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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

Complex stiffness (N/m) 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 complex stiffness behaviour of samples immediately after thawing and plot B identifies the complex stiffness behaviour after 4 hours storage at 22°C. They both reveal no mean complex stiffness differences among the various storage temperatures.
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Figure 2: Complex stiffness (N/m) 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 complex stiffness behaviour of samples immediately after thawing and plot B identifies the complex stiffness behaviour after 4 hours storage at 22°C. They both reveal no mean complex stiffness differences among the various storage temperatures.

Mentions: The mean complex stiffness values for treatment and control groups at either testing time were not significantly different (p > 0.3) (Figure 2). Although the stiffness of samples stored at -80°C appears elevated in the second mechanical test, it was not significantly higher (p > 0.5). The consistency in stiffness levels between the 0 hour and 4 hour tests of control samples indicates the non-destructive nature of the testing procedure and the reliability of the mechanical analyses.


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

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

Complex stiffness (N/m) 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 complex stiffness behaviour of samples immediately after thawing and plot B identifies the complex stiffness behaviour after 4 hours storage at 22°C. They both reveal no mean complex stiffness differences among the various storage temperatures.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Complex stiffness (N/m) 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 complex stiffness behaviour of samples immediately after thawing and plot B identifies the complex stiffness behaviour after 4 hours storage at 22°C. They both reveal no mean complex stiffness differences among the various storage temperatures.
Mentions: The mean complex stiffness values for treatment and control groups at either testing time were not significantly different (p > 0.3) (Figure 2). Although the stiffness of samples stored at -80°C appears elevated in the second mechanical test, it was not significantly higher (p > 0.5). The consistency in stiffness levels between the 0 hour and 4 hour tests of control samples indicates the non-destructive nature of the testing procedure and the reliability of the mechanical analyses.

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