles virus and administered intravenously to mice bearing KAS6/1 human myeloma xenografts. The cell carriers localized to KAS6/1 tumors, where they transferred MV infection to myeloma cells and prolonged the survival of mice bearing disseminated human myeloma disease. Thus, TAM are a universal stromal component of the plasmacytomas of myeloma patients and may offer a promising new target for therapeutic exploitation. Am. J. Hematol. 2009. (c) 2009 Wiley-Liss, Inc.

Carotid repair using autologous adipose-derived endothelial cells

BACKGROUND AND PURPOSE

Adipose tissue is an abundant source of endothelial cells as well as stem and progenitor cells which can develop an endothelial phenotype. It has been demonstrated that these cells have distinct angiogenic properties in vitro and in vivo. However, whether these cells have the capacity to directly improve large vessel form and function after vascular injury remains unknown. To define whether delivery of adipose-derived endothelial cells (ADECs) would improve healing of injured carotid arteries, a rabbit model of acute arterial injury was used.

METHODS

Autologous rabbit ADECs were generated using defined culture conditions. To test the ability of ADECs to enhance carotid artery repair, cells were delivered intraarterially after acute balloon injury. Additional delivery studies were performed after functional selection of cells before delivery.

RESULTS

After rabbit omental fat harvest and digestion, a proliferative, homogenous, and distinctly endothelial population of ADECs was identified. Direct delivery of autologous ADECs resulted in marked reendothelialization 48 hours after acute vascular injury as compared to saline controls (82.2+/-26.9% versus 4.2+/-3.0% P<0.001). Delivery of ADECs that were selected for their ability to take up acetylated LDL significantly improved vasoreactivity and decreased intimal formation after vascular injury.

CONCLUSIONS

Taken together, these data suggest that ADECs represent an autologous source of proliferative endothelial cells, which demonstrate the capacity to rapidly improve reendothelialization, improve vascular reactivity, and decrease intimal formation in a carotid artery injury model.

Infrastructure Development for Human Cell Therapy Translation

The common conception of a drug is that of a chemical with defined medicinal effect. However, cells used as drugs remain critical to patient care. Cell therapy's origins began with the realization that complex tissues such as blood can retain function when transplanted to the patient. More complex transplantation followed, culminating with the understanding that transplantation of some tissues such as bone marrow may act medicinally. Administration of cells with an intended therapeutic effect is a hallmark of cellular therapy. While cells have been used as drugs for decades, testing a specific therapeutic effect of cells has begun clinical testing relatively recently. Lessons learned during the establishment of blood banking (including the importance of quality control, process control, sterility, and product tracking) are key components in the assurance of the safety and potency of cell therapy preparations. As more academic medical centers and private companies move toward exploiting the full potential of cells as drugs, needs arise for the development of the infrastructure necessary to support these investigations. Careful consideration of the design of the structure used to manufacture is important in terms of the significant capital outlay involved and the facility's role in achieving regulatory compliance. This development perspective describes the regulatory environment surrounding the infrastructure support for cell therapy and practical aspects for design consideration with particular focus on those activities associated with early clinical trials.

Plasmacytoid dendritic cells in inflamed muscle of patients with juvenile dermatomyositis

OBJECTIVE

To examine whether dendritic cells (DCs) are constituents of muscle inflammation in juvenile dermatomyositis (DM).

METHODS

The types, numbers, and activation state of DC subsets in inflamed muscle tissue from patients with juvenile DM and in noninflamed muscle tissue from control subjects were examined by multicolor immunofluorescence. Chemokine expression of the muscle-infiltrating cells was examined by laser capture microdissection and quantitative polymerase chain reaction.

RESULTS

Plasmacytoid DCs were the predominant component of the inflamed muscle tissue from patients with juvenile DM. These cells were identified by coexpression of CD4 and CD123, but not CD11c, and also expressed CD83, indicating maturity of the cells. In contrast, in noninflamed muscle, plasmacytoid DCs were scarce and did not express CD83. Mononuclear cells surrounding the blood vessels of inflamed muscle contained abundant transcripts of CCL19 and CCL21, but very little CCL18 transcripts. In contrast, cells from noninflamed muscle contained negligible amounts of CCL19 and CCL21, but had high amounts of CCL18. Both the inflamed and noninflamed muscle tissue had equivalent levels of CXCL12 transcripts, but inflamed muscle contained more transcripts of the CXCL12 receptor CXCR4.

CONCLUSION

These findings are consistent with the idea that plasmacytoid DCs are mediators of muscle inflammation in juvenile DM. The abundance of CD83+ plasmacytoid DCs in perivascular areas and the overexpression of CCL19 and CCL21 in perivascular cellular foci suggest that in situ activation and maturation of resident plasmacytoid DCs are central to the initiation and perpetuation of muscle inflammation in juvenile DM.

Sterility testing of hematopoietic progenitor cell products: a single-institution series of culture-positive rates and successful infusion of culture-positive products

BACKGROUND

Administration of culture-positive hematopoietic progenitor cells (HPCs) causing adverse events has been a hypothesized yet largely unmeasured risk of the clinical practice of HPC transplantation. To enhance patient safety, the FDA has issued regulations prohibiting the use of culture-positive HPCs. Numerous studies have reported the infusion of culture-positive HPCs; however, the low frequency of adverse events prevents accurate determination of this risk.

STUDY DESIGN AND METHODS

Product culture results and clinical outcomes from January 1998 through March 2006 representing 7233 HPC collections for 2118 transplants at a single institution were reviewed.

RESULTS

A total of 119 units of HPCs (1.6%) intended for 95 patients were culture-positive. Of the 69 patients transplanted with culture-positive HPCs, 5 received products with cultures pending, and 64 received products with the positive culture results known. One of 69 patients had a new positive blood culture 5 days after infusion with the same species as the product. There was not a clinically relevant difference in the rate of infusion-related symptoms reported for patients who received culture-positive products compared to all infusions. The survival of patients who received culture-positive products (n = 69) was not different from all HPC recipients (n = 2046; p = 0.419).

CONCLUSION

No infusion-related risks of culture-positive HPCs to patient safety were identified. Our data suggest that the decision to use culture-positive HPCs must be made in the context of the global risks associated with transplants such as remobilization, replacement product availability, and the nature of the organism.

A novel source of viable peripheral blood mononuclear cells from leukoreduction system chambers

BACKGROUND

Buffy coats are becoming less available as a source of research-grade peripheral blood mononuclear cells (PBMNCs). Therefore, alternative sources of these cells were investigated.

STUDY DESIGN AND METHODS

PBMNCs isolated from the cells retained in leukoreduction system chambers (LRSCs) and those eluted from white blood cell filters were compared. From LRSCs (1.88 +/- 0.40) x 10(9) PBMNCs (n = 13) versus (0.43 +/- 0.15) x 10(9) PBMNCs were isolated from leukofilter eluates (LFEs, n = 8; p < 0.0001).

RESULTS

Cells from LRSCs and LFEs produced similar numbers of burst-forming unit-erythroid, colony-forming unit (CFU)-granulocyte-macrophage, and CFU-granulocyte-erythrocyte-monocyte-macrophage-megakaryocyte colonies. The percentages of cells positive for CD3, CD4, CD8, CD14, CD19, and CD56 in the PBMNCs isolated from LRSCs and LFEs were indistinguishable. Cells isolated from LRSCs expressed higher levels of CD69 and CD25 in reaction to staphylococcal enterotoxin B than the cells isolated from LFEs. The source of cells affected neither the yield and purity of immunomagnetically isolated CD3+ cells, CD14+ cells, and CD56+ cells nor the function of T cells, natural killer cells, and in vitro matured dendritic cells (DCs). DC yield from LRSC-derived CD14+ cells, however, was higher.

CONCLUSION

LRSCs are a novel source of fully functional PBMNCs that can replace the more traditional sources of research-grade cellular products.

Evaluation of T cells as carriers for systemic measles virotherapy in the presence of antiviral antibodies

Neutralizing antiviral antibodies (Abs) can hinder systemic virotherapy. Here, we used activated T cells as carriers to deliver oncolytic measles viruses (MV) to multiple myeloma xenografts in the presence of anti-MV antibodies (Abs). Virus-infected T cells expressing measles H/F fusogenic envelope glycoproteins could efficiently transfer MV infection by heterofusion, even after exposure to virus-inactivating anti-MV antisera. Severe-combined immunodeficiency (SCID) mice bearing subcutaneous or disseminated human myeloma xenografts were given MV-luciferase (MV-Luc) or MV-Luc-infected T cells intravenously. Indium111 labeling indicated that 1-2% of the virus-infected T cells trafficked to tumors. Preinfected T cells fused with tumor cells in vivo and transferred MV-Luc to tumor xenografts where intratumoral viral spread was monitored non-invasively using bioluminescent imaging. In mice passively immunized with high titers of measles immune serum, intravenous virus and cell delivery were both inhibited. Decreasing the amount of measles immune serum given to mice permitted tumor infection by virus-infected T cells and cell-free virus. In conclusion, virus-loaded T cells may facilitate systemic measles virotherapy in the presence of antiviral Abs and they warrant further investigation as potential MV cell carriers.

Preparing clinical-grade myeloid dendritic cells by electroporation-mediated transfection of in vitro amplified tumor-derived mRNA and safety testing in stage IV malignant melanoma

BACKGROUND

Dendritic cells (DCs) have been used as vaccines in clinical trials of immunotherapy of cancer and other diseases. Nonetheless, progress towards the use of DCs in the clinic has been slow due in part to the absence of standard methods for DC preparation and exposure to disease-associated antigens. Because different ex vivo exposure methods can affect DC phenotype and function differently, we studied whether electroporation-mediated transfection (electrotransfection) of myeloid DCs with in vitro expanded RNA isolated from tumor tissue might be feasible as a standard physical method in the preparation of clinical-grade DC vaccines.

METHODS

We prepared immature DCs (IDCs) from CD14+ cells isolated from leukapheresis products and extracted total RNA from freshly resected melanoma tissue. We reversely transcribed the RNA while attaching a T7 promoter to the products that we subsequently amplified by PCR. We transcribed the amplified cDNA in vitro and introduced the expanded RNA into IDCs by electroporation followed by DC maturation and cryopreservation. Isolated and expanded mRNA was analyzed for the presence of melanoma-associated tumor antigens gp100, tyrosinase or MART1. To test product safety, we injected five million DCs subcutaneously at three-week intervals for up to four injections into six patients suffering from stage IV malignant melanoma.

RESULTS

Three preparations contained all three transcripts, one isolate contained tyrosinase and gp100 and one contained none. Electrotransfection of DCs did not affect viability and phenotype of fresh mature DCs. However, post-thaw viability was lower (69 +/- 12 percent) in comparison to non-electroporated cells (82 +/- 12 percent; p = 0.001). No patient exhibited grade 3 or 4 toxicity upon DC injections.

CONCLUSION

Standardized preparation of viable clinical-grade DCs transfected with tumor-derived and in vitro amplified mRNA is feasible and their administration is safe.

Testing the safety of clinical-grade mature autologous myeloid DC in a phase I clinical immunotherapy trial of CML

BACKGROUND

We conducted a phase I clinical immunotherapy trial of CML to evaluate the safety of a clinical-grade leukemic DC product standardized for purity and mature phenotype.

METHODS

We injected autologous DC into patients in late chronic or accelerated phases of CML. The patients received mature CD83+ and bcr-abl+ DC prepared from CD14+ cells. Two cohorts of three patients received four injections each of 3 x 10(6) DC and 15 x 10(6) DC/injection, respectively. The first patient was studied before imatinib mesylate (IM) was available, four patients were treated concurrently with IM therapy and one did not tolerate the IM and was off the drug at the time of DC therapy. IM effects on WBC counts precluded DC preparation in numbers sufficient for further dose escalation. The first patient received DC s.c. and all subsequent patients received DC into a cervical lymph node under ultrasound guidance.

RESULTS

DC injections were well tolerated. We observed no clinical responses. T cells drawn later in the course of therapy were more sensitive to stimulation by CML DC in vitro.

DISCUSSION

The increase in T-cell sensitivity to CML-specific stimulation that accompanied active immunization by CML DC justifies further clinical studies, possibly with modifications such as an increased frequency and number of DC injections.

Clinical-grade manufacturing of DC from CD14+ precursors: experience from phase I clinical trials in CML and malignant melanoma

BACKGROUND

We evaluated a clinical-grade protocol for the manufacture of mature DC from CD14 + precursors derived from normal donors and patients suffering from CML and stage IV malignant melanoma. We manufactured six products for CML patients and five for melanoma patients and administered them as vaccines in phase I clinical trials.

METHODS

We isolated CD 14+ cells from apheresis products by immunomagnetic separation and incubated them in X-VIVO 15' medium supplemented with human AB serum, GM-CSF and IL-4 for 7 days, and with additional tumor necrosis factor (TNF)-a, IL-lIf, IL-6 and prostaglandin E2 for 3 days. Some cells were electroporated and transfected with mRNA isolated from melanoma tissue. DC were characterized by flow cytometry for the expression of CD83, CD86 andCD14.

RESULTS

CD14+ cells constituted 14.4+/-6.2% (mean + SD) of nucleated cells in apheresis products and 98.3+/- 3.6% of isolated cells. Normal DC and CML DC were 77.4+/-7.3% CD83+ and 93.5+/- 7.0% CD86+. Corresponding values for electroporated DC from melanoma patients were 66.1 + 7.2% and 94.1 + 7.8%. The yield of CD83+ DC from isolated CD14+ cells was 18.1 + 7.2% for normal and CML patients and 9.8 + 3.7% for melanoma patients. DC viability was 92.7 + 5.8%; after cryopreservation and thawing it was 77+/-13.5%.

DISCUSSION

Our method yielded viable and mature DC free of bacteria and mycoplasma. This robust and reproducible method provides cells of consistent phenotype and viability. Cryopreservation in single-dose aliquots allows multiple DC vaccine doses to be manufactured from a single apheresis product.

Imatinib mesylate inhibits T-cell proliferation in vitro and delayed-type hypersensitivity in vivo

Imatinib mesylate (STI571, imatinib) inhibited DNA synthesis in primary human T cells stimulated with allogeneic mature dendritic cells or phytohemagglutinin (PHA) but did not induce apoptosis. The values for the concentration that inhibits 50% (IC50) of T-cell proliferation stimulated by dendritic cells and PHA were 3.9 μM and 2.9 μM, respectively, that is, within the concentration range found in patients treated with imatinib mesylate. Interestingly, imatinib mesylate did not inhibit expression of T-cell activation markers CD25 and CD69, although it reduced the levels of activated nuclear factor-κB (NF-κB) and changed phosphorylation or protein levels of Lck, ERK1/2, retinoblastoma protein, and cyclin D3. When T cells were washed free of imatinib mesylate, they proliferated in response to PHA, demonstrating that inhibition is reversible. Treatment with imatinib mesylate led to accumulation of the cells in G0/G1 phase of the cell cycle. The in vitro observations were confirmed in vivo in a murine model of delayed-type hypersensitivity (DTH). In mice treated with imatinib mesylate, DTH was reduced in comparison to sham-injected controls. However, the number of splenic T cells was not reduced showing that, similarly to in vitro observations, imatinib mesylate inhibited T-cell response, but did not cause apoptosis. These findings indicate that long-term administration of high-dose imatinib mesylate might affect immunity.

Cloning the cDNA for murine U2 snRNP-A' gene and its differential expression in lymphocyte development

We studied genes differentially transcribed during development of murine thymocytes. By the use of differential display of mRNA by polymerase chain reaction (DD-PCR) we identified a cDNA for U2snRNP-A' from a transcript abundant in precursor thymocytes, but rare in mature T cells. The transcript was fully cloned and found to be 97% homologous to the human cDNA for U2 snRNP-A'. We found the gene most abundantly transcribed on day 15 of gestation and in adult prothymocytes, spleen, testis and liver. Further characterization of snRNP proteins in the mouse is warranted in an effort to establish animal models of autoimmunity relevant for studies of connective tissue diseases or systemic lupus erythematosus, where patients harbor autoantibodies reactive to snRNP.

Transgenic interleukin 2 secreted by CML dendritic cells stimulates autologous T(H)1 T cells

BACKGROUND

We investigated if dendritic cells (DC), derived from patients suffering from chronic myeloid leukemia (CML) could be modified by recombinant replication-defective adenoviruses to express functional interleukin 2 (IL-2). Such modification might confer onto antigen-presenting cells the ability to stimulate expansion of effector cells.

METHODS

To quantify the infection efficiency of CML dendritic cells (CML-DC) by recombinant adenovirus, we measured the expression of green fluorescent protein (GFP) gene contained in the virus. In CML-DC infected with an adenovirus containing the IL-2 gene, we evaluated their ability to secrete IL-2 and stimulate proliferation of autologous T cells.

RESULTS

Uninfected CML-DC and normal DC secreted similar amounts of IL-12 and stimulated similarly efficient autologous mixed leukocyte reaction. Immature CML-DC infected by an adenovirus containing the gene for IL-2 secreted large amounts of IL-2 and stimulated proliferation of autologous T cells more efficiently than the corresponding CML-DC alone. High levels of interferon eta, but not of IL-4, in cell culture supernates indicated that the proliferating cells were T(H)1. Infected mature CML-DC were more effective than infected immature CML-DC, showing that T cell stimulation by mature DC and by IL-2 was additive.

DISCUSSION

CML-DC can be modified genetically and functionally by recombinant replication-defective adenoviruses, providing new possibilities for clinical trials in dendritic cell-based immunotherapy.

Immunomagnetic separation reagents as markers in electron microscopy

Antibodies coupled to magnetic particles have been employed for immunomagnetic cell isolation, but their consequent use for electron microscopy (EM) has not been evaluated. We used commercial antibodies coupled to iron-dextran to isolate T cells and monocytes/macrophages by immunomagnetic adsorption from normal human peripheral blood mononuclear cells. Subsequently, we studied the association of electron-dense immunomagnetic reagents with cell membranes. CD14-positive monocytes/macrophages isolated from fixed peripheral blood mononuclear cells retained electron-dense beads on the plasma membrane, while live cells internalized them. Flow cytometry and electron microscopy measurements of the percentage of cells that bound a CD4-specific immunomagnetic reagent in pan-T cell isolates (containing numerous T cell subtypes) were indistinguishable. The immunomagnetic reagent associated with cells could be secondarily labeled by secondary antibody coupled to colloidal gold. This study shows that these reagents used for cell isolation or just labeling, remain associated with their targets at the cell membrane. Immunomagnetic reagents allow "capturing" of rare cells from complex mixtures, purifying and concentrating them in a single step for subsequent electron microscopy. The large number of commercially available immunomagnetic reagents specific for different human, mouse and rat antigens provides additional resources for visualization of cellular ultrastructure.

In vivo sodium iodide symporter gene therapy of prostate cancer

Radioiodine therapy, the most effective form of systemic radiotherapy available, is currently useful only for thyroid cancer because of thyroid-specific expression of the sodium iodide symporter (NIS). Here we explore the efficacy of a novel form of gene therapy using adenovirus-mediated in vivo NIS gene transfer followed by (131)I administration for treatment of prostate cancer. Prostate cancer xenografts in nude mice injected with an adenovirus carrying the NIS gene linked to the cytomegalovirus (CMV) promoter revealed highly active uptake of radioiodine. Following administration of 3 mCi of (131)I, we observed an average tumor volume reduction of 84 +/- 12%. These results show for the first time that in vivo NIS gene delivery into non-thyroidal tumors is capable of inducing accumulation of therapeutically effective radioiodine doses and might therefore represent an effective and potentially curative therapy for prostate cancer.

Maturation of human dendritic cells as sulfasalazine target

AIM

Sulfasalazine, a nonsteroidal anti-inflammatory drug, is effective in treating some autoimmune diseases, but its mechanism of action is unclear. To determine whether dendritic cells could be a possible target of the drug, we studied the effects of sulfasalazine and its metabolites, aminosalicylate and sulfapyridine, on in vitro maturation (terminal differentiation) of human myeloid dendritic cells.

METHODS

We prepared immature dendritic cells by incubating CD14-positive cells in the presence of granulocyte- macrophage colony-stimulating factor and interleukin (IL)-4. The cells were matured by addition of tumor necrosis factor (TNF)-a, IL-1 beta, and prostaglandin E2 in the presence of sulfasalazine or its metabolites -- aminosalicylate and sulfapyridine, or their combinations. We quantified the effect of drugs on the dendritic cell characteristics, such as stimulation of autologous and allogeneic pan-T cell proliferation, surface marker phenotype, IL-12 p40 subunit secretion, and activation of nuclear transcription factor (NF)-kappa B.

RESULTS

Dendritic cells treated with sulfasalazine (1.25 micromol/L or 2.5 micromol/L) could not stimulate T cells (p<0.028, two-sided paired t-test). In distinction to drug-free maturing dendritic cells, 2.5 micromol/L sulfasalazine upregulated the levels of CD14 and CD68 and downregulated the levels of CD40, CD80, and CD83 (for all CD markers, p<0.03 for difference between measurements in the absence and the presence of sulfasalazine). From concentration-dependent changes in CD83 expression, we found an apparent ID50 >>1.5 micromol/L sulfasalazine. The apparent ID50 value for aminosalicylate-inhibited maturation was 4 micromol/L. Sulfapyridine had no effect. At 1.25 micromol/L, sulfasalazine largely inhibited NF-kB activation in dendritic cells.

CONCLUSION

Maturing human dendritic cells are hundred-fold more sensitive to sulfasalazine than T cells and NK cells and the most sensitive human cells described so far. Thus, dendritic cell maturation is an important target of sulfasalazine. Because of the role of dendritic cells in (auto)immunity, inhibition of their maturation might provide a target for further optimization of sulfasalazine therapy.

Engineering dendritic cell grafts for clinical trials in cellular immunotherapy of cancer: example of chronic myelogenous leukemia

Dendritic cells are pivotal regulators of immune reactivity and immune tolerance. The observation that dendritic cells can recruit naive T-cells has invigorated cancer immunology and stimulated clinical trials of dendritic cells in immunotherapy. However, variables inherent in preparation and use of dendritic cell grafts remain to be tested. Here we discuss the role of ex vivo dendritic cell processing for in vivo antigen presentation in clinical trials. As an example of the complexity in a clinical trial of dendritic cell vaccines, we present our ongoing trial in immunotherapy of chronic myelogenous leukemia.

Maturation of dendritic cells infected by recombinant adenovirus can be delayed without impact on transgene expression

Adenovirus-mediated gene transfer to dendritic cells is highly efficient and often used, but the relationship among cell maturation, viral infection and expression of a transferred gene remains unclear. To study this relationship, we introduced a recombinant replication-defective adenovirus encoding the gene for green fluorescent protein to normal human immature myeloid dendritic cells. We induced maturation by the addition of TNF-alpha, IL-1beta, IL-6 and prostaglandin E2 to the medium and assessed cell maturity by the levels of the secreted p40 subunit of IL-12 and of membrane-bound CD83. We quantified the efficiency of gene expression by GFP fluorescence and analyzed the data by a mixed-model analysis of variance; the model explained more than 97% of the effects. CD83 expression and p40 secretion depended solely on incubation time and maturation medium. The cells cultured in the absence of maturation medium remained immature and maintained the ability to respond to the later addition of the maturation irrespective of adenovirus infection and transferred gene expression. This expression was independent of cell maturation. In comparison with mature cells, the transferred gene was expressed in immature dendritic cells with a lag compatible with the less effective initial step (infection and/or gene transfer) in the absence of the maturation medium rather than less effective later GFP synthesis. Expression of CD83 and p40 were unaffected by adenovirus infection and transferred gene expression. Thus, immature dendritic cells infected with recombinant adenoviruses can be matured when desired after transferred gene expression.

Maturation of human monocyte-derived dendritic cells studied by microarray hybridization

We compared the transcript profiles of human myeloid immature dendritic (IDC) cells and mature dendritic cells (MDC) by hybridization of cell-derived cDNA to DNA probes immobilized on microarrays. The microarrays contained probes for 4110 known genes. We report maturation-dependent changes in transcription of clusters of differentiation, cytokines, cytokine receptors, chemokines, chemokine receptors, neuropeptides, adhesion molecules, and other genes. We identified 1124 transcripts expressed in IDC and 1556 transcripts expressed in MDC. Maturation increased the levels of 291 transcripts twofold or more and reduced the levels of 78 transcripts to one-half or less than in IDC. We identified a concerted maturation-stage-dependent transcription of the variable chains of the members of the gamma-chain-cytokine receptor family IL-4R, IL-7R, and IL-15R. Also, we found the reversal of the ratio of transcripts for galectin-3 and galectin-9 upon maturation. We identified maturation-dependent changes in the levels of transcripts for numerous genes encoding proteins previously undetected in dendritic cells such as indoleamine 2,3-deoxygenase, Epstein-Barr virus induced protein 3 and kinesin-2. Moreover, MDC transcribed and translated insulin like growth factor-1 receptor, transforming growth factor alpha, and neuropeptide Y.

Cyclooxygenase-independent inhibition of dendritic cell maturation by aspirin

When immature human myeloid dendritic cells were differentiated in vitro in the presence of aspirin, they were unable to stimulate T-cell proliferation. Aspirin and its major metabolite salicylate changed the surface marker phenotype of dendritic cells. The drugs particularly suppressed the levels of CD83 and the secreted p40 unit of interleukin-12 (IL-12), both markers of mature dendritic cells; 50% inhibitory concentration (IC50) values were 2.5 mM, a concentration more than 100 times greater than the concentration at mid-point inhibition (ID50) value for inhibition of prostaglandin synthesis. Concomitantly, the levels of CD14, a marker of monocytes/macrophages, increased above the levels found in immature dendritic cells. Cyclooxygenase inhibitors ketoprofen, indomethacin and NS-398 had no effect at concentrations more than a thousand-fold higher than their IC50 values. The effects were independent of the presence of prostaglandin E2 in the medium. Salicylates suppressed activation of the nuclear transcription factor kappaB, which regulates dendritic cell differentiation, but their effects on mature dendritic cells were negligible. Hence, aspirin inhibits dendritic cell function by inhibiting their terminal differentiation at concentrations achieved in the blood of patients chronically treated with high-dose aspirin.

Optimizing preparation of normal dendritic cells and bcr-abl+ mature dendritic cells derived from immunomagnetically purified CD14+ cells

The goal of this work was to optimize dendritic cell (DC) preparations obtained from patients suffering from chronic myeloid leukemia (CML) and compare them with DC prepared from normal CD14+ mononuclear cells (MNC). We studied normal DC and bcr-abl+ leukemic DC (CML-DC) yields, expression of membrane molecules, differentiation status, and ability to stimulate T cells. We isolated DC precursors from PBMC by CD14-specific immunoadsorption and cultured them for 7 days in GM-CSF and IL-4, followed by a 3-day incubation to fully differentiate the cells. We evaluated cultures of CML-DC using RPMI 1640 medium supplemented with FBS and X-VIVO 15 medium containing human AB serum. In contrast to cells matured in RPMI 1640, virtually all cells incubated in X-VIVO 15 expressed CD83, a marker of mature DC. CML-DC and normal DC were indistinguishable in expression of CD83, resulting in the highest percentage reported so far. The yields of normal DC and CML-DC from CD14+ cells were indistinguishable. The percentage of bcr-abl+ cells in PBMC varied among patients between 65% and 97% and the final CML-DC preparations were >98% bcr-abl+ the highest purity of bcr-abl+ cells to date. Normal DC and CML-DC were equally effective in stimulating proliferation of allogeneic and autologous T cells. These techniques provide highly enriched, mature, functional CML-DC.

Dexamethasone inhibits dendritic cell maturation by redirecting differentiation of a subset of cells

To investigate how corticosteroids affect differentiation of human dendritic cells (DC) in a defined inflammatory environment, we incubated immature DC with dexamethasone in the presence of tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), and prostaglandin E2. Dexamethasone inhibited differentiation into mature DC, as indicated by the reduced expression of antigen-presenting molecules, costimulatory and adhesion molecules, a marker of mature DC, and IL-12. Dexamethasone increased expression of CD14, CD36, and CD68, molecules characteristic of monocytes/macrophages and induced CD14+CD83- cells, a subset distinct both from immature DC and mature DC. The effects were concentration-dependent, with ID50 values between 2 and 30 nM dexamethasone. Unlike T and B cells, in DC dexamethasone induced no apoptosis, although it suppressed activated nuclear transcription factor NF-kappaB. Dexamethasone reduced the ability of DC to stimulate proliferation of allogeneic T cells in proportion to the level of CD14+CD83- cells in the population. CD83+ cells, isolated from dexamethasone-treated populations, retained the synthesis of IL-12 and the ability to stimulate proliferation of allogeneic T cells. Our data demonstrate that the dominant effect of the drug was redirecting differentiation of a subset of cells despite the presence of inflammatory cytokines. The observed ID50 values indicate that inhibition of DC differentiation might contribute significantly to in vivo immunosuppression by chronic administration of corticosteroids.

Production and characterization of canine osteosarcoma cell lines that induce transplantable tumors in nude mice

OBJECTIVE

To produce and characterize cell lines from canine primary appendicular osteosarcomas that induce transplantable tumors in athymic nude mice.

ANIMALS

57 six- to 8-week-old female athymic nude mice.

PROCEDURE

Canine primary appendicular osteosarcoma tumors were harvested and cell lines were produced. Canine osteosarcoma (COSCA)-Toby (COSCA-T; 10 mice), COSCA-Princess (COSCA-Pr; 16) or canine osteosarcoma D-17 (ATCC CCL-183; 31) cells were injected into the proximal portion of the left tibia of nude mice to evaluate tumor production from each cell line; the right tibia served as the control. Tibial measurements were taken on alternating days to evaluate tumor growth during a 6-month period. Student's t-tests were used to determine whether size of the proximal portion of the left and right tibias differed significantly during the observation period.

RESULTS

88% of mice receiving COSCA-Pr and 50% of mice receiving COSCA-T cells developed a tumor at the injection site by 9 days after implantation. The D-17 cells induced tumors in 50% of injected tibias; however, tumors were not detected for 79 days. Tumors generated from COSCA-Pr and COSCA-T cells in nude mice were histologically similar to the canine tumor from which they were developed.

CONCLUSION

New osteosarcoma cell lines that can reliably and rapidly induce transplantable tumors in nude mice were developed.

CLINICAL RELEVANCE

Use of cell lines will allow evaluation of new treatments of canine primary appendicular osteosarcoma in a nude mouse model.

High efficiency adenovirus-mediated gene transfer to human dendritic cells

The interest in the use of human dendritic cells in cancer immunotherapy calls for efficient ex vivo methods of dendritic cell education. To extend the range of methods available, we generated phenotypically characteristic dendritic cells from peripheral blood monocytes incubated with granulocyte-macrophage colony-stimulating factor and interleukin-4 and infected them with an adenovirus containing a humanized version of green fluorescent protein as a marker of gene expression. The levels of expressed protein were high, but they were further increased in combination with cationic liposomes. In comparison to transfection efficiency of the homologous expression plasmid, adenovirus-mediated gene transfer was substantially more efficient. With the aid of liposome-mediated infection, gene transfer into CD83+ dendritic cells was highly effective, resulting in more than 90% of the cells expressing the transgene.

Genetic association between parameters of inmate immunity and measures of mastitis in periparturient Holstein cattle

Relationships between genetic measures of mastitis (somatic cell score, score for clinical mastitis, and scores for IMI with major or minor pathogens) and immunological parameters (physiological and molecular markers) were examined for periparturient Holstein cows. Physiological markers included 11 in vitro immunological assays. Molecular markers included the second exon of the DRB3 locus of the bovine major histocompatibility complex, the IgG2 isotype genotype, and the CD18 genotype (the locus responsible for bovine leukocyte adhesion deficiency). A gene substitution model was used to estimate the additive genetic effects of alleles of the three molecular markers on estimated breeding value (EBV) for mastitis measures. Pearson correlation coefficients between EBV for immunological assays and EBV for mastitis measures were computed. Molecular markers explained up to 40% of the variation in EBV for measures of mastitis. The presence of allele DRB3.2*16 was associated with higher EBV for SCS. Allele DRB3.2*8 was associated with increased EBV for clinical mastitis, as was the IgG2b allele and the normal CD18 allele. Alleles DRB3.2*11, *23, IgG2a, and the recessive allele for bovine leukocyte adhesion deficiency were associated with decreased clinical mastitis. A positive genetic association was found between allele DRB3.2*24 and EBV for IMI by major pathogens and between DRB3.2*3 and IMI by minor pathogens. Several correlations between EBV for immunological assays and EBV for mastitis measures were significantly different from 0. Cows with low EBV for SCS tended to have neutrophils that had greater functional ability at maximal immunosuppression, low serum IgG1, and high numbers of circulating mononuclear cells. Immunological parameters, including physiological and molecular markers, are useful aids to understand the genetics of resistance to mastitis.

Crohn's disease and ulcerative colitis are associated with the DNA repair gene MLH1

OBJECTIVE

The purpose of this study was to determine whether there is an association between Crohn's disease and ulcerative colitis with MLH1.

SUMMARY BACKGROUND DATA

Identification of genes involved in the etiology of inflammatory bowel disease may lead to the development of markers that objectively can define disease and permit therapy. The treatment of Crohn's disease of the colon and ulcerative colitis also is complicated by difficulties in differentiating the two conditions.

METHODS

The DNA and clinical data were obtained on 126 unrelated individuals (45 Crohn's disease, 36 ulcerative colitis, and 45 control subjects without intestinal disease). Polymerase chain reaction products were analyzed by single-strand conformation polymorphisms (MLH1 exons 9, 11, 14, 15, and 16) and polyacrylamide gel electrophoresis (markers D3S1611 and D3S1768). All comparisons were analyzed by chi square test. The association between single haplotypes and disease was expressed as relative odds.

RESULTS

MLH1 exons 9, 11, 14, and 16 were monomorphic. Two, four, and six alleles were detected in MLH1 exon 15, D3S1611, and D3S1768, respectively. Significant associations were observed for MLH1 exon 15/D3S1611 haplotypes AB (OR = 5.5; p = 0.007) and BA (p = 0.002) with Crohn's disease and for haplotypes AB (OR = 4.0; p = 0.042), BA (p = 0.035), and BC (OR = 6.1; p = 0.016) with ulcerative colitis. Family history of inflammatory bowel disease was associated with D3S1768/D3S1611 (p = 0.05) and MLH1 exon 15/D3S1611 haplotypes (p = 0.03). D3S1611/D3S1768 haplotype CD (OR = 11.3; p = 0.03) was associated with disease, whereas MLH1 exon 15/D3S1611 haplotype AA (OR = 0.25; p = 0.02) was protective. Comparisons of MLH1 exon 15/D3S1611 haplotypes of Crohn's colitis and patients with ulcerative colitis were significant (p = 0.037).

CONCLUSIONS

This study identifies a novel genetic and clinical association between MLH1 and inflammatory bowel disease.

Bovine lymphocyte antigen class II alleles as risk factors for high somatic cell counts in milk of lactating dairy cows

Lactating Holstein cows (n = 1100) from 93 dairy herds in Iowa, Wisconsin, Minnesota, and Illinois were genotyped at the bovine lymphocyte antigen DRB3.2 locus by a genotyping system that used polymerase chain reaction and restriction fragment length polymorphisms. Milk samples were obtained after routine processing at a Dairy Herd Improvement Association facility and returned to the National Animal Disease Center for DNA extraction. Somatic cells were used to classify cows that had acutely elevated SCC (one test of SCC > 500,000; group 1), or chronically elevated SCC (three consecutive tests of SCC > 300,000 or two consecutive tests of > 500,000; group 2), or that were eligible as controls. For each cow in groups 1 and 2, controls were selected that were matched for breed, lactation, herd, and days in lactation (+/-60 d). A conditional model for stepwise logistic regression was used to determine the relative odds for the 10 alleles with a frequency > 3%. No significant associations were observed when the 292 cows in group 2 were compared with their 292 controls. Allele *16 was associated with an increased risk of disease for cows classified with an acute SCC (258 cases and 258 controls). This study has identified DRB3.2*16 as a potential risk factor for acute intramammary infection and established the use of Dairy Herd Improvement Association milk samples as a source of DNA that is useful for genetic epidemiologic studies.

Genetic association of bovine lymphocyte antigen DRB3 alleles with immunological traits of Holstein cattle

The associations between alleles at the BoLA (bovine lymphocyte antigen) DRB3 locus and 20 indicator traits of innate and adaptive immunity were investigated. Periparturient Holsteins (n = 127) were genotyped at the BoLA DRB3 locus using polymerase chain reaction and restriction fragment length polymorphism. Twenty-two alleles were observed in the study population, and frequencies ranged from 21 to < 1%. The same cattle were tested for a total of 20 innate and adaptive immunity traits, including lymphocyte response to mitogens (proliferative responses and Ig secretion), serum Ig, complement and conglutinin concentrations, total leukocyte count, and selected assays for neutrophil function. Models with gene substitution effects were used to investigate associations between BoLA DRB3 alleles and each of the immunological variables. Significant associations were found with 13 of the leukocyte functions tested. The number of immune parameters with significant associations with any allele ranged from 0 (with alleles DRB3.2*23 and DRB3.2*27) to 7 (with DRB3.2*8). The immunological parameter that had the most associations with alleles was serum IgG2 concentration with 6 alleles. One group of 4 alleles (representing 46% of the total allele frequency) was uniformly associated with increased IgM and complement and decreased mononuclear cell numbers. Thus, we demonstrated that the BoLA DRB3 genotype can influence measures of innate and adaptive immunity.

Cloning and sequencing of a cDNA encoding bovine intercellular adhesion molecule 3 (ICAM-3)

A cDNA encoding a putative bovine intercellular adhesion molecule (ICAM)-3, a ligand of the leukocyte integrin LFA-1 (CD11a/CD18), was sequenced and compared with human ICAM sequences. The 1635-bp bovine sequence codes for a protein of 544 amino acids (aa). This putative bovine ICAM-3 has five immunoglobulin (Ig)-like domains similar to human ICAM-1 and ICAM-3, and belongs to the Ig gene superfamily. The overall identities of the deduced aa sequence with those of human ICAM-3 and ICAM-1 are 61% and 58%, respectively. The predicted number and positions of Cys residues are all conserved between the bovine and human ICAM 3 aa sequences.

Assignment of five polymorphic ovine microsatellites to bovine syntenic groups

A panel of bovine somatic cell hybrids was used to map ovine microsatellites. Five of seven microsatellites were assigned to five bovine syntenic groups. These microsatellites were designated D5S10 (MAF23), D1S4 (MAF46), D13S1 (MAF18), D4S3 (MAF50), and DXS2 (MAF45), mapped to syntenic groups U3 (chromosome 5), U10 (chromosome 1), U11, U13, and the X chromosome, respectively. Two remaining sheep microsatellites amplified rodent DNA in the hybrid somatic cell panel, and were not assigned to bovine syntenic groups. Assignment of ovine-derived microsatellites to bovine syntenic groups provides additional evidence of the usefulness of microsatellites for mapping closely related species. The use of ovine and bovine microsatellites will aid in development of comparative genomic maps for these two species.

Isolation and mapping of polymorphic microsatellites in cattle

A partial plasmid library with bovine genomic inserts of about 500 basepairs was screened with a (dC-dA)n.(dG-dT)n oligonucleotide probe for the repeated nucleotide motif (CA)n. Eleven positive clones (0.3% of all colonies screened) were discovered and were subsequently isolated and sequenced. Eight microsatellite loci were analysed, one with eight alleles, one with seven alleles, three with six alleles, one with three alleles and two with two alleles. Six of these microsatellites were mapped by PCR-analysis of a panel of somatic hybrid lines.

Single-strand conformation polymorphisms (SSCPs) detected in five bovine genes

Polymerase chain reaction (PCR) primers designed to amplify bovine specific sequences of the arginine-vasopressin (ARVP), glycoprotein hormone alpha (CGA), cytochrome oxidase c subunit IV pseudogene (COXP), prochymosin (CYM), coagulation factor X (F10), inhibin beta A (INHBA), low density lipoprotein receptor (LDLR) and oxytocin (OXT) genes in hybrid cells were used in a search for single strand conformation polymorphisms. DNA from 75 animals comprising crossbred and 7 purebred breeds were analysed. ARVP, COXP, CYM, LDLR and OXT were found to be polymorphic while CGA, F10 and INHBA were not. Polymorphic regions were identified within 206 bp of exon 1 of ARVP, 582 bp of the pseudogene COXP, 253 bp of exon 9 of CYM, 519 bp of LDLR cDNA and 160 bp of the upstream regulatory region of OXT. This is the first report of bovine polymorphisms for these genes and an important step in our goal to incorporate type I comparative anchor loci into the bovine linkage map. Polymorphic loci were subsequently analysed in pedigreed full-sib families and shown to be inherited in a Mendelian fashion.

Microsatellite mapping of the gene causing weaver disease in cattle will allow the study of an associated quantitative trait locus

A genetic disease in cattle, progressive degenerative myeloencephalopathy (weaver disease), is associated with increased milk production. This association could result from population stratification, from a pleiotropic effect of a single gene, or from linkage disequilibrium between the gene causing weaver disease and a quantitative trait locus (QTL) for milk production. To test these hypotheses, we performed an extensive linkage study in a bovine pedigree segregating for the weaver condition and identified a microsatellite locus (TGLA116) closely linked to the weaver gene (zmax, 8.15; theta, 0.03). TGLA116 and, by extension, the weaver locus were assigned to bovine synteny group 13. This microsatellite can be used to identify weaver carriers, to select against this genetic defect, and to study the effect of the corresponding chromosomal region on milk production in Brown Swiss and other breeds of cattle.

Physical mapping of inhibin beta-A in domestic cattle

The gene for the beta-A subunit of inhibin (INHBA) was assigned to bovine syntenic group U13 by bovine x rodent hybrid somatic cells and the polymerase chain reaction (PCR). A 482-bp PCR fragment was used to clone a 37-kb cosmid. This cosmid was assigned to bovine Chromosome (Chr) 4 (BTA 4) by fluorescence in situ hybridization (FISH). This is the first assignment of a U13 marker to a bovine chromosome. A restriction fragment length polymorphism (RFLP) was detected with PstI within the INHBA cosmid.

Somatic cell mapping, polymorphism, and linkage analysis of bovine prolactin-related proteins and placental lactogen

The bovine prolactin gene family includes novel members expressed in the fetal placenta that are distinct from placental lactogen. In this study, we investigated the genetic organization of four members of this gene family (PRP1, PRP3, PRP6, and PRP10) as well as placental lactogen (PL). Using a bovine-rodent hybrid somatic cell panel, all five genes were assigned to bovine chromosome 23, which contains prolactin and the major histocompatibility group (BOLA). Restriction fragment length polymorphisms were detected by all probes in breeding populations with the restriction enzyme MspI, whereas no polymorphisms were detected with BamHI. EcoRI, HindIII, TaqI, and PstI produced polymorphic fragments with some but not all of the probes tested. A PRP10 polymorphism, which is apparently the result of a insertion/deletion event, detected polymorphism frequency differences between Bos indicus and Bos taurus. No recombinational events were observed with these probes and prolactin using linkage analysis involving 91 American Holsteins. The bovine prolactin gene family was incorporated into a linkage group containing CYP21. Our studies demonstrate that members of the bovine prolactin gene family have a close physical association with each other, and all members demonstrate genetic variability in the breeding population.

Somatic cell mapping of T-cell receptor CD3 complex and CD8 genes in cattle

Bovine genes encoding T-cell receptor, CD3, and CD8 molecules have been mapped to syntenic groups using bovine x rodent hybrid somatic cells. T-cell receptor alpha and delta chains were assigned to bovine syntenic group U5, and the beta and gamma genes were syntenic with each other and with markers on U13. CD3E and CD3D genes were syntenic with each other and located to bovine syntenic group U19. CD8 was most concordant with markers of syntenic group U16, although the concordancy was only 85% and the assignment must be regarded as tentative. The comparative gene maps of human chromosome 7, bovine syntenic group U13, and mouse chromosomes 6 and 13 suggest extensive evolutionary conservation.

Assignment of eight loci to bovine syntenic groups by use of PCR: extension of a comparative gene map

The polymerase chain reaction (PCR) has been combined with hybrid somatic cell technology to extend the bovine physical map. Eight bovine loci--glycoprotein hormone alpha (CGA), coagulation factor X (F10), chromogranin A (CHGA), low-density lipoprotein receptor (LDLR), human prochymosin pseudogene (CYM), oxytocin (OXT), arginine-vasopressin (ARVP), and cytochrome oxidase c subunit IV pseudogene (COXP)--were assigned to bovine syntenic groups with this approach. CGA was assigned to bovine syntenic group U2, F10 to U27, CHGA to U4 [bovine Chromosome (Chr) 21], LDLR to U22, CYM to U6, OXT and ARVP to U11, and COXP to U3 (bovine Chr 5). Seven of these genes, CGA, F10, CHGA, LDLR, OXT, ARVP, and CYM, further delineate regions of chromosomal conservation on human Chrs 6, 13, 14, 19, 20, 20, and 1, respectively. CHGA, OXT, and ARVP are unmapped in the mouse. Comparative mapping predicts the mouse CHGA will map to Chr 12, and mouse OXT and ARVP will map to mouse Chr 2. Furthermore, human CYM is predicted to be sublocalized to 1p32-q21. The primers developed for these eight loci will be useful for the development of hybrid somatic cell panels in the future as well as establishing a collection of bovine expressed sequence tags.

RASA contains a polymorphic microsatellite and maps to bovine syntenic group U22 on chromosome 7q2.4-qter

The bovine gene for the p21ras protein activator (RASA) includes in its 5' untranslated region a (TG)n repeat. Analysis of this (TG)n repeat by PCR amplification of genomic DNA revealed a four-allele polymorphism. A cDNA probe was used to assign RASA to the region 2.4-qter of bovine Chromosome (Chr) 7 by in situ hybridization. PCR analysis of a panel of somatic hybrid lines allowed the assignment of RASA to the unassigned syntenic group 22 (U22) and thus localizes U22 on Chr 7.