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Isali I, McClellan P, Shankar E, Gupta S, Jain M, Anderson JM, Hijaz A, Akkus O. Genipin guides and sustains the polarization of macrophages to the pro-regenerative M2 subtype via activation of the pSTAT6-PPAR-gamma pathway. Acta Biomater 2021; 131:198-210. [PMID: 34224892 DOI: 10.1016/j.actbio.2021.06.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/18/2021] [Accepted: 06/28/2021] [Indexed: 12/21/2022]
Abstract
M2 macrophages are associated with deposition of interstitial collagen and other extracellular matrix proteins during the course wound healing and also inflammatory response to biomaterials. Developing advanced biomaterials to promote the M2 subtype may be an effective way to improve tissue reinforcement surgery outcomes. In this study, the effect of genipin, a naturally derived crosslinking agent, on M0 → M2-polarization was investigated. Genipin was introduced either indirectly by seeding cells on aligned collagen biotextiles that are crosslinked by the agent or in soluble form by direct addition to the culture medium. Cellular elongation effects on macrophage polarization induced by the collagen biotextile were also investigated as a potential inducer of macrophage polarization. M0 and M2 macrophages demonstrated significant elongation on the surface of aligned collagen threads, while cells of the M1 subtype-maintained a round phenotype. M0 → M2 polarization, as reflected by arginase and Ym-1 production, was observed on collagen threads only when the threads were crosslinked by genipin, implicating genipin as a more potent inducer of the regenerative phenotype compared to cytoskeletal elongation. The addition of genipin to the culture medium directly also drove the emergence of pro-regenerative phenotype as measured by the markers (arginase and Ym-1) and through the activation of the pSTAT6-PPAR-gamma pathway. This study indicates that genipin-crosslinked collagen biotextiles can be used as a delivery platform to promote regenerative response after biomaterial implantation. STATEMENT OF SIGNIFICANCE: The immune response is one of the key determinants of tissue repair and regeneration rate, and outcome. The M2 macrophage subtype is known to resolve the inflammatory response and support tissue repair by producing pro-regenerative factors. Therefore, a biomaterial that promotes M2 sub-type can be a viable strategy to enhance tissue regeneration. In this study, we investigated genipin-crosslinked electrochemically aligned collagen biotextiles for their capacity to induce pro-regenerative polarization of M0 macrophages. The results demonstrated that genipin, rather than matrix-induced cellular elongation, was responsible for M0 → M2 polarization in the absence of other bioinductive factors and maintaining the M2 polarized status of macrophages. Furthermore, we identified that genipin polarizes the M2 macrophage phenotype via activation of the pSTAT6-PPAR-gamma pathway.
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Affiliation(s)
- Ilaha Isali
- Department of Urology, University Hospitals Cleveland Medical Center, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Phillip McClellan
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Eswar Shankar
- Department of Urology, University Hospitals Cleveland Medical Center, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sanjay Gupta
- Department of Urology, University Hospitals Cleveland Medical Center, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Mukesh Jain
- Harrington Discovery Institute and the Harrington Heart and Vascular Institute, University Hospitals Cleveland Medical Center, and the Case Cardiovascular Research Institute, Case Western Reserve University, USA
| | - James M Anderson
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Macromolecular Science, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Adonis Hijaz
- Department of Urology, University Hospitals Cleveland Medical Center, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ozan Akkus
- Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA; Department of Orthopedics, Case Western Reserve University, Cleveland, OH 44106, USA.
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