Stem cells in genetically-engineered mouse models of prostate cancer

The cancer stem cell model proposes that tumors have a hierarchical organization in which tumorigenic cells give rise to non-tumorigenic cells, with only a subset of stem-like cells able to propagate the tumor. In the case of prostate cancer, recent analyses of genetically engineered mouse (GEM) models have provided evidence supporting the existence of cancer stem cells in vivo. These studies suggest that cancer stem cells capable of tumor propagation exist at various stages of tumor progression from prostatic intraepithelial neoplasia (PIN) to advanced metastatic and castration-resistant disease. However, studies of stem cells in prostate cancer have been limited by available approaches for evaluating their functional properties in cell culture and transplantation assays. Given the role of the tumor microenvironment and the putative cancer stem cell niche, future studies using GEM models to analyze cancer stem cells in their native tissue microenvironment are likely to be highly informative.

Migration and differentiation of neural cell lines transplanted into mouse brains

In the past few years, the plasticity of the regional specification of the CNS has been widely debated on the results from in utero transplantation. Two different results are reported with this transplantation method. One is that the distribution of transplanted cells is dependent on the donor origin, and the other is that the distribution is independent on the donor cell origin. The present study attempted to examine closely the plasticity of the regional specification by in utero transplantation method with clonal neural cell lines, 2Y-3t and 2Y-5o2b. These lines were established from a cerebellum of an adult p53-deficient mouse. Our results showed that transplanted cells migrated into various regions of the CNS and supported the independent distribution. Moreover, different distribution patterns of transplanted cells were observed between host sexes. Labeled cells were localized around the ventricle of neonatal host brains, where they were undifferentiated. In 2-3 weeks after birth, labeled cells were found in the brain parenchyma and some of them took neuronal morphology. In the rostral migratory stream (RMS), cells with unipolar or bipolar morphology were still undifferentiated. In other regions, labeled cells were often associated with blood vessels; the soma were on the surface of vessels, extending processes or neurites into surrounding brain parenchyma. Time-lapse imaging demonstrated that they were migrating with blood vessels.

Inhibition of skeletal metastasis by ectopic ERalpha expression in ERalpha-negative human breast cancer cell lines

Some hormone-independent breast cancers lack functional estrogen receptors (ERs) and show evidence of a more aggressive metastatic phenotype. A protective role of the ER has also been suggested in hormone-resistant breast cancer progression. In this study, we have investigated the effect of the ectopic expression of human ERalpha on the bone-metastatic potential of highly metastatic ERalpha-negative human breast cancer MDA-MB-231 and MDA-MB-435-F-L cell lines in an experimental model of bone metastasis in nude mice. ERalpha overexpression had no effect on the growth of both cell lines but reduced the expression of integrin alpha(v)beta(3) and the receptor activator of NF-kappaB, which are known to promote bone metastasis. A significant reduction in the incidence of osteolytic bone metastasis was observed by X-ray imaging of the legs and arms of mice inoculated with ERalpha-expressing clones of MDA-MB-231 cells in comparison to controls. Ectopic expression of ERalpha in MDA-MB-435-F-L cells also reduced their widespread skeletal metastasis to the legs, arms, spine, and mandible, as detected by whole-mouse enhanced green fluorescent protein imaging. Our study indicates for the first time that stable reintroduction of functional ERalpha in ERalpha-negative human breast cancer cells can inhibit their aggressive bone-metastatic potential in an experimental bone metastasis model.

Stem cell research: cloning, therapy and scientific fraud

Stem cell research has generated intense excitement, awareness, and debate. Events in the 2005-2006 saw the rise and fall of a South Korean scientist who had claimed to be the first to clone a human embryonic stem cell line. From celebration of the potential use of stem cells in the treatment of human disease to disciplinary action taken against the disgraced scientists, the drama has unfolded throughout the world media. Prompted by an image of therapeutic cloning presented on a South Korean stamp, a brief review of stem cell research and the events of the Woo-suk Hwang scandal are discussed.

Mathematical modelling of aerosolised skin grafts incorporating keratinocyte clonal subtypes

Severe burns can be very traumatic for the patient, and while burns caused by industrial or domestic accidents are common, there are also increasing numbers of burns associated with terrorism. A novel technique to assist in the healing process is to spray skin cells, keratinocytes, that are cultured from the patient's own tissue, directly onto the burn site. This process involves taking some undamaged skin from the patient, allowing the skin cells to proliferate rapidly in the laboratory over a period of 5-10 days, harvesting and separating the cells and then spraying them onto the burn. This paper deals with keratinocytes that have been cultured in vitro for a short period of time (early passage cultured cells). The spraying process has yet to be optimised with respect to the seeding density required for fastest re-epithelisation and thus there is a need for this process to be modelled. In this paper, we review some of the skin biology and develop a mathematical model of the growth patterns of cell colonies after they have been applied using a aerosolised technique. The model allows us to predict coverage over time and can be used as a decision support tool for clinicians.

Evidence of Donor-Derived Hematologic Malignancies after Hematopoietic Stem Cell Transplantation

Increasing the upper age limit for recipients of hematopoietic stem cell transplantation (HCT) naturally has also increased the age of the corresponding related donor population. Because aging is a risk factor for malignancies, the risk of transferring preexisting malignant or premalignant hemopoietic clones in the process of HCT might be expected to increase as well. Anecdotal clinical cases of malignancies derived from donor cells in patients undergoing HCT have been published since 1971. In this article, we report 12 new cases that fit 2 different categories: (1) cases in which clones with characteristics of lymphohemopoietic malignancies were transferred from the donors to the recipients and (2) cases in which the malignant clone evolved from healthy donor cells once transplanted into the recipient. Donors in the first group were significantly older than donors in the second group. A more systematic examination of the prevalence and biology of donor malignancies would merit study.

A clonal cell line from immortalized olfactory ensheathing glia promotes functional recovery in the injured spinal cord

Immortalized cell lines of olfactory ensheathing glia (OEG) that maintain the proregenerative properties of primary cultures provide an unlimited source of OEG for both basic and applied studies. Indeed, one specific immortalized rat OEG clonal line (TEG3) proved to be as good as primary OEG in promoting neuritogenesis and axon regeneration in culture models. Thus, we examined the capacity of TEG3 to promote axonal repair in an animal model of spinal cord injury, dorsal column crush. TEG3 cells can acquire astrocyte-like or Schwann cell-like morphology depending on the conditions under which they are cultured. In the injured spinal cord, prelabeled TEG3 survived for at least 10 weeks after grafting and they integrated into the spinal cord, adopting Schwann cell-like, astrocyte-like, or intermediate morphologies. In TEG3-transplanted animals, sensory projection axons grow into the lesion site and there was robust sprouting/axonal growth of the corticospinal tract, both into and beyond the lesion site, after crushing of the spinal cord-dorsal columns. TEG3-transplanted animals also recovered sensory and motor function in tape removal and beam walking behavioral tests. These data indicate that certain immortalized cell lines derived from a single cell can maintain the regenerative properties of primary OEG.

MAdCAM-1 is needed for diabetes development mediated by the T cell clone, BDC-2.5

The NOD-derived islet-reactive CD4(+) T cell clone, BDC-2.5, is able to transfer diabetes to neonatal non-obese diabetic (NOD) mice but is unable to transfer disease to either adult NOD or NOD scid recipients. Transfer of diabetes to adult recipients by BDC-2.5 is only accomplished by cotransfer of CD8(+) T cells from a diabetic donor. To understand why this CD4(+) T cell clone is able to mediate diabetes in neonatal but not the adult recipients we examined the ability of the clone to traffic in the different recipients. Our studies showed that MAdCAM-1 has a very different expression pattern in the neonatal and adult pancreas. Blockade of this addressin prevents the clone from transferring diabetes to neonatal mice, suggesting that the differential pancreatic expression of MAdCAM-1 in neonatal and adult pancreas provides an explanation of the differences in diabetes development.

Quantification of Self-Renewal Capacity in Single Hematopoietic Stem Cells from Normal and Lnk-Deficient Mice

Despite being a hallmark of hematopoietic stem cells (HSCs), HSC self-renewal has never been quantitatively assessed. Establishment of a clonal and quantitative assay for HSC function permitted demonstration that adult mouse HSCs are significantly heterogeneous in degree of multilineage repopulation and that higher repopulating potential reflects higher self-renewal activity. An HSC with high repopulating potential could regenerate approximately 1000 HSCs, whereas the repopulating activity of regenerated HSCs on average was significantly reduced, indicating extensive but limited self-renewal capacity in HSCs. Comparisons of wild-type mice with mutant mice deficient in the signal adaptor molecule Lnk showed that not only HSC numbers but also the self-renewal capacity of some HSCs are markedly increased when Lnk function is lost. Lnk appears to control HSC numbers by negatively regulating HSC self-renewal signaling.

Genetic variability of the mouse hepatoma cells MH-22a revealed by RAPD-PCR-fingerprinting under different conditions of cultivation

AIM

to study genetic variability in clonal lines of the mouse hepatoma MH-22a and the dependence of the capability of different clonal line cells for differentiation on the amount of genetic disturbances revealed by the RAPD-PCR method.

METHODS

The hepatoma MH-22a and its ten clonal lines were transplanted into subcutaneous connective tissue (SCT) and the eye anterior chamber (EAC) by injection of the cells to syngenic C3HA mice. The growth of transplants was checked in 15-20 days after transplantation. The tumors were fixed in neutral paraformaldehyde (10%), passed through ethanol of increasing concentrations, embedded in paraffin and stained by hematoxiline and eosine and Van Gisone. The genetic heterogeneity in the hepatoma cell population MH-22a and its clonal lines in vitro and in vivo was revealed by random amplified polymorphic DNA (RAPD-PCR). For the estimation of genetic variability revealed in the fingerprints was used the genetic variability index (GVI), based on the Bootstrep and Mikulinskaya's statistic programme.

RESULTS

The comparative analysis of the genetic structure of the clonal line populations in vitro and in vivo has revealed that the amount of clones with the high, intermediate, and low variability is approximately the same in both cases. It was also shown that GVI in various clonal lines in vitro correlated with their vital ability: the clones yielding clone lines had the lowest GVI. The same GVI value was found in the clonal lines proliferated in the EAC regardless of their capability for differentiation. Intraclonal analysis has shown that the highest values of changes revealed on fingerprints of the amplification of DNA products do not prevent from differentiation of tumor hepatoma cells in the EAC.

CONCLUSION

These data allow concluding that the mouse hepatoma cells MH-22a can preserve ability for differentiation in spite of significant changes in their genome.

Long-term correction of hyperglycemia in diabetic mice after implantation of cultured human cells derived from fetal pancreas

Type I diabetes is characterized by destruction of insulin-producing beta-islet cells in the pancreas resulting in hyperglycemia and associated morbidity. The successful treatment of diabetes by transplanted islets has resulted in renewed efforts to identify methods to augment islet availability. One approach is to identify and expand islet precursor cells able to later differentiate into functional endocrine cells. A population of cytokeratin 19-negative, vimentin-positive, insulin-negative, glucagon-negative, and nestin-positive cells was cultured from human fetal pancreas and passaged for over 20 population doublings. These cells were stimulated to form cell aggregates when grown on poly-D-lysine (PDL)-coated surfaces and then evaluated for differentiation potential using in vivo function as a surrogate marker for the presence of differentiated precursor cells. Streptozotocin-induced diabetic SCID mice implanted with PDL-induced cell aggregates were able to maintain glucose concentrations below 200 mg/dL for over 70 days (n = 5). In addition, human C-peptide was detectable in implanted animals but not in control animals. These findings show that a population of human fetal pancreas-derived cells (1) can be cultured and expanded in vitro, (2) can maintain the ability to differentiate into beta-islet-like cells, and (3) can correct hyperglycemia in a mouse model of diabetes. Further improvements in isolation, culture, and differentiation of human pancreas-derived beta-cell precursors may one day help to provide a novel source of islets for use in transplantation therapy to treat type I diabetes.

Unexpected severe calcification after transplantation of bone marrow cells in acute myocardial infarction

BACKGROUND

There has been a rapid increase in the number of clinical trials using unselected bone marrow (BM) cells or the mononuclear fraction of BM cells for treating ischemic heart diseases. Thus far, no significant deleterious effects or complications have been reported in any studies using BM-derived cells for treatment of various cardiac diseases.

METHODS AND RESULTS

Seven-week-old female Fisher-344 rats underwent surgery to induce acute myocardial infarction and were randomized into 3 groups of 16 rats, each receiving intramyocardial injection of either 7x10(5) DiI-labeled total BM cells (TBMCs), the same number of DiI-labeled, clonally expanded BM multipotent stem cells, or the same volume of phosphate-buffered saline in the peri-infarct area. Echocardiography 2 weeks after cell transplantation indicated intramyocardial calcification in 4 of 14 surviving rats (28.5%) in the TBMC group. Histological examination with hematoxylin and eosin staining and von Kossa staining confirmed the presence of extensive intramyocardial calcification. Alkaline phosphatase staining revealed strong positivity surrounding the calcified area suggestive of ongoing osteogenic activity. Fluorescent microscopic examination revealed that acellular calcific areas were surrounded by DiI-labeled TBMCs, suggesting the direct involvement of transplanted TBMCs in myocardial calcification. In contrast, in hearts receiving equal volumes of saline or BM multipotent stem cells delivered in the same manner, there was no evidence of calcification.

CONCLUSIONS

These results demonstrate that direct transplantation of unselected BM cells into the acutely infarcted myocardium may induce significant intramyocardial calcification.

Acute myeloid leukemia originates from a hierarchy of leukemic stem cell classes that differ in self-renewal capacity

Emerging evidence suggests cancer stem cells sustain neoplasms; however, little is understood of the normal cell initially targeted and the resultant cancer stem cells. We show here, by tracking individual human leukemia stem cells (LSCs) in nonobese diabetic-severe combined immunodeficiency mice serially transplanted with acute myeloid leukemia cells, that LSCs are not functionally homogeneous but, like the normal hematopoietic stem cell (HSC) compartment, comprise distinct hierarchically arranged LSC classes. Distinct LSC fates derived from heterogeneous self-renewal potential. Some LSCs emerged only in recipients of serial transplantation, indicating they divided rarely and underwent self-renewal rather than commitment after cell division within primary recipients. Heterogeneity in LSC self-renewal potential supports the hypothesis that they derive from normal HSCs. Furthermore, normal developmental processes are not completely abolished during leukemogenesis. The existence of multiple stem cell classes shows the need for LSC-targeted therapies.

Regeneration of the Infarcted Heart With Stem Cells Derived by Nuclear Transplantation

Nuclear transfer techniques have been proposed as a strategy for generating an unlimited supply of rejuvenated and histocompatible stem cells for the treatment of cardiac diseases. For this purpose, c-kit-positive fetal liver stem cells obtained from cloned embryos were injected in the border zone of infarcted mice to induce tissue reconstitution. Cloned embryos were derived from somatic cell fusion between nuclei of cultured LacZ-positive fibroblasts and enucleated oocytes of a different mouse strain. We report that regenerating myocardium replaced 38% of the scar at 1 month. The rebuilt tissue expressed LacZ and was composed of myocytes and vessels connected with the coronary circulation. Myocytes were functionally competent and expressed contractile proteins, desmin, connexin43, and N-cadherin. These structural characteristics indicated that the new myocytes were electrically and mechanically coupled. Similarly, the formed coronary arterioles and capillary structures contained blood and contributed, therefore, to tissue oxygenation. Cardiac replacement resulted in an improvement of ventricular hemodynamics and in a reduction of diastolic wall stress. These beneficial effects were obtained by stem cell transdifferentiation and commitment to the cardiac cell lineages. Myocardial growth was independent from fusion of the injected stem cells with preexisting partner cells. In conclusion, c-kit-positive stem cells derived by nuclear transfer cloning restore infarcted myocardium. Although problems currently plague nuclear transplantation, including the potential for epigenetic and imprinting abnormalities, stem cells derived from cloned embryos are sufficiently normal to repair damaged tissue in vivo. Importantly, the magnitude of myocardial regeneration obtained in this study is significantly superior to that achieved with adult bone marrow cells.

Somatic cell nuclear transfer

Embryos produced by nuclear transfer from a patient's somatic cell offer one potential source of embryonic stem cells for treatment of human degenerative diseases. As with all of the approaches to such therapy, this has both strengths and weaknesses. The cells would be histocompatible with the patient's cells, be expected to have a normal life span, and in principle be a source of any other cell type. However, the time taken and the costs involved in the isolation of the appropriate cell population would probably prohibit large-scale application. Clones have been produced from the cells of adults of five species, but similar studies in at least five other species have produced early embryos, but not offspring. A variety of somatic cells have been used as successful nuclear donors. The present procedures have proved to be repeatable, but are very inefficient when typically between 1% and 4% of reconstructed embryos develop to adulthood. The inefficiency is the accumulated effect of failure at all stages of development. There may be differences between species and donor cell type in the precise pattern of loss. This outcome is assumed to reflect the inappropriate expression of a large number of genes whose lethal effect is exerted at different stages. Improvements in the efficiency may depend upon understanding those mechanisms in the early embryo that establish the precise chromatin structure that governs development.

Regulatory CD8+ T cells fine-tune the myelin basic protein-reactive T cell receptor V beta repertoire during experimental autoimmune encephalomyelitis

A significant number of self-reactive T cell clones escape thymic negative selection and are released into the periphery, where some are potentially pathogenic. The clonal expansion of self-reactive T cells is known to be limited during initial antigen encounter by apoptotic or anergic mechanisms, regulatory CD4+ T cells, and cytokines. Here we report that superimposed on these mechanisms, during the evolution of autoimmunity in experimental autoimmune encephalomyelitis (EAE), CD8+ T cells are induced, which fine-tune the peripheral self-reactive T cell receptor (TCR) repertoire. We assayed the myelin basic protein-reactive TCR repertoire in naive, EAE-recovered mice as well as EAE-recovered mice depleted of CD8+ T cells by TCRV beta surface expression, complementarity-determining region 3 length distribution, and complementarity-determining region 3 sequencing analysis. In EAE-recovered mice, certain myelin basic protein-reactive CD4+V beta 8.2+ clones are significantly decreased and this decrease is not observed if CD8+ T cells were depleted from these mice. The clones that persist in CD8+ T cell-intact mice are highly diverse in contrast to the clones expanded in CD8+ T cell-depleted mice, which are dominated by the significant outgrowth of a few clones. Importantly, the T cell clones that expand in the absence of CD8+ T cell control are enriched in potentially pathogenic self-reactive T cell clones capable of inducing EAE in vivo.

Muscle stem cells differentiate into haematopoietic lineages but retain myogenic potential

Muscle-derived stem cells (MDSCs) can differentiate into multiple lineages, including haematopoietic lineages. However, it is unknown whether MDSCs preserve their myogenic potential after differentiation into other lineages. To address this issue, we isolated from dystrophic muscle a population of MDSCs that express stem-cell markers and can differentiate into various lineages. After systemic delivery of three MDSC clones into lethally irradiated mice, we found that differentiation of the donor cells into various lineages of the haematopoietic system resulted in repopulation of the recipients' bone marrow. Donor-derived bone-marrow cells, isolated from these recipients by fluorescence-activated cell sorting (FACS), also repopulated the bone marrow of secondary, lethally irradiated, recipients and differentiated into myogenic cells both in vitro and in vivo in normal mdx mice. These findings demonstrate that MDSC clones retain their myogenic potential after haematopoietic differentiation.

Connexin 37 gene is not mutated in lung carcinomas 3LL and CMT

Our previous studies have shown that intercellular communication mediated by gap junctions is impaired in most tumors as well as in cancer cell lines. However, connexin genes that encode gap junction proteins are only rarely mutated in cancer cells. On the other hand, it was reported that mutated Connexin 37 (Cx37) is the origin of shared tumor-associated antigenic octa-peptides (MUT 1 and MUT 2) of two independently derived lung carcinomas 3LL and CMT 64 of mouse origin. Two Cx37 mutations have been implicated: a Cys-54-Gln substitution in FEQNTAQP (MUT 1) and FEQNTAQA (MUT 2); an additional Pro-59-Ala substitution has been proposed in MUT 2. A Cys-54-Gln mutation in both tumors requires three base changes (TGT-to-CAG) to have occurred twice in independently derived tumors. Another complication stems from the fact that Cys 54, which is located in the extra-cellular domain is conserved in all connexins. Due to the important implications that these findings may have regarding the role of gap junctional communication in lung carcinomas as well as in the origin of tumor-associated antigens, we decided to re-examine these mutations. Thus, we PCR-amplified genomic DNA from 3LL and CMT and sequenced the coding region of Cx37 encompassing codon 54. We then analyzed the PCR products by digestion with the restriction enzyme MaeIII, to discern the presence of the putative mutation. Here we have unambiguously demonstrated that clones K(b)39.5 (39.5) and D122 of 3LL, and C6 and E9 of CMT 64, previously employed, have only normal Cx37 sequences, including those of codon 54. Therefore, we concluded that Cx37 is not mutated in 3LL and CMT 64 carcinomas.

Non-viral transfer approaches for the gene therapy of mucopolysaccharidosis type II (Hunter syndrome)

AIMS

Hunter syndrome is a rare X-linked lysosomal storage disorder caused by the deficiency of the housekeeping enzyme iduronate-2-sulphatase (IDS). Deficiency of IDS causes accumulation of undegraded dermatan and heparan-sulphate in various tissues and organs. Approaches have been proposed for the symptomatic therapy of the disease, including bone marrow transplantation and, very recently, enzyme replacement. To date, gene therapy strategies have considered mainly retroviral and adenoviral transduction of the correct cDNA. In this paper, two non-viral somatic gene therapy approaches are proposed: encapsulated heterologous cells and muscle electro-gene transfer (EGT).

METHODS

Hunter primary fibroblasts were co-cultured with either cell clones over-expressing the lacking enzyme or with the same incorporated in alginate microcapsules. For EGT, plasmid vector was injected into mouse quadriceps muscle, which was then immediately electro-stimulated.

RESULTS

Co-culturing Hunter primary fibroblasts with cells over-expressing IDS resulted in a three- to fourfold increase in fibroblast enzyme activity with respect to control cells. Fibroblast IDS activity was also increased after co-culture with encapsulated cells. EGT was able to transduce genes in mouse muscle, resulting in at least a tenfold increase in IDS activity 1-5 weeks after treatment.

CONCLUSION

Although preliminary, results from encapsulated heterologous cell clones and muscle EGT encourage further evaluations for possible application to gene therapy for Hunter syndrome.

SCID-repopulating cell activity of human cord blood-derived CD34- cells assured by intra-bone marrow injection

Precise analysis of human CD34-negative (CD34(-)) hematopoietic stem cells (HSCs) has been hindered by the lack of a simple and reliable assay system of these rare cells. Here, we successfully identify human cord blood-derived CD34(-) severe combined immunodeficiency (SCID)- repopulating cells (SRCs) with extensive lymphoid and myeloid repopulating ability using the intra-bone marrow injection (IBMI) technique. Lineage-negative (Lin(-)) CD34(-) cells did not show SRC activity by conventional tail-vein injection, possibly due to their low levels of homing receptor expression and poor SDF-1/CXCR4- mediated homing abilities, while they clearly showed a high SRC activity by IBMI. They generated CD34(+) progenies not only in the injected left tibia but also in other bones following migration. Moreover, they showed slower differentiating and reconstituting kinetics than CD34(+) cells in vivo. These in vivo-generated CD34(+) cells showed a distinct SRC activity after secondary transplantation, clearly indicating the long-term human cell repopulating capacity of our identified CD34(-) SRCs in nonobese diabetic (NOD)/SCID mice. The unveiling of this novel class of primitive human CD34(-) SRCs by IBMI will provide a new concept of the hierarchy in the human HSC compartment and has important implications for clinical HSC transplantation as well as for basic research of HSC.

Oscillation between B-lymphoid and myeloid lineages in Myc-induced hematopoietic tumors following spontaneous silencing/reactivation of the EBF/Pax5 pathway

B lymphomagenesis is an uncontrolled expansion of immature precursors that fail to complete their differentiation program. This failure could be at least partly explained by inappropriate expression of several oncogenic transcription factors, such as Pax5 and Myc. Both Pax5 and c-Myc are implicated in the pathogenesis of non-Hodgkin lymphomas. To address their role in lymphomagenesis, we analyzed B-cell lymphomas derived from p53-null bone marrow progenitors infected in vivo by a Myc-encoding retrovirus. All Myc-induced lymphomas invariably maintained expression of Pax5, which is thought to be incompatible with terminal differentiation. However, upon culturing in vitro, several cell lines spontaneously down-regulated Pax5 and its target genes CD19, N-Myc, and MB1. Unexpectedly, other B-cell markers (eg, CD45R) were also down-regulated, and markers of myeloid lineage (CD11b and F4/80 antigen) were acquired instead. Moreover, cells assumed the morphology reminiscent of myeloid cells. A pool of F4/80-positive cells as well as several single-cell clones were obtained and reinjected into syngeneic mice. Remarkably, pooled cells rapidly re-expressed Pax5 and formed tumors of relatively mature lymphoid phenotype, with surface immunoglobulins being abundantly expressed. Approximately half of tumorigenic single-cell clones also abandoned myeloid differentiation and gave rise to B lymphomas. However, when secondary lymphoma cells were returned to in vitro conditions, they once again switched to myeloid differentiation. This process could be curbed via enforced expression of retrovirally encoded Pax5. Our data demonstrate that some Myc target cells are bipotent B-lymphoid/myeloid progenitors with the astonishing capacity to undergo successive rounds of lineage switching.

Adoptive transfer of an anti-MART-1(27-35)-specific CD8+ T cell clone leads to immunoselection of human melanoma antigen-loss variants in SCID mice

The identification of appropriate mouse models could be useful in carefully evaluating the actual role of the in vivo development of antigen-loss variants during antigen-specific vaccine therapy of human tumors. In this study we investigated the level of efficacy of a MART-1/Melan-A-specific CD8+ T cell clone against its autologous melanoma in a severe combined immunodeficiency (SCID) mouse model, in which the tumor cells expressed in vivo heterogeneous and suboptimal levels of MART-1. The subcutaneous co-injection of the MART-1/Melan-A-reactive T cell clone A42 with MART-1/Melan-A+ autologous human melanoma cells into SCID mice caused a total inhibition of tumor growth. However, the systemic treatment with A42 clone lymphocytes resulted in only 50-60% inhibition of tumor growth, although the T cell clone targeted the tumors and the MART-1+ cells virtually disappeared from the tumors. This study suggests that an immunotherapy based on the expansion of an antigen-specific T cell clone generated in vitro is highly efficient in abolishing tumor growth when the target antigen is fully expressed, but leads to in vivo immunoselection of antigen-loss variants in the presence of suboptimal levels of antigen expression. Furthermore, this work shows that human tumors/SCID mouse models may be useful in evaluating the in vivo efficacy of adoptive immunotherapies.

Autoimmune encephalomyelitis and uveitis induced by T cell immunity to self beta-synuclein

Beta-synuclein is a neuronal protein that accumulates in the plaques that characterize neurodegenerative diseases such as Parkinson's and Alzheimer's diseases. It has been proposed that immunization to peptides of plaque-forming proteins might be used therapeutically to help dissociate pathogenic plaques in the brain. We now report that immunization of Lewis rats with a peptide from beta-synuclein resulted in acute paralytic encephalomyelitis and uveitis. T cell lines and clones reactive to the peptide adoptively transferred the disease to naive rats. Immunoblotting revealed the presence of beta-synuclein in heavy myelin, indicating that the expression of beta-synuclein is not confined to neurons. These results add beta-synuclein to the roster of encephalitogenic self Ags, point out the potential danger of therapeutic autoimmunization to beta-synuclein, and alert us to the unsuspected possibility that autoimmunity to beta-synuclein might play an inflammatory role in the pathogenesis of neurodegeneration.

Adoptive T cell therapy using antigen-specific CD8+ T cell clones for the treatment of patients with metastatic melanoma: in vivo persistence, migration, and antitumor effect of transferred T cells

Adoptive T cell therapy, involving the ex vivo selection and expansion of antigen-specific T cell clones, provides a means of augmenting antigen-specific immunity without the in vivo constraints that can accompany vaccine-based strategies. A phase I study was performed to evaluate the safety, in vivo persistence, and efficacy of adoptively transferred CD8+ T cell clones targeting the tumor-associated antigens, MART1MelanA and gp100 for the treatment of patients with metastatic melanoma. Four infusions of autologous T cell clones were administered, the first without IL-2 and subsequent infusions with low-dose IL-2 (at 0.25, 0.50, and 1.0 x 10(6) unitsm(2) twice daily for the second, third, and fourth infusions, respectively). Forty-three infusions of MART1MelanA-specific or gp100-specific CD8+ T cell clones were administered to 10 patients. No serious toxicity was observed. We demonstrate that the adoptively transferred T cell clones persist in vivo in response to low-dose IL-2, preferentially localize to tumor sites and mediate an antigen-specific immune response characterized by the elimination of antigen-positive tumor cells, regression of individual metastases, and minor, mixed or stable responses in 8 of 10 patients with refractory, metastatic disease for up to 21 mo.

Effective anti-tumor adoptive immunotherapy: utilization of exogenous IL-2-independent cytotoxic T lymphocyte clones

To attain one of the final goals for cancer immunotherapy, cytotoxic T lymphocyte (CTL) clones were selected on the basis of exogenous IL-2 independence after limiting dilution culture from mixed lymphocyte tumor cell culture cells of FBL-3 tumor-immune spleens. About 10% of the clones could be propagated up to >5 times by weekly passages in the presence of splenic feeder and stimulating tumor cells. Two of the representative FBL-3-specific CTL clones that were able to undergo the fifth passage were expanded in large numbers for adoptive transfer by two rounds of a weekly passage with medium containing IL-2. FBL-3-specific CTL clones thus obtained showed a strong ability to eliminate the established tumors when transferred into tumor-bearing nude mice. In addition, the cells were recovered from the mouse spleen even 8 months after the transfer. The most striking differences between the CTL clones used in this experiment and those maintained conventionally in the presence of IL-2 were the abilities to produce IL-2 by themselves and the high expression level of the integrin molecule, VLA-4, that disappeared when cultured completely in the continuous presence of IL-2 in vitro during 12 weeks. In addition, concomitant with the disappearance of exogenous IL-2 independence and VLA-4 expression, the CTL clones lost their capacity to eradicate the tumor in vivo. Thus, the higher capacity of CTL clones to produce IL-2 on their own seemed to be correlated with the in vivo efficacy for tumor eradication and the long-term maintenance of their physiological profiles typical of memory T cells.

The protective immune response to heat shock protein 60 of Histoplasma capsulatum is mediated by a subset of V beta 8.1/8.2+ T cells

Immunization with recombinant heat shock protein 60 (rHsp60) from Histoplasma capsulatum or a region of the protein designated fragment 3 (F3) confers protection from a subsequent challenge in mice. To determine the T cell repertoire involved in the response to Hsp60, T cell clones from C57BL/6 mice immunized with rHsp60 were generated and examined for Vbeta usage by flow cytometry and RT-PCR. Vbeta8.1/8.2(+) T cells were preferentially expanded; other clones bore Vbeta4, -6, or -11. When Vbeta8.1/8.2(+) cells were depleted in mice, Vbeta4(+) T cell clones were almost exclusively isolated. Measurement of cytokine production demonstrated that nine of 16 Vbeta8.1/8.2(+) clones were Th1, while only three of 13 non-Vbeta8.1/8.2(+) clones were Th1. In mice immunized with rHsp60, depletion of Vbeta8.1/8.2(+), but not Vbeta6(+) plus Vbeta7(+), T cells completely abolished the protective efficacy of Hsp60 to lethal and sublethal challenges. Examination of the TCR revealed that a subset of Vbeta8.1/2(+) clones that produced IFN-gamma and were reactive to F3 shared a common CDR3 sequence, DGGQG. Transfer of these T cell clones into TCR alpha/beta(-/-) or IFN-gamma(-/-) mice significantly improved survival, while transfer of other Vbeta8.1/8.2(+) clones that were F3 reactive but were Th2 or clones that were not reactive to F3 but were Th1 did not confer protection. These data indicate that a distinct subset of Vbeta8.1/8.2(+) T cells is crucial for the generation of a protective response to rHsp60.

Suppression of in vivo tumorigenicity of rat hepatoma cell line KDH-8 cells by soluble TGF-beta receptor type II

We have previously reported that transforming growth factor beta (TGF-beta) produced by rat hepatoma cell line KDH-8 cells suppressed the interleukin-2 (IL-2) production of T cells and the tumoricidal activity of macrophages in KDH-8 tumor-bearing rats and that the inhibition of TGF-beta production by low-dose bleomycin restored these activities significantly. In this study, we established three transfectant clones with stable expression of soluble TGF-beta receptor type II (sTRII), namely KT1, KT2 and KT3, and one with an empty vector used as control vector (KV), and then investigated the effects of sTRII on the tumorigenicity of KDH-8 cells and immune responses in syngeneic Wistar King Aptekman/Hok (WKAH) rats. We found that sTRII expressed in sTRII transfectants could abolish growth inhibition of Mv1Lu cells by TGF-beta1 produced by the cells themselves, and that tumor growth of KT2 and KT3 clones in vivo was suppressed significantly compared with that of parent, KV and KT1 clones. Furthermore, we demonstrated that IL-2 production of splenocytes and IL12p40 mRNA expression in tumor tissues were restored in rats inoculated with KT2 and KT3 clones, whereas such restoration was not observed in rats inoculated with parent, KV and KT1 clones. Combined with a low expression of sTRII in KT1 tumor tissues, these results suggest that sTRII may to some extent be able to abolish the tumor-promoting activity of TGF-beta, and imply that sTRII might have a therapeutic effect on TGF-beta-producing tumors.

Tumor-infiltrating CD4+ T lymphocytes express APO2 ligand (APO2L)/TRAIL upon specific stimulation with autologous lung carcinoma cells: role of IFN-alpha on APO2L/TRAIL expression and -mediated cytotoxicity

In the present report, we have investigated TRAIL/APO2 ligand (APO2L) expression, regulation, and function in human lung carcinoma tumor-infiltrating lymphocytes. Using a panel of non-small cell lung carcinoma cell lines, we first showed that most of them expressed TRAIL-R1/DR4, TRAIL-R2/DR5, but not TRAIL-R3/DcR1 and TRAIL-R4/DcR2, and were susceptible to APO2L/TRAIL-induced cell death. Two APO2L/TRAIL-sensitive tumor cell lines (MHC class I(+)/II(+) or I(+)/II(-)) were selected and specific CD4(+) HLA-DR- or CD8(+) HLA-A2-restricted CTL clones were respectively isolated from autologous tumor-infiltrating lymphocytes. Interestingly, although the established T cell clones did not constitutively express detectable levels of APO2L/TRAIL, engagement of their TCR via activation with specific tumor cells selectively induced profound APO2L/TRAIL expression on the CD4(+), but not on the CD8(+), CTL clones. Furthermore, as opposed to the CD8(+) CTL clone which mainly used granule exocytosis pathway, the CD4(+) CTL clone lysed the specific target via both perforin/granzymes and APO2L/TRAIL-mediated mechanisms. The latter cytotoxicity correlated with APO2L/TRAIL expression and was significantly enhanced in the presence of IFN-alpha. More interestingly, in vivo studies performed in SCID/nonobese diabetic mice transplanted with autologous tumor and transferred with the specific CD4(+) CTL clone in combination with IFN-alpha resulted in an important APO2L/TRAIL-mediated tumor growth inhibition, which was prohibited by soluble TRAIL-R2. Our findings suggest that APO2L/TRAIL, specifically induced by autologous tumor and up-regulated by IFN-alpha, may be a key mediator of tumor-specific CD4(+) CTL-mediated cell death and point to a potent role of this T cell subset in tumor growth control.

Comparison of IgG diffusion and extracellular matrix composition in rhabdomyosarcomas grown in mice versus in vitro as spheroids reveals the role of host stromal cells

The tumour extracellular matrix acts as a barrier to the delivery of therapeutic agents. To test the hypothesis that extracellular matrix composition governs the penetration rate of macromolecules in tumour tissue, we measured the diffusion coefficient of nonspecific IgG in three rhabdomyosarcoma subclones growing as multicellular spheroids in vitro or as subcutaneous tumours in dorsal windows in vivo. In subcutaneous tumours, the diffusion coefficient decreased with increasing content of collagen and sulphated glycosaminoglycans. When grown as multicellular spheroids, no differences in either extracellular matrix composition or diffusion coefficient were found. Comparison of in vitro vs in vivo results suggests an over-riding role of host stromal cells in extracellular matrix production subjected to modulation by tumour cells. Penetration of therapeutic macromolecules through tumour extracellular matrix might thus be largely determined by the host organ. Hence, caution must be exercised in extrapolating drug penetrability from spheroids and multilayer cellular sandwiches consisting of only tumour cells to tumours in vivo.

Differential experimental micrometastasis to lung, liver, and bone with lacZ-tagged CWR22R prostate carcinoma cells

LacZ-tagged human prostate carcinoma CWR22Rv1 cells metastasize spontaneously to lung, liver, and bone from subcutaneous primary tumors in athymic nude mice; these organs are 'natural' targets of metastasis for the human disease. To evaluate the mechanism(s) of metastasis to these organs, an experimental metastasis model was used by taking advantage of the ultrasensitive detection of lacZ. Within I h after tail vein injection, micrometastases were forming in lung, liver, bone, kidney, and brain with very different quantitative levels. The kinetics of loss of unstable micrometastases and retention of stable ones were also very different in these organs. After injecting suspensions of single cells, both whole-organ and serial-section staining for lacZ revealed considerable heterogeneity in cell number of individual lung micrometastases while micrometastases in liver contained only I or 2 cells. The size of individual bone micrometastases also suggested only 1 or 2 cells. Tumor cells could also be detected in the small blood vessels of the lung within minutes after injection. These studies indicate that lacZ-tagged CWR22Rv1 cells after tissue culturing contain subsets of cells capable of establishing transient micrometastases in lung, liver, and bone after direct injection into the animal's circulation. Moreover, the quantitative and qualitative properties of the micrometastases in the three organs differ significantly, suggesting different mechanisms for stabilization and fates of micrometastases in these organs.

Extensive in vivo self-renewal, long-term reconstitution capacity, and hematopoietic multipotency of Pax5-deficient precursor B-cell clones

Self-renewal, pluripotency, and long-term reconstitution are defining characteristics of single hematopoietic stem cells. Pax5(-/-) precursor B cells apparently possess similar characteristics. Here, using serial transplantations, with in vitro recloning and growth of the bone marrow-homed donor cells occurring after all transplantations, we analyzed the extent of self-renewal and hematopoietic multipotency of Pax5(-/-) precursor B-cell clones. Moreover, telomere length and telomerase activity in these clones was analyzed at various time points. Thus far, 5 successive transplantations have been performed. Clones transplanted for the fifth time, which have proliferated for more than 150 cell divisions in vitro, still repopulate the bone marrow with precursor B cells and reconstitute these recipients with lymphoid and myeloid cells. During this extensive proliferation, Pax5(-/-) precursor B cells shorten their telomeres at 70 to 90 base pairs per division. Their telomerase activity remains at 3% of that of HEK293 cancer cells during all serial in vivo transplantations/in vitro expansions. Together, these data show that Pax5(-/-) precursor B-cell clones possess extensive in vivo self-renewal capacity, long-term reconstitution capacity, and hematopoietic multipotency, with their telomeres shortening at the normal rate.

Transplanted clonal neural stem-like cells respond to remote photic stimulation following incorporation within the suprachiasmatic nucleus

Multipotent neural stem-like cells (NSCs) obtained from one brain region and transplanted to another region appear to differentiate into neuronal and glial phenotypes indigenous to the implantation site. Whether these donor-derived cells are appropriately integrated remains unanswered. In order to test this possibility, we exploited the suprachiasmatic nucleus (SCN) of the hypothalamus, site of a known circadian clock, as a novel engraftment target. When a clone of NSCs initially derived from neonatal mouse cerebellum was transplanted into mouse embryos, the cells incorporated within the SCN over a narrow gestational window that corresponded to the conclusion of SCN neurogenesis. Immunocytochemical staining suggested that donor-derived cells in the SCN synthesized a peptide neurotransmitter (arginine vasopressin) characteristic of SCN neurons. Donor-derived SCN cells reacted to light pulses by expressing immunoreactive c-Fos protein in a pattern that is appropriate for native SCN cells. This region-specific and physiologically appropriate response to the natural stimulation of a remote sensory input implies that donor-derived and endogenous cells formed true SCN chimeras, suggesting that exogenous NSCs engrafted to ectopic locations can integrate in a meaningful fashion.

Inhibition of tumor growth and metastatic spreading by overexpression of inter-alpha-trypsin inhibitor family chains

The inter-alpha trypsin inhibitor (ITI) family is a group of proteins built up from different combinations of I light chain (ITI-L) and 3 highly homologous heavy chains (ITI-HI, -H2 and -H3). To investigate a potential role of the ITI family chains in cancer and metastasis spreading, we engineered human H460M cell lines expressing both the green fluorescent protein (GFP) and one of these chains. These clones were subcutaneously injected in athymic nude mice, and lung metastasis number and primary tumor weight were determined after 28 days. Expression of the ITI-L chain considerably decreased tumor weight and fluorescent lung metastasis number. ITI-HI and ITI-H3 chain expression induced a significant decrease of metastasis number, whereas no decrease of tumor weight could be detected. In vitro, ITI-L expression significantly decreased chemotaxis and ITI-HI and ITI-H3 expression increased cell attachment. These results argue for the antitumoral or antimetastatic properties of ITI-L, -HI and -H3 chains.

Multiple hematopoietic cell lineages develop in vivo from transplanted Pax5-deficient pre-B I-cell clones

Pax5-deficient pre-B I-cell clones, transplanted into natural killer (NK)-cell-deficient RAG2(-/-) IL-2Rgamma(-/-) hosts, populate the NK-cell compartment with functional NK cells. NK-cell generation from Pax5(-/-) pre-B I cells is also observed in NK-cell-proficient Balb/c RAG2(-/-) hosts. In the same Balb/c RAG2(-/-) hosts, Pax5(-/-) pre-B I-cell clones not only populate the pre-B I-cell compartment and fill the deficient T-cell-lineage compartment in the thymus and the periphery of all hosts, as shown before, they also generate CD8alpha(-) and CD8alpha(+) dendritic cells (DCs), macrophages, and granulocytes in vivo in approximately half the hosts. In some recipients, practically all the mature myeloid cells are of Pax5(-/-) origin, indicating the effectiveness by which Pax5(-/-) pre-B I cells can compete with endogenous myeloid precursors. In a smaller percentage of hosts, the generation of Pax5(-/-) pre-B I-cell-derived erythrocytes is observed 4 to 6 months after transplantation. The results indicate that Pax5(-/-) pre-B I cells can develop in vivo in hosts that have undergone transplantation to erythroid, myeloid, and lymphoid cell lineages. Hence, the Pax5(-/-) mutation introduces an unusual instability of differentiation in pre-B I cells so that they appear to dedifferentiate as far back as the pluripotent hematopoietic stem cell.

relA over-expression reduces tumorigenicity and activates apoptosis in human cancer cells

We previously demonstrated that bcl-2 over-expression increases the malignant behaviour of the MCF7 ADR human breast cancer cell line and enhances nuclear factor-kappa B (NF-kappa B) transcriptional activity. Here, we investigated the direct effect of increased NF-kB activity on the tumorigenicity of MCF7 ADR cells by over-expressing the NF-kappa B subunit relA/p65. Surprisingly, our results demonstrated that over-expression of relA determines a considerable reduction of the tumorigenic ability in nude mice as indicated by the tumour take and the median time of tumour appearance. In vitro studies also evidenced a reduced cell proliferation and the activation of the apoptotic programme after relA over-expression. Apoptosis was associated with the production of reactive oxygen species, and the cleavage of the specific substrate Poly-ADP-ribose-polymerase. Our data indicate that there is no general role for NF-kappa B in the regulation of apoptosis and tumorigenicity. In fact, even though inhibiting NF-kappa B activity has been reported to be lethal to tumour cells, our findings clearly suggest that an over-induction of nuclear NF-kappa B activity may produce the same effect.

Persistent preswitch clonotypic myeloma cells correlate with decreased survival: evidence for isotype switching within the myeloma clone

Multiple myeloma (MM) is identified by unique immunoglobulin heavy chain (IgH) variable diversity joining region gene rearrangements, termed clonotypic, and an M protein termed the "clinical" isotype. Transcripts encoding clonotypic pre and postswitch IgH isotypes were identified in MM peripheral blood mononuclear cells (PBMCs), bone marrow (BM), and mobilized blood. For 29 patients, 38 BM, 17 mobilized blood, and 334 sequential PBMC samples were analyzed at diagnosis, before and after transplantation for 2 to 107 months. The clinical clonotypic isotype was readily detectable and persisted throughout treatment. Eighty-two percent of BM and 38% of PBMC samples also expressed nonclinical clonotypic isotypes. Clonotypic immunoglobulin M (IgM) was detectable in 68% of BM and 25% of PBMC samples. Nonclinical clonotypic isotypes were detected in 41% of mobilized blood samples, but clonotypic IgM was detected in only 12%. Patients with persistent clonotypic IgM expression had adverse prognostic features at diagnosis (lower hemoglobin, higher beta(2)-microglobulin) and higher numbers of BM plasma cells compared with patients with infrequent/absent clonotypic IgM. Patients with persistent clonotypic IgM expression had significantly poorer survival than patients with infrequent IgM expression (P <.0001). In a multivariate analysis, persistent clonotypic IgM expression in the blood correlated independently with poor survival (P =.01). In nonobese diabetic severe combined immunodeficiency mice, xenografted MM cells expressed clinical and nonclinical postswitch clonotypic isotypes. MM expressing clonotypic IgM engrafted both primary and secondary mice, indicating their persistence within the murine BM. This study demonstrates that MM clonotypic cells expressing preswitch transcripts are tied to disease burden and outcomes. Because MM pathology involves postswitch plasma cells, this raises the possibility that IgH isotype switching in MM may accompany worsening disease.

Comparison of lumbar spine fusion using mixed and cloned marrow cells

STUDY DESIGN

Prospective study on lumbar spine fusion using cloned and mixed marrow cells.

OBJECTIVE

To analyze the effectiveness of cloned osteoprogenitor cells in spine fusion and their differentiation in vivo using a traceable gene.

SUMMARY OF BACKGROUND DATA

Although autografts are currently the standard for stable spine fusion, supply is limited. Alternative graft materials need to be developed and evaluated.

METHODS

An osteoprogenitor cell, D1-BAG, cloned from mouse bone marrow and transduced with LacZ and neomycin resistance genes, and mixed marrow stromal cells from marrow blowouts were used in athymic rats to establish posterior spinal fusion; 2 x 10(6) cells in 100 microL Matrigel were implanted into the lumbar fusion bed in 36 animals, whereas Matrigel without cells was used in 16 animals as control. Rats were killed at 2, 3, 6, and 9 weeks, and the spines were evaluated by manual palpation, radiographs, and histology.

RESULTS

Two weeks after surgery radiopaque tissue was seen at transplantation sites with D1-BAG cells but not at sites with mixed marrow stromal cells. Successful spine fusion at 6 and 9 weeks was observed in 8 of 8 (100%) animals receiving DI-BAG cells, 4 of 8 (50%) in mixed marrow stromal cells, and 0 of 8 (0%) in control animals.

CONCLUSIONS

Compared with mixed marrow stromal cells, cloned osteoprogenitor cells can produce a larger amount of mature osseous tissue at an earlier time point during spine fusion.

Neuroprotection through delivery of glial cell line-derived neurotrophic factor by neural stem cells in a mouse model of Parkinson's disease

Neural stem cells (NSCs) have been proposed as tools for treating neurodegeneration because of their capacity to give rise to cell types appropriate to the structure in which they are grafted. In the present work, we explore the ability of NSCs to stably express transgenes and locally deliver soluble molecules with neuroprotective activity, such as glial cell line-derived neurotrophic factor (GDNF). NSCs engineered to release GDNF engrafted well in the host striatum, integrated and gave rise to neurons, astrocytes, and oligodendrocytes, and maintained stable high levels of GDNF expression for at least 4 months. The therapeutic potential of intrastriatal GDNF-NSCs grafts was tested in a mouse 6-hydroxydopamine model of Parkinson's disease. We found that GDNF-NSCs prevented the degeneration of dopaminergic neurons in the substantia nigra and reduced behavioral impairment in these animals. Thus, our results demonstrate that NSCs efficiently express therapeutic levels of GDNF in vivo, suggesting a use for NSCs engineered to release neuroprotective molecules in the treatment of neurodegenerative disorders, including Parkinson's disease.

Segregation of human neural stem cells in the developing primate forebrain

Many central nervous system regions at all stages of life contain neural stem cells (NSCs). We explored how these disparate NSC pools might emerge. A traceable clone of human NSCs was implanted intraventricularly to allow its integration into cerebral germinal zones of Old World monkey fetuses. The NSCs distributed into two subpopulations: One contributed to corticogenesis by migrating along radial glia to temporally appropriate layers of the cortical plate and differentiating into lamina-appropriate neurons or glia; the other remained undifferentiated and contributed to a secondary germinal zone (the subventricular zone) with occasional members interspersed throughout brain parenchyma. An early neurogenetic program allocates the progeny of NSCs either immediately for organogenesis or to undifferentiated pools for later use in the "postdevelopmental" brain.

Effective anti-tumor immunity induced in mice by a two-step vaccination protocol

BACKGROUND

TS/A cells (a Balb/c-derived tumor cell line), when injected into syngenic mice, give rise to rapidly growing tumors. In this study, a vaccination protocol was established which was able to elicit an immune response effective in controlling tumor growth.

MATERIALS AND METHODS

T19.2.1, a TS/A clone enginereed to stably express the mycobacterial cell wall-associated 19-kDa lipoprotein, was used as cell vaccine to immunize Mycobacterium Bovis-BCG pre-immunized Balb/c mice.

RESULTS

Mice receiving the two-step vaccination protocol were able to develop a strong anti-TS/A DTH reaction. Moreover, following a challenge with wild-type TS/A cells, some vaccinated animals rejected the tumor and the remaining animals showed a significantly increased survival in respect to controls.

CONCLUSION

The expression on TS/A cells of the mycobacterial 19-kDa antigen, recognised in the context of a pre-existing memory immune response, promotes the immunological recognition of the otherwise non-immunogenic wild-type TS/A cells.

Effect of tumour size on the in vivo growth inhibition of human colon carcinoma cells (HT-29) by colon mitosis inhibitor

We have previously shown that the colon mitosis inhibitor (CMI) suppresses the growth of transplanted HT-29 human colon carcinoma cells by approximately 40%. However, this effect declined along the time-course, as the inoculums progressively grew larger. In the present work we designed a test to assess the effectiveness of CMI as a function of tumour size. After ranking the terminal tumours by ascending size in the control group and the CMI group the growth inhibition was calculated at each rank position. The observed negative correlation between control tumour size and CMI inhibition (r = -0.94, p < 0.001) clearly demonstrated decreased growth inhibition with increased tumour size. Consequently, a retrospective analysis of the smallest and slowest growing tumours showed a profound growth inhibition (72-81%, p < 0.008), whereas a similar analysis of the large and fast growing tumours revealed no significant CMI effect. The increased CMI effect among slow growing tumours was apparently not associated with increased susceptibility to CMI in a subset of slow growing cells because the slow growing subclone HT-29A4 did not show increased CMI effect. Furthermore, HT-29A4 displayed a similar tendency of decreased CMI effect with increased tumour size (r = -0.70, p < 0.001). Interestingly, the same tendency of increased growth inhibitory effect on smaller tumours was also seen with retinoic acid and difluoromethylornithine (r = -0.96, p < 0.001). The apparent enhanced responsiveness among small tumours underlines the importance of early chemoprevention and chemotherapy.

V beta 6+ T cells are obligatory for vaccine-induced immunity to Histoplasma capsulatum

We examined TCR usage to a protective fragment of heat shock protein 60 from the fungus, Histoplasma capsulatum. Nearly 90% of T cell clones from C57BL/6 mice vaccinated with this protein were Vbeta6+; the remainder were Vbeta14+. Amino acid motifs of the CDR3 region from Vbeta6+ cells were predominantly IxGGG, IGG, or SxxGG, whereas it was uniformly SFSGG for Vbeta14+ clones. Short term T cell lines from Vbeta6+-depleted mice failed to recognize Ag, and no T cell clones could be generated. To determine whether Vbeta6+ cells were functionally important, we eliminated them during vaccination. Depletion of Vbeta6+ cells abrogated protection in vivo and upon adoptive transfer of cells into TCR alphabeta(-/-) mice. Transfer of a Vbeta6+, but not a Vbeta14+, clone into TCR alphabeta(-/-) mice prolonged survival. Cytokine generation by Ag-stimulated splenocytes from immunized mice depleted of Vbeta6+ cells was similar to that of controls. The efficacy of the Vbeta6+ clone was associated with elevated production of IFN-gamma, TNF-alpha, and GM-CSF compared with that of the Vbeta14+ clone. More Vbeta6+ cells were present in lungs and spleens of TCR alphabeta(-/-) on day 3 postinfection compared with Vbeta14+ cells. Thus, a single Vbeta family was essential for vaccine-induced immunity. Moreover, the mechanism by which Vbeta6+ contributed to protective immunity differed between unfractionated splenocytes and T cell clones.

Clonal variation in phenotype and life span of human embryonic fibroblasts (MRC-5) transduced with the catalytic component of telomerase (hTERT)

Expression of telomerase (hTERT) in certain cell types has been shown to extend cellular life span without malignant transformation. We studied the phenotype of 26 telomerase-transduced fibroblast clones (TTFC) generated from a mass culture of hTERT retrovirally transduced MRC-5 cells. About two-thirds of the transduced clones senesced at the expected time or shortly thereafter, despite high levels of expression of telomerase and telomere length maintenance. The remaining one-third of the clones were "immortalized" (followed for over 200 cumulative population doublings). All clones maintained a nontransformed phenotype: contact inhibition, anchorage dependency, lack of tumor formation in nude mice, dose dependency to serum and growth factors, low expression of a matrix metalloproteinase associated with metastatic invasion (MMP-9) and high expression of its inhibitor TIMP-1, and no cytogenetic abnormalities by G-banding. In addition, fibroblast-specific biological parameters, such as colony size, production of collagenase, and response to MMC and gamma radiation were tightly regulated at the clonal and subclonal levels.

Hoechst 33342 efflux identifies a subpopulation of cytogenetically normal CD34(+)CD38(-) progenitor cells from patients with acute myeloid leukemia

Efflux of Hoechst 33342 from normal hematopoietic cells identifies a "side population" (SP(+)) of negatively staining cells that, in the mouse, are largely CD34(-) and are enriched for primitive progenitors. To further characterize human SP(+) cells, blood or bone marrow from 16 patients with acute myeloid leukemia (AML) was analyzed for their presence, immunophenotype, and cytogenetic and functional properties, and for the relation between SP phenotype and multidrug resistance-1 (MDR-1) expression. The mean percentages of SP(+) and MDR(+) cells was 8.1% (range, 0.5%-29.9%) and 12.8% (range, 0%-54.8%), respectively, with no correlation between the 2 values. The percentages of SP(+) cells that were CD34(+)CD38(-), CD34(+)CD38(+), or CD34(-) were 12% (range, 0.4%-50%), 25% (range, 0.5%-96%), and 63% (range, 4%-99%). Cytogenetically abnormal cells were always detected in the SP(-)CD34(+)CD38(-) and SP(+)CD34(-) fractions, and abnormal colonies (CFC), long-term culture-initiating cells (LTC-IC), and nonobese diabetic-severe combined immunodeficiency (NOD/SCID) mouse leukemia-IC were detected in the former fraction. No progenitors were detected among SP(+)CD34(-) cells in any of these assays from 9 of 10 samples. In contrast, exclusively normal cells were detected in the SP(+)CD34(+)CD38(-) fraction from 9 of 15 samples, and CFC, LTC-IC, and multilineage engraftment in NOD/SCID mice from this subpopulation were also cytogenetically normal in 6 of 8, 6 of 7, and 2 of 2 cases studied, respectively. In contrast to murine studies, primitive progenitors are enriched among SP(+)CD34(+)CD38(-) cells from patients with AML. The molecular basis for Hoechst dye efflux is uncertain because it does not appear to be related to MDR-1 expression. (Blood. 2001;97:3882-3889)

Development of human lymphohematopoietic stem and progenitor cells defined by expression of CD34 and CD81

In this study, cord blood CD34(+) cells expressed CD81, a member of the transmembrane 4 superfamily, and were classified into 3 subpopulations on the basis of their expression levels: CD34(+)CD81(+), CD34(low)CD81(+), and CD34(+)CD81(high). The lymphohematopoietic activity of each subpopulation was then examined by using suspension and clonogenic cultures for hematopoietic potential, coculture with MS-5 cells for B-cell potential, organ cultures of thymus lobes from nonobese diabetic/severe combined immunodeficiency disease (NOD/SCID) fetal mice, coculture with stromal cells derived from NOD/SCID fetal-mouse liver tissue for natural killer (NK) cell and mast cell potentials, and xenotransplantation into NOD/SCID mice for long-term repopulating (LTR) ability. CD34(+)CD81(+) cells represented a heterogeneous population that had all the lymphohematopoietic activities, including NOD/SCID mouse-repopulating ability. CD34(low)CD81(+) cells were enriched in erythroid, megakaryocytic, and NK lineage potentials but had lost T-cell and B-cell potentials and LTR ability. The CD34(+)CD81(high) fraction was depleted of most lymphohematopoietic potentials except NK cell and mast cell potentials. Thus, along the differentiation cascade from CD34(+)CD81(+) lymphohematopoietic stem cells, an up-regulation of CD81 or a down-regulation of CD34 results in a change in lymphohematopoietic properties. CD81 may serve as a marker for defining developmental stages of lymphohematopoietic stem cells. (Blood. 2001;97:3755-3762)

A Glutamic Acid Decarboxylase 65-Specific Th2 Cell Clone Immunoregulates Autoimmune Diabetes in Nonobese Diabetic Mice

Several studies have provided indirect evidence in support of a role for beta cell-specific Th2 cells in regulating insulin-dependent diabetes (IDDM). Whether a homogeneous population of Th2 cells having a defined beta cell Ag specificity can prevent or suppress autoimmune diabetes is still unclear. In fact, recent studies have demonstrated that beta cell-specific Th2 cell clones can induce IDDM. In this study we have established Th cell clones specific for glutamic acid decarboxylase 65 (GAD65), a known beta cell autoantigen, from young unimmunized nonobese diabetic (NOD) mice. Adoptive transfer of a GAD65-specific Th2 cell clone (characterized by the secretion of IL-4, IL-5, and IL-10, but not IFN-gamma or TGF-beta) into 2- or 12-wk-old NOD female recipients prevented the progression of insulitis and subsequent development of overt IDDM. This prevention was marked by the establishment of a Th2-like cytokine profile in response to a panel of beta cell autoantigens in cultures established from the spleen and pancreatic lymph nodes of recipient mice. The immunoregulatory function of a given Th cell clone was dependent on the relative levels of IFN-gamma vs IL-4 and IL-10 secreted. These results provide direct evidence that beta cell-specific Th2 cells can indeed prevent and suppress autoimmune diabetes in NOD mice.