Electrospun Fiber Mesh for High-Resolution Measurements of Oxygen Tension in Cranial Bone Defect Repair

Abstract

Tissue oxygenation is one of the key determining factors in bone repair and bone tissue engineering. Adequate tissue oxygenation is essential for survival and differentiation of the boneforming cells and ultimately the success of bone tissue regeneration. Two-photon phosphorescence lifetime microscopy (2PLM) has been successfully applied in the past to image oxygen distributions in tissue with high spatial resolution. However, delivery of phosphorescent probes into avascular compartments, such as those formed during early bone defect healing, poses significant problems. Here we report a multifunctional oxygen-reporting fibrous matrix fabricated through encapsulation of a hydrophilic oxygen-sensitive, two-photon excitable phosphorescent probe PtP-C343 in the core of fibers during coaxial electrospinning. The oxygen-sensitive fibers support bone marrow stromal cell (BMSC) growth and differentiation, while at the same time enable real-time high-resolution probing of partial pressures of oxygen (pO 2 ) via 2PLM. The hydrophilicity of the probe further facilitates its gradual release into the nearby microenvironment, allowing fibers to act as a vehicle for probe delivery into the healing tissue. In conjunction with a cranial defect window chamber model, which permits simultaneous imaging of the bone and neovasculature in vivo via two-photon laser scanning microscopy (2PLSM), the oxygen reporting fibers provide a useful tool for minimally invasive, high-resolution, real-time 3D mapping of tissue oxygenation during bone defect healing, facilitating studies aimed at understanding the healing process and advancing design of tissue engineered constructs for enhanced bone repair and regeneration.

Multiparametric Optical Bioimaging Reveals the Fate of Epoxy Crosslinked Biomeshes in the Mouse Subcutaneous Implantation Model

“…To test this, we used PLIM microscopy with the help of O 2 -sensitive nanosensors. Recent success in design of O 2 -and pH-sensing 'hybrid' tissue engineering materials (Jenkins et al, 2015;Yazgan et al, 2017;O'Donnell et al, 2018;Roussakis et al, 2019;Schilling et al, 2019) prompted us to stain the pericardial biomeshes with O 2sensitive polymer nanoparticles. We hypothesized that charged nanoparticles could experience hydrophobic interactions and provide strong non-specific adsorption with the crosslinker or the polypeptide chains of the DBPs.…”

Luminescence lifetime imaging of three-dimensional biological objects

“…O 2 -sensitive 'biosensor scaffolds' (i.e. tissue engineering scaffolds containing phosphorescent O 2 -sensing dye) have been employed for the imaging of brain slices, scaffold-colonizing cancer cell aggregates and bone regeneration constructs (Jenkins et al, 2015;Schilling et al, 2019;Trampe et al, 2018;Xue et al, 2013Xue et al, , 2016Yazgan et al, 2017). Moreover, multiplexed 3D imaging, combining O 2 imaging with live-cell labeling, has enabled the tracing of hypoxia-dependent cell differentiation and anticancer drug action (Jenkins et al, 2015).…”

Electrospun core-shell nanofibers with encapsulated enamel matrix derivative for guided periodontal tissue regeneration

“…The conventional type of electrospinning utilizes a single polymer, while newer methods can create fibers with multiple components 21) . One such technique is coaxial electrospinning, which produces "core-shell" fibers made of an inner "core" containing a drug, growth factor, and/or protein, and an outer "shell" polymer which provides mechanical properties 22,23) . These core-shell nanofibers allow for direct incorporation of biologically active molecules into the core component, enabling controlled delivery of a desired drug or protein 22,23) .…”