a-facile-synthesis-upconversion-metal-organic-framework

A Facile Synthesis of Upconversion Metal-Organic Framework Heterodimers

The synthesis of nanostructures with asymmetric configurations in terms of both geometries and compositions has attracted extensive interest in recent ...

longitudinal-micro-computed-tomography-image-analysis-for-user

Longitudinal Micro-Computed Tomography Image Analysis for User-Defined Region of Interest in Critical-Sized Bone Defects

Micro-computed tomography (&#181;CT) imaging analysis of bone volume is a necessary quantitative tool for investigating bone regeneration potential and ...

CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology (NCNST)

University of Rochester Medical Center

Implant-associated osteomyelitis remains a major orthopaedic problem. As neutrophil swarming to the surgical site is a critical host response to prevent infection, visualization and quantification of this dynamic behavior at the native microenvironment of infection will elucidate previously unrecognized mechanisms central to understanding the host response. We recently developed longitudinal intravital imaging of the bone marrow (LIMB) to visualize fluorescent  on a contaminated transfemoral implant and host cells in live mice, which allows for direct visualization of bacteria colonization of the implant and host cellular responses using two-photon laser scanning microscopy. To the end of rigorous and reproducible quantitative outcomes of neutrophil swarming kinetics in this model, we developed a protocol for robust segmentation, tracking, and quantifications of neutrophil dynamics adapted from Trainable Weka Segmentation and TrackMate, two readily available Fiji/ImageJ plugins. In this work,  mice with tdTomato expressing neutrophils received a transfemoral pin with or without ECFP-expressing USA300 methicillin-resistant  (MRSA) to obtain 30-minute LIMB videos at 2-, 4-, and 6-hours post-implantation. The developed semi-automated neutrophil tracking protocol was executed independently by two users to quantify the distance, displacement, speed, velocity, and directionality of the target cells. The results revealed high inter-reader reliability for all outcomes (ICC > 0.98; p > 0.05). Consistent with the established paradigm on increased neutrophil swarming during active infection, the results also demonstrated increased neutrophil speed and velocity at all measured time points, and increased displacement at later time points (6 hours) in infected versus uninfected mice (p < 0.05). Neutrophils and bacteria also exhibit directionality during migration in the infected mice. The semi-automated cell tracking protocol provides a streamlined approach to robustly identify and track individual cells across diverse experimental settings and eliminates inter-observer variability.

A semi-automated cell tracking protocol for quantitative analyses of neutrophil swarming to sterile and  contaminated bone implants in a mouse femur model.

Implant-associated osteomyelitis remains a major orthopaedic problem. As neutrophil swarming to the surgical site is a critical host response to prevent infection, visualization and quantification of this dynamic behavior at the native microenvironment of infection will elucidate previously unrecognized mechanisms central to understanding the host response. We recently developed longitudinal intravital imaging of the bone marrow (LIMB) to visualize host cells and fluorescent S. aureus on a contaminated transfemoral implant in live mice, which allows for direct visualization of bacteria colonization of the implant and host cellular responses using two-photon laser scanning microscopy. To the end of rigorous and reproducible quantitative outcomes of neutrophil swarming kinetics in this model, we developed a protocol for robust segmentation, tracking, and quantifications of neutrophil dynamics adapted from Trainable Weka Segmentation and TrackMate, two readily available Fiji/ImageJ plugins. In this work, Catchup mice with tdTomato expressing neutrophils received a transfemoral pin with or without ECFP/EGFP-expressing USA300 methicillin-resistant Staphylococcus aureus (MRSA) to obtain 30-minute LIMB videos at 2-, 4-, and 6-hours post-implantation. The developed semi-automated neutrophil tracking protocol was executed independently by two users to quantify the distance, displacement, speed, velocity, and directionality of the target cells. The results revealed high inter-user reliability for all outcomes (ICC > 0.96; p > 0.05). Consistent with the established paradigm on increased neutrophil swarming during active infection, the results also demonstrated increased neutrophil speed and velocity at all measured time points, and increased displacement at later time points (6 hours) in infected versus uninfected mice (p < 0.05). Neutrophils and bacteria also exhibit directionality during migration in the infected mice. The semi-automated cell tracking protocol provides a streamlined approach to robustly identify and track individual cells across diverse experimental settings and eliminates inter-observer variability.

A semi-automated cell tracking protocol for quantitative analyses of neutrophil swarming to sterile and S. aureus contaminated bone implants in a mouse femur model.

Regenerating critical-sized long bone defects poses substantial challenges due to limitations of autografts and processed allografts. Biomaterial scaffolds offer versatile alternatives, yet their effectiveness is often constrained by their limited innate osteoinductivity. While growth factors and cells can enhance osteoinduction, the inclusion of biologics in biomaterial scaffolds creates regulatory challenges for clinical translation. To address this, here we describe three-dimensional (3D) printed polycaprolactone (PCL) scaffolds for temporally controlled delivery of osteoimmunomodulatory amorphous calcium phosphate-chitosan nanoparticles (ACPC-NP). , the ACPC-NP exhibit concentration dependent effects on osteoblasts, monocytes, and osteoclasts. At increasing concentrations up to 500 μg/ml, these nanoparticles stimulate osteogenesis, modulate M2/M1 macrophage polarization, and inhibit osteoclast maturation and activity. Leveraging these concentration-dependent effects  through temporally controlled release of ACPC-NP from 3D-printed PCL scaffolds, we observe the complete regeneration and the restoration of biomechanical strength of critically sized radial defects in rats. Such healing is absent in defects implanted with bare PCL scaffolds or those loaded with calcium-phosphate microparticles. The tunable osteoimmunomodulation by the NP underscores the translational potential of this technology to yield structurally sound and functionally robust bone regeneration outcomes.

ArticleTotal : 2	Year
Publication title
Publication title Cited by 1	2025

Article	Year
A semi-automated cell tracking protocol for quantitative analyses of neutrophil swarming to sterile and contaminated bone implants in a mouse femur model. bioRxiv : the preprint server for biology\| PubMed ID: 38105961	2023
A semi-automated cell tracking protocol for quantitative analyses of neutrophil swarming to sterile and S. aureus contaminated bone implants in a mouse femur model. PloS one\| PubMed ID: 38900759	2024
Dose-dependent osteoimmunomodulatory effects of amorphous calcium phosphate nanoparticles promote 3D-printed scaffold-mediated bone regeneration. Bioactive materials\| PubMed ID: 40487242	2025

Bei Liu

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