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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

Polarized light images of collagen gel response to in vitro acupuncture after 2 needle revolutions (A-C), and 4 revolutions (D-F) in untreated collagen gels and 2 revolutions (G-I) in crosslinked gels. The birefringent area increased with increasing revolutions, and was greater in untreated collagen compared to crosslinked collagen at the same number of revolutions. This area also increased with increasing collagen concentration for each condition (A, D, G – 1.5 mg/ml; B, E, H – 2.0 mg/ml; C, F, I – 2.5 mg/ml). Bar = 1 mm.
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Figure 6: Polarized light images of collagen gel response to in vitro acupuncture after 2 needle revolutions (A-C), and 4 revolutions (D-F) in untreated collagen gels and 2 revolutions (G-I) in crosslinked gels. The birefringent area increased with increasing revolutions, and was greater in untreated collagen compared to crosslinked collagen at the same number of revolutions. This area also increased with increasing collagen concentration for each condition (A, D, G – 1.5 mg/ml; B, E, H – 2.0 mg/ml; C, F, I – 2.5 mg/ml). Bar = 1 mm.

Mentions: The alignment pattern observed with confocal microscopy was evident in PLM images as a clover-leaf pattern of birefringence, where fiber alignment 45° off-axis generates an intensity peak. The area of alignment at the same number of revolutions was visually greater with increasing collagen concentration and in untreated collagen gels vs. crosslinked gels (up to 2 revolutions) (Figure 6). A continuous index of the area of alignment was generated by binarizing the complete set of images in each run using a threshold intensity as described above. For untreated collagen gels, the average area of alignment increased more rapidly and to a higher final value with increasing concentration (Figure 7). Crosslinked samples aligned more gradually than untreated gels (Figure 8), and also demonstrated the trend of increased area of alignment with increasing collagen concentration.


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

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

Polarized light images of collagen gel response to in vitro acupuncture after 2 needle revolutions (A-C), and 4 revolutions (D-F) in untreated collagen gels and 2 revolutions (G-I) in crosslinked gels. The birefringent area increased with increasing revolutions, and was greater in untreated collagen compared to crosslinked collagen at the same number of revolutions. This area also increased with increasing collagen concentration for each condition (A, D, G – 1.5 mg/ml; B, E, H – 2.0 mg/ml; C, F, I – 2.5 mg/ml). Bar = 1 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Polarized light images of collagen gel response to in vitro acupuncture after 2 needle revolutions (A-C), and 4 revolutions (D-F) in untreated collagen gels and 2 revolutions (G-I) in crosslinked gels. The birefringent area increased with increasing revolutions, and was greater in untreated collagen compared to crosslinked collagen at the same number of revolutions. This area also increased with increasing collagen concentration for each condition (A, D, G – 1.5 mg/ml; B, E, H – 2.0 mg/ml; C, F, I – 2.5 mg/ml). Bar = 1 mm.
Mentions: The alignment pattern observed with confocal microscopy was evident in PLM images as a clover-leaf pattern of birefringence, where fiber alignment 45° off-axis generates an intensity peak. The area of alignment at the same number of revolutions was visually greater with increasing collagen concentration and in untreated collagen gels vs. crosslinked gels (up to 2 revolutions) (Figure 6). A continuous index of the area of alignment was generated by binarizing the complete set of images in each run using a threshold intensity as described above. For untreated collagen gels, the average area of alignment increased more rapidly and to a higher final value with increasing concentration (Figure 7). Crosslinked samples aligned more gradually than untreated gels (Figure 8), and also demonstrated the trend of increased area of alignment with increasing collagen concentration.

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