Jayasuriya The goal of this proposal is to develop injectable microparticles based on a natural biopolymer, chitosan, and calcium phosphate, seeded with mesenchymal stem cells in combination with either macrophages or their secretory factors (which have been shown to increase the osteoblast phenotype). The long-term goal is to achieve a new approach for regenerating natural bone tissues, thereby overcoming limitations of current bone grafts. A strength of this research is the incorporation of activated macrophages into the microparticles to act as a source of bioactive factors for osteoblast differentiation and bone regeneration. This approach would allow the cell-based delivery of multiple factors, and potentially avoid complicated pharmaceutical formulations. It also has the potential for injection of the microparticles that has key advantages over large prefabricated biomaterial scaffolds. Multiple exciting training, mentoring, and outreach activities are planned.
Intellectual Merit: This project led to producing hybrid polymer microparticles to apply as bone graft substitute materials. The produced microparticles were biocompatible, biodegradable and osteoconductive. This project provides a great impact in applications related to bone regeneration. The hybrid microparticles were prepared by the emulsification method using inorganic components such as calcium phosphate, calcium carbonate and an organic component such as chitosan. We studied in vitro biodegradation of microparticles; they started to degrade in phosphate buffered saline within 25-30 weeks. Therefore, these microparticles will give necessary support at the defect site until newly formed tissue growth is complete. These microparticles attached to different types of cells including murine mesenchymal stem cells harvested from murine bone marrow, osteoblasts (bone forming cells), and macrophages. We also studied mesenchymal stem cell attachment, proliferation, and gene expression on hybrid microparticles as a function of time. Macrophages secreted important growth factors for bone regeneration, including bone morphogenetic protein-2 and transforming growth factor. Expression of bone morphogenetic protein-2 and transforming growth factor in macrophages was stimulated after lipopolysaccharide activation. We also studied secretion of bone-specific growth factors from lipopolysaccharide-activated macrophages. Based on the intellectual property of this grant, one patent application is currently pending. Based on the outcomes of this grant, the principal investigator received the National Science Foundation I-Corps Award. Broader Impact: One Ph.D. dissertation in Biomedical Engineering was completed with full support from this grant and one doctoral student in Mechanical Engineering was partially supported by this grant. Four bioengineering undergraduates including two females, were trained for research activities. Several graduate students in biomedical engineering and biomedical sciences programs were supported for their lab rotation supplies through this grant. Several local high school students and three teachers were trained for research activities with this grant in summers of 2008-2012. Eleven peer-reviewed journal manuscripts were published and two more manuscripts are presently under review. Twelve conference abstracts were published including Society for Biomaterials, Midwestern Tissue Engineering Consortium, European Materials Research Society, and Tissue Engineering and Regenerative Medicine International Society North America. The list of published manuscript is follows: 1) A. C. Jayasuriya, A. Bhat. Optimization of scaled-up Chitosan Microparticles for Bone Regeneration, Biomed Mater, 4(5):55006, 2009. 2) A. C. Jayasuriya, A. Bhat. Fabrication and Characterization of Novel Hybrid Organic/Inorganic Microparticles to apply in Bone Regeneration, J Biomed Mater Res A. 93(4):1280-8, 2010. 3) A. C. Jayasuriya, A. Bhat. Mesenchymal stem cell function on hybrid organic/inorganic microparticles in vitro, J Tissue Eng Regen. Med 4(5):340-8, 2010. 4) A. Bhat, M. Dreifke, C. Gomez, Y. Kandimalla, N. A. Ebraheim, A. C. Jayasuriya. Evaluation of cross-linked chitosan microparticles for bone regeneration. J Tissue Eng Regen Med 4(7):532-542, 2010. 5) A. C. Jayasuriya, S. Kibbe. Rapid biomineralization of chitosan microparticles to apply in bone regeneration. J Mater Sci Mater Med. 21(2):393-8, 2010. 6) A. C. Jayasuriya, K. J. Mauch, In vitro degradation behavior of chitosan based hybrid microparticles, Journal of Biomedical Science and Engineering, 4(5):383-390, 2011. 7) A. Aryaei, A. H. Jayatissa, A. C. Jayasuriya, Nano and Micro Mechanical Properties of Cross-Linked Chitosan Samples. Journal of the Mechanical Behavior of Biomedical Materials J Mech Behav Biomed Mater. 5(1):82-9, 2012. 8) A. C. Jayasuriya, K. J. Mauch, N. A. Ebraheim. Fabrication and Characterization of Injectable Biomaterials for Biomedical Applications, Advanced Materials Research: 383-390: 4065-4069, 2012. 9) M. Dreifke, N. A. Ebraheim, A. C. Jayasuriya. Investigation of Potential Injectable Polymeric Biomaterials for Bone Regeneration, J Biomed Mater Res A 2013 Feb 11. doi: 10.1002/jbm.a.34521. [Epub ahead of print]. 10) V. P. Mantripragada, B. Lecka-Czernik, N. A. Ebraheim, A. C. Jayasuriya. An overview of recent advances in orthopedic and craniofacial implants, J Biomed Mater Res A (In publish). 11) A. Bhat, R. M. Wooten, A. C. Jayasuriya. Secretion of growth factors from macrophages when cultured with microparticles, J Biomed Mater Res A 2013 Apr 2. doi: 10.1002/jbm.a.34604. [Epub ahead of print].
