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Juhl OJ, Merife AB, Zhang Y, Lemmon CA, Donahue HJ. Hydroxyapatite Particle Density Regulates Osteoblastic Differentiation Through β-Catenin Translocation. Front Bioeng Biotechnol 2021; 8:591084. [PMID: 33490047 PMCID: PMC7820766 DOI: 10.3389/fbioe.2020.591084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 12/08/2020] [Indexed: 01/09/2023] Open
Abstract
Substrate surface characteristics such as roughness, wettability and particle density are well-known contributors of a substrate's overall osteogenic potential. These characteristics are known to regulate cell mechanics as well as induce changes in cell stiffness, cell adhesions, and cytoskeletal structure. Pro-osteogenic particles, such as hydroxyapatite, are often incorporated into a substrate to enhance the substrates osteogenic potential. However, it is unknown which substrate characteristic is the key regulator of osteogenesis. This is partly due to the lack of understanding of how these substrate surface characteristics are transduced by cells. In this study substrates composed of polycaprolactone (PCL) and carbonated hydroxyapatite particles (HAp) were synthesized. HAp concentration was varied, and a range of surface characteristics created. The effect of each substrate characteristic on osteoblastic differentiation was then examined. We found that, of the characteristics examined, only HAp density, and indeed a specific density (85 particles/cm2), significantly increased osteoblastic differentiation. Further, an increase in focal adhesion maturation and turnover was observed in cells cultured on this substrate. Moreover, β-catenin translocation from the membrane bound cell fraction to the nucleus was more rapid in cells on the 85 particle/cm2 substrate compared to cells on tissue culture polystyrene. Together, these data suggest that particle density is one pivotal factor in determining a substrates overall osteogenic potential. Additionally, the observed increase in osteoblastic differentiation is a at least partly the result of β-catenin translocation and transcriptional activity suggesting a β-catenin mediated mechanism by which substrate surface characteristics are transduced.
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Affiliation(s)
- Otto J Juhl
- Department of Biomedical Engineering and Institute for Engineering and Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | - Anna-Blessing Merife
- Department of Biomedical Engineering and Institute for Engineering and Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | - Yue Zhang
- Department of Biomedical Engineering and Institute for Engineering and Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | - Christopher A Lemmon
- Department of Biomedical Engineering and Institute for Engineering and Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | - Henry J Donahue
- Department of Biomedical Engineering and Institute for Engineering and Medicine, Virginia Commonwealth University, Richmond, VA, United States
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Juhl O, Zhao N, Merife AB, Cohen D, Friedman M, Zhang Y, Schwartz Z, Wang Y, Donahue H. Aptamer-Functionalized Fibrin Hydrogel Improves Vascular Endothelial Growth Factor Release Kinetics and Enhances Angiogenesis and Osteogenesis in Critically Sized Cranial Defects. ACS Biomater Sci Eng 2019; 5:6152-6160. [PMID: 32190730 PMCID: PMC7079287 DOI: 10.1021/acsbiomaterials.9b01175] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
An aging population, decreased activity levels and increased combat injuries, have led to an increase in critical sized bone defects. As more defects are treated using allografts, which is the current standard of care, the deficiencies of allografts are becoming more evident. Allografts lack the angiogenic potential to induce sufficient vasculogenesis to counteract the hypoxic environment associated with critical sized bone defects. In this study, aptamer-functionalized fibrin hydrogels (AFH), engineered to release vascular endothelial growth factor (VEGF), were evaluated for their material properties, growth factor release kinetics, and angiogenic and osteogenic potential in vivo. Aptamer functionalization to native fibrin did not result in significant changes in biocompatibility or hydrogel gelation. However, aptamer functionalization of fibrin did improve the release kinetics of VEGF from AFH and, when compared to FH, reduced the diffusivity and extended the release of VEGF several days longer. VEGF released from AFH, in vivo, increased vascularization to a greater degree, relative to VEGF released from FH, in a murine critical-sized cranial defect. Defects treated with AFH loaded with VEGF, relative to nonhydrogel loaded controls, showed a nominal increase in osteogenesis. Together, these data suggest that AFH more efficiently incorporates and retains VEGF in vitro and in vivo, which then enhances angiogenesis and osteogenesis to a greater extent in vivo than FH.
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Affiliation(s)
- Otto Juhl
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23220, United States
| | - Nan Zhao
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Anna-Blessing Merife
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23220, United States
| | - David Cohen
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23220, United States
| | - Michael Friedman
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23220, United States
| | - Yue Zhang
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23220, United States
| | - Zvi Schwartz
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23220, United States
| | - Yong Wang
- Department of Biomedical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Henry Donahue
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia 23220, United States
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