Research

Focus Areas:

Welcoming a diverse group of students, the Priddy Lab ensures students can follow their interests when working on projects. We collaborate with experts in the field of biomedical engineering across academia, industry, and clinical practice. In particular, we regularly work with veterinarians from MSU’s College of Veterinary Medicine. Our research focuses on two broad topics, bone healing and infection mitigation.


Bone Healing

Treatment of large bone defects resulting from traumatic injury or tumor resection represents a significant challenge for orthopedic surgeons. Despite advances in therapeutics (e.g., recombinant protein technologies), the materials used for fixation of bone (to stabilize it and promote healing) are often much stronger than bone, which can lead to stress shielding, poor osseointegration, implant loosening/failure, pain, and revision surgeries for removal of the implant.


Polymers

We are using 3D printing to create customized, load-bearing thermoplastic polymer scaffolds, and surface functionalization techniques to enhance bioceramic coatings of the polymers (e.g., polylactic acid, poly(lactic-co-glycolic acid), and poly(B-caprolactone)). Utilizing these technologies, our goal is to engineer patient-specific biomaterials that mimic both the mechanical and biological properties of native bone tissue.

Alkali treatment facilitates functional nano-hydroxyapatite coating of 3D printed polylactic acid scaffolds. Weitong Chen, Luke Nichols, Frank Brinkley, Kelson Bohna, Wenmeng Tian, Matthew W. Priddy, Lauren B. Priddy. Materials Science & Engineering: C (In press).

Dopamine-assisted nano-hydroxyapatite coating on 3D printed poly(lactic-co-glycolic acid) scaffolds. Weitong Chen, Luke Tucker, Landon Teer, Lauren B. Priddy. Biomedical Sciences Instrumentation 56(1), 1-9, 2020.

Effects of alkali treatment time on nano-hydroxyapatite coating of 3D printed poly(lactic-co-glycolic acid) scaffolds. Weitong Chen, Luke Tucker, Jaden Bennett, Luke Nichols, Lauren B. Priddy. Bioceramics 31, 31, 21-29, 2019.



Metals

We are also exploring biodegradable magnesium and its alloys for use in temporary implants. Material characterization techniques such as surface profilometry and surface chemistry analysis are used to assess the ability of surface coatings and alloying to modulate the degradation of the alloys, to enhance material performance in the physiological environment. Future work will include cytotoxicity, biocompatibility, and novel alloy development of magnesium-based materials.



Polymer-based composite printing

The development of 3D printed polymer-based composites (blended with bioceramics or metals) for bone tissue engineering and fracture fixation will enable customized scaffold structures (e.g., controllable porosity, pore shape and size) with enhanced mechanical and biological properties (e.g., osteoconductivity/inductivity). The pneumatic, syringe-based, and thermoplastic printing approaches allow flexibility in material selections and combinations, and the capability of incorporating bioactive materials (e.g., growth factors and living cells) into the polymer substrate for tissue regenerative applications. We have established a systematic concept-verification system from material preparation, fabrication, post-printing modifications, to structural/surface characterizations and mechanical and in vitro testing. Our goal is to provide personalized (made to order) implants, avoid revision surgeries, minimize pain, and maximize the improvement of quality of life.



Biomechanical characterization of fracture fixation and healing

Fractures, notably those resulting from high-energy traumas such as vehicular impacts or falls, are often complex/oblique in nature, are challenging to treat, and can result in implant loosening or failure, especially in non-compliant veterinary patients. With collaborators at MSU’s College of Veterinary Medicine, we design and construct customized mechanical testing devices to simulate anatomical loading geometries and evaluate the efficacy of: (i) novel fixation devices for stabilizing bone fractures, and (ii) therapeutics for bone healing in large animal models.

Ex vivo biomechanical comparison of 2.7 mm string-of-pearl plate versus screw/wire/Polymethylmethacrylate composite fixation and 2.7 mm veterinary acetabular plate for repair of simulated canine acetabular fractures . Jonathan A. Blakely, James R. Butler, Lauren B. Priddy, Emily M. McCabe, Javier N. Avendaño, Steve H. Elder, Robert Wills. BMC Veterinary Research, 15(287), 1-9, 2019

Effects of short- and long-term administration of nonsteroidal anti-inflammatory drugs on osteotomy healing in dogs. Hayley M. Gallaher, James R. Butler, Robert W. Wills, Lauren B. Priddy, Steven H. Elder, Sarah M. Heller, Erin Brinkman, Wes Baumgartner. Veterinary Surgery, 1-12, 2019.

A biomechanical comparison of conventional dynamic compression plates and string-of-pearls™ locking plates using cantilever bending in a canine ilial fracture model. Allison R. Kenzig, James R. Butler, Lauren B. Priddy, Kristen R. Lacy, Steven H. Elder. BMC Veterinary Research, 13, 222, 2017.



Infection Mitigation

Difficulties in treating osteomyelitis, or the infection of bone, have been exacerbated by the rise of antibiotic resistant bacterial strains, particularly Staphylococcus aureus, and chronic infection remains a huge clinical burden. Development and characterization of novel antimicrobial therapeutics designed for targeted, prolonged delivery in clinically relevant scenarios will provide a new capacity to combat these most challenging, recalcitrant infections. Using a biofilm forming, green fluorescent protein (GFP) modified strain of S. aureus, we established an implant-based rat model of composite femoral and soft tissue chronic infection as a testbed for evaluating transformative biomaterial technologies. Fluorescent and radiographic images allow for longitudinal monitoring of infection in vivo.

Innovations in osteomyelitis research: A review of animal models. Kylie M. Roux, Leah H. Cobb, Marc A. Seitz, Lauren B. Priddy. Animal Models and Experimental Medicine (Accepted).

Therapeutics and delivery vehicles for local treatment of osteomyelitis Leah H. Cobb, Emily M. McCabe, Lauren B. Priddy. Journal of Orthopaedic Research,1-13, 2020.


CRISPR-Cas9 bacteriophage

As populations of antibiotic resistant bacteria continue to spread and new strains are isolated, engineering alternative therapeutics such as bacteriophage will be essential to augment the dwindling list of effective, available antibiotics. To this end, we are studying the antimicrobial efficacy of a novel CRISPR-Cas9 modified bacteriophage delivered in alginate hydrogel against S. aureus infection.

CRISPR-Cas9 modified bacteriophage for treatment of Staphylococcus aureus induced osteomyelitis and soft tissue infection Leah H. Cobb, JooYoun Park, Elizabeth A. Swanson, Mary Catherine Beard, Emily M. McCabe, Anna S. Rourke, Keun Seok Seo, Alicia K. Olivier, Lauren B. Priddy. PLoS ONE, 14(11):e0220421, 2019.



Collagen-elastin-like-polypeptide hydrogels

In collaboration with Dr. Amol Janorkar at the University of Mississippi Medical Center, composite collagen-elastin-like polypeptide (ELP) hydrogels are being explored for doxycycline and bone morphogenetic protein-2 (BMP-2) delivery to treat osteomyelitis and promote bone healing. The collagen-ELP hydrogels can be further combined with bioceramics, and the ratio of components tailored to enhance mechanical and drug release properties of the gels.



Chitosan-PCL composite biomaterials

The objective of this work is to evaluate the efficacy of a new chitosan-poly(caprolactone) (PCL) biomaterial to deliver the antibiotic fosfomycin to the site of osteomyelitis, for treatment of bone infection. To create hybrid chitosan-PCL biomaterials, 3D printed PCL scaffolds serve as a barrier to contain the chitosan hydrogel and to introduce more control over presentation and release of antibiotic. By harnessing the antimicrobial properties of chitosan for prolonged antimicrobial activity, the dose of antibiotic may be lowered, minimizing the risk of both host toxicity and pathogen antimicrobial resistance.



Poloxamer 407

This study examined the effects of autoclave sterilization on the behavior of Poloxamer 407 hydrogel when used as a drug delivery vehicle. This hydrogel was previously utilized in the osteomyelitis studies, and it was found to be effective for in vitro delivery of antibiotics even after autoclaving.

Autoclaving of Poloxamer 407 hydrogel and its use as a drug delivery vehicle. Mary Catherine Beard, Leah H. Cobb, Christine S. Grant, Anandavalli Varadarajan, Taylor Henry, Elizabeth A. Swanson, Santanu Kundu, Lauren B. Priddy. Journal of Biomedical Materials Research: Part B - Applied Biomaterials, 109B, 338-347, 2021.

Novel use of Poloxamer 407 – Antibiotic compounds to treat antimicrobial-resistant soft tissue infections in dogs Elizabeth A. Swanson, Leah Horstemeyer, Bethany Foust, Lauren B. Priddy. Biomedical Sciences Instrumentation,55(1), 1-13, 2019.