CENTER FOR ADVANCED
REGENERATIVE ENGINEERING

Stryker recently announced the launch of Citrefix a suture anchor system for foot and ankle surgical procedures. The new system uses a citrate-based biomaterial referred to as Citregen, a bioresorbable material designed to mimic the chemistry and structure of native bone. Citrate-based biomaterials were originally developed by Guillermo Ameer’s team at Northwestern University for tissue engineering and regenerative medicine applications. Ameer was awarded the Society for Biomaterials Technology Innovation and Development Award in 2022 for his work on these materials. Polydiolcitrates are the first biodegradable thermoset polymers used for implantable medical devices cleared by the U.S.A. Food and Drug Administration for use in surgeries.  

Citrefix is a disposable suture anchor system that features a resorbable biomimetic anchor body. Citregen enables controlled resorption without chronic inflammation. Citregen's unique chemical and mechanical properties are designed to help grafted tissue heal and healthy bone grow when used in orthopaedic surgical applications. After the launch of Citrelock in 2021, Citrefix is the second product in Stryker’s portfolio using the material, with additional products expected in 2023.

To view the full press release, please click HERE. 

Samantha Huddleston, recent PhD graduate in Biomedical Engineering (June 2022, advisor: Professor Guillermo Ameer), performs research involving augmenting a tough citrate-based polymer to promote bone regeneration at the site of implantation/application.  Her paper “Azo polymerization of citrate-based biomaterial-ceramic composites at physiological temperatures” is featured on the cover of the most recent issue of Nano Select and discusses her work in the development and material characterization of a thermoresponsive, degradable bone cement.

Samantha Huddleston is currently a Postdoctoral Fellow at the University of Missouri, working with the BioMEL (Biomodulatory Materials Engineering Lab) under Dr. Bret Ulery.

Title: Azo polymerization of citrate-based biomaterial-ceramic composites at physiological temperatures
Authors: Samantha E. Huddleston, Chongwen Duan, Guillermo A. Ameer
Publication: Nano Select, Volume 3, Issue 10, October 2022, pages 1421-1435

Northwestern Engineering’s Guillermo A. Ameer has been named the 2022 Bioactive Materials Lifetime Achievement Award winner by the Bioactive Materials academic journal.

Established in 2021, the annual Bioactive Materials Lifetime Achievement Award recognizes excellence in research and development in the field of bioactive materials. The award is presented to a person judged to have demonstrated excellence and leadership in bioactive materials, including basic science and translation to practice. 

Ameer, Daniel Hale Williams Professor of Biomedical Engineering at the McCormick School of Engineering and professor of surgery at the Feinberg School of Medicine, is a leader in regenerative engineering, biomaterials, additive manufacturing for biomedical devices, controlled drug delivery, and bio/nanotechnology for therapeutics and diagnostics. His laboratory has pioneered the development of tissue regeneration applications of citrate-based biomaterials, the core technology behind the innovative bioresorbable orthopedic tissue fixation devices CITREFIXTM, CITRESPLINETM, and CITRELOCKTM, which were recently cleared by the FDA for clinical use and marketed worldwide by Stryker Corporation.

Northwestern Engineering's Guillermo A. Ameer was one of three University faculty elected to the National Academy of Medicine (NAM).   Election to the Academy is considered one of the highest honors in the fields of health and medicine, and Professor Guillermo Ameer’s laboratory is widely recognized for pioneering regenerative biomaterials based on a novel class of biodegradable polymers containing citrate, and using them to regenerate a variety of tissues and organs.

Ameer is the Daniel Hale Williams Professor of Biomedical Engineering in the McCormick School of Engineering and a professor of surgery in Northwestern’s Feinberg School of Medicine, and also the founding director of Northwestern’s Center for Advanced Regenerative Engineering. He is director of the recently established Regenerative Engineering Training Program at the McCormick School of Engineering, supported by the National Institutes of Health.

Read the full article in Engineering News.

Northwestern Engineering’s Guillermo Ameer was one of three Northwestern faculty named on the Researchers to Know 2022 list by the Illinois Science and Technology Coalition (ISTC).

Ameer, Daniel Hale Williams Professor of Biomedical Engineering at the McCormick School of Engineering, professor of surgery at the Feinberg School of Medicine, and director of the Center for Advanced Regenerative Engineering, was cited under the medical technology category. Ameer is a leader in regenerative engineering, biomaterials, additive manufacturing for biomedical devices, controlled drug delivery, and bio/nanotechnology for therapeutics and diagnostics. 

The ISTC is a member-driven non-profit​, nonpartisan organization that cultivates technology-based economic development throughout Illinois.​ Its annual Researchers to Know list provides a look at some of the researchers that are driving innovation in the state — from those advancing new treatments in medicine, to those revolutionizing sustainability practices and shaping new technologies in the 21st century.

Read the full article in Engineering News

September 24, 2021

The novel biomaterial Citregen™, developed in the Center for Advanced Regenerative Engineering, is being adopted into a new orthopaedic device being distributed by Stryker.  Stryker is one of the world’s leading medical technology companies, and their Trauma & Extremities division has launched its Citrelock™ Tendon Fixation Device System.  Citregen’s unique chemical and mechanical properties make this system an innovative offering in a number of ways.  For example, it provides a controlled and homogeneous resorption process that prevents bulk degradation and chronic inflammation, and maintains structural integrity during the healing phase, while the implant is replaced by host tissue.

Read Stryker’s press release, find more information about Stryker’s product release here.

The development and commercialization of a novel biomaterial is a rare accomplishment.  Read an article in Northwestern Now by Lila Reynolds that features the development of CITREGEN™ in Dr. Ameer's labs.

Watch Stryker's video to learn more about Citrelock technology:

Medical devices that use biomaterial technology developed at CARE receive FDA clearance

March 4, 2021

Three devices using the core material technology CITREGEN™, pioneered by Dr. Guillermo Ameer and his lab, have received U.S. Food and Drug Administration (FDA) approval.  These devices were designed by Acuitive Technologies.

The CITRESPLINE/CITRELOCK™ system (pictured right) is intended to firmly engage tendons and ligaments within a bone tunnel while preserving the integrity of the soft tissue during insertion of the device. These products are intended to be used during orthopedic surgeries for fixation of ligament or tendon tissue repairs of the knee, shoulder, elbow, wrist, hand, ankle, and foot.  Acuitive Technologies, Inc. intends to commercialize the CITRESPLINE and CITRELOCK System with an orthopedic distribution partner to compete in the Sports Medicine market. 

Read the full press release by Acuitive Technologies, Inc. here.

Learn more about CITREGEN™ technology.

February 15, 2021

The CITREFIX™ Knotless Suture Anchor System (pictured right) is intended to assist the attachment of tissue to bone during orthopedic surgeries such as fixation of ligaments or tendon graft tissue repairs of the shoulder, elbow, wrist, hand, knee, ankle, and foot extremities.  Read more about the product and announcement here.

October 2020

The Center for Advanced Regenerative Engineering, led by its director  Guillermo Ameer, has pioneered an innovative orthopedic medical device fabricated from a novel biomaterial, and has received clearance from the U.S. Food and Drug Administration (FDA) for use in surgeries to attach soft tissue grafts to bone.

The biomaterial is the first thermoset biodegradable synthetic polymer ever approved for use in an implantable medical device.  Ameer’s biomaterial, called CITREGEN™, helps grafted tissues heal by recreating their intrinsic biochemical and structural support network.  CITREGEN™ is the core material technology in the CITRELOCK™ Interference Screw System (pictured above).  The system is intended for soft tissue attachment or fixing ligaments and tendon graft tissue in joint surgeries. 

“CITREGEN is an unprecedented and innovative bioresorbable biomaterial technology developed to support the body’s normal healing process and promote tissue regeneration,” Ameer said. “When used to fabricate devices for reconstruction of tissues, such as ligaments, blood vessels, bladder and bone, results have been impressive and beyond our expectations.”

Read the full story about the device as covered by Northwestern News.

Housed within the McCormick School of Engineering and Applied Science, the Center for Advanced Regenerative Engineering (CARE) is a targeted initiative led by Prof. Guillermo Ameer that integrates and supports research, technology development, and clinical expertise to improve the outcome of tissue and organ repair and regeneration for adult and pediatric patients. CARE is a partnership that includes Northwestern University's Feinberg School of Medicine, the University of Chicago's Pritzker School of Medicine, the Shirley Ryan AbilityLab, the Ann and Robert H. Lurie Children’s Hospital of Chicago, the International Institute for Nanotechnology, and various companies interested in the implementation of regenerative medicine.