title: Sequential delivery of immunomodulatory cytokines to facilitate the M1-to-M2 transition of macrophages and enhance vascularization of bone scaffolds.
abstract: In normal tissue repair, macrophages exhibit a pro-inflammatory phenotype (M1) at early stages and a pro-healing phenotype (M2) at later stages. We have previously shown that M1 macrophages initiate angiogenesis while M2 macrophages promote vessel maturation. Therefore, we reasoned that scaffolds that promote sequential M1 and M2 polarization of infiltrating macrophages should result in enhanced angiogenesis and healing. To this end, we first analyzed the in vitro kinetics of macrophage phenotype switch using flow cytometry, gene expression, and cytokine secretion analysis. Then, we designed scaffolds for bone regeneration based on modifications of decellularized bone for a short release of interferon-gamma (IFNg) to promote the M1 phenotype, followed by a more sustained release of interleukin-4 (IL4) to promote the M2 phenotype. To achieve this sequential release profile, IFNg was physically adsorbed onto the scaffolds, while IL4 was attached via biotin-streptavidin binding. Interestingly, despite the strong interactions between biotin and streptavidin, release studies showed that biotinylated IL4 was released over 6 days. These scaffolds promoted sequential M1 and M2 polarization of primary human macrophages as measured by gene expression of ten M1 and M2 markers and secretion of four cytokines, although the overlapping phases of IFNg and IL4 release tempered polarization to some extent. Murine subcutaneous implantation model showed increased vascularization in scaffolds releasing IFNg compared to controls. This study demonstrates that scaffolds for tissue engineering can be designed to harness the angiogenic behavior of host macrophages towards scaffold vascularization.
authors.affiliation: Department of Biomedical Engineering, Columbia University, 622 West 168th Street, VC12-234, New York, NY 10032, USA; School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut St., Philadelphia 19104, PA, USA. Electronic address: kspiller@coe.drexel.edu.
authors.forename: Kara L
authors.initials: KL
authors.lastname: Spiller
authors.affiliation: School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut St., Philadelphia 19104, PA, USA. Electronic address: sn463@drexel.edu.
authors.forename: Sina
authors.initials: S
authors.lastname: Nassiri
authors.affiliation: School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut St., Philadelphia 19104, PA, USA. Electronic address: cem73@drexel.edu.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Witherel
authors.affiliation: Department of Biomedical Engineering, Columbia University, 622 West 168th Street, VC12-234, New York, NY 10032, USA. Electronic address: rachel.anfang@gmail.com.
authors.forename: Rachel R
authors.initials: RR
authors.lastname: Anfang
authors.affiliation: Department of Biomedical Engineering, Columbia University, 622 West 168th Street, VC12-234, New York, NY 10032, USA. Electronic address: jjn2113@columbia.edu.
authors.forename: Johnathan
authors.initials: J
authors.lastname: Ng
authors.affiliation: Department of Biomedical Engineering, Columbia University, 622 West 168th Street, VC12-234, New York, NY 10032, USA. Electronic address: krn2111@columbia.edu.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Nakazawa
authors.affiliation: School of Biomedical Engineering, Science and Health Systems, Drexel University, 3141 Chestnut St., Philadelphia 19104, PA, USA.
authors.forename: Tony
authors.initials: T
authors.lastname: Yu
authors.affiliation: Department of Biomedical Engineering, Columbia University, 622 West 168th Street, VC12-234, New York, NY 10032, USA. Electronic address: gv2131@columbia.edu.
authors.forename: Gordana
authors.initials: G
authors.lastname: Vunjak-Novakovic
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001842:Bone and Bones / Q000098:blood supply*; D016764:Cell Polarity / Q000187:drug effects*; D016207:Cytokines / Q000378:metabolism / Q000494:pharmacology*; D016503:Drug Delivery Systems; D005260:Female; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D007155:Immunologic Factors / Q000494:pharmacology*; D020007:Implants, Experimental; D007700:Kinetics; D008264:Macrophages / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D010641:Phenotype; D040521:Subcutaneous Tissue / Q000187:drug effects; D013997:Time Factors; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D015415:Biomarkers; D016207:Cytokines; D007155:Immunologic Factors
keywords: Bone; Cytokines; Immunomodulation; Macrophages; Regenerative medicine; Vascularization