Tissue Engineering Scaffold Fabrication Laboratory

Tissue Engineering Scaffold Fabrication Laboratory

About the Tissue Engineering Scaffold Fabrication Lab

The focus of our lab is the fabrication and evaluation of tissue engineering scaffolds capable of replicating both the form and function of the native extracellular matrix (ECM). Through the creation of idealized tissue engineering structures, we hope to harness the body’s own reparative potential and accelerate regeneration. We are primarily interested in utilization of the electrospinning process to create nanofibrous polymeric structures that can be applied to a wide range of applications. Of principal interest to our laboratory is the fabrication of scaffolds capable of promoting wound healing and the filling of large tissue defects, as well as orthopedic applications such as bone and ligament repair. Our lab is equipped for a number of scaffold fabrication techniques, scaffold mechanical evaluation, protein analysis, and the determination of cell-scaffold interactions.

Projects

  1. Design and fabrication of dermal regeneration templates to stimulate scarless healing in chronic wounds.
    tissue-engineeringPressure ulcer at admission (Top), 5th (Middle), and 11th treatments (Bottom) with PRP therapy.

    Patients suffering from spinal cord injury (SCI) are at lifelong risk of developing pressure ulcers. These ulcers can occur in any setting, the patient’s home, hospital, or care facility, and are a cause of great distress for both patients and caregivers alike. These wounds are typically non-healing, resulting in a downward spiral of chronic inflammation, which can be a source of morbidity and even mortality in immobile or mobility-limited populations.Promoting accelerated healing of pressure ulcers, through the application of an off-the-shelf dermal regeneration template (DRT) would provide improvement to patient quality of life and reduce the economic impact that chronic wounds have on the health care system. Similarly, a DRT capable of reducing scar formation, which can pull skin tight across joints and bony protuberances and increase the risk of ulcer reopening during common practices such as transferring or weight shifting, would hold great potential for alleviating suffering associated with SCI ulcer recurrence and re-hospitalization.

    • The sustained release of platelet-rich plasma derived biomolecules to modify the local cellular response.

      Platelet-rich plasma (PRP) has been gaining popularity in recent years as a cost effective practice capable of stimulating healing in a number of different clinical applications. As the clinical role of PRP has been growing so too has its prevalence in the fields of tissue engineering and regenerative medicine, particularly in the field of extracellular matrix (ECM) analogue scaffold fabrication.  As polymeric scaffold fabrication techniques strive to create structures that ever more closely replicate the native ECM’s form and function, the need for increased scaffold bioactivity becomes more pronounced.  PRP, which has been shown to contain over 300 bioactive molecules, has the potential to deliver a combination of growth factors and cytokines capable of stimulating cellular activity through enhanced chemotaxis, proliferation, and ECM production.  The ability to incorporate such a potent bioactive milieu into a polymeric tissue engineering scaffold, which lacks intrinsic cell signaling molecules, may help to promote scaffold integration with native tissues and increase the overall patency of polymeric ECM analogue structures.

    • The use of air-impedance electrospinning to create structures conducive to cellular infiltration.

      tissue-engineeringInside surface of AIE scaffold (Left) compared to inside surface of traditional electrospun scaffold (Right). Note the large pores of decreased fiber density in the AIE structure (Magnification =100X).

      In recent years, electrospinning has proven to be an effective technique for scaffold fabrication. However, the typically fine pore structure associated with the process limits the ability to cellularize the entire scaffold, resulting in mainly cell seeding of the surface. A recently published technique known as air-impedance electrospinning (AIE) has the potential to overcome these limitations by increasing scaffold porosity while maintaining structural integrity.The inclusion of this innovative AIE method for the fabrication of the DRT has the ability to create structures with significantly enhanced porosity; thereby creating structures that are more conducive to cellular infiltration and remodeling.

      This method of electrospinning stands apart from traditional electrospinning techniques in that it affords direct control over scaffold porosity through controlled interruption in fiber deposition, whereas traditional electrospinning is reliant upon the linear relationship between fiber size and pore size, or post-processing techniques to control porosity.

    • Investigation of the potential use of Manuka honey in the treatment of chronic wounds.

      Honey had been used medicinally for centuries, due to its inherent wound healing capacity. However, the introduction of penicillin significantly reduced its role. Recently, with the emergence of antibiotic-resistant bacteria and a better scientific understanding of how honey influences healing, honey (specifically active Leptospermumhoney from New Zealand, known as Manuka) has once again become an acceptable product in the treatment of wounds.The major benefit of Manuka honey lies in its potent antibacterial properties. Honey has a high osmolarity and a high sugar content, the combination of which has been shown to inhibit microbial growth.

      tissue-engineeringcGraph of the mean % area healed for each of the test medias at 6, 12, 18, and 30 hr post-wounding in an in vitro wound healing assay with human dermal fibroblasts. The combination of PRP and Manuka honey had significantly higher rates of healing. 

      Manuka honey is also known to have a relatively low pH (3.5-4.5), which, in addition to inhibiting microbial growth, will stimulate the bactericidal actions of macrophages, and in chronic wounds reduce protease activity, increase fibroblast activity, and increase oxygenation.

      Hydrogen peroxide is slowly released from honey placed on a wound through the interaction of wound exudates with the honey’s inherent glucose oxidase. This hydrogen peroxide is in sufficient concentration to be antibacterial, yet dilute enough to be non-toxic while promoting fibroblast proliferation and angiogenesis. Manuka honey also possesses non-peroxide antibacterial activity in what is called the Unique Manuka Factor (UMF) due to the presence of methylglyoxal. Manuka honey can be used in combination with PRP to stimulate cellular response in a chronic wound.
       

  2. Design and fabrication of tissue engineering scaffolds for orthopedic applications.

    Composition (i.e., biomaterials of synthetic or natural origin) and architecture (i.e. fiber orientation and diameter, pore size, etc.) of a tissue engineered scaffold results in cell-environment interactions that determine the structure’s fate. The ultimate goal is to enable the body to heal itself by introducing a tissue engineered scaffold that the body recognizes as “self”, and in turn, uses to regenerate “neo-native” functional tissues. The environmental conditions of a successful tissue engineered scaffold must be appropriate such that signals can be exchanged between cells and between cells and the environment with the goal of restoring tissue function. One such critical signal, especially in a load bearing orthopedic tissue, are the mechanical stresses that a tissue engineered scaffold will undergo. Scaffolds in orthopedic applications must be able to withstand the often cyclic loading conditions applied to them by the body, while bio-resorbing at a rate consistent with natural tissue ingrowth to prevent loss of mechanical integrity.

    tissue-engineeringDiagram of the air-gap electrospinning process (Left) and a scanning electron micrograph of a wound ligament analogue scaffold (Right).
    • The use of air-gap electrospinning for fabricating ligament analogue structures.

      The process of electrospinning has proven highly beneficial for use in a number of tissue engineering applications due to its ease of use, flexibility, and tailorable properties. There have been many publications on the creation of aligned fibrous structures created through various forms of electrospinning, most involving the use of a metal target rotating at high speeds. This work focuses on the use of a variation known as air-gap electrospinning, which does not use a metal collecting target but rather a pair of grounded electrodes equidistant from the charged polymer solution to create highly aligned 3D structures.

    • The fabrication of alginate-based scaffolds for intervertebral disk regeneration.
      tissue-engineeringScanning electron micrograph of a dehydrated alginate microsphere.

      Intervertebral discs (IVD) degenerate faster than any other connective tissue in the body in what is known as degenerative disc disease (DDD). The cause of DDD has been linked to aging, with degradation of the collagen extracellular matrix (ECM) in the inner nucleus pulposus (NP) and outer annulus fibrosus (AF) being of paramount concern. Additionally, the accumulation of pro-inflammatory cytokines within the tissue and the gradual senescence of inherent cell populations, resulting in a lack of collagen matrix production, make IVD repair nearly impossible. This work focuses on the use of alginate, a polysaccharide derived from brown algae. Alginates are biocompatible and resorb in the body without harmful degradation by-products.  Alginate biopolymers can serve as delivery systems for a number of biologic entities (i.e. cells, growth factors, cytokines, etc.) without causing undesirable side effects, and can have tailorable mechanical properties and rates of degradation.

Additional Resources