Instructive biomaterials for controlling cellular response and second harmonic generation imaging for quantitative characterization of collagen

Biomaterial - biological system interaction triggers complex response to the implanted materials. The response includes series of overlapping processes as coagulation, inflammation and wound healing. Immune cells interaction with the material interface during these processed play crucial role in successful outcome of the implanted biomaterials in tissue engineering, wound healing, and artificial organs. Biomaterial type and microenvironment influence host response. Here, we show ability to reprogram immune cell as macrophages towards either pro-inflammatory or anti-inflammatory response through polystyrene latex beads bearing different functional groups. Although there is a plethora of evidence illustrating how biomaterials influence functions of macrophages, there is a paucity of studies investigating the effects of polymer materials on both polarizations and phenotype differentiation. During the wound healing stage polymer can also influence healing quality and time through affecting formation of proteins as collagen. The quality of the healed wound depends on collagen organization. Achieving random collagen deposition that more closely resembles young, healthy skin would be a vast improvement upon the imperfections of the natural wound healing process and the integration of tissue engineered scaffolds. Collagen secreted around implant can play crucial role in the successful outcome of the implanted devices such as sensors or delivery devices. Our goal is to affect cells responsible for formation of collagen and its orientation during the wound healing process through polymer substrates. The library of materials used here is based on the basic amino acid arginine. Our results demonstrate the ability to exert a level of control over cellular responses through biomaterials and the potential to attain the desired outcome with exposure to these materials in wound healing and tissue engineering. Second harmonic generation imaging was used for quantitative characterization of collagen fiber deposited by cells. Non-centrosymmetric helical structure of collagen fibers allow us to image without any labels and minimum damage. One of the main applications of SHG microscopy has been imaging collagen fibers and determining fiber organization and parameters related to the second-order nonlinear susceptibility. We have used SHG microscopy to assess the quality of deposited collagen through quantitative analysis of collagen orientation and structure

Design of a smartphone plastic optical fiber chemical sensor for hydrogen sulfide detection

We present a low-cost, handheld plastic optical fiber (POF) sensor for hydrogen sulfide (H2S) detection integrated onto a smartphone. The sensor uses smartphone flashlight as a source and camera as a pixel-based intensity detector. The POF is interconnected to the smartphone with a 3-D-printed connector on both source/detector sides. The sensing mechanism is embedded in the fiber link, making the system an all-fiber smartphone architecture. A mobile application handles data acquisition on the Android operative system. The sensor is functionalized for H2S detection through silver deposition on the POF outer surface. Experiments demonstrate the feasibility of the sensor system as the presence of H2S is successfully measured through an increase of optical losses through the POF link. This cost-effective, scalable, and compact sensor is promising for application in environmental sensing

Brillouin spectroscopy and radiography for assessment of viscoelastic and regenerative properties of mammalian bones

Biomechanical properties of mammalian bones, such as strength, toughness, and plasticity, are essential for understanding how microscopic-scale mechanical features can link to macroscale bones’ strength and fracture resistance. We employ Brillouin light scattering (BLS) microspectroscopy for local assessment of elastic properties of bones under compression and the efficacy of the tissue engineering approach based on heparin-conjugated fibrin (HCF) hydrogels, bone morphogenic proteins, and osteogenic stem cells in the regeneration of the bone tissues. BLS is noninvasive and label-free modality for probing viscoelastic properties of tissues that can give information on structure-function properties of normal and pathological tissues. Results showed that MCS and BPMs are critically important for regeneration of elastic and viscous properties, respectively, HCF gels containing combination of all factors had the best effect with complete defect regeneration at week nine after the implantation of bone grafts and that the bones with fully consolidated fractures have higher values of elastic moduli compared with defective bone

5 Patient specific in situ 3D printing

Abstract In this chapter, we will focus on how 3D printer technology is transforming traditional medicine into a personalized approach, giving an overview of the technology advancement and its clinical applications. First, we will discuss why personalization in medicine is required, its benefits for the patients and how 3D printing technology can address this need for the patient specific treatment solutions. Basic capabilities of 3D printers and the three most common 3D printing technologies used in medical applications will be covered as well. The second section focuses on current and potential medical applications of 3D printing. The main medical applications can be arranged into three categories: (1) 3D bioprinting of organs and tissues; (2) patient specific medical devices: prosthetics and implants; and (3) 3D models for surgical preparation. Here, we will discuss 3D printing of living cells, in situ 3D bioprinting directly to the defect site, some successful cases of the implantation of various 3D constructs and the production of precise anatomical models for surgical trainings. Lastly, we will highlight challenges and emerging technology developments for the printing of functional organ constructs and medical devices

Instructive biomaterials for controlling cellular response and second harmonic generation imaging for quantitative characterization of collagen

Biomaterial - biological system interaction triggers complex response to the implanted materials. The response includes series of overlapping processes as coagulation, inflammation and wound healing. Immune cells interaction with the material interface during these processed play crucial role in successful outcome of the implanted biomaterials in tissue engineering, wound healing, and artificial organs. Biomaterial type and microenvironment influence host response. Here, we show ability to reprogram immune cell as macrophages towards either pro-inflammatory or anti-inflammatory response through polystyrene latex beads bearing different functional groups. Although there is a plethora of evidence illustrating how biomaterials influence functions of macrophages, there is a paucity of studies investigating the effects of polymer materials on both polarizations and phenotype differentiation. During the wound healing stage polymer can also influence healing quality and time through affecting formation of proteins as collagen. The quality of the healed wound depends on collagen organization. Achieving random collagen deposition that more closely resembles young, healthy skin would be a vast improvement upon the imperfections of the natural wound healing process and the integration of tissue engineered scaffolds. Collagen secreted around implant can play crucial role in the successful outcome of the implanted devices such as sensors or delivery devices. Our goal is to affect cells responsible for formation of collagen and its orientation during the wound healing process through polymer substrates. The library of materials used here is based on the basic amino acid arginine. Our results demonstrate the ability to exert a level of control over cellular responses through biomaterials and the potential to attain the desired outcome with exposure to these materials in wound healing and tissue engineering. Second harmonic generation imaging was used for quantitative characterization of collagen fiber deposited by cells. Non-centrosymmetric helical structure of collagen fibers allow us to image without any labels and minimum damage. One of the main applications of SHG microscopy has been imaging collagen fibers and determining fiber organization and parameters related to the second-order nonlinear susceptibility. We have used SHG microscopy to assess the quality of deposited collagen through quantitative analysis of collagen orientation and structure.</p

POLY-L-ARGININE MODIFICATIONS ALTER THE ORGANIZATION AND SECRETION OF COLLAGEN IN SKH1-E MICE

Functionalized biomaterials interface with tissue upon implantation. There is a growing need to understand how materials properties influence this interaction so that efficient tissue engineering systems can be developed. In this study, we characterize collagen organization in response to functionalized glass beads implanted in SKH1-E mice. Poly-L-arginine (PLR) was modified with arginine derivatives to create a functionalized surface and was coated on glass beads. Tissue sections were removed 28 days post-implantation and were imaged using second harmonic generation (SHG) microscopy. These chemical modifications were able to alter the collagen dis tribution from highly aligned to disordered (17 ± 6 to 78 ± 1° full width at half-maximum (FWHM)) and the collagen III/I ratio (0.02 to 0.42). Principal component analysis (PCA) comparing the physical properties of the modifiers (e.g. hydrophobicity, molar volume, freely rotating bonds, polarizability) with the SHG analytically derived parameters (e.g. collagen III/I ratio, collagen orientation) was performed. Chemical properties of the PLR-like modifications including lipophilicity, along with the number of freely rotating bonds and the polar izability had significant effects on the collagen surrounding the implant, both in terms of collagen orientation as well as the production of collagen III. These findings demonstrate the possibility of tuning the foreign body response, in terms of collagen deposition and organization, to positively influence the acceptance of implanted biomaterials

Biocompatible scaffolds based on natural polymers for regenerative medicine

The chitosan and gelatine are commonly used biopolymers for the tissue engineering applications. In the previous methods for the cryogels synthesis, multistep preparation methods using toxic cross-linking agents such as glutaraldehyde are reported. Here, we present a two-step preparation method of gelatin macroporous cryogels and one-step preparation method of chitosan or gelatin cryogels. The physico-chemical properties of obtained scaffolds were characterized using FTIR, zeta potential, SEM and laser confocal microscopy. Non-toxic and biodegradable cross-linking agents such as oxidized dextran and 1,1,3,3-tetramethoxypropane are utilized. The one-step chitosan cryogels had degradation degree ~2 times higher compared to the cryogels prepared with a two-step method i.e. reduced by borohydride. Scaffolds cross-linked by glutaraldehyde had about 40% viability, whereas nine various compositions of cryogels showed significantly higher viability (~80%) of fibroblast cells in vitro. The cryogels were obtained without using the harmful compounds and therefore can be used straightforward as biocompatible and biodegradable scaffolds for the cell culturing purposes and other biomedical applications

Quantitative Characterization of Collagen in the Fibrotic Capsule Surrounding Implanted Polymeric Microparticles through Second Harmonic Generation Imaging

The collagenous capsule formed around an implant will ultimately determine the nature of its in vivo fate. To provide a better understanding of how surface modifications can alter the collagen orientation and composition in the fibrotic capsule, we used second harmonic generation (SHG) microscopy to evaluate collagen organization and structure generated in mice subcutaneously injected with chemically functionalized polystyrene particles. SHG is sensitive to the orientation of a molecule, making it a powerful tool for measuring the alignment of collagen fibers. Additionally, SHG arises from the second order susceptibility of the interrogated molecule in response to the electric field. Variation in these tensor components distinguishes different molecular sources of SHG, providing collagen type specificity. Here, we demonstrated the ability of SHG to differentiate collagen type I and type III quantitatively and used this method to examine fibrous capsules of implanted polystyrene particles. Data presented in this work shows a wide range of collagen fiber orientations and collagen compositions in response to surface functionalized polystyrene particles. Dimethylamino functionalized particles were able to form a thin collagenous matrix resembling healthy skin. These findings have the potential to improve the fundamental understanding of how material properties influence collagen organization and composition quantitatively.This article is published as Akilbekova, Dana, and Kaitlin M. Bratlie. "Quantitative characterization of collagen in the fibrotic capsule surrounding implanted polymeric microparticles through second harmonic generation imaging." PLOS ONE 10, no. 6 (2015): e0130386, DOI: 10.1371/journal.pone.0130386. Posted with permission.</p

A) Histograms of χzzzχzxx values obtained for gels with varying collagen type III concentration.

<p>The bars represent experimentally acquired data. The red line is the bimodal Gaussian fit to the data. B) Standard curve for collagen type III concentration. The known concentration of collagen concentration is plotted against the ratio of the area under the collagen type III peak ~0.8 to the total area under the Gaussian fit.</p