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RESEARCH PROJECTS, INFRASTRUCTURE AND COLLABORATIONS

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OVERALL RESEARCH ACTIVITY

      The research activity in Dr. Uludag's lab concentrates on conceptualization and development of novel biomaterials and drug delivery systems. This activity is focused on manipulation of molecular and cellular elements in physiological systems so as to enhance and optimize tissue regeneration in desired biosystems. The primary emphasis of the current research is in Bone Regeneration, where new formation of bone tissue is pursued by using a variety of protein Growth Factors. The traditional engineering principles, rational design and optimization, are applied to obtain bone regeneration locally (at a specific site) or systemically (throughout the body). All projects are experimentally oriented and students are encouraged to evaluate the developed biomaterials/drug delivery systems on the bench and then in animals. Specific research expertise required (and gained) includes organic chemistry, polymer science, drug-delivery, biochemistry, cell biology, pharmacokinetics-pharmacodynamics relationships and bone physiology.

Bone Regeneration Project

      Several protein Growth Factors (such as Fibroblast Growth Factors and Bone Morphogenetic Proteins) have been identified that have significant potential to stimulate bone formation. The Growth Factors were shown to act as: (1) Mitogens (i.e., induce cell proliferation), (2) Morphogens (i.e., induce cell differentiation), (3) Chemotactic agents (i.e., attract cells to a specific site), and (4) Metabolic regulators (i.e., stimulate/inhibit cellular activity). However, these proteins have not been effectively used in bone regeneration because of the drug delivery challenges (i.e., challenges in delivering the protein to the site of action for an appropriate period of time). We are exploring new ways to deliver the growth factos to bone. Once targeted to the site of activity, the growth factors are expected to stimulate bone formation at a low does and with minimal activity at extraskeletal sites. Ultimately, we are interested in developing clinically useful therapeutic agents for both local and systemic regeneration of mineralized tissue.

Design of Novel Biomaterials and Drug Delivery Systems

      The ability to utilize protein Growth Factors for bone regeneration relies on our ability to build new technologies and approaches to introduce the naturally occurring molecules into physiological systems. This requires synthesis and characterization of a unique set of tools; it requires (i) the synthesis of new biomaterials and molecular entities and (ii) the assembly of the synthesized entities with the biologically active molecules. The following sub-projects are intended to yield the tools for this line of research:

Design of Protein-Reactive Biomaterials:    Protein-reactive polymers can be used for chemical modification of therapeutic proteins to obtain polymer-protein conjugates with desired biological (due to protein component) and pharmacokinetics (due to polymer component) properties. Unlike small reagents, polymeric macromolecules exhibit much slower reaction kinetics and undergo conjugation reaction with multivalent linkages. We are exploring the reactivity of macromolecules with proteins in order to obtain well-characterized polymer-protein conjugates. This project focus is on (1) designing architecturally-controlled polymers with protein reactive moieties and (2) understanding the factors contributing to the overall reactivity. This information will ultimately lead to novel therapeutic agents (i.e., conjugates) with superior properties to the conventional proteins.

Biomaterials for Cell-Specific Interactions:    Synthetic biomaterials that interact with cell surface receptors are required for modulating cellular responses for a desired outcome. Towards this end, we are designing biomaterials that bind to cell surface integrin receptors. This is achieved by incorporating short peptide sequences (e.g., -RGD) into synthetic polymers. The project focus is on understanding the relationship between the way peptide residues are incorporated into a biomaterial and the obtained cell response. In addition, we are exploring other cell surface receptors (such as cadherins and selecting) that will be beneficial in tissue engineering applications.

Engineering Ligands for Bone Targeting:    Proteins with a high affinity to bone can act as a novel class of therapeutic agents for treatment of osteoporosis, a disease characterized by a systemic bone loss. Proteins with a high bone affinity are expected to be targeted to bone after intravenous injection. We are developing several methodologies to impart a bone affinity to a desired therapeutic protein. The project involves designing ligands that have a high affinity to bone. Bench-scale and animal studies are being utilized to determine the ability of the designed proteins to be targeted to bone.

Designing Polymers for DNA Delivery:    Delivering genes of the growth factors, in contrast to delivering the proteins themselves, has the potential to induce a more lasting bone regeneration activity at a desired site. Towards this end, novel biomaterials are being synthesized that bind to DNA strongly. Our intent is to design 'nano'-engineered vesicles, based on architecterally-controlled novel polymers, to facilitate cellular uptake of DNA as well as to ensure its nuclear delivery and expression.

INFRASTRUCTURE AND COLLABORATIONS

      Uludag lab is equipped with facilities to synthesize and characterize small organic molecules and polymeric materials. Local Nuclear Magnetic Resonance (NMR) facilities are available to characterize the structure of the synthesized entities. Routinely used instruments include UV/Visible spectrophotometer (for polymer composition, polymer reactivity, protein assays, etc.), a Waters High Pressure Liquid Chromatographer with a photodiode array detector (for analysis of protein conjugates, molecular weight distribution of polymers), and a Precision Laser Light Scattering Instrument (for analysis of molecular sizes and hydrodynamic radius of polymers and proteins in solution). A synthesis workstation with the capacity to synthesize 24-96 compounds at a time is available to create molecular libraries. Access to local surface plasmon resonance instruments is possible to investigate biomolecular interactions. Cell culture facilities are used to evaluate the biological performance of biomaterials and biological molecules - this is critical before animal experimentation. Tissue processing equipment is available for histological analysis of hard and soft tissues. A radioactive lab is functional for protein labeling to study biodistribution and targeting of therapeutic agents in animals. Animal studies are carried out at the Animal Health Services of the U. of Alberta. When necessary, imaging (Micro CT) and quantitative radiography (DEXA) instruments are utilized at the U. of Calgary and commercial service labs.

      Active research collaborations have been established to complement the research activities in Uludag Lab. The Bone Regeneration Project is being carried out in collaboration with Dr. John Matyas (Department of Cell Biology and Anatomy, U. of Calgary), Dr. Ronald Zernicke (Faculty of Kinesiology, U. of Calgary) and Dr. Shelley Winn (Oregan Health Sciences University, Portland, OR). A collaboration on wound healing and skin regeneration is under way with Dr. Aziz Ghahary (Department of Surgery, U. of Alberta). Biomaterials and tissue engineering infrastructure is continually upgraded in collaboration with local investigators, such as Dr. Mark McDermott (Chemistry), R. Loebenberg (Pharmacy and Pharmaceutical Sciences), Z. Xu (Chemical Engineering) and Drs. R. Rajotte and J. Lakey (Surgical-Medical Reserach Institute), among others. Studies on DNA delivery are carried out in collaboration with Dr. B. Ritchie (Department of Haematology, U. of Alberta) and Dr. H. Icil (Department of Chemistry, Eastern Mediterranean University). Numerous other colleagues are consulted on a regular basis depending on the project needs.