Browsing by Author "Matyas, John"
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- ItemOpen AccessAn Analysis of Enthesis-Bone Microstructure: Implications for Paleontological Soft Tissue Reconstructions.(2021-08) Whitebone, Stephanie Amber; Anderson, Jason; Theodor, Jessica; Matyas, JohnIn the absence of direct preservation, evaluating a fossil organism’s soft tissue anatomy can be a daunting task. Studies that aim to evaluate fossil soft tissues must often rely on clear soft tissue bony correlates, such as bony eminences or concavities in the bone surface. These eminences and concavities are formed at the site of soft tissue attachment to bone, called entheses. However, even in large-bodied, adult organisms, a considerable proportion of soft tissues do not leave these clear indicators. Therefore, the evaluation of bony eminences/concavities is coupled with the use of an extant phylogenetic bracket. However, some fossil taxa are so phylogenetically removed from their extant bracketing taxa that anatomical comparisons are dubious at best. I have shown that scanning electron microscopy and histological staining make it possible to identify areas of soft tissue attachment on the bone surface in the absence of macroscopically visible eminences or concavities. There is also a differentiation between tissue types (muscle, tendon, articular cartilage, and aponeurosis) with collagen fibres incorporated into the bone tissue. At areas of articular cartilages, the surface is relatively smooth but with small, organized hummocky structures. Areas of fleshy muscle attachment are generally planar but with occasional round projections where the collagen fibres have been incorporated into bone tissue. Tendon entheses are areas where long string-like collagen fibres have been incorporated into bone tissue, usually within concave impressions on the bone surface. These areas are generally more organized than other entheses. Lastly, aponeurotic entheses are large areas of thick, high-density, disorganized collagen fibres. All four categories of bone surface microstructure have been observed through broad taxonomic sampling using extant organisms, and the same morphologies are also seen in three-dimensional preserved fossil specimens. These four bone surface microstructures are successfully categorized using image classification programming with novel convolutional neural network architecture. Using polarimetry, I quantify the differences between bone surface microstructures by measuring the orientation of collagen fibres and the homogeneity of collagen fibre density throughout the enthesis bone’s thickness.
- ItemOpen AccessAssessment of the Efficacy of MRI for Detectionof Changes in Bone Morphology in a MouseModel of Bone Injury(Wiley, 2013-07-11) Taha, May A; Manske, Sarah; Kristensen, Erika; Taiani, Jaymi; Krawetz, Roman; Wu, Ying; Ponjevic, Dragana; Matyas, John; Boyd, Steven; Rancourt, Derrick; Dunn, Jeffrey F.Purpose To determine whether magnetic resonance imaging (MRI) could be used to track changes in skeletal morphology during bone healing using high-resolution micro-computed tomography (μCT) as a standard. We used a mouse model of bone injury to compare μCT with MRI. Materials and Methods Surgery was performed to induce a burr hole fracture in the mouse tibia. A selection of biomaterials was immediately implanted into the fractures. First we optimized the imaging sequences by testing different MRI pulse sequences. Then changes in bone morphology over the course of fracture repair were assessed using in vivo MRI and μCT. Histology was performed to validate the imaging outcomes. Results The rapid acquisition with relaxation enhancement (RARE) sequence provided sufficient contrast between bone and the surrounding tissues to clearly reveal the fracture. It allowed detection of the fracture clearly 1 and 14 days postsurgery and revealed soft tissue changes that were not clear on μCT. In MRI and μCT the fracture was seen at day 1 and partial healing was detected at day 14. Conclusion The RARE sequence was the most suitable for MRI bone imaging. It enabled the detection of hard and even soft tissue changes. These findings suggest that MRI could be an effective imaging modality for assessing changes in bone morphology and pathobiology.
- ItemOpen AccessEnhanced Electrogastrography Using Transcutaneous Intraluminal Impedance Measurements (TIIM)(2016) Poscente, Michael Dennis; Mintchev, Martin; Yadid-Pecht, Orly; Bartley, Norman; Matyas, John; Murari, Kartikeya; Andrews, ChristopherGastric motility and gastric emptying rates have been implicated in the symptoms of functional dyspepsia and gastroparesis. The current gold standard to assess gastric emptying is scintigraphy, which is limited by standardization and radiation concerns. This highlights the need for a novel method of assessing gastric motility. Transcutaneous Intraluminal Impedance Measurement (TIIM) is a novel method of assessing gastric motility. By measuring the dynamics of a known signal emitted from a battery-powered gastric retentive oscillator within the stomach, gastric motility can be quantified. In an eight-dog sham comparison study, TIIM was compared to force transducers implanted on the stomach. Two assessment metrics demonstrated statistically significant Pearson correlation coefficients between active TIIM pills and the force transducers (p<0.01, p<0.05), but not when TIIM pills were replaced by sham deactivated pills (p>0.1, p>0.1). A novel portable TIIM receiver was also proposed and tested in the lab to facilitate future ambulatory studies.
- ItemOpen AccessGeneration of Tissue-Engineered Cartilage Constructs in Stirred Suspension Bioreactors(2016) Allen, Leah Marie; Sen, Arindom; Hart, David; Matyas, John; Ungrin, Mark; Schmidt, Tannin; Ramirez-Serrano, AlejandroTraumatic injuries to articulating joints, such as the knee and hip, can result in the formation of defects within the articular cartilage contained therein. These defects do not heal spontaneously and can initiate a degenerative process, eventually resulting in osteoarthritis (OA). Current cartilage repair options are limited and do not result in the regeneration of durable cartilage. Mesenchymal stem cells (MSCs) isolated from the synovial fluid within joints have an inherent ability to differentiate towards a chondrogenic lineage. Tissue engineered cartilage constructs (TECs) formed from MSCs have been shown to contribute to cartilage repair when implanted into a defect site, thereby providing a potential approach to prevent the onset or the progression of OA. TECs have traditionally been formed in the wells of static culture plates and serum-containing medium. Unfortunately, TECs made in this manner can exhibit variable characteristics which are likely exacerbated by the use of animal-sourced serum in the medium. Therefore, a need still exists to better optimize the generation of uniform TECs to enhance the clinical translatability of this otherwise promising technology. This work investigated the aggregation and culture of human MSCs within suspension bioreactors and serum-free culture conditions for eventual use in filling articular cartilage defects. It also investigated the impact of low-oxygen tension and chondrogenic medium to enhance the MSC differentiation into a chondrogenic phenotype. Expanding on a body of knowledge, this work demonstrated the ability of suspension bioreactors to create a population of aggregates using serum-free culture conditions and non-osteoarthritic human SF-MSCs. Additionally, it demonstrated that the application of low-oxygen tension and chondrogenic growth factors to the suspension bioreactor system is simple. The culture of MSC aggregates in suspension bioreactors under low-oxygen tension resulted in up-regulated gene expression for aggrecan, significantly more collagen/DNA production, and less necrosis on the inside of the aggregates as compared to ambient oxygen tension. The application of chondrogenic medium to the aggregates in the suspension bioreactors resulted in enhanced collagen type-II gene expression and deposition as compared to the static TECs. Although, the overall amount of ECM quantified and staining for glycosaminoglycans was more prominent in the static TECs.
- ItemOpen AccessIntervertebral Disc Inflammation: The Effect Of Il-1ra Deficiency On Development, Aging And Injury Of The Murine Caudal Intervertebral Disc(2018-01) Swamy, Ganesh; Matyas, John; Salo, Paul; Jirik, Frank; Duncan, NeilIntervertebral disc inflammation: The effect of IL-1Ra deficiency on development, aging and injury of the murine caudal intervertebral disc Inflammation is a coordinated, balanced and redundant cellular response to threats to homeostasis, and leads to tissue repair and regeneration. In the musculoskeletal system, inflammation is central in such reparative processes as fracture healing and wound repair. Inflammation in the intervertebral disc has been broadly implicated in mainly catabolic or degenerative cellular and matrix processes, and cited as the driver of intervertebral disc (IVD) degeneration. We pursued the hypothesis that increased IL-1 activity accelerates the natural history of IVD degeneration. In this study, we assembled a multi-modal platform to evaluate murine caudal IVD structure (through structured histomorphometry and stereology) and function (through dynamic and elastic biomechanics). We also examined gene expression of whole murine IVD (through QPCR analysis) to evaluate IVD response patterns and localized inflammatory gene expression (through immunohistochemistry). Through detailed study of structure, function and molecular response in vivo, the role of inflammation was contrasted between natural aging in genetically normal mice, mice deficient in IL-1Ra, and in both genotypes in the well-characterized pinprick model. In the first set of investigations, we characterized normal aging of the C57BL/6J caudal IVD, from age 3 to 36 months. In the second set of investigations, we characterized the natural history of IVD changes in the IL-1Ra (-/-) mouse on a C57BL/6J background. In our last set of investigations, we examined the effect of injury via the caudal pinprick injury. When synthesized, there is a predictable structure and functional change in aging caudal IVDs, which is accelerated in IL-1Ra (-/-) mice. Inflammatory gene expression is co-regulated with antagonist genes in the IVD. Despite marked changes in gene expression profiles in injury, wild-type and IL-1Ra (-/-) mice demonstrate similar structural and functional changes. The studies described herein have served to increase the importance of IL-1 related inflammation as a driver of degenerative changes in the IVD, and set the stage for further mechanistic analyses.
- ItemOpen AccessMagnetic Resonance Imaging for Tracking of Cells and Agents Targeted to Bone Fracture(2015-04-29) Taha, May; Dunn, Jeff; Matyas, JohnRegenerative medicine is likely to play a major role in the treatment of musculoskeletal diseases. Stem cell therapies could be used to restore damaged or diseased tissues by contributing to the healing process. Additionally, bone targeted nanoparticles could be of great use in this field, as they can be used to deliver therapies or to image an injury site. In order to evaluate and monitor new regenerative therapies in preclinical models over time, a non-invasive in vivo imaging tool is needed. Use of such an imaging method will enable testing new cell therapies in bone. Magnetic resonance imaging (MRI) holds considerable promise for this purpose. Considering that it is a non-invasive and non ionizing method makes it well-suited for repeated measurements studies. Initially, we optimized an MRI protocol for visualization of bone injuries, and then we compared the optimized MRI protocol with µCT as the gold standard for bone imaging. We found that MRI offers several advantages over µCT, including that it visualized soft tissue, edema, therapeutic biomaterials, and is especially useful when ionizing radiation is to be avoided. Subsequently, we used MRI to assess materials used in this study such as bone targeted nanoparticles, contrast agents and stem cell scaffolds. After establishing the MRI protocol, we labelled-differentiated ESCs, and then transplanted them in vivo for MR tracking. The results showed that MRI detected the labelled cells in vivo that under some conditions the MRI could detect migration of the differentiated ESC’s to remote site of injury. The findings were validated by histology and immunohistochemistry. To our knowledge, this is the first study to track cells in bone fracture using MRI. Based on the results of this research, future studies can use the developed cell tracking model for testing the effectiveness of novel cell therapies that promote bone repair.
- ItemOpen AccessSerum-Free Culture of Human Mesenchymal Stem Cell Aggregates in Suspension Bioreactors for Tissue Engineering Applications(2019-11-07) Allen, Leah M.; Matyas, John; Ungrin, Mark; Hart, David A.; Sen, ArindomMesenchymal stem cells (MSCs) have the capacity to differentiate towards bone, fat, and cartilage lineages. The most widely used culture and differentiation protocols for MSCs are currently limited by their use of serum-containing media and small-scale static culture vessels. Suspension bioreactors have multiple advantages over static culture vessels (e.g., scalability, control, and mechanical forces). This study sought to compare the formation and culture of 3D aggregates of human synovial fluid MSCs within suspension bioreactors and static microwell plates. It also sought to elucidate the benefits of these techniques in terms of productivity, cell number, and ability to generate aggregates containing extracellular matrix deposition. MSCs in serum-free medium were either (1) inoculated as single cells into suspension bioreactors, (2) aggregated using static microwell plates prior to being inoculated in the bioreactor environment, or (3) aggregated using microwell plates and kept in the static environment. Preformed aggregates that were size-controlled at inoculation had a greater tendency to form large, irregular super aggregates after a few days of suspension culture. The single MSCs inoculated into suspension bioreactors formed a more uniform population of smaller aggregates after a definite culture period of 8 days. Both techniques showed initial deposition of extracellular matrix within the aggregates. When the relationship between aggregate size and ECM deposition was investigated in static culture, midsized aggregates (100-300 cells/aggregate) were found to most consistently maximize sGAG and collagen productivity. Thus, this study presents a 3D tissue culture method, which avoids the clinical drawbacks of serum-containing medium that can easily be scaled for tissue culture applications.
- ItemOpen AccessThe Effects of Resistance Strength Training and Functional Strength Training on Risk Factors for Running Injury(2016) Baltich, Jennifer; Nigg, Benno; Emery, Carolyn; Stefanyshyn, Darren; Edwards, Brent; Hamill, Joseph; Matyas, JohnReduced muscular strength and relatively larger magnitudes of movements and moments at the lower extremity joints during running have been proposed as risk factors for sustaining an injury. Some have suggested that increased movements at the joints are partially due to reduced muscular strength. However, the influence of strength training on running mechanics has yet to be evaluated in a group of novice runners, which have been shown to be particularly prone to injury. Therefore, the purposes of this thesis were to 1) compare changes in strength, running mechanics, and balance and 2) to explore injury risk for novice runners enrolled in a resistance strength training program, a functional movement strength training program or a stretching control program. One hundred and twenty nine novice runners (18-60 years old, less than two years running experience) were randomly assigned to one of three groups: a “resistance” strength training group (n=43), a “functional” strength training group (n=43) or a stretching “control” group (n=43). Participants were asked to complete a home-based training program three to five times a week for the eight week training period. Following this training period, participants were asked to complete their respective training at least twice a week for a sixteen week maintenance period. Changes in strength, running mechanics, and balance pre- to post-training were compared between groups. Running injuries were self-reported and defined as any complaint sustained in relation to running that caused a restriction in running for at least one week. Eighty-six participants completed the follow up assessment (functional=34, resistance=28, control=24). Changes in lower extremity strength were similar between the training groups with all groups demonstrating strength gains at multiple lower extremity joints. Changes in running mechanics were small in magnitude and within the measurement error of the testing protocol. The functional training group demonstrated improved balance using force plate and field based measures of balance. Though exploratory in nature, injury rates were not different between the three training groups. The results of this thesis indicate that running and completing a home-based strength training program did not increase strength or reduce joint movements more than running and stretching for a group of novice runners.
- ItemOpen AccessThe Identification of Bipotent Dermal Stem Cells and The Role of Anti-Inflammatory Macrophages During Hair Follicle Regeneration(2016) Rahmani, Waleed; Biernaskie, Jeff; Matyas, John; Dobrinski, Ina; Yates, Robin; Cobb, John; Ito, Mayumi; Kurrasch, DeborahThe mechanisms underlying tissue regeneration span a broad spectrum of distinct yet interconnected biological processes that are largely modulated by tissue resident stem cells and the host immune system. In the skin, epithelial stem cells, the adjacent mesenchyme, and resident immune cells play important roles in regulating adult hair follicle (HF) regeneration. Previous work has uncovered distinct hair follicle stem cell (HFSC) populations responsible for maintaining the epithelial compartments of the HF. However, the cellular dynamics within the mesenchymal compartments of the HF (the dermal sheath and dermal papilla) are less understood. Indeed, how these specialized inductive cells are maintained over successive cycles of regeneration and degeneration is an unresolved question. Through in vivo fate mapping of adult HF dermal sheath (DS) cells, I found that a subset of DS cells is retained following each hair cycle, exhibit self-renewal, and repopulate the DS and dermal papilla (DP) with new cells. In vivo clonal analysis of DS cells revealed that individual DS cells exhibited bipotency and self-renewal, thus providing evidence for the existence of a stem cell within the adult HF mesenchyme. Ablating bipotent HF dermal stem cells (hfDSCs) retarded hair regrowth and altered hair type specification. This work has valuable implications toward restoration of hair growth after injury, disease and aging. Immune cells integral players during wound healing and tissue regeneration. The HF affords a unique model to gain insight into the cellular and molecular mechanisms by which cutaneous macrophages influence stem cell function during tissue regeneration. I took advantage of wound-induced hair growth (WIHG), a phenomenon by which skin injury triggers regeneration of surrounding HFs, to explore the relationship between wound macrophages, HFSCs, and tissue regeneration. Using a variety of transgenic approaches, I show that 8-10 days after injury, CD11b+ CX3CR1hi CCR2+ Ly6Clo macrophages increase the perifollicular concentrations of TGF1, activate epithelial stem/progenitors within the secondary hair germ and ultimately stimulate HF regeneration. Furthermore, WIHG was abolished in mice deficient for CX3CR1 but not CCR2. These findings identify a novel mechanism by which anti-inflammatory macrophages stimulate HFSCs to trigger HF regeneration in response to skin injury.
- ItemOpen AccessThe Terry Rapid Razor Section Method for Intraoperative Diagnosis: Revival for Contemporary Application(2016) Duchesne, Stéphan R.; Wright, James Jr; Naugler, Christopher; Matyas, John; Brundler, Marie-Anne; Benediktsson, Hallgrímur; Wright, James Jr; Naugler, Christopher; Armstrong, GlenDuring and after World War I, Unna’s polychrome methylene blue, a supravital stain critical to the Mayo Clinic’s frozen section technique, became unavailable. Benjamin Taylor Terry (1876-1955) developed a replacement stain, and an intraoperative diagnostic method (rapid razor sections) that was arguably better, faster, and inexpensive compared with frozen sections. However, Terry’s contributions to the history of surgical pathology are largely unknown. But his efforts helped solidify the role of hospital-based pathology practice in North America. He played critical roles in stain development, popularization of intraoperative diagnostic techniques, and the institutionalization of hospital-based pathology. After thoroughly studying Terry’s life and the evolution of his methodology, his method was revived and adapted to a contemporary environment. Using a new sectioning device and modifications to his methodology, tissue sections were produced, stained, examined microscopically, and critiqued. Further research in perfecting diagnostic-worthy sections could provide a benefit to pathology laboratories in resource-limited countries.