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Yasuhiko Tabata

Publications and source records attributed to Yasuhiko Tabata.

At least 145 records · Page 8Linked to original sources
PubMed2003

Local delivery of matrix metalloproteinase gene prevents the onset of renal sclerosis in streptozotocin-induced diabetic mice.

The present study was undertaken to investigate whether matrix metalloproteinase (MMP) functions to prevent the occurrence of destructive fibrosis in progressive renal disease. As a sustained release carrier of plasmid DNA, biodegradable hydrogels and microspheres were formulated from cationized gelatin prepared through aminization. Plasmid DNA was released from the cationized gelatin hydrogels as a result of hydrogel degradation. A plasmid DNA including a cytomegalovirus promoter and human recombinant MMP-1 gene (pCMV-MMP) was constructed. Gelatin microspheres incorporating pCMV-MMP as well as phosphate-buffered saline (PBS) with or without pCMV-MMP were injected into the renal subcapsule of C57BL/6 mice, which were intraperitoneally injected with streptozotocin (STZ) to induce diabetes 7 days after operation. The mice were killed 4 weeks after STZ injection to sample their blood and kidneys for biochemical and histological examinations. An immunofluorescence study confirmed that MMP protein was expressed around the renal tissue injected with gelatin microspheres incorporating pCMV-MMP. When applied with cationized gelatin microspheres incorporating pCMV-MMP, the mice showed a level of blood urea nitrogen significantly lower than that of other groups. A reduced content of collagen in the kidneys of mice administered gelatin microspheres incorporating pCMV-MMP was histologically observed. Further, the hydroxyproline assay revealed a significantly decreased content of hydroxyproline in kidney. We conclude that sustained release of MMP-1 gene is a promising prophylactic trial for kidney fibrolysis and dysfunction in the STZ-induced diabetic mouse model.

Animals↗
PubMed2003

Novel approach to regeneration of periodontal tissues based on in situ tissue engineering: effects of controlled release of basic fibroblast growth factor from a sandwich membrane.

To regenerate periodontal tissues, a sandwich membrane composed of a collagen sponge scaffold and gelatin microspheres containing basic fibroblast growth factor (bFGF) in a controlled-release system was developed according to the new concept of "in situ tissue engineering." A three-walled alveolar bone defect (3 x 4 x 4 mm) was made bilaterally in edentulous regions created mesially to the canines in both the maxilla and mandible of nine beagle dogs. A sandwich membrane with or without bFGF (100 microg) was implanted in each defect (each group, n = 18). During weeks 1, 2, and 4, histologic evaluation and histometric analyses were performed on three dogs. Throughout the 4 weeks, vascularization and osteogenesis were active only in the bFGF-treated group (p < 0.01). New cementum was formed (2.4 +/- 0.9 mm) on the exposed root surface at 4 weeks, and functional recovery of the periodontal ligament was indicated in part by the perpendicular orientation of regenerated collagen fibers. In the control group, epithelial downgrowth and root resorption occurred and the defects were filled with connective tissue. Thus, our sandwich membrane induced successful regeneration of the periodontal tissues in a short period of time.

Animals↗
PubMed2003

Bioartificial pancreas transplantation at prevascularized intermuscular space: effect of angiogenesis induction on islet survival.

INTRODUCTION: Bioartificial pancreas (BAP) transplantation offers a potential treatment of diabetes mellitus. The optimal site for BAP transplantation has not yet been established. AIM: To monitor the effect of induction of neovascularization at the intermuscular space on islet survival after allogenic transplantation of BAP. METHODOLOGY: Angiogenesis was induced at the intermuscular space of diabetic Lewis rats by implanting a polyethylene terephthalate (PET) mesh bag, which enclosed a collagen sponge and biodegradable gelatin microspheres containing basic fibroblast growth factor. After confirmation of angiogenesis, BAP was prepared by mixing of 5% agarose with approximately 2,800 isolated rat (Sprague-Dawley) islets and transplanted into the prevascularized PET mesh bag. RESULTS: Neovascularization was observed in and around the PET mesh bag within 10 days after implantation as confirmed by macroscopic and microscopic examinations. In the presence of a collagen sponge, new blood vessels penetrated into the PET mesh bag and formed a vascular bed. After transplantation, normoglycemia was achieved in the rats within 3 days and maintained for >35 days. The rats gradually gained body weight, and the results of intravenous glucose tolerance test showed normal patterns of blood glucose clearance 1 month after transplantation. CONCLUSION: It can be concluded that the prevascularized PET mesh bag enabled transplanted BAP to survive and maintain function, thus indicating a potential site for BAP transplantation.

Animals↗
PubMed2003

Bioengineered implantation of megalin-expressing cells: a potential intracorporeal therapeutic model for uremic toxin protein clearance in renal failure.

Patients who have renal failure and are on dialysis therapy experience serious complications caused by low-molecular-weight uremic toxin proteins normally filtered by glomeruli and metabolized by proximal tubule cells (PTC). Dialysis-related amyloidosis is one such complication induced by systemic deposition of amyloid proteins derived from 12-kD beta(2)-microglobulin (beta(2)-m). Despite the use of high-flux membrane hemodialysis devices and direct absorbent columns, the removal of beta(2)-m is suboptimal, because the effects are transient and insufficient. Megalin is expressed in the apical membranes of PTC and recognized as a multiligand endocytic receptor that binds numerous low-molecular-weight proteins, including beta(2)-m. This study tested the feasibility of an intracorporeal therapeutic model of continuous beta(2)-m removal using megalin-expressing cell implantation. By cell association and degradation assays, rat yolk sac-derived L2 cells were identified to internalize and degrade beta(2)-m via megalin. The cells were effectively implanted within the subcutaneous tissues of nude mice using a type I collagen scaffold and a method inducing local angiogenesis. After nephrectomy and intraperitoneal injection with (125)I-beta(2)-m, it was found that the implanted cells took up the labeled ligand, efficiently removing it from the blood. Bioengineered implantation of megalin-expressing cells may represent a new supportive therapy for dialysis patients to compensate for the loss of renal protein metabolism and remove uremic toxin proteins.

Animals↗
PubMed2003

Bladder regeneration by bladder acellular matrix combined with sustained release of exogenous growth factor.

PURPOSE: We investigate the use of bladder acellular matrix (BAM) as a carrier of exogenous growth factor. MATERIALS AND METHODS: Basic fibroblast growth factor (bFGF) protein was loaded in a lyophilized BAM by rehydrating the matrix with the growth factor solution. In vitro and in vivo release of bFGF from BAM was traced by radiolabeled bFGF. To assess biological effect of the released bFGF, BAMs incorporating bFGF were implanted into back subcutis of mice and vascular endothelial growth factor levels in the local tissue were determined. Furthermore, bladder augmentation was performed in rats with BAM grafts containing various concentrations of bFGF. At 4 and 12 weeks the graft size at maximal cystometric capacity was evaluated, followed by histological and physiological evaluation. RESULTS: Sustained release of bFGF from BAM was observed in vitro and in vivo. In vivo biological activity of bFGF in BAM as determined by vascular endothelial growth factor levels was preserved for more than 3 weeks. In the bladder augmentation model angiogenesis into the matrix was promoted and graft shrinkage was significantly inhibited by incorporated bFGF in a dose dependent manner at 4 weeks. CONCLUSIONS: BAM can function as a platform for sustained release of exogenous bFGF. This delivery method of growth factor could be a useful tool for bladder reconstruction.

Animals↗
PubMed2003

Acceleration of aneurysm healing by controlled release of basic fibroblast growth factor with the use of polyethylene terephthalate fiber coils coated with gelatin hydrogel.

OBJECTIVE: The aims of this study were to develop an endovascular delivery system containing gelatin hydrogels for the controlled release of basic fibroblast growth factor (bFGF) with the use of polyethylene terephthalate fiber coils and to analyze whether such a system would promote healing in an experimental aneurysm. METHODS: Carotid aneurysms were constructed in 66 rabbits with venous pouches. The polyethylene terephthalate fiber coils coated with and without gelatin hydrogels with different water volumes containing 0, 10, 50, and 100 microg bFGF were implanted into the aneurysms. Histological specimens were harvested at 1, 2, and 3 weeks and at 6 months after implantation. A histological evaluation was performed while the area occupied by the fibrosis in the aneurysms was calculated. RESULTS: Three weeks after the application of the coils coated with gelatin hydrogels (95 vol%) containing 100 microg bFGF, all aneurysmal orifices were completely closed with neointima. When the coils coated with gelatin hydrogel (98 vol%) containing 100 microg bFGF were used, the orifices in three of the six aneurysms were closed. In contrast, the orifice of the aneurysm was not obliterated when other materials were used. After implanting the coils coated with gelatin hydrogel (95 vol%) containing 100 microg bFGF more than 3 weeks later, the aneurysm was histologically suffused with fibrous tissue, and the area occupied by fibrosis was significantly larger than that observed in the other groups (P < 0.05). CONCLUSION: Local, controlled release of sufficient amounts of bFGF with polyethylene terephthalate fiber coils coated with gelatin hydrogel accelerated the organization of aneurysms.

Aneurysm↗
PubMed2003

Ultrasound enhances the transfection of plasmid DNA by non-viral vectors.

Increasing attention has been paid to technology used for the delivery of genetic materials into cells for gene therapy and the generation of genetically engineered cells. So far, viral vectors have been mainly used because of their inherently high transfection efficiency of gene. However, there are some problems to be resolved for the clinical applications, such as the pathogenicity and immunogenicity of viral vectors themselves. Therefore, many research trials with non-viral vectors have been performed to enhance their efficiency to a level comparable to the viral vector. Two directions of these trials exist: material improvement of non-viral vectors and their combination with various external physical stimuli. This paper reviews the latter research trials, with special attention paid to the enhancement of gene expression by ultrasound (US). The expression level of plasmid DNA by various cationized polymers and liposomes is promoted by US irradiation in vitro as well as in vivo. This US-enhanced expression of plasmid DNA will be discussed to emphasize the technical feasibility of US in gene therapy and biotechnology.

Animals↗
PubMed2003

The development of new immunoisolatory devices possessing the ability to induce neovascularization.

The transplantation of a bioartificial pancreas has been regarded as a potential method for successful islet transplantation without any immunosuppressive agents. The subcutaneous site is a very attractive site for transplantation of a bioartificial pancreas because of its advantage of an easy operation site. Our group has been reporting that transplantation of a bioartificial pancreas to the subcutaneous site can reverse hyperglycemia in diabetic recipients. Regarding shapes of a bioartificial pancreas, it is believed that a bag form has an advantage because it is easy to prepare a large quantity. Our group previously reported successful transplantation of a bioartificial pancreas in bag form, a mesh-reinforced polyvinyl alcohol bag (MRPB), implanted in the peritoneal cavity. We also reported that the effect of subcutaneous islet transplantation can be greatly improved with prevascularization treatment. In the present study, we attempted to combine MRPB to our protocol of subcutaneous prevascularization. The main problem of this trial is that the procedure of MRPB implantation injures the prevascularized blood vessel networks. To solve this problem, we made a slight alternation in our protocol, and designed new devices on the basis of MRPB. The new devices, possessing the ability to induce neovascularization, were prepared by collagen coating on the surface of MRPB and were implanted with/without different doses of FGF-2 impregnated in gelatin microspheres. When using 5 microg of FGF-2, more blood vessels were observed on the surface of type I/IV collagen-coated MRPB compared with the original MRPB and type I collagen-coated MRPB. Quite a few blood vessels were observed either around the injection site of 50 microg of FGF-2 impregnated in gelatin microspheres alone or around the implantation site of FGF-2-free gelatin microspheres and type I collagen-coated MRPB or type I/IV collagen-coated MRPB. Here we demonstrated that the combination of both FGF-2 impregnated in gelatin microspheres and collagen-coated MRPB could give an effective system of neovascularization suitable for subcutaneous implantation of a bioartificial pancreas.

Animals↗
PubMed2003

Biodegradable microspheres targeting mucosal immune-regulating cells: new approach for treatment of inflammatory bowel disease.

Several studies have indicated that active monocytes, such as macrophages and T cells, play an important role in the pathogenesis of chronic human inflammatory bowel disease (IBD), although the etiology remains unclear. Manipulation of these cells appears essential for the treatment of patients with IBD. Recently, considerable attention has been paid to the use of polymer microspheres for the sustained release of various drugs and the targeting of therapeutic agents to their site of action. It was reported that biodegradable poly-D,L-lactic acid (PDLLA) microspheres can be efficiently taken up by macrophages and M cells. We evaluated the effect of a new drug delivery system targeting microfold cells and macrophages with PDLLA microspheres and gelatin microspheres (GM) on colitis models. In the first experiment, colitis was induced in Balb/c mice by 5% dextran sodium sulfate, and microspheres containing dexamethsone (Decadrone, Dx; Dx microspheres) were orally administered to these mice. Serum levels of Dx did not reach a detectable level after administration of Dx microspheres. The tissue distribution of microspheres containing 125I-Dx in inflamed colon was significantly higher than that in other organs. The histological score, myeloperoxidase activity, and nitric oxide production of mice treated with Dx microspheres were significantly lower than in those treated with Dx alone. Gene expression of proinflammatory cytokines was remarkably downregulated in mice treated with Dx microspheres compared to Dx alone. Next, we investigated the effect of elimination of resident macrophages using microspheres containing dichloromethylene diphosphonate (DMDP) on IL-10 knockout mice. We administered DMDP microspheres to IL-10 KO mice rectally and assessed whether this reagent could reduce the number of local Mac-1-positive cells in the intestine and suppress the development of colitis in IL-10 KO mice. DMDP microspheres reduced the numbers of resident macrophages in the colon of IL-10 KO mice but did not reduce the percentage of Mac-1-positive cells in the spleen, peritoneal cavity, or mesenteric lymph nodes. Depletion of intestinal macrophages significantly suppressed development of chronic colitis in IL-10 KO mice, however. Third, we developed gelatin microspheres containing IL-10, which can be released sustainedly to a local site without losing bioactivity. We administered these microspheres to IL-10 KO mice rectally to investigate whether this treatment can ameliorate colitis. Colonic inflammation in mice treated with GM-IL-10 is remarkably reduced compared to those treated with IL-10 alone. Moreover, expression of CD 40 on Mac-1-positive cells treated with GM-IL-10 is decreased more notably than in mice treated with IL-10 alone. These data suggest that a drug delivery system using these microspheres containing immunomodulatory agents may be a therapeutic approach to human IBD.

Absorbable Implants↗
PubMed2003

[Significance of tissue engineering in clinical practice of regenerative medicine].

It is undoubtedly important for regenerative medicine to discover and use the cells of high proliferation and differentiation potentials. However, there are numerous cases where the tissue regeneration cannot be always achieved only by using the cells. Thus, an environmental site suitable for enabling cells to induce tissue regeneration is highly required for successful tissue regeneration. Tissue engineering is the biomedical technology or methodology indispensable to create this regeneration site while it makes use of the scaffold for cell proliferation and differentiation, the drug delivery system of biological signals, and their combination with cells. This paper describes the present status and research data of tissue engineering to emphasize the considerable significance in regenerative medicine.

Animals↗
PubMed2003

[Development of new therapeutic method for empyema].

OBJECTIVES: We have investigated whether polylactic acid (PLA) sponge and fibroblast-growth-factor (FGF) released slowly from gelatin beads can induce fibrotic tissue in postpneumonectomy dead space. METHODS: Left pneumonectomy was performed in white Japanese rabbits. In the control group (N = 5), left chest was closed without any treatment. In the PLA sponge group (N = 5), PLA sponge and FGF (100 micrograms) released from gelatin beads were introduced into the left chest cavity. RESULTS: In the control group, herniation of the heart and right lung were observed without fibrotic material in the left chest cavity. In the PLA sponge group, dense fibrotic material was observed by chest CT scan 1 month after the operation. Pathological examinations revealed that PLA sponge and FGF did promote the organization of the fibrotic materials. CONCLUSIONS: Fibrotic materials can be induced in the postpneumonectomy dead space by PLA sponge and FGF released slowly from a gelatin sponge. New therapeutic method may be introduced near future by this concept, reduction of dead space with newly developed own fibrotic materials.

Animals↗
PubMed2002

Delivery of interleukin-12 in gelatin hydrogels effectively suppresses development of transplanted colonal carcinoma in mice.

PURPOSE: The sustained effects of interleukin-12 (IL-12) incorporated in biodegradable hydrogel on the development of transplanted colon carcinoma were investigated in C57BC/6 N mice. METHODS: IL-12 was given to the animals incorporated in gelatin hydrogels (GH) which allow its gradual release. As the control administration, IL-12 was given via two subcutaneous injections at an interval of 6 days. Growth of the tumors was evaluated in terms of volume. RESULTS: When IL-12 at 500 ng/animal was administered in GH, the tumor volume was decreased 9 and 12 days after administration, and the response was dose dependent in the range 0-500 ng/animal. The effect of IL-12 was stronger in mice treated with GH than in mice treated by subcutaneous injection at the same dose (i.e. 250 ng/animal twice at an interval of 6 days). Feeding behavior and the post-mortem wet weight of several visceral organs were unchanged after IL-12 administration. Serum parameters relative to the liver, heart and kidneys were unaffected by IL-12 treatment. No noticeable toxicity was detected when the dose of IL-12 in GH was increased to 1000 ng/animal. CONCLUSIONS: The results suggest that IL-12 is effective in suppressing the growth of colon carcinoma, and that delivery of this agent in GH is efficient in the treatment of carcinoma.

Animals↗
PubMed2002

Liver targeting of plasmid DNA by pullulan conjugation based on metal coordination.

Liver targeting of plasmid DNA was achieved through conjugation of pullulan derivatives with chelate residues based on metal coordination. Triethylenetetramine (Ti), diethylenetriamine pentaacetic acid (DTPA), and spermine (Sm) were chemically introduced to pullulan, a polysaccharide with an inherent affinity for the liver, to obtain various pullulan-Ti, pullulan-DTPA, and pullulan-Sm derivatives. Irrespective of the type of pullulan derivatives, intravenous injection of the pullulan derivatives-plasmid DNA conjugates with Zn2+ coordination significantly enhanced the level of gene expression only in the liver to a significant greater extent than that of free plasmid DNA. The enhanced gene expression by the pullulan-DTPA-plasmid DNA conjugate was specific to the liver and the level was significantly higher than that of the pullulan-DTPA-plasmid DNA mixture. The level of gene expression depended on the percentage of chelate residue introduced, the mixing ratio of the plasmid DNA-DTPA residue in conjugate preparation, and the plasmid DNA dose. The gene expression induced by the conjugate lasted over 12 days after injection. A fluorescent-microscopic study revealed that the plasmid DNA was localized at the liver after injection of the pullulan-DTPA-plasmid DNA conjugate with Zn2+ coordination. Pre-injection of both arabinogalactan and galactosylated albumin suppressed significantly the liver level of gene expression, in contrast to that of mannosylated albumin, indicating that the plasmid DNA in the conjugate was transfected at hepatocytes. We conclude that the Zn2+-coordinated pullulan conjugation is a promising way to enable the plasmid DNA to target to the liver for gene expression as well as to prolong the time duration of gene expression

Animals↗
PubMed2002

Liver targeting of human interferon-beta with pullulan based on metal coordination.

Although interferon (IFN)-beta is widely used for the elimination of hepatitis C virus in patients with chronic liver disease, its clinical efficacy is unsatisfactory. Targeting IFN-beta to the liver might enhance its efficacy without increasing its side effects. The objective of the present study was to target IFN-beta to the liver to enhance its biological activity and reduce its side effects. A chelating residue, diethylenetriaminepentaacetic acid (DTPA), was introduced to pullulan, a water-soluble polysaccharide with a high affinity to the liver (DTPA-pullulan) and natural human IFN-beta was coordinately conjugated with the DTPA-pullulan by mixing in an aqueous solution containing zinc ions (Zn(2+)). Intravenous injection of the IFN-beta-DTPA-pullulan conjugate with Zn(2+) coordination into mice enhanced induction of an antiviral enzyme, 2',5'-oligoadenylate synthetase (2-5AS), specifically in the liver to a significantly greater extent than free natural IFN-beta. The enhanced 2-5AS level in the liver depended on the molar mixing ratio of IFN-beta, DTPA residue of the DTPA-pullulan, and Zn(2+). Moreover, the duration of the liver 2-5AS induction by the IFN-beta-DTPA-pullulan conjugate was longer than that by free natural IFN-beta. Thus, human IFN-beta-DTPA-pullulan conjugate appears to be applicable for clinical use, which is promising for treatment of patients with chronic hepatitis C.

Animals↗
PubMed2002

Sustained release of cis-hydroxyproline in the treatment of experimental proliferative vitreoretinopathy in rabbits.

PURPOSE: To evaluate the efficacy of sustained-release cis-4-hydroxyproline (CHP), a proline analog that inhibits collagen secretion, on experimental proliferative vitreoretinopathy (PVR) in rabbits. METHODS: To demonstrate the sustained release of CHP we developed scleral implants weighing 8.5 mg made of a homogeneous mixture of poly( D, L-lactide-co-glycolide) (PLGA) and various doses of CHP. The CHP release profiles were evaluated by high-performance liquid chromatography in vitro. Scleral implants loaded with 20% and 15% of CHP and made from PLGA (copolymer ratios 65/35 and 50/50; mean molecular weights 103,000 and 93,000, respectively) were used to treat experimental PVR and the efficacy was studied. In treated eyes, two PLGA 65/35 implants ( n=7), PLGA 50/50 implants ( n=6), or a PLGA 65/35 and a PLGA 50/50 implant ( n=9) were inserted at the pars plana, followed by PVR induction with autologous fibroblasts. Control eyes ( n=18) received two implants without CHP. Ocular tissue toxicity was evaluated histologically. RESULTS: In vitro release studies demonstrated a triphasic release pattern. The PLGA 65/35 and PLGA 50/50 implants released CHP over 4 and 7 weeks, respectively. The PLGA 65/35 implants decreased the incidence of retinal detachment from 89% (in controls) to 57% on day 28. When both PLGA 65/35 and PLGA 50/50 implants were used, the inhibitory effect was synergistically enhanced ( p=0.0034), while implantation with only PLGA 50/50 implants had no significant effect on PVR. No toxic reactions were observed. CONCLUSION: These results suggest that the biodegradable polymeric implants containing CHP represent a potential treatment for PVR.

Absorbable Implants↗
PubMed2002

Controlled release of plasmid DNA from cationized gelatin hydrogels based on hydrogel degradation.

This paper shows achievement of the in vivo controlled release of a plasmid DNA from a biodegradable hydrogel and the consequent regulation of gene expression period. Cationization of gelatin was preformed through introduction of ethylenediamine and the gelatin prepared was crosslinked by various concentrations of glutaraldehyde to obtain cationized gelatin (CG) hydrogels as the carrier of plasmid DNA. In vivo release of plasmid DNA from the CG hydrogels was compared with the in vivo degradation of hydrogels. When CG hydrogels incorporating 125I-labeled plasmid DNA were implanted into the femoral muscle of mice, the plasmid DNA radioactivity remaining decreased with time and the retention period prolonged with a decrease in the water content of hydrogels used. The higher the water content of 125I-labeled CG hydrogels, the faster the hydrogel radioactivity remaining decreased with time. The time profile of plasmid DNA remaining in the hydrogels was in good accordance with that of hydrogel radioactivity, irrespective of the water content. Intramuscular implantation of plasmid DNA-incorporated CG hydrogels enhanced significantly expression of the plasmid DNA around the implanted site. The retention period of gene expression became longer as the hydrogel water content decreased. Fluorescent microscopic study revealed that the plasmid DNA-CG complex was detected around the hydrogel implanted even after 7-day implantation in marked contrast to the injection of plasmid DNA solution. It was concluded that in our hydrogel system, active plasmid DNA was released accompanied with the in vivo degradation of hydrogel, resulting in extended gene expression. The time profile of plasmid DNA release and the consequent gene expression was controllable by changing the water content of hydrogels.

Animals↗