TY - JOUR
T1 - The free diffusion of macromolecules in tissue-engineered skeletal muscle subjected to large compression strains
AU - Gefen, Amit
AU - Cornelissen, Lisette H.
AU - Gawlitta, Debby
AU - Bader, Dan L.
AU - Oomens, Cees W.J.
PY - 2008
Y1 - 2008
N2 - Pressure-related deep tissue injury (DTI) represents a severe pressure ulcer, which initiates in compressed muscle tissue overlying a bony prominence and progresses to more superficial tissues until penetrating the skin. Individual subjects with impaired motor and/or sensory capacities are at high risk of developing DTI. Impaired diffusion of critical metabolites in compressed muscle tissue may contribute to DTI, and impaired diffusion of tissue damage biomarkers may further impose a problem in developing early detection blood tests. We hypothesize that compression of muscle tissue between a bony prominence and a supporting surface locally influences the diffusion capacity of muscle. The objective of this study was therefore, to determine the effects of large compression strains on free diffusion in a tissue-engineered skeletal muscle model. Diffusion was measured with a range of fluorescently labeled dextran molecules (10, 20, 150 kDa) whose sizes were representative of both hormones and damage biomarkers. We used fluorescence recovery after photobleaching (FRAP) to compare diffusion coefficients (D) of the different dextrans between the uncompressed and compressed (48-60% strain) states. In a separate experiment, we simulated the effects of local partial muscle ischemia in vivo, by reducing the temperature of compressed specimens from 37 to 34 °C. Compared to the D in the uncompressed model system, values in the compressed state were significantly reduced by 47±22% (p<0.02). A 3 °C temperature decrease further reduced D in the compressed specimens by 10±6% (p<0.05). In vivo, the effects of large strains and ischemia are likely to be summative, and hence, the present findings suggest an important role of impaired diffusion in the etiology of DTI, and should also be considered when developing biochemical screening methods for early detection of DTI.
AB - Pressure-related deep tissue injury (DTI) represents a severe pressure ulcer, which initiates in compressed muscle tissue overlying a bony prominence and progresses to more superficial tissues until penetrating the skin. Individual subjects with impaired motor and/or sensory capacities are at high risk of developing DTI. Impaired diffusion of critical metabolites in compressed muscle tissue may contribute to DTI, and impaired diffusion of tissue damage biomarkers may further impose a problem in developing early detection blood tests. We hypothesize that compression of muscle tissue between a bony prominence and a supporting surface locally influences the diffusion capacity of muscle. The objective of this study was therefore, to determine the effects of large compression strains on free diffusion in a tissue-engineered skeletal muscle model. Diffusion was measured with a range of fluorescently labeled dextran molecules (10, 20, 150 kDa) whose sizes were representative of both hormones and damage biomarkers. We used fluorescence recovery after photobleaching (FRAP) to compare diffusion coefficients (D) of the different dextrans between the uncompressed and compressed (48-60% strain) states. In a separate experiment, we simulated the effects of local partial muscle ischemia in vivo, by reducing the temperature of compressed specimens from 37 to 34 °C. Compared to the D in the uncompressed model system, values in the compressed state were significantly reduced by 47±22% (p<0.02). A 3 °C temperature decrease further reduced D in the compressed specimens by 10±6% (p<0.05). In vivo, the effects of large strains and ischemia are likely to be summative, and hence, the present findings suggest an important role of impaired diffusion in the etiology of DTI, and should also be considered when developing biochemical screening methods for early detection of DTI.
KW - Confocal microscopy
KW - Deep tissue injury
KW - Dextran
KW - FRAP
KW - Pressure ulcer
UR - http://www.scopus.com/inward/record.url?scp=39649099372&partnerID=8YFLogxK
U2 - 10.1016/j.jbiomech.2007.10.023
DO - 10.1016/j.jbiomech.2007.10.023
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C2 - 18068175
AN - SCOPUS:39649099372
SN - 0021-9290
VL - 41
SP - 845
EP - 853
JO - Journal of Biomechanics
JF - Journal of Biomechanics
IS - 4
ER -