Nano-particle mediated M2 macrophage polarization enhances bone formation and MSC osteogenesis in an IL-10 dependent manner

Abstract

Engineering a pro-regenerative immune response following scaffold implantation is integral to functional tissue regeneration. The immune response to implanted biomaterials is determined by multiple factors, including biophysical cues such as material stiffness, topography and particle size. In this study we developed an immune modulating scaffold for bone defect healing containing bone mimetic nano hydroxyapatite particles (BMnP). We first demonstrate that, in contrast to commercially available micron-sized hydroxyapatite particles, in-house generated BMnP preferentially polarize human macrophages towards an M2 phenotype, activate the transcription factor cMaf and specifically enhance production of the anti-inflammatory cytokine, IL-10. Furthermore, nano-particle treated macrophages enhance mesenchymal stem cell (MSC) osteogenesis in vitro and this occurs in an IL-10 dependent manner, demonstrating a direct proosteogenic role for this cytokine. BMnPs were also capable of driving pro-angiogenic responses in human macrophages and HUVECs. Characterization of immune cell subsets following incorporation of functionalized scaffolds into a rat femoral defect model revealed a similar profile, with micron-sized hydroxyapatite functionalized scaffolds eliciting pro-inflammatory responses characterized by infiltrating T cells and elevated expression of M1 macrophages markers compared to BMnP functionalized scaffolds which promoted M2 macrophage polarization, tissue vascularization and increased bone volume. Taken together these results demonstrate that nanosized Hydroxyapatite has immunomodulatory potential and is capable of directing antiinflammatory innate immune-mediated responses that are associated with tissue repair and regeneration.

Non-viral Gene Delivery of Interleukin-1 Receptor Antagonist Using Collagen-Hydroxyapatite Scaffold Protects Rat BM-MSCs From IL-1β-Mediated Inhibition of Osteogenesis

“…Similarly, it is likely that different non-viral gene delivery vectors have different propensities for stimulating a pro- or anti-inflammatory response, which might enhance or suppress the effect of their therapeutic cargo. This is supported by a recent study reporting that the size and shape of hydroxyapatite particles can be tuned to stimulate M2 macrophage polarization ( Mahon et al, 2020 ). A limited assessment might be possible to determine the effect of different non-viral gene delivery vectors on M1/M2 macrophage polarization; however, in vivo assessment would ultimately be required to better understand the relationship between non-viral gene delivery vectors and the immune response that they trigger.…”

Development of a New Bone‐Mimetic Surface Treatment Platform: Nanoneedle Hydroxyapatite (nnHA) Coating

“…This is based on the fact that such amorphous surface layer generally forms for nanocrystalline HA samples synthesized by direct precipitation methods at ambient temperature. [48,72,73] It can also be seen that the resonance of the 31 P SP MAS ssNMR spectrum of the nnHA scaffold (FWHM = 2.0 ± 0.2 ppm) is largely wider than that of a stoichiometric hydroxyapatite sample such as iHA powder (FWHM = 0.8 ± 0.1 ppm) ( Figure 3A). Based on the above, the hydroxyapatite nanoparticles of the nnHA MEW scaffold, Figure 3.…”

“…[45][46][47] Appropriately sized nHA particles can also preferentially polarize human macrophages toward an M2 phenotype and enhance production of the anti-inflammatory cytokines such as IL-10. [48] The role of HA particle size has also been investigated in the 3D printing of composite polycaprolactone-HA (PCL-HA) blends, with enhanced proliferation and alkaline phosphatase (ALP) activity of MSCs seen with nanoparticles compared to microparticles. [49] Remarkably, particle size has not only been shown to be an important cue for MSC osteogenesis but also plays a role in suppressing undesired cellular outcomes in bone.…”

Calcium silicate bioactive ceramics induce osteogenesis through oncostatin M

“…It has been reported that biomaterials with special components and surface topographies can also induce macrophage polarization, switching from pro-inflammatory M1 to anti-inflammatory M2 types [ 29 ]. In addition, the polarization induced by the materials may be closely related to their osteogenic activity.…”