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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

Effects of gel height and depth of needle insertion on revolutions to failure during in vitro acupuncture. Thin gels were able to withstand significantly more needling than thick ones (P < 0.001). For 4 mm-thick gels, revolutions to failure decreased as the depth of needle insertion increased, but this was not observed for 6 mm-thick gels.
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Figure 9: Effects of gel height and depth of needle insertion on revolutions to failure during in vitro acupuncture. Thin gels were able to withstand significantly more needling than thick ones (P < 0.001). For 4 mm-thick gels, revolutions to failure decreased as the depth of needle insertion increased, but this was not observed for 6 mm-thick gels.

Mentions: The depth of insertion study was performed with a new shipment of collagen, and preliminary experiments with collagen from the crosslinking and collagen concentration studies indicated that the new batch presented significantly less alignment than the old batch, but that trends in the response were the same. As such, experiments in the depth of insertion studies were performed exclusively with the new batch of collagen and analyzed separately from the crosslinking and collagen concentration studies. Changing the depth of needle insertion significantly affected the failure of the gels (Figure 9). Thicker gels failed at fewer revolutions than thinner gels. For 4 mm-thick gels, increasing the depth/percentage of needle insertion decreased the revolutions before failure, but this was not observed consistently with the 6 mm-thick gels. The alignment of gels was also affected by insertion depth and percentage (Figure 10). In vitro acupuncture with needles inserted the same depth in gels of different thickness generated more alignment in thinner gels, indicating that the fraction of the gel that is subjected to needle rotation is an important parameter in dictating the response. Maintaining the same percentage of insertion at gels of different thickness produced greater alignment in thicker gels than thinner gels. For example, inserting a needle 3 mm into a 4 mm-thick gel and rotating the needle produced more alignment than the same procedure in a 6 mm-thick gel (inverted triangles, Figure 10A and 10B). However, inserting a needle 75% into a 6 mm-thick gel (squares, Figure 10B) produces more alignment than 75% into a 4 mm gel (inverted triangles, Figure 10A).


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

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

Effects of gel height and depth of needle insertion on revolutions to failure during in vitro acupuncture. Thin gels were able to withstand significantly more needling than thick ones (P < 0.001). For 4 mm-thick gels, revolutions to failure decreased as the depth of needle insertion increased, but this was not observed for 6 mm-thick gels.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 9: Effects of gel height and depth of needle insertion on revolutions to failure during in vitro acupuncture. Thin gels were able to withstand significantly more needling than thick ones (P < 0.001). For 4 mm-thick gels, revolutions to failure decreased as the depth of needle insertion increased, but this was not observed for 6 mm-thick gels.
Mentions: The depth of insertion study was performed with a new shipment of collagen, and preliminary experiments with collagen from the crosslinking and collagen concentration studies indicated that the new batch presented significantly less alignment than the old batch, but that trends in the response were the same. As such, experiments in the depth of insertion studies were performed exclusively with the new batch of collagen and analyzed separately from the crosslinking and collagen concentration studies. Changing the depth of needle insertion significantly affected the failure of the gels (Figure 9). Thicker gels failed at fewer revolutions than thinner gels. For 4 mm-thick gels, increasing the depth/percentage of needle insertion decreased the revolutions before failure, but this was not observed consistently with the 6 mm-thick gels. The alignment of gels was also affected by insertion depth and percentage (Figure 10). In vitro acupuncture with needles inserted the same depth in gels of different thickness generated more alignment in thinner gels, indicating that the fraction of the gel that is subjected to needle rotation is an important parameter in dictating the response. Maintaining the same percentage of insertion at gels of different thickness produced greater alignment in thicker gels than thinner gels. For example, inserting a needle 3 mm into a 4 mm-thick gel and rotating the needle produced more alignment than the same procedure in a 6 mm-thick gel (inverted triangles, Figure 10A and 10B). However, inserting a needle 75% into a 6 mm-thick gel (squares, Figure 10B) produces more alignment than 75% into a 4 mm gel (inverted triangles, Figure 10A).

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