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An in vitro assay of collagen fiber alignment by acupuncture needle rotation.

Julias M, Edgar LT, Buettner HM, Shreiber DI - Biomed Eng Online (2008)

Bottom Line: Crosslinked collagen failed at a significantly lower number of revolutions than untreated collagen, whereas collagen concentration had no effect on gel failure.The strength of the alignment field increased with increasing collagen concentration and decreased with crosslinking.For the same depth of insertion, alignment was greater in thinner gels.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA. tikus@eden.rutgers.edu

ABSTRACT

Background: During traditional acupuncture therapy, soft tissues attach to and wind around the acupuncture needle. To study this phenomenon in a controlled and quantitative setting, we performed acupuncture needling in vitro.

Methods: Acupuncture was simulated in vitro in three-dimensional, type I collagen gels prepared at 1.5 mg/ml, 2.0 mg/ml, and 2.5 mg/ml collagen, and either crosslinked with formalin or left untreated. Acupuncture needles were inserted into the gels and rotated via a computer-controlled motor at 0.3 rev/sec for up to 10 revolutions while capturing the evolution of birefringence under cross-polarization.

Results: Simulated acupuncture produced circumferential alignment of collagen fibers close to the needle that evolved into radial alignment as the distance from the needle increased, which generally matched observations from published tissue explant studies. All gels failed prior to 10 revolutions, and the location of failure was near the transition between circumferential and radial alignment. Crosslinked collagen failed at a significantly lower number of revolutions than untreated collagen, whereas collagen concentration had no effect on gel failure. The strength of the alignment field increased with increasing collagen concentration and decreased with crosslinking. Separate studies were performed in which the gel thickness and depth of needle insertion were varied. As gel thickness increased, gels failed at fewer needle revolutions. For the same depth of insertion, alignment was greater in thinner gels. Alignment increased as the depth of insertion increased.

Conclusion: These results indicate that the mechanostructural properties of soft connective tissues may affect their response to acupuncture therapy. The in vitro model provides a platform to study mechanotransduction during acupuncture in a highly controlled and quantitative setting.

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Related in: MedlinePlus

Schematic of polarized light microscopy system. A dissection stereomicroscope with a USB camera was mounted upside-down to a bench top. A fiber-optic ring light was attached to the motor housing providing a light source to the sample without hindrance from the motor. The polarizer was placed on top of the sample dish, and the analyzer was placed on the microscope as shown with the axis of polarization orthogonal to the axis for the polarizer. A small hole in the polarizer allowed free insertion and rotation of the acupuncture needle in the sample.
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Figure 1: Schematic of polarized light microscopy system. A dissection stereomicroscope with a USB camera was mounted upside-down to a bench top. A fiber-optic ring light was attached to the motor housing providing a light source to the sample without hindrance from the motor. The polarizer was placed on top of the sample dish, and the analyzer was placed on the microscope as shown with the axis of polarization orthogonal to the axis for the polarizer. A small hole in the polarizer allowed free insertion and rotation of the acupuncture needle in the sample.

Mentions: Polarization light microscopy (PLM) was used to observe and image the evolution of fiber alignment continuously in real time. A dissection stereomicroscope (Carl Zeiss Microimaging, Thornwood, NY) with a USB camera (Matrix Vision, GmbH, Oppenweiler, Germany) was physically inverted and clamped to a benchtop, such that the base of the microscope provided a platform to hold the motor stand and MatTek dish (Figure 1). A fiber-optic ring light (Edmund Optics, Barrington, NJ) was attached to the motor housing. The gel was placed between two polarizers, which were positioned as 'cross-polars' with their respective angles of polarization 90° apart. In this arrangement, as the light passes through the filter-sample-filter optic train, the darkest area of the resulting image occurs where collagen fibers are oriented parallel or perpendicular to the optical axis of either polarizing element; the brightest area occurs where collagen fibers are oriented 45° to the filter optical axis. The collagen gel was needled for 10 revolutions. Images were captured at 6 frames per second during needle rotation and were analyzed with MATLAB (The Mathworks, Inc, Natick, MA), as described below. Six experiments, each comprising three replicates, were performed for untreated collagen gels, and five experiments were performed for crosslinked gels, also in triplicate.


An in vitro assay of collagen fiber alignment by acupuncture needle rotation.

Julias M, Edgar LT, Buettner HM, Shreiber DI - Biomed Eng Online (2008)

Schematic of polarized light microscopy system. A dissection stereomicroscope with a USB camera was mounted upside-down to a bench top. A fiber-optic ring light was attached to the motor housing providing a light source to the sample without hindrance from the motor. The polarizer was placed on top of the sample dish, and the analyzer was placed on the microscope as shown with the axis of polarization orthogonal to the axis for the polarizer. A small hole in the polarizer allowed free insertion and rotation of the acupuncture needle in the sample.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2483714&req=5

Figure 1: Schematic of polarized light microscopy system. A dissection stereomicroscope with a USB camera was mounted upside-down to a bench top. A fiber-optic ring light was attached to the motor housing providing a light source to the sample without hindrance from the motor. The polarizer was placed on top of the sample dish, and the analyzer was placed on the microscope as shown with the axis of polarization orthogonal to the axis for the polarizer. A small hole in the polarizer allowed free insertion and rotation of the acupuncture needle in the sample.
Mentions: Polarization light microscopy (PLM) was used to observe and image the evolution of fiber alignment continuously in real time. A dissection stereomicroscope (Carl Zeiss Microimaging, Thornwood, NY) with a USB camera (Matrix Vision, GmbH, Oppenweiler, Germany) was physically inverted and clamped to a benchtop, such that the base of the microscope provided a platform to hold the motor stand and MatTek dish (Figure 1). A fiber-optic ring light (Edmund Optics, Barrington, NJ) was attached to the motor housing. The gel was placed between two polarizers, which were positioned as 'cross-polars' with their respective angles of polarization 90° apart. In this arrangement, as the light passes through the filter-sample-filter optic train, the darkest area of the resulting image occurs where collagen fibers are oriented parallel or perpendicular to the optical axis of either polarizing element; the brightest area occurs where collagen fibers are oriented 45° to the filter optical axis. The collagen gel was needled for 10 revolutions. Images were captured at 6 frames per second during needle rotation and were analyzed with MATLAB (The Mathworks, Inc, Natick, MA), as described below. Six experiments, each comprising three replicates, were performed for untreated collagen gels, and five experiments were performed for crosslinked gels, also in triplicate.

Bottom Line: Crosslinked collagen failed at a significantly lower number of revolutions than untreated collagen, whereas collagen concentration had no effect on gel failure.The strength of the alignment field increased with increasing collagen concentration and decreased with crosslinking.For the same depth of insertion, alignment was greater in thinner gels.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA. tikus@eden.rutgers.edu

ABSTRACT

Background: During traditional acupuncture therapy, soft tissues attach to and wind around the acupuncture needle. To study this phenomenon in a controlled and quantitative setting, we performed acupuncture needling in vitro.

Methods: Acupuncture was simulated in vitro in three-dimensional, type I collagen gels prepared at 1.5 mg/ml, 2.0 mg/ml, and 2.5 mg/ml collagen, and either crosslinked with formalin or left untreated. Acupuncture needles were inserted into the gels and rotated via a computer-controlled motor at 0.3 rev/sec for up to 10 revolutions while capturing the evolution of birefringence under cross-polarization.

Results: Simulated acupuncture produced circumferential alignment of collagen fibers close to the needle that evolved into radial alignment as the distance from the needle increased, which generally matched observations from published tissue explant studies. All gels failed prior to 10 revolutions, and the location of failure was near the transition between circumferential and radial alignment. Crosslinked collagen failed at a significantly lower number of revolutions than untreated collagen, whereas collagen concentration had no effect on gel failure. The strength of the alignment field increased with increasing collagen concentration and decreased with crosslinking. Separate studies were performed in which the gel thickness and depth of needle insertion were varied. As gel thickness increased, gels failed at fewer needle revolutions. For the same depth of insertion, alignment was greater in thinner gels. Alignment increased as the depth of insertion increased.

Conclusion: These results indicate that the mechanostructural properties of soft connective tissues may affect their response to acupuncture therapy. The in vitro model provides a platform to study mechanotransduction during acupuncture in a highly controlled and quantitative setting.

Show MeSH
Related in: MedlinePlus