Publications by authors named "In Kyong Shim"

34 Publications

Acetazolamide-eluting biodegradable tubular stent prevents pancreaticojejunal anastomotic leakage.

J Control Release 2021 Jul 10;335:650-659. Epub 2021 Jun 10.

Biomedical Engineering Research Center, Asan Institute for Life Sciences, Asan Medical Center, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Republic of Korea; Division of Hepatobiliary Pancreas Surgery, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Republic of Korea; Asan Medical Institute of Convergence Science and Technology (AMIST), Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Republic of Korea. Electronic address:

Postoperative pancreatic fistula at the early stage can lead to auto-digestion, which may delay the recovery of the pancreaticojejunal (PJ) anastomosis. The efficacy and safety of an acetazolamide-eluting biodegradable tubular stent (AZ-BTS) for the prevention of self-digestion and intra-abdominal inflammatory diseases caused by pancreatic juice leakage after PJ anastomosis in a porcine model were investigated. The AZ-BTS was successfully fabricated using a multiple dip-coating process. Then, the drug amount and release profile were analyzed. The therapeutic effects of AZ were examined in vitro using two kinds of pancreatic cancer cell lines, AsPC-1 and PANC-1. The efficacy of AZ-BTS was assessed in a porcine PJ leakage model, with animals were each assigned to a leakage group, a BTS group and an AZ-BTS group. The overall mortality rates in these three groups were 44.4%, 16.6%, and 0%, respectively. Mean α-amylase concentrations were significantly higher in the leakage and BTS groups than in the AZ-BTS group on day 2-5 (p < 0.05 each all). The luminal diameters and areas of the pancreatic duct were significantly larger in the leakage group than in the BTS and AZ-BTS groups (p < 0.05 each all). These findings indicate that AZ-BTS can significantly suppress intra-abdominal inflammatory diseases caused by pancreatic juice leakage and also prevent late stricture formation at the PJ anastomotic site in a porcine model.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jconrel.2021.06.010DOI Listing
July 2021

Allogeneic epithelial cell sheet transplantation for preventing esophageal stricture after circumferential ESD in a porcine model: preliminary results.

Scand J Gastroenterol 2021 May 25;56(5):598-603. Epub 2021 Mar 25.

Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Objectives: Circumferential endoscopic submucosal dissection (ESD) for large lesions induces severe stricture, requiring subsequent treatment. We aimed to evaluate the efficacy of allogeneic epithelial cell sheet transplantation in preventing esophageal stricture after circumferential ESD in a porcine model.

Materials And Methods: A total of 15 conventional pigs underwent a 4 cm long circumferential ESD in the mid-esophagus. Out of these animals, 11 were immediately subjected to allogeneic oral mucosal cell sheet transplantation at the resection site, whereas four pigs underwent circumferential ESD only. We performed upper endoscopy 1 and 2 weeks after ESD and assessed the degree of esophageal stricture and histologic characteristics.

Results: Dysphagia scores and weight change ratios recorded 1 and 2 weeks after ESD did not differ between the two groups. The stricture rate 2 weeks after ESD was 100% in the control group and 90.9% in the cell sheet group ( = 1.000). The median mucosal constriction rates of the control and cell sheet groups were 73.5% (range 63.0-80.0%) and 53.8% (37.5-73.3%,  = .018), respectively. With regard to microscopic measurements, the length of re-epithelialization was greater in the cell sheet group than in the control group (2,495 µm vs. 369 µm,  = .008). Median fibrosis thickness and degree of muscle damage were not significantly different between groups.

Conclusions: Although allogeneic epithelial cell sheet transplantation showed greater re-epithelialization and less mucosal constriction of post-ESD ulcers, it was not sufficiently effective in preventing post-ESD stricture.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/00365521.2021.1897669DOI Listing
May 2021

Improvement of the therapeutic capacity of insulin-producing cells trans-differentiated from human liver cells using engineered cell sheet.

Stem Cell Res Ther 2021 01 6;12(1). Epub 2021 Jan 6.

Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Background: Although pancreatic islet transplantation therapy is ideal for diabetes patients, several hurdles have prevented it from becoming a standard treatment, including donor shortage and low engraftment efficacy. In this study, we prepared insulin-producing cells trans-differentiated from adult human liver cells as a new islet source. Also, cell sheet formation could improve differentiation efficiency and graft survival.

Methods: Liver cells were expanded in vitro and trans-differentiated to IPCs using adenovirus vectors carrying human genes for PDX1, NEUROD1, and MAFA. IPCs were seeded on temperature-responsive culture dishes to form cell sheets. Differentiation efficiency was confirmed by ß cell-specific gene expression, insulin production, and immunohistochemistry. IPC suspension was injected by portal vein (PV), and IPC sheet was transplanted on the liver surface of the diabetic nude mouse. The therapeutic effect of IPC sheet was evaluated by comparing blood glucose control, weight gain, histological evaluation, and hepatotoxicity with IPC injection group. Also, cell biodistribution was assessed by in vivo/ex vivo fluorescence image tagging.

Results: Insulin gene expression and protein production were significantly increased on IPC sheets compared with those in IPCs cultured on conventional culture dishes. Transplanted IPC sheets displayed significantly higher engraftment efficiency and fewer transplanted cells in other organs than injected IPCs, and also lower liver toxicity, improved blood glucose levels, and weight gain. Immunohistochemical analyses of liver tissue revealed positive staining for PDX1 and insulin at 1, 2, and 4 weeks after IPC transplantation.

Conclusions: In conclusion, cell sheet formation enhanced the differentiation function and maturation of IPCs in vitro. Additionally, parameters for clinical application such as distribution, therapeutic efficacy, and toxicity were favorable. The cell sheet technique may be used with IPCs derived from various cell sources in clinical applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13287-020-02080-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7786992PMC
January 2021

Spheroid Fabrication Using Concave Microwells Enhances the Differentiation Efficacy and Function of Insulin-Producing Cells via Cytoskeletal Changes.

Cells 2020 11 27;9(12). Epub 2020 Nov 27.

Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea.

Pancreatic islet transplantation is the fundamental treatment for insulin-dependent diabetes; however, donor shortage is a major hurdle in its use as a standard treatment. Accordingly, differentiated insulin-producing cells (DIPCs) are being developed as a new islet source. Differentiation efficiency could be enhanced if the spheroid structure of the natural islets could be recapitulated. Here, we fabricated DIPC spheroids using concave microwells, which enabled large-scale production of spheroids of the desired size. We prepared DIPCs from human liver cells by trans-differentiation using transcription factor gene transduction. Islet-related gene expression and insulin secretion levels were higher in spheroids compared to those in single-cell DIPCs, whereas actin-myosin interactions significantly decreased. We verified actin-myosin-dependent insulin expression in single-cell DIPCs by using actin-myosin interaction inhibitors. Upon transplanting cells into the kidney capsule of diabetic mouse, blood glucose levels decreased to 200 mg/dL in spheroid-transplanted mice but not in single cell-transplanted mice. Spheroid-transplanted mice showed high engraftment efficiency in in vivo fluorescence imaging. These results demonstrated that spheroids fabricated using concave microwells enhanced the engraftment and functions of DIPCs via actin-myosin-mediated cytoskeletal changes. Our strategy potentially extends the clinical application of DIPCs for improved differentiation, glycemic control, and transplantation efficiency of islets.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/cells9122551DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7768489PMC
November 2020

Engineered Cell Sheets for the Effective Delivery of Adipose-Derived Stem Cells for Tendon-to-Bone Healing.

Am J Sports Med 2020 11 14;48(13):3347-3358. Epub 2020 Oct 14.

Department of Orthopedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Background: Efforts are being made to treat rotator cuff tears (RCTs) that exhibit poor healing and high retear rates. Tendon-to-bone healing using mesenchymal stem cells is being explored, but research is needed to establish effective delivery options.

Purpose: To evaluate the effects of an adipose-derived stem cell (ADSC) sheet on mesenchymal stem cell delivery for tendon-to-bone healing of a chronic RCT in rats and to demonstrate that ADSC sheets enhance tendon-to-bone healing.

Study Design: Controlled laboratory study.

Methods: Mesenchymal stem cells were obtained from rat adipose tissue, and a cell sheet was prepared using a temperature-responsive dish. To evaluate the efficacy of stem cells produced in a sheet for the lesion, the experiment was conducted with 3 groups: repair group, cell sheet transplantation after repair group, and cell sheet-only group. Histological, biomechanical, and micro-computed tomography (micro-CT) results were compared among the groups.

Results: Hematoxylin and eosin staining for histomorphological analysis revealed that the cell sheet transplantation after repair group (5.75 ± 0.95) showed statistically significant higher scores than the repair (2.75 ± 0.50) and cell sheet-only (3.25 ± 0.50) groups ( < .001). On safranin O staining, the cell sheet transplantation after repair group (0.51 ± 0.04 mm) had a larger fibrocartilage area than the repair (0.31 ± 0.06 mm) and cell sheet-only (0.32 ± 0.03 mm) groups ( = .001). On micro-CT, bone volume/total volume values were significantly higher in the cell sheet transplantation after repair group (23.98% ± 1.75%) than in the other groups ( < .039); there was no significant difference in the other values. On the biomechanical test, the cell sheet transplantation after repair group (4 weeks after repair) showed significantly higher results than the other groups ( < .005).

Conclusion: Our study shows that engineered stem cells are a clinically feasible stem cell delivery tool for rotator cuff repair.

Clinical Relevance: This laboratory study provides evidence that ADSCs are effective in repairing RCTs, which are common sports injuries.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1177/0363546520964445DOI Listing
November 2020

Evaluation of Multi-Layered Pancreatic Islets and Adipose-Derived Stem Cell Sheets Transplanted on Various Sites for Diabetes Treatment.

Cells 2020 08 31;9(9). Epub 2020 Aug 31.

Department of Medical Science, Asan Medical Institute of Convergence Science and Technology (AMIST), Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea.

Islet cell transplantation is considered an ideal treatment for insulin-deficient diabetes, but implantation sites are limited and show low graft survival. Cell sheet technology and adipose-derived stem cells (ADSCs) can be useful tools for improving islet cell transplantation outcomes since both can increase implantation efficacy and graft survival. Herein, the optimal transplantation site in diabetic mice was investigated using islets and stem cell sheets. We constructed multi-layered cell sheets using rat/human islets and human ADSCs. Cell sheets were fabricated using temperature-responsive culture dishes. Islet/ADSC sheet (AI sheet) group showed higher viability and glucose-stimulated insulin secretion than islet-only group. Compared to islet transplantation alone, subcutaneous AI sheet transplantation showed better blood glucose control and CD31+ vascular traits. Because of the adhesive properties of cell sheets, AI sheets were easily applied on liver and peritoneal surfaces. Liver or peritoneal surface grafts showed better glucose control, weight gain, and intraperitoneal glucose tolerance test (IPGTT) profiles than subcutaneous site grafts using both rat and human islets. Stem cell sheets increased the therapeutic efficacy of islets in vivo because mesenchymal stem cells enhance islet function and induce neovascularization around transplanted islets. The liver and peritoneal surface can be used more effectively than the subcutaneous site in future clinical applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/cells9091999DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7563383PMC
August 2020

Long-term reversal of diabetes by subcutaneous transplantation of pancreatic islet cells and adipose-derived stem cell sheet using surface-immobilized heparin and engineered collagen scaffold.

BMJ Open Diabetes Res Care 2020 06;8(1)

Department of Medical Science, Asan Medical Institute of Convergence Science and Technology (AMIST), Asan Medical Center, University of Ulsan College of Medicine, Seoul, The Republic of Korea

Objective: Esterified collagen (EC) can be functionalized with heparin to enhance islet graft stability. Growth factors secreted by human adipose-derived stem cells (hADSCs) can bind efficiently to EC-heparin (EC-Hep), which enhances revascularization and cell protection. We investigated the therapeutic potential of a combined heparin-esterified collagen-hADSC (HCA)-islet sheet to enhance islet engraftment.

Research Design And Methods: This study was designed to assess the efficiency of using EC-Hep as a scaffold for subcutaneous islet transplantation in diabetic athymic mice. After the hADSC-cocultured islets were seeded in the EC-Hep scaffold, islet function was measured by glucose-stimulated insulin secretion test and growth factors in the culture supernatants were detected by protein array. Islet transplantation was performed in mice, and graft function and survival were monitored by measuring the blood glucose levels. β-Cell mass and vascular densities were assessed by immunohistochemistry.

Results: The EC-Hep composite allowed sustained release of growth factors. Secretion of growth factors and islet functionality in the HCA-islet sheet were significantly increased compared with the control groups of islets alone or combined with native collagen. In vivo, stable long-term glucose control by the graft was achieved after subcutaneous transplantation of HCA-islet sheet due to enhanced capillary network formation around the sheet.

Conclusions: The findings indicate the potential of the HCA-islet sheet to enhance islet revascularization and engraftment in a hADSC dose-dependent manner, following clinical islet transplantation for the treatment of diabetes mellitus.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/bmjdrc-2019-001128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7307580PMC
June 2020

Coaxial mussel-inspired biofibers: making of a robust and efficacious depot for cancer drug delivery.

J Mater Chem B 2020 06 13;8(23):5064-5079. Epub 2020 May 13.

Intelligent Polymer Research Institute, University of Wollongong, NSW, Australia.

Biopolymer-based hydrogels have emerged as promising platforms for drug delivery systems (DDSs) due to their inherent biocompatibility, tunable physical properties and controllable degradability. Yet, drug release in majority of these systems is solely contingent on diffusion of drug molecules through the hydrogel, which often leads to burst release of drugs from these systems. Herein, inspired by the chemistry of mussel adhesive proteins, a new generation of coaxial hydrogel fibers was developed that could simultaneously exert both affinity and diffusion control over the release of chemotherapeutic drugs. Specifically, dopamine-modified alginate hydrogel along with chemotherapeutic drugs (doxorubicin or gemcitabine) was used as the main core component to confer affinity-controlled release, while a methacrylated-alginate hydrogel was used as the shell composition to provide the controlled diffusion barrier. It was shown that our coaxial mussel-inspired biofibers yielded biocompatible hydrogel fibers (as indicated by comprehensive in vitro and in vivo experiments) with favourable properties including controlled swelling, and enhanced mechanical properties, when compared against single fibers made from unmodified alginate. Notably, it was observed that these coaxial fibers were capable of releasing the two drugs in a slower manner, when compared to single fibers made from pure alginate, which was partly attributed to stronger interactions of drugs with dopamine-modified alginate (the core element of coaxial fibers) as observed from zeta-potential measurements. It was further shown that these drug-loaded coaxial fibers had optimal anticancer activity both in vitro and in vivo using various pancreatic cancer cell lines. Most remarkably, drug loaded coaxial fibers, particularly doxorubicin-containing fibers, had higher anticancer effect in vivo compared to systemic injection of equivalent dosage of the drugs. Altogether, these biocompatible and robust hydrogel fibers may be further used as neoadjuvant or adjuvant therapies for controlled delivery of chemotherapeutic drugs locally to the tumor sites.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d0tb00052cDOI Listing
June 2020

3D cell printing of islet-laden pancreatic tissue-derived extracellular matrix bioink constructs for enhancing pancreatic functions.

J Mater Chem B 2019 03 16;7(10):1773-1781. Epub 2019 Jan 16.

Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Korea.

Type 1 diabetes mellitus (T1DM) is a form of diabetes that inhibits or halts insulin production in the pancreas. Although various therapeutic options are applied in clinical settings, not all patients are treatable with such methods due to the instability of the T1DM or the unawareness of hypoglycemia. Islet transplantation using a tissue engineering-based approach may mark a clinical significance, but finding ways to increase the function of islets in 3D constructs is a major challenge. In this study, we suggest pancreatic tissue-derived extracellular matrix as a potential candidate to recapitulate the native microenvironment in transplantable 3D pancreatic tissues. Notably, insulin secretion and the maturation of insulin-producing cells derived from human pluripotent stem cells were highly up-regulated when cultured in pdECM bioink. In addition, co-culture with human umbilical vein-derived endothelial cells decreased the central necrosis of islets under 3D culture conditions. Through the convergence of 3D cell printing technology, we validated the possibility of fabricating 3D constructs of a therapeutically applicable transplant size that can potentially be an allogeneic source of islets, such as patient-induced pluripotent stem cell-derived insulin-producing cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c8tb02787kDOI Listing
March 2019

A Novel Biodegradable Tubular Stent Prevents Pancreaticojejunal Anastomotic Stricture.

Sci Rep 2020 01 30;10(1):1518. Epub 2020 Jan 30.

Biomedical Engineering Research Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Republic of Korea.

Stricture of pancreatic-enteric anastomoses is a major late complication of a pancreaticoduodenectomy for the treatment of a periampullary tumor and can lead to exocrine and endocrine insufficiency such as malnutrition and diabetes mellitus. We investigated the safety and efficacy of a biodegradable tubular stent (BTS) for preventing a pancreaticojejunostomy (PJ) anastomotic stricture in both a rat and porcine model. The BTS was manufactured using a terpolymer comprising poly p-dioxanone, trimethylene carbonate, and glycolide. A cohort of 42 rats was randomized into 7 groups of 6 animals each after BTS placement into the duodenum for the biodegradation assay. A total of 12 pigs were randomized equally into a control and BTS placement group. The effectiveness of the BTS was assessed by comparing radiologic images with histologic results. Surgical procedures and/or BTS placements were technically successful in all animals. The median mass losses of the removed BTS samples from the rat duodenum were 2.1, 6.8, 11.2, 19.4, 26.1, and 56.8% at 1, 2, 3, 4, 6, and 8 weeks, respectively. The BTS had completely degraded at 12 weeks in the rats. In the porcine PJ model, the mean luminal diameter and area of the pancreatic duct in the control group was significantly larger than in the BTS group (all p < 0.05). BTS placement thus appears to be safe and effective procedure for the prevention of PJ anastomotic stricture. These devices have the potential to be used as a temporary stent placement to treat pancreatic-enteric anastomoses, but further investigations are required for optimization in human.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-019-57271-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992790PMC
January 2020

Pancreatic Tissue-Derived Extracellular Matrix Bioink for Printing 3D Cell-Laden Pancreatic Tissue Constructs.

J Vis Exp 2019 12 13(154). Epub 2019 Dec 13.

Department of Mechanical Engineering, Pohang University of Science and Technology; School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology; Department of Creative IT Engineering, Pohang University of Science and Technology;

The transplantation of pancreatic islets is a promising treatment for patients who suffer from type 1 diabetes accompanied by hypoglycemia and secondary complications. However, islet transplantation still has several limitations such as the low viability of transplanted islets due to poor islet engraftment and hostile environments. In addition, the insulin-producing cells differentiated from human pluripotent stem cells have limited ability to secrete sufficient hormones that can regulate the blood glucose level; therefore, improving the maturation by culturing cells with proper microenvironmental cues is strongly required. In this article, we elucidate protocols for preparing a pancreatic tissue-derived decellularized extracellular matrix (pdECM) bioink to provide a beneficial microenvironment that can increase glucose sensitivity of pancreatic islets, followed by describing the processes for generating 3D pancreatic tissue constructs using a microextrusion-based bioprinting technique.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3791/60434DOI Listing
December 2019

Endoscopic Transplantation of Mesenchymal Stem Cell Sheets in Experimental Colitis in Rats.

Sci Rep 2018 07 27;8(1):11314. Epub 2018 Jul 27.

Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Owing to the recent progress in regenerative medicine technology, clinical trials that harnessed the regeneration and immune modulation potentiality of stem cells for treating IBD have shown promising results. We investigated the feasibility and utility of intraluminal endoscopic transplantation of rat MSC sheets in murine models of experimental colitis for targeted delivery of stem cells to lesions. We isolated adipose-derived mesenchymal stem cells (AD-MSC) and bone marrow-derived mesenchymal stem cells (BM-MSC) from EGFP-transgenic rats and fabricated the cells in sheet forms using temperature-responsive culture dishes. The MSC sheets were endoscopically transplanted to the inflamed area in electrocoagulation and DNBS colitis model. The effect of the transplantation was verified using endoscopic scoring and histological analysis. In the electrocoagulation model, the AD-MSC group showed significantly decreased ulcer size in the transplanted regions. In the DNBS colitis model, the AD-MSC group showed decreased inflammation and colitis in the transplanted regions. Histologic analysis showed that the MSC sheets had successfully attached to the inflamed mucosa in both the electrocoagulation and DNBS colitis model. Our results show that endoscopic transplantation of MSC sheets could be a new effective mode of stem cell therapy for IBD treatment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-018-29617-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6063883PMC
July 2018

Genetic and metabolic comparison of orthotopic and heterotopic patient-derived pancreatic-cancer xenografts to the original patient tumors.

Oncotarget 2018 Jan 21;9(8):7867-7881. Epub 2017 Dec 21.

Division of Hepato-Biliary and Pancreatic Surgery, Department of Surgery, University of Ulsan College of Medicine and Asan Medical Center, Seoul, South Korea.

Tumors from 25 patients with pancreatic cancer were used to establish two patient-derived xenograft (PDX) models: orthotopic PDX (PDOX) and heterotopic (subcutaneous) PDX (PDHX). We compared gene expression by immunohistochemistry, single-nucleotide polymorphism (SNP), DNA methylation, and metabolite levels. The 4 cases, of the total of 13 in which simultaneous PDHX & PDOX models were established, were randomly selected. The molecular-genetic characteristics of the patient's tumor were well maintained in the two PDX models. SNP analysis demonstrated that both groups were more than 90% identical to the original patient's tumor, and there was little difference between the two models. DNA methylation of most genes was similar among the two models and the original patients tumor, but some gene sets were hypermethylated the in PDOX model and hypomethylated in the PDHX model. Most of the metabolites had a similar pattern to those of the original patient tumor in both PDX tumor models, but some metabolites were more prominent in the PDOX and PDHX models. This is the first simultaneous molecular-genetic and metabolite comparison of patient tumors and their tumors established in PDOX and PDHX models. The results indicate high fidelity of these critical properties of the patient tumors in the two models.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.18632/oncotarget.23567DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5814265PMC
January 2018

Engineered mesenchymal stem-cell-sheets patches prevents postoperative pancreatic leakage in a rat model.

Sci Rep 2018 01 10;8(1):360. Epub 2018 Jan 10.

Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Post-operative pancreatic fistula (POPF) following pancreatic resection is a life-threatening surgical complication. Cell sheets were prepared and harvested using temperature-responsive culture dishes and transplanted as patches to seal POPF. Two different mesenchymal stem cell (MSC) sheets were compared in terms of the preventative ability for pancreatic leakage in a rat model. Both rat adipose-derived stem cell (rADSC) and bone marrow-derived stem cell (rBMSC) sheets were transplanted. Those rADSC and rBMSC sheets are created without enzymes and thus maintained their cell-cell junctions and adhesion proteins with intact fibronectin on the basal side, as well as characteristics of MSCs. The rats with post-pancreatectomy rADSC- or rBMSC-sheet patches had significantly decreased abdominal fluid leakage compared with the control group, demonstrated by MR image analysis and measurement of the volume of abdominal fluid. Amylase level was significantly lower in the rats with rADSC-sheet and rBMSC-sheet patches compared with the control groups. The rADSC sheet patches had increased adhesive and immune-cytokine profiles (ICAM-1, L-selectin, TIMP-1), and the rBMSC sheets had reduced immune reactions compared to the control. This is first project looking at the feasibility of tissue engineering therapy using MSC-sheets as tissue patches preventing leakage of abdominal fluid caused by POPF.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-017-18490-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5762914PMC
January 2018

Synergistic effect of a drug loaded electrospun patch and systemic chemotherapy in pancreatic cancer xenograft.

Sci Rep 2017 09 28;7(1):12381. Epub 2017 Sep 28.

Asan Institute for Life Science, University of Ulsan College of Medicine and Asan Medical Center, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul, South Korea.

Pancreatic cancer has a high rate of local recurrence and poor prognosis even with adjuvant chemotherapy after curative resection. The aim of this study was to investigate if local drug delivery combined with low dose systemic chemotherapy can increase the therapeutic effect of chemotherapy while reducing systemic toxicities. Poly-L-lactic acid-based 5-FU releasing patch was fabricated by electrospinning, and its tumour killing effects were first confirmed in vitro. The 5-FU patch directly adhered to the tumour in subcutaneous and orthotopic murine models, and induced a significant decrease in tumour size. Systemic gemcitabine treatment group, 5-FU drug releasing patch group, and systemic gemcitabine plus 5-FU patch group were compared by tumour size measurement, non-invasive bio-imaging, and histology in subcutaneous models. Combination of local drug patch and systemic chemotherapy led to increased tumour suppression effects that lasted longer, as well as increased survival rate. Histology revealed higher degree of apoptosis in the combined group. Systemic toxicity was recovered within 7 days after the treatment in all mice. Conclusively, local drug delivery using biocompatible polymer patch significantly inhibited tumour growth, and combination with systemic chemotherapy was more effective than single systemic chemotherapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-017-12670-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620083PMC
September 2017

Locally-applied 5-fluorouracil-loaded slow-release patch prevents pancreatic cancer growth in an orthotopic mouse model.

Oncotarget 2017 Jun;8(25):40140-40151

Department of Surgery, University of Ulsan College of Medicine & Asan Medical Center, Seoul, South Korea.

To obtain improved efficacy against pancreatic cancer, we investigated the efficacy and safety of a locally-applied 5-fluorouracil (5-FU)-loaded polymeric patch on pancreatic tumors in an orthotopic nude-mouse model. The 5-FU-releasing polymeric patch was produced by 3D printing. After application of the patch, it released the drug slowly for 4 weeks, and suppressed BxPC-3 pancreas cancer growth. Luciferase imaging of BxPC3-Luc cells implanted in the pancreas was performed longitudinally. The drug patch delivered a 30.2 times higher level of 5-FU than an intra-peritoneal (i.p.) bolus injection on day-1. High 5-FU levels were accumulated within one week by the patch. Four groups were compared for efficacy of 5-FU. Drug-free patch as a negative control (Group I); 30% 5-FU-loaded patch (4.8 mg) (Group II); 5-FU i.p. once (4.8 mg) (Group III); 5-FU i.p. once a week (1.2 mg), three times (Group IV). The tumor growth rate was significantly faster in Group I than Group II, III, IV (p=0.047 at day-8, p=0.022 at day-12, p=0.002 at day-18 and p=0.034 at day-21). All mice in Group III died of drug toxicity within two weeks after injection. Group II showed more effective suppression of tumor growth than Group IV (p=0.018 at day-12 and p=0.017 at day-21). Histological analysis showed extensive apoptosis in the TUNEL assay and by Ki -67 staining. Western blotting confirmed strong expression of cleaved caspase-3 in Group II. No significant changes were found hematologically and histologically in the liver, kidney and spleen in Groups I, II, IV but were found in Group III.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.18632/oncotarget.17370DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5522260PMC
June 2017

Role of High-Mobility Group Box 1 (HMGB1) in Transplantation of Rat Pancreatic Islets.

Ann Transplant 2017 Mar 3;22:121-127. Epub 2017 Mar 3.

Laboratory of Stem Cell Biology and Cell Therapy, Asan Institute for Life Science, Asan Medical Center, Seoul, Korea, Democratic People's Republic of.

BACKGROUND The potential role of tissue damage factor high-mobility group box 1 (HMGB1) in islet cell transplantation is poorly understood. We investigated the role of HMGB1 in pancreatic islet cell isolation and culture in vitro and after pancreatic islet cell transplantation into diabetic nude mice in vivo. MATERIAL AND METHODS To generate damaged islets, isolated islets were treated with 1 mg/mL lipopolysaccharide (LPS). Some islets were pretreated with a neutralizing anti-HMGB1 antibody before LPS treatment to investigate the effect of HMGB1 on isolated islets damaged by LPS. Cell viability and insulin secretory function were analyzed 48 h after LPS and anti-HMGB1 antibody treatment. Streptozotocin-induced diabetes mice were injected with an anti-HMGB1 antibody 1 h prior to transplantation as a marginal islet mass. After transplantation, blood glucose levels were measured. RESULTS HMGB1 was more abundant in isolated islets than in other tissues, including pancreatic tissue. Anti-HMGB1 antibody pretreatment in LPS-treated islets improved cell viability and insulin secretory function and reduced the production of TNF-α and IL-1β. Streptozotocin-induced diabetic mice treated with an anti-HMGB1 antibody after marginal mass islet cell transplantation recovered to normal blood glucose levels more rapidly and maintained their euglycemic status compared to controls. CONCLUSIONS HMGB1 plays a significant role in early loss of transplanted islet cells. Based on these results, the development of new drugs that inhibit HMGB1 secretion could improve the efficacy and efficiency of clinical islet cell transplantation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.12659/aot.900731DOI Listing
March 2017

The DPC4/SMAD4 genetic status determines recurrence patterns and treatment outcomes in resected pancreatic ductal adenocarcinoma: A prospective cohort study.

Oncotarget 2017 Mar;8(11):17945-17959

Division of Hepato-Biliary and Pancreatic Surgery, Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.

Objectives: The objective of this study was to investigate the role of genetic status of DPC4 in recurrence patterns of resected pancreatic ductal adenocarcinoma (PDAC).

Methods: Between April 2004 and December 2011, data on patients undergoing surgical resection for PDAC were reviewed. Genetic status of DPC4 was determined and correlated to recurrence patterns and clinical outcomes.

Results: Analysis of 641 patients revealed that genetic status of DPC4 was associated with overall survival and was highly correlated with recurrence patterns, as inactivation of the DPC4 gene was the strongest predictor of metastatic recurrence (odds ratio = 4.28). Treatment modalities for recurrent PDAC included chemotherapy alone and concurrent chemotherapy along with local control. For both locoregional and metastatic recurrence, local control resulted in improved survival; however, for groups subdivided according to recurrence patterns and genetic status of DPC4, local control contributed to improved survival in locoregional recurrences of patients with expressed DPC4, while chemotherapy alone was sufficient for others.

Conclusions: Genetic status of DPC4 contributes to the recurrence patterns following pancreatectomy, and patients with an initially expressed DPC4 gene receive a greater benefit from intensive local control for locoregional recurrence. The DPC4 gene, therefore, may aid the establishment of treatment strategies for initial adjuvant treatment or for recurrent PDAC.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.18632/oncotarget.14901DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5392299PMC
March 2017

The effect of ionized collagen for preventing postoperative adhesion.

J Surg Res 2016 10 5;205(2):341-349. Epub 2016 Jul 5.

Biomedical Engineering Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, South Korea; Department of Surgery, University of Ulsan College of Medicine & Asan Medical Center, Seoul, South Korea. Electronic address:

Background: Collagen exhibits ideal multifactorial action for preventing tissue adhesions. This study examined the efficacy of ionized collagen in preventing tissue adhesion after surgical procedures.

Materials And Method: Ionized collagen was prepared using the esterification technique of natural collagen. Three forms of collagen materials (membrane, film, and gel) were compared with three commercialized materials (oxidized regenerated cellulose membrane [OC membrane], hyaluronic acid and carboxymethylcellulose film, and gel [HC film and HC gel]) in a rat cecum abrasion model. Antiadhesive activity and histologic findings were assessed.

Result: The incidence of adhesion was reduced significantly in all test groups compared to the sham-operated control group (100% in control, 14.3% in collagen membrane, 63.6% in collagen film, 25.0% in collagen gel, 55.6% in OC membrane, 75% in HC film, and 83.3% in HC gel). All collagen materials of the three forms exhibited a significant reduction in adhesion grade compared with the sham operation, whereas no significant difference was found among these three different forms. The collagen membrane showed significantly less adhesion grade, less inflammation and more regenerative features compared to widely used conventional materials.

Conclusions: This preclinical investigation indicated that ionized collagen materials readily formed clinically suitable shapes for easy handling without the need for any complex processing and effectively reduced postoperative tissue adhesion profiles compared to conventional antiadhesive agents.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jss.2016.06.095DOI Listing
October 2016

A 3D-printed local drug delivery patch for pancreatic cancer growth suppression.

J Control Release 2016 09 8;238:231-241. Epub 2016 Jun 8.

Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk, Republic of Korea. Electronic address:

Since recurrence and metastasis of pancreatic cancer has a worse prognosis, chemotherapy has been typically performed to attack the remained malignant cells after resection. However, it is difficult to achieve the therapeutic concentration at the tumor site with systemic chemotherapy. Numerous local drug delivery systems have been studied to overcome the shortcomings of systemic delivery. However, because most systems involve dissolution of the drug within the carrier, the concentration of the drug is limited to the saturation solubility, and consequently cannot reach the sufficient drug dose. Therefore, we hypothesized that 3D printing of a biodegradable patch incorporated with a high drug concentration would provide a versatile shape to be administered at the exact tumor site as well as an appropriate therapeutic drug concentration with a controlled release. Here, we introduce the 3D-printed patches composed of a blend of poly(lactide-co-glycolide), polycaprolactone, and 5-fluorouracil for delivering the anti-cancer drug in a prolonged controlled manner and therapeutic dose. 3D printing technology can manipulate the geometry of the patch and the drug release kinetics. The patches were flexible, and released the drug over four weeks, and thereby suppressed growth of the subcutaneous pancreatic cancer xenografts in mice with minimized side effects. Our approach reveals that 3D printing of bioabsorbable implants containing anti-cancer drugs could be a powerful method for an effective local delivery of chemotherapeutic agents to treatment of cancers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jconrel.2016.06.015DOI Listing
September 2016

Surgical and Oncological Factors Affecting the Successful Engraftment of Patient-derived Xenografts in Pancreatic Ductal Adenocarcinoma.

Anticancer Res 2016 Feb;36(2):517-21

Departments of Surgery, University of Ulsan College of Medicine and Asan Medical Center, Songpa-gu, Seoul, Republic of Korea Asan Institute for Life Sciences, University of Ulsan College of Medicine and Asan Medical Center, Songpa-gu, Seoul, Republic of Korea

Background: To effectively use pancreatic cancer patient-derived xenograft (PDX) models in translational research, successful PDX engraftment of surgical specimens in immune-deficient mice is needed.

Materials And Methods: A total of 102 patients underwent pancreatic cancer resection using various procedures. Tumor tissue from all patents was implanted subcutaneously into mice. Tumor engraftment and growth in mice were determined. Engraftment was tested for correlation with operation type, time, tumor size, and oncogene expression using immunohistoculture.

Results: Multivariate analysis showed that a tumor size of more than 3.5 cm in the patient was a significant factor related to successful PDX engraftment. In contrast, there was no correlation of engraftment with surgical procedure, time needed to remove the specimen, tumor differentiation, lymph node metastasis, and protein expression of p53, Receptor tyrosine-protein kinase erbB-2 (CERBB2), or deleted in pancreatic carcinoma locus 4 (DPC4).

Conclusion: A minimum tumor size in the patient is an important factor for successful tumor engraftment.
View Article and Find Full Text PDF

Download full-text PDF

Source
February 2016

Factors Affecting the Development of Diabetes Mellitus After Pancreatic Resection.

Pancreas 2015 Nov;44(8):1296-303

From the *Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, University of Ulsan College of Medicine and Asan Medical Center; and †Asan Institute for Life Science, Songpa-gu, Seoul, Korea.

Objectives: Glucose homeostasis changes after pancreatic resection are not well understood. We aimed to identify the incidence of, and risk factors for, a change in glucose homeostasis in patients who underwent pancreatectomy for benign pancreatic tumors.

Methods: Clinical and pathological data from 229 patients were collected prospectively and analyzed retrospectively. The pancreas resection volume was calculated by computed tomography volumetry.

Results: After pancreatectomy, newly diagnosed diabetes mellitus (DM) occurred in 52 patients (22.7%) and impaired fasting glucose and impaired glucose tolerance occurred in 74 patients (32.3%). The incidence of DM was highest for patients who underwent distal pancreatectomy (DP) (30.5%). Patients in the DP group had a significantly increased rate of DM as the pancreatic resection volume (in milliliters) and resected volume ratio (in percent) increased. A high body mass index and older age were significant risk factors for the development of DM by multivariate analysis.

Conclusions: The resection volume of the pancreas is associated with a change in glucose homeostasis after pancreatectomy. Therefore, preservation of the pancreatic parenchyma is important to minimize the onset of DM in patients with a high pancreatic resected volume ratio (>35.6%) in DP, a high body mass index, or in old age.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/MPA.0000000000000404DOI Listing
November 2015

Collagen esterification enhances the function and survival of pancreatic β cells in 2D and 3D culture systems.

Biochem Biophys Res Commun 2015 Aug 12;463(4):1084-90. Epub 2015 Jun 12.

Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul, South Korea; Department of Surgery, University of Ulsan College of Medicine & Asan Medical Center, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul, South Korea. Electronic address:

Collagen, one of the most important components of the extracellular matrix (ECM), may play a role in the survival of pancreatic islet cells. In addition, chemical modifications that change the collagen charge profile to a net positive charge by esterification have been shown to increase the adhesion and proliferation of various cell types. The purpose of this study was to characterize and compare the effects of native collagen (NC) and esterified collagen (EC) on β cell function and survival. After isolation by the collagenase digestion technique, rat islets were cultured with NC and EC in 2 dimensional (2D) and 3 dimensional (3D) environments for a long-term duration in vitro. The cells were assessed for islet adhesion, morphology, viability, glucose-induced insulin secretion, and mRNA expression of glucose metabolism-related genes, and visualized by scanning electron microscopy (SEM). Islet cells attached tightly in the NC group, but islet cell viability was similar in both the NC and EC groups. Glucose-stimulated insulin secretion was higher in the EC group than in the NC group in both 2D and 3D culture. Furthermore, the mRNA expression levels of glucokinase in the EC group were higher than those in the NC group and were associated with glucose metabolism and insulin secretion. Finally, SEM observation confirmed that islets had more intact component cells on EC sponges than on NC sponges. These results indicate that modification of collagen may offer opportunities to improve function and viability of islet cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbrc.2015.06.062DOI Listing
August 2015

Biofunctional porous anodized titanium implants for enhanced bone regeneration.

J Biomed Mater Res A 2014 Oct 21;102(10):3639-48. Epub 2013 Nov 21.

Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, South Korea.

Efficient osseointegration is a key factor in dental implants to reduce the total time-course of therapy. Titanium implants with anodized surface gained much interest for their enhanced osseointegration. Anodized implant combined with bioactive drugs is an ideal candidate for enhance bone regeneration. Previously delivery of drugs from the metal implants has been attempted by utilizing a polymeric dip-coating method. However, the entire surface coating with polymer can diminish the advantageous surface roughness of anodized implants and cause contact inhibition between bone and implant surface. In this study, fibroblast growth factor-2 (FGF-2) loaded poly(lactide-co-glycolide) nanoparticles were partially coated on anodized Ti discs by an electrospray deposition. Nanoparticle coated anodized discs maintained their native porous structure and provided a sustained release of FGF-2 for more than 2 weeks with 40% initial burst. In vitro study confirmed the influence of polymeric nanoparticles and the release of growth factors from the Ti disc. Nanoparticle-coated groups significantly enhanced cell spreading and differentiation. For in vivo evaluation, the anodized titanium implants were applied to rabbit tibia model. The osseointegration was estimated by bone to implant contact of best three consecutive threads at the border of the implant. The mean osteointegration value of FGF-2 releasing implant groups (70.1%) was significantly higher than that of untreated implants (47.1%). We believe that the electrospray deposition technique is a particularly attractive approach for the coating of medical devices with porous surface to maintain their surface topography while allowing a sustained delivery of growth factors for bone regeneration. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 3639-3648, 2014.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jbm.a.35026DOI Listing
October 2014

Genetically modified adipose tissue-derived stem/stromal cells, using simian immunodeficiency virus-based lentiviral vectors, in the treatment of hemophilia B.

Hum Gene Ther 2013 Mar;24(3):283-94

Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, Tokyo, Japan.

Hemophilia is an X-linked bleeding disorder, and patients with hemophilia are deficient in a biologically active coagulation factor. This study was designed to combine the efficiency of lentiviral vector transduction techniques with murine adipose tissue-derived stem/stromal cells (mADSCs) as a new method to produce secreted human coagulation factor IX (hFIX) and to treat hemophilia B. mADSCs were transduced with simian immunodeficiency virus (SIV)-hFIX lentiviral vector at multiplicities of infection (MOIs) from 1 to 60, and the most effective dose was at an MOI of 10, as determined by hFIX production. hFIX protein secretion persisted over the 28-day experimental period. Cell sheets composed of lentiviral vector-transduced mADSCs were engineered to further enhance the usefulness of these cells for future therapeutic applications in transplantation modalities. These experiments demonstrated that genetically transduced ADSCs may become a valuable cell source for establishing cell-based gene therapies for plasma protein deficiencies, such as hemophilia.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1089/hum.2012.162DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3609603PMC
March 2013

Local BMP-7 release from a PLGA scaffolding-matrix for the repair of osteochondral defects in rabbits.

J Control Release 2012 Sep 6;162(3):485-91. Epub 2012 Aug 6.

Department of Pharmacy, Ewha Womans University, 11-1 Daehyun-dong, Seodaemun-gu, Seoul 120-750, Republic of Korea.

The use of tissue engineering to repair large osteochondral defects has been impeded by the limited regenerative capacity of cartilage. Herein, we describe the local release of bone morphogenetic protein 7 (BMP-7) to stimulate the bone marrow-derived progenitors to repair osteochondral defects. BMP-7-releasing poly(D,L-lactide-co-glycolide) (PLGA) matrix was specially designed to retain the dual-function of local BMP-7 release and progenitor-scaffolding with its defect-fitting architecture. To optimize the release kinetics during the repair period, BMP-7/PLGA film was cast on the surface of a cylindrical PLGA matrix. The matrix demonstrated a release profile of BMP-7 in a sustained manner over 28 days, maintaining its biological activity. The cylindrical PLGA matrices loaded with BMP-7 were implanted into the osteochondral defects (2 mm in diameter, 3 mm in depth) in rabbit knees. Histological observations revealed that neo-cartilage generation was completed in a well-integrated morphology with its surrounding normal cartilage and subchondral bone at 12 weeks post-implantation. Partial degradation of the PLGA matrix during the repair period guided neo-cartilage formation, which verified the effective scaffolding function of the matrix. Regenerated cartilage in BMP-7-treated defects stained positive for type II collagen and glycosaminoglycan (GAG). Adjacent BMP-7-untreated defects were also repaired with cartilage regeneration, suggesting the effect of local BMP-7 release in the synovial fluid. The BMP-7-unloaded PLGA matrix demonstrated guided cartilage regeneration to a certain extent, whereas the adjacent defects without the matrix revealed only fibrous tissue infiltration. These results indicated that a strategy employing the combined functions of local BMP-7 release and the cell scaffolding of a PLGA matrix might be a potential modality for osteochondral repair.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jconrel.2012.07.040DOI Listing
September 2012

Controlled release of cell-permeable gene complex from poly(L-lactide) scaffold for enhanced stem cell tissue engineering.

J Control Release 2011 Jun 21;152(2):294-302. Epub 2011 Mar 21.

Department of Pharmacy, Ewha Womans University, Daehyun-dong, Seodaemun-gu, Seoul 120-750, Republic of Korea.

The use of tissue engineering to deliver genes to stem cells has been impeded by low transfection efficiency of the inserted gene and poor retention at the target site. Herein, we describe the use of non-viral gene transfer by cell-permeable peptide (CPP) to increase the transfection efficiency. The combination of this technique with the use of a controlled release concept using a poly (l-lactide) scaffold allowed for prolonged uptake in stem cells. High transfection efficiency was obtained using a human-derived arginine-rich peptide denoted as Hph-1 (YARVRRRGPRR). The formation of complex between pDNA and Hph-1 was monitored using gel retardation tests to measure size and zeta potential. Complex formation was further assessed using a DNase I protection assay. A sustained gene delivery system was developed using a fibrous 3-D scaffold coated with pDNA/Hph-1 complexes. Transfection efficiency and the mean fluorescence intensity of human adipose-derived stem cells (hASCs) on the sustained delivery scaffold were compared to those of cells transfected via bolus delivery. Plasmid DNA completely bound Hph-1 at a negative-to-positive (N/P) charge ratio of 10. After complex formation, Hph-1 appeared to effectively protect pDNA against DNase I attack and exhibited cytotoxicity markedly lower than that of the pDNA/PEI complex. Plasmid DNA/Hph-1 complexes were released from the scaffolds over 14days and were successfully transfected hASCs seeded on the scaffolds. Flow cytometry revealed that the transfection efficiency in hASCs treated with pDNA/Hph-1 complex was approximately 5-fold higher than that in cells transfected using Lipofectamine. The sustained delivery system showed a significantly higher transfection efficiency and remained able to transfect cells for a longer period of time than bolus delivery. These results suggest that cell-scaffold-based tissue regeneration can be further improved by transduction concept using CPP and controlled release using polymeric scaffold.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jconrel.2011.03.002DOI Listing
June 2011

Novel three-dimensional scaffolds of poly(L-lactic acid) microfibers using electrospinning and mechanical expansion: Fabrication and bone regeneration.

J Biomed Mater Res B Appl Biomater 2010 Oct;95(1):150-60

Department of Pharmacy, College of Pharmacy, Ewha Womans University, Seodaemun-gu, Seoul 120-750, Korea.

Poly(L-lactic acid) (PLLA) microfibrous scaffolds with three-dimensional (3D) structures were fabricated using an electrospinning technique with a subsequent mechanical expansion process. To achieve a 3D fibrous structure, the fusion at the contact points of the as-spun PLLA microfibers was avoided using an appropriate binary solvent system of methylene chloride and acetone. The solvent composition was optimized based on the solvent power, volatility, and viscosity (methylene chloride:acetone = 9:1 volume ratio). The final 3D structure of the electrospun scaffolds was obtained after mechanical expansion of the electrospun microfibrous mats. The pore sizes of the scaffolds were controlled by varying the degree of expansion of the nonbonded microfibrous mats, and they were in the range of several microns up to 400 μm. The 3D scaffolds were examined for their morphological properties and their potential use for the proliferation of osteoblasts. Generally recognized electrospun 2D nanofibrous membranes were also tested in order to compare the cell behaviors using different scaffold geometries. The 3D scaffolds demonstrated a high level of osteoblast proliferation (1.8-fold higher than nanofibrous membranes in a week). The osteoblasts actively penetrated the inside of the 3D scaffold and showed a spatial cell distribution, as confirmed by SEM and H&E staining, while a monolayer formed in the case of the 2D nanofibrous membranes with limited cell infiltration. In vivo results further showed that 3D electrospun microfibrous matrices were a favorable substrate for cell infiltration and bone formation after 2 and 4 weeks, using a rabbit calvarial defect model. In this study, the 3D microfibrous PLLA scaffolds fabricated using electrospinning techniques might be an innovative addition to tissue engineering applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jbm.b.31695DOI Listing
October 2010

Troglitazone enhances tamoxifen-induced growth inhibitory activity of MCF-7 cells.

Biochem Biophys Res Commun 2008 Dec 7;377(1):242-7. Epub 2008 Oct 7.

Department of Biochemistry, Institute for Medical Sciences, Chonbuk National University Medical School, Jeonju, Jeonbuk, Republic of Korea.

Peroxisome proliferator-activated receptor gamma (PPARgamma) ligands have been identified as a potential source of therapy for human cancers. However, PPARgamma ligands have a limitation for breast cancer therapy, since estrogen receptor alpha (ER(alpha)) negatively interferes with PPARgamma signaling in breast cancer cells. Here we show that ER(alpha) inhihits PPARgamma transactivity and ER(alpha)-mediated inhibition of PPARgamma transactivity is blocked by tamoxifen, an estrogen receptor blocker. The activation of ER(alpha) with 17-beta-estradiol blocked PPRE transactivity induced by troglitazone, a PPARgamma ligand, indicating the resistance of ER(alpha)-positive breast cancer cells to troglitazone. Indeed, troglitazone inhibited the growth of ER(alpha)-negative MDA-MB-231 cells more than that of ER(alpha)-positive MCF-7 cells. Combination of troglitazone with tamoxifen led to a marked increase in growth inhibition of ER(alpha)-positive MCF-7 cells compared to either agent alone. Our data indicates that troglitazone enhances the growth inhibitory activity of tamoxifen in ER(alpha)-positive MCF-7 cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbrc.2008.09.111DOI Listing
December 2008

Chitosan/poly(L-lactic acid) multilayered membrane for guided tissue regeneration.

J Biomed Mater Res A 2009 Sep;90(3):766-72

Department of Periodontology, College of Dentistry, Seoul National University, 28-2 Yongon-Dong, Chongno-Ku, Seoul 110-749, South Korea.

A chitosan/poly(L-lactic acid) (PLLA) multilayered membrane was prepared for the purpose of guided tissue regeneration (GTR). The membrane was composed of the outer layers of chitosan mesh and the middle layer of nanoporous PLLA membrane. The outer membranes of chitosan fibrous mesh present a highly biocompatible and rough surface for ease of cell adherence. The PLLA membrane is intended to provide mechanical strength to the membrane, thereby preventing epithelial invasion. The PLLA membrane was applied as a local drug delivery carrier for growth factors. Regular pores in PLLA membrane were generated through phase inversion of polymer solution. The membrane retained its integrity during the degradation process in vitro (for up to 8 weeks), which is a requirement for providing enough space in vivo in the GTR procedure. Osteoblasts firmly attached to broad cytoplasmic extensions along with the microfibers of the membrane. The phenotypic expression of cultured osteoblasts on the membrane was measured by a reverse transcriptase-polymerase chain reaction. New bone had formed beneath the chitosan/PLLA membrane. These results suggested that the chitosan/PLLA membranes properly functioned as biocompatible and mechanically stable barriers for GTR.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jbm.a.31846DOI Listing
September 2009
-->