Transplantation of hematopoietic stem cells from the peripheral blood

Hematopoietic stem cells can be collected from the peripheral blood. These hematopoietic stem cells (HSC), or better progenitor cells, are mostly expressed as the percentage of cells than react with CD34 antibodies or that form colonies in semi-solid medium (CFU-GM). Under steady-state conditions the number of HSC is much lower in peripheral blood than in bone marrow. Mobilization with chemotherapy and/or growth factors may lead to a concentration of HSC in the peripheral blood that equals or exceeds the concentration in bone marrow. Transplantation of HSC from the peripheral blood results in faster hematologic recovery than HSC from bone marrow. This decreases the risk of infection and the need for blood-product support. For autologous stem-cell transplantation (SCT), the use of peripheral blood cells has completely replaced the use of bone marrow. For allogeneic SCT, on the other hand, the situation is more complex. Since peripheral blood contains more T-lymphocytes than bone marow, the use of HSC from the peripheral blood increases the risk of graft-versus-host disease after allogeneic SCT. For patients with goodrisk leukemia, bone marrow is still preferred, but for patients with high-risk disease, peripheral blood SCT has become the therapy of choice.     

Evidence for a selective migration of fetus-specific CD4+CD25bright regulatory T cells from the peripheral blood to the decidua in human pregnancy

During pregnancy, the maternal immune system has to tolerate the persistence of fetal alloantigens. Many mechanisms contribute to the prevention of a destructive immune response mediated by maternal alloreactive lymphocytes directed against the allogeneic fetus. Murine studies suggest that CD4(+)CD25(+) T cells provide mechanisms of specific immune tolerance to fetal alloantigens during pregnancy. Previous studies by our group demonstrate that a significantly higher percentage of activated T cells and CD4(+)CD25(bright) T cells are present in decidual tissue in comparison with maternal peripheral blood in human pregnancy. In this study, we examined the phenotypic and functional properties of CD4(+)CD25(bright) T cells derived from maternal peripheral blood and decidual tissue. Depletion of CD4(+)CD25(bright) T cells from maternal peripheral blood demonstrates regulation to third party umbilical cord blood cells comparable to nonpregnant controls, whereas the suppressive capacity to umbilical cord blood cells of her own child is absent. Furthermore, maternal peripheral blood shows a reduced percentage of CD4(+)CD25(bright)FOXP3(+) and CD4(+)CD25(bright)HLA-DR(+) cells compared with peripheral blood of nonpregnant controls. In contrast, decidual lymphocyte isolates contain high percentages of CD4(+)CD25(bright) T cells with a regulatory phenotype that is able to down-regulate fetus-specific and fetus-nonspecific immune responses. These data suggest a preferential recruitment of fetus-specific regulatory T cells from maternal peripheral blood to the fetal-maternal interface, where they may contribute to the local regulation of fetus-specific responses.     

妊娠梅毒患者外周血中Th17和Treg细胞水平及其临床意义分析

目的:探讨妊娠梅毒患者外周血中Th17和Treg细胞水平及其临床意义。方法:选择2015年4月至2016年5月我院收治的35例妊娠梅毒患者作为观察组,并选择同期进行孕检的健康孕妇30例作为对照组。分析和比较其外周血Th17和Treg细胞水平及其诊断妊娠梅毒的临床价值。结果:观察组患者外周血Th17水平显著高于对照组,而外周血Treg水平显著低于对照组(P0.05)。多因素logistic回归分析结果显示外周血Th17和Treg水平与妊娠梅毒发病具有明显相关性。外周血Th17诊断妊娠梅毒的AUC为0.776,95%CI为0.656～0.896,外周血Treg诊断妊娠梅的ROC曲线下的面积(area under curve,AUC)为0.947,95%CI为0.897～997,Th17+Treg诊断妊娠梅毒的AUC为0.960,95%CI为0.913～1.000;Th17和Treg单独检测分别和联合检测曲线下面积比较均具有显著差异(Z=-2.807、-0.375,P0.05);Th17+Treg联合检测的特异度、准确度分别为91.73%、93.28%,显著高于各指标单独检测(P0.05)。结论:妊娠梅毒患者外周血Th17细胞增多,Treg细胞减少,联合检测外周血Th17和Treg细胞水平诊断妊娠梅毒具有较高的准确度,可作为诊断妊娠梅毒的重要参考指标。     

IgM rheumatoid factor autoantibody and immunoglobulin-producing precursor cells in the bone marrow of humans

The natures of the IgM rheumatoid factor (RF)-, IgM-, and IgG-secreting cells in the human bone marrow as compared to the peripheral blood, have been investigated by (1) response to the polyclonal B-cell activator, the Epstein-Barr virus (EBV), (2) sensitivity to the S-phase specific antimetabolite hydroxyurea, (3) presence of the BA-1 and Ia antigens on the cell surface, and (4) cell size, as determined by counter flow elutriation. The EBV-inducible bone marrow IgM-RF precursors derived from medium to large B cells that were inhibited by hydroxyurea pretreatment. The marrow total IgM response derived from small to medium size cells, and was only partially inhibited by hydroxyurea. Hydroxyurea had no effect on IgM-RF or IgM synthesis by peripheral blood cells. These results indicate that the marrow EBV-induced IgM-RF response is not representative of the response by peripheral blood cells, moreover; the marrow RF secreting response arises from a dividing cell pool that may represent newly generated autoreactive B cells.     

The persistence of micronucleated erythrocytes in the peripheral circulation of normal and splenectomized Fischer 344 rats: implications for cytogenetic screening

Micronucleated erythrocytes are selectively removed from the peripheral circulation of normal rats. Splenectomy prevents this selective removal. In normal rats treated daily for 20 days with 0.2 mg/kg triethylenemelamine (TEM), micronucleated normochromatic (mature) erythrocytes did not accumulate in peripheral blood. In these same animals, the frequencies of micronucleated cells among polychromatic (newly formed) erythrocytes increased from 0.21 to 5.25 per thousand in peripheral blood and from 1.75 to 31.5 per thousand in bone marrow. Since both control and induced frequencies in peripheral blood were approximately 15% of those in bone marrow, the removal appears to be equally efficient for cells containing either spontaneously occurring or clastogen-induced micronuclei. In splenectomized rats treated daily for 11 days with 0.2 mg/kg TEM, the frequency of micronucleated normochromatic erythrocytes (NCEs) in the peripheral blood rose rapidly to 9 times the control value and remained elevated for 50-55 days, indicating a life span approximately equivalent to that of normal erythrocytes. Among splenectomized rats exposed to either 0.15 mg/kg triethylenemelamine, 6.5 mg/kg cyclophosphamide, or 300 mg/kg urethane for periods exceeding the erythrocyte life span, the incidences of micronucleated NCEs in the peripheral blood rose steadily from a control value of 1.0 per thousand to maximum values of 15.0, 12.7 and 8.9 per thousand, respectively. During these extended exposures, the mean frequencies of micronucleated polychromatic erythrocytes (PCEs) in peripheral blood increased from a spontaneous value of 0.9 per thousand to 23.0, 13.0 and 6.6 per thousand, respectively, reflecting the frequencies among PCEs in the bone marrow and approximating the maximum values among NCEs in the peripheral blood. Thus, the frequency of micronucleated erythrocytes in the peripheral blood of splenectomized rats can be used as an index of both acute and cumulative chromosomal damage, while in normal rats the use of peripheral blood for cytogenetic monitoring is restricted by the selective removal of these micronucleated cells.     

Measurements of the dielectric properties of peripheral blood mononuclear cells and trophoblast cells using AC electrokinetic techniques

The separation of trophoblast cells from the maternal circulation could provide a valuable diagnostic tool for prenatal diagnosis of genetic abnormalities. This has been attempted using antibody methods, but due to non-specificity of the antibodies, maternal cell contamination remains a problem. We have investigated the potential of dielectrophoretic separation methods as a means of isolating trophoblast cells from mixed peripheral blood mononuclear cells. To determine the potential of this method the dielectric properties of trophoblast cells and mixed peripheral blood mononuclear cells were measured using dielectrophoretic crossover and single cell electrorotation methods. Both dielectrophoretic crossover data and electrorotation data gave an average specific membrane capacitance of the peripheral blood mononuclear cells of 11.5 mF m(-2). Trophoblast cells prepared using three different methods had a higher average specific membrane capacitance in the range 13-18 mF m(-2). The differences in capacitance between the cell types could be exploited as the basis of an AC electrokinetic-based system for the separation of trophoblast cells from peripheral blood mononuclear cells.     

变应性鼻炎患者外周血中Tr1/Th3细胞的检测和分析

目的:检测变应性鼻炎(Allergic rhinitis,AR)患者和健康对照者外周血中IL-10+CD4+T细胞、TGF-β+CD4+T细胞(分别代表Tr1细胞和Th3细胞的特性)的比例,并探讨其在AR发病中的意义,为AR的治疗提供临床参考。方法:分离19例对粉尘螨过敏的AR患者和19例健康对照者外周血单个核细胞(PBMCs),采用流式细胞术分别检测外周血中IL-10+CD4+T细胞、TGF-β+CD4+T细胞的比例。结果:同健康对照者相比,AR患者外周血中IL-10+CD4+T细胞的比例显著降低[(1.66±0.48)%vs.(3.80.92)%,t=-9.08,P0.01)],AR患者外周血中TGF-β+CD4+T细胞的比例降低[(1.92±0.54)%vs.(4.76±1.12)%,t=-9.94,P0.01)]。结论:外周血中IL-10+CD4+T(Tr1)细胞比例的降低可能是AR发病的一个重要因素,提高AR患者外周血中分泌IL-10的Tr1细胞的比例可能在AR的治疗中具有重要意义。外周血中TGF-β1+CD4+T(Th3)细胞的比例显著降低,可能是AR发病的一个重要因素。但TGF-β1与AR关系的研究较少,特别是外周血中TGF-β1水平与AR的关系研究较少,需进一步研究。     

Human T cells in the SCID-hu mouse are phenotypically normal and functionally competent

SCID-hu mice are heterochimeric animals that are constructed by transplanting human fetal thymus (Thy), liver (Liv), and/or lymph nodes into congenitally immunodeficient C.B-17 scid/scid (SCID) mice. Sensitive and specific two-color flow cytometric assays were used to evaluate human lymphocytes from peripheral blood of SCID-hu mice. Kinetic studies presented in this report show long term T lymphopoiesis in SCID-hu mice. Approximately one-half of SCID-hu mice constructed with Thy and Liv tissue develop detectable levels of circulating human T cells by 4 mo after transplantation. The average level of circulating human cells in SCID-hu mice is generally less than 2% of the total lymphoid cells in the peripheral blood of these mice. Some SCID-hu mice with as high as 13% human lymphocytes, however, have been detected. Nearly all human cells in the peripheral blood of SCID-hu mice are CD3+ cells that express TCR-alpha beta. The percentages of gamma delta+, CD4+, CD8+, CD25+, CD69+, and Leu-8+ cells among CD45+ cells in SCID-hu blood are similar to the levels found in adult peripheral blood. On average, 74% of SCID-hu T cells express CD45RA and 18% express CD29. Functional studies demonstrate that cells from SCID-hu Thy/Liv grafts or human T cells from SCID-hu peripheral blood are functionally competent to respond to mitogens or allogeneic human cells in vitro. They are similar to fetal thymocytes or adult T cells, respectively, in these responses. These studies demonstrate that the SCID-hu mouse is a useful model for the analysis of human immune differentiation and function in vivo.     

Stimulation of a cell-mediated cytotoxic response to FeLV-induced T cell lymphomas in the cat

Nonspecific cell-mediated cytotoxicity was examined in the peripheral blood and spleens of normal and vaccinia virus-infected adult domestic cats. Natural cytotoxic (NC)-like cells, as measured by lysis of vaccinia- or HSV-infected, adherent cat tongue cells, were found in both the spleen and peripheral blood of normal, nonimmune cats. Cytotoxicity was expressed in a 16-hr assay but not in a 4-hr assay. Natural killer (NK)-like cells, as measured by lysis of an FeLV-induced lymphoid tumor cell line (FL-74) growing in suspension, were found in the spleen but not PBL, and required a 16-hr assay for expression. Infection with vaccinia virus did not increase the activity of feline NC-like cells in either the peripheral blood or the spleen. NK-like function, however, was increased. Cytotoxicity peaked 6 days post-infection and required a 16-hr assay for maximal expression of cell lysis. Furthermore, a cell with cytotoxic characteristics of the spleen NK-like cell appeared at low levels in the circulation at 6 days post-vaccinia infection. NK-like cells from vaccinia-infected cats showed some cytotoxicity for FL74 targets in a 4-hr assay. The cat thus possesses at least two functionally different populations of naturally cytotoxic cells. NC-like cells are found in the spleen and peripheral blood, lyse virus-infected monolayer targets, and are not activated by infection. NK-like cells are found in the spleen, lyse-lymphoid tumor targets, and can be activated by infection, with their peak activity occurring 6 days after infection.     

Mobilization of human hematopoietic stem/progenitor-enriched CD34+ cells into peripheral blood during stress related to ischemic stroke

The bone marrow-derived stem/progenitor cells were demonstrated to play an important role in a regeneration of damaged tissue. Based on these observations we asked whether the stroke-related stress triggers mobilization of stem/progenitor cells from the bone marrow into the peripheral blood, which subsequently could contribute to regeneration of damaged organs. To address this issue, the peripheral blood samples were harvested from patients with ischemic stroke during the first 24 hrs as well as after the 48 (2nd day) and 144 hrs (6th day) since the manifestation of symptoms. In these patients we evaluated the percentage of hematopoietic stem/progenitor-enriched CD34+ cells by employing flow cytometry and the number of hematopoietic progenitor cells for the granulocyto-monocytic (CFU-GM) and erythroid (BFU-E)-lineages circulating in peripheral blood. We concluded that stress related to ischemic stroke triggers the mobilization of hematopoietic stem/progenitor cells from the bone marrow into peripheral blood. These circulating stem/progenitor cells may play an important role in the process of regeneration of the ischemic tissue.     

Depressed lectin-dependent cell-mediated cytotoxicity against adherent HEP-2 cells in patients with carcinoma of the uterine cervix

Lectin-dependent cell-mediated cytotoxicity of peripheral blood mononuclear cells from patients with uterine cervix carcinoma was evaluated using human adherent 3H-TdR-prelabeled HEp-2 epipharynx carcinoma cells as targets at a 50:1 effector-target cell ratio with 25 micrograms concanavalin A/ml in a 24-h assay. Peripheral blood mononuclear cells from 13 patients with cervical carcinoma in stage IV failed to exert cytotoxicity against HEp-2 targets. In contrast, an increased survival (decreased detachment from the monolayer) of HEp-2 cells was observed in the presence of peripheral blood mononuclear cells from patients, this being significantly enhanced by addition of concanavalin A during the lectin-dependent cell-mediated cytotoxicity assay.     

Evaluation of nongenotoxic and genotoxic factors modulating the frequency of micronucleated erythrocytes in the peripheral blood of mice

The hematological micronucleus test is regarded as an indicator of the clastogenic effect of chemicals and acute cytogenetic damage. The test can be carried out in red blood cells of the bone marrow and of the spleen, as well as in peripheral erythrocytes. We have determined the precise background values of micronucleated red blood cells for the peripheral blood of BALB/c, DBA/2, and NMRI mice. Bleeding, phenylhydrazine-induced hemolysis, and splenectomy generated an increase of micronucleated erythrocytes in the peripheral blood of mice. Our data thus demonstrate that such factors should be taken into consideration when the micronucleus test is used for screening the genotoxic potential of chemicals. Furthermore, the micronucleus-inducing effect of cyclophosphamide was studied in normal and splenectomized mice and, in addition, a comparison of the sensitivity of the micronucleus test was carried out in peripheral blood and bone marrow after cyclophosphamide treatment. Our data demonstrate that the kinetics of micronucleus formation were similar in normal and in splenectomized mice in which the micronucleus levels had returned to normal. The comparison of micronucleus formation in bone marrow and peripheral blood after cyclophosphamide treatment revealed the generation of similar quantities of micronucleated red blood cells in both tissues. The physiological mechanisms of micronucleus formation and removal and the potential role of chemically induced spleen damage during this process are discussed; the usefulness of the peripheral micronucleus test as a simple, rapid, and animal-saving modification of the standard bone marrow test is evaluated.Abbreviations CP cyclophosphamide - MN micronuclei - MNCE micronucleated normochromatic erythrocytes - MNPCE micronucleated polychromatic erythrocytes - MNRBC micronucleated red blood cells - NCE normochromatic erythrocytes - PCE polychromatic erythrocytes     

Human peripheral blood mononuclear cells produce IgA anti-influenza virus antibody in a secondary in vitro antibody response

The function and immunoregulation of human IgA memory B cells producing anti-influenza virus antibody was analyzed in vitro in antigen-stimulated cultures. Peripheral blood mononuclear cells (PBMC) from seven of eight normal adult volunteers naturally immunized to influenza virus produced IgA anti-influenza virus antibody when stimulated in vitro with inactivated A/Aichi/68 [H3N2] influenza virus. This IgA antibody response was approximately one-eighth the IgG antibody response. PBMC from each of five patients with selective IgA deficiency failed to produce any measurable IgA antibody. When tonsillar mononuclear cells (TMC) were studied in a similar manner, a relatively higher IgA antibody response was obtained (one-third the IgG antibody) than with PBMC. Additional studies were undertaken to investigate the immunoregulation of this IgA antibody production and the relatively lower amount produced by PBMC than by TMC. Co-cultures of peripheral blood B cells with irradiated peripheral blood T cells (to possibly inactivate a radiosensitive IgA suppressor cell) did not result in a relative increase in IgA antibody production. Also, co-cultures of B cells with increasing numbers of T cells produced parallel increases of IgG and IgA antibody when plotted on a log scale with slopes of approximately 1, suggesting that a single helper T cell was limiting for both isotypes. Finally, pokeweed mitogen-stimulated co-cultures of peripheral blood and tonsillar B and T cells revealed that the B cell population, but not the T cell population, determined the amount of IgA anti-influenza virus antibody produced. Precursor frequency analyses of tonsillar and peripheral blood B cells in antigen-stimulated cultures confirmed that tonsils contained a higher precursor frequency of B cells for IgA anti-influenza virus antibody production (3.95/10(6) B cells) than did peripheral blood B cells (0.65/10(6) B cells). Thus, IgA memory cells are preferentially found in tonsillar tissue as compared with the peripheral blood, consistent with the role of the tonsils as a mucosal immune organ.     

Cellular Reprogramming of Human Peripheral Blood Cells

Breakthroughs in cell fate conversion have made it possible to generate large quantities of patient-specific cells for regenerative medicine. Due to multiple advantages of peripheral blood cells over fibroblasts from skin biopsy, the use of blood mononuclear cells （MNCs） instead of skin fibroblasts will expedite reprogramming research and broaden the application of reprogramming technology. This review discusses current progress and challenges of generating induced pluripotent stem cells （iPSCs） from peripheral blood MNCs and of in vitro and in vivo conversion of blood cells into cells of therapeutic value, such as mesenchymal stem cells, neural cells and hepatocytes. An optimized design of lentiviral vectors is necessary to achieve high reprogramming efficiency of peripheral blood cells. More recently, non-integrating vectors such as Sendai virus and episomal vectors have been successfully employed in generating integration-free iPSCs and somatic stem cells.     

Evaluation of nongenotoxic and genotoxic factors modulating the frequency of micronucleated erythrocytes in the peripheral blood of mice

The hematological micronucleus test is regarded as an indicator of the clastogenic effect of chemicals and acute cytogenetic damage. The test can be carried out in red blood cells of the bone marrow and of the spleen, as well as in peripheral erythrocytes. We have determined the precise background values of micronucleated red blood cells for the peripheral blood of BALB/c DBA/2, and NMRI mice. Bleeding, phenylhydrazine-induced hemolysis, and splenectomy generated an increase of micronucleated erythrocytes in the peripheral blood of mice. Our data thus demonstrate that such factors should be taken into consideration when the micronucleus test is used for screening the genotoxic potential of chemicals. Furthermore, the micronucleus-inducing effect of cyclophosphamide was studied in normal and splenectomized mice and, in addition, a comparison of the sensitivity of the micronucleus test was carried out in peripheral blood and bone marrow after cyclophosphamide treatment. Our data demonstrate that the kinetics of micronucleus formation were similar in normal and in splenectomized mice in which the micronucleus levels had returned to normal. The comparison of micronucleus formation in bone marrow and peripheral blood after cyclophosphamide treatment revealed the generation of similar quantities of micronucleated red blood cells in both tissues. The physiological mechanisms of micronucleus formation and removal and the potential role of chemically induced spleen damage during this process are discussed; the usefulness of the peripheral micronucleus test as a simple, rapid, and animal-saving modification of the standard bone marrow test is evaluated.Abbreviations CP cyclophosphamide - MN micronuclei - MNCE micronucleated normochromatic erythrocytes - MNPCE micronucleated polychromatic erythrocytes - MNRBC micronucleated red blood cells - NCE normochromatic erythrocytes - PCE polychromatic erythrocytes     

Circulating CD34+ hematopoietic progenitors in the harvesting peripheral blood stem cells; enhancement by recombinant human granulocyte colony-stimulating factor

The number of circulating progenitor cells increases during the period of hematopoietic recovery following myeloablative therapy. These progenitor cells were used for autologous transplantation in order to reconstitute hematopoiesis. As an indicator of the circulating progenitor cells, the number of granulocyte-macrophage colony forming units (CFU-GM), which is measured by means of a long-term cell culture, has been widely used. Recently, a cell surface marker, CD34, which can easily be measured by means of flowcytometry, was found to represent immature hematopoietic progenitor cells, which are very close to stem cells. Therefore, the relationship between the number of CD34 positive cells (CD34⁺ cells) and the number of CFU-GM in the peripheral blood following chemotherapy was studied in 9 patients selected to undergo autotransplantation. The number of peripheral blood CD34+ cells was found to be significantly correlated with that of CFU-GM (r = 0.81). When four out of 9 patients received recombinant human granulocyte-colony stimulating factor (rG-CSF) administration, a significant increase in the release of peripheral blood CD34⁺ cells as well as peripheral blood CFU-GM was observed (P<0.01). Thus, the measurement of CD34⁺ cells is useful for predicting the number of circulating CFU-GM.     

Smooth muscle progenitor cells from peripheral blood promote the neovascularization of endothelial colony-forming cells

Proangiogenic cell therapy using autologous progenitors is a promising strategy for treating ischemic disease. Considering that neovascularization is a harmonized cellular process that involves both endothelial cells and vascular smooth muscle cells, peripheral blood-originating endothelial colony-forming cells (ECFCs) and smooth muscle progenitor cells (SMPCs), which are similar to mature endothelial cells and vascular smooth muscle cells, could be attractive cellular candidates to achieve therapeutic neovascularization. We successfully induced populations of two different vascular progenitor cells (ECFCs and SMPCs) from adult peripheral blood. Both progenitor cell types expressed endothelial-specific or smooth muscle-specific genes and markers, respectively. In a protein array focused on angiogenic cytokines, SMPCs demonstrated significantly higher expression of bFGF, EGF, TIMP2, ENA78, and TIMP1 compared to ECFCs. Conditioned medium from SMPCs and co-culture with SMPCs revealed that SMPCs promoted cell proliferation, migration, and the in vitro angiogenesis of ECFCs. Finally, co-transplantation of ECFCs and SMPCs induced robust in vivo neovascularization, as well as improved blood perfusion and tissue repair, in a mouse ischemic hindlimb model. Taken together, we have provided the first evidence of a cell therapy strategy for therapeutic neovascularization using two different types of autologous progenitors (ECFCs and SMPCs) derived from adult peripheral blood.     

A new method for isolation of leukocytes from the peripheral blood of amphibians [Bufo himalayanus, (Gunther)] and study of their surface morphology by scanning electron microscopy

Using percoll as the density gradient, a new single step method to isolate leukocytes from the peripheral blood of amphibians (B. himalayanus) has been described. Isolated leukocytes were photographed under the scanning electron microscope and an attempt has been made to characterize the leukocyte population on the basis of surface morphology. Apart from regular blood cell types, B. himalayanus have slender, elongated and slightly curved leukocyte type cells in their peripheral blood. Such slender elongated cells were absent in the blood of a related species B. stomnaticus and hence could not be categorized under the known blood cell types.     

Peripheral nerve pericytes modify the blood–nerve barrier function and tight junctional molecules through the secretion of various soluble factors

The objectives of this study were to establish pure blood–nerve barrier (BNB) and blood–brain barrier (BBB)‐derived pericyte cell lines of human origin and to investigate their unique properties as barrier‐forming cells. Brain and peripheral nerve pericyte cell lines were established via transfection with retrovirus vectors incorporating human temperature‐sensitive SV40 T antigen (tsA58) and telomerase. These cell lines expressed several pericyte markers such as α‐smooth muscle actin, NG2, platelet‐derived growth factor receptor β, whereas they did not express endothelial cell markers such as vWF and PECAM. In addition, the inulin clearance was significantly lowered in peripheral nerve microvascular endothelial cells (PnMECs) through the up‐regulation of claudin‐5 by soluble factors released from brain or peripheral nerve pericytes. In particular, bFGF secreted from peripheral nerve pericytes strengthened the barrier function of the BNB by increasing the expression of claudin‐5. Peripheral nerve pericytes may regulate the barrier function of the BNB, because the BNB does not contain cells equivalent to astrocytes which regulate the BBB function. Furthermore, these cell lines expressed several neurotrophic factors such as NGF, BDNF, and GDNF. The secretion of these growth factors from peripheral nerve pericytes might facilitate axonal regeneration in peripheral neuropathy. Investigation of the characteristics of peripheral nerve pericytes may provide novel strategies for modifying BNB functions and promoting peripheral nerve regeneration. J. Cell. Physiol. 226: 255–266, 2010. © 2010 Wiley‐Liss, Inc.     

Effect of x-irradiation on amoebocytopoiesis in the snail

The [3H]thymidine radioautography technique was used to study the objective laws of the renewal of blood cells (amoebocytes) of the edible snail (Helix pomatia) after X-radiation. Cells which are the precursors of amoebocytes actively proliferating beyond the limits of peripheral blood have been shown to possess a high radiosensitivity. The action of lethal doses of radiation (200-500 Gr) suppresses their proliferation and leads to the irreversible amoebocytopenia. Radioresistant cells lost the ability to the proliferation circulate in the peripheral blood.