(A-17) Injectable Nanofiber Materials for Alveolar Bone Regeneration

Introduction::
Alveolar bone is a critical tissue for tooth retention. Increasing alveolar bone mass in patients who lose this tissue as a result of periodontal disease or trauma is crucial for successful dental implant therapy (e.g., loss of bone around a tooth extraction site prior to implant placement).^1,2 Currently, bone grafts (e.g., iliac or mandibular bone) and artificial bone grafts are commonly used for repairing alveolar bone defects. However, most of these therapies necessitate extensive surgical procedures, which show risks of many complications, particularly in aged patients. Therefore, the development of new alveolar bone regeneration techniques that do not require large flap surgical procedures is urgently needed.




Materials and Methods:: PCL/gelatin (1:1) nanofiber mats were produced by electrospinning.
^1-4

The nanofiber mat was segmented by Cryostat cutting, freeze-dried, and kept at 4
^o

C for further use. For the fabrication of NMs, the Cryostat-cut segmented fibers were typically dispersed in water at a concentration of 20 mg/mL and homogenized by a probe homogenizer. Then, the well-homogenized nanofiber-dispersed solution was used for the fabrication of various NMs by co-axial electrospraying techniques.

Results, Conclusions, and Discussions::
We demonstrated a simple and versatile approach for engineering nanofiber microspheres with controlled size, predesigned structure, and desired composition by co-axial electrospraying of air in the core and a short nanofiber solution in the shell, respectively (Figure 1).⁴ Varying parameters, such as airflow rates and applied voltages, enables a tunability that is yet to be reported in engineering nanofiber microspheres. We also demonstrated that nanofiber microspheres serving as cell carriers can enhance expansion and differentiation, suggesting the potential use for stem cell therapies. Moreover, we demonstrated the ability to fabricate porous nanofiber microspheres from a broad range of materials with different functionalities, including magneto-responsive, functional peptide-conjugated, ECM composition-mimicking, and inorganic/organic hybrid nanofiber microspheres.^4,5The in vitro and in vivo studies showed that the open porous architecture of the nanofiber microspheres provided an ideal matrix for cellular infiltration and integration with host tissue.⁴


The biomimetic and injectable nanofiber microspheres with sequential delivery of QK and BMP-2 peptides mimicking bone healing and/or incorporation of bone marrow mesenchymal stem cells (BMSCs) could be used to promote alveolar bone regeneration.




Acknowledgements (Optional): :
This work was partially supported by startup funds from University of Nebraska Medical Center (UNMC) and NIHR01 DE031272.




References (Optional): :
1) Boda SK et al. Acta Biomater. 2019, 85, 282-293; 2) Boda SK et al. ACS Biomater. Sci. Eng. 2020, 6, 2368; 3) Boda SK et al. ACS Appl. Mater. Interfaces 2018, 10, 25069; 4) John JJ et al. Small 2020, 16, 1907393; 5) John JJ et al. Nanomedicine: NBM2019, 22, 102081.