Biomedical subjects

Hajime Sawada

Publications and source records attributed to Hajime Sawada.

13 recordsLinked to original sources

PubMed2005

Use of abdominal wall with mesothelium as a substrate for reconstitution of urinary bladder wall: replacement of the mesothelium by the urothelium and complete bladder wall reconstruction.

OBJECTIVE: The urinary bladder has considerable regenerative ability and may enable reconstitution of the urinary bladder if used appropriately. MATERIAL AND METHODS: Rat urinary bladders were allotransplanted onto the inner surface of the abdominal wall with the urothelium facing the mesothelial cells. The ureters, urethra and blood supply were left intact. RESULTS: A week after the operation, the mesothelium of the abdominal wall was replaced by the urothelium from the donor urinary bladder and a cyst was formed, the inner surfaces of which were completely covered with the urothelium. After a few months, the submucosal tissue and muscular layer had also moved to cover the wall, forming an almost complete urinary bladder. The mucosal membrane formed complex folds, which was probably due to overgrowth of the epithelial cells and the submucosal connective tissues. The area derived from the abdominal wall showed only minimal shrinkage, whereas the abdominal wall from which the mesothelium had been removed showed significant shrinkage. CONCLUSION: This method is potentially useful for the reconstruction of urinary bladders.

Abdominal Wall↗

PubMed2004

Specific induction of neuronal cells from bone marrow stromal cells and application for autologous transplantation.

Bone marrow stromal cells (MSCs) have the capability under specific conditions of differentiating into various cell types such as osteocytes, chondrocytes, and adipocytes. Here we demonstrate a highly efficient and specific induction of cells with neuronal characteristics, without glial differentiation, from both rat and human MSCs using gene transfection with Notch intracellular domain (NICD) and subsequent treatment with bFGF, forskolin, and ciliary neurotrophic factor. MSCs expressed markers related to neural stem cells after transfection with NICD, and subsequent trophic factor administration induced neuronal cells. Some of them showed voltage-gated fast sodium and delayed rectifier potassium currents and action potentials compatible with characteristics of functional neurons. Further treatment of the induced neuronal cells with glial cell line-derived neurotrophic factor (GDNF) increased the proportion of tyrosine hydroxylase-positive and dopamine-producing cells. Transplantation of these GDNF-treated cells showed improvement in apomorphine-induced rotational behavior and adjusting step and paw-reaching tests following intrastriatal implantation in a 6-hydroxy dopamine rat model of Parkinson disease. This study shows that a population of neuronal cells can be specifically generated from MSCs and that induced cells may allow for a neuroreconstructive approach.

Animals↗

PubMed2004

Dynamic changes in intranuclear and subcellular localizations of mouse Prrp/DAZAP1 during spermatogenesis: the necessity of the C-terminal proline-rich region for nuclear import and localization.

Mouse Prrp (mPrrp)/DAZAP1 is a mouse ortholog of Xenopus Prrp, which is involved in vegetal pole localization of Vg1 mRNA in oocytes and is highly expressed in the testis. The mouse protein has been reported to be a shuttling protein which localizes in the nucleus of pre-meiotic spermatogenic cells and round spermatids, and shifts its location into the cytoplasm in elongating spermatids, suggesting that mPrrp may be involved in mRNA transport as well as that of the Xenopus ortholog. We reexamined immunohistochemical analyses of mPrrp/DAZAP1 during spermatogenesis utilizing a newly established monoclonal antibody and reconfirmed it to be a shuttling protein. We also carried out new observations that included remarkable intranuclear movement during spermatogenesis. In addition, we found that a long amino acid stretch which spanned over the C-terminal half of the protein was required for the nuclear import. These observations demonstrated dynamic changes in subnuclear and subcellular localization which might reflect specific functions during spermatogenesis.

Active Transport, Cell Nucleus↗

PubMed2004

Peripheral nerve regeneration by transplantation of bone marrow stromal cell-derived Schwann cells in adult rats.

OBJECT: Bone marrow stromal cells (BMSCs) can be induced to form Schwann cells by sequentially treating the cells with beta-mercaptoethanol and retinoic acid, followed by forskolin and neurotrophic factors including heregulin. In this study the authors made artificial grafts filled with BMSC-derived Schwann cells (BMSC-DSCs) and transplanted them into the transected sciatic nerve in adult rats to evaluate the potential of BMSCs as a novel alternative method of peripheral nerve regeneration. METHODS: The BMSC-DSCs were suspended in Matrigel and transferred into hollow fibers (12 mm in length), which were transplanted into the transected sciatic nerve in adult Wistar rats. Six months after cell transplantation, electrophysiological evaluation and walking track analysis were performed. Results of these studies showed significant improvement in motor nerve conduction velocity and sciatic nerve functional index in the BMSC-DSC-transplanted group compared with the control group (Matrigel graft only). Immunohistochemical study data demonstrated that transplanted BMSCs labeled with retrovirus green fluorescent protein were positive for P0 and myelin-associated glycoprotein and had reconstructed nodes of Ranvier and remyelinated regenerated nerve axons. The number of regenerated axons in the axial section of the central portion of the graft was significantly greater in the transplanted group. Although BMSCs can differentiate into several types of cells, tumor formation did not occur 6 months after engraftment. CONCLUSIONS: Results in this study indicate that BMSC-DSCs have great potential to promote regeneration of peripheral nerves. The artificial graft made with BMSC-DSCs represents an alternative method for the difficult reconstruction of a long distance gap in a peripheral nerve.

Animals↗

PubMed2003

Increment of murine spermatogonial cell number by gonadotropin-releasing hormone analogue is independent of stem cell factor c-kit signal.

Recent studies have demonstrated that GnRH-analogues can stimulate regeneration of spermatogenesis of rats when administered after testicular damages. Although the mechanism of this phenomenon has not been elucidated yet, stem cell factor (SCF) produced by Sertoli cells was proposed to mediate the effects of GnRH-analogues on spermatogonial proliferation and/or survival. In the present study, we quantitatively evaluated the proliferation of spermatogonia and addressed whether SCF mediates the effect of GnRH-analogue on spermatogonial proliferation, using a novel approach combining spermatogonial transplantation and laser confocal microscopic observation. In the first experiment, using wild-type mice as recipients for spermatogonial transplantation, the number of donor spermatogonia per 100 Sertoli cells in each spermatogenic colony was significantly higher in the experimental group of mice treated with leuprorelin, a GnRH-agonist, than that of the control group at 4 and 5 wk after transplantation. In the second experiment, Steel/Steeldickie (Sl/Sld) mutant mice, which lack expression of membrane bound form SCF, were used as recipients. As seen in the first experiment, the number of undifferentiated spermatogonia was significantly higher in leuprorelin-treated than in the control group. Since undifferentiated spermatogonia do not express the receptor of SCF, the present study clearly demonstrates that neither membrane-bound nor secreted forms of SCF are involved in the mechanism of GnRH-analogue's effect on spermatogonial proliferation and/or survival.

Animals↗

PubMed2003

Transfer of the von Hippel-Lindau gene to neuronal progenitor cells in treatment for Parkinson's disease.

Neuronal progenitor cells (NPCs) may provide dopaminergic neurons for the treatment of Parkinson's disease (PD). However, transplantation of NPCs into the striatum by current methods has had limited success. It is possible to reverse the symptoms of PD in model rats but difficult to reverse them in humans because the number of dopaminergic neurons generated from NPCs is low. We transduced the von Hippel-Lindau (VHL) gene into NPCs isolated from embryonic rat brain. The NPCs with the transduced VHL gene efficiently differentiated into tyrosine hydroxylase-positive neurons in vitro. NPCs with the transduced VHL gene, which were labeled in advance with bromodeoxyuridine, were transplanted into the striatum of a rat model of PD. Numerous bromodeoxyuridine-tyrosine hydroxylase double-labeled cells were seen close to the transplant site, showing that the transplanted cells efficiently generated new dopaminergic neurons within the host striatum. Moreover, all of the animals with NPCs with VHL showed a remarkable decrease in apomorphine-induced rotations. These findings show that NPCs with the VHL gene can efficiently generate dopaminergic neurons and that a sufficient number of dopaminergic neurons can develop from them to reverse the symptoms of PD in humans. VHL gene transduction provides a new therapeutic approach for treatment of PD.

Animals↗

PubMed2003

Electron microscopic observation of 137Cs-irradiated rat testis: production of basal laminae for germ cells, despite their absence.

Whole body gamma-ray irradiation of rats with caesium-137 (137Cs) at embryonic day 20 induced marked reduction of the weight of the testis. Body weight and other tissues, however, seemed to remain normal. By light microscopy, complete loss of germ cells was observed in the testis. Other components, such as Sertoli cells and interstitial cells, seemed to be normal. The testes from day 8 postpartum rats contained very few spermatogonia compared with newborn rats, indicating loss of germ cells between days 0 and 8. In the adult, 137Cs-irradiated testes showed two conspicuous features other than the loss of germ cells: empty vacuolar spaces between Sertoli cells and multilayered seminiferous tubule basal laminae (lamina densa). The junctional structures (ectoplasmic specializations) between Sertoli cells, however, seemed normal. The thickness of each layer of multilayered basal laminae was the same as that of normal rats and electron-lucent layers similar to lamina lucida were interposed between them. Of the empty vacuolar spaces between Sertoli cells, basal laminae bridge the gap. The basal laminae contained laminin, type IV collagen and heparan sulphate proteoglycan evenly distributed among layers, suggesting a normal composition. Rough estimation of the amount of basal laminae deposited in 137Cs-irradiated rats indicates that it is within a range similar to that in normal testis. These features imply that Sertoli cells are, in part, determined perinatally to produce basal laminae for germ-line cells.

Animals↗

PubMed2003

Expansion of murine spermatogonial stem cells through serial transplantation.

Mammalian male germ cells might be generally thought to have infinite proliferative potential based on their life-long production of huge numbers of sperm. However, there has been little substantial evidence that supports this assumption. In the present study, we performed serial transplantation of spermatogonial stem cells to investigate if they expand by self-renewing division following transplantation. The transgenic mouse carrying the Green fluorescent protein gene was used as the donor cell source that facilitated identification and recollection of colonized donor germ cells in the recipient testes. The established colonies of germ cells in the recipient testes were collected and transplanted to new recipients. This serial transplantation of spermatogonial stem cells repopulated the recipient testes, which were successfully performed sequentially up to four times from one recipient to the next. The incubation periods between two sequential transplantations ranged from 55 to 373 days. During these passages, the spermatogonial stem cells showed constant activity to form spermatogenic colonies in the recipient testis. They continued to increase in number for more than a year following transplantation. Colonization efficiency of spermatogonial stem cells was determined to be 4.25% by using Sl/Sl(d) mice as recipients that propagated only undifferentiated type A spermatogonia in their testes. Based on the colonization efficiency, one colony-forming activity was assessed to equate to about 20 spermatogonial stem cells. The spermatogonial stem cells were estimated to expand over 50-fold in 100 days in this experiment.

Animals↗

PubMed2002

Brain-derived neurotrophic factor enhances neurite regeneration from retinal ganglion cells in aged human retina in vitro.

To investigate the capability of neurite regeneration from retinal ganglion cells (RGCs) in an adult human retina and to evaluate the effect of neurotrophin on the neurite regeneration, an in vitro model for retinal explants was developed. A human retina was obtained from a 70 year old patient with retrobulbar carcinoma. The retina was excised and the retinal explants were cultured in serum-free medium with or without brain-derived neurotrophic factor. The capability of neurite regeneration was evaluated by counting the numbers of outgrowing neurites outside the retinal explants. In culture without brain-derived neurotrophic factor (control), there was no neurite outgrowth from the retinal explants after 2 days. And at 3 days in culture, a small number of outgrowing neurites were first observed outside the retinal explants. In contrast, within 24 hr in culture with brain-derived neurotrophic factor, there were a considerable number of elongating neurites with spread growth cones from the retinal explants. Immunohistochemical analysis revealed that these neurites were derived from RGCs. The addition of brain-derived neurotrophic factor increased the number of outgrowing neurites approximately 10-fold compared to that of the control at 3 days in culture. The enhancement of neurite regeneration induced by brain-derived neurotrophic factor continued for longer than 1 week in culture. In conclusion, an aged human retina can regenerate neurites from RGCs in vitro and brain-derived neurotrophic factor significantly promotes the regeneration.

Aged↗

PubMed2002

Bilateral persistent sciatic arteries in a Japanese man.

During student dissecting practice, a rare developmental anomaly showing persistent sciatic artery (PSA) was found in the bilateral lower limbs of a 74-year-old Japanese male cadaver. The PSA was a continuation of the internal iliac artery on both sides, did not anastomose with the perforating arteries and ended by anastomosing with the popliteal artery on both sides. The course and distribution of the PSA were relatively consistent with previous reports. In the present case, however, the PSA and inferior gluteal arteries existed simultaneously on both sides, despite the general assumption that the inferior gluteal artery is a remnant of sciatic artery regression.

Aged↗

PubMed2002

Preservation of retinal morphology and functions in royal college surgeons rat by nilvadipine, a Ca(2+) antagonist.

PURPOSE: The Royal College of Surgeons (RCS) rat is the most extensively studied animal model for understanding the molecular pathology in inherited retinal degeneration, such as retinitis pigmentosa (RP). The purpose of the present study was to evaluate the pharmacologic effects of several Ca(2+) antagonists on the retinal degeneration of RCS rats. METHODS: Several Ca(2+) antagonists, diltiazem, nicardipine, nilvadipine, and nifedipine, were intraperitoneally administered and retinal morphology and functions analyzed. RESULTS: Among the Ca(2+) antagonists, only intraperitoneally administered nilvadipine preserved retinal morphology and electroretinogram responses in RCS rats during the initial stage of retinal degeneration. Studies using immunohistochemistry, RT-PCR, and Western blot analysis revealed significant enhancement of rhodopsin kinase and alphaA-crystallin expression and suppression of caspase 1 and 2 expression in the retina of nilvadipine-treated rats. CONCLUSIONS: These data suggest that nilvadipine is beneficial for the preservation of photoreceptor cells in RCS rats and can be used to treat some patients with RP.

Animals↗

PubMed2002

The role of c-fos in cell death and regeneration of retinal ganglion cells.

PURPOSE: To investigate the effect of c-fos on apoptotic cell death and regeneration of damaged retinal ganglion cells (RGCs) in tissue culture of retinal explants. METHODS: Retinas from transgenic mice carrying the exogenous c-fos gene under the control of the interferon (IFN)-alpha/beta inducible Mx-promoter (Mx-c-fos), c-fos-deficient mice, and littermate control mice were dissected and cultured in a three-dimensional collagen gel culture system, followed by an analysis of TdT-dUTP terminal nick-end labeling (TUNEL) staining and measurement of neurites that emerged from explants. RESULTS: Compared with littermate control mice, Mx-c-fos transgenic animals showed a higher ratio of TUNEL positivity in the RGC layer from early in the culture period that correlated with the small number of regenerating neurites. In contrast, the c-fos-null mutated mice showed a still-lower ratio of TUNEL-positive cells. Nevertheless, the number of regenerating neurites was significantly lower in the initial phase, although the drastic increase in density of neurite regeneration was observed in the late period of culture. CONCLUSIONS: These findings suggest that c-fos is involved in both apoptotic cell death and regeneration of damaged RGCs. Elucidation of the precise c-fos-mediated cascade involved in RGC apoptosis and regeneration is significant in realizing neuronal survival and regeneration.

Animals↗

PubMedDate not supplied

Transplantation of the urinary bladder and other organs in the subcutaneous tissue induces cyst formation and epithelialization: its potential usefulness in regenerative medicine.

Certain hollow organs are known to form cysts when heterologously transplanted. In order to examine the usefulness of the phenomenon for regenerative medicine, rat urinary bladders and other organs were allo-transplanted under the subcutaneous tissue of the back. These transplanted tissues very often formed cysts covered with epithelia. The epithelia covered an area about twice the original size. In the case of the urinary bladder, the epithelium started moving from the edge of the transplants around day 3 after the operation, and as time proceeded, the tela submucosa and tunica muscularis also moved to encircle the epithelium, and formed the wall of the cyst. The basal laminae were formed under the newly expanded epithelium slightly behind the leading tip. All of the organs tested had the capability of cyst formation and epithelialization, although their rate differed between organs. The results are discussed with reference to the potential use of cyst formation for regenerating damaged organs.

Animals↗