Kohei Johkura

Intracellular targeting therapy of cisplatin-encapsulated transferrin-polyethylene glycol liposome on peritoneal dissemination of gastric cancer

Peritoneal dissemination in gastric cancer is a common fatal clinical condition with few effective therapies available. We studied the therapeutic effect of a tumor‐targeting drug delivery system that uses cisplatin‐encapsulated and Tf‐conjugated PEG liposomes (Tf‐PEG liposomes) in nude mice with peritoneal dissemination of human gastric cancer cells. Small unilamellar Tf‐PEG, PEG or DSPC/CH liposomes (bare liposomes) encapsulating cisplatin were prepared by reverse‐phase evaporation followed by extrusion. Electron microscopic studies revealed that Tf‐PEG liposomes were internalized into tumor cells by receptor‐mediated endocytosis. To examine the biodistribution of each liposome and cisplatin level, nude mice were inoculated i.p. with 107 MKN45P human gastric tumor cells. On the fourth day after tumor inoculation, 3H‐CHE‐labeled and cisplatin‐encapsulated Tf‐PEG, PEG or bare liposome were inoculated i.p. The Tf‐PEG liposome–administered group maintained high liposome and cisplatin levels in ascites and showed a prolonged residence time in the peripheral circulation. Uptake of Tf‐PEG liposomes into the liver and spleen was significantly lower than that of bare liposomes. Uptake of Tf‐PEG liposomes in disseminated tumor cells of ascites and the greater omentum was significantly higher than that of PEG or bare liposomes and a significant increase in cisplatin levels was observed in these tumor cells. Mice receiving Tf‐PEG liposomes 1 and 4 days after the day of tumor inoculation showed significantly higher survival rates compared with those receiving PEG liposomes without Tf, bare liposomes or free cisplatin solution. These results suggest that cisplatin‐encapsulated Tf‐PEG liposomes may be useful as a new intracellular targeting carrier for treatment of gastric cancer with peritoneal dissemination.

FAK promotes organization of fibronectin matrix and fibrillar adhesions

Targeted disruption of the focal adhesion kinase (FAK) gene in mice is lethal at embryonic day 8.5 (E8.5). Vascular defects in FAK-/- mice result from the inability of FAK-deficient endothelial cells to organize themselves into vascular network. We found that, although fibronectin (FN) levels were similar, its organization was less fibrillar in both FAK-/- endothelial cells and mesoderm of E8.5 FAK-/- embryos, as well as in mouse embryonic fibroblasts isolated from mutant embryos. FAK catalytic activity, proline-rich domains, and location in focal contacts were all required for proper allocation and patterning of FN matrix. Cells lacking FAK in focal adhesions fail to translocate supramolecular complexes of integrin-bound FN and focal adhesion proteins along actin filaments to form mature fibrillar adhesions. Taken together, our data suggest that proper FN allocation and organization are dependent on FAK-mediated remodeling of focal adhesions.

Spatial distribution and initial changes of SSEA-1 and other cell adhesion-related molecules on mouse embryonic stem cells before and during differentiation.

We examined the distribution of cell adhesion-related molecules (CAMs) among mouse embryonic stem (ES) cells and the spatial distribution on cell surfaces before and during differentiation. The cell-cell heterogeneity of SSEA-1, PECAM-1, and ICAM-1 among the undifferentiated cells in the ES cell colonies was evident by immunohistochemistry and immuno-SEM, supporting the flow cytometry findings. In contrast, most undifferentiated ES cells strongly expressed CD9. SSEA-1 was located preferentially on the edge of low protuberances and microvilli and formed clusters or linear arrays of 3–20 particles. PECAM-1 and ICAM-1 were randomly localized on the free cell surfaces, whereas CD9 was preferentially localized on the microvilli or protuberances, especially in the cell periphery. Both the SSEA-1+ fraction and the SSEA-1− fraction of magnetic cell sorting (MACS) formed undifferentiated colonies after plating. Flow cytometry showed that these populations reverted separately again to a culture with a mixed phenotype. Differentiation induced by retinoic acid downregulated the expression of all CAMs. Immuno-SEM showed decreases of SSEA-1 in the differentiated ES cells, although some clustering still remained. Our findings help to elucidate the significance of these molecules in ES cell maintenance and differentiation and suggest that cell surface antigens may be useful for defining the phenotype of undifferentiated and differentiated ES cells.

Bone morphogenetic protein-4 promotes induction of cardiomyocytes from human embryonic stem cells in serum-based embryoid body development

Cardiomyocytes derived from human embryonic stem (ES) cells are a potential source for cell-based therapy for heart diseases. We studied the effect of bone morphogenetic protein (BMP)-4 in the presence of fetal bovine serum (FBS) on cardiac induction from human H1 ES cells during embryoid body (EB) development. Suspension culture for 4 days with 20% FBS produced the best results for the differentiation of early mesoderm and cardiomyocytes. The addition of Noggin reduced the incidence of beating EBs from 23.6% to 5.3%, which indicated the involvement of BMP signaling in the spontaneous cardiac differentiation. In this condition, treatment with 12.5-25 ng/ml BMP-4 during the 4-day suspension optimally promoted the cardiomyocyte differentiation. The incidence of beating EBs at 25 ng/ml BMP-4 reached 95.8% on day 6 of expansion and then plateaued until day 20. In real-time PCR analysis, the cardiac development-related genes MESP1 and Nkx2.5 were upregulated in the EB outgrowths by 25 ng/ml BMP-4. The activation of BMP signaling in EBs was confirmed by the increase in the phosphorylation of Smad1/5/8 and by the nuclear localization of phospho-Smad1/5/8 and Smad4. The addition of 150 ng/ml Noggin considerably decreased the incidence of beating EBs and Nkx2.5 expression, and Noggin alone increased Nestin expression and neural differentiation in EB outgrowths. The cardiomyocytes induced by 25 ng/ml BMP-4 showed proper cell biological characteristics and a course of differentiation as judged from isoproterenol administration, gene expression, protein assay, immunoreactivity, and subcellular structures. No remarkable change in the extent of apoptosis and proliferation in the cardiomyocytes was observed by BMP-4 treatment. These findings showed that BMP-4 in combination with FBS at the appropriate time and concentrations significantly promotes cardiomyocyte induction from human ES cells.

Staged in vitro reconstitution and implantation of engineered rat kidney tissue

A major hurdle for current xenogenic-based and other approaches aimed at engineering kidney tissues is reproducing the complex three-dimensional structure of the kidney. Here, a stepwise, in vitro method of engineering rat kidney-like tissue capable of being implanted is described. Based on the fact that the stages of kidney development are separable into in vitro modules, an approach was devised that sequentially induces an epithelial tubule (the Wolffian duct) to undergo in vitro budding, followed by branching of a single isolated bud and its recombination with metanephric mesenchyme. Implantation of the recombined tissue results in apparent early vascularization. Thus, in principle, an unbranched epithelial tubular structure (potentially constructed from cultured cells) can be induced to form kidney tissue such that this in vitro engineered tissue is capable of being implanted in host rats and developing glomeruli with evidence of early vascularization. Optimization studies (of growth factor and matrix) indicate multiple suitable combinations and suggest both a most robust and a minimal system. A whole-genome microarray analysis suggested that recombined tissue recapitulated gene expression changes that occur in vivo during later stages of kidney development, and a functional assay demonstrated that the recombined tissue was capable of transport characteristic of the differentiating nephron. The approach includes several points where tissue can be propagated. The data also show how functional, 3D kidney tissue can assemble by means of interactions of independent modules separable in vitro, potentially facilitating systems-level analyses of kidney development.

Titanium oxide nanotubes for bone regeneration

Titanium oxide nanotubes with Ca ions on their surfaces were prepared as 2 mm cylindrical inserts and placed into surgically created bone defects in the femurs of Wistar rats. On day 3, fibroblast-like cells were present on the surface of the nanotube inserts and fibers were observed by scanning electron microscopy (SEM). On day 7, cells with alkaline phosphatase activity were present and identified as osteoblasts by SEM and transmission electron microscopy. New bone matrices were observed in and around the porous nanotube inserts by light microscopy. Compared with clinically used hydroxyapatite and tricalcium phosphate, β-titanium oxide nanotubes promote faster acquisition and development of osteoblasts and bone tissues and have better bone regenerating ability after one week.

Induction of midbrain dopaminergic neurons from primate embryonic stem cells by coculture with sertoli cells

The aim of this study was to produce dopaminergic neurons from primate embryonic stem (ES) cells following coculture with mouse Sertoli cells. After 3 weeks of induction, immunostaining revealed that 90% ± 9% of the colonies contained tyrosine hydroxylase‐positive (TH+) neurons, and 60% ± 7% of the tubulin β III‐positive (Tuj III+) neurons were TH+. Reverse transcription‐polymerase chain reaction analyses showed that Sertoli‐induced neurons expressed midbrain dopaminergic neuron markers, including TH, dopamine transporter, aromatic amino acid decarboxylase (AADC), receptors such as TrkB and TrkC, and transcription factors NurrI and Lmx1b. Neurons that had been differentiated on Sertoli cells were positive for Pax2, En1, and AADC, midbrain‐related markers, and negative for dopamine‐β‐hydroxylase, a marker of noradrenergic neurons. These Sertoli cell‐induced dopaminergic cells can release dopamine when depolarized by high K+. Sertoli cell‐conditioned medium contained glial cell line‐derived neurotrophic factor (GDNF) and supported neuronal differentiation. After pretreatment with anti‐GDNF antibody, the percentage of Tuj III+ colonies was reduced to 14%. Thus, GDNF contributed significantly to inducing primate ES cells into dopaminergic neurons. When transplanted into a 6‐hydroxydopamine‐treated Parkinsons disease model, primate‐derived dopaminergic neurons integrated into the mouse striatum. Two weeks after transplantation, surviving TH+ cells were present. These TH+ cells survived for 2 months. Therefore, the induction method of coculture ES cells with Sertoli cells provides an unlimited source of primate cells for the study of pathogenesis and transplantation in Parkinsons disease.

Survival and function of mouse embryonic stem cell-derived cardiomyocytes in ectopic transplants

OBJECTIVE Embryonic stem cell-derived cardiomyocytes are a useful source for cell transplantation into the heart, as well as for tissue engineering of the extracardiac vascular system. The present study was designed to investigate the survival and contractile function of embryonic stem cell-derived cardiomyocytes around large blood vessels to assess the feasibility of their ectopic use for future engineering of cardiovascular tissues. METHODS The mouse embryonic stem cell-derived cardiomyocytes were transplanted into the retroperitoneum of the adult nude mice, and the myocardial tissues that developed were characterized by electrophysiological and histological techniques. RESULTS Macroscopic and electrophysiological analyses showed spontaneously contracting transplants in the host retroperitoneum 7 and 30 days after transplantation. Immunohistochemistry detected developing cardiomyocytes in the transplants on Day 7, which formed the myocardial tissues. They were positive for cardiac troponin I, cadherin, connexin 43, and proliferating cell nuclear antigen, but negative for alpha-smooth muscle actin. Vascular formation was discernible in the transplant tissues. By Day 30, more mature myocardial tissues had been established in the transplants. Electron microscopic study emphasized that the transplant tissues comprised cardiomyocytes, in which myofibrils with organized sarcomeres were observed. Desmosomes, fasciae adherens and gap junctions were evident in the cellular junctions. CONCLUSIONS The cardiomyocytes derived from the mouse ES cells were demonstrated to be viable and function in the ectopic site of the host retroperitoneum up to Day 30, following a process of proliferation and differentiation. Vascularization and host perfusion beneficial for the survival of the cardiomyocytes occurred in the transplants.

A key inactivation factor of HeLa cell viability by a plasma flow

Recently, a plasma flow has been applied to medical treatment using effects of various kinds of stimuli such as chemical species, charged particles, heat, light, shock wave and electric fields. Among them, the chemical species are known to cause an inactivation of cell viability. However, the mechanisms and key factors of this event are not yet clear. In this study, we focused on the effect of H2O2 in plasma-treated culture medium because it is generated in the culture medium and it is also chemically stable compared with free radicals generated by the plasma flow. To elucidate the significance of H2O2, we assessed the differences in the effects of plasma-treated medium and H2O2-added medium against inactivation of HeLa cell viability. These two media showed comparable effects on HeLa cells in terms of the survival ratios, morphological features of damage processes, permeations of H2O2 into the cells, response to H2O2 decomposition by catalase and comprehensive gene expression. The results supported that among chemical species generated in a plasma-treated culture medium, H2O2 is one of the main factors responsible for inactivation of HeLa cell viability.

Biodefense function of omental milky spots through cell adhesion molecules and leukocyte proliferation.

Abstract. To evaluate the immunological functions of the greater omentum in the peritoneal cavity, the localization of cell adhesion molecules (CAMs) on mesothelial cells and leukocytes in the omental milky spots were studied in normal and lipopolysaccharide (LPS)-stimulated mice by means of immunoelectron microscopy. The milky spots featured numerous leukocytes among the dome-shaped mesothelial cells, even in the normal stable state. Leukocyte integrins LFA-1, Mac-1, and VLA-4 were preferentially localized to microvilli and ruffles of macrophages and lymphocytes. The mesothelial cells of the milky spots showed higher ICAM-1 levels than did those of other omental regions, and fibronectin was detected in the stomata. The number of leukocytes markedly increased following an increase in proliferating cell nuclear antigen (PCNA)-positive cells in the milky spots after LPS stimulation. The mesothelial cells contained VCAM-1 newly restricted to the microvilli and increasing amounts of ICAM-1. These results show that the omental milky spots are active sites for leukocyte migration and peritoneal leukocyte supply because of the presence of adhesion molecules and active cell proliferation. Proliferative active leukocytes and those that have migrated from vessels pass through the stomata via an interaction of VLA-4 and fibronectin, adhere to the microvilli of the activated mesothelial cell surface as the result of an interaction between ICAM-1/VCAM-1 and integrins, and exude into the peritoneal cavity. Much of the exudation and adhesion of leukocytes seen in the milky spots of LPS-stimulated mice may be attributable to an increase in cell proliferation and in the amounts of ICAM-1 and VCAM-1.