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Freeze-thaw treatment effects on the dynamic mechanical properties of articular cartilage.

Szarko M, Muldrew K, Bertram JE - BMC Musculoskelet Disord (2010)

Bottom Line: Both subzero storage temperature as well as freezing rate were compared using control samples (4°C) and samples stored at either -20°C or -80°C as well as samples first snap frozen in liquid nitrogen (-196°C) prior to storage at -80°C.Mechanical changes shown are likely due to ice lens creation, where frost heave effects may have caused collagen damage.That storage to -20°C and -80°C did not alter the mechanical properties of articular cartilage shows that when combined with a rapid thawing protocol to 37.5°C, the tissue may successfully be stored at subzero temperatures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Biomedical Sciences, St. George's, University of London, London, UK.

ABSTRACT

Background: As a relatively non-regenerative tissue, articular cartilage has been targeted for cryopreservation as a method of mitigating a lack of donor tissue availability for transplant surgeries. In addition, subzero storage of articular cartilage has long been used in biomedical studies using various storage temperatures. The current investigation studies the potential for freeze-thaw to affect the mechanical properties of articular cartilage through direct comparison of various subzero storage temperatures.

Methods: Both subzero storage temperature as well as freezing rate were compared using control samples (4°C) and samples stored at either -20°C or -80°C as well as samples first snap frozen in liquid nitrogen (-196°C) prior to storage at -80°C. All samples were thawed at 37.5°C to testing temperature (22°C). Complex stiffness and hysteresis characterized load resistance and damping properties using a non-destructive, low force magnitude, dynamic indentation protocol spanning a broad loading rate range to identify the dynamic viscoelastic properties of cartilage.

Results: Stiffness levels remained unchanged with exposure to the various subzero temperatures. Hysteresis increased in samples snap frozen at -196°C and stored at -80°C, though remained unchanged with exposure to the other storage temperatures.

Conclusions: Mechanical changes shown are likely due to ice lens creation, where frost heave effects may have caused collagen damage. That storage to -20°C and -80°C did not alter the mechanical properties of articular cartilage shows that when combined with a rapid thawing protocol to 37.5°C, the tissue may successfully be stored at subzero temperatures.

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Related in: MedlinePlus

Hysteresis with standard errors (shown at alternating loading rates for each sample) for the means of the loading rates for control samples at 4°C (identified by open circles) and samples frozen to -20°C (identified by open triangles), -80°C (identified by open squares), or snap frozen in liquid nitrogen and stored at -80°C (identified by crosses). Plot A identifies the hysteresis of samples immediately after thawing and plot B identifies the hysteresis after 4 hours storage at 22°C. This figure shows increased levels of viscous flow over faster loading rate frequencies for samples snap frozen in liquid nitrogen and stored at -80°C (A and B) and those frozen at -20°C (B). The small dotted line in plot B represents the 0 hour control data.
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Figure 3: Hysteresis with standard errors (shown at alternating loading rates for each sample) for the means of the loading rates for control samples at 4°C (identified by open circles) and samples frozen to -20°C (identified by open triangles), -80°C (identified by open squares), or snap frozen in liquid nitrogen and stored at -80°C (identified by crosses). Plot A identifies the hysteresis of samples immediately after thawing and plot B identifies the hysteresis after 4 hours storage at 22°C. This figure shows increased levels of viscous flow over faster loading rate frequencies for samples snap frozen in liquid nitrogen and stored at -80°C (A and B) and those frozen at -20°C (B). The small dotted line in plot B represents the 0 hour control data.

Mentions: No significant changes (p > 0.5) were found immediately after thawing between samples stored at subzero temperatures and the 4°C controls (Figure 3a). After four hours of storage at room temperature however, those specimens snap frozen in liquid nitrogen and stored at -80°C showed significantly increased (p < 0.01) phase lag values (approximately a 30% increase), most evident over faster loading rates (> 41 Hz) when compared to control specimens. This mechanical property change suggests that this particular freeze-thaw protocol may have caused extracellular matrix damage (Figure 3b). Mean hysteresis values for samples stored at 4°C were similar to each other over both testing times. The consistency in the control samples between testing times again identifies the reliability of the hysteresis measurements and reflects the non-destructive nature of the mechanical testing procedure.


Freeze-thaw treatment effects on the dynamic mechanical properties of articular cartilage.

Szarko M, Muldrew K, Bertram JE - BMC Musculoskelet Disord (2010)

Hysteresis with standard errors (shown at alternating loading rates for each sample) for the means of the loading rates for control samples at 4°C (identified by open circles) and samples frozen to -20°C (identified by open triangles), -80°C (identified by open squares), or snap frozen in liquid nitrogen and stored at -80°C (identified by crosses). Plot A identifies the hysteresis of samples immediately after thawing and plot B identifies the hysteresis after 4 hours storage at 22°C. This figure shows increased levels of viscous flow over faster loading rate frequencies for samples snap frozen in liquid nitrogen and stored at -80°C (A and B) and those frozen at -20°C (B). The small dotted line in plot B represents the 0 hour control data.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2958988&req=5

Figure 3: Hysteresis with standard errors (shown at alternating loading rates for each sample) for the means of the loading rates for control samples at 4°C (identified by open circles) and samples frozen to -20°C (identified by open triangles), -80°C (identified by open squares), or snap frozen in liquid nitrogen and stored at -80°C (identified by crosses). Plot A identifies the hysteresis of samples immediately after thawing and plot B identifies the hysteresis after 4 hours storage at 22°C. This figure shows increased levels of viscous flow over faster loading rate frequencies for samples snap frozen in liquid nitrogen and stored at -80°C (A and B) and those frozen at -20°C (B). The small dotted line in plot B represents the 0 hour control data.
Mentions: No significant changes (p > 0.5) were found immediately after thawing between samples stored at subzero temperatures and the 4°C controls (Figure 3a). After four hours of storage at room temperature however, those specimens snap frozen in liquid nitrogen and stored at -80°C showed significantly increased (p < 0.01) phase lag values (approximately a 30% increase), most evident over faster loading rates (> 41 Hz) when compared to control specimens. This mechanical property change suggests that this particular freeze-thaw protocol may have caused extracellular matrix damage (Figure 3b). Mean hysteresis values for samples stored at 4°C were similar to each other over both testing times. The consistency in the control samples between testing times again identifies the reliability of the hysteresis measurements and reflects the non-destructive nature of the mechanical testing procedure.

Bottom Line: Both subzero storage temperature as well as freezing rate were compared using control samples (4°C) and samples stored at either -20°C or -80°C as well as samples first snap frozen in liquid nitrogen (-196°C) prior to storage at -80°C.Mechanical changes shown are likely due to ice lens creation, where frost heave effects may have caused collagen damage.That storage to -20°C and -80°C did not alter the mechanical properties of articular cartilage shows that when combined with a rapid thawing protocol to 37.5°C, the tissue may successfully be stored at subzero temperatures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Biomedical Sciences, St. George's, University of London, London, UK.

ABSTRACT

Background: As a relatively non-regenerative tissue, articular cartilage has been targeted for cryopreservation as a method of mitigating a lack of donor tissue availability for transplant surgeries. In addition, subzero storage of articular cartilage has long been used in biomedical studies using various storage temperatures. The current investigation studies the potential for freeze-thaw to affect the mechanical properties of articular cartilage through direct comparison of various subzero storage temperatures.

Methods: Both subzero storage temperature as well as freezing rate were compared using control samples (4°C) and samples stored at either -20°C or -80°C as well as samples first snap frozen in liquid nitrogen (-196°C) prior to storage at -80°C. All samples were thawed at 37.5°C to testing temperature (22°C). Complex stiffness and hysteresis characterized load resistance and damping properties using a non-destructive, low force magnitude, dynamic indentation protocol spanning a broad loading rate range to identify the dynamic viscoelastic properties of cartilage.

Results: Stiffness levels remained unchanged with exposure to the various subzero temperatures. Hysteresis increased in samples snap frozen at -196°C and stored at -80°C, though remained unchanged with exposure to the other storage temperatures.

Conclusions: Mechanical changes shown are likely due to ice lens creation, where frost heave effects may have caused collagen damage. That storage to -20°C and -80°C did not alter the mechanical properties of articular cartilage shows that when combined with a rapid thawing protocol to 37.5°C, the tissue may successfully be stored at subzero temperatures.

Show MeSH
Related in: MedlinePlus