Imaging challenges in biomaterials and tissue engineering.
TL;DR: This review focuses on evaluating the application of available imaging modalities for assessment of biomaterials and tissue in TERM applications and a discussion of limitations of these techniques and identification of areas for further development.
About: This article is published in Biomaterials.The article was published on 2013-09-01 and is currently open access. It has received 235 citations till now.
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TL;DR: Developments in fabricating sophisticated grafts and tissue mimics and technologies for integrating grafts with host vasculature will be discussed, and directions for current and future regenerative medicine therapies are proposed.
Abstract: Organ and tissue loss through disease and injury motivate the development of therapies that can regenerate tissues and decrease reliance on transplantations. Regenerative medicine, an interdisciplinary field that applies engineering and life science principles to promote regeneration, can potentially restore diseased and injured tissues and whole organs. Since the inception of the field several decades ago, a number of regenerative medicine therapies, including those designed for wound healing and orthopedics applications, have received Food and Drug Administration (FDA) approval and are now commercially available. These therapies and other regenerative medicine approaches currently being studied in preclinical and clinical settings will be covered in this review. Specifically, developments in fabricating sophisticated grafts and tissue mimics and technologies for integrating grafts with host vasculature will be discussed. Enhancing the intrinsic regenerative capacity of the host by altering its environment, whether with cell injections or immune modulation, will be addressed, as well as methods for exploiting recently developed cell sources. Finally, we propose directions for current and future regenerative medicine therapies.
592 citations
TL;DR: The rGO-AuNRVe-DOX capable of sequential DOX release by laser light and acid environment may have the potential for clinical translation to treat cancer patients with tumors accessible by light.
Abstract: We report a hybrid reduced graphene oxide (rGO)-loaded ultrasmall plasmonic gold nanorod vesicle (rGO-AuNRVe) (∼65 nm in size) with remarkably amplified photoacoustic (PA) performance and photothermal effects. The hybrid vesicle also exhibits a high loading capacity of doxorubicin (DOX), as both the cavity of the vesicle and the large surface area of the encapsulated rGO can be used for loading DOX, making it an excellent drug carrier. The loaded DOX is released sequentially: near-infrared photothermal heating induces DOX release from the vesicular cavity, and an intracellular acidic environment induces DOX release from the rGO surface. Positron emission tomography imaging showed high passive U87MG tumor accumulation of 64Cu-labeled rGO-AuNRVes (∼9.7% ID/g at 24 h postinjection) and strong PA signal in the tumor region. Single intravenous injection of rGO-AuNRVe-DOX followed by low-power-density 808 nm laser irradiation (0.25 W/cm2) revealed effective inhibition of tumor growth due to the combination of c...
311 citations
TL;DR: Several challenges must be overcome in the application of 3D bioprinting before this disruptive technology is widely used to create organotypic constructs for regenerative medicine.
Abstract: Humans and animals lose tissues and organs due to congenital defects, trauma, and diseases. The human body has a low regenerative potential as opposed to the urodele amphibians commonly referred to as salamanders. Globally, millions of people would benefit immensely if tissues and organs can be replaced on demand. Traditionally, transplantation of intact tissues and organs has been the bedrock to replace damaged and diseased parts of the body. The sole reliance on transplantation has created a waiting list of people requiring donated tissues and organs, and generally, supply cannot meet the demand. The total cost to society in terms of caring for patients with failing organs and debilitating diseases is enormous. Scientists and clinicians, motivated by the need to develop safe and reliable sources of tissues and organs, have been improving therapies and technologies that can regenerate tissues and in some cases create new tissues altogether. Tissue engineering and/or regenerative medicine are fields of life science employing both engineering and biological principles to create new tissues and organs and to promote the regeneration of damaged or diseased tissues and organs. Major advances and innovations are being made in the fields of tissue engineering and regenerative medicine and have a huge impact on three-dimensional bioprinting (3D bioprinting) of tissues and organs. 3D bioprinting holds great promise for artificial tissue and organ bioprinting, thereby revolutionizing the field of regenerative medicine. This review discusses how recent advances in the field of regenerative medicine and tissue engineering can improve 3D bioprinting and vice versa. Several challenges must be overcome in the application of 3D bioprinting before this disruptive technology is widely used to create organotypic constructs for regenerative medicine.
236 citations
TL;DR: Progress is described in designing stimuli-responsive, optically transparent hydrogels that can be used as biomimetic extracellular matrices (ECMs) to study cell differentiation and migration in the context of modeling the nervous system and cancer.
Abstract: ConspectusConventional cell culture techniques using 2D polystyrene or glass have provided great insight into key biochemical mechanisms responsible for cellular events such as cell proliferation, differentiation, and cell–cell interactions. However, the physical and chemical properties of 2D culture in vitro are dramatically different than those found in the native cellular microenvironment in vivo. Cells grown on 2D substrates differ significantly from those grown in vivo, and this explains, in part, why many promising drug candidates discovered through in vitro drug screening assays fail when they are translated to in vivo animal or human models. To overcome this obstacle, 3D cell culture using biomimetic hydrogels has emerged as an alternative strategy to recapitulate native cell growth in vitro.Hydrogels, which are water-swollen polymers, can be synthetic or naturally derived. Many methods have been developed to control the physical and chemical properties of the hydrogels to match those found in spe...
131 citations
TL;DR: Commonly used biomedical imaging modalities, including X-ray and computed tomography, positron emission tomography and single photon emission computed tomographic, magnetic resonance imaging, ultrasound imaging, optical imaging, and emerging techniques and multimodal imaging, will be discussed, focusing on the latest trends of their applications in recent tissue engineering studies.
Abstract: Tissue engineering has evolved with multifaceted research being conducted using advanced technologies, and it is progressing toward clinical applications. As tissue engineering technology significantly advances, it proceeds toward increasing sophistication, including nanoscale strategies for material construction and synergetic methods for combining with cells, growth factors, or other macromolecules. Therefore, to assess advanced tissue-engineered constructs, tissue engineers need versatile imaging methods capable of monitoring not only morphological but also functional and molecular information. However, there is no single imaging modality that is suitable for all tissue-engineered constructs. Each imaging method has its own range of applications and provides information based on the specific properties of the imaging technique. Therefore, according to the requirements of the tissue engineering studies, the most appropriate tool should be selected among a variety of imaging modalities. The goal of this review article is to describe available biomedical imaging methods to assess tissue engineering applications and to provide tissue engineers with criteria and insights for determining the best imaging strategies. Commonly used biomedical imaging modalities, including X-ray and computed tomography, positron emission tomography and single photon emission computed tomography, magnetic resonance imaging, ultrasound imaging, optical imaging, and emerging techniques and multimodal imaging, will be discussed, focusing on the latest trends of their applications in recent tissue engineering studies.
123 citations
Cites background or methods from "Imaging challenges in biomaterials ..."
...Numerous tissue engineering studies still utilize conventional tools, such as histological techniques, which provide important but limited information, especially in the case of in vivo preclinical and clinical approaches.(4) Visualizing tissue-engineered constructs using these conventional methods requires destruction of the samples, meaning that longitudinal three-dimensional (3D) volumetric assessment is extremely limited....
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...PET/CT or SPECT/CT can be effectively coupled with many shared components, and it can be highly useful for tissue engineering applications because PET and SPECT can provide functional information concerning cellular and tissue function and CT provides structural information about the surrounding tissue.(4,123) For instance, in vivo molecular imaging was performed with PET/CT to observe matrix metalloproteinase increase (PET) and corresponding bone formation changes (CT) at different time points after BMPinduced cell injection....
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References
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TL;DR: A review of the state of the art of photoacoustic tomography for both biological and clinical studies can be found in this paper, where the authors discuss the current state-of-the-art and discuss future prospects.
Abstract: Photoacoustic tomography (PAT) can create multiscale multicontrast images of living biological structures ranging from organelles to organs. This emerging technology overcomes the high degree of scattering of optical photons in biological tissue by making use of the photoacoustic effect. Light absorption by molecules creates a thermally induced pressure jump that launches ultrasonic waves, which are received by acoustic detectors to form images. Different implementations of PAT allow the spatial resolution to be scaled with the desired imaging depth in tissue while a high depth-to-resolution ratio is maintained. As a rule of thumb, the achievable spatial resolution is on the order of 1/200 of the desired imaging depth, which can reach up to 7 centimeters. PAT provides anatomical, functional, metabolic, molecular, and genetic contrasts of vasculature, hemodynamics, oxygen metabolism, biomarkers, and gene expression. We review the state of the art of PAT for both biological and clinical studies and discuss future prospects.
3,518 citations
"Imaging challenges in biomaterials ..." refers background in this paper
...Photoacoustic microscopy (PAM) is a rapidly emerging hybrid modality that combines optical image contrast with US detection principles [76]....
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TL;DR: Optical coherence tomography functions as a type of 'optical biopsy' to provide cross-sectional images of tissue structure on the micron scale and is a promising imaging technology because it can provide images of tissues in situ and in real time, without the need for excision and processing of specimens.
Abstract: Optical coherence tomography (OCT) is an emerging biomedical optical imaging technique that performs high-resolution, cross-sectional tomographic imaging of microstructure in biological systems. OCT can achieve image resolutions of 1-15 microm, one to two orders of magnitude finer than standard ultrasound. The image penetration depth of OCT is determined by the optical scattering and is up to 2-3 mm in tissue. OCT functions as a type of 'optical biopsy' to provide cross-sectional images of tissue structure on the micron scale. It is a promising imaging technology because it can provide images of tissue in situ and in real time, without the need for excision and processing of specimens.
1,031 citations
"Imaging challenges in biomaterials ..." refers background in this paper
...OCT can image samples up to 2e3mm thick but spatial resolution diminishes from 1 to 15 microns as depth increases [25,45]....
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TL;DR: In this paper, the authors measured the hardness of pseudoelastic NiTi shape memory alloys (SMAs) during the solid-state phase transition in NiTi SMAs.
Abstract: Due to a distinct nature of thermomechanical smart materials' reaction to applied loads, a revolutionary approach is needed to measure the hardness and to understand its size effect for pseudoelastic NiTi shape memory alloys (SMAs) during the solid-state phase transition. Spherical hardness is increased with depths during the phase transition in NiTi SMAs. This behaviour is contrary to the decrease in the hardness of NiTi SMAs with depths using sharp tips and the depth-insensitive hardness of traditional metallic alloys using spherical tips. In contrast with the common dislocation theory for the hardness measurement, the nature of NiTi SMAs' hardness is explained by the balance between the interface and the bulk energy of phase transformed SMAs. Contrary to the energy balance in the indentation zone using sharp tips, the interface energy was numerically shown to be less dominant than the bulk energy of the phase transition zone using spherical tips.
607 citations
TL;DR: The results indicate that delivery of both growth factors may enhance bone bridging and union of the critical size defect compared to delivery of BMP-2 alone and suggests an interplay between these growth factors for early bone regeneration.
545 citations
TL;DR: Micro CT is a more recent method of examining the characteristics of scaffolds and this review aims to highlight this current approach while comparing it with other techniques.
488 citations