Interleukin‐4 overexpressing mesenchymal stem cells within gelatin‐based microribbon hydrogels enhance bone healing in a murine long bone critical‐size defect model

Abstract

Mesenchymal stem cell (MSC)‐based therapy is a promising strategy for bone repair. Furthermore, the innate immune system, and specifically macrophages, plays a crucial role in the differentiation and activation of MSCs. The anti‐inflammatory cytokine Interleukin‐4 (IL‐4) converts pro‐inflammatory M1 macrophages into a tissue regenerative M2 phenotype, which enhances MSC differentiation and function. We developed lentivirus‐transduced IL‐4 overexpressing MSCs (IL‐4 MSCs) that continuously produce IL‐4 and polarize macrophages toward an M2 phenotype. In the current study, we investigated the potential of IL‐4 MSCs delivered using a macroporous gelatin‐based microribbon (μRB) scaffold for healing of critical‐size long bone defects in Mice. IL‐4 MSCs within μRBs enhanced M2 marker expression without inhibiting M1 marker expression in the early phase, and increased macrophage migration into the scaffold. Six weeks after establishing the bone defect, IL‐4 MSCs within μRBs enhanced bone formation and helped bridge the long bone defect. IL‐4 MSCs delivered using macroporous μRB scaffold is potentially a valuable strategy for the treatment of critical‐size long bone defects.

PDGF-BB and IL-4 co-overexpression is a potential strategy to enhance mesenchymal stem cell-based bone regeneration

“…Although biomaterials have been used as carriers for these soluble factors, local delivery remains a problem due to the biodegradability of the materials, release profiles, and potential for adverse inflammatory and immunological reactions [12,13], often leading to a short biological half-life. Recently, novel scaffold technologies for delivery of cells and biologics which could protect the cells as well as stimulate endogenous recruitment of cells to support osteogenesis via controlled delivery of biologics have been developed [12,[14][15][16]. However, as an alternative strategy, regional gene therapy could not only provide a time-and dose-controlled delivery of growth factors, cytokines, or chemokines for inducing bone formation [9,17,18] but also provide the source of potential cells that could facilitate the process more efficiently.…”

“…However, as an alternative strategy, regional gene therapy could not only provide a time-and dose-controlled delivery of growth factors, cytokines, or chemokines for inducing bone formation [9,17,18] but also provide the source of potential cells that could facilitate the process more efficiently. The strategy of genetically modified cells appears to be a viable and more sustained biomaterial drug delivery system for bone regeneration [12,15,16].…”

Different Effects of Intramedullary Injection of Mesenchymal Stem Cells During the Acute vs. Chronic Inflammatory Phase on Bone Healing in the Murine Continuous Polyethylene Particle Infusion Model

“…Macrophages were identified by immunofluorescence staining with rat anti-mouse F4/80 monoclonal antibody (CI: A3-1, Bio-Rad) followed by Alexa Fluor ® 594 conjugated goat anti-rat IgG (Invitrogen, Carlsbad, CA, United States). To identify the M1 pro-inflammatory macrophage phenotype, sections were also stained with rabbit anti-mouse inducible nitric oxide synthase (iNOS) polyclonal antibody (Abcum, Cambridge, United Kingdom) followed by Alexa Fluor ® 488 conjugated goat anti-rabbit IgG (Invitrogen, Carlsbad, CA, United States) ( Ueno et al, 2020 ). The slides were then mounted with ProLong Gold Antifade Mount with DAPI (Life Technologies, Grand Island, NY) and the photomicrographs were observed under a fluorescence microscope (Digital Microscope, Keyence, IL).…”

“…In different sections, osteoblast-like cells ( Sato et al, 2015 ; Lin et al, 2016 ; Nabeshima et al, 2017 ) were identified using anti-alkaline phosphatase (ALP) antibody (1-Step TM NBT/BCIP Substrate Solution, Thermo Scientific, Rockford, IL). Using the entire image of each specimen with x100 magnification, the percentage of brown, positively stained area for ALP was quantified based on the entire area of each section measured using ImageJ software ( Ueno et al, 2020 ). The color threshold of ALP staining positive area was determined by consensus of three of the investigators.…”

<p>Inflammation, Bone Healing and Osteonecrosis: From Bedside to Bench</p>

“…41,48,[57][58][59][60][61][62] This approach is one of the great interests of our laboratory's treatment of chronic bone defects and osteonecrosis. 1,63 Other potential immunotherapeutic approaches include delivery of IL-13, IL-10, IL-1Ra, TNFsR, etc. 64…”