Browsing by Subject "regeneration"
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Item Conference Report: 6th Annual International Symposium on Regenerative Rehabilitation(Future Medicine, 2018-06) Loghmani, M. Terry; Roche, Joseph A.; Physical Therapy, School of Health and Human SciencesThe 6th International Symposium on Regenerative Rehabilitation, hosted by the Alliance for Regenerative Rehabilitation Research and Training (AR3T), included a preconference meeting of institutional representatives of the International Consortium of Regenerative Rehabilitation, keynote talks from distinguished scientists, platform and poster presentations from experts and trainees, panel discussions and postconference workshops. The following priorities were identified: increasing rigor in basic, preclinical and clinical studies, especially the use of better controls; developing better outcome measures for preclinical and clinical trials; focusing on developing more tissue-based interventions versus cell-based interventions; including regenerative rehabilitation in curricula of professional programs like occupational and physical therapy; and developing better instruments to quantify rehabilitative interventions.Item The Direct Reprogramming of Somatic Cells: Establishment of a Novel System for Photoreceptor Derivation(2013-08-22) Steward, Melissa Mary; Meyer, Jason S.; Dai, Guoli; Randall, Stephen Karl, 1953-; Atkinson, SimonPhotoreceptors are a class of sensory neuronal cells that are deleteriously affected in many disorders and injuries of the visual system. Significant injury or loss of these cells often results in a partial or complete loss of vision. While previous studies have determined many necessary components of the gene regulatory network governing the establishment, development, and maintenance of these cells, the necessary and sufficient profile and timecourse of gene expression and/or silencing has yet to be elucidated. Arduous protocols do exist to derive photoreceptors in vitro utilizing pluripotent stem cells, but only recently have been able to yield cells that are disease- and/or patient-specific. The discovery that mammalian somatic cells can be directly reprogrammed to another terminally-differentiated cell phenotype has inspired an explosion of research demonstrating the successful genetic reprogramming of one cell type to another, a process which is typically both more timely and efficient than those used to derive the same cells from pluripotent stem cell sources. Therefore, the emphasis of this study was to establish a novel system to be used to determine a minimal transcriptional network capable of directly reprogramming mouse embryonic fibroblasts (MEFs) to rod photoreceptors. The tools, assays, and experimental design chosen and established herein were designed and characterized to facilitate this determination, and preliminary data demonstrated the utility of this approach for accomplishing this aim.Item The effect of triple antibiotic paste and EDTA on the surface loss and surface roughness of radicular dentin(2014) Nerness, Andrew; Spolnik, Kenneth Jacob, 1950-; Zunt, Susan L., 1951-; Platt, Jeffrey A., 1958-; Ehrlich, YgalIntroduction: Regenerative endodontic therapy in immature teeth with necrotic pulps triggers continued root development thereby improving the prognosis of these teeth. Several agents are under consideration for the disinfection and conditioning phases of this therapy. Triple antibiotic paste (TAP, i.e. equal parts of ciprofloxacin, metronidazole, minocycline) is used for canal disinfection and 17% EDTA solution is used for dentin conditioning. However, TAP and EDTA cause demineralization and their effect on surface loss and surface roughness of radicular dentin during regenerative procedures has not been quantified. Surface loss may be correlated with reduced tooth strength and surface roughness may be correlated with stem cell attachment. Objectives: The aim of this in vitro study was to quantitatively investigate the surface loss and surface roughness on human radicular dentin after treatment with two concentrations of TAP followed by EDTA. Materials and Methods: Human radicular dentin specimens were prepared from extracted human anterior teeth and randomized into six experimental groups. Group 1: saline control; Group 2: 17% EDTA; Group 3: TAP 1 mg/mL; Group 4: TAP 1 mg/mL and 17% EDTA; Group 5: TAP 1,000 mg/mL; Group 6: TAP 1,000 mg/mL and 17% EDTA for 5 minutes. After TAP is applied to Groups 3-6, all groups were incubated for 4 weeks. Then, groups 2, 4, and 6 were treated with EDTA for 5 minutes. Dentin surface loss (μm) and surface roughness (Ra, μm) were quantified after various treatments using non-contact and contact profilometry, respectively. Data were analyzed by one-way analysis of variance (α = 0.05) Hypothesis: It was hypothesized that there would be a significant difference in surface loss or surface roughness between at least two treatment groups. Results: All treatment groups showed significantly higher surface loss compared to untreated control. Dentin treated with 1g/mL TAP caused significant increase in surface loss and surface roughness compared to dentin treated with 1 mg/mL TAP. However, only 1g/mL TAP treated dentin showed significantly higher surface roughness compared to untreated control. The use of EDTA after both concentrations of TAP did not have significant additive effect on surface loss and surface roughness of dentin. Conclusion: The use of 1 mg/mL TAP can minimize surface loss and surface roughness of radicular dentin compared to higher concentrations. The use of EDTA after TAP may not cause additional surface loss and surface roughness of dentin.Item The Effects of Nano-Hydroxyapatite in a Double Antibiotic Paste-Loaded Methycellulose Carrier on Dental Pulp Stem Cells(2019) Everhart, Adam R.; Spolnik, Kenneth J.; Bruzzaniti, Angela; Bringas, Josef S.; Ehrlich, Ygal; Gregory, Richard L.The effects of hydroxyapatite in a DAP-loaded MC carrier on dental pulp stem cells Introduction: Regenerative endodontic procedures (REP) require disinfection techniques to eliminate bacteria from the infected immature root canal system and promote new growth of the pulp-dentin complex. Double antibiotic paste (DAP), a mixture of ciprofloxacin and metronidazole, has shown efficacy in doing so while minimizing cytotoxicity on dental pulp stem cells (DPSC). Stem cells, scaffolding, and growth factors are necessary in the maturation, proliferation, and differentiation of mesenchymal stem cells into the root canal system. Nano-hydroxyapatite (n-HA) has a history of biocompatibility and, in addition, has shown promising effects as a tissue bioengineering material. Objective: The aim of this in vitro study was to investigate the proliferation and mineralization of DPSC in the presence of 1% DAP and methylcellulose (MC) with varying concentrations of nano-hydroxyapatite. Materials and Methods: DPSC were plated in 24-well plates containing culture media. The next day, semi-permeable 0.1 mm Transwell chambers were inserted into the wells to separate the reservoirs for medicaments. Treatment paste composed of methylcellulose containing 1% DAP with either 0.25%, 0.50%, or 1.0% nano-hydroxyapatite was added along with culture media. Methylcellulose alone and calcium hydroxide (Ultracal) were used as control groups. After 3 days, cells were evaluated for cytotoxic effects using an MTS proliferation assay (n = 10, in triplicate). DPSCs were also cultured with these medicaments for 7 days in osteogenic media and evaluated for alkaline phosphatase (ALP) activity and mineralization activity (n = 13, in triplicate). Comparisons between groups for differences in mineralization, BSA, and ALP activity were performed using analysis of variance (ANOVA), with different variances allowed for each group and a random effect included in the model to account for correlation within each of the three trials. A simulation-based model was used to adjust for multiple comparisons. Results: Addition of n-HA treatment groups increased mineralization significantly greater than calcium hydroxide, with MC alone and MC+DAP+0.5% HA providing the greatest effect. Regarding ALP, all HA concentrations performed significantly greater than MC and DAP concentrations. Proliferation demonstrated similar metabolic activity in all experimental groups with few comparisons significant. Conclusion: The challenge in REPs is to maintain survival, and preferably promote the proliferation and development of DPSCs into the pulp-dentin complex with a consistent treatment outcome. The combination of DAP with hydroxyapatite may allow for both disinfection and improved mineralization and cellular differentiation. This contribution has shown significant ability to increase stem cell differentiation into an osteogenic lineage as well as calcium deposition, indicating end goal results of regenerative procedures.Item Mechanisms of Urodele Limb Regeneration(Wiley, 2017) Stocum, David L.; Biology, School of ScienceThis review explores the historical and current state of our knowledge about urodele limb regeneration. Topics discussed are (1) blastema formation by the proteolytic histolysis of limb tissues to release resident stem cells and mononucleate cells that undergo dedifferentiation, cell cycle entry and accumulation under the apical epidermal cap. (2) The origin, phenotypic memory, and positional memory of blastema cells. (3) The role played by macrophages in the early events of regeneration. (4) The role of neural and AEC factors and interaction between blastema cells in mitosis and distalization. (5) Models of pattern formation based on the results of axial reversal experiments, experiments on the regeneration of half and double half limbs, and experiments using retinoic acid to alter positional identity of blastema cells. (6) Possible mechanisms of distalization during normal and intercalary regeneration. (7) Is pattern formation is a self-organizing property of the blastema or dictated by chemical signals from adjacent tissues? (8) What is the future for regenerating a human limb?Item A novel patient-specific three-dimensional drug delivery construct for regenerative endodontics(Wiley, 2018-10-03) Bottino, Marco C.; Albuquerque, Maria T. P.; Azabi, Asma; Münchow, Eliseu A.; Spolnik, Kenneth J.; Nör, Jacques E.; Edwards, Paul C.; Oral Pathology, Medicine and Radiology, School of DentistryEvoked bleeding (EB) clinical procedure, comprising a disinfection step followed by periapical tissue laceration to induce the ingrowth of undifferentiated stem cells from the periodontal ligament and alveolar bone, is currently the only regenerative-based therapeutic approach to treating pulp tissue necrosis in undeveloped (immature) permanent teeth approved in the United States. Yet, the disinfection step using antibiotic-based pastes leads to cytotoxic, warranting a biocompatible strategy to promote root canal disinfection with no or minimal side-effects to maximize the regenerative outcomes. The purpose of this investigation was to develop a tubular three-dimensional (3D) triple antibiotic-eluting construct for intracanal drug delivery. Morphological (scanning electron microscopy), chemical (Fourier transform infrared spectroscopy), and mechanical (tensile testing) characteristics of the polydioxanone-based triple antibiotic-eluting fibers were assessed. The antimicrobial properties of the tubular 3D constructs were determined in vitro and in vivo using an infected (Actinomyces naeslundii) dentin tooth slice model and a canine method of periapical disease, respectively. The in vitro data indicated significant antimicrobial activity and the ability to eliminate bacterial biofilm inside dentinal tubules. In vivo histological findings demonstrated that, using the EB procedure, the tubular 3D triple antibiotic-eluting construct allowed the formation of an appropriate environment that led to apex closure and the ingrowth of a thin layer of osteodentin-like tissue into the root canal. Taken together, these findings indicate that our novel drug delivery construct is a promising biocompatible disinfection strategy for immature permanent teeth with necrotic pulps.Item Targeting polyamine biosynthesis to stimulate beta cell regeneration in zebrafish(Taylor & Francis, 2020-07-25) Robertson, Morgan A.; Padgett, Leah R.; Fine, Jonathan A.; Chopra, Gaurav; Mastracci, Teresa L.; Biology, School of ScienceType 1 diabetes (T1D) is a disease characterized by destruction of the insulin-producing beta cells. Currently, there remains a critical gap in our understanding of how to reverse or prevent beta cell loss in individuals with T1D. Previous studies in mice discovered that pharmacologically inhibiting polyamine biosynthesis using difluoromethylornithine (DFMO) resulted in preserved beta cell function and mass. Similarly, treatment of non-obese diabetic mice with the tyrosine kinase inhibitor Imatinib mesylate reversed diabetes. The promising findings from these animal studies resulted in the initiation of two separate clinical trials that would repurpose either DFMO (NCT02384889) or Imatinib (NCT01781975) and determine effects on diabetes outcomes; however, whether these drugs directly stimulated beta cell growth remained unknown. To address this, we used the zebrafish model system to determine pharmacological impact on beta cell regeneration. After induction of beta cell death, zebrafish embryos were treated with either DFMO or Imatinib. Neither drug altered whole-body growth or exocrine pancreas length. Embryos treated with Imatinib showed no effect on beta cell regeneration; however, excitingly, DFMO enhanced beta cell regeneration. These data suggest that pharmacological inhibition of polyamine biosynthesis may be a promising therapeutic option to stimulate beta cell regeneration in the setting of diabetes.Item Triple Antibiotic Polymer Nanofibers for Intracanal Drug Delivery: Effects on Dual Species Biofilm and Cell Function(Elsevier, 2016-10) Pankajakshan, Divya; Albuquerque, Maria T.P.; Evans, Joshua D.; Kamocka, Malgorzata M.; Gregory, Richard L.; Bottino, Marco C.; Biomedical and Applied Sciences, School of DentistryIntroduction Root canal disinfection and the establishment of an intracanal microenvironment conducive to the proliferation/differentiation of stem cells play a significant role in regenerative endodontics. This study was designed to (1) investigate the antimicrobial efficacy of triple antibiotic–containing nanofibers against a dual-species biofilm and (2) evaluate the ability of dental pulp stem cells (DPSCs) to adhere to and proliferate on dentin upon nanofiber exposure. Methods Seven-day-old dual-species biofilm established on dentin specimens was exposed for 3 days to the following: saline (control), antibiotic-free nanofibers (control), and triple antibiotic–containing nanofibers or a saturated triple antibiotic paste (TAP) solution (50 mg/mL in phosphate buffer solution). Bacterial viability was assessed using the LIVE/DEAD assay (Molecular Probes, Inc, Eugene, OR) and confocal laser scanning microscopy. For cyto-compatibility studies, dentin specimens after nanofiber or TAP (1 g/mL in phosphate buffer solution) exposure were evaluated for cell adhesion and spreading by actin-phalloidin staining. DPSC proliferation was assessed on days 1, 3, and 7. Statistics were performed, and significance was set at the 5% level. Results Confocal laser scanning microscopy showed significant bacterial death upon antibiotic-containing nanofiber exposure, differing significantly (P < .05) from antibiotic-free fibers and the control (saline). DPSCs showed enhanced adhesion/spreading on dentin specimens treated with antibiotic-containing nanofibers when compared with its TAP counterparts. The DPSC proliferation rate was similar on days 1 and 3 in antibiotic-free nanofibers, triple antibiotic–containing nanofibers, and TAP-treated dentin. Proliferation was higher (9-fold) on dentin treated with antibiotic-containing nanofibers on day 7 compared with TAP. Conclusions Triple antibiotic–containing polymer nanofibers led to significant bacterial death, whereas they did not affect DPSC attachment and proliferation on dentin.