Raman spectroscopy delineates radiation-induced injury and partial rescue by amifostine in bone: a murine mandibular model

Zoledronate treatment exerts sex-independent effects on bone and dental physicochemical properties in mice jaw necrosis

INTRODUCTION

Bisphosphonate (BF) therapy is strongly related to the occurrence of medication-related osteonecrosis of the jaw (ONJ). However, no previous study has evaluated if there are sex-related differences on the ONJ establishment together with bone biomechanical alterations, and if they could have a synergy with the ZA treatment.

MATERIALS AND METHODS

This study aimed to analyze the physicochemical properties of mineralized tissues in a zoledronate (ZA)-related osteonecrosis mouse model, by a 2 × 2-factorial design, considering sex (female/male) and treatment (ZA/Saline) factors (n = 8/group). After three ZA (1.0 mg/kg) or saline administrations (days 0, 7, 14), the lower left second molar was extracted (day 42). Further ZA administration (day 49) and euthanasia (day 70) were conducted. After confirmation of ZA-induced jaw necrosis (histologic and microtomographic analysis), spectroscopic and mechanical parameters were assessed.

RESULTS

ZA-treated groups presented lower bone density due to impaired healing of tooth extraction socket. Sex-related alterations were also observed, with lower bone density in females. Regarding biomechanical parameters, sex and treatment exerted independent influences. ZA, although decreasing flexural modulus and yield stress, increases stiffness mainly due to a higher bone volume. Females show less resistance to higher loads compared to males (considering dimension-independent parameters). Additionally, ZA increases crystallinity in bone and dental structure (p < 0.05). In summary, although strongly related to osteonecrosis occurrence, ZA modifies bone and dental mineral matrix, improving bone mechanical properties.

CONCLUSION

Despite sex-dependent differences in bone biomechanics and density, osteonecrosis was established with no sex influence. No synergistic association between sex and treatment factors was observed in this study.

Irradiation Induced Biochemical Changes in Human Mandibular Bone: A Raman Spectroscopic Study

Understanding the biochemical changes in irradiated human mandible after radiotherapy of cancer patients is critical for oral rehabilitation. The underlying mechanism for radiation-associated changes in the bone at the molecular level could lead to implant failure and osteoradionecrosis. The study aimed to assess the chemical composition and bone quality in irradiated human mandibular bone using Raman spectroscopy. A total of 33 bone biopsies from 16 control and 17 irradiated patients were included to quantify different biochemical parameters from the Raman spectra. The differences in bone mineral and matrix band intensities between control and irradiated groups were analyzed using unpaired Student's t-test with statistical significance at p < 0.05. Findings suggest that the intensity of the phosphate band is significantly decreased and the carbonate band is significantly increased in the irradiated group. Further, the mineral crystallinity and carbonate to phosphate ratio are increased. The mineral to matrix ratio is decreased in the irradiated group. Principal component analysis (PCA) based on the local radiation dose and biopsy time interval of irradiated samples did not show any specific classification between irradiation sub-groups. Irradiation disrupted the interaction and bonding between the organic matrix and hydroxyapatite minerals affecting the bone biochemical properties. However, the normal clinical appearance of irradiated bone would have been accompanied by underlying biochemical and microscopical changes which might result in radiation-induced delayed complications.

Overcoming Nuclear Winter: The Cutting-edge Science of Bone Healing and Regeneration in Irradiated Fields

Background:

The incidence of cancer worldwide is expected to be more than 22 million annually by 2030. Approximately half of these patients will likely require radiation therapy. Although radiotherapy has been shown to improve disease control and increase survivorship, it also results in damage to adjacent healthy tissues, including the bone, which can lead to devastating skeletal complications, such as nonunion, pathologic fractures, and osteoradionecrosis. Pathologic fractures and osteoradionecrosis are ominous complications that can result in large bone and soft tissue defects requiring complex reconstruction. Current clinical management strategies for these conditions are suboptimal and dubious at best. The gold standard in treatment of severe radiation injury is free tissue transfer; however, this requires a large operation that is limited to select candidates.

Methods:

With the goal to expand current treatment options and to assuage the devastating sequelae of radiation injury on surrounding normal tissue, our laboratory has performed years of translational studies aimed at remediating bone healing and regeneration in irradiated fields. Three therapeutics (amifostine, deferoxamine, and adipose-derived stem cells) have demonstrated great promise in promoting healing and regeneration of irradiated bone.

Results:

Amifostine confers prophylactic protection, whereas deferoxamine and adipose-derived stem cells function to remediate postradiation associated injury.

Conclusions:

These prospective therapeutics exploit a mechanism attributed to increasing angiogenesis and ultimately function to protect or restore cellularity, normal cellular function, osteogenesis, and bone healing to nonirradiated metrics. These discoveries may offer innovative treatment alternatives to free tissue transfer with the added benefit of potentially preventing and treating osteoradionecrosis and pathologic fractures

Assessment of Renal Osteodystrophy via Computational Analysis of Label-free Raman Detection of Multiple Biomarkers

Accurate clinical evaluation of renal osteodystrophy (ROD) is currently accomplished using invasive in vivo transiliac bone biopsy, followed by in vitro histomorphometry. In this study, we demonstrate that an alternative method for ROD assessment is through a fast, label-free Raman recording of multiple biomarkers combined with computational analysis for predicting the minimally required number of spectra for sample classification at defined accuracies. Four clinically relevant biomarkers: the mineral-to-matrix ratio, the carbonate-to-matrix ratio, phenylalanine, and calcium contents were experimentally determined and simultaneously considered as input to a linear discriminant analysis (LDA). Additionally, sample evaluation was performed with a linear support vector machine (LSVM) algorithm, with a 300 variable input. The computed probabilities based on a single spectrum were only marginally different (~80% from LDA and ~87% from LSVM), both providing an unacceptable classification power for a correct sample assignment. However, the Type I and Type II assignment errors confirm that a relatively small number of independent spectra (7 spectra for Type I and 5 spectra for Type II) is necessary for a p < 0.05 error probability. This low number of spectra supports the practicality of future in vivo Raman translation for a fast and accurate ROD detection in clinical settings.

Medicinal Thiols: Current Status and New Perspectives

The thiol (-SH) functional group is found in a number of drug compounds and confers a unique combination of useful properties. Thiol-containing drugs can reduce radicals and other toxic electrophiles, restore cellular thiol pools, and form stable complexes with heavy metals such as lead, arsenic, and copper. Thus, thiols can treat a variety of conditions by serving as radical scavengers, GSH prodrugs, or metal chelators. Many of the compounds discussed here have been in use for decades, yet continued exploration of their properties has yielded new understanding in recent years, which can be used to optimize their clinical application and provide insights into the development of new treatments. The purpose of this narrative review is to highlight the biochemistry of currently used thiol drugs within the context of developments reported in the last five years. More specifically, this review focuses on thiol drugs that represent the standard of care for their associated conditions, including N-acetylcysteine, 2,3-meso-dimercaptosuccinic acid, British anti-Lewisite, D-penicillamine, amifostine, and others. Reports of novel dosing regimens, delivery strategies, and clinical applications for these compounds were examined with an eye toward emerging approaches to address a wide range of medical conditions in the future.

Amifostine inhibited the differentiation of RAW264.7 cells into osteoclasts by reducing the production of ROS under 2 Gy radiation

Patients with malignant tumors receive radiotherapy, and radiation could harm the skeletal system, leading to radiation-induced osteoporosis. A major cause of this phenomenon is the activation of osteoclasts by radiotherapy. In this study, we studied whether amifostine (AMI) could affect the differentiation of osteoclast precursor cells (RAW264.7 cells) into osteoclasts under 2 gray (Gy) radiation. Four groups were used in the experiment: (a) 0 Gy (no radiation); (b) 0 Gy + AMI; (c) 2 Gy radiation; and (d) 2 Gy radiation + AMI. After radiation, a proliferation assay, a reactive oxygen species (ROS) assay, a comet assay, Trap staining, reverse transcription polymerase chain reaction, and an animal study to test the effect of AMI on osteoclast precursor cells under 2 Gy radiation were conducted. Cell proliferation was significantly inhibited by AMI (P < .05). In addition, 2 Gy radiation led to longer "comet tails", high level of ROS, and more Trap-positive cells in vivo and in vitro (P < .05). Radiation improved the expression of CSTK, NFAT, and Rankl/OPG gene (P < .05), as well as Trap-5b levels in the serum, and decreased bone mineral density. AMI inhibited the differentiation of RAW264.7 cells, shortened the tail moment length of comets, and decreased the level of ROS induced by radiation. The expression of NFAT, CTSK, and Rankl/OPG was decreased by AMI at the detection time point in radiation groups (P < .05). AMI inhibits the maturation and differentiation of osteoclasts under radiation conditions by reducing DNA damage and ROS induced by radiation, thereby reducing the adverse effects of radiation in the skeletal system, indicating that AMI might be used to treat osteoradionecrosis.

Amifostine Suppresses the Side Effects of Radiation on BMSCs by Promoting Cell Proliferation and Reducing ROS Production

This study is aimed at investigating the effect of amifostine (AMI) on rat bone marrow stromal stem cells (BMSCs) exposed to 2 Gy radiation. The BMSCs were divided into four groups, namely, group A that received 0 Gy radiation, group B that received 0 Gy radiation and AMI, group C that received 2 Gy radiation, and group D that received 2 Gy radiation and AMI. The proliferation, apoptosis, and distribution of BMSCs in the cell cycle, along with their osteogenesis ability, adipogenesis ability, and ROS production, were subsequently examined. The levels of ALP, PPARγ, P53, and TNFα were determined by Western blotting. The results demonstrated that the proliferation of BMSCs and the levels of ALP in group C were much lower than those in group A. The production of ROS and levels of PPARγ, P53, and TNFα in the group that received 2 Gy radiation were much higher than those in group A. Furthermore, the production of ROS and the levels of PPARγ, P53, and TNFα were much lower in group D than in group C. Additionally, the levels of ALP and extent of cell proliferation were much higher in group D than in group C. The results demonstrated the potential of AMI in reducing the side effects of radiation in BMSCs and in treatment of bone diseases caused by radiation.

Biological and Medical Applications of Multivariate Curve Resolution Assisted Raman Spectroscopy

Biological specimens such as cells, tissues and biofluids (urine, blood) contain mixtures of many different biomolecules, all of which contribute to a Raman spectrum at any given point. The separation and identification of pure biochemical components remains one of the biggest challenges in Raman spectroscopy. Multivariate curve resolution, a matrix factorization method, is a powerful, yet flexible, method that can be used with constraints, such as non-negativity, to decompose a complex spectroscopic data matrix into a small number of physically meaningful pure spectral components along with their relative abundances. This paper reviews recent applications of multivariate curve resolution by alternating least squares analysis to Raman spectroscopic and imaging data obtained either in vivo or in vitro from biological and medical samples.

Pharmacological interventions for the prevention of insufficiency fractures and avascular necrosis associated with pelvic radiotherapy in adults

BACKGROUND

Pelvic radiotherapy is a treatment delivered to an estimated 150,000 to 300,000 people annually across high-income countries. Fractures due to normal stresses on weakened bone due to radiotherapy are termed insufficiency fractures. Pelvic radiotherapy-related interruption of the blood supply to the hip is termed avascular necrosis and is another recognised complication. The reported incidences of insufficiency fractures are 2.7% to 89% and risk of developing avascular necrosis is 0.5%. These complications lead to significant morbidity in terms of pain, immobility and consequently risk of infections, pressure sores and mortality.

OBJECTIVES

To assess the effects of pharmacological interventions for preventing insufficiency fractures and avascular necrosis in adults over 18 years of age undergoing pelvic radiotherapy.

SEARCH METHODS

We performed electronic literature searches in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and DARE to 19 April 2017. We also searched trial registries. Further relevant studies were identified through handsearching of citation lists of included studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or non RCTs with concurrent comparison groups including quasi-RCTs, cluster RCTs, prospective cohort studies and case series of 30 or more participants were screened. We included studies assessing the effect of pharmacological interventions in adults over 18 years of age undergoing radical pelvic radiotherapy as part of anticancer treatment for a primary pelvic malignancy. We excluded studies involving radiotherapy for bone metastases. We assessed use of pharmacological interventions at any stage before or during pelvic radiotherapy. Interventions included calcium or vitamin D (or both) supplementation, bisphosphonates, selective oestrogen receptor modulators, hormone replacement therapy (oestrogen or testosterone), denosumab and calcitonin.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. We contacted study authors to obtain missing data. Data were to be pooled using the random-effects model if study comparisons were similar, otherwise results were to be reported narratively.

MAIN RESULTS

We included two RCTs (1167 participants). The first RCT compared zoledronic acid with placebo in 96 men undergoing pelvic radiotherapy for non-metastatic prostate cancer.The second RCT had four treatment arms, two of which evaluated zoledronic acid plus adjuvant androgen suppression compared with androgen suppression only in 1071 men undergoing pelvic radiotherapy for non-metastatic prostate cancer.Both studies were at a moderate to high risk of bias and all evidence was judged to be of very low certainty.The studies provided no evidence on the primary outcomes of the review and provided limited data in relation to secondary outcomes, such that meta-analyses were not possible. Both studies focused on interventions to improve bone health in relation to androgen deprivation rather than radiation-related insufficiency fractures and avascular necrosis. Few fractures were described in each study and those described were not specific to insufficiency fractures secondary to radiotherapy. Both studies reported that zoledronic acid in addition to androgen deprivation and pelvic radiotherapy led to improvements in BMD; however, the changes in BMD were measured and reported differently. There was no available evidence regarding adverse effects.

AUTHORS' CONCLUSIONS

The evidence relating to interventions to prevent insufficiency fractures and avascular necrosis associated with pelvic radiotherapy in adults is of very low certainty. This review highlights the need for prospective clinical trials using interventions prior to and during radiotherapy to prevent radiation-related bone morbidity, insufficiency fractures and avascular necrosis. Future trials could involve prospective assessment of bone health including BMD and bone turnover markers prior to pelvic radiotherapy. The interventions for investigation could begin as radiotherapy commences and remain ongoing for 12 to 24 months. Bone turnover markers and BMD could be used as surrogate markers for bone health in addition to radiographic imaging to report on presence of insufficiency fractures and development of avascular necrosis. Clinical assessments and patient reported outcomes would help to identify any associated adverse effects of treatment and quality of life outcomes.

Novel Formulation Strategy to Improve the Feasibility of Amifostine Administration

PURPOSE

Amifostine (AMF), a radioprotectant, is FDA-approved for intravenous administration in cancer patients receiving radiation therapy (XRT). Unfortunately, it remains clinically underutilized due to adverse side effects. The purpose of this study is to define the pharmacokinetic profile of an oral AMF formulation potentially capable of reducing side effects and increasing clinical feasibility.

METHODS

Calvarial osteoblasts were radiated under three conditions: no drug, AMF, and WR-1065 (active metabolite). Osteogenic potential of cells was measured using alkaline phosphatase staining. Next, rats were given AMF intravenously or directly into the jejunum, and pharmacokinetic profiles were evaluated. Finally, rats were given AMF orally or subcutaneously, and blood samples were analyzed for pharmacokinetics.

RESULTS

WR-1065 preserved osteogenic potential of calvarial osteoblasts after XRT to a greater degree than AMF. Direct jejunal AMF administration incurred a systemic bioavailability of 61.5%. Subcutaneously administrated AMF yielded higher systemic levels, a more rapid peak exposure (0.438 vs. 0.875 h), and greater total systemic exposure of WR-1065 (116,756 vs. 16,874 ng*hr/ml) compared to orally administered AMF.

CONCLUSIONS

Orally administered AMF achieves a similar systemic bioavailability and decreased peak plasma level of WR-1065 compared to intravenously administered AMF, suggesting oral AMF formulations maintain radioprotective efficacy without causing onerous side effects, and are clinically feasible.

Raman microscopy of bladder cancer cells expressing green fluorescent protein

Gene engineering is a commonly used tool in cellular biology to determine changes in function or expression of downstream targets. However, the impact of genetic modulation on biochemical effects is less frequently evaluated. The aim of this study is to use Raman microscopy to assess the biochemical effects of gene silencing on T24 and UMUC-13 bladder cancer cell lines. Cellular biochemical information related to nucleic acid and lipogenic components was obtained from deconvolved Raman spectra. We show that the green fluorescence protein (GFP), the chromophore that served as a fluorescent reporter for gene silencing, could also be detected by Raman microscopy. Only the gene-silenced UMUC-13 cell lines exhibited low-to-moderate GFP fluorescence as determined by fluorescence imaging and Raman spectroscopic studies. Moreover, we show that gene silencing and cell phenotype had a greater effect on nucleic acid and lipogenic components with minimal interference from GFP expression. Gene silencing was also found to perturb cellular protein secondary structure in which the amount of disorderd protein increased at the expense of more ordered protein. Overall, our study identified the spectral signature for cellular GFP expression and elucidated the effects of gene silencing on cancer cell biochemistry and protein secondary structure.

Parathyroid hormone attenuates radiation-induced increases in collagen crosslink ratio at periosteal surfaces of mouse tibia

As part of our ongoing efforts to understand underlying mechanisms contributing to radiation-associated bone fragility and to identify possible treatments, we evaluated the longitudinal effects of parathyroid hormone (PTH) treatment on bone quality in a murine model of limited field irradiation. We hypothesized PTH would mitigate radiation-induced changes in the chemical composition and structure of bone, as measured by microscope-based Raman spectroscopy. We further hypothesized that collagen crosslinking would be especially responsive to PTH treatment. Raman spectroscopy was performed on retrieved tibiae (6-7/group/time point) to quantify metrics associated with bone quality, including: mineral-to-matrix ratio, carbonate-to-phosphate ratio, mineral crystallinity, collagen crosslink (trivalent:divalent) ratio, and the mineral and matrix depolarization ratios. Irradiation disrupted the molecular structure and orientation of bone collagen, as evidenced by a higher collagen crosslink ratio and lower matrix depolarization ratio (vs. non-irradiated control bones), persisting until 12weeks post-irradiation. Radiation transiently affected the mineral phase, as evidenced by increased mineral crystallinity and mineral-to-matrix ratio at 4weeks compared to controls. Radiation decreased bone mineral depolarization ratios through 12weeks, indicating increased mineral alignment. PTH treatment partially attenuated radiation-induced increases in collagen crosslink ratio, but did not restore collagen or mineral alignment. These post-radiation matrix changes are consistent with our previous studies of radiation damage to bone, and suggest that the initial radiation damage to bone matrix has extensive effects on the quality of tissue deposited thereafter. In addition to maintaining bone quality, preventing initial radiation damage to the bone matrix (i.e. crosslink ratio, matrix orientation) may be critical to preventing late-onset fragility fractures.