Education & Certifications

  • Master of Science, Stanford University, BIOE-MS (2022)
  • BS, San José State University, Biomedical Engineering (2019)

All Publications

  • Aspirin synergizes with mineral particle-coated macroporous scaffolds for bone regeneration through immunomodulation. Theranostics Su, N., Villicana, C., Zhang, C., Lee, J., Sinha, S., Yang, A., Yang, F. 2023; 13 (13): 4512-4525


    Rationale: Mineral particles have been widely used in bone tissue engineering scaffolds due to their osteoconductive and osteoinductive properties. Despite their benefits, mineral particles can induce undesirable inflammation and subsequent bone resorption. Aspirin (Asp) is an inexpensive and widely used anti-inflammatory drug. The goal of this study is to assess the synergistic effect of Asp and optimized mineral particle coating in macroporous scaffolds to accelerate endogenous bone regeneration and reduce bone resorption in a critical-sized bone defect model. Methods: Four commonly used mineral particles with varying composition (hydroxyapatite v.s. tricalcium phosphate) and size (nano v.s. micro) were used. Mineral particles were coated onto gelatin microribbon (µRB) scaffolds. Macrophages (Mφ) were cultured on gelatin µRB scaffolds containing various particles, and Mφ polarization was assessed using PCR and ELISA. The effect of conditioned medium from Mφ on mesenchymal stem cell (MSC) osteogenesis was also evaluated in vitro. Scaffolds containing optimized mineral particles were then combined with varying dosages of Asp to assess the effect in inducing endogenous bone regeneration using a critical-sized cranial bone defect model. In vivo characterization and in vitro cell studies were performed to elucidate the effect of tuning Asp dosage on Mφ polarization, osteoclast (OC) activity, and MSC osteogenesis. Results: Micro-sized tricalcium phosphate (mTCP) particles were identified as optimal in promoting M2 Mφ polarization and rescuing MSC-based bone formation in the presence of conditioned medium from Mφ. When implanted in vivo, incorporating Asp with mTCP-coated µRB scaffolds significantly accelerated endogenous bone formation in a dose-dependent manner. Impressively, mTCP-coated µRB scaffolds containing 20 µg Asp led to almost complete bone healing of a critical-sized cranial bone defect as early as week 2 with no subsequent bone resorption. Asp enhanced M2 Mφ polarization, decreased OC activity, and promoted MSC osteogenesis in a dosage-dependent manner in vivo. These results were further validated using in vitro cell studies. Conclusions: Here, we demonstrate Asp and mineral particle-coated microribbon scaffold provides a promising therapy for repairing critical-sized cranial bone defects via immunomodulation. The leading formulation supports rapid endogenous bone regeneration without the need for exogenous cells or growth factors, making it attractive for translation. Our results also highlight the importance of optimizing mineral particles and Asp dosage to achieve robust bone healing while avoiding bone resorption by targeting Mφ and OCs.

    View details for DOI 10.7150/thno.85946

    View details for PubMedID 37649612

    View details for PubMedCentralID PMC10465219

  • Stem Cell Membrane-coated Microribbon Scaffolds Induce Regenerative Innate and Adaptive Immune Responses in a Critical-Size Cranial Bone Defect Model. Advanced materials (Deerfield Beach, Fla.) Su, N., Villicana, C., Barati, D., Freeman, P., Luo, Y., Yang, F. 2022: e2208781


    Naturally-derived cell membranes have shown great promise in functionalizing nanoparticles to enhance biointerfacing functions for drug delivery applications. However, its potential for functionalizing macroporous scaffolds to enhance tissue regeneration in vivo remains unexplored. Engineering scaffolds with immunomodulatory functions represents an exciting strategy for tissue regeneration but is largely limited to soft tissues. Critical sized bone defects cannot heal on its own, and the role of adaptive immune cells in scaffold-mediated healing of cranial bone defects remain largely unknown. Here we report mensenchymal stem cell membrane (MSCM)-coated microribbon (muRB) scaffolds for treating critical size cranial bone defects via targeting immunomodulation. Confocal imaging and proteomic analyses were used to confirm successful coating and characterize the compositions of cell membrane coating. We demonstrate MSCM coating promotes Mphi polarization towards regenerative phenotype, induces CD8+ T cell apoptosis, and enhances regulatory T cell differentiation in vitro and in vivo. MSCM primed with pro-inflammatory cytokines enhances regenerative immune response and promotes MSC osteogenesis. When combined with a low dosage of BMP-2, primed MSCM coating further accelerates bone regeneration and suppresses inflammation. These results establish cell membrane-coated microribbon scaffolds as a promising strategy for treating critical size bone defects via immunomodulation. The platform may be broadly used with different cell membranes and scaffolds to enhance regeneration of multiple tissue types. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/adma.202208781

    View details for PubMedID 36560890

  • Immunomodulatory strategies for bone regeneration: A review from the perspective of disease types. Biomaterials Su, N., Villicana, C., Yang, F. 2022; 286: 121604


    Tissue engineering strategies for treating bone loss to date have largely focused on targeting stem cells or vascularization. Immune cells, including macrophages and T cells, can also indirectly enhance bone healing via cytokine secretion to interact with other bone niche cells. Bone niche cues and local immune environment vary depending on anatomical location, size of defects and disease types. As such, it is critical to evaluate the role of the immune system in the context of specific bone niche and different disease types. This review focuses on immunomodulation research for bone applications using biomaterials and cell-based strategies, with a unique perspective from different disease types. We first reviewed applications for prolonging orthopaedic implant lifetime and enhancing fracture healing, two clinical challenges where immunomodulatory strategies were initially developed for orthopedic applications. We then reviewed recent research progress in harnessing immunomodulatory strategies for regenerating critical-sized, long bone or cranial bone defects, and treating osteolytic bone diseases. Remaining gaps in knowledge, future directions and opportunities were also discussed.

    View details for DOI 10.1016/j.biomaterials.2022.121604

    View details for PubMedID 35667249