Absorbable anti-inflammatory tendon fixation technology applied to patients for the first time

Northwestern biomedical engineer Guillermo A. Ameer has achieved a rare major achievement. A medical product based on a new biomaterial pioneered by his laboratory will be widely used in musculoskeletal surgery, directly benefiting patients.

The biomaterial technology called CITREGEN™ developed by the start-up company Acuitive Technologies, Inc. is embodied in Stryker Corporation’s CITRELOCK™, which will be the first of its kind at the annual meeting of the American Orthopaedic Association to be held this week in Charlotte The unveiled innovative device, the NC CITRELOCK™ Tendon Fixation Device System, is used to connect soft tissue grafts to bones in reconstructive surgery, and thanks to Ameer's biomaterials, it provides surgeons with a differentiated design​​​ 

CITREGEN™ has unique chemical and mechanical properties for orthopedic surgical applications, helping to heal transplanted tissues. It contains organic molecules including citrate, phosphate and calcium, which are essential for healthy bone growth. CITREGEN™ is the first thermoset biodegradable synthetic polymer used in implantable medical devices.

 The implantable device CITRELOCK™ was approved by the U.S. Food and Drug Administration (FDA) last year. The CITRELOCK™ device has compressive strength comparable to cortical bone and maintains structural integrity during the healing phase, while allowing the implant to be reshaped by the host tissue over time.

As the founding director of Northwestern University’s Center for Advanced Regenerative Engineering (CARE) and the director of the regenerative engineering training program recently funded by the National Institutes of Health, Ameer’s mission is to use engineering and labor training to implement the practice of regenerative medicine to improve surgical outcomes and enable Patients benefit. But generally, medical technology derived from academic research takes several years to be adopted by companies, and it takes more than ten years to obtain approval or approval from regulatory agencies such as the FDA.

The Daniel Hale Williams Professor of Biomedical Engineering at Northwestern University’s McCormick School of Engineering and Ameer, Professor of Surgery at Northwestern University’s Feinberg School of Medicine, reviewed his and his team’s nearly 20 years of experience in developing innovative biomaterial technologies.

"When I started my laboratory at Northwestern University a few years ago, one of my main goals was to use engineering to have a positive impact on patient care. This goal has always been the guiding principle of my research. I tried to collaborate with surgeons to Fully understand medical problems, patient needs, limitations and propose solutions," Ameer said.

“We developed a citrate-based polymer about 18 years ago and initially studied its application in vascular and orthopedic tissue engineering. For the latter, we created a composite material of polymer and ceramic mixture, which is CITREGEN 2006. Other researchers from all over the world expanded our work, the most famous of which may be my former postdoctoral intern Yang Jian, now Dorothy Fowler of Regeneration Engineering at Pennsylvania State University and Chairman J. Lloyd Hack.

"Ten years later, through cooperation with the industry, we were able to initiate the conversion process and use our polymer technology for innovative bioresorbable orthopedic equipment. Although it will take 20 years for our technology to enter the market, we are lucky to be able to Achieve this milestone in my academic career."  

"The reason for promoting the development of citrate polymers and composite materials is the need to use elastic materials like rubber, which are easy to customize, can support cell function, and can be safely dissolved in the body while being replaced by normal tissues-because there was no Such a material. We worked with excellent students and post-doctoral teams to invent a material with various requirements in mind from the beginning. These include the body’s degradation mechanism, the ability to easily synthesize using safe components, and the potential for Application of modularity to control the properties of materials. Over the years, we and others have demonstrated that citrate-based polymers can be designed to help regenerate blood vessels, skin, heart, cartilage, bone, bladder, and muscle tissue."

"Surgeons and patients need better bioabsorbable devices that can promote tissue regeneration or at least not interfere with tissue regeneration. Because of the problems with implants made of traditional biodegradable polymers and regulatory agencies reviewing new It’s not easy to launch new devices made of new bioabsorbable polymers on the market. It’s a long process, but it’s worth bringing to the market through mature medical device companies. New solution."

"Although we are in a leading position in this biomaterial technology and have been working for nearly 20 years, the important credit is still due to visionary individuals from the industry, especially Acuitive Technologies and Stryker, who recognize the benefits of our technology. Potential and invest resources in its development and verification. Acuitive spent six years developing CITREGEN™ into useful products. The cooperation and partnerships established by CARE are essential for replicating the success of CITREGEN™ in other health applications and for the future development of other types of products. The transformation of regenerative engineering technology into clinical practice is very important."

Ameer's work has been recognized recently with the 2021 Clemson Award for Contributions to the Literature and numerous other honors, including being elected Fellow of the Biomedical Engineering Society, American Institute of Chemical Engineers, Materials Research Society, American Institute of Medical and Biological Engineering, American The Association for the Advancement of Science and the National Institute of Inventors.

Ameer is also a member of the Simpson Querrey Institute, the Institute of Life Process Chemistry, and the International Institute of Nanotechnology.

Ameer and Northwestern have economic interests in VesselTek BioMedical—the start-up that the technology was originally licensed for. Ameer also serves on the scientific advisory board of Acuitive Technologies.

CITREGEN™ is the third Northwestern Technology medical technology company that Stryker has brought to market. After Stryker acquired his medical device company Mako in 2013, the robotic arm invented by Michael Peshkin in 1997 entered the orthopedics market. The cement mixer of Richard Wixson, a former professor at the Northwest Dental School, was also purchased and developed by Stryker.

"Citregen is an exciting addition to Stryker's existing biomaterial product portfolio, which will be expanded for other trauma and extremity indications in the future," said Michael Rankin, vice president of marketing and medical education for Stryker's foot and ankle business.

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