Impact of different severity hyperglycemia on erythrocyte rheological properties1

BACKGROUND

The triad "insulin resistance, prediabetes, diabetes" is three independent neologies with characteristic features and development. In addition, each are characterized by progression and the possibility of transition from one form to other. Due to the fact that diabetes is one of the common diseases associated with high rates of disability, it is necessary to improve diagnostic methods and educational regimens for successful prevention and treatment of the disease.

OBJECTIVE

We investigated Band 3 protein (B3p) level, osmotic resistance of erythrocytes, the total antioxidant activity (TAA) of blood serum, level of HbA1 in group patients with insulin resistance (IR), prediabetes, and Type 2 Diabetes Mellitus (T2DM) and comparative with health control group.

METHODS

We used original, accurate research methods that measure the essence of the studied quantities.

RESULTS

Disruptions of glucose and insulin homeostasis ay lead to the initiation of oxidative stress (in our study demonstrated by a decrease of TAA of blood serum) increased redox-sensitive PTP activity and aberrant band 3 phosphorylation, potentially leading to reduced erythrocyte deformability. At the same time glycation of Hb during T2DM may affect its cross-link with membrane proteins, in particular with B3p, and although appears to limit its cross-linking and decrease its clusterization ability, induces alterations in the cytoskeletal matrix, and thereby decrease erythrocytes' osmotic resistance making them more susceptible to hemolysis.

CONCLUSIONS

The osmotic resistance of the erythrocytes can be used as a sensitive marker for the detection of the early stages of hyperglycemia (prediabetes). This set of clinical trials will make it possible to identify diseases that make up the triad at an early stage. Early detection of disorders and continued research in this direction will help in the development of a diagnostic scheme for the prevention of such patients. Based on our data, research into anti-oxidation drugs is very important. With the help of the array of studies described in the article and antioxidant treatment, the likelihood of successful treatment will increase.

Pathophysiology of drug-induce peripheral neuropathy in patients with multiple myeloma

Multiple myeloma (MM) is a disease of unknown, complex etiology that affects primarily older adults. The course of the disease and the patients' survival time are very heterogeneous, but over the last decade, clear progress in the treatment of this incurable disease has been observed. Therapeutics that have proven to be highly effective include the immunomodulatory drug thalidomide and its newer analogs, lenalidomide and pomalidomide, as well as the proteasome inhibitors bortezomib and carfilzomib. However, the administration of some of the treatments, e.g., thalidomide or bortezomib, has also been associated with the occurrence of a serious and common adverse effect, drug-induced peripheral neuropathy. The mechanism of the development of the peripheral neuropathy is poorly understood. Nevertheless, one of its potential causes could be inadequate concentrations of crucial trophic factors, including neurotrophic and/or angiogenic factors, which are responsible for the proliferation, differentiation, survival and death of neuronal and nonneuronal cells.

Autologous cord blood transfusion in preterm infants - could its humoral effect be the kez to control prematurity-related complications? A preliminary study

Umbilical cord blood (UCB), rich in stem/progenitor cells, is partially eliminated from the bloodstream during childbirth because the cord is immediately clamped. We hypothesize that transfusion of autologous UCB to premature infants after delivery could serve as an adjuvant modality for preventing the development of prematurity-related complications. We randomly enrolled 20 preterm infants born before 32 weeks of gestational age (GA), all of whom developed anemia, necessitating transfusion of red blood cells (RBCs). Two groups, matched for GA, were selected: (1) infants (n = 5) who underwent UCB transfusion once within 5 days of birth (mean ± standard deviation, 3.2 ± 1.9 days) and (2) infants (n = 15) from whom UCB was not collected (e.g., lack of consent). The latter served as controls and received allogeneic RBC transfusions (7.8 ± 3.9 days after birth). Selected prematurity-related complications were monitored. Two weeks after UCB/RBC transfusion, peripheral blood samples were collected, and the concentrations of 41 selected growth factors and their receptors were analyzed using a multiplex protein array. UCB transfusions were found to be both feasible and tolerable. Intraventricular haemorrhage was diagnosed in two of five (40%) UCB recipients, but was found in thirteen of fifteen RBC recipients (86.7%). Twenty-two plasma proteins (e.g., insulin-like growth factors, stem cell factor, epidermal growth factors) were found with significantly different concentrations in UCB recipients compared to controls. Results demonstrate safety and feasibility of UCB transfusion in a small group of very premature neonates and should be interpreted as preliminary speculation. Transfusion of UCB could induce a specific humoral effects, and this could serve as an adjuvant modality for prevention of prematurity complications.

Cell and region specificity of Aryl hydrocarbon Receptor (AhR) system in the testis and the epididymis

Aryl hydrocarbon receptor (AhR) plays multiple important functions in adaptive responses. Exposure to AhR ligands may produce an altered metabolic activity controlled by the AhR pathways, and consequently affect drug/toxin responses, hormonal status and cellular homeostasis. This research revealed species-, cell- and region-specific pattern of the AhR system expression in the rat and human testis and epididymis, complementing the existing knowledge, especially within the epididymal segments. The study showed that AhR level in the rat and human epididymis is higher than in the testis. The downregulation of AhR expression after TCDD treatment was revealed in the spermatogenic cells at different stages and the epididymal epithelial cells, but not in the Sertoli and Leydig cells. Hence, this basic research provides information about the AhR function in the testis and epididymis, which may provide an insight into deleterious effects of drugs, hormones and environmental pollutants on male fertility.

The influence of the tumor necrosis factor-alpa-308G>A polymorphism on the efficacy of immunosuppressive therapy in patients after kidney transplantation

Cytokines play an important role in the immune response. The calcineurin inhibitors (cyclosporine CsA, tacrolimus TAC) widely used after renal transplantation to prevent allograft rejection are immunosuppressive drugs suppressing the production of cytokines. These drugs are characterized by interindividual variability and require monitoring their blood concentrations to predict their optimal dosage. Therefore, the aim of the study was to determine the correlation between therapeutic effects of immunosuppressants and the tumor necrosis factor-α (TNF-α)-308G>A polymorphism in renal transplant patients. A total of 412 patients receiving TAC and CsA were included in the study. Genotype frequencies were determined using the real-time PCR method. Patients with the GG genotype received higher doses of TAC as compared to carriers of the GA genotype (5.24 mg versus 3.35 mg) and had lower mean drug concentration in blood (5.86 ng/ml versus 6.92 ng/ml). Similar results were also obtained for CsA (GG: 185.33 mg versus GA: 153.30 mg, P < 0.05). The comparison of the TNF-α-308G>A polymorphism with the biochemical parameters did not reveal a potential risk for transplant rejection. These results indicate that the TNF-α-308G>A polymorphism may influence the dosage of immunosuppressive drugs in patients after transplantation as far as individualization of drug therapy is concerned.

Expression of neurotrophins and their receptors in human CD34+ bone marrow cells

Bone marrow (BM) CD34+ cells have the ability to secrete growth factors, cytokines, and chemotactic factors. We sought to better characterize this population and to investigate whether human BM CD34+ cells express neurotrophins (NTs) and their relevant receptors. We also compared their expression levels with BM nucleated cells (NCs). BM CD34+ cells were evaluated with respect to the expression levels of neurotrophins using qRT-PCR, immunofluorescent staining, and Western blotting. Next, the expression of specific (TrkA, TrkB, TrkC) and non-specific (p75NTR) neurotrophin receptors was detected by qRT-PCR and immunofluorescent staining in BM CD34+ cells. Using qRT- PCR, we show that even in the absence of inducing factors, CD34+ cells spontaneously express neurotrophins such as NGF, BDNF, NT-3, and NT-4. In addition, the NT expression levels in BM CD34+ cells are considerably higher than in NCs. Furthermore, we confirmed intracellular NT expression in BM CD34+ cells at the protein level using immunofluorescent staining and Western blotting. Using qRT-PCR, we found that immunomagnetically separated BM CD34+ cells spontaneously express high-affinity neurotrophin receptors (TrkA, TrkB, and TrkC) and the low-affinity receptor p75NTR at higher levels than NCs. Immunomagnetic CD34+ cell separation enables for the rapid and gentle sorting of stem/progenitor cells (SPCs) to prepare specific cell types for use in research and clinical applications. Our study suggests that BM CD34+ cells have the potential to support trophic factors for neural tissue and could contribute towards the protection and regeneration of neural cells.

Study on size effect of the silica nanospheres with solid core and mesoporous shell on cellular uptake

The properties of mesoporous silica nanoparticles including large surface area, large pore volume, easy surface functionalization and control of structure and pore size has made them promising drug carriers. In this study, the effect of different diameters (50 nm, 70 nm, 90 nm, 110 nm and 140 nm) of silica nanospheres with a solid core and mesoporous shell (mSiO2/SiO2) on cellular internalization in mouse fibroblast cells (L929) was evaluated. The physical properties of the nanostructures were characterized with various methods, such as transmission electron microscopy with x-ray dispersion spectroscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy and zeta potential. In order to define the cellular uptake, the nanostructures were labelled with fluorescent dye Alexa647, and imaging and quantitative methods were applied: laser scanning confocal microscopy, flow cytometry and thermogravimetry. Our results indicate that cellular uptake of the studied nanospheres is size-dependent, and nanospheres of 90 nm in diameter showed the most efficient cell internalization. Thus, particle size is an important parameter that determines cellular uptake of nanoparticles and should be considered in designing drug delivery carriers.

Prostaglandin E2 (PGE2) and thromboxane A2 (TXA2) synthesis is regulated by conjugated linoleic acids (CLA) in human macrophages

Conjugated linoleic acid (CLAs) are positional and geometric isomers of linoleic acid with have a potential anti-atherosclerotic and anti-inflammation properties. Metabolites of arachidonic acid--prostaglandins and thromboxans--are endogenous mediators of inflammation. Prostaglandin E(2) and thromboxan A(2) which are a products of two izoformes of cyclooxygenases (COX-1 and COX-2) in macrophages, play an important role in this process. COX-1 is a constitutive enzyme, whereas the COX-2 is inducible and its amount in the cell rapidly increases during inflammation (e.g. via NF kappaB pathway). The aim of the study was to test the effect of CLAs on cyclooxygenases (COX-1 and COX-2) activity, their mRNA expression and protein content in macrophages. Additionally the active form of the kappaB (NF kappaB) transcription factor was measured. For the experiments monocytes from monocytic cell line (THP-1) and from human venous blood were used. Monocytes were differentiated to macrophages and cultured with 30 muM CLAs or linoleic acid for 48 h. The COX-1 and COX-2 products - PGE(2) and TXB(2), were measured by ELISA method. The enzymes (COX-s) activity were estimated by spectroscopic method. mRNA expression and protein analysis were analysed by real-time PCR and Western blot technique. In macrophages cultured with CLAs reduction of TXB(2) and PGE(2) concentration was observed. Significant change in COX-2 expression in cells cultured with trans-10, cis-12 CLA (in macrophages obtained from peripheral blood) was observed. COX-1 inhibition was resulting from competition of CLA and linoleic acid with arachidonic acid.

A hypothesis for an embryonic origin of pluripotent Oct-4(+) stem cells in adult bone marrow and other tissues

Accumulating evidence demonstrates that adult tissues contain a population of stem cells that express early developmental markers such as stage-specific embryonic antigen and transcription factors Oct-4 and Nanog. These are the markers characteristic for embryonic stem cells, epiblast stem cells and primordial germ cells. The presence of these stem cells in adult tissues including bone marrow, epidermis, bronchial epithelium, myocardium, pancreas and testes supports the concept that adult tissues contain some population of pluripotent stem cells that is deposited in embryogenesis during early gastrulation. In this review we will discuss these data and present a hypothesis that these cells could be direct descendants of the germ lineage. The germ lineage in order to pass genes on to the next generations creates soma and thus becomes a 'mother lineage' for all somatic cell lineages present in the adult body.

Morphological and molecular characterization of novel population of CXCR4+ SSEA-4+ Oct-4+ very small embryonic-like cells purified from human cord blood: preliminary report

Recently, we purified from adult murine bone marrow (BM) a population of CXCR4(+), Oct-4(+) SSEA-1(+), Sca-1(+) lin(-) CD45(-) very small embryonic-like (VSEL) stem cells and hypothesized that similar cells could be also present in human cord blood (CB). Here, we report that by employing a novel two-step isolation procedure -- removal of erythrocytes by hypotonic lysis combined with multiparameter sorting -- we could isolate from CB a population of human cells that are similar to murine BM-derived VSELs, described previously by us. These CB-isolated VSELs (CB-VSEL) are very small (3-5 micro m) and highly enriched in a population of CXCR4(+)AC133(+)CD34(+)lin(-) CD45(-) CB mononuclear cells, possess large nuclei containing unorganized euchromatin and express nuclear embryonic transcription factors Oct-4 and Nanog and surface embryonic antigen SSEA-4. Further studies are needed to see if human CB-isolated VSELs similar to their murine BM-derived counterparts are endowed with pluripotent stem cell properties.

Association of cytokine gene polymorphisms and the release of cytokines from peripheral blood mononuclear cells treated with methotrexate and dexamethasone

Immunosuppressive drugs are widely used in the therapy of autoimmune disorders to suppress autoreactive T cells. The immune system is regulated by the release of cytokines. Cytokine are potent immunomodulatory molecules that act as mediators of inflammation and the immune response. Primarily secreted by T cell and macrophages, they influence cellular activation, differentiation, and function. Cytokine production is under genetic control. This is evidenced by the identification of polymorphism in cytokine gene regulatory regions that correlate with intra-individual variations in actual cytokine production. The aim of the study was to examine whether the individual differences in the polymorphic cytokine genes can lead to individual variation in release of cytokines after treatment with methotrexate and glucocorticosteroids. The study was carried out on mononuclear cells isolated from peripheral blood of 72 healthy subjects. The cells were activated with PHA and incubated with increasing concentrations of methotrexate (0.1-10 microM) and dexamethasone (0.01-1 microM). Levels of IL-2, IL-4, IL-6, IL-10, and TNFalpha in the culture supernatants were quantified by flow-cytometry using Th1/Th2 kit and correlated with cytokine gene polymorphisms. The increased concentrations of DEX resulted in comparable cytokine concentrations in cultures from subjects with low and high cytokine genotypes. Despite MTX treatment, the cytokine levels were significantly increased in individuals homozygous for the high producer allele. These results suggest that the cytokine gene variants may influence the efficacy of therapy with some immunosuppressive and anti-inflammatory drugs.

Cells enriched in markers of neural tissue-committed stem cells reside in the bone marrow and are mobilized into the peripheral blood following stroke

The concept that bone marrow (BM)-derived cells participate in neural regeneration remains highly controversial and the identity of the specific cell type(s) involved remains unknown. We recently reported that the BM contains a highly mobile population of CXCR4+ cells that express mRNA for various markers of early tissue-committed stem cells (TCSCs), including neural TCSCs. Here, we report that these cells not only express neural lineage markers (beta-III-tubulin, Nestin, NeuN, and GFAP), but more importantly form neurospheres in vitro. These neural TCSCs are present in significant amounts in BM harvested from young mice but their abundance and responsiveness to gradients of motomorphogens, such as SDF-1, HGF, and LIF, decreases with age. FACS analysis, combined with analysis of neural markers at the mRNA and protein levels, revealed that these cells reside in the nonhematopoietic CXCR4+/Sca-1+/lin-/CD45 BM mononuclear cell fraction. Neural TCSCs are mobilized into the peripheral-blood following stroke and chemoattracted to the damaged neural tissue in an SDF-1-CXCR4-, HGF-c-Met-, and LIF-LIF-R-dependent manner. Based on these data, we hypothesize that the postnatal BM harbors a nonhematopoietic population of cells that express markers of neural TCSCs that may account for the beneficial effects of BM-derived cells in neural regeneration.

Involvement of P-gp in the process of apoptosis in peripheral blood mononuclear cells

Multidrug resistance mediated by the drug-efflux protein P (P-gp) is one of mechanisms that cells use to escape death induced by drugs and other agents. The aim of the study was to evaluate the effect of P-gp inhibition on apoptosis of PHA-activated peripheral blood mononuclear cells (MNC) as well as apoptosis induced by methotrexate (MTX), dexamethasone (DEX), methylprednisolone (MP) and cortisone (COR). Apoptosis was quantified by flow cytometry using Annexin V/PI and terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL). P-gp expression was inhibited using verapamil (VER) and P-gp specific monoclonal antibodies (mAb). VER and mAb enhanced the apoptosis of PHA-activated MNC. Moreover these agents significantly increased the apoptosis induced by MTX, DEX, MP and COR. The results of this study suggest that P-gp is involved in the process of apoptosis in peripheral blood mononuclear cells.

The expansion of CD4+CD28- T cells in patients with chronic kidney graft rejection

CD4+CD28- T cells are oligoclonal lymphocytes rarely found in healthy subjects, but are present in high frequencies in patients with inflammatory diseases. Contrary to paradigm, they are functionally active and produce interferon gamma and cytolytic proteins, are cytotoxic in vessels and may contribute to tissue damage. The size of the peripheral blood CD4+CD28- T cell compartments was determined in 20 healthy individuals, 20 patients after renal transplantation with stable graft function, and 20 with chronic graft rejection by two-color FACS analysis. In patients with stable graft function, the median frequency of CD4+CD28- T cells was 3.1% and was significantly higher in comparison to the control group (1.4%) (P <.01). The highest subset CD4+CD28- cells was detected in patients with chronic graft rejection (10.65%). The amount of CD4+CD28- cells was significantly higher in this group in comparison to patients with stable graft function (P <.01). The evaluated number of CD4+CD28- cells in patients after renal transplantation, especially in graft recipients with chronic graft rejection, suggests a role of these cells in chronic graft destruction.

HEPARINIZED CADAVERIC ORGAN DONORS (HCOD)???A POTENTIAL SOURCE OF HEMATOPOIETIC CELLS FOR TRANSPLANTATION AND GENE THERAPY1

BACKGROUND

Hematopoietic stem cells (HSC) from unrelated HLA-matched heparinized cadaveric organ donors (HCOD) are a new potential source of cells for transplantation and gene therapy. In addition, these cells could also be used as adjuvant therapy to increase microchimerism and graft tolerance after transplantations of various solid organs. Our purpose was to develop an efficient method for harvesting hematopoietic cells from HCODs,

METHODS

Bone marrow cells were harvested from pelvic bones and/or vertebral bodies from 50 adult HCODs before or up to 3 hr after disconnecting the donor from the respirator. Subsequently, we evaluated the hematological and gasometric parameters of aspirated marrow samples as well as the proliferative potential, viability, and expression of CD34 and AC133 antigens on these cells.

RESULTS

We noticed that up to 2-3 hr after disconnecting the donor from the respirator bone marrow cavities do not clot and remain uninfected and that it is possible to aspirate bone marrow mononuclear cells in quantities sufficient to perform allotransplantation. Nevertheless, due to the developing hypoxia and acidosis of the hematopoietic microenvironment the number and proliferative potential of CD34+ and AC133+ cells gradually decreases. Hence, to obtain viable early hematopoietic cells, bone marrow should be aspirated without delay; optimally before HCOD is disconnected from the respirator or at the very latest 2 hr after organ harvest.

CONCLUSIONS

Collectively, our results show that early hemopoietic cells may be efficiently harvested from HCOD in large quantities and used for research and/or transplantation purposes. We postulate to create an international network of banks in which hemopoietic stem cells from HCODs could be preserved for therapeutic purposes.

Expression, regulation and function of AC133, a putative cell surface marker of primitive human haematopoietic cells

To explore the physiological significance of AC133 expression on human haematopoietic cells, we phenotyped normal and malignant human haematopoietic cells for AC133 expression, evaluated the utility of AC133 for isolating human stem/progenitor cells in comparison to other known early haematopoietic cell markers, investigated the role of AC133 in regulating hematopoiesis, and evaluated the possibility that MYB might regulate AC133. We found that while human CD34+ progenitor cells expressed AC133, expression was rapidly downregulated during differentiation. In apparent contrast, AC133 mRNA was detectable in cells isolated from CFU-Mix, BFU-E, CFU-GM and CFU-Meg colonies. Human cord blood CD34+ cells expressed AC133 at higher levels than their normal bone marrow counterparts. In apparent contrast to normal primitive haematopoietic cells, the AC133 protein was undetectable on cells from 24 different human haematopoietic cells lines, even though the majority of these cells expressed AC133 mRNA. Since CD34, AC133 and the c-kit (KIT) receptor are all co-expressed on human stem/progenitor cells, we compared the ability of monoclonal antibodies directed against each of these proteins to isolate early progenitor cells. Using these antibodies and magnetized particles in a standard immunoaffinity isolation protocol, we found that anti-CD34 and anti-KIT MoAbs could isolate > 80-90% of the clonogeneic cell population present in a given marrow sample. Anti-AC133 MoAbs recovered approximately 75-80% of CFU-GM and CFU-Meg, but only about 30% of CFU-Mix and BFU-E. Perturbation of AC133 expression with antisense oligodeoxynucleotides (AS ODN) resulted in transient downregulation of AC133 protein on human CD34+ cells but no apparent effect on cell survival or cloning efficiency ex vivo. Finally, downregulation of MYB expression with AS ODN had no effect on the AC133 expression at either the mRNA or protein level. Based on these results, we conclude that AC133 offers no distinct advantage over CD34 or c-kit as a target for immunoaffinity based isolation of primitive hematopoietic cells, that AC133 expression is not required for normal hematopoietic progenitor cell development in vitro, and finally that AC133 expression may not be MYB-dependent.

Evidence that human haematopoietic stem cells (HSC) do not reside within the CD34+KIT- cell population

Contradictory reports are published concerning the c-kit receptor (KIT) expression on human haematopoietic stem cells (HHSC). Therefore, the aim of this study was to reevaluate the expression of KIT on human early haematopoietic cells, and to study the distribution of HHSC among bone marrow mononuclear KIT+ and KIT- cells. First, we found that the detection sensitivity of the KIT expression on human HEL cells as well as CD34+ depends on the type of fluorochrome employed for the immunostaining (Cy5 > PE > FITC). Based on this observation, in our strategy for isolating human HHSC we employed a Cy-5 conjugated alpha-KIT MoAbs, which stained CD34+ cells in our preliminary studies the brightest. Accordingly, we labeled human BMMNC with PE-alpha-CD34 and Cy5-alpha-KIT MoAbs and subsequently sorted various subsets of labeled cells (CD34+KIT+, CD34+KIT- and CD34-KIT-). Cells sorted by FACS were then evaluated for their ability to engraft in the immunodeficient SCID mice model. We report here that only CD34+KIT+ cells, but not CD34+KIT- or CD34-KIT- were able to establish a human-murine haematopoietic chimerism in these animals. We found that SCID mice transplanted with CD34+ KIT+ cells, possessed approximately 5-11% of mononuclear cells, which expressed human CD45 antigen 4-5 weeks after transplantation in their bone marrow and, more importantly, early human haematopoietic progenitors from the myeloid and B-lymphoid lineages. Based on these results we conclude that KIT (CD117) is a very useful marker for identifying HHSC, and that HHSC, at least in our hands, are found in the KIT+ population of CD34+ cells.

An optimization study on unprogrammed cryopreservation of human CD34+ bone marrow cells and their subsequent storage in an -80 degrees C mechanical freezer

Among the factors which enable successful bone marrow transplantation, the ability to store and subsequently recover sufficient viable marrow cells to reestablish hematopoiesis is crucial. In most centers, marrow is typically prepared for long term storage by programmed, controlled rate freezing with subsequent placement into the vapor phase of liquid nitrogen. Though clearly effective, this procedure is time consuming and equipment intensive. Since cost containment is an important issue for all medical procedures, we evaluated the utility of a faster and less costly method to accomplish the same purpose. We found that when CD34+ bone marrow cells are immediately frozen and stored at -80 degrees C, the number and quality of stem/progenitor cells recovered after thawing was comparable to those reported recovered after conventional processing. Herein we report optimized conditions for cryopreserving and storing CD34+ bone marrow cells at -80 degrees C and for subsequent thawing of the stored product. With these methods post-thaw recovery of CFU-Mix, for example, equaled or exceeded 80% of predicted numbers, even after six months of storage. Further, though progenitor cell recovery does not necessarily correlate with speed of engraftment, these results nonetheless suggest that storage of human CD34+ cells at -80 degrees C in a mechanical freezer is a convenient, inexpensive, and reliable method for storing marrow for transplantation.

Comparison of the different strategies for cryopreserving and storage of the bone marrow CD34+ cells. Possibility of unprogrammed rate freezing and storage at -80 degrees C mechanical freezer

We have compared the efficiency of the different strategies allowing for a long term storage of a human CD34+ bone marrow cells. Accordingly, the aliquots of CD34+ cells isolated from bone marrow were frozen using: controlled rate freezing equipment, or freezer unprogrammed in a -80 degrees C mechanical freezer. After freezing, CD34+ cells were subsequently stored for one month in a liquid nitrogen tank at -196 degrees C or in mechanical freezer at -80 degrees C. We have found that both the viability and the recovery of clonogeneic progenitors of CD34+ cells samples stored at different temperature were similar. Therefore, regarding the costs and simplicity, we recommend the unprogrammed freezing and storage of human CD34+ cells at -80 degrees C in a mechanical freezer as a convenient, inexpensive, and reliable method for storing marrow for transplantation. This data also indirectly indicate that the aliquots of the CD34+ cells can be shipped frozen on dry ice (-80 degrees C), and that these cells will maintain viability under this conditions. Furthermore, in this study we have confirmed validity of our earlier observation that human CFU-Meg progenitors are more sensitive to cryopreservation.

Role of vascular endothelial growth factor (VEGF) and placenta-derived growth factor (PlGF) in regulating human haemopoietic cell growth

Vascular endothelial growth factor (VEGF) and placental derived growth factor (PlGF) stimulate cell proliferation and differentiation by binding to their specific receptors, Flk-1/KDR and Flt-1 respectively. Flk-1/KDR-deficient murine embryos manifest failure of blood-island formation and vasculogenesis. The aim of this study was to directly evaluate the importance of VEGF, PlGF/Flt-1 and Flk-1/KDR receptor ligand interactions in regulating normal and malignant human haemopoiesis. Addition of VEGF and PlGF failed to enhance survival or cloning efficiency of human haemopoietic progenitors isolated from adult bone marrows, fetal livers or cord blood samples. This finding may be explained by the apparent absence of mRNA encoding Flt-1 and Flk-1/KDR receptors on stem cell rich CD34+ c-kit-R+ Rh123(low) cells. Further studies revealed that Fit-1 R mRNA, but not Flk-1/KDR mRNA was first detectable in the more mature cells isolated from haemopoietic colonies. Accordingly, VEGF receptors are either absent, or expressed at very low level, on human haemopoietic stem/progenitor cells. Of interest, normal and malignant human haemopoietic cells appeared to secrete VEGF protein. However, in contrast to normal haemopoietic progenitors, VEGF co-stimulated HEL cell proliferation as well as CFU-GM colony formation from approximately 15% of the chronic myeloid leukaemia (CML) and acute myeloid leukaemia (AML) patients studied. Therefore, although VEGF appeared to have minimal effects on normal haemopoietic cell growth it would appear to drive malignant haemopoietic cell proliferation to some degree. Of more importance, however, we speculate that VEGF may play an very important role in leukaemogenesis by stimulating growth of vascular endothelium, thereby providing a sufficient blood supply to feed the growing haematological tumour.

CD34+, kit+, rhodamine123(low) phenotype identifies a marrow cell population highly enriched for human hematopoietic stem cells

We hypothesized that human hematopoietic cells displaying a CD34+, kit-, rhodamine123(low) phenotype would be highly enriched for cells with stem-like properties. To test this hypothesis, we employed fluorescence activated cell sorting (FACS) to isolate cells with this phenotype from normal light density marrow mononuclear cells (MNC). CD34+, kit+, rhodamine123(low) cells comprised from 0.05-0.01% of the total MNC population. They were small, had scant cytoplasm, and contained nuclei with dense, hyperchromatic chromatin and inconspicuous nucleoli. Additional immunophenotyping revealed that these cells were CD33-, CD38-, CD20-, and glycophorin A-. When plated in semisolid cultures containing optimal concentrations of IL-3, GM-CSF, KL, EPO, IL-6, and IL-1 these cells did not form colonies. However, when cultured over irradiated stromal cells, cobblestone areas were observed to form after 3 weeks, and harvested cells were able to initiate long-term cultures. To further demonstrate that these cells were indeed stem like, we also tested their ability to engraft and mature in immunocompromised (SCID) mice. Irradiated (400 cGy) SCID mice were transplanted with 2 x 10(3) candidate stem cells which were then injected with recombinant human growth factors every other day. Two months post-transplant the animals were sacrificed. PCR and FACS analysis of marrow and spleen cell samples revealed the presence of cells expressing human CD45 consistent with engraftment of human stem cells and the establishment of murine-human chimerism. Moreover, MNC isolated from transplanted mice formed unambiguously human BFU-E, CFU-GM and B cell colonies when stimulated with the appropriate growth factors. Accordingly, we have identified a relatively rapid and simple mechanism for isolating primitive human hematopoietic cells with stem cell-like properties. We anticipate that this strategy will be useful for experimental and therapeutic applications that require human stem cells in quantity.

Myb and ets proteins are candidate regulators of c-kit expression in human hematopoietic cells

Kit is a tyrosine kinase receptor that plays an important role in human hematopoietic cell growth. The promoter elements that modulate the gene's expression have not been extensively studied. Because of c-kit's acknowledged importance in hematopoiesis, we sought to address this issue in more detail. To perform these studies we analyzed a human c-kit 5' flanking fragment approximately 1 kilobase in length. Deletion constructs showed a region approximately 139 nucleotides upstream from the translation initiation site that was critical for promoter activity. A region containing a potential silencing element was also identified. Sequence analysis indicated several potential Myb- and Ets-binding sites. The functional significance of these sites was explored by showing that both wild-type Myb and Ets-2 protein, but not a DNA binding-deficient Myb mutant protein, bound to distinct 5' flanking fragments that included these sites. Furthermore, binding of recombinant Myb and Ets-2 protein to these fragments could be competed with an excess of double stranded oligodeoxynucleotides containing canonical, but not mutated, Myb- or Ets-binding sites. We also showed that the 5' flanking region of c-kit exhibited promoter activity in nonhematopoietic cells only when the cells were transfected with c-myb or ets-2 expression vectors. Moreover, Myb and Ets-2 coexpression in such cells augmented transactivation of c-kit promoter constructs in comparison to that observed in cells transfected with either construct alone. Promoter constructs lacking various Myb and Ets sites deleted were much less effective in this same system. Finally, Myb and Ets-2 mRNA expression was detected in CD34+, Kit low as well as CD34+, Kit bright cells. In aggregate, these data further define the human c-kit promoter's functional anatomy and suggest that Myb and Ets proteins play an important, perhaps cooperative, role in regulating expression of this critical hematopoietic cell receptor.

In vitro and in vivo evidence that ex vivo cytokine priming of donor marrow cells may ameliorate posttransplant thrombocytopenia

Thrombocytopenia is typically observed in patients undergoing hematopoietic stem cell transplantation. We hypothesized that delayed platelet count recovery might be ameliorated by increasing the number of megakaryocyte colony- forming units (CFU-Meg) in the hematopoietic cell graft. To test this hypothesis, we evaluated cytokine combinations and culture medium potentially useful for expanding CFU-Meg in vitro. We then examined the ability of expanded cells to accelerate platelet recovery in an animal transplant model. Depending on the cytokine combination used, we found that culturing marrow CD34+ cells for 7 to 10 days in serum-free cultures was able to expand CFU-Meg approximately 40 to 80 times over input number. Shorter incubation periods were also found to be effective and when CD34+ cells were exposed to thrombopoietin (TPO), kit ligand (KL), interleukin-1alpha (IL-1alpha), and IL-3 in serum-free cultures for as few as 48 hours, the number of assayable CFU-Meg was still increased approximately threefold over input number. Of interest, cytokine primed marrow cells were also found to form colonies in vitro more quickly than unprimed cells. The potential clinical utility of this short-term expansion strategy was subsequently tested in an in vivo animal model. Lethally irradiated Balb-C mice were transplanted with previously frozen syngeneic marrow mononuclear cells (10(6)/mouse), one tenth of which (10(5)) had been primed with [TPO, KL, IL-1a, and IL-3] under serum-free conditions for 36 hours before cryopreservation. Mice receiving the primed frozen marrow cells recovered their platelet and neutrophil counts 3 to 5 days earlier than mice transplanted with unprimed cells. Mice which received marrow cells that had been primed after thawing but before transplantation had similar recovery kinetics. We conclude that pretransplant priming of hematopoietic cells leads to faster recovery of all hematopoietic lineages. Equally important, donor cell priming before transplant may represent a highly cost-effective alternative to constant administration of cytokines during the posttransplant recovery period.

Effect of hepatocyte growth factor on early human haemopoietic cell development

Hepatocyte growth factor (HGF) stimulates cell proliferation, differentiation and migration by binding to its receptor, MET R. Whether the HGF/MET R axis plays an important regulatory role in human haemopoietic cell growth is an unresolved issue. To investigate this situation, we employed several complementary strategies including RT-PCR, FACS analysis, and mRNA perturbation with oligodeoxynucleotides (ODN). We found that very primitive, FACS sorted, CD34+ Kit+ marrow mononuclear cells (MNC) failed to express RT-PCR detectable MET R mRNA. In contrast, MET R expression was easily detectable by RT-PCR in marrow stroma fibroblasts, in cells isolated from BFU-E and CFU-GM colonies, and in unselected normal MNC. Subsequent FACS analysis revealed that MET R protein was detectable on approximately 5% of the latter cells. HGF, at concentrations of 1-50 ng/ml, had no demonstrable effect on survival or cloning efficiency of normal CD34+ MNC in serum-free cultures. Antisense ODN mediated perturbation of MET R mRNA expression in normal CD34+ MNC, with FACS documented decline in protein expression, had no effect on the ability of these cells to give rise to haemopoietic colonies of any lineage. We also examined the biology of HGF/MET R expression in malignant haemopoietic cells. Using the strategies described above, we found that MET R mRNA was expressed in many human haemopoietic cell lines, and that the protein was expressed at high levels on HTLV transformed T lymphocytes. Wild-type CML and AML blast cells also expressed MET mRNA, and HGF was able to co-stimulate CFU-GM colony formation in approximately 20% of cases studied. Therefore, although the HGF/MET R axis appears to be dispensable for normal haemopoietic cell growth, it may play a role in the growth of malignant haemopoietic progenitor cells.

Recombinant human thrombopoietin (TPO) stimulates erythropoiesis by inhibiting erythroid progenitor cell apoptosis

Thrombopoietin (TPO) has been reported to stimulate erythropoiesis, but the stimulatory mechanism has not been defined. To address this issue, we performed serum-free cell-culture experiments with recombinant human TPO and purified human progenitor cells. We found that TPO alone was able to stimulate the megakaryocyte colony formation in serum-free cultures, but erythroid colonies were never observed. Only in the presence of EPO (erythropoietin) +IL-3 was TPO able to stimulate a small increase (approximately 25%) in erythroid colony formation. Accordingly, we hypothesized that TPO might have an effect on erythroid progenitor cell viability, rather than a direct stimulatory effect. To test this idea, CD34+ cells were cultured for 7d in serum-free methylcellulose in the presence or absence of TPO, after which time KL+ EPO was added to the cultures. Cells which were pre-cultured for 7 d in the presence of TPO gave rise to approximately 6 times as many burst forming unit-erythroid (BFU-E) colonies as cells which were pre-cultured in the absence of TPO. Further, when primitive CD34+, Kit+ MNC were cultured for 3-7 d under serum-free conditions in the presence or absence of TPO, significantly fewer cells cultured in the presence of TPO displayed apoptotic changes when compared to cells cultured in the absence of TPO. Taken together, these results suggest that TPO has little direct stimulatory effect on erythroid progenitor cells, but might indirectly enhance erythropoiesis by preventing very early erythroid progenitor cells from undergoing apoptotic cell death.