Digital Commons Network^™

Cold Atmospheric Pressure Plasma-Antibiotic Synergy In Pseudomonas Aeruginosa Biofilms Is Mediated Via Oxidative Stress Response, Jordanne-Amee Maybin, Thomas P. Thompson, Padrig B. Flynn, Timofey Skvortsov, Noreen J. Hickok, Theresa A. Freeman, Brendan F. Gilmore

Department of Orthopaedic Surgery Faculty Papers

Cold atmospheric-pressure plasma (CAP) has emerged as a potential alternative or adjuvant to conventional antibiotics for the treatment of bacterial infections, including those caused by antibiotic-resistant pathogens. The potential of sub-lethal CAP exposures to synergise conventional antimicrobials for the eradication of Pseudomonas aeruginosa biofilms is investigated in this study. The efficacy of antimicrobials following or in the absence of sub-lethal CAP pre-treatment in P. aeruginosa biofilms was assessed. CAP pre-treatment resulted in an increase in both planktonic and biofilm antimicrobial sensitivity for all three strains tested (PAO1, PA14, and PA10548), with both minimum inhibitory concentrations (MICs) and minimum biofilm eradication …

Approximating Scaffold Printability Utilizing Computational Methods, Ashkan Sedigh, Pejman Ghelich, Jacob Quint, Evelyn C Mollocana-Lara, Mohamadmahdi Samandari, Ali Tamayol, Ryan E. Tomlinson

Department of Orthopaedic Surgery Faculty Papers

Bioprinting facilitates the generation of complex, three-dimensional (3D), cell-based constructs for various applications. Although multiple bioprinting technologies have been developed, extrusion-based systems have become the dominant technology due to the diversity of materials (bioinks) that can be utilized, either individually or in combination. However, each bioink has unique material properties and extrusion characteristics that affect bioprinting utility, accuracy, and precision. Here, we have extended our previous work to achieve high precision (i.e. repeatability) and printability across samples by optimizing bioink-specific printing parameters. Specifically, we hypothesized that a fuzzy inference system (FIS) could be used as a computational method to address …

The Cgas-Sting Pathway Affects Vertebral Bone But Does Not Promote Intervertebral Disc Cell Senescence Or Degeneration, Olivia K. Ottone, C. James Kim, John A. Collins, Makarand V. Risbud

Department of Orthopaedic Surgery Faculty Papers

The DNA-sensing cGAS-STING pathway promotes the senescence-associated secretory phenotype (SASP) and mediates type-I interferon inflammatory responses to foreign viral and bacterial DNA as well as self-DNA. Studies of the intervertebral disc in humans and mice demonstrate associations between aging, increased cell senescence, and disc degeneration. Herein we assessed the role of STING in SASP promotion in STING gain- (N153S) and loss-of-function mouse models. N153S mice evidenced elevated circulating levels of proinflammatory markers including IL-1β, IL-6, and TNF-α, showed elevated monocyte and macrophage abundance in the vertebral marrow, and exhibited a mild trabecular and cortical bone phenotype in caudal vertebrae. Interestingly, …

Abcc6 Null Mice-A Model For Mineralization Disorder Pxe Shows Vertebral Osteopenia Without Enhanced Intervertebral Disc Calcification With Aging, Paige K Boneski, Vedavathi Madhu, Ryan Tomlinson, Irving Shapiro, Koen Van De Wetering, Makarand V Risbud

Department of Orthopaedic Surgery Faculty Papers

Chronic low back pain is a highly prevalent health condition intricately linked to intervertebral disc degeneration. One of the prominent features of disc degeneration that is commonly observed with aging is dystrophic calcification. ATP-binding cassette sub-family C member 6 (ABCC6), a presumed ATP efflux transporter, is a key regulator of systemic levels of the mineralization inhibitor pyrophosphate (PPi). Mutations in ABCC6 result in pseudoxanthoma elasticum (PXE), a progressive human metabolic disorder characterized by mineralization of the skin and elastic tissues. The implications of ABCC6 loss-of-function on pathological mineralization of structures in the spine, however, are unknown. Using the Abcc6 -/- …

Enhancing Precision In Bioprinting Utilizing Fuzzy Systems, Ashkan Sedigh, Dayna Dipiero, Kristy M. Shine, Ryan E. Tomlinson

Department of Orthopaedic Surgery Faculty Papers

Bioprinting facilitates the generation of complex, three-dimensional (3D), cell-based constructs for a variety of applications. Although multiple bioprinting technologies have been developed, extrusion-based systems have become the dominant technology due to the diversity of substrate materials (i.e. bioinks) that can be accommodated, either individually or in combination. Each bioink has unique material properties and extrusion characteristics that limit bioprinting precision, particularly when generating identically shaped constructs from different bioinks. Here, we aimed to achieve high precision (i.e. repeatability) across samples by generating bioink-specific printing parameters using a systematic approach. We hypothesized that a Fuzzy system could be used as a …

Leveraging Advancements In Tissue Engineering For Bioprinting Dental Tissues, Devin Grace Morrison, Ryan E. Tomlinson

Department of Orthopaedic Surgery Faculty Papers

3D bioprinting allows biocompatible materials and cells to be deposited in precise locations in three-dimensional space, enabling researchers to surpass the limitations of traditional 2D cell culture and to create innovative therapies. 3D bioprinting is one of the newest tools developed in the field of tissue engineering, which has traditionally utilized a paradigm revolving around scaffolds, cells, and signals. In this review, we discuss how new developments in each of these three research areas relates to bioprinting dental tissues – specifically teeth, periodontal ligament, and alveolar bone. Important considerations include how scaffold materials and geometry affect regeneration of dental tissues, …

The Trka Agonist Gambogic Amide Augments Skeletal Adaptation To Mechanical Loading., Gabriella Fioravanti, Phuong Q. Hua, Ryan E. Tomlinson

Department of Orthopaedic Surgery Faculty Papers

The periosteal and endosteal surfaces of mature bone are densely innervated by sensory nerves expressing TrkA, the high-affinity receptor for nerve growth factor (NGF). In previous work, we demonstrated that administration of exogenous NGF significantly increased load-induced bone formation through the activation of Wnt signaling. However, the translational potential of NGF is limited by the induction of substantial mechanical and thermal hyperalgesia in mice and humans. Here, we tested the effect of gambogic amide (GA), a recently identified robust small molecule agonist for TrkA, on hyperalgesia and load-induced bone formation. Behavioral analysis was used to assess pain up to one …

Bioactivating A Bone Substitute Accelerates Graft Incorporation In A Murine Model Of Vertical Ridge Augmentation, Jinlong Chen, Xue Yuan, Zhijun Li, Daniel J Bahat, Jill A Helms

Department of Orthopaedic Surgery Faculty Papers

OBJECTIVE: Compared to autologous bone grafts, allogeneic bone grafts integrate slowly, which can adversely affect clinical outcomes. Here, our goal was to understand the molecular mechanisms underlying graft incorporation, and then test clinically feasible methods to accelerate this process.

METHODS: Wild-type and transgenic Wnt "reporter" mice were used in a vertical ridge augmentation procedure. The surgery consisted of tunneling procedure to elevate the maxillary edentulous ridge periosteum, followed by the insertion of bone graft. Micro-computed tomographic imaging, and molecular/cellular analyses were used to follow the bone graft over time. Sclerostin null mice, and mice carrying an activated form of β-catenin …

The Role Of Nerves In Skeletal Development, Adaptation, And Aging., Ryan E Tomlinson, Blaine A Christiansen, Adrienne A Giannone, Damian C Genetos

Department of Orthopaedic Surgery Faculty Papers

The skeleton is well-innervated, but only recently have the functions of this complex network in bone started to become known. Although our knowledge of skeletal sensory and sympathetic innervation is incomplete, including the specific locations and subtypes of nerves in bone, we are now able to reconcile early studies utilizing denervation models with recent work dissecting the molecular signaling between bone and nerve. In total, sensory innervation functions in bone much as it does elsewhere in the body-to sense and respond to stimuli, including mechanical loading. Similarly, sympathetic nerves regulate autonomic functions related to bone, including homeostatic remodeling and vascular …

A Surgeon's Handedness In Direct Anterior Approach-Hip Replacement., Xiangpeng Kong, Minzhi Yang, Alvin Ong, Renwen Guo, Jiying Chen, Yan Wang, Wei Chai

Department of Orthopaedic Surgery Faculty Papers

BACKGROUND: The impact of handedness on clinical outcomes was easily overlooked in hip replacement. This study aimed to find whether the component positioning and hip function were affected by the handedness in total hip arthroplasty (THA) through direct anterior approach (DAA).

METHODS: Total 102 patients who underwent bilateral DAA-THAs simultaneously between May 2016 and November 2018 in our institute were reviewed. All surgeries were operated by one right-handed surgeon. Their demographic, cup positioning, stem alignment, femoral stem fit, Harris hip score (HHS), intraoperative and postoperative complications were used to evaluate the role of handedness in DAA.

RESULTS: The inclination of …

Fracture Repair Requires Trka Signaling By Skeletal Sensory Nerves., Zhu Li, Carolyn A Meyers, Leslie Chang, Seungyong Lee, Zhi Li, Ryan Tomlinson, Ahmet Hoke, Thomas L Clemens, Aaron W James

Department of Orthopaedic Surgery Faculty Papers

Bone is richly innervated by nerve growth factor-responsive (NGF-responsive) tropomyosin receptor kinase A-expressing (TrKa-expressing) sensory nerve fibers, which are required for osteochondral progenitor expansion during mammalian skeletal development. Aside from pain sensation, little is known regarding the role of sensory innervation in bone repair. Here, we characterized the reinnervation of tissue following experimental ulnar stress fracture and assessed the impact of loss of TrkA signaling in this process. Sequential histological data obtained in reporter mice subjected to fracture demonstrated a marked upregulation of NGF expression in periosteal stromal progenitors and fracture-associated macrophages. Sprouting and arborization of CGRP+TrkA+ sensory nerve fibers …

Distal Interphalangeal Joint Arthrodesis Complicated By Postoperative Infection: A Rare Presentation Of Disseminated Herpes Simplex Virus., Meredith N. Osterman, Michael P. Gaspar

Department of Orthopaedic Surgery Faculty Papers

Postoperative infection after elective arthrodesis of the interphalangeal joint is an uncommon complication often necessitating urgent debridement. We present the rare case of a female patient with a history of oral herpetic lesions, who underwent elective arthrodesis of the middle and index fingers for treatment of erosive osteoarthritis and subsequently developed a postoperative herpetic infection at the surgical site.

Chemical Modification Of Extracellular Matrix By Cold Atmospheric Plasma-Generated Reactive Species Affects Chondrogenesis And Bone Formation., Peter Eisenhauer, Natalie Chernets, You Song, Danil Dobrynin, Nancy Pleshko, Marla J Steinbeck, Theresa A. Freeman

Department of Orthopaedic Surgery Faculty Papers

The goal of this study was to investigate whether cold plasma generated by dielectric barrier discharge (DBD) modifies extracellular matrices (ECM) to influence chondrogenesis and endochondral ossification. Replacement of cartilage by bone during endochondral ossification is essential in fetal skeletal development, bone growth and fracture healing. Regulation of this process by the ECM occurs through matrix remodelling, involving a variety of cell attachment molecules and growth factors, which influence cell morphology and protein expression. The commercially available ECM, Matrigel, was treated with microsecond or nanosecond pulsed (μsp or nsp, respectively) DBD frequencies conditions at the equivalent frequencies (1 kHz) or …

Loss Of Hif-1Α In The Notochord Results In Cell Death And Complete Disappearance Of The Nucleus Pulposus., Christophe Merceron, Laura Mangiavini, Alexander Robling, Tremika Leshan Wilson, Amato J Giaccia, Irving Shapiro, Ernestina Schipani, Makarand V Risbud

Department of Orthopaedic Surgery Faculty Papers

The intervertebral disc (IVD) is one of the largest avascular organs in vertebrates. The nucleus pulposus (NP), a highly hydrated and proteoglycan-enriched tissue, forms the inner portion of the IVD. The NP is surrounded by a multi-lamellar fibrocartilaginous structure, the annulus fibrosus (AF). This structure is covered superior and inferior side by cartilaginous endplates (CEP). The NP is a unique tissue within the IVD as it results from the differentiation of notochordal cells, whereas, AF and CEP derive from the sclerotome. The hypoxia inducible factor-1α (HIF-1α) is expressed in NP cells but its function in NP development and homeostasis is …

Concave Pit-Containing Scaffold Surfaces Improve Stem Cell-Derived Osteoblast Performance And Lead To Significant Bone Tissue Formation., Antonio Graziano, Riccardo D'Aquino, Maria Gabriella Cusella-De Angelis, Gregorio Laino, Adriano Piattelli, Maurizio Pacifici, Alfredo De Rosa, Gianpaolo Papaccio

Department of Orthopaedic Surgery Faculty Papers

BACKGROUND: Scaffold surface features are thought to be important regulators of stem cell performance and endurance in tissue engineering applications, but details about these fundamental aspects of stem cell biology remain largely unclear.

METHODOLOGY AND FINDINGS: In the present study, smooth clinical-grade lactide-coglyolic acid 85:15 (PLGA) scaffolds were carved as membranes and treated with NMP (N-metil-pyrrolidone) to create controlled subtractive pits or microcavities. Scanning electron and confocal microscopy revealed that the NMP-treated membranes contained: (i) large microcavities of 80-120 microm in diameter and 40-100 microm in depth, which we termed primary; and (ii) smaller microcavities of 10-20 microm in diameter …