ABS 097: Tunable and Injectable Microporous Annealed Particles for Improved Peri-Implantitis Healing

Raymond Nova ¹ , Timothy Liu ¹ , Katherine Lim ¹ , Gauri Arora ¹ , Alex Edmonson ¹ , Prisha Bali ¹ , Crystal Chan ¹ , Zachary Ching ¹ , Nathan Choup ¹ , Jenna Dougherty ¹ , James Heeter ¹ , Rubaba Kamal ¹ , Madeline Kuan ¹ , Aarthi Raghavan ¹ , Shardul Singh ¹ , Khanh Tran ¹

¹ Biomedical Engineering Society, Department of Bioengineering, University of California, Los Angeles (UCLA)

Van Wickle (2025) Volume 1, ABS 097

Introduction: With the aging global population and declining oral health, the demand for peri-implantitis treatments—the leading cause of implant failure—is on the rise. Injectable microporous hydrogels offer a promising therapeutic platform due to their biocompatibility and extracellular matrix-mimetic properties, which promote cellular growth and tissue regeneration. Microporous Annealed Particle (MAP) gels represent a novel class of self-assembling hydrogels with tunable porosity, yet their utility in peri-implantitis treatment remains largely unexplored.

To enhance the bioactivity of these gels, we developed an injectable and crosslinkable Gelatin Methacryloyl (GelMA) MAP gel loaded with BMP-2, a growth factor known to promote osteogenesis and cellular proliferation. This system was designed to provide localized and sustained delivery of BMP-2 while supporting tissue remodeling through its microporous structure. Incorporating antibacterial agents such as metal nanoparticles is also being considered to further reduce infection risk at the implant site.

To simulate oral enzymatic degradation, MAP gels were incubated in a 2U/mL type II collagenase solution at 37 C. Degradation was monitored via 20X microscopy over 10 days, and ImageJ analysis showed a steady decrease in average gel radius, following the model 0.314t2 − 3.665t +13.628. ELISA confirmed BMP-2 release correlating with degradation, with higher BMP-2 loading (~38 ng/mL) showing prolonged release compared to lower loading (~13 ng/mL).

Future work includes assessing biocompatibility and osteogenic potential on 3T3 fibroblasts differentiated into osteoblasts. Cell viability will be analyzed via LIVE/DEAD assays, and Sirius Red staining will quantify collagen production. These results will help determine MAP gels' ability to support bone regeneration.

Thus, MAP gels are promising as tunable, injectable scaffolds for targeted peri-implantitis therapy through sustained BMP-2 delivery and controlled degradation.

Methods: GelMA was synthesized by dissolving porcine skin gelatin in DPBS at 50C, followed by dropwise addition of methacrylic anhydride under stirring. After 2 hours, the reaction was stopped with warm DPBS. To form MAP microgels, the GelMA solution, combined with Eosin Y, TEOA, and NVC, was emulsified into mineral oil containing Span 80 at 50C, then crosslinked. BMP-2 was mixed into the prepolymer solution before gelation for sustained delivery. Microgels were washed, centrifuged and stored at 4C for further analysis.
To simulate oral enzymatic degradation, gels were incubated in 2U/mL type II collagenase at 37C. Images were captured daily at 20X magnification over 10 days and analyzed using ImageJ. Future experiments include seeding 3T3 fibroblasts onto gels, assessing viability via LIVE/DEAD assays, and quantifying osteogenic collagen production with Sirius Red staining.

Results: We demonstrated that MAP gel degradation in type II collagenase follows the model r = 0.314t2 − 3.665t +13.628 (r = average radius, t = days). ELISA assays confirmed that BMP-2 release increased with gel degradation and stabilized once full material exposure was achieved.
Higher BMP-2 loading (~38 ng/mL), resulted in a longer period of sustained release compared to lower loading (~13 ng/mL). These results validate MAP gels as a tunable delivery platform for controlled growth factor release.

Discussion: The consistent degradation timeline of the particle supports the potential of MAP gels as controlled delivery vehicles for growth factors. This system could enhance precision in tissue engineering applications, where spatial and temporal regulation of growth factors is critical for cell differentiation and tissue regeneration. These findings are especially relevant for peri-implantitis treatment, where localized bone regeneration is essential. Future work will explore engineering MAP gels responsive to dynamic stimuli and optimizing material properties (e.g. gelatin concentration, microgel uniformity) to further refine growth factor delivery.