Engineering Commons^™

Injectable Gelatin-Silk Fibroin Composite Hydrogels For In Situ Cell Encapsulation, Ryann D. Boudreau

Honors Theses and Capstones

Hydrogels are widely used tools for tissue engineering and regenerative medicine. Characterized as biofunctional, water-based polymer matrices with tunable mechanical properties, hydrogels have promising but limited applications in biomedical engineering, due to poor and static matrix strength. Here we plan to rectify this issue by introducing a new hydrogel made from a composite of gelatin and silk fibroin crosslinked by microbial transglutaminase (mTG) instantly and beta sheet formation gradually, respectively. This interpenetrating network (IPN) shows enhanced mechanical stiffness and strength compared to gelatin hydrogels, and is capable of encapsulating human cells with high viability demonstrated by the encapsulation of human …

Designing Biomimetic Implant Surfaces To Promote Osseointegration Under Osteoporotic Conditions By Revitalizing Mechanisms Coupling Bone Resorption To Formation, Ethan M. Lotz

Theses and Dissertations

In cases of compromised bone remodeling like osteoporosis, insufficient osseointegration occurs and results in implant failure. Implant retention relies on proper secondary fixation, which is developed during bone remodeling. This process is disrupted in metastatic bone diseases like osteoporosis. Osteoporosis is characterized low bone mass and bone strength resulting from either accelerated osteoclast-mediated bone resorption or impaired osteoblast-mediated bone formation. These two processes are not independent phenomena. In fact, osteoporosis can be viewed as a breakdown of the cellular communication connecting bone resorption to bone formation. Because bone remodeling occurs at temporally generated specific anatomical sites and at different times, …

Bisphosphonate Functionalized Gold Nanoparticles For The Study And Treatment Of Osteoporotic Disease, Christopher Conners

USF Tampa Graduate Theses and Dissertations

The use of nanoparticles for disease treatment is an increasingly popular area of research. The potential for multi-functionality allows nanoparticles to be used as transport and delivery vehicles for drugs and as diagnostic aides, among other applications, to address the unmet needs of many disease treatments. One such class of disease is osteoporosis including severe disorders, like Paget’s disease, Osteogenesis Imperfecta and Legg Calve Perthes disease. In this dissertation, we discuss a nanoparticle system consisting of gold nanoparticles surface functionalized with primary amine bisphosphonates, which is a classification of pharmaceuticals that is common in the treatment of osteoporosis. Functionalized nanoparticles …

Phospho1 Deficiency Transiently Modifies Bone Architecture Yet Produces Consistent Modification In Osteocyte Differentiation And Vascular Porosity With Ageing, Behzad Javaheri, Alessandra Carriero, Katherine Ann Staines, Y.-M. Chang, D. A. Houston, Karla J. Oldknow, José Luis Millán, Bassir N. Kazeruni, Phil L. Salmon, Sandra J. Shefelbine

Biomedical Engineering and Sciences Faculty Publications

PHOSPHO1 is one of principal proteins involved in initiating bone matrix mineralisation. Recent studies have found that Phospho1 KO mice ( Phospho1-R74X) display multiple skeletal abnormalities with spontaneous fractures, bowed long bones, osteomalacia and scoliosis. These analyses have however been limited to young mice and it remains unclear whether the role of PHOSPHO1 is conserved in the mature murine skeleton where bone turnover is limited. In this study, we have used ex-vivo computerised tomography to examine the effect of Phospho1 deletion on tibial bone architecture in mice at a range of ages (5, 7, 16 and 34. weeks of age) …

In Vitro Simulation Of Pathological Bone Conditions To Predict Clinical Outcome Of Bone Tissue Engineered Materials, Duong Nguyen

All Dissertations

According to the Centers for Disease Control, the geriatric population of ≥65 years of age will increase to 51.5 million in 2020; 40% of white women and 13% of white men will be at risk for fragility fractures or fractures sustained under normal stress and loading conditions due to bone disease, leading to hospitalization and surgical treatment. Fracture management strategies can be divided into pharmaceutical therapy, surgical intervention, and tissue regeneration for fracture prevention, fracture stabilization, and fracture site regeneration, respectively. However, these strategies fail to accommodate the pathological nature of fragility fractures, leading to unwanted side effects, implant failures, …

Mechanical Properties Of Human Amniotic Fluid Stem Cells Using Nanoindentation, Ashkan Aryaei, Ambalangodage Jayasuriya

Faculty Publications

The aim of this study was to obtain nanomechanical properties of living cells focusing on human amniotic fluid stem (hAFS) cell using nanoindentation techniques. We modified the conventional method of atomic force microscopy (AFM) in aqueous environment for cell imaging and indentation to avoid inherent difficulties. Moreover, we determined the elastic modulus of murine osteoblast (OB6) cells and hAFS cells at the nucleus and cytoskeleton using force–displacement curves and Hertz theory. Since OB6 cell line has been widely used, it was selected to validate and compare the obtained results with the previous research studies. As a result, we were able …

Calcium Phosphate-Based Resorbable Biomaterials For Bone Regeneration, Daniel O. Costa

Electronic Thesis and Dissertation Repository

Bone defects are a prevalent problem in orthopedics and dentistry. Calcium phosphate-based coatings and nanocomposites offer unique solutions towards producing scaffolds with suitable physical, mechanical and biological properties for bone regeneration.

We developed a novel method to synthesize hydroxyapatite (HA) particles with high aspect ratio using sol-gel chemistry and hydrothermal treatment. We obtained tunable pure-phase carbonated-HA in the form of micro/nanorods and nanowires (diameters 25-800 nm). To mimic the structure of bone, HA nanowires were homogenously mixed within poly(ε-caprolactone) (PCL) to produce nanocomposites with improved mechanical properties as determined by uniaxial tensile testing.

Surface chemistry and topography of biomaterials play …

Effects Of Nicotine On Rabbit Bone Marrow Derived Osteoblastic Cells, S. Sylvester, Timothy L. Norman, J. C. France, N. Mukherjee

Engineering and Computer Science Faculty Presentations

No abstract provided.

Image Analysis Of Primary Bone-Derived Cells On Different Polystyrene Surfaces, R. M. Shelton, G. Landini

Cells and Materials

The aim of the present study was to examine whether two different cell populations could be discerned using image analysis of a variety of morphological parameters on bacteriological and tissue culture polystyrene surfaces. Rat periosteal and osteoblast cultures were established on both polystyrene petri dishes and examined using phase contrast microscopy after one and two weeks before capturing digital images which were stored on a personal computer. The digital images were processed to identify the cell margins or perimeter, from which seven different morphological parameters were calculated using a program developed (by GL) for both the cell populations on the …

Gap Junctional Intercellular Communication In Bone, Henry J. Donahue, Monique A. Vander Molen, Clare E. Yellowley, Zhongyong Li

Cells and Materials

Gap junctional intercellular communication has been demonstrated in bone cells and may contribute to the mechanism by which osteoblasts integrate and amplify extracellular signals, both chemical (hormonal) and biophysical (electrical and mechanical). Connexin 43 (Cx43) is the predominant gap junction protein expressed by bone cells. Experiments with osteoblastic cells in which Cx43 expression was diminished by antisense transfection demonstrate that cell-to-cell coupling in osteoblastic ROS 17/2.8 cells is via gap junctions composed of Cx43. Cellular networks of these coupling deficient clones are dramatically less responsive to parathyroid hormone (PTH) suggesting that coupling contributes to hormonal responsiveness. Furthermore, PTH per se …

Analysis Of The Bony Interface With Various Types Of Hydroxyapatite In Vitro, J. D. De Bruijn, J. S. Flach, K. De Groot, C. A. Van Blitterswijk, J. E. Davies

Cells and Materials

Rat bone marrow cells, capable of forming bonelike tissue, were cultured on three types of plasma sprayed hydroxyapatite that differed in degree of crystallinity from 15%, 43% to 69%. The interface between the mineralized extracellular matrix and the hydroxyapatite was studied with scanning and transmission electron microscopy. At the onset of bone formation, calcium and phosphorous-rich afibrillar globules, with a diameter varying from 0.2 to 0.8 μm, were produced and deposited onto the different substrata. These globules subsequently fused to form a homogeneous layer to which collagen fibres became anchored. Individual globules could be distinguished on the non-degrading 69 % …

Ultrastructural, Cytochemical, And Immunocytochemical Studies On Bone And Its Interfaces, M. D. Mckee, A. Nanci

Cells and Materials

Bone cells possess the ability to synthesize, secrete and direct the assembly and maintenance of extracellular matrix to form a functionally rigid and/or weight-bearing mineralized tissue complex, the skeleton. The skeleton not only supports and protects the organs and tissues of the body, but also acts as a mineral ion reservoir for maintaining systemic calcium balance (calcium homeostasis). The remarkable biological precision necessary for the formation, turnover and constant adaptation of bone to external mechanical forces is a dynamic process requiring a coordinated cellular effort relying on a variety of cell-cell and cell-matrix/mineral interactions. Indeed, cell-matrix interfaces found in a …

Influence Of Crystal Structure On The Establishment Of The Bone-Calcium Phosphate Interface In Vitro, J. D. De Bruijn, C. P. A. T. Klein, K. De Groot, C. A. Van Blitterswijk

Cells and Materials

An in vitro rat bone marrow cell system was used to examine the interfacial ultrastructure established between various calcium phosphates and mineralized tissue. The investigated calcium phosphates comprised hydroxyapatite (HA), fluorapatite (FA), tricalcium phosphate (TCP), tetracalcium phosphate (TECP) and magnesium whitlockite (MWL). Both scanning and transmission electron microscopy were used to examine the elaborated interface. The time in which a mineralized extracellular matrix was formed on the various materials differed from 2 weeks on HA, TCP and TECP, to 8 weeks on FA. It was only occasionally observed in some areas on MWL, which might have been due to aluminum …

The Role Of Implant Surface Geometry On Mineralization In Vivo And In Vitro; A Transmission And Scanning Electron Microscopic Study, B. Chehroudi, J. Ratkay, D. M. Brunette

Cells and Materials

The purpose of th.is study was to examine the effect of substratum surface topography on bone formation in vivo and in vitro. Precise control over substratum topography was achieved using micromachining, a technique developed from the fabrication of microelectronic components. In the in vivo studies, titanium-coated epoxy replicas of micromachined surfaces were implanted subcutaneously in the parietal area of rats. After 6 weeks, bone-like tissue was found adjacent to some micromachined surfaces. Detailed observation of this tissue with the transmission electron microscope revealed osteoblast/osteocyte-like cells and a fully or partially mineralized collagenous matrix. Mineralized matrix and collagen bundles were …

Deposition And Resorption Of Calcified Matrix In Vitro By Rat Marrow Cells, J. E. Davies, R. Chernecky, B. Lowenberg, A. Shiga

Cells and Materials

Rat bone marrow derived cells were cultured using a-Minimal Essential Medium supplemented with antibiotics, ascorbic acid and !3-glycerphosphate in the presence of 10-8M dexamethasone, on polystyrene and hydrophilic fluorocarbon substrata for periods of 2 - 4 weeks. During this time, a large yield of bone nodules was achieved and the elaborated tissue was examined by both scanning and transmission electron microscopy. The matrix produced by the cells contacting the underlying substratum was an afibrillar, globular, calcified material which formed a layer approximately 0.5μm thick. The calcium and phosphorus content of this material was confirmed by energy dispersive X-ray dot mapping …

Ultrastructural Study Of Bone Formation On Synthetic Hydroxyapatite In Osteoblast Cultures, J. M. Sautier, J. R. Nefussi, N. Forest

Cells and Materials

Collagenase isolated rat calvaria cells forming a mineralized matrix in vitro were cultured in the presence of synthetic hydroxyapatite. Interactions between bone cells and hydroxyapatite biomaterial were followed by transmission electron microscopy. The appearance of a granular, collagen free, electron-dense layer at the periphery of the material was noted initially. Progressively, an amorphous, granular material formed and extended between the hydroxyapatite aggregates. Osteoblastic cells then synthesized an osteoid matrix which mineralized on the first formed granular collagen free layer, following a classical pattern of calcification . Demineralization of ultrathin sections confirmed the presence of this interface between the material and …