Translational Research

Ultrasound Tissue Characterization

The long-term goal of the Surgical Ultrasound Laboratory at Drexel University College of Medicine is to advance ultrasound technology into the era of cellular and molecular therapeutics. The objective of our current research is to optimize ultrasound technology to identify angiogenesis and apoptosis in tumors ex vivo. We will use this method in vivo in conjunction with established methods to improve accuracy in identification of tumor processes, specifically apoptosis and angiogenesis.

The hypothesis that ultrasound may offer an additional non-invasive diagnostic modality with superior ability to detect lesions is based on our experience with ultrasound technology to characterize carotid plaques. This technique is consistently able to identify tissue with areas that may contain apoptosis or angiogenesis based on size and morphologic criteria. Quantitative ultrasound allows detection of small areas with distinct acoustic characteristics compared to surrounding tissue. Pathologically, these structures can be linked to areas of apoptosis and angiogenesis.

Directed Drug Delivery

Surgical procedures that require anastomosis of small lumen structures such as the common bile duct, ureters, and small blood vessels have not benefited from the reliability and ease of surgical stapling. Use of surgical staples for small structures is limited by small structure size and susceptibility to ill effects from scarring at the tissue joint.

We are working to create a new tissue-joining device that will improve on existing staples, including a smaller version for use with small structures. This new staple will be composed of two parts: a rivet with a hollow lumen for flow of bodily fluids and a ring to secure the approximated tissues. Our current research is focusing on the ring. We are developing a biocompatible ring that will degrade and simultaneously deliver drugs.

Improving the speed, accuracy, and effectiveness of procedures, while lowering the morbidity and mortality rates of surgical interventions, is the overall goal of our laboratory. The objective of this project is to develop a new staple for small lumen structures fabricated from FDA-approved biocompatible, biodegradable polymer that delivers bioactive agents to improve healing. A miniaturized surgical staple that allows delicate structures to be joined safely while maintaining vessel patency will have broad applications in surgery.

More information about this research is available here.

Magnetizable Stents for Drug Delivery

Dr. Zach G. Forbes (Surgery / School of Biomedical Engineering), along with Dr. Gary Friedman (Electrical and Computer Engineering), Dr. Kenneth Barbee (School of Biomedical Engineering), and Dr. Benjamin Yellen (Duke University Department of Mechanical Engineering and Materials), are developing a minimally invasive, targeted drug-delivery system that uses magnetic implants and magnetic nanoparticles to administer repeatable, patient-specific dosages of therapeutic agents to specific sites in the human body. In vivo trials are conducted under the supervision of Dr. Ari Brooks, M.D. (Surgery). Numerous graduate students and residents from the laboratories of Forbes, Friedman, Barbee, Yellen,and Brooks are participating in different aspects of the project. The researchers on the team specialize in the fields of magnetism, fluids, cardiovascular biomechanics, oncology, and surgery

In many cases, currently available drug delivery vehicles (polymer spheres, liposomes, or hydrogels, for instance) do not have a mechanism for localization that allows delivery of high concentrations of drugs with minimally invasive techniques.  This is especially true when repeat dosing is required. Ultrasound-mediated delivery shows promise for regional drug delivery, but lacks the pin point accuracy needed for delivery to vascular walls and isolated tumors. The magnetic drug delivery system proposed herein overcomes many of these difficulties and provides a method for concentrating drugs at selected sites in the body with minimal stress on the patient, with much higher dosages than could be accomplished via systemic drug administration, and without the fear of toxicity.  The first objective of this project is the prevention of coronary restenosis by adapting this system for use in coronary stents, but if successful, the technology can be expanded to numerous applications ranging from cancer therapy to stem cell delivery. In addition, the incorporation of magnetism into the delivery of the various carriers mentioned above may increase their efficacy and expedite their clinical implementation.

Our central hypothesis is that when implanted in vivo, an intra-vascular stent plated with small magnetic features or composed of a weakly magnetic alloy can attract large numbers of injected superparamagnetic particles under the application of a modest external magnetic field.  This procedure is minimally-invasive and allows repeat dosing.  Furthermore, the therapeutic agent and/or the delivery vehicle can be varied. Concurrent ex vivo and in vivo studies have examined a method for targeted drug delivery by applying high magnetic field gradients within the body to an injected superparamagnetic colloidal fluid carrying a drug, with the aid of modest uniform magnetic field.  The design is ideally suited for endovascular implants, such as coronary stents, or other implants with primary functions independent of local drug delivery.

We encourage interested post-doctoral candidates, residents, and faculty to contact us to share input, inquire about opportunities for collaboration, as well opportunities to join our team.