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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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Frequency sweep of collagen gels under 1% controlled strain (average +/- standard error). (A) Storage Modulus; (B) Loss Modulus. Both the storage and loss moduli demonstrated significant increases with increasing collagen concentration and crosslinking (2-way ANOVA, P < 0.001). Key: c: crosslinked, u: untreated.
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Figure 11: Frequency sweep of collagen gels under 1% controlled strain (average +/- standard error). (A) Storage Modulus; (B) Loss Modulus. Both the storage and loss moduli demonstrated significant increases with increasing collagen concentration and crosslinking (2-way ANOVA, P < 0.001). Key: c: crosslinked, u: untreated.

Mentions: Storage and loss moduli were determined using parallel plate rheometry. The storage modulus showed a gradual increase with increasing frequency, before sharply dropping (Figure 11A). Inspection of gels revealed damage to the samples, which did not occur if experiments were run only at lower frequencies (data not shown), and we assumed that the damage was responsible for the apparent decrease in stiffness. In general, increased collagen concentration and crosslinking delayed this damage. The loss modulus for untreated gels showed a gradual increase at low frequencies, particularly for untreated collagen (Figure 11B). The loss modulus for crosslinked collagen decreased at moderate frequencies, and increased more sharply for all cases concurrent with the decrease in storage modulus. Two-way ANOVA revealed significant increases in the storage and loss moduli at all frequencies with increasing collagen concentration and crosslinking (all P < 0.001).


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

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

Frequency sweep of collagen gels under 1% controlled strain (average +/- standard error). (A) Storage Modulus; (B) Loss Modulus. Both the storage and loss moduli demonstrated significant increases with increasing collagen concentration and crosslinking (2-way ANOVA, P < 0.001). Key: c: crosslinked, u: untreated.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 11: Frequency sweep of collagen gels under 1% controlled strain (average +/- standard error). (A) Storage Modulus; (B) Loss Modulus. Both the storage and loss moduli demonstrated significant increases with increasing collagen concentration and crosslinking (2-way ANOVA, P < 0.001). Key: c: crosslinked, u: untreated.
Mentions: Storage and loss moduli were determined using parallel plate rheometry. The storage modulus showed a gradual increase with increasing frequency, before sharply dropping (Figure 11A). Inspection of gels revealed damage to the samples, which did not occur if experiments were run only at lower frequencies (data not shown), and we assumed that the damage was responsible for the apparent decrease in stiffness. In general, increased collagen concentration and crosslinking delayed this damage. The loss modulus for untreated gels showed a gradual increase at low frequencies, particularly for untreated collagen (Figure 11B). The loss modulus for crosslinked collagen decreased at moderate frequencies, and increased more sharply for all cases concurrent with the decrease in storage modulus. Two-way ANOVA revealed significant increases in the storage and loss moduli at all frequencies with increasing collagen concentration and crosslinking (all P < 0.001).

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