The Experts below are selected from a list of 3543 Experts worldwide ranked by ideXlab platform
Yasuhiko Shimizu - One of the best experts on this subject based on the ideXlab platform.
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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
Tissue Engineering, 2003Co-Authors: Taka Nakahara, Tatsuo Nakamura, Yasuhiko Tabata, Eizaburo Kobayashi, Masatoshi Inoue, Keiji Shigeno, Yasuhiko ShimizuAbstract: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 syste...
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evaluation of peripheral nerve regeneration across an 80 mm gap using a polyglycolic acid pga Collagen nerve conduit filled with laminin soaked Collagen Sponge in dogs
International Journal of Artificial Organs, 2002Co-Authors: Toshinari Toba, Yoshio Hori, Tatsuo Nakamura, A K Lynn, Kazuya Matsumoto, Seijun Fukuda, Makoto Yoshitani, Yasuhiko ShimizuAbstract:Abstract We evaluated peripheral nerve regeneration using a novel artificial nerve conduit. The conduit was made of a polyglycolic acid(PGA) - Collagen tube filled with laminin- soaked Collagen Sponge. We implanted this nerve conduit across an 80mm gap in the peroneal nerve of dogs. Histological observation 12 months after implantation showed numerous unmyelinated and myelinated nerve fibershad regenerated beyond the gap. Neurofilaments were widely observed immunohistochemically in the regenerated nerve segments. These findings indicated that newly regenerated axons had extended across the gap and connected into the distal nerve segments. Compound muscle action potentials(CMAPs) and somatosensory evoked potentials (SEPs) were recorded in all dogs. At 12 months, the CMAPs indicated complete recovery, while the SEPs showed incomplete but substantial recovery. Walking patterns had returned to near-normal 12 months after implantation. Use of this nerve conduit can lead to peripheral nerve elongation and favorable functional recovery across a wider nerve gap.
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experimental study on in situ tissue engineering of the stomach by an acellular Collagen Sponge scaffold graft
Asaio Journal, 2001Co-Authors: Yoshio Hori, Yoshimochi Kurokawa, Tatsuo Nakamura, Susumu Satomi, Yasuhiko ShimizuAbstract:: We carried out an experimental study to clarify the feasibility of stomach tissue engineering for reconstruction after partial gastrectomy. A Collagen Sponge scaffold was implanted to support the regeneration of stomach tissue. A 4 cm square area of the anterior wall of the stomach was surgically resected in three beagle dogs, and then reconstructed using the Collagen Sponge scaffold. The dogs received intravenous hyperalimentation for 14 days after the operation, and a silicone sheet was used as a patch on the luminal side to protect the scaffold from degradation by digestive juice. The silicone sheet was removed endoscopically 4 weeks after the operation, and the surgical defect was observed endoscopically at various time points. At 4 weeks after surgery, the stomach wall had regenerated, but was not yet covered by stomach mucosal tissue. However, at 16 weeks after surgery, mucosa totally covered the regenerated area. Microscopic findings confirmed regeneration of the stomach wall, mucosa, and thin muscular layer. These results show that tissue engineering of the stomach will be feasible in the near future for reconstruction after partial gastrectomy.
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regeneration of canine peroneal nerve with the use of a polyglycolic acid Collagen tube filled with laminin soaked Collagen Sponge a comparative study of Collagen Sponge and Collagen fibers as filling materials for nerve conduits
Journal of Biomedical Materials Research, 2001Co-Authors: Toshinari Toba, Yoshio Hori, Tatsuo Nakamura, Yasuhiko Shimizu, Kazuya Matsumoto, Seijun Fukuda, Makoto Yoshitani, Katsunori Ohnishi, Hiroki Ueda, Katsuaki EndoAbstract:A novel artificial nerve conduit was developed and its efficiency was evaluated on the basis of promotion of peripheral nerve regeneration across an 80-mm gap in dogs. The nerve conduit was made of a polyglycolic acid–Collagen tube filled with laminin-soaked Collagen Sponge. Conduits filled with either Sponge- or fiber-form Collagen were implanted into an 80-mm gap of the peroneal nerve (five dogs for each form). Twelve months postoperatively nerve regeneration was superior in the Sponge group both morphometrically (percentage of neural tissue: fiber: 39.7 ± 5.2, Sponge: 43.0 ± 4.5, n=3) and electrophysiologically (fiber: CMAP 1.06 ± 0.077, SEP 1.32 ± 0.127 Sponge: CMAP 1.04 ± 0.106, SEP 1.24 ± 0.197, n=5), although these differences were not statistically significant. The observed regeneration was complementary to successful results reported previously in the same model, in which Collagen fibers exclusively were used. The results indicate a possible superiority of Collagen Sponge over Collagen fibers as filling materials. In addition, the mass-producibility, superior scaffolding potential, and capacity for gradual release of soluble factors of the Sponge provide make it an attractive alternative to fine fibers, which are both technologically difficult and costly to produce. This newly developed nerve conduit has the potential to enhance peripheral nerve regeneration across longer gaps commonly encountered in clinical settings. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 58: 622–630, 2001
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tissue engineering of the small intestine by acellular Collagen Sponge scaffold grafting
International Journal of Artificial Organs, 2001Co-Authors: Yoshio Hori, Yoshimochi Kurokawa, Tatsuo Nakamura, Susumu Satomi, Kazuya Matsumoto, Yasuhiko ShimizuAbstract:: Tissue engineering of the small intestine will prove a great benefit to patients suffering from short bowel disease. However cell seeding in tissue engineering, such as fetal cell use, is accompanied by problems of ethical issues, rejection, and short supply. To overcome these problems, we carried out an experimental study on tissue engineering of the small intestine by acellular Collagen Sponge scaffold grafting. We resected the 5 cm long jejunum from beagle dogs and reconstructed it by acellular Collagen Sponge grafting with a silicon tube stent. The graft was covered with the omentum. At 1 month after operation, the silicon stent was removed endoscopically. Animals were sacrificed 1 and 4 months after operation, and were examined microscopically. Neo-intestinal regeneration was observed and the intestinal mucosa covered the luminal side of the regenerated intestine across the anastomosis. Thus, the small intestine was regenerated by tissue engineering technology using an acellular Collagen Sponge scaffold.
Tatsuo Nakamura - One of the best experts on this subject based on the ideXlab platform.
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regeneration of skeletal muscle using in situ tissue engineering on an acellular Collagen Sponge scaffold in a rabbit model
Asaio Journal, 2007Co-Authors: Shuichi Kin, Tatsuo Nakamura, Yuen Nakase, Akeo Hagiwara, Susumu Nakashima, T Yoshikawa, Yoshiaki Kuriu, Chohei Sakakura, Eigo Otsuji, Hisakazu YamagishiAbstract:Because of the limited ability of skeletal muscle to regenerate, resection of a large amount of muscle mass often results in incomplete recovery due to nonfunctional scar tissue. The aim of this study was to regenerate skeletal muscle using in situ tissue engineering in a rabbit model. In 18 male rabbits, a muscle defect (1.0 x ~1.0 x ~0.5 cm) was created in the vastus lateralis of both legs. A piece of cross-linked ateloCollagen Sponge was then inserted into the defect in one leg, whereas the defect in the other leg was left untreated. Both defects were finally covered with fascia. Twenty-four weeks after surgery, the defect that had been filled with the cross-linked ateloCollagen Sponge scaffold showed mild concavity and slight adhesion to the fascia, while the control side showed severe scar formation and shrinkage. Histologically, the regenerating myofibers at the site containing the Collagen Sponge were greater in number, diameter, and length than those at the control site. These results indicate that cross-linked ateloCollagen Sponge has the potential to act as a scaffold for muscle tissue regeneration.
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tissue engineering of small intestinal tissue using Collagen Sponge scaffolds seeded with smooth muscle cells
Tissue Engineering, 2006Co-Authors: Yuen Nakase, Tatsuo Nakamura, Akeo Hagiwara, Syuichi Kin, Susumu Nakashima, T Yoshikawa, Kenichirou Fukuda, Yoshiaki Kuriu, Kouji Miyagawa, Chohei SakakuraAbstract:In a previously reported attempt to regenerate small intestine with autologous tissues, Collagen scaffolds were used without cell seeding or with autologous mesenchymal stem cell seeding. However the regenerated intestine lacked a smooth muscle layer. To accomplish regeneration of a smooth muscle layer, this present study used Collagen scaffolds seeded with the smooth muscle cells (SMC) in a canine model. Autologous SMC were isolated from stomach wall and cultured. Two types of scaffolds were fabricated: in SMC (+), cultured SMCs were mixed with Collagen solution and poured into a Collagen Sponge; and in SMC (−), SMCs were omitted. Both scaffolds were implanted into defects of isolated ileum as a patch graft. Animals were euthanized at 4, 8, and 12 weeks; for the last time point, the ileal loop had been reanastomosed at 8 weeks. At 12 weeks, the SMC (−) group showed a luminal surface covered by a regenerated epithelial cell layer with very short villi; however only a thin smooth muscle layer was observed,...
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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
Tissue Engineering, 2003Co-Authors: Taka Nakahara, Tatsuo Nakamura, Yasuhiko Tabata, Eizaburo Kobayashi, Masatoshi Inoue, Keiji Shigeno, Yasuhiko ShimizuAbstract: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 syste...
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evaluation of peripheral nerve regeneration across an 80 mm gap using a polyglycolic acid pga Collagen nerve conduit filled with laminin soaked Collagen Sponge in dogs
International Journal of Artificial Organs, 2002Co-Authors: Toshinari Toba, Yoshio Hori, Tatsuo Nakamura, A K Lynn, Kazuya Matsumoto, Seijun Fukuda, Makoto Yoshitani, Yasuhiko ShimizuAbstract:Abstract We evaluated peripheral nerve regeneration using a novel artificial nerve conduit. The conduit was made of a polyglycolic acid(PGA) - Collagen tube filled with laminin- soaked Collagen Sponge. We implanted this nerve conduit across an 80mm gap in the peroneal nerve of dogs. Histological observation 12 months after implantation showed numerous unmyelinated and myelinated nerve fibershad regenerated beyond the gap. Neurofilaments were widely observed immunohistochemically in the regenerated nerve segments. These findings indicated that newly regenerated axons had extended across the gap and connected into the distal nerve segments. Compound muscle action potentials(CMAPs) and somatosensory evoked potentials (SEPs) were recorded in all dogs. At 12 months, the CMAPs indicated complete recovery, while the SEPs showed incomplete but substantial recovery. Walking patterns had returned to near-normal 12 months after implantation. Use of this nerve conduit can lead to peripheral nerve elongation and favorable functional recovery across a wider nerve gap.
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experimental study on in situ tissue engineering of the stomach by an acellular Collagen Sponge scaffold graft
Asaio Journal, 2001Co-Authors: Yoshio Hori, Yoshimochi Kurokawa, Tatsuo Nakamura, Susumu Satomi, Yasuhiko ShimizuAbstract:: We carried out an experimental study to clarify the feasibility of stomach tissue engineering for reconstruction after partial gastrectomy. A Collagen Sponge scaffold was implanted to support the regeneration of stomach tissue. A 4 cm square area of the anterior wall of the stomach was surgically resected in three beagle dogs, and then reconstructed using the Collagen Sponge scaffold. The dogs received intravenous hyperalimentation for 14 days after the operation, and a silicone sheet was used as a patch on the luminal side to protect the scaffold from degradation by digestive juice. The silicone sheet was removed endoscopically 4 weeks after the operation, and the surgical defect was observed endoscopically at various time points. At 4 weeks after surgery, the stomach wall had regenerated, but was not yet covered by stomach mucosal tissue. However, at 16 weeks after surgery, mucosa totally covered the regenerated area. Microscopic findings confirmed regeneration of the stomach wall, mucosa, and thin muscular layer. These results show that tissue engineering of the stomach will be feasible in the near future for reconstruction after partial gastrectomy.
David L Butler - One of the best experts on this subject based on the ideXlab platform.
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SBC2007-175814 EFFECT OF MECHANICAL STIMULATION ON THE BIOMECHANICS OF STEM CELL - Collagen Sponge CONSTRUCTS FOR PATELLAR TENDON REPAIR
2020Co-Authors: Natalia Juncosa-melvin, Jason T Shearn, Gregory P Boivin, Marc T Galloway, Cynthia Gooch, David L ButlerAbstract:INTRODUCTION Tendons (rotator cuff, Achilles and patellar tendons) are among the most commonly injured soft tissues This study was undertaken to determine how mechanical stimulation in culture of MSC-type I Collagen Sponge constructs affects the biomechanics and histology of rabbit patellar tendon (PT) defect repairs 12 weeks after surgery. The hypotheses to be tested were that mechanical stimulation would improve: 1) the linear stiffness and linear modulus of the in vitro construct after 2 weeks in culture, and 2) repair biomechanics and histological appearance 12 weeks after implantation. 3) We also hypothesized that the construct and repair stiffness and modulus would be positively correlated, suggesting that the in vitro measure might be a predictor of in vivo repair outcome
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mechanical stimulation increases Collagen type i and Collagen type iii gene expression of stem cell Collagen Sponge constructs for patellar tendon repair
Tissue Engineering, 2007Co-Authors: Natalia Juncosamelvin, Karl S Matlin, Robert W Holdcraft, Victor S Nirmalanandhan, David L ButlerAbstract:Our group has shown that mechanical stimulation increases the stiffness of stem cell-Collagen Sponge constructs at 14 days in culture and subsequent rabbit patellar tendon repairs at 12 weeks postsurgery. What remains unclear is which genes might be responsible for this increase in stiffness. Therefore, the objective of this study was to determine how a tensile stimulus affects the gene expression of stem cell-Collagen Sponge constructs used to repair rabbit central patellar tendon defects. Tissue-engineered constructs were created by seeding mesenchymal stem cells (MSCs) from 10 adult rabbits at 0.14 x 10(6) cells/construct in type I Collagen Sponges. Half of the constructs were mechanically stimulated once every 5 min for 8 h/d to a peak strain of 2.4% for 2 weeks. The other half remained in an incubator without mechanical stimulation for 2 weeks. After 14 days in culture, half of the stimulated and nonstimulated constructs were prepared to determine the expression of Collagen type I, Collagen type III, decorin, fibronectin, and glyceraldehyde-3-phosphate dehydrogenase genes using real-time quantitative reverse transcriptase polymerase chain reaction. The remaining constructs were mechanically tested to determine their mechanical properties. Two weeks of in vitro mechanical stimulation significantly increased Collagen type I and Collagen type III gene expression of the stem cell-Collagen Sponge constructs. Stimulated constructs showed 3 and 4 times greater Collagen type I (p = 0.0001) and Collagen type III gene expression (p = 0.001) than nonstimulated controls. Stimulated constructs also had 2.5 times the linear stiffness and 4 times the linear modulus of nonstimulated constructs. However, mechanical stimulation did not significantly increase decorin or fibronectin gene expression (p = 0.2) after 14 days in culture. This study shows that mechanical stimulation of cell-Sponge constructs produces similar increases in the expression of 2 structural genes, as well as linear stiffness and linear modulus.
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effects of mechanical stimulation on the biomechanics and histology of stem cell Collagen Sponge constructs for rabbit patellar tendon repair
Tissue Engineering, 2006Co-Authors: Natalia Juncosamelvin, Victor S Nirmalanandhan, Jason T Shearn, Gregory P Boivin, Marc T Galloway, Cynthia Gooch, John R West, Gino Bradica, David L ButlerAbstract:The objective of this study was to determine how mechanical stimulation affects the biomechanics and histology of stem cell-Collagen Sponge constructs used to repair central rabbit patellar tendon defects. Autogenous tissue-engineered constructs were created for both in vitro and in vivo analyses by seeding mesenchymal stem cells from 10 adult rabbits at 0.14x10(6) cells/construct in type I Collagen Sponges. Half of these constructs were mechanically stimulated once every 5 min for 8 h/day to a peak strain of 4% for 2 weeks. The other half remained in an incubator without mechanical stimulation for 2 weeks. Samples allocated for in vitro testing revealed that mechanically stimulated constructs had 2.5 times the linear stiffness of nonstimulated constructs. The remaining paired constructs for in vivo studies were implanted in bilateral full-thickness, full-length defects in the central third of rabbit patellar tendons. Twelve weeks after surgery, repair tissues were assigned for biomechanical (7 pairs) and histologic (3 pairs) analyses. Maximum force, linear stiffness, maximum stress, and linear modulus for the stimulated (vs. nonstimulated) repairs averaged 70% (vs. 55%), 85% (vs. 55%), 70% (vs. 50%), and 50% (vs. 40%) of corresponding values for the normal central third of the patellar tendons. The average force-elongation curve for the mechanically stimulated repairs also matched the corresponding curve for the normal patellar tendons, up to 150% of the peak in vivo force values recorded in a previous study. Construct and repair linear stiffness and linear modulus were also positively correlated (r = 0.6 and 0.7, respectively). Histologically both repairs showed excellent cellular alignment and mild staining for decorin and Collagen type V, and moderate staining for fibronectin and Collagen type III. This study shows that mechanical stimulation of stem cell-Collagen Sponge constructs can significantly improve tendon repair biomechanics up to and well beyond the functional limits of in vivo loading.
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the effect of autologous mesenchymal stem cells on the biomechanics and histology of gel Collagen Sponge constructs used for rabbit patellar tendon repair
Tissue Engineering, 2006Co-Authors: Natalia Juncosamelvin, Gregory P Boivin, Marc T Galloway, Cynthia Gooch, John R West, Michael G Dunn, David L ButlerAbstract:The objective of this study was to introduce mesenchymal stem cells (MSCs) into a gel-Sponge composite and examine the effect the cells have on repair biomechanics and histology 12 weeks postsurgery. We tested two related hypotheses-adding MSCs would significantly improve repair biomechanics and cellular organization, and would result in higher failure forces than peak in vivo patellar tendon (PT) forces recorded for an inclined hopping activity. Autogenous tissue-engineered constructs were created by seeding MSCs from 15 adult rabbits at 0.1 x 10(6) cells/mL in 2.6 mg/mL of Collagen gel in Collagen Sponges. Acellular constructs were created using the same concentration of Collagen gel in matching Collagen Sponges. These cellular and acellular constructs were implanted in bilateral full-thickness, full-length defects in the central third of patellar tendons. At 12 weeks after surgery, repair tissues were assigned for biomechanical (n = 12 pairs) and histological (n = 3 pairs) analyses. Maximum force and maximum stress for the cellular repairs were about 60 and 50% of corresponding values for the normal central third of the PT, respectively. Likewise, linear stiffness and linear modulus for these cellular repairs averaged 75 and 30% of normal PT values, respectively. By contrast, the acellular repairs exhibited lower percentages of normal PT values for maximum force (40%), maximum stress (25%), linear stiffness (30%), and linear modulus (20%). Histologically, both repairs showed strong staining for Collagen types III and V, fibronectin, and decorin. The cellular repairs also showed cellular alignment comparable to that of normal tendon. This study shows that introducing autogenous mesenchymal stem cells into a gel-Collagen Sponge composite significantly improves tendon repair compared to the use of a gel-Sponge composite alone in the range of in vivo loading.
Yasuhiko Tabata - One of the best experts on this subject based on the ideXlab platform.
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ectopic bone formation in Collagen Sponge self assembled peptide amphiphile nanofibers hybrid scaffold in a perfusion culture bioreactor
Biomaterials, 2006Co-Authors: Hossein Hosseinkhani, Mohsen Hosseinkhani, Furong Tian, Hisatoshi Kobayashi, Yasuhiko TabataAbstract:Abstract The objective of this study was to enhance ectopic bone formation in a three-dimensional (3-D) hybrid scaffold in combination with bioreactor perfusion culture system. The hybrid scaffold consists of two biomaterials, a hydrogel formed through self-assembly of peptide–amphiphile (PA) with cell suspensions in media, and a Collagen Sponge reinforced with poly(glycolic acid) (PGA) fiber incorporation. PA was synthesized by standard solid-phase chemistry that ends with the alkylation of the NH 2 terminus of the peptide. A 3-D network of nanofibers was formed by mixing cell suspensions in media with dilute aqueous solution of PA. Scanning electron microscopy (SEM) observation revealed the formation of fibrous assemblies with an extremely high aspect ratio and high surface areas. Osteogenic differentiation of mesenchymal stem cells (MSC) in the hybrid scaffold was greatly influenced by the perfusion culture method compared with static culture method. When the osteoinduction activity of hybrid scaffold was studied following the implantation into the back subcutis of rats in terms of histological and biochemical examinations, significantly homogeneous bone formation was histologically observed throughout the hybrid scaffolds when perfusion culture was used compared with static culture method. The level of alkaline phosphatase activity and osteocalcin content at the implanted sites of hybrid scaffolds were significantly high for the perfusion group compared with those in static culture method. We conclude that combination of MSC-seeded hybrid scaffold and the perfusion method was promising to enhance in vitro osteogenic differentiation of MSC and in vivo ectopic bone formation.
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perfusion culture enhances osteogenic differentiation of rat mesenchymal stem cells in Collagen Sponge reinforced with poly glycolic acid fiber
Tissue Engineering, 2005Co-Authors: Hossein Hosseinkhani, Yasuyuki Inatsugu, Yosuke Hiraoka, Sachiko Inoue, Yasuhiko TabataAbstract:The objective of this study was to obtain fundamental knowledge about in vitro culture systems to enhance the proliferation and differentiation of mesenchymal stem cells (MSCs) in Collagen Sponge reinforced by the incorporation of poly(glycolic acid) (PGA) fiber. A Collagen solution with PGA fiber homogeneously localized at PGA:Collagen weight ratios of 0.67, 1.25, 2.5, and 5 was freezedried, followed by cross-linking of combined dehydrothermal, glutaraldehyde, and ultraviolet treatment. Scanning electron microscopy revealed that Collagen Sponges exhibited homogeneous and interconnected pore structures with an average size of 180 microm, irrespective of PGA fiber incorporation. When rat MSCs were seeded into Collagen Sponge with or without PGA fiber incorporation, more attached cells were observed in Collagen Sponge incorporating PGA fiber than in Collagen Sponge without PGA fiber incorporation, irrespective of the PGA:Collagen ratio. The proliferation and osteogenic differentiation of MSCs in PGA-reinforced Sponge at a weight ratio of 5 were greatly influenced by the culture method and growth conditions. Alkaline phosphatase (ALP) activity and osteocalcin content of MSCs cultured in PGA-reinforced Sponge by the perfusion method became maximum at a flow rate of 0.2 mL/min, although they increased with culture time period. It may be concluded that appropriate perfusion conditions enable MSCs to positively improve the extent of proliferation and differentiation.
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cavernous nerve reconstruction with a biodegradable conduit graft and Collagen Sponge in the rat
The Journal of Urology, 2005Co-Authors: Shinichi Hisasue, Yasuhiko Tabata, Ryuichi Kato, Yoshikazu Sato, Takahiro Suetomi, Taiji TsukamotoAbstract:ABSTRACTPurpose: We investigated the efficacy of a biodegradable conduit graft for axonal regeneration of the injured cavernous nerve in a rat model.Materials and Methods: Bilateral cavernous nerves were resected in 8-week-old Sprague-Dawley rats. We interposed a nerve gap with a 4 mm poly L-lactic acid and E-caprolactone copolymer conduit. The 56 rats were divided into 4 groups, namely group 1—biodegradable conduit alone, group 2—biodegradable conduit plus Collagen Sponge, group 3—sham operation as a positive control and group 4—unconnected conduit as a negative control.Results: Immunohistochemical study revealed that neuronal nitric oxide synthase positive nerve fibers significantly increased in all rats in the conduit graft groups at 3 months. In a retrograde tracing study with FluoroGold (Fluorochrome, Englewood, Colorado) at 3 months the conduit plus Collagen group showed a significant increase in FluoroGold positive cells in major pelvic ganglia. Intracavernous pressure elicited by medial preoptic a...
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fabrication and biocompatibility of Collagen Sponge reinforced with poly glycolic acid fiber
Tissue Engineering, 2003Co-Authors: Yosuke Hiraoka, Hiroki Ueda, Yu Kimura, Yasuhiko TabataAbstract:This article describes an investigation of Collagen Sponge mechanically reinforced through the incorporation of poly(glycolic acid) (PGA) fiber. A Collagen solution with PGA fiber homogeneously dispersed at Collagen:PGA weight ratios of 1.5, 0.8, 0.4, and 0.2 was freeze-dried, followed by dehydrothermal cross-linking to obtain Collagen Sponges incorporating PGA fiber to various extents. By scanning electron microscopy observation, the Collagen Sponges exhibited isotropic and interconnected pore structures with an average size of 180 μm, irrespective of PGA fiber incorporation. As expected, PGA fiber incorporation enabled the Collagen Sponges to significantly enhance their compression strength. In vitro cell culture studies revealed that the number of L929 fibroblasts initially attached was significantly greater for any Collagen Sponge incorporating PGA fiber than for Collagen Sponge. The shrinkage of Sponge after cell seeding was suppressed by fiber incorporation. It is possible that shrinkage suppression...
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adipose tissue engineering based on human preadipocytes combined with gelatin microspheres containing basic fibroblast growth factor
Biomaterials, 2003Co-Authors: Yu Kimura, Makoto Ozeki, Takashi Inamoto, Yasuhiko TabataAbstract:Gelatin microspheres containing basic fibroblast growth factor (bFGF) were prepared for the controlled release of bFGF. Co-implantation with the gelatin microspheres enabled preadipocytes to induce adipose tissue formation at the implanted site. Preadipocytes isolated from human fat tissue were suspended with the gelatin microspheres containing bFGF and incorporated into a Collagen Sponge of cell scaffold. Following subcutaneous implantation of the Collagen Sponge incorporating human preadipocytes, and gelatin microspheres containing 1 microg of bFGF into the back of nude mice, adipose tissue was formed at the implanted site of Collagen Sponge within 6 weeks postoperatively although the extent depended on the number of preadipocytes transplanted and the bFGF dose. The formation of adipose tissue was significant compared with the implantation of Collagen Sponge incorporating human preadipocytes and 1 microg of free bFGF. The area of adipose tissue newly formed was increased with the number of preadipocytes transplanted until to 1.0 x 10(5) cells/site and thereafter leveled off. The maximum area was observed at the bFGF dose of 1 microg/site. The area was significantly smaller at the bFGF dose of 0.5 microg/site or larger than 1 microg/site. Immunohistochemical examination indicated that the adipose tissue newly formed was composed of human matured adipocytes. No adipogenesis was observed at the implanted site of Collagen Sponge incorporating either gelatin microspheres containing bFGF or human preadipocytes and the mixed gelatin microspheres containing bFGF and human preadipocytes. We conclude that combination of gelatin microspheres containing bFGF and preadipocytes with the Collagen Sponge is essential to achieve tissue engineering of fat tissue.
Natalia Juncosamelvin - One of the best experts on this subject based on the ideXlab platform.
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mechanical stimulation increases Collagen type i and Collagen type iii gene expression of stem cell Collagen Sponge constructs for patellar tendon repair
Tissue Engineering, 2007Co-Authors: Natalia Juncosamelvin, Karl S Matlin, Robert W Holdcraft, Victor S Nirmalanandhan, David L ButlerAbstract:Our group has shown that mechanical stimulation increases the stiffness of stem cell-Collagen Sponge constructs at 14 days in culture and subsequent rabbit patellar tendon repairs at 12 weeks postsurgery. What remains unclear is which genes might be responsible for this increase in stiffness. Therefore, the objective of this study was to determine how a tensile stimulus affects the gene expression of stem cell-Collagen Sponge constructs used to repair rabbit central patellar tendon defects. Tissue-engineered constructs were created by seeding mesenchymal stem cells (MSCs) from 10 adult rabbits at 0.14 x 10(6) cells/construct in type I Collagen Sponges. Half of the constructs were mechanically stimulated once every 5 min for 8 h/d to a peak strain of 2.4% for 2 weeks. The other half remained in an incubator without mechanical stimulation for 2 weeks. After 14 days in culture, half of the stimulated and nonstimulated constructs were prepared to determine the expression of Collagen type I, Collagen type III, decorin, fibronectin, and glyceraldehyde-3-phosphate dehydrogenase genes using real-time quantitative reverse transcriptase polymerase chain reaction. The remaining constructs were mechanically tested to determine their mechanical properties. Two weeks of in vitro mechanical stimulation significantly increased Collagen type I and Collagen type III gene expression of the stem cell-Collagen Sponge constructs. Stimulated constructs showed 3 and 4 times greater Collagen type I (p = 0.0001) and Collagen type III gene expression (p = 0.001) than nonstimulated controls. Stimulated constructs also had 2.5 times the linear stiffness and 4 times the linear modulus of nonstimulated constructs. However, mechanical stimulation did not significantly increase decorin or fibronectin gene expression (p = 0.2) after 14 days in culture. This study shows that mechanical stimulation of cell-Sponge constructs produces similar increases in the expression of 2 structural genes, as well as linear stiffness and linear modulus.
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effects of mechanical stimulation on the biomechanics and histology of stem cell Collagen Sponge constructs for rabbit patellar tendon repair
Tissue Engineering, 2006Co-Authors: Natalia Juncosamelvin, Victor S Nirmalanandhan, Jason T Shearn, Gregory P Boivin, Marc T Galloway, Cynthia Gooch, John R West, Gino Bradica, David L ButlerAbstract:The objective of this study was to determine how mechanical stimulation affects the biomechanics and histology of stem cell-Collagen Sponge constructs used to repair central rabbit patellar tendon defects. Autogenous tissue-engineered constructs were created for both in vitro and in vivo analyses by seeding mesenchymal stem cells from 10 adult rabbits at 0.14x10(6) cells/construct in type I Collagen Sponges. Half of these constructs were mechanically stimulated once every 5 min for 8 h/day to a peak strain of 4% for 2 weeks. The other half remained in an incubator without mechanical stimulation for 2 weeks. Samples allocated for in vitro testing revealed that mechanically stimulated constructs had 2.5 times the linear stiffness of nonstimulated constructs. The remaining paired constructs for in vivo studies were implanted in bilateral full-thickness, full-length defects in the central third of rabbit patellar tendons. Twelve weeks after surgery, repair tissues were assigned for biomechanical (7 pairs) and histologic (3 pairs) analyses. Maximum force, linear stiffness, maximum stress, and linear modulus for the stimulated (vs. nonstimulated) repairs averaged 70% (vs. 55%), 85% (vs. 55%), 70% (vs. 50%), and 50% (vs. 40%) of corresponding values for the normal central third of the patellar tendons. The average force-elongation curve for the mechanically stimulated repairs also matched the corresponding curve for the normal patellar tendons, up to 150% of the peak in vivo force values recorded in a previous study. Construct and repair linear stiffness and linear modulus were also positively correlated (r = 0.6 and 0.7, respectively). Histologically both repairs showed excellent cellular alignment and mild staining for decorin and Collagen type V, and moderate staining for fibronectin and Collagen type III. This study shows that mechanical stimulation of stem cell-Collagen Sponge constructs can significantly improve tendon repair biomechanics up to and well beyond the functional limits of in vivo loading.
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the effect of autologous mesenchymal stem cells on the biomechanics and histology of gel Collagen Sponge constructs used for rabbit patellar tendon repair
Tissue Engineering, 2006Co-Authors: Natalia Juncosamelvin, Gregory P Boivin, Marc T Galloway, Cynthia Gooch, John R West, Michael G Dunn, David L ButlerAbstract:The objective of this study was to introduce mesenchymal stem cells (MSCs) into a gel-Sponge composite and examine the effect the cells have on repair biomechanics and histology 12 weeks postsurgery. We tested two related hypotheses-adding MSCs would significantly improve repair biomechanics and cellular organization, and would result in higher failure forces than peak in vivo patellar tendon (PT) forces recorded for an inclined hopping activity. Autogenous tissue-engineered constructs were created by seeding MSCs from 15 adult rabbits at 0.1 x 10(6) cells/mL in 2.6 mg/mL of Collagen gel in Collagen Sponges. Acellular constructs were created using the same concentration of Collagen gel in matching Collagen Sponges. These cellular and acellular constructs were implanted in bilateral full-thickness, full-length defects in the central third of patellar tendons. At 12 weeks after surgery, repair tissues were assigned for biomechanical (n = 12 pairs) and histological (n = 3 pairs) analyses. Maximum force and maximum stress for the cellular repairs were about 60 and 50% of corresponding values for the normal central third of the PT, respectively. Likewise, linear stiffness and linear modulus for these cellular repairs averaged 75 and 30% of normal PT values, respectively. By contrast, the acellular repairs exhibited lower percentages of normal PT values for maximum force (40%), maximum stress (25%), linear stiffness (30%), and linear modulus (20%). Histologically, both repairs showed strong staining for Collagen types III and V, fibronectin, and decorin. The cellular repairs also showed cellular alignment comparable to that of normal tendon. This study shows that introducing autogenous mesenchymal stem cells into a gel-Collagen Sponge composite significantly improves tendon repair compared to the use of a gel-Sponge composite alone in the range of in vivo loading.