Molecular spectroscopic identification of the water compartments in bone

Ünal, Mustafa; Yang, Shan; Akkuş, Ozan

doi:10.1016/j.bone.2014.07.021

Cited by 60 publications

(78 citation statements)

References 41 publications

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“…There are several water compartments in collagen, including surface, within the triple helical structure, or connecting helices that are within the same fibril [83]. Clearly, further detailed studies, which will include deuterium exchange to enable the identification of specific water compartments [42, 48, 84], will be required to better understand the nature of these absorbances.…”

Section: 0 Discussionmentioning

confidence: 99%

“…Both FT-IRIS and Raman have been applied to evaluate collagen quality in harvested bone tissues, with investigations focusing on both enzymatic crosslinks [37, 39] and non-enzymatic crosslinks in the form of advanced glycation end products [40, 41]. Even with the molecular-level information available from such spectroscopic studies, investigations into water interactions in intact bone have been limited [42], and have not included imaging investigations of tissues. Gravimetric analysis is still the standard method for assessment of water in tissue, a destructive technique that does not permit imaging of water distribution.…”

Section: Introductionmentioning

confidence: 99%

“…More importantly, these techniques cannot map bound and free water in cortical bone at spatial resolutions beyond imaging resolution, which is on the order of 0.5mm for whole bone cross section studies[45]. Recently, a custom built short wave Raman spectrometer was utilized to investigate water in bone at high spatial resolution, but such analyses would be challenging using standard Raman spectrometers [42, 52]. …”

Section: Introductionmentioning

confidence: 99%

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Non-destructive NIR spectral imaging assessment of bone water: Comparison to MRI measurements

Rajapakse

Padalkar

Yang

et al. 2017

Bone

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Bone fracture risk increases with age, disease states, and with use of certain therapeutics, such as acid-suppressive drugs, steroids and high-dose bisphosphonates. Historically, investigations into factors that underlie bone fracture risk have focused on evaluation of bone mineral density (BMD). However, numerous studies have pointed to factors other than BMD that contribute to fragility, including changes in bone collagen and water. The goal of this study is to investigate the feasibility of using near infrared spectral imaging (NIRSI) to determine the spatial distribution and relative amount of water and organic components in whole cross-sections of bone, and to compare those results to those obtained using magnetic resonance imaging (MRI) methods. Cadaver human whole-section tibiae samples harvested from 18 donors of ages 27–97 years underwent NIRSI and ultrashort echo time (UTE) MRI. As NIRSI data is comprised of broad absorbances, second derivative processing was evaluated as a means to narrow peaks and obtain compositional information. The (inverted) second derivative peak heights of the NIRSI absorbances correlated significantly with the mean peak integration of the water, collagen and fat NIR absorbances, respectively, indicating that either processing method could be used for compositional assessment. The 5797 cm−1 absorbance was validated as arising from the fat present in bone marrow, as it completely disappeared after ultrasonication. The MRI UTE-determined bound water content in tibial cortical bone samples ranged from 62 to 91%. The NIRSI water peaks at 5152 cm−1 and at 7008 cm−1 correlated significantly with the UTE data, with r = 0.735, p = 0.016, and r = 0.71, p =.0096, respectively. There was also a strong correlation between the intensity of the NIRSI water peak at 7008 cm−1 and the intensity of the collagen peak at 4608 cm−1 (r = 0.69, p = 0.004). Since NIRSI requires minimal to no sample preparation, this approach has great potential to become a gold standard modality for the investigation of changes in water content, distribution, and environment in pre-clinical studies of bone pathology and therapeutics.

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Section: 0 Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Non-destructive NIR spectral imaging assessment of bone water: Comparison to MRI measurements

Rajapakse

Padalkar

Yang

et al. 2017

Bone

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“…Raman spectroscopy can provide unique information on the type of water with various energy levels and the moiety to which water molecules are bound to (25) . Raman spectroscopy has not been used to study the OH-stretch band in bone since the commercial Raman systems lack sensitivity into the OH-stretch range.…”

Section: Introductionmentioning

confidence: 99%

Raman spectral classification of mineral- and collagen-bound water's associations to elastic and post-yield mechanical properties of cortical bone

Ünal

Akkuş

2015

Bone

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Water that is bound to bone’s matrix is implied as a predictor of fracture resistance; however, bound water is an elusive variable to be measured nondestructively. To date, the only nondestructive method used for studying bone hydration status is magnetic resonance variants (NMR or MRI). For the first time, bone hydration status was studied by short-wave infrared (SWIR) Raman spectroscopy to investigate associations of mineral-bound and collagen-bound water compartments with mechanical properties. Thirty cortical bone samples were used for quantitative Raman-based water analysis, gravimetric analysis, porosity measurement, and biomechanical testing. A sequential dehydration protocol was developed to replace unbound (heat drying) and bound (ethanol treatment) water in bone. Raman spectra were collected serially to track the OH-stretch band during dehydration. Four previously identified peaks were investigated: I3220/I2949, I3325/I2949 and I3453/I2949 reflect status of organic-matrix related water (mostly collagen-related water) compartments and collagen portion of bone while I3584/I2949 reflects status of mineral-related water compartments and mineral portion of bone. These spectroscopic biomarkers were correlated with elastic and post-yield mechanical properties of bone. Collagen-water related biomarkers (I3220/I2949 and I3325/I2949) correlated significantly and positively with toughness (R2=0.81 and R2=0.79; p<0.001) and post-yield toughness (R2=0.65 and R2=0.73; p<0.001). Mineral-water related biomarker correlated significantly and negatively with elastic modulus (R2=0.78; p<0.001) and positively with strength (R2=0.46; p < 0.001). While MR-based techniques have been useful in measuring unbound and bound water, this is the first study which probed bound-water compartments differentially for collagen and mineral-bound water. For the first time, we showed an evidence for contributions of different bound-water compartments to mechanical properties of wet bone and the reported correlations of Raman-based water measurements to mechanical properties underline the necessity for enabling approaches to assess these new biomarkers noninvasively in vivo to improve the current diagnosis of those who may be at risk of bone fracture due to aging and diseases.

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“…, articular cartilage) (60–62) . GAGs are also found in the extrafibrillar matrix of bone (21,22) with strong affinity to extrafibrillar minerals (41,63–65) . Collagen-bound water is usually considered as a major source of organic-bound water in bone matrix since type I collagen comprises 90% of the organic matrix of the tissue and is highly hydrophilic (20) .…”

Section: Discussionmentioning

confidence: 99%

Age‐Related Deterioration of Bone Toughness Is Related to Diminishing Amount of Matrix Glycosaminoglycans (GAGs)

et al. 2018

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Hydration status significantly affects the toughness of bone. In addition to the collagen phase, recent evidence shows that glycosaminoglycans (GAGs) of proteoglycans (PGs) in the extracellular matrix also play a pivotal role in regulating the tissue-level hydration status of bone, thereby affecting the tissue-level toughness of bone. In this study, we hypothesized that the amount of GAGs in bone matrix decreased with age and such changes would lead to reduction in bound water and subsequently result in a decrease in the tissue-level toughness of bone. To test the hypothesis, nanoscratch tests were conducted to measure the tissue-level toughness of human cadaveric bone specimens, which were procured only from male donors in three different age groups: young (26 ± 6 years old), mid-aged (52 ± 5 years old) and elderly (73 ± 5 years old), with six donors in each group. Biochemical and histochemical assays were performed to determine the amount and major subtypes of GAGs and proteoglycans in bone matrix. In addition, low-field NMR measurements were implemented to determine bound water content in bone matrix. The results demonstrated that aging resulted in a statistically significant reduction (17%) of GAGs in bone matrix. Concurrently, a significant deterioration (20%) of tissue-level toughness of bone with age was observed. Most importantly, the deteriorated tissue-level toughness of bone was associated significantly with the age-related reduction (40%) of bound water, which was partially induced by the decrease of GAGs in bone matrix. Furthermore, we identified that chondroitin sulfate (CS) was a major subtype of GAGs and the amount of CS decreased with aging in accompany with a decrease of biglycan that is a major subtype of PGs in bone. The findings of this study suggests that reduction of GAGs in bone matrix is likely one of the molecular origins for age-related deterioration of bone quality.

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Molecular spectroscopic identification of the water compartments in bone

Cited by 60 publications

References 41 publications

Non-destructive NIR spectral imaging assessment of bone water: Comparison to MRI measurements

Non-destructive NIR spectral imaging assessment of bone water: Comparison to MRI measurements

Raman spectral classification of mineral- and collagen-bound water's associations to elastic and post-yield mechanical properties of cortical bone

Age‐Related Deterioration of Bone Toughness Is Related to Diminishing Amount of Matrix Glycosaminoglycans (GAGs)

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