Poly(ethylene glycol) Immunogenicity

Poly(ethylene glycol) (PEG) based hydrogels are a key component of several FDA-approved medical devices and are among the most popular materials being investigated for regenerative engineering. Although PEG is often viewed as a biologically inert material, studies have shown that a significant percentage of the population has circulating antibodies against PEG, and concerns over PEG immunogenicity are growing. 

We are conducting pioneering studies on the impact of anti-PEG immune reactions on the host response to PEG hydrogels and the efficacy of PEG hydrogel-based regenerative engineering therapies. Using a mouse model, we recently found that high anti-PEG titers significantly impacted bone defect regeneration when PEG-based hydrogels were used to deliver an osteoinductive growth factor. Studies to better understand how the immune response to PEG hydrogels is altered and the effects of PEG hydrogel properties are ongoing. This work is currently supported by the National Institute of General Medical Sciences through 1R01GM147821.

Regenerative Engineering

The inability of the human body to regenerate after an injury is at the crux of many of the most significant problems in medicine. We are working to solve this problem by developing biomaterial scaffolds that can guide tissue formation and healing. Our work in this area includes developing new methods for synthesis and fabrication, conducting fundamental studies on cell-material interactions, and performing in vivo studies to evaluate tissue repair and regeneration.  We are particularly interested in granular hydrogels, which are made from hydrogel microparticles and can be engineered to have inherently microporous structures that enhance cell growth and tissue formation compared to conventional hydrogels. 

In collaboration with Dr. Jennifer Dulin and Dr. Jeff Twiss, we are currently developing injectable hydrogel biomaterials for spinal cord regeneration. This work is supported by a grant from the Craig H. Nielsen Foundation. We are also developing injectable hydrogels to facilitate the regeneration of bone defects.

Biomaterials for Medical Devices

We are also applying our expertise in biomaterial synthesis and fabrication to medical device development. In collaboration with Dr. Duncan Maitland, we are developing a biopsy tract sealant device that consists of a hydrogel/shape memory polymer foam composite. This work is supported by the National Cancer Institute through 5R01CA254964. In collaboration with Dr. Mike McShane, we are developing biosensor implants that consist of hydrogel matrices encapsulating biosensor microparticles.

Chemistry of Materials

Chemistry is an integral part of our research. We routinely employ click chemistry-based methods for biomaterial synthesis and functionalization, and we have a longstanding interest in tetrazine click chemistry. Recently, we discovered that the tetrazine-norbornene click reaction can drastically alter hydrogel properties due to strong secondary interactions between the reaction products. Currently, we are working to better understand this phenomenon and exploit it in biomaterial development.