The phenotype and value of nerve conduction studies in measuring chemotherapy-induced peripheral neuropathy: A secondary analysis of pooled data.

PURPOSE: Nerve conduction studies (NCS) have been suggested as gold standard for diagnosing and monitoring peripheral neuropathies. However, its value in measuring chemotherapy-induced peripheral neuropathy (CIPN) is not clearly understood. Our study aimed to examine the role and performance of NCS in CIPN assessment through a secondary analysis. METHODS: Pooled data pertaining to NCS, clinical examination, symptoms, and quality of life from patients with cancer enrolled in five studies were used. These patients had received taxane- or oxaliplatin-based chemotherapy. The data were grouped in cohorts of before initiation of chemotherapy, during chemotherapy, at the end of chemotherapy, and at recovery stage according to the time points of assessment in the original studies. RESULTS: Data was available from a total of 84 patients (74 females and 10 males) and a total of 160 NCS assessments. NCS results confirmed that damage of sensory nerves is more profound than motor nerves in patients at different stages of neurotoxic chemotherapy. No strong correlation was identified between NCS parameters and clinical examination outcomes as well as patient-reported symptoms and quality of life. NCS did not perform well in discriminating clinically relevant CIPN (area under the curve [AUC] = 0.51-0.77). CONCLUSIONS: Our findings suggest that NCS may have limited value in diagnosing CIPN. Future prospective studies with baseline values are needed to clarify our tentative conclusions.

Prevention of Oxaliplatin-Induced Peripheral Neuropathy: A Systematic Review and Meta-Analysis.

BACKGROUND: Oxaliplatin-induced peripheral neuropathy (OIPN) has significant clinical impact on the quality of life for cancer patients and is a dose limiting toxicity. Trials studying preventive measures have been inconclusive. A systematic review and meta-analysis were conducted to evaluate the existing pharmacological and non-pharmacological interventions to prevent chronic OIPN. METHODS: Literature databases PubMed-MEDLINE, Embase and Scopus, were searched from 1 Jan 2005 to 08 Aug 2020 and major conferences' abstracts were reviewed for randomized controlled trials that examined the efficacy of any preventive measure for OIPN. The primary outcome measure was the incidence of chronic OIPN with a preventive intervention as compared to placebo or no intervention. The pooled risk ratio and its 95% confidence interval were calculated using a random effects model. A network meta-analysis was conducted to derive indirect evidence of any preventive effect of an intervention against placebo when original trials compared one intervention against another. RESULTS: Forty-four trials were analyzed describing 29 chemoprotective interventions, including combinations, and 1 non-pharmacological intervention. Ratings were assessed via a combination of outcomes with quality assessment using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) framework. Of the 30 interventions examined, there were six interventions supporting potential efficacy, 11 interventions with insufficient evidence and 13 interventions not recommended. CONCLUSION: Currently, there is insufficient certainty to support any intervention as effective in preventing OIPN. Of note is that most of these studies have focused on pharmacological interventions; non-pharmacological interventions are underexplored. Further research on ways to limit OIPN is needed. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=225095, Prospero Registration Number: CRD42021225095.

Distinct spatio-temporal and spectral brain patterns for different thermal stimuli perception.

Understanding the human brain's perception of different thermal sensations has sparked the interest of many neuroscientists. The identification of distinct brain patterns when processing thermal stimuli has several clinical applications, such as phantom-limb pain prediction, as well as increasing the sense of embodiment when interacting with neurorehabilitation devices. Notwithstanding the remarkable number of studies that have touched upon this research topic, understanding how the human brain processes different thermal stimuli has remained elusive. More importantly, very intense thermal stimuli perception dynamics, their related cortical activations, as well as their decoding using effective features are still not fully understood. In this study, using electroencephalography (EEG) recorded from three healthy human subjects, we identified spatial, temporal, and spectral patterns of brain responses to different thermal stimulations ranging from extremely cold and hot stimuli (very intense), moderately cold and hot stimuli (intense), to a warm stimulus (innocuous). Our results show that very intense thermal stimuli elicit a decrease in alpha power compared to intense and innocuous stimulations. Spatio-temporal analysis reveals that in the first 400 ms post-stimulus, brain activity increases in the prefrontal and central brain areas for very intense stimulations, whereas for intense stimulation, high activity of the parietal area was observed post-500 ms. Based on these identified EEG patterns, we successfully classified the different thermal stimulations with an average test accuracy of 84% across all subjects. En route to understanding the underlying cortical activity, we source localized the EEG signal for each of the five thermal stimuli conditions. Our findings reveal that very intense stimuli were anticipated and induced early activation (before 400 ms) of the anterior cingulate cortex (ACC). Moreover, activation of the pre-frontal cortex, somatosensory, central, and parietal areas, was observed in the first 400 ms post-stimulation for very intense conditions and starting 500 ms post-stimuli for intense conditions. Overall, despite the small sample size, this work presents novel findings and a first comprehensive approach to explore, analyze, and classify EEG-brain activity changes evoked by five different thermal stimuli, which could lead to a better understanding of thermal stimuli processing in the brain and could, therefore, pave the way for developing a real-time withdrawal reaction system when interacting with prosthetic limbs. We underpin this last point by benchmarking our EEG results with a demonstration of a real-time withdrawal reaction of a robotic prosthesis using a human-like artificial skin.

Cryotherapy for Prevention of Taxane-Induced Peripheral Neuropathy: A Meta-Analysis.

PURPOSE: Taxanes are widely used in gynecological cancer therapy, however, taxane-induced peripheral neuropathy (TIPN) limits chemotherapy dose and reduces patients' quality of life. As a safe and convenient intervention, cryotherapy has been recommended as a promising intervention in the recent clinical guidelines for the prevention of TIPN. Although there are a considerable number of studies which explored the use of cryotherapy in preventing chemotherapy-induced peripheral neuropathy (CIPN), there is insufficient large-scale clinical evidence. We performed a meta-analysis on the current available evidence to examine whether cryotherapy can prevent TIPN in cancer patients receiving taxanes. METHODS: We searched databases including PubMed, Embase, and Cochrane from inception to August 3, 2021 for eligible trials. Clinical trials that examined the efficacy of cryotherapy for prevention of TIPN were included. The primary outcome was the incidence of TIPN, and secondary outcomes were incidence of taxane dose reduction and changes in nerve conduction studies. The meta-analysis software (RevMan 5.3) was used to analyze the data. RESULTS: We analyzed 2250 patients from 9 trials. Assessments using the Common Terminology Criteria for Adverse Events (CTCAE) score showed that cryotherapy could significantly reduce the incidence of motor and sensory neuropathy of grade≥2 (sensory: RR 0.65, 95%CI 0.56 to 0.75, p<0.00001; motor: RR 0.18, 95% CI [0.03, 0.94], p=0.04). When evaluated using the Patient Neuropathy Questionnaire (PNQ), cryotherapy demonstrated significant reduction in the incidence of sensory neuropathy (RR 0.11, 95% CI 0.04 to 0.31], p<0.0001), but did not show significant reduction in the incidence of motor neuropathy (RR 0.46, 95% CI 0.11 to 1.88, p=0.28). Cryotherapy was associated with reduced incidences of taxane dose reduction due to TIPN (RR 0.48, 95% CI [0.24, 0.95], p=0.04) and had potential to preserve motor nerves. CONCLUSIONS: Cryotherapy is likely to prevent TIPN in patients receiving taxanes. High quality and sufficient amount of evidence is warranted.

Personalised, Rational, Efficacy-Driven Cancer Drug Dosing via an Artificial Intelligence SystEm (PRECISE): A Protocol for the PRECISE CURATE.AI Pilot Clinical Trial.

Introduction: Oncologists have traditionally administered the maximum tolerated doses of drugs in chemotherapy. However, these toxicity-guided doses may lead to suboptimal efficacy. CURATE.AI is an indication-agnostic, mechanism-independent and efficacy-driven personalised dosing platform that may offer a more optimal solution. While CURATE.AI has already been applied in a variety of clinical settings, there are no prior randomised controlled trials (RCTs) on CURATE.AI-guided chemotherapy dosing for solid tumours. Therefore, we aim to assess the technical and logistical feasibility of a future RCT for CURATE.AI-guided solid tumour chemotherapy dosing. We will also collect exploratory data on efficacy and toxicity, which will inform RCT power calculations. Methods and analysis: This is an open-label, single-arm, two-centre, prospective pilot clinical trial, recruiting adults with metastatic solid tumours and raised baseline tumour marker levels who are planned for palliative-intent, capecitabine-based chemotherapy. As CURATE.AI is a small data platform, it will guide drug dosing for each participant based only on their own tumour marker levels and drug doses as input data. The primary outcome is the proportion of participants in whom CURATE.AI is successfully applied to provide efficacy-driven personalised dosing, as judged based on predefined considerations. Secondary outcomes include the timeliness of dose recommendations, participant and physician adherence to CURATE.AI-recommended doses, and the proportion of clinically significant dose changes. We aim to initially enrol 10 participants from two hospitals in Singapore, perform an interim analysis, and consider either cohort expansion or an RCT. Recruitment began in August 2020. This pilot clinical trial will provide key data for a future RCT of CURATE.AI-guided personalised dosing for precision oncology. Ethics and dissemination: The National Healthcare Group (NHG) Domain Specific Review Board has granted ethical approval for this study (DSRB 2020/00334). We will distribute our findings at scientific conferences and publish them in peer-reviewed journals. Trial registration number: NCT04522284.

A Systematic Review and Meta-Analysis of the Effectiveness of Neuroprotectants for Paclitaxel-Induced Peripheral Neuropathy.

BACKGROUND: Paclitaxel-induced peripheral neuropathy (PIPN) is a disabling side effect of paclitaxel with few effective preventive strategies. We aim to determine the efficacy of pharmacological and non-pharmacological neuroprotective interventions in preventing PIPN incidence. METHODS: Biomedical literature databases were searched from years 2000 to 2021 for trials comparing neuroprotective interventions and control. Meta-analysis was performed using the random-effects model. The primary outcome was the incidence of PIPN. RESULTS: Of 24 relevant controlled trials, 14 were eligible for meta-analysis. Pooled results from seven non-pharmacological trials were associated with a statistically significant 48% relative reduction of PIPN risk with low heterogeneity. Conversely, pooled results from six pharmacological trials were associated with a significant 20% relative reduction of PIPN risk with moderate heterogeneity. Both pharmacological and non-pharmacological approaches appear effective in reducing PIPN incidence in the treatment arm compared to control (pooled RR < 1). CONCLUSION: Current evidence suggests that both interventions may reduce PIPN risk. Non-pharmacological interventions appear more effective than pharmacological interventions.

Limb Hypothermia for the Prevention of Chemotherapy-Induced Peripheral Neuropathy - Modality for Optimal Cooling.

Chemotherapy-induced peripheral neuropathy (CIPN) is a common dose-limiting adverse effect of neurotoxic chemotherapeutic agents. Recent studies have suggested clinical utility of limb hypothermia in reducing CIPN. However, conventional cooling methods such as ice packs are unable to provide thermoregulated cooling and cause frostbites. Cooling modalities offering thermoregulation have been developed for sports injury and orthopaedic indications, but not explored for preventing CIPN. This study aims to determine the safety, tolerability and optimal parameters of three cooling modalities for delivery of limb hypothermia in healthy subjects, prior to testing in cancer patients for prevention of CIPN. Healthy subjects underwent limb hypothermia by either: continuous-flow cooling, cryocompression or frozen gloves. Skin temperatures and tolerance scores were monitored. Overall, 58 subjects underwent limb hypothermia. No adverse events were observed barring transient erythema. Both continuous-flow cooling and cryocompression are feasible, safe and tolerable methods for delivery of limb hypothermia. Cryocompression achieved lower skin temperatures than continuous-flow cooling with similar safety profiles. Frozen gloves were minimally tolerated. Cryocompression may provide greater efficacy in preventing CIPN, with clinical trials currently underway.

Megavoltage Radiosensitization of Gold Nanoparticles on a Glioblastoma Cancer Cell Line Using a Clinical Platform.

Gold nanoparticles (GNPs) have demonstrated significant dose enhancement with kilovoltage (kV) X-rays; however, recent studies have shown inconsistent findings with megavoltage (MV) X-rays. We propose to evaluate the radiosensitization effect on U87 glioblastoma (GBM) cells in the presence of 42 nm GNPs and irradiated with a clinical 6 MV photon beam. Cytotoxicity and radiosensitization were measured using MTS and clonogenic cellular radiation sensitivity assays, respectively. The sensitization enhancement ratio was calculated for 2 Gy (SER2Gy) with GNP (100 µg/mL). Dark field and MTS assays revealed high co-localization and good biocompatibility of the GNPs with GBM cells. A significant sensitization enhancement of 1.45 (p = 0.001) was observed with GNP 100 µg/mL. Similarly, at 6 Gy, there was significant difference in the survival fraction between the GBM alone group (mean (M) = 0.26, standard deviation (SD) = 0.008) and the GBM plus GNP group (M = 0.07, SD = 0.05, p = 0.03). GNPs enabled radiosensitization in U87 GBM cells at 2 Gy when irradiated using a clinical platform. In addition to the potential clinical utility of GNPs, these studies demonstrate the effectiveness of a robust and easy to standardize an in-vitro model that can be employed for future studies involving metal nanoparticle plus irradiation.

A Limb Hypothermia Wearable for Chemotherapy-Induced Peripheral Neuropathy: A Mixed-Methods Approach in Medical Product Development.

Chemotherapy-Induced Peripheral Neuropathy (CIPN) is a common dose-limiting side-effect of taxane-based chemotherapy, causing progressive and often irreversible pain/sensitivity in the hands and feet. Prevention/treatments for CIPN are not well-developed and urgently needed. Limb cryocompression during chemotherapy has demonstrated promising early data of preventing/reducing CIPN severity. Currently there are no medical devices available that are dedicated to the specific requirements of CIPN prevention. As part of our ongoing development of a dedicated CIPN-prevention limb cryocompression system, this study documents the design & development of the wearable arm wrap, a central component of the system, from initial concept to a trial-ready prototype. A collaborative and multidisciplinary approach was adopted to address the complex and high-risk nature of this SME (Small Medium Enterprise)-centered medical device design & development process. The complementary collaboration unites multidisciplinary expertise spanning the scope of the project. Alongside the clinical, academic, and design & development expertise, the integration of commercial expertise is imperative to promote the market viability, and ultimate success, of the development. As the global leading experts in scalp cooling specializing in the prevention of chemotherapy-induced alopecia, UK-based SME Paxman Coolers Ltd is optimally positioned to support the commercial and regulatory dimensions. Development and adoption of a novel mixed-methodology (HudPAX) facilitated the integration of evidence-based and user-centered techniques to optimize the design & development approach and ensure integration of all critical design inputs. Alpha prototypes were designed through evidence-based approaches, with data from existing clinical trials utilized to determine the preliminary design inputs, alongside 3D ergonomic data. Investigations utilized computer-aided design, rapid prototyping, additive manufacturing, sketch modeling, and fast ideation. User-based approaches facilitated stakeholder-feedback through expert focus groups, informing further design & development and projecting the design into the next stage, Beta prototyping, for use in large-scale efficacy trials and upscaling manufacturing. This paper demonstrates a novel mixed-methods approach, which promotes cross-sector multidisciplinary collaboration, to address the complex multi-layered challenges posed by an early-stage medical device design & development process.

Activation of sphingosine 1-phosphate receptor 2 attenuates chemotherapy-induced neuropathy.

Platinum-based therapeutics are used to manage many forms of cancer, but frequently result in peripheral neuropathy. Currently, the only option available to attenuate chemotherapy-induced neuropathy is to limit or discontinue this treatment. Sphingosine 1-phosphate (S1P) is a lipid-based signaling molecule involved in neuroinflammatory processes by interacting with its five cognate receptors: S1P1-5 In this study, using a combination of drug pharmacodynamic analysis in human study participants, disease modeling in rodents, and cell-based assays, we examined whether S1P signaling may represent a potential target in the treatment of chemotherapy-induced neuropathy. To this end, we first investigated the effects of platinum-based drugs on plasma S1P levels in human cancer patients. Our analysis revealed that oxaliplatin treatment specifically increases one S1P species, d16:1 S1P, in these patients. Although d16:1 S1P is an S1P2 agonist, it has lower potency than the most abundant S1P species (d18:1 S1P). Therefore, as d16:1 S1P concentration increases, it is likely to disproportionately activate proinflammatory S1P1 signaling, shifting the balance away from S1P2 We further show that a selective S1P2 agonist, CYM-5478, reduces allodynia in a rat model of cisplatin-induced neuropathy and attenuates the associated inflammatory processes in the dorsal root ganglia, likely by activating stress-response proteins, including ATF3 and HO-1. Cumulatively, the findings of our study suggest that the development of a specific S1P2 agonist may represent a promising therapeutic approach for the management of chemotherapy-induced neuropathy.

Safety and tolerability of cryocompression as a method of enhanced limb hypothermia to reduce taxane-induced peripheral neuropathy.

PURPOSE: Severe peripheral neuropathy is a common dose-limiting toxicity of taxane chemotherapy, with no effective treatment. Frozen gloves have shown to reduce the severity of neuropathy in several studies but comes with the incidence of undesired side effects such as cold intolerance and frostbite in extreme cases. A device with thermoregulatory features which can safely deliver tolerable amounts of cooling while ensuring efficacy is required to overcome the deficiencies of frozen gloves. The role of continuous-flow cooling in prevention of neurotoxicity caused by paclitaxel has been previously described. This study hypothesized that cryocompression (addition of dynamic pressure to cooling) may allow for delivery of lower temperatures with similar tolerance and potentially improve efficacy. METHOD: A proof-of-concept study was conducted in cancer patients receiving taxane chemotherapy. Each subject underwent four-limb cryocompression with each chemotherapy infusion (three hours) for a maximum of 12 cycles. Cryocompression was administered at 16 °C and cyclic pressure (5-15 mmHg). Skin surface temperature and tolerance scores were recorded. Neuropathy was assessed using clinician-graded peripheral sensory neuropathy scores, total neuropathy score (TNS) and nerve conduction studies (NCS) conducted before (NCSpre), after completion (NCSpost) and 3 months post-chemotherapy (NCS3m). Results were retrospectively compared with patients who underwent paclitaxel chemotherapy along with continuous-flow cooling and controls with no hypothermia. RESULTS: In total, 13 patients underwent 142 cycles of cryocompression concomitant with chemotherapy. Limb hypothermia was well tolerated, and only 1 out of 13 patients required an intra-cycle temperature increase, with no early termination of cryocompression in any subject. Mean skin temperature reduction of 3.8 ± 1.7 °C was achieved. Cryocompression demonstrated significantly greater skin temperature reductions compared to continuous-flow cooling and control (p < 0.0001). None of the patients experienced severe neuropathy (clinician-assessed neuropathy scores of grade 2 or higher). NCS analysis showed preservation of motor amplitudes at NCS3m in subjects who underwent cryocompression, compared to the controls who showed significant deterioration (NCS3m cryocompression vs. NCS3m control: ankle stimulation: 8.1 ± 21.4%, p = 0.004; below fibula head stimulation: 12.7 ± 25.6%, p = 0.0008; above fibula head stimulation: 9.4 ± 24.3%, p = 0.002). Cryocompression did not significantly affect taxane-induced changes in sensory nerve amplitudes. CONCLUSION: When compared to continuous-flow cooling, cryocompression permitted delivery of lower temperatures with similar tolerability. The lower skin surface temperatures achieved potentially lead to improved efficacy in neurotoxicity amelioration. Larger studies investigating cryocompression are required to validate these findings.

Minimal clinically important difference of the EORTC QLQ-CIPN20 for worsening peripheral neuropathy in patients receiving neurotoxic chemotherapy.

CONTEXT/OBJECTIVES: This is the first study to determine the minimal clinically important difference (MCID) of the European Organisation of Research and Treatment of Cancer Quality of Life Questionnaire-CIPN twenty-item scale (EORTC QLQ-CIPN20), a validated instrument designed to elicit cancer patients' experience of symptoms and functional limitations related to chemotherapy-induced peripheral neuropathy. METHODS: Cancer patients receiving neurotoxic chemotherapy completed EORTC QLQ-CIPN20 and the Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity [FACT/GOG-NTX] at baseline, second cycle of chemotherapy (T2, n = 287), and 12 months after chemotherapy (T3, n = 191). Anchor-based approach used the validated FACT/GOG-NTX neurotoxicity (Ntx) subscale to identify optimal MCID cutoff for deterioration. Distribution-based approach used one-third standard deviation (SD), half SD, and one standard error of measurement of the total EORTC QLQ-CIPN20 score. RESULTS: There was a moderate correlation between the change scores of the Ntx subscale and sensory and motor subscales of QLQ-CIPN20 (T2: r = - 0.722, p < 0.001 and r = - 0.518, p < 0.001, respectively; T3: r = - 0.699; p < 0.001 and r = - 0.523, p < 0.001, respectively). The correlation between the change scores of the Ntx subscale and the QLQ-CIPN20 autonomic subscale was poor (T2: r = - 0.354, p < 0.001; T3: r = 0.286, p < 0.001). Based on the MCID derived using distribution-based method, the MCID for the QLQ-CIPN20 sensory subscale was 2.5-5.9 (6.9% to 16.4% of the subdomain score) and for motor subscale was 2.6-5.0 (8.1%-15.6% of the subdomain score). CONCLUSION: The MCID for the EORTC QLQ-CIPN20 established using distribution-based approaches was 2.5-5.9 for the sensory subscale and 2.6-5.0 for the motor subscale. When noted in assessments even with small change in scores, clinicians can be alerted for appropriate intervention.

Are we mis-estimating chemotherapy-induced peripheral neuropathy? Analysis of assessment methodologies from a prospective, multinational, longitudinal cohort study of patients receiving neurotoxic chemotherapy.

BACKGROUND: There are inconsistencies in the literature regarding the prevalence and assessment of chemotherapy-induced peripheral neuropathy (CIPN). This study explored CIPN natural history and its characteristics in patients receiving taxane- and platinum-based chemotherapy. PATIENTS AND METHODS: Multi-country multisite prospective longitudinal observational study. Patients were assessed before commencing and three weekly during chemotherapy for up to six cycles, and at 6,9, and 12 months using clinician-based scales (NCI-CTCAE; WHO-CIPN criterion), objective assessments (cotton wool test;10 g monofilament); patient-reported outcome measures (FACT/GOG-Ntx; EORTC-CIPN20), and Nerve Conduction Studies. RESULTS: In total, 343 patients were recruited in the cohort, providing 2399 observations. There was wide variation in CIPN prevalence rates using different assessments (14.2-53.4%). Prevalence of sensory neuropathy (and associated symptom profile) was also different in each type of chemotherapy, with paclitaxel (up to 63%) and oxaliplatin (up to 71.4%) showing the highest CIPN rates in most assessments and a more complex symptom profile. Peak prevalence was around the 6-month assessment (up to 71.4%). Motor neurotoxicity was common, particularly in the docetaxel subgroup (up to 22.1%; detected by NCI-CTCAE). There were relatively moderately-to-low correlations between scales (rs = 0.15,p < 0.05-rs = 0.48 p < 0.001), suggesting that they measure different neurotoxicity aspects from each other. Cumulative chemotherapy dose was not associated with onset and course of CIPN. CONCLUSION: The historical variation reported in CIPN incidence and prevalence is possibly confounded by disagreement between assessment modalities. Clinical practice should consider assessment of motor neuropathy for neurotoxic chemotherapy. Current scales may not be all appropriate to measure CIPN in a valid way, and a combination of scales are needed.

Engineering the Infrared Luminescence and Photothermal Properties of Double-Shelled Rare-Earth-Doped Nanoparticles for Biomedical Applications.

The nascent field of theranostics, which couples targeted therapy with diagnostics, has catalyzed efforts toward improved nanoprobe designs that facilitate both localized treatment and diagnostic imaging. Rare-earth-doped nanoparticles (RENPs) have emerged as a leading candidate for theranostics because of their versatile synthesis and modification chemistries, photostability, and relative safety. Furthermore, their bright, tunable fluorescence using near-infrared (NIR) excitation enables multispectral imaging with high signal-to-background ratios. In this work, we have synthesized double-shelled RENPs with tunable properties for optimal fluorescent imaging, photoacoustic imaging, and photothermal therapy. The properties of the double-shelled RENPs were tailored by controlling the density of rare-earth ions (i.e., activator or sensitizer) by using either a functional amorphous organic or a crystalline outermost shell. This study systematically analyzes the effects of the functional organic or inorganic outermost shell on the imaging and photothermal conversion properties of our RENPs. Despite the weaker infrared absorption enhancement, the functional organic outermost shell impregnated with a low density of rare-earth ions led to minimal reduction of fluorescence emissions. In contrast, the higher density of rare-earth ions in the inorganic shell led to higher infrared absorption and consequently significant reduction in emissions arising from the undesired optical attenuation. Inorganic shell thickness was therefore modified to reduce the deleterious attenuation, leading to brighter emissions that also enabled the in vitro SWIR detection of ∼2500 cells/cluster. Using the enhanced infrared properties that arise from this functional inorganic layer, which could be engineered to respond to either NIR or SWIR, we demonstrated that (1) bright SWIR emissions allowed detection of small cell clusters; (2) strong PA signals allowed clear visualization of particle distribution within tumors; and (3) strong photothermal effects resulted in localized elevated temperatures. Collectively, these results highlight the utility of these double-shelled RENPs as theranostic agents that are compatible with both photoacoustic or fluorescent imaging platforms.

Molecular Engineering of Photoacoustic Performance by Chalcogenide Variation in Conjugated Polymer Nanoparticles for Brain Vascular Imaging.

As conjugated polymer nanoparticles (CPNs) have attracted growing interest as photoacoustic (PA) imaging contrast agents, revelation of the relationship between the molecular structure of conjugated polymers and PA property is highly in demand. Here, three donor-acceptor-structured conjugated polymer analogs are designed, where only a single heteroatom of acceptor units changes from oxygen to sulfur to selenium, allowing for systematic investigation of the molecular structure-PA property relationship. The absorption and PA spectra of these CPNs can be facilely tuned by changing the heteroatoms of the acceptor units. Moreover, the absorption coefficient, and in turn the PA signal intensity, decreases when the heteroatom changes from oxygen to sulfur to selenium. As these CPNs exhibit weak fluorescence and similar photothermal conversion efficiency (≈70%), their PA intensities are approximately proportional to their absorption coefficients. The in vivo brain vasculature imaging in this study also demonstrates this trend. This study provides a simple but efficient strategy to manipulate the PA properties of CPNs through changing the heteroatom at key positions.

Simultaneous functional photoacoustic microscopy and electrocorticography reveal the impact of rtPA on dynamic neurovascular functions after cerebral ischemia.

The advance of thrombolytic therapy has been hampered by the lack of optimization of the therapy during the hyperacute phase of focal ischemia. Here, we investigate neurovascular dynamics using a custom-designed hybrid electrocorticography (ECoG)-functional photoacoustic microscopy (fPAM) imaging system during the hyperacute phase (first 6 h) of photothrombotic ischemia (PTI) in male Wistar rats following recombinant tissue plasminogen activator (rtPA)-mediated thrombolysis. We reported, for the first time, the changes in neural activity and cerebral hemodynamic responses following rtPA infusion at different time points post PTI. Interestingly, very early administration of rtPA (< 1 h post PTI) resulted in only partial recovery of neurovascular dynamics (specifically , neural activity recovered to 71 ± 3.5% of baseline and hemodynamics to only 52 ± 2.6% of baseline) and late administration of rtPA (> 4 h post PTI) resulted in the deterioration of neurovascular function. A therapeutic window between 1 and 3 h post PTI was found to improve recovery of neurovascular function (i.e. significant restoration of neural activity to 93 ± 4.2% of baseline and hemodynamics to 81 ± 2.1% of baseline, respectively). The novel combination of fPAM and ECoG enables direct mapping of neurovascular dynamics and serves as a platform to evaluate potential interventions for stroke.

Integrated treatment modality of cathodal-transcranial direct current stimulation with peripheral sensory stimulation affords neuroprotection in a rat stroke model.

Cathodal-transcranial direct current stimulation induces therapeutic effects in animal ischemia models by preventing the expansion of ischemic injury during the hyperacute phase of ischemia. However, its efficacy is limited by an accompanying decrease in cerebral blood flow. On the other hand, peripheral sensory stimulation can increase blood flow to specific brain areas resulting in rescue of neurovascular functions from ischemic damage. Therefore, the two modalities appear to complement each other to form an integrated treatment modality. Our results showed that hemodynamics was improved in a photothrombotic ischemia model, as cerebral blood volume and hemoglobin oxygen saturation ([Formula: see text]) recovered to 71% and 76% of the baseline values, respectively. Furthermore, neural activities, including somatosensory-evoked potentials (110% increase), the alpha-to-delta ratio (27% increase), and the [Formula: see text] ratio (27% decrease), were also restored. Infarct volume was reduced by 50% with a 2-fold preservation in the number of neurons and a 6-fold reduction in the number of active microglia in the infarct region compared with the untreated group. Grip strength was also better preserved (28% higher) compared with the untreated group. Overall, this nonpharmacological, nonintrusive approach could be prospectively developed into a clinical treatment modality.

Enhanced near-infrared photoacoustic imaging of silica-coated rare-earth doped nanoparticles.

Near-infrared photoacoustic (PA) imaging is an emerging diagnostic technology that utilizes the tissue transparent window to achieve improved contrast and spatial resolution for deep tissue imaging. In this study, we investigated the enhancement effect of the SiO2 shell on the PA property of our core/shell rare-earth nanoparticles (REs) consisting of an active rare-earth doped core of NaYF4:Yb,Er (REDNPs) and an undoped NaYF4 shell. We observed that the PA signal amplitude increased with SiO2 shell thickness. Although the SiO2 shell caused an observed decrease in the integrated fluorescence intensity due to the dilution effect, fluorescence quenching of the rare earth emitting ions within the REDNPs cores was successfully prevented by the undoped NaYF4 shell. Therefore, our multilayer structure consisting of an active core with successive functional layers was demonstrated to be an effective design for dual-modal fluorescence and PA imaging probes with improved PA property. The result from this work addresses a critical need for the development of dual-modal contrast agent that advances deep tissue imaging with high resolution and signal-to-noise ratio.

Low Levels of NDRG1 in Nerve Tissue Are Predictive of Severe Paclitaxel-Induced Neuropathy.

INTRODUCTION: Sensory peripheral neuropathy caused by paclitaxel is a common and dose limiting toxicity, for which there are currently no validated predictive biomarkers. We investigated the relationship between the Charcot-Marie-Tooth protein NDRG1 and paclitaxel-induced neuropathy. METHODS/MATERIALS: Archived mammary tissue specimen blocks of breast cancer patients who received weekly paclitaxel in a single centre were retrieved and NDRG1 immunohistochemistry was performed on normal nerve tissue found within the sample. The mean nerve NDRG1 score was defined by an algorithm based on intensity of staining and percentage of stained nerve bundles. NDRG1 scores were correlated with paclitaxel induced neuropathy. RESULTS: 111 patients were studied. 17 of 111 (15%) developed severe paclitaxel-induced neuropathy. The mean nerve NDRG1 expression score was 5.4 in patients with severe neuropathy versus 7.7 in those without severe neuropathy (p = 0.0019). A Receiver operating characteristic (ROC) curve analysis of the mean nerve NDRG1 score revealed an area under the curve of 0.74 (p = 0.0013) for the identification of severe neuropathy, with a score of 7 being most discriminative. 13/54 (24%) subjects with an NDRG1 score < = 7 developed severe neuropathy, compared to only 4/57 (7%) in those with a score >7 (p = 0.017). CONCLUSION: Low NDRG1 expression in nerve tissue present within samples of surgical resection may identify subjects at risk for severe paclitaxel-induced neuropathy. Since nerve biopsies are not routinely feasible for patients undergoing chemotherapy for early breast cancer, this promising biomarker strategy is compatible with current clinical workflow.

Organic Nanoparticles with Aggregation-Induced Emission for Bone Marrow Stromal Cell Tracking in a Rat PTI Model.

Stem-cell based therapy is an emerging therapeutic approach for ischemic stroke treatment. Bone marrow stromal cells (BMSCs) are in common use as a cell source for stem cell therapy and show promising therapeutic outcomes for stroke treatment. One challenge is to develop a reliable tracking strategy to monitor the fate of BMSCs and assess their therapeutic effects in order to improve the success rate of such treatment. Herein, TPEEP, a fluorogen with aggregation-induced emission characteristics and near-infrared emission are designed and synthesized and further fabricated into organic nanoparticles (NPs). The obtained NPs show high fluorescence quantum yield, low cytotoxicity with good physical and photostability, which display excellent tracking performance of BMSCs in vitro and in vivo. Using a rat photothrombotic ischemia model as an example, the NP-labeled BMSCs are able to migrate to the stroke lesion site to yield bright red fluorescence. Immunofluorescence staining shows that the NP labeling does not affect the normal function of BMSCs, proving their good biocompatibility in vivo. These merits make TPEEP NP a potential cell tracker to evaluate the fate of BMSCs in cell therapy.