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Lifelong immunosuppressive therapy and inadequate sources of transplantable islets have led the islet transplantation benefits to less than 0.5% of type 1 diabetics. Whereas the potential risk of infection by animal endogenous viruses limits the uses of islet xeno-transplantation, deriving islets from stem cells seems to be able to overcome the current problems of islet shortages and immune compatibility. Both embryonic (derived from the inner cell mass of blastocysts) and adult stem cells (derived from adult tissues) have shown controversial results in secreting insulin in vitro and normalizing hyperglycemia in vivo. ESCs research is thought to have much greater developmental potential than adult stem cells; however it is still in the basic research phase. Existing ESC lines are not believed to be identical or ideal for generating islets or beta-cells and additional ESC lines have to be established. Research with ESCs derived from humans is controversial because it requires the destruction of a human embryo and/or therapeutic cloning, which some believe is a slippery slope to reproductive cloning. On the other hand, adult stem cells are already in some degree specialized, recipients may receive their own stem cells. They are flexible but they have shown mixed degree of availability. Adult stem cells are not pluripotent. They may not exist for all organs. They are difficult to purify and they cannot be maintained well outside the body. In order to draw the future avenues in this field, existent discrepancies between the results need to be clarified. In this study, we will review the different aspects and challenges of using embryonic or adult stem cells in clinical islet transplantation for the treatment of type 1 diabetes.

Blood platelets limit blood loss at sites of vascular injury by forming a mechanical plug. They are also involved in thrombosis, atherosclerosis, inflammation and metastasis. Platelet activation is essential for these physiological and pathological reactions and depends upon their adhesion to the vessel wall and attachment to each other in the aggregation process. The two known pathways of aggregation are mediated by the release of endoperoxides/thromboxane A2 and ADP which amplify platelet aggregation. Here we report the identification of a new pathway of aggregation which is mediated by the release of a metalloproteinase enzyme, gelatinase A.

A receptor for hyaluronan-mediated motility (RHAMM) has been shown to promote cell locomotion. Among human T lineage lymphocytes, RHAMM is expressed only on a subset of thymocytes, being absent on mature peripheral T cells from blood, spleen, and lymph node. Among thymocytes, RHAMM is selectively expressed on a subset of CD3+ CD45RA+R0+ cells, and functions in motility as shown by the ability of anti-RHAMM to reduce the speed of thymocyte locomotion from 11 microns/minute to 3 microns/min. Although freshly isolated multi-negative (MN) thymocytes (CD3-4-8-19-) lack RHAMM, its expression is induced on day 3 of culture in a variety of conditions that support differentiation, as assessed by acquisition of CD3. When MN thymocytes are cultured on plates coated with fibronectin, expression of RHAMM is prolonged, but on uncoated surfaces, its expression is transient and lost by day 7 of culture with PHA or IL-2. Culture of MN thymocytes on thymic epithelial layers, with or without IL-2, resulted in a lack of RHAMM expression. Because in the absence of epithelial cells, RHAMM is expressed, the effect appears to be one of inhibition. Although expression of RHAMM by MN thymocytes cultured with IL-2 on uncoated surfaces is transient, addition of cyclosporin A resulted in prolonged expression. These observations are consistent with the view that cyclosporin A inactivates a RHAMM-directed inhibitory mechanism. Mature peripheral blood T cells transiently express RHAMM upon culture with PHA, PMA, or IL-2. T cells that expressed RHAMM after culture with PMA alone lacked RHAMM when stimulated by mitogenic CD2 antibodies with or without CD28 antibody, indicating inhibition of RHAMM expression. Thus expression of RHAMM is regulated by a RHAMM-directed inhibitory mechanism induced by stimulation through CD2/CD28. A similar mechanism may operate in thymocyte/epithelial cell cultures. These results suggest the inhibition of RHAMM during early, presumably sessile, thymic progenitor development, followed by its induction during developmental stages when locomotion is required. The apparently strong negative regulatory control over RHAMM expression by microenvironmental factors and by known thymic and T cell signaling molecules supports this view.

1. Studies were performed regarding the effects of aluminum chloride and aluminum nitrate in concentrations of 5 mg/kg of body weight on the delta aminolevulinic acid dehydratase activity, iron level and hematological parameters. Wistar rats were exposed to these pollutants for 10, 20, 40 and 80 days. 2. The results demonstrated that aluminum chloride was more toxic than aluminum nitrate and both treatments brought about significant changes in these parameters in Wistar rats bone marrow. 3. The toxic effects of aluminum chloride and aluminum nitrate are manifested by a significant decrease of delta aminolevulinic acid dehydratase activity in the bone marrow of rats. 4. The iron level in bone marrow with aluminum chloride and aluminum nitrate gradually dropped after 10, 20, 40 and 80 days of intoxication. 5. In the peripheral blood a significant decrease in the erythrocyte count, hemoglobin level, hematocrit value and an increase in mean corpuscular hemoglobin (MCH) were also found in experimental animals.

In experimental studies on rabbits, osteogenic properties of stromal cells were confirmed after in vitro growth for 7 and 14 d. The cell suspension was percutaneously transplanted into a surgically produced bone defect in the rabbit's radius. The bone scar produced was X-rayed, and histologically and mineralogically examined after 10, 20 and 40 d follow-ups. Differences in the bone defect healing process (the healing rate and the type of bone tissue produced) were shown between the experimental and the control foreleg. Within the experimental foreleg, healing was considerably accelerated with compact bone formation on a membranous matrix, whilst in the control foreleg, a coarse, fibrous woven bone on a cartilaginous matrix was dominant.

The effects of haemodialysate and its three peptide fractions on acetylcholinesterase (AChE, E.C. 3.1.1.7) activity in erythrocytes from healthy subjects and patients with terminal renal insufficiency treated by repeated haemodialyses have been studied. It was shown that erythrocytes from haemodialysed patients display an increased activity of the enzyme if compared with those from healthy subjects. Neither haemodialysate nor any of its three peptide fractions, when incubated with erythrocytes from healthy subjects and from haemodialysed patients, have altered the activity of the enzyme, except for fraction III at the highest concentration. This fraction exerted an inhibitory effect on AChE activity of the erythrocyte derived from healthy subjects.

The effect of haemodialysate and its 3 peptide fractions on lactate dehydrogenase activity in erythrocytes was studied in patients treated by repeated haemodialysis for end-stage renal disease and in healthy subjects. Erythrocytes from dialyzed patients showed significantly lower LDH activity than those from healthy subjects. After a 3-h incubation with haemodialysate (675 and 450 micrograms protein/ml), or its peptide fraction III (270 and 190 micrograms protein/ml), a significant inhibition of LDH activity was observed. On the other hand, neither haemodialysate nor its peptide fractions inhibited LDH activity in red blood cells from patients with end-stage renal disease treated by repeated haemodialysis.

The aim of this study was to describe the effects of aluminum on the stromal cells of rat bone marrow using a combination of in vivo exposure and in vitro culture of bone marrow. The toxic effects of aluminum are manifested by a decrease in the erythrocyte count and hemoglobin level in the peripheral blood. Aluminum stimulated an increase in the number of fibroblasts while the macrophage count dropped. The number of adipocytes remained unaffected. An increase in mean corpuscular hemoglobin (MCH) was also found in the peripheral blood of experimental animals.

Effect of vasopressin, oxytocin and LHRH (10 and 20 pg/ml medium) on the proliferation and metabolism of cultured rat bone marrow stromal cells was investigated by methyl-3H-thymidine incorporation, cytochemistry and estimation of enzyme activities. Vasopressin did not change of the activity of tetrahydrofolate dehydrogenase (4HFDH), lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G6PD) and the level of reduced glutathione (GSH). However, the higher concentration of vasopressin significantly lowered the activity of acetylcholinesterase (AchE). As compared with the control cultures, stromal cells grown in the presence of oxytocin showed higher (at lower hormone concentration) and lower (at higher concentration) LDH activity as well as lower G6PD activity (only at higher concentration), while the activity of AchE and the level of GSH was not changed. LHRH significantly increased G6PD and AchE activity and decreased LDH activity in the cultured cells. As revealed by cytochemistry, LHRH specifically enhanced 4HFDH activity in reticular cells.

The effect of recombinant alpha interferon (INF) and of antilymphocyte globulin (ALG) to the colony stimulating factor (CSF) production was examined with in vitro culture of the bone marrow of healthy and of aplastic anaemia (AA) persons. In healthy persons the supernatant of lymphocytes preincubated with PHA and ALG was found to show a stimulating effect to clonogenic properties of marrow progenitors, the mentioned effect being not in proportion to the concentration value. Similar properties are shown by interferon in these persons. In patients with aplastic anaemia, a considerable stimulating ALG effect to the granulocytic formation of colonies and a lesser stimulating effect of interferon were shown.

The effect of copper in form of copper sulphate (CuSO4 x 5 H2O) was studied in the bone marrow cells of rats of Wistar strain in an in vitro culture. Evident differences between tissue cultures of the bone marrow cells were observed between the control and experimental groups. In the experimental group, the CFU-F colonies appeared as early as in 3rd day while in the control group in 5th day. Loosely arranged fibroblasts, macrophages and adipocytes also showed quantitative differences between groups. An increase in mean corpuscular hemoglobin (MCH) was also found in peripheral blood of experimental animals.

The study has been carried out on Wistar rats. The aim of the present study was to trace the effect of aluminum on erythroidal cells in bone marrow in rats. The number of proerythroblast after 10 days of experiment with aluminum slowly decreased up to 80 days of experiments. However, the number of basophilic erythroblasts after 10 days insignificantly increased but after 20 days gradually decreased up to 80 days of experiments. The bone marrow polichromatic erythroblasts after 10 days of experiment slightly decreased, however after 20, 40 and 80 days of experiments the values decreased significantly. The quality of orthochromatic erythroblasts after 10 days of experiments dropped and after 20, 40 and 80 days of experiments significantly decreased compared to the control value. Aluminum also brings about histological changes in the bone marrow. The statistical significant reductions of hemoglobin and hematocrit levels were found in the aluminum exposed rats.

The effect of recombinant alpha interferon (INF) to the colony stimulating factor (CSF) production was examined with in vitro culture of the bone marrow of patients with chronic granulocytic leukaemia (CGL). It could be found that addition of interferon into a suspension of preincubated phytohaemagglutinin (PHA) lymphocytes from peripheral blood represents an inhibity factor for colony and cluster formation in autologic human marrow cultures.

This study was carried out on male Wistar rats. The bone marrow activities of acetylcholinesterase (AchE-EC.3.1.1.7.), glutathione reductase (GR-EC.1.6.4.2.) and glucose-6-phosphate dehydrogenase (G6PD-EC.1.1.1.49.) were determined as affected by aluminium. The present experiments have revealed that within the first days there will be an increase in enzyme activity in the bone marrow. Simultaneously a decline in the activity of bone marrow could be observed which occurred later in the first course of the experiment.

The study has been carried out on male Wistar rats. The aim of the present study was to trace the effect of aluminium chloride and aluminium nitrate at concentration 10 microM and 20 microM on haem biosynthesis in vitro in bone marrow cell culture. The ability of haem biosynthesis in bone marrow cell culture after 48 h of experiments with aluminium chloride and aluminium nitrate significantly decreased in relation with the control value.

The experiments were carried out on "Swiss" mice which received injections of mercuric chloride. The organs examined included the spleen and bone marrow. The detection of mercury in the cells of the above organs was performed according to the histochemical method developed by Timm[13]. In both cases Timm's Ioethod failed, proving to be invalid for determination of the lowest mercuric concentrations. By use of the hXE technique, it was found that the minimum concentration of mercury in the tissue detectable by cyto-chemical methods amounts to 0.65-1.0 ppm.

The aim of this study was to determine the changes of the basic parameters of the erythrocyte system and the activity of some red blood cell (RBC) enzymes prior to and after a single physical effort leading to exhaustion. The study was carried out on male Wistar rats subjected to running on an electric rotating drum at a speed of 25 m/min. A single exercise caused a decrease in the RBC count, haemoglobin concentration (Hb) and haematocrit (Hct) by 21.9, 16.7 and 16.1%, respectively, and an increase in the reticulocyte count (Ret) by 661.5%. The exercise triggered also changes in the activities of some erythrocytic enzymes: pyruvate kinase (PK) activity increased by 12.4%, glucose-6-phosphate dehydrogenase (G6PD) by 37.8%, glutathione reductase (GR) by 30.8% and acetylcholinesterase (AChE) by 248.7%. These increases in the activities of RBC enzymes can be explained by an increase in the red cells turn-over.

The studies were carried out on male Wistar rats subjected to running within an electric rotating drum. The animals were divided into four experimental groups, differing one from another as to the duration of training. Each training session lasted 30 days. In the first group the daily run lasted 3 min, in the second group 5 min; in the third group, a 1 min run on the first day, and one min longer on each successive day; in the fourth group a 2 min run on the first day and for two min longer on each successive day. The determinations made prior to and after training included the peripheral blood erythrocyte (Er) and reticulocyte (Ret.) count, the hemoglobin concentration (Hb) and packed cell volume (PCV) and, determined by spectrophotometric methods, the activity of pyruvate kinase (PK), glucose-6-phosphate dehydrogenase (G6PD) and glutathione reductase (GR). Training induced an improvement of all enzymatic activities. The heavier the physical exertion, the more intensive was the enzymatic activity of red blood cells, due to the intensification of bone marrow erythropoetic activity under physical exertion and the appearance of young red cells in peripheral blood. All the experimental groups revealed a drop in erythrocyte count (Er), hemoglobin concentration (Hb), and hematocrit values (PCV), as well as an increase in the reticulocytes count (Ret) and in the activity of all the enzymes investigated. In the fourth group anemia was detected: prolonged endurance training decreased the RBC by 24.2%, Hb by 31.1%, PCV by 26.2% and increased the reticulocyte count by 881.6%.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of copper in form of copper sulphate (CuSO4 x 5 H2O) was studied in the bone marrow cells of rats of Wistar strain in an in vitro culture. Evident differences between tissue cultures of the bone marrow cells were observed between the control and experimental groups. In the experimental group, the CFU-F colonies appeared as early as in 3rd day while in the control group in 5th day. Loosely arranged fibroblasts, macrophages and adipocytes also showed quantitative differences between groups. An increase in mean corpuscular hemoglobin (MCH) was also found in peripheral blood of experimental animals.

The aim of the present study was to determine the relation between the exercise load used in training and the changes in the basic parameters of the erythrocytic system. The experiments were carried out on 33 Wistar rats (females and males). The animals were forced to run at a velocity of 1.47 km/h inside an electrically-driven rotating drum. The experiments were performed for 35 days. In the 1st - (females) and 2nd - (males) group the exercise period was prolonged by 1 min per day on successive days, and by 2 min per day in the 3rd - (females) and 4th - (males) group. Prior to and after the training period the haemoglobin concentration, haematocrit, erythrocyte and reticulocyte counts were determined in the venous blood. Reticulocytes were divided into four age groups and the percentage each particular age group was calculated. All the trained groups manifested a decrease in haemoglobin concentration, hematocrit values and erythrocyte count and a concomitant elevation of the reticulocyte count with a shift towards youngest forms was found. Rats of the 3rd and 4th groups developed post-exercise anaemia.

The effect of lead on the stromal cells of bone marrow in rats was studied in cultures in vitro. Toxic effects of lead were manifested by a decrease in erythrocyte count and hemoglobin level in peripheral blood. Lead stimulated an increase in the number of fibroblasts, while the macrophage count dropped. The number of adipocytes remained unaffected.

The effect of mercury and combined effect of mercury and DMSO on the activity of acetylcholinesterase of rat lymphocytes was studied during in vitro incubation. It was found that mercury is a very strong inhibitor of AchE. Dimethylsulphoxide performs a protective role for this enzyme. The activity of AchE in the lymphocytes treated with mercury and DMSO regardless of mercury concentration was similar to that in control series.

The toxicity of antifolate drug therapy on microenvironmental function of hemopoietic marrow stromal cells may be critical enough to justify the development of a simple cell culture model to appraise the dihydrofolate reductase (DHFR)/tetrahydrofolate dehydrogenase (EC 1.5.1.3) (4HFDH) enzymic system in individual stromal cells. The localization and pattern of expression of 4HFDH/DHFR in cultured bone marrow stromal cells were studied in situ in morphologically identifiable cells. The 4HFDH/DHFR expression varies quantitatively and qualitatively according to cell types and thus constitutes specific phenotypic patterns for fibroblastic stromal cells, endothelial cells, monocyte-macrophages, and osteoclast-like cells. Data indicate a good correlation between the labeling of the enzymic expression and the resistance of cells to methotrexate treatment. This conclusion is also supported by similar features shown by cell sublines bearing multiple DHFR gene copies. Levels of 4HFDH/DHFR expression in marrow stromal cells should provide useful markers underlining the effects of cytostatic drugs used in chemotherapy (for example, methotrexate injuries or resistance). The method can be applied to isolated cells, stromal colonies (fibroblast CFU), or whole adherent layers from marrow cultures. Moreover, with this method, enzymic reactions can be carried out in situ and visual correlations between a supportive microenvironment (hemopoietic foci) and the 4HFDH/DHFR levels on the stromal adherent layer are possible.

Stromal cells obtained from bone marrow of Wistar rats were cultured in liquid medium. The cultures were divided into control and experimental groups. After 24 h of culture, the medium was removed and replaced by a new one containing 10(-6) and 10(-9) M 4 beta-phorbol or phorbol 12,13-diacetate ester in the experimental cultures, or phorbol solvent alone in control cultures. After 7 days, the cultures were stained with Wright's stain or were subjected to cytochemical procedures for demonstration of nonspecific esterase, alkaline and acid phosphatases and diaphorase activities. The obtained results showed that phorbols stimulated proliferation: fibroblast colonies, fibroblasts, macrophages, immature reticular cells. The number of adipocytes was markedly lower in the experimental cultures. Phorbols stimulated activity of the investigated enzymes.