Radiation-induced sarcomas following childhood cancer - A Canadian Sarcoma Research and Clinical Collaboration Study (CanSaRCC)

BACKGROUND

Radiation-induced sarcoma (RIS) is a late toxicity of radiation therapy (RT) usually associated with poor prognosis. Due to ongoing improvements in childhood cancer treatment and patient outcomes, RIS may become more prevalent notwithstanding evolving indications for RT. Due to limited reported studies, we sought to review our experience with RIS in survivors of pediatric cancer.

METHODOLOGY

Data were collected on RIS patients following treatment for childhood cancer (initial diagnosis <18 years) identified in the CanSaRCC database. Additionally, details on the protocol guidance at time of treatment were compared with current guidelines for the same disease.

RESULTS

Among 12 RIS identified, median age at initial diagnosis was 3.5 years (range 0.16-14) and the latency from RT to RIS diagnosis was 24.5 (range 5.4-46.2) years. Initial diagnoses included neuroblastoma, rhabdomyosarcoma, Ewing sarcoma, Wilms tumor, retinoblastoma and Hodgkin's Lymphoma. RIS histologies included osteosarcoma and soft tissue sarcomas. In comparison to protocols followed at time of diagnosis to current ones (2022), 7/12 (58%) patients would have required RT. RIS treatment included chemotherapy, radiation and surgery in 3/11 (27%), 10/11 (90%), and 7/11 (63%) patients, respectively. With a median follow-up time of 4.7 years from diagnosis of RIS, 8 (66%) patients were alive and 4 (33%) had died of progressive RIS.

CONCLUSION

RIS is a serious late effect of radiotherapy in childhood cancer; however, radiation remains an integral component of primary tumor management and requires participation from a specialized multi-disciplinary team, aiming to mitigate RIS and other potential late effects.

A New Microfluidic Platform for Studying Natural Killer Cell and Dendritic Cell Interactions

The importance of the bi-directional natural killer–dendritic cell crosstalk in coordinating anti-tumour and anti-microbial responses in vivo has been well established. However, physical parameters associated with natural killer–dendritic cell interactions have not been fully elucidated. We have previously used a simple “Y” shaped microfluidic device to study natural killer cell-migratory responses toward chemical gradients from a conditioned medium of dendritic cells. There are, however, limitations of the Y-shaped microfluidic devices that could not support higher throughput analyses and studies of cell–cell interactions. Here, we report two novel microfluidic devices (D³-Chip, T²-Chip) we applied in advanced studies of natural killer-cell migrations and their interactions with dendritic cells in vitro. The D³-Chip is an improved version of the previously published Y-shaped device that supports high-throughput analyses and docking of the cells of interest in the migration assay before they are exposed to a chemical gradient. The T²-Chip is created to support analyses of natural killer–dendritic cell cell–cell interactions without the requirement of promoting a natural killer cell to migrate long distances to find a loaded dendritic cell in the device. Using these two microfluidic platforms, we observe quantitative differences in the abilities of the immature and lipopolysaccharide-activated mature dendritic cells to interact with activated natural killer cells. The contact time between the activated natural killer cells and immature dendritic cells is significantly longer than that of the mature dendritic cells. There is a significantly higher frequency of an immature dendritic cell coming into contact with multiple natural killer cells and/or making multiple simultaneous contacts with multiple natural killer cells. To contrast, an activated natural killer cell has a significantly higher frequency of coming into contact with the mature dendritic cells than immature dendritic cells. Collectively, these differences in natural killer–dendritic cell interactions may underlie the differential maturation of immature dendritic cells by activated natural killer cells. Further applications of these microfluidic devices in studying natural killer–dendritic cell crosstalk under defined microenvironments shall enrich our understanding of the functional regulations of natural killer cells and dendritic cells in the natural killer–dendritic cell crosstalk.

A bioenergetic mechanism for amoeboid-like cell motility profiles tested in a microfluidic electrotaxis assay

The amoeboid-like cell motility is known to be driven by the acidic enzymatic hydrolysis of ATP in the actin-myosin system. However, the electro-mechano-chemical coupling, whereby the free energy of ATP hydrolysis is transformed into the power of electrically polarized cell movement, is poorly understood. Previous experimental studies showed that actin filaments motion, cytoplasmic streaming, and muscle contraction can be reconstituted under actin-activated ATP hydrolysis by soluble non-filamentous myosin fragments. Thus, biological motility was demonstrated in the absence of a continuous protein network. These results lead to an integrative conceptual model for cell motility, which advocates an active role played by intracellular proton currents and cytoplasmic streaming (iPC-CS). In this model, we propose that protons and fluid currents develop intracellular electric polarization and pressure gradients, which generate an electro-hydrodynamic mode of amoeboid motion. Such energetic proton currents and active streaming are considered to be mainly driven by stereospecific ATP hydrolysis through myosin heads along oriented actin filaments. Key predictions of this model are supported by microscopy visualization and in-depth sub-population analysis of purified human neutrophils using a microfluidic electrotaxis assay. Three distinct phases in cell motility profiles, morphology, and cytoplasmic streaming in response to physiological ranges of chemoattractant stimulation and electric field application are revealed. Our results support an intrinsic electric dipole formation linked to different patterns of cytoplasmic streaming, which can be explained by the iPC-CS model. Collectively, this alternative biophysical mechanism of cell motility provides new insights into bioenergetics with relevance to potential new biomedical applications.

Mkit: A cell migration assay based on microfluidic device and smartphone

Mobile sensing based on the integration of microfluidic device and smartphone, so-called MS2 technology, has enabled many applications over recent years, and continues to stimulate growing interest in both research communities and industries. In particular, it has been envisioned that MS2 technology can be developed for various cell functional assays to enable basic research and clinical applications. Toward this direction, in this paper, we describe the development of a MS2-based cell functional assay for testing cell migration (the Mkit). The system is constructed as an integrated test kit, which includes microfluidic chips, a smartphone-based imaging platform, the phone apps for image capturing and data analysis, and a set of reagent and accessories for performing the cell migration assay. We demonstrated that the Mkit can effectively measure purified neutrophil and cancer cell chemotaxis. Furthermore, neutrophil chemotaxis can be tested from a drop of whole blood using the Mkit with red blood cell (RBC) lysis. The effects of chemoattractant dose and gradient profile on neutrophil chemotaxis were also tested using the Mkit. In addition to research applications, we demonstrated the effective use of the Mkit for on-site test at the hospital and for testing clinical samples from chronic obstructive pulmonary disease patient. Thus, this developed Mkit provides an easy and integrated experimental platform for cell migration related research and potential medical diagnostic applications.

Correction: A bioenergetic mechanism for amoeboid-like cell motility profiles tested in a microfluidic electrotaxis assay

Correction for 'A bioenergetic mechanism for amoeboid-like cell motility profiles tested in a microfluidic electrotaxis assay' by Hagit Peretz-Soroka et al., Integr. Biol., 2017, DOI: .

Fibroblast growth factor 23 weakens chemotaxis of human blood neutrophils in microfluidic devices

Neutrophil trafficking in tissues critically regulates the body’s immune response. Neutrophil migration can either play a protective role in host defense or cause health problems. Fibroblast growth factor 23 (FGF23) is a known biomarker for chronic kidney disease (CKD) and was recently shown to impair neutrophil arrest on endothelium and transendothelial migration. In the present study, we further examined the effect of FGF23 on human blood neutrophil chemotaxis using two new microfluidic devices. Our results showed that chemotaxis of FGF23 pre-treated neutrophils to a fMLP gradient, in the presence or absence of a uniform FGF23 background, is quantitatively lower compared to the control cells. This effect is accompanied with a stronger drifting of FGF23 pre-treated cells along the flow. However, without the FGF23 pre-treatment, the FGF23 background only reduces chemotaxis of transmigrated cells through the thin barrier channel to the fMLP gradient. The effect of FGF23 on neutrophil migration and the correlation between multiple cell migration parameters are further revealed by chemotactic entropy and principle component analysis. Collectively, these results revealed the effect of FGF23 on weakening neutrophil chemotaxis, which shed light on FGF23 mediated neutrophil migration with direct disease relevance such as CKD.

A dual-docking microfluidic cell migration assay (D2-Chip) for testing neutrophil chemotaxis and the memory effect

Chemotaxis is a classic mechanism for guiding cell migration and an important topic in both fundamental cell biology and health sciences. Neutrophils are a widely used model to study eukaryotic cell migration and neutrophil chemotaxis itself can lead to protective or harmful immune actions to the body. While much has been learnt from past research about how neutrophils effectively navigate through a chemoattractant gradient, many interesting questions remain unclear. For example, while it is tempting to model neutrophil chemotaxis using the well-established biased random walk theory, the experimental proof was challenged by the cell's highly persistent migrating nature. A special experimental design is required to test the key predictions from the random walk model. Another question that has interested the cell migration community for decades concerns the existence of chemotactic memory and its underlying mechanism. Although chemotactic memory has been suggested in various studies, a clear quantitative experimental demonstration will improve our understanding of the migratory memory effect. Motivated by these questions, we developed a microfluidic cell migration assay (so-called dual-docking chip or D2-Chip) that can test both the biased random walk model and the memory effect for neutrophil chemotaxis on a single chip enabled by multi-region gradient generation and dual-region cell alignment. Our results provide experimental support for the biased random walk model and chemotactic memory for neutrophil chemotaxis. Quantitative data analyses provide new insights into neutrophil chemotaxis and memory by making connections to entropic disorder, cell morphology and oscillating migratory response.

Novel developments in mobile sensing based on the integration of microfluidic devices and smartphones

Portable electronic devices and wireless communication systems enable a broad range of applications such as environmental and food safety monitoring, personalized medicine and healthcare management. Particularly, hybrid smartphone and microfluidic devices provide an integrated solution for the new generation of mobile sensing applications. Such mobile sensing based on microfluidic devices (broadly defined) and smartphones (MS(2)) offers a mobile laboratory for performing a wide range of bio-chemical detection and analysis functions such as water and food quality analysis, routine health tests and disease diagnosis. MS(2) offers significant advantages over traditional platforms in terms of test speed and control, low cost, mobility, ease-of-operation and data management. These improvements put MS(2) in a promising position in the fields of interdisciplinary basic and applied research. In particular, MS(2) enables applications to remote in-field testing, homecare, and healthcare in low-resource areas. The marriage of smartphones and microfluidic devices offers a powerful on-chip operating platform to enable various bio-chemical tests, remote sensing, data analysis and management in a mobile fashion. The implications of such integration are beyond telecommunication and microfluidic-related research and technology development. In this review, we will first provide the general background of microfluidic-based sensing, smartphone-based sensing, and their integration. Then, we will focus on several key application areas of MS(2) by systematically reviewing the important literature in each area. We will conclude by discussing our perspectives on the opportunities, issues and future directions of this emerging novel field.

Manipulating and Monitoring On-Surface Biological Reactions by Light-Triggered Local pH Alterations

Significant research efforts have been dedicated to the integration of biological species with electronic elements to yield smart bioelectronic devices. The integration of DNA, proteins, and whole living cells and tissues with electronic devices has been developed into numerous intriguing applications. In particular, the quantitative detection of biological species and monitoring of biological processes are both critical to numerous areas of medical and life sciences. Nevertheless, most current approaches merely focus on the "monitoring" of chemical processes taking place on the sensing surfaces, and little efforts have been invested in the conception of sensitive devices that can simultaneously "control" and "monitor" chemical and biological reactions by the application of on-surface reversible stimuli. Here, we demonstrate the light-controlled fine modulation of surface pH by the use of photoactive molecularly modified nanomaterials. Through the use of nanowire-based FET devices, we showed the capability of modulating the on-surface pH, by intensity-controlled light stimulus. This allowed us simultaneously and locally to control and monitor pH-sensitive biological reactions on the nanodevices surfaces, such as the local activation and inhibition of proteolytic enzymatic processes, as well as dissociation of antigen-antibody binding interactions. The demonstrated capability of locally modulating the on-surface effective pH, by a light stimuli, may be further applied in the local control of on-surface DNA hybridization/dehybridization processes, activation or inhibition of living cells processes, local switching of cellular function, local photoactivation of neuronal networks with single cell resolution and so forth.

Optically-gated self-calibrating nanosensors: monitoring pH and metabolic activity of living cells

Quantitative detection of biological and chemical species is critical to numerous areas of medical and life sciences. In this context, information regarding pH is of central importance in multiple areas, from chemical analysis, through biomedical basic studies and medicine, to industry. Therefore, a continuous interest exists in developing new, rapid, miniature, biocompatible and highly sensitive pH sensors for minute fluid volumes. Here, we present a new paradigm in the development of optoelectrical sensing nanodevices with built-in self-calibrating capabilities. The proposed electrical devices, modified with a photoactive switchable molecular recognition layer, can be optically switched between two chemically different states, each having different chemical binding constants and as a consequence affecting the device surface potential at different extents, thus allowing the ratiometric internal calibration of the sensing event. At each point in time, the ratio of the electrical signals measured in the ground and excited states, respectively, allows for the absolute concentration measurement of the molecular species under interest, without the need for electrical calibration of individual devices. Furthermore, we applied these devices for the real-time monitoring of cellular metabolic activity, extra- and intracellularly, as a potential future tool for the performance of basic cell biology studies and high-throughput personalized medicine-oriented research, involving single cells and tissues. This new concept can be readily expanded to the sensing of additional chemical and biological species by the use of additional photoactive switchable receptors. Moreover, this newly demonstrated coupling between surface-confined photoactive molecular species and nanosensing devices could be utilized in the near future in the development of devices of higher complexity for both the simultaneous control and monitoring of chemical and biological processes with nanoscale resolution control.