Seung-Pyo Lee

Integrin-Linked Kinase, a Hypoxia-Responsive Molecule, Controls Postnatal Vasculogenesis by Recruitment of Endothelial Progenitor Cells to Ischemic Tissue

Background— Recruitment and adhesion of endothelial progenitor cells (EPCs) to hypoxic endothelial cells (ECs) is essential for vasculogenesis in ischemic tissue; little is known, however, about the key signals or intracellular signaling pathways involved in orchestrating the expression of adhesion molecules by ECs in response to hypoxia and how this is related to the recruitment of EPCs to the ischemic tissue. Here, we report that endogenous integrin-linked kinase (ILK) is a novel molecule that responds to hypoxia in ECs that regulates the expression of stromal cell–derived factor-1 (SDF-1) and intercellular adhesion molecule-1 (ICAM-1) through nuclear factor-&kgr;B and hypoxia-inducible factor-1α and induces recruitment of EPCs to ischemic areas. Methods and Results— Under hypoxia, both the endogenous amount and kinase activity of ILK were time-dependently upregulated in ECs, which was associated with increased ICAM-1 and SDF-1. This upregulation of ILK was mediated by stabilization of ILK by heat shock protein 90. ILK overexpression in normoxic ECs resulted in ICAM-1 and SDF-1 upregulation through dual control by nuclear factor-&kgr;B and hypoxia-inducible factor-1α. Blockade of ILK in hypoxic ECs significantly abrogated the expression of both molecules, which led to decreased EPC incorporation into ECs. A hindlimb ischemia model showed that ILK blockade significantly reduced EPC homing to ischemic limb and consequently led to poor neovascularization. Overexpression of ILK in the Matrigel plug significantly improved neovascularization in vivo, whereas the blockade of ILK resulted in the opposite effect. Conclusions— Endogenous ILK is a novel and physiological upstream responder of numerous intracellular molecules involved in hypoxic stress in ECs and may control the recruitment of EPCs to ischemic tissue.

Human mesenchymal stem cell-derived Schwann cell-like cells exhibit neurotrophic effects, via distinct growth factor production, in a model of spinal cord injury

Human bone marrow‐derived mesenchymal stem cells (hMSCs) are considered a desirable cell source for autologous cell transplantation therapy to treat nervous system injury due to their ability to differentiate into specific cell types and render the tissue microenvironment more favorable for tissue repair by secreting various growth factors. To potentiate their possible trophic effect, hMSCs were induced without genetic modification to adopt characteristics of Schwann cells (SCs), which provide trophic support for regenerating axons. The induced hMSCs (shMSCs) adopted a SC‐like morphology and expressed SC‐specific proteins including the p75 neurotrophin receptor, which correlated with cell‐cycle exit. In addition, shMSCs secreted higher amounts of several growth factors, such as hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) when compared with uninduced hMSCs. Coculture of shMSCs with Neuro2A cells significantly increased neurite outgrowth and cell proliferation but decreased cell death. Transplantation of shMSCs in an ex vivo model of spinal cord injury dramatically enhanced axonal outgrowth, which was mediated by HGF and VEGF secretion and also decreased cell death. These results demonstrate that shMSCs could serve as an endogenous source of neurotrophic growth factors to facilitate axonal regeneration while at the same time protecting the resident cells at the site of tissue injury. We propose that these induced hMSCs without genetic modification are useful for autologous cell therapy to treat nervous system injury.

A multicenter, phase II trial of everolimus in locally advanced or metastatic thyroid cancer of all histologic subtypes

BACKGROUND This phase II study investigated the efficacy and safety of everolimus, an inhibitor of mammalian target of rapamycin (mTOR), in locally advanced or metastatic thyroid cancer. PATIENTS AND METHODS Patients with thyroid cancer of any histology that was resistant or not appropriate for (131)I received everolimus 10 mg daily orally until unacceptable toxicity or disease progression. The primary end point was disease control rate [partial response (PR) + stable response ≥12 weeks]. Secondary end points included response rates, clinical benefit (PD + durable stable disease (SD)], progression-free survival (PFS), overall survival, duration of response, and safety. RESULTS Thirty-eight of 40 enrolled patients were evaluable for efficacy. The disease control rate was 81% and two (5%) patients achieved objective response; their duration of response was 21+ and 24+ weeks. Stable disease (SD) and progressive disease was reported in 76% and 17% of patients, respectively. Seventeen (45%) patients showed durable SD (≥24 weeks) and clinical benefit was reported in 19 (50%) patients. Median PFS was 47 weeks [95% confidence interval (CI) 14.9-78.5]. Calcitonin, CEA, and thyroglobulin concentrations were ≥50% lower than baseline in three (30%) and four (44%) patients with medullary thyroid cancer and five (33%) patients with PTC, respectively. The most common treatment-related adverse events were mucositis (84%), anorexia (44%), and aspartate transaminase/alanine transaminase elevation (26%). CONCLUSIONS Everolimus had a limited activity with low response rate in locally advanced or metastatic thyroid cancer. Reasonable clinical benefit rate and safety profile may warrant further investigation. CLINICALTRIALSGOV NUMBER NCT01164176.

Unicameral bone cysts

Open surgery is rarely justified for the initial treatment of a unicameral bone cyst, but there is some debate concerning the relative effectiveness of closed methods. This study compared the results of steroid injection with those of autologous bone marrow grafting for the treatment of unicameral bone cysts. Between 1990 and 2001, 30 patients were treated by steroid injection and 28 by grafting with autologous bone marrow. The overall success rates were 86.7% and 92.0%, respectively (p>0.05). The success rate after the initial procedure was 23.3% in the steroid group and 52.0% in those receiving autologous bone marrow (p<0.05), and the respective cumulative success rates after second injections were 63.3% and 80.0% (p>0.05). The mean number of procedures required was 2.19 (1 to 5) and 1.57 (1 to 3) (p<0.05), the mean interval to healing was 12.5 months (4 to 32) and 14.3 months (7 to 36) (p>0.05), and the rate of recurrence after the initial procedure was 41.7% and 13.3% in the steroid and in the autologous bone marrow groups, respectively (p<0.05). Although the overall rates of success of both methods were similar, the steroid group had higher recurrence after a single procedure and required more injections to achieve healing.

Cilostazol attenuates on-treatment platelet reactivity in patients with CYP2C19 loss of function alleles receiving dual antiplatelet therapy: a genetic substudy of the CILON-T randomised controlled trial

Objective To evaluate whether the addition of cilostazol to dual antiplatelet therapy (DAT, aspirin plus clopidogrel) can attenuate clopidogrel on-treatment platelet reactivity (OPR) in patients with the CYP2C19 loss-of-function (LOF) allele. Methods In the CILON-T randomised trial, patients were randomly assigned to either DAT or triple antiplatelet therapy (TAT, DAT plus cilostazol). Genotyping of cytochrome P450 CYP2C19 *2, *3 and *17 was performed and OPR was measured using the VerifyNow P2Y12 assay. Carriers were those with at least one CYP2C19 LOF allele. Results 474 patients were enrolled; 236 received DAT, 238 TAT. Mean OPR was significantly lower in the TAT compared with the DAT group (207±5 vs 236±5, p<0.001, P2Y12 reaction units, PRU). When grouped according to the presence of the CYP2C19 LOF allele, mean OPR was significantly lower in the TAT compared with the DAT group in only carriers of the LOF allele and not non-carriers (213±6 vs 256±7 PRU, p<0.001 in carriers, 196±9 vs 211±8 PRU, p=0.242 in non-carriers for TAT vs DAT, respectively). The proportion of patients with high OPR was highest in carriers receiving DAT (60.8%) compared with the other three groups. On multivariate analysis, carriers on DAT was an independent predictor of high OPR (OR 2.93, 95% CI 1.64 to 5.21) along with female gender and increasing age. Conclusion TAT significantly reduced OPR compared with DAT in carriers of the CYP2C19 LOF allele, but not in non-carriers. These data suggest that the addition of cilostazol to DAT may be a good strategy to attenuate CYP2C19 LOF-related high OPR.

Minimization of Immunosuppressive Therapy After Islet Transplantation: Combined Action of Heme Oxygenase‐1 and PEGylation to Islet

We previously established a type of PEGylated islets to attenuate cellular immune reactions by immobilizing polyethylene glycol (PEG) molecules on islet surfaces, thereby synergistically reducing the dose of immunosuppressant cyclosporine A (CsA; 3 mg/kg/day) to protect transplanted islets. However, higher doses of immunosuppressants should be administered after islet transplantation due to nonspecific inflammation. This study documents that PEGylated islets can be cooperatively protected by the systemic overexpression of heme oxygenase‐1 (HO‐1), which has a potent cytoprotective function in preventing nonspecific inflammation during an early stage following islet transplantation. Under this scheme, the viability of PEGylated islets was improved; that is, PEG molecules could block cellular immunity and HO‐1 could exert its cytoprotective property against inflammation. Interestingly, when employed with a low dose of CsA (1 mg/kg/day), a cooperative action of PEG molecules and HO‐1 in immune reactions could result in the complete survival of transplanted islets for 100 days without islet function impairment. However, unmodified islets (control) were completely rejected within 2 weeks despite cotreatment with HO‐1 expression and CsA. These results demonstrated that the combinatorial protocol of initial induction of HO‐1 expression, followed by the daily administration of a low dose CsA after transplantation of PEGylated islets can be employed as a successful cell therapy in clinical islet transplantation.

The in vitro effects of dehydroepiandrosterone on human osteoarthritic chondrocytes

OBJECTIVE To investigate the in vitro effects of dehydroepiandrosterone (DHEA) on human osteoarthritic chondrocytes. DESIGN Chondrocytes isolated from human osteoarthritic knee cartilage were three-dimensionally cultured in alginate beads, except for cell proliferation experiment. Cells were treated with DHEA in the presence or absence of IL-1beta. The effects on chondrocytes were analyzed using a 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay (for chondrocyte proliferation), a dimethylmethylene blue (DMB) assay (for glycosaminoglycan (GAG) synthesis), and an indole assay (for DNA amount). Gene expressions of type I and II collagen, metalloproteinase-1 and -3 (MMP-1 and -3), and tissue inhibitor of metalloproteinase-1 (TIMP-1) as well as the IL-1beta-induced gene expressions of MMP-1 and -3 were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The protein synthesis of MMP-1 and -3 and TIMP-1 was determined by Western blotting. RESULTS The treatment of chondrocytes with DHEA did not affect chondrocyte proliferation or GAG synthesis up to 100 micro M of concentration. The gene expression of type II collagen increased in a dose-dependent manner, while that of type I decreased. DHEA suppressed the expression of MMP-1 significantly at concentrations exceeding 50 micro M. The gene expression of MMP-3 was also suppressed, but this was without statistical significance. The expression of TIMP-1 was significantly increased by DHEA at concentrations exceeding 10 micro M. The effects of DHEA on the gene expressions of MMP-1 and -3 were more prominent in the presence of IL-1beta, in which DHEA suppressed not only MMP-1, but also MMP-3 at the lower concentrations, 10 and 50 micro M, respectively. Western blotting results were in agreement with RT-PCR, which indicates that DHEA acts at the gene transcription level. CONCLUSIONS Our study demonstrates that DHEA has no toxic effect on chondrocytes up to 100 micro M of concentration and has an ability to modulate the imbalance between MMPs and TIMP-1 during OA at the transcription level, which suggest that it has a protective role against articular cartilage loss.

Surface Characteristics of Orthodontic Materials and Their Effects on Adhesion of Mutans streptococci

OBJECTIVE To test the hypothesis that there are no significant differences in the adhesion of mutans streptococci (MS) to various orthodontic materials based on their surface characteristics. MATERIALS AND METHODS Surface roughness (SR) and surface free energy (SFE) characteristics were investigated for nine different orthodontic materials (four orthodontic adhesives, three bracket raw materials, hydroxyapatite blocks, and bovine incisors) using confocal laser scanning microscopy and sessile drop method. Each material, except the bovine incisors, was incubated with whole saliva or phosphate-buffered saline for 2 hours. Adhesion assays were performed by incubating tritium-labeled MS with each material for 3 or 6 hours. RESULTS Orthodontic adhesives had higher SFE characteristics and lower SR than bracket materials. Orthodontic adhesives showed a higher MS retaining capacity than bracket materials, and MS adhesion to resin-modified glass ionomer and hydroxyapatite was highest. Extended incubation time increased MS adhesion, while saliva coating did not significantly influence MS adhesion. SFE, specifically its dispersive and polar components, was positively correlated with MS adhesion, irrespective of saliva coating. CONCLUSIONS The hypothesis is rejected. This study suggests that SFE characteristics play an important role in the initial MS adhesion to orthodontic materials.

Comparative crash simulations incorporating the results of sheet forming analyses

To obtain more reliable crash simulations the history of the structure related to the forming process is considered. For this goal the variables defining the current state have to be transferred from one mesh to the other in order to maintain a consistent discretization of the whole structure consisting of several pre‐formed parts. This is accomplished here by remeshing the structure after the forming process and by transferring the current mechanical properties. In performing such a transfer a numerical error cannot be avoided; the results of this approach are therefore compared with computations in which this transfer is not applied to assess the performance of the presented procedure.

Three-dimensional analysis of the tooth movement and arch dimension changes in Class I malocclusions treated with first premolar extractions: a guideline for virtual treatment planning.

INTRODUCTION Our objective was to analyze patterns of tooth movement and changes of arch dimension by superimposing 3-dimensional (3D) virtual models. METHODS The sample consisted of 24 Korean adults with Class I malocclusion and minimal crowding, treated by first premolar extractions, sliding mechanics (0.022-in MBT brackets [3M Unitek, Monrovia, Calif] with 0.019 × 0.025-in stainless steel wire) and moderate anchorage. The 3D virtual maxillary casts at pretreatment and posttreatment were superimposed with the best-fit method. Linear and angular variables were measured with 3Txer program (Orapix, Seoul, Korea). Wilcoxon signed rank and Mann-Whitney tests were used for statistical analysis. RESULTS There was no significant difference in the individual tooth movement between the right and left sides (P > 0.05). For the movement of each tooth, the maxillary central incisors (U1), lateral incisors (U2), and canines (U3) were significantly inclined lingually, extruded, and moved posteriorly and laterally. The maxillary second premolar (U5), first molar (U6), and second molar (U7) had significant mesial inward rotation, anterior movement, and contracted toward the midsagittal plane. The ratio of anteroposterior movement between the maxillary anterior and posterior teeth was 5:1. The amounts of contraction in U5, U6, and U7 were 1.4, 1.3, and 1.2 mm, respectively. When the amount of change between the adjacent teeth were compared, the linguoversion in U1 was significantly greater than that of U2. U3 and U5 showed significant opposite movements in all variables. There were differences only in angulation and vertical displacement between U6 and U7. CONCLUSIONS Superimposition of 3D virtual models could be a guideline for precise virtual treatment planning.