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In vitro methods for evaluating therapeutic ultrasound exposures: present-day models and future innovations.

Alassaf A, Aleid A, Frenkel V - J Ther Ultrasound (2013)

Bottom Line: Each of these methods possesses characteristics that are well suited for various well-defined investigative goals.None, however, incorporate all the properties of real tissues, which include a 3D environment and live cells that may be maintained long-term post-treatment.Additional reporting is presented on the exciting and emerging field of 3D biological scaffolds, employing methods and materials adapted from tissue engineering.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Catholic University of America, 620 Michigan Ave NE, Washington, DC 20064, USA.

ABSTRACT
Although preclinical experiments are ultimately required to evaluate new therapeutic ultrasound exposures and devices prior to clinical trials, in vitro experiments can play an important role in the developmental process. A variety of in vitro methods have been developed, where each of these has demonstrated their utility for various test purposes. These include inert tissue-mimicking phantoms, which can incorporate thermocouples or cells and ex vivo tissue. Cell-based methods have also been used, both in monolayer and suspension. More biologically relevant platforms have also shown utility, such as blood clots and collagen gels. Each of these methods possesses characteristics that are well suited for various well-defined investigative goals. None, however, incorporate all the properties of real tissues, which include a 3D environment and live cells that may be maintained long-term post-treatment. This review is intended to provide an overview of the existing application-specific in vitro methods available to therapeutic ultrasound investigators, highlighting their advantages and limitations. Additional reporting is presented on the exciting and emerging field of 3D biological scaffolds, employing methods and materials adapted from tissue engineering. This type of platform holds much promise for achieving more representative conditions of those found in vivo, especially important for the newest sphere of therapeutic applications, based on molecular changes that may be generated in response to non-destructive exposures.

No MeSH data available.


Related in: MedlinePlus

Chitosan-gelatin biological scaffolds. (left) 2D scaffold: (a) brightfield image showing the fibrous structure of the scaffold; (b) fluorescent image of the same scaffold in (a), where the nuclei of fibroblasts are visible, stained with DAPI. Bar = 100 μm. (right) 3D scaffolds sectioned, stained with Masson's trichrome (red, scaffold; purple, fibroblasts), and observed with brightfield microscopy. (c) Edge region of a non-cellularized scaffold (bar = 200 μm). (inset) Entire scaffold (height = 7 mm; radius = 20 mm). (d,e) Regions of cellularized scaffolds (outer surface at top) (bar = 50 μm). Pore sizes range from 50 to 200 μm, with various degrees of cellularization.
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Figure 5: Chitosan-gelatin biological scaffolds. (left) 2D scaffold: (a) brightfield image showing the fibrous structure of the scaffold; (b) fluorescent image of the same scaffold in (a), where the nuclei of fibroblasts are visible, stained with DAPI. Bar = 100 μm. (right) 3D scaffolds sectioned, stained with Masson's trichrome (red, scaffold; purple, fibroblasts), and observed with brightfield microscopy. (c) Edge region of a non-cellularized scaffold (bar = 200 μm). (inset) Entire scaffold (height = 7 mm; radius = 20 mm). (d,e) Regions of cellularized scaffolds (outer surface at top) (bar = 50 μm). Pore sizes range from 50 to 200 μm, with various degrees of cellularization.

Mentions: One of the exciting possibilities that we have begun investigating is the use of 2D scaffolds 'rolled up’ in to pseudo-blood vessels that would then be embedded in an inert gel phantom, which would provide structural support for the vessel. A blood-mimicking fluid [56] could then be circulated through the vessel while ultrasound exposures are being carried out. Such a setup would allow investigations of ultrasound-mediated drug delivery applications. This includes sonoporation [57], and also the deployment of drugs from temperature sensitive liposomes [58]. Examples of both 2D and 3D biological scaffolds that we have been preparing appear in Figure 5.


In vitro methods for evaluating therapeutic ultrasound exposures: present-day models and future innovations.

Alassaf A, Aleid A, Frenkel V - J Ther Ultrasound (2013)

Chitosan-gelatin biological scaffolds. (left) 2D scaffold: (a) brightfield image showing the fibrous structure of the scaffold; (b) fluorescent image of the same scaffold in (a), where the nuclei of fibroblasts are visible, stained with DAPI. Bar = 100 μm. (right) 3D scaffolds sectioned, stained with Masson's trichrome (red, scaffold; purple, fibroblasts), and observed with brightfield microscopy. (c) Edge region of a non-cellularized scaffold (bar = 200 μm). (inset) Entire scaffold (height = 7 mm; radius = 20 mm). (d,e) Regions of cellularized scaffolds (outer surface at top) (bar = 50 μm). Pore sizes range from 50 to 200 μm, with various degrees of cellularization.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109267&req=5

Figure 5: Chitosan-gelatin biological scaffolds. (left) 2D scaffold: (a) brightfield image showing the fibrous structure of the scaffold; (b) fluorescent image of the same scaffold in (a), where the nuclei of fibroblasts are visible, stained with DAPI. Bar = 100 μm. (right) 3D scaffolds sectioned, stained with Masson's trichrome (red, scaffold; purple, fibroblasts), and observed with brightfield microscopy. (c) Edge region of a non-cellularized scaffold (bar = 200 μm). (inset) Entire scaffold (height = 7 mm; radius = 20 mm). (d,e) Regions of cellularized scaffolds (outer surface at top) (bar = 50 μm). Pore sizes range from 50 to 200 μm, with various degrees of cellularization.
Mentions: One of the exciting possibilities that we have begun investigating is the use of 2D scaffolds 'rolled up’ in to pseudo-blood vessels that would then be embedded in an inert gel phantom, which would provide structural support for the vessel. A blood-mimicking fluid [56] could then be circulated through the vessel while ultrasound exposures are being carried out. Such a setup would allow investigations of ultrasound-mediated drug delivery applications. This includes sonoporation [57], and also the deployment of drugs from temperature sensitive liposomes [58]. Examples of both 2D and 3D biological scaffolds that we have been preparing appear in Figure 5.

Bottom Line: Each of these methods possesses characteristics that are well suited for various well-defined investigative goals.None, however, incorporate all the properties of real tissues, which include a 3D environment and live cells that may be maintained long-term post-treatment.Additional reporting is presented on the exciting and emerging field of 3D biological scaffolds, employing methods and materials adapted from tissue engineering.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Catholic University of America, 620 Michigan Ave NE, Washington, DC 20064, USA.

ABSTRACT
Although preclinical experiments are ultimately required to evaluate new therapeutic ultrasound exposures and devices prior to clinical trials, in vitro experiments can play an important role in the developmental process. A variety of in vitro methods have been developed, where each of these has demonstrated their utility for various test purposes. These include inert tissue-mimicking phantoms, which can incorporate thermocouples or cells and ex vivo tissue. Cell-based methods have also been used, both in monolayer and suspension. More biologically relevant platforms have also shown utility, such as blood clots and collagen gels. Each of these methods possesses characteristics that are well suited for various well-defined investigative goals. None, however, incorporate all the properties of real tissues, which include a 3D environment and live cells that may be maintained long-term post-treatment. This review is intended to provide an overview of the existing application-specific in vitro methods available to therapeutic ultrasound investigators, highlighting their advantages and limitations. Additional reporting is presented on the exciting and emerging field of 3D biological scaffolds, employing methods and materials adapted from tissue engineering. This type of platform holds much promise for achieving more representative conditions of those found in vivo, especially important for the newest sphere of therapeutic applications, based on molecular changes that may be generated in response to non-destructive exposures.

No MeSH data available.


Related in: MedlinePlus