Label-Free Multiphoton Microscopy: Much More Than Fancy Images

Multiphoton microscopy has recently passed the milestone of its first 30 years of activity in biomedical research. The growing interest around this approach has led to a variety of applications from basic research to clinical practice. Moreover, this technique offers the advantage of label-free multiphoton imaging to analyze samples without staining processes and the need for a dedicated system. Here, we review the state of the art of label-free techniques; then, we focus on two-photon autofluorescence as well as second and third harmonic generation, describing physical and technical characteristics. We summarize some successful applications to a plethora of biomedical research fields and samples, underlying the versatility of this technique. A paragraph is dedicated to an overview of sample preparation, which is a crucial step in every microscopy experiment. Afterwards, we provide a detailed review analysis of the main quantitative methods to extract important information and parameters from acquired images using second harmonic generation. Lastly, we discuss advantages, limitations, and future perspectives in label-free multiphoton microscopy.

Relationship between hemoglobin, hemolysis, and transcranial Doppler velocities in children with sickle cell disease: Results from a long-term natural history study in Italy in the era of multimodal therapy

BACKGROUND

Stroke and cerebral vasculopathy are leading causes of morbidity and mortality in patients with sickle cell disease (SCD). Transcranial Doppler (TCD) is a reliable and validated predictor of stroke risk. Children with conditional or abnormal TCD are at an increased risk for stroke, which can be mitigated by red blood cell transfusion or hydroxyurea. Elucidating the relationship between cerebral hemodynamics and hemolytic anemia can help identify novel therapeutic approaches to reduce stroke risk and transfusion dependence.

METHODS

This long-term, real-world study was designed to evaluate the prevalence of TCD imaging (TCDi)-assessed flow velocities in children and to interrogate their relationship with markers of anemia and hemolysis.

RESULTS

In total, 155 children (median follow-up 79.8 months, 1358.44 patient-years) had 583 evaluable TCDi results. Only patients with HbSS or HbSβ⁰ had abnormal (1.6%) or conditional (10.9%) TCDi. Children with abnormal or conditional TCDi had lower hemoglobin (Hb) and higher hemolysis markers. A linear correlation was detected between TCD velocity and Hb: an Hb increase of 1 g/dL corresponded to decreases in velocity in the internal carotid and middle cerebral arteries (6.137 cm/s and 7.243 cm/s). Moreover, patients with Hb >9 g/dL presented a lower risk of TCDi-associated events.

CONCLUSION

These results support the need to optimize disease-modifying treatments that increase Hb and reduce hemolysis for stroke prevention in young children with SCD.

Acute chest syndrome in children with sickle cell disease: Data from a national AIEOP cohort identify priority areas of intervention in a hub-and-spoke system

Acute chest syndrome (ACS) is a frequent cause of hospitalization in sickle cell disease (SCD). Despite advances in acute care, many settings still lack knowledge about ACS best practices. After the AIEOP Guidelines were published in 2012, suggesting standardized management in Italy, a retrospective study was performed to assess the diagnostic and therapeutic pathways of ACS in children. From 2013 to 2018, 208 ACS episodes were presented by 122/583 kids in 11 centres. 73 were male, mean age 10.9 years, 85% African, 92% HbSS or Sβ°. In our hub-and-spoke system, a good adherence to Guidelines was documented, but discrepancies between reference centres and general hospitals were noted. Improvement is needed for timely transfer to reference centres, use of incentive spirometry, oxygen therapy and pain management.

Clinical characteristics and outcomes for children, adolescents and young adults with "CIC-fused" or "BCOR-rearranged" soft tissue sarcomas: A multi-institutional European retrospective analysis

BACKGROUND

In certain rare undifferentiated small round cell sarcomas new specific molecular CIC-DUX4/other partner, BCOR-CCNB3/other partner, YWHAE fusions, or BCOR-ITD (internal tandem duplication) were identified. These new "CIC fused" (CIC-fused/ATXN1::NUTM1) and "BCOR rearranged" (BCOR fused/ITD/ YWHAE) soft tissue sarcomas (STS) are not well described.

METHODS

Multi-institutional European retrospective analysis of young patients (0-24 years) with CIC-fused and BCOR rearranged STS.

RESULTS

Overall, out of the 60 patients selected, the fusion status was CIC-fused (n = 29), ATXN1::NUTM1 (n = 2), BCOR::CCNB3 (n = 18), BCOR-ITD (n = 7), and YWHAE (n = 3), MAML::BCOR STS (n = 1). The main primaries were abdomen-pelvic (n = 23) and limbs (n = 18). Median age was 14 years (0.9-23.8) and 0.9 (0.1-19.1) for CIC-fused and BCOR-rearranged groups, respectively (n = 29; p < 0.001). IRS stages were I (n = 3), II (n = 7), III (n = 35), and IV (n = 15). Overall, 42 patients had large tumors (>5 cm) but only six had lymph node involvement. Patients received mainly chemotherapy (n = 57), local surgery (n = 50), and/or radiotherapy (n = 34). After a median follow-up of 47.1 months (range, 3.4-230), 33 (52%) patients had an event and 23 patients died. Three-year event-free survivals were 44.0% (95% CI 28.7-67.5) and 41.2% (95% CI 25.4-67.0) for CIC and BCOR groups (p = 0.97), respectively. Three-year overall survivals were 46.3% (95% CI 29.6-72.4) and 67.1% (95% CI 50.4-89.3; p = 0.24), respectively.

CONCLUSIONS

Pediatric patients often present with large tumors and metastatic disease, especially CIC sarcomas. Overall outcome is dismal. New treatment options are needed.

Hypoxic Human Microglia Promote Angiogenesis Through Extracellular Vesicle Release

Microglia, the brain-resident immune cells, orchestrate neuroinflammatory responses and are crucial in the progression of neurological diseases, including ischemic stroke (IS), which accounts for approximately 85% of all strokes worldwide. Initially deemed detrimental, microglial activation has been shown to perform protective functions in the ischemic brain. Besides their effects on neurons, microglia play a role in promoting post-ischemic angiogenesis, a pivotal step for restoring oxygen and nutrient supply. However, the molecular mechanisms underlying microglia-endothelial cell interactions remain largely unresolved, particularly in humans. Using both in vitro and in vivo models, we investigated the angiogenic signature and properties of extracellular vesicles (EVs) released by human microglia upon hypoxia-reperfusion stimulation. EVs were isolated and characterized in terms of their size, concentration, and protein content. Their angiogenic potential was evaluated using endothelial cell assays and a zebrafish xenograft model. The in vivo effects were further assessed in a mouse model of ischemic stroke. Our findings identified key proteins orchestrating the pro-angiogenic functions of human microglial EVs under hypoxic conditions. In vitro assays demonstrated that hypoxic EVs (hypEVs) promoted endothelial cell migration and tube formation. In vivo, hypEVs induced vessel sprouting in zebrafish and increased microvessel density in the perilesional area of mice following ischemic stroke.

Localized incompletely resected standard risk rhabdomyosarcoma in children and adolescents: Results from the European Paediatric Soft Tissue Sarcoma Study Group RMS 2005 trial

BACKGROUND

The authors report the prospective evaluation of reduced dose alkylator chemotherapy combined with radiotherapy for European Pediatric Soft Tissue Sarcoma Study Group (EpSSG) standard risk nonalveolar rhabdomyosarcoma (NA-RMS).

PATIENTS AND METHODS

Localized node negative Intergroup Rhabdomyosarcoma Study (IRS) II/III NA-RMS at favorable sites (subgroup C), <25 years old, received five cycles of ifosfamide, vincristine, and dactinomycin (IVA) chemotherapy (30 g/m2 ifosfamide) and four cycles of vincristine and dactinomycin (if receiving radiotherapy), or nine cycles of IVA (54 g/m2 ifosfamide) ± radiotherapy. Delayed primary tumor excision was considered for IRS III tumors. The primary end points were event-free survival (EFS) and overall survival (OS).

RESULTS

From October 2005 to December 2016, 359 evaluable patients were recruited: orbit, 164 (45.7%); head and neck nonparameningeal, 77 (21.4%); and genitourinary non-bladder/prostate, 118 (32.9%). EFS and OS were 77.4% (95% confidence interval [CI], 72.5-81.6) and 93.5% (95% CI, 90.1-95.8), respectively. Lower dose alkylator chemotherapy and radiotherapy achieved 5-year OS of 93.7% but the difference with higher dose alkylator chemotherapy +/- radiotherapy was not significant (p = 0.8003). Adjuvant radiotherapy improved EFS with 5-year estimates of 84.7% versus 65.2% for nonirradiated (p < .0001), but not OS (p = .9298). Omitting radiotherapy for orbital tumors reduced OS (5-year was 87.1% vs. 97.3% for irradiated, p = .0257). Following R0 resection (n = 60), radiotherapy did not significantly improve EFS or OS.

CONCLUSIONS

Radiotherapy for local tumor control allows for reduction of cumulative dose of alkylators in EpSSG standard risk subgroup C RMS patients. The omission of radiotherapy did not affect OS in all patients except those with orbital RMS and was associated with inferior EFS.

Early-onset indicators of a hypercoagulable state and clinical complications in a cohort of children with sickle cell trait

Adults with sickle cell trait (SCT) have a procoagulant state with increased risk of thromboembolism, but limited data are available for children. We compared the coagulation profile of children with SCT, different sickle cell disease (SCD) genotypes, and healthy controls. Compared to controls and similarly to HbSC patients, 41 SCT children (mean age 6.85 years; 20 males; 88% Africans) had a characteristic procoagulant profile: higher levels of factor VIII, von Willebrand factor (VWF) Ag and CBA, D-dimer; lower levels of ADAMTS 13 activity, ADAMTS13 activity: VWFAg, plasminogen activator inhibitor, tissue plasminogen activator. Moreover, 13/41 had clinical complications of SCD, five requiring hospitalization.

Molecular and functional profiling of chemotolerant cells unveils nucleoside metabolism-dependent vulnerabilities in medulloblastoma

Chemotherapy resistance is considered one of the main causes of tumor relapse, still challenging researchers for the identification of the molecular mechanisms sustaining its emergence. Here, we setup and characterized chemotherapy-resistant models of Medulloblastoma (MB), one of the most lethal pediatric brain tumors, to uncover targetable vulnerabilities associated to their resistant phenotype. Integration of proteomic, transcriptomic and kinomic data revealed a significant deregulation of several pathways in resistant MB cells, converging to cell metabolism, RNA/protein homeostasis, and immune response, eventually impacting on patient outcome. Moreover, resistant MB cell response to a large library of compounds through a high-throughput screening (HTS), highlighted nucleoside metabolism as a relevant vulnerability of chemotolerant cells, with peculiar antimetabolites demonstrating increased efficacy against them and even synergism with conventional chemotherapeutics. Our results suggest that drug-resistant cells significantly rewire multiple cellular processes, allowing their adaptation to a chemotoxic environment, nevertheless exposing alternative actionable susceptibilities for their specific targeting.

Reappraisal of prognostic factors used in the European Pediatric Soft Tissue Sarcoma Study Group RMS 2005 study for localized rhabdomyosarcoma to optimize risk stratification and generate a prognostic nomogram

BACKGROUND

The objective of this study was to investigate the role of clinical factors together with FOXO1 fusion status in patients with nonmetastatic rhabdomyosarcoma (RMS) to develop a predictive model for event-free survival and provide a rationale for risk stratification in future trials.

METHODS

The authors used data from patients enrolled in the European Pediatric Soft Tissue Sarcoma Study Group (EpSSG) RMS 2005 study (EpSSG RMS 2005; EudraCT number 2005-000217-35). The following baseline variables were considered for the multivariable model: age at diagnosis, sex, histology, primary tumor site, Intergroup Rhabdomyosarcoma Studies group, tumor size, nodal status, and FOXO1 fusion status. Main effects and significant second-order interactions of candidate predictors were included in a multiple Cox proportional hazards regression model. A nomogram was generated for predicting 5-year event-free survival (EFS) probabilities.

RESULTS

The EFS and overall survival rates at 5 years were 70.9% (95% confidence interval, 68.6%-73.1%) and 81.0% (95% confidence interval, 78.9%-82.8%), respectively. The multivariable model retained five prognostic factors, including age at diagnosis interacting with tumor size, tumor primary site, Intergroup Rhabdomyosarcoma Studies clinical group, and FOXO1 fusion status. Based on each patient's total score in the nomogram, patients were stratified into four groups. The 5-year EFS rates were 94.1%, 78.4%, 65.2%, and 52.1% in the low-risk, intermediate-risk, high-risk, and very-high-risk groups, respectively, and the corresponding 5-year overall survival rates were 97.2%, 91.5%, 74.3%, and 60.8%, respectively.

CONCLUSIONS

The results presented here provide the rationale to modify the EpSSG stratification, with the most significant change represented by the replacement of histology with fusion status. This classification was adopted in the new international trial launched by the EpSSG.

Treatment of Pediatric, Adolescent, and Young Adult Patients With Fusion-Positive Alveolar Rhabdomyosarcoma Infiltrating Regional Lymph Nodes in the European CWS-2002P and RMS 2005 Studies and the Soft Tissue Sarcoma Registry

BACKGROUND

Patients with alveolar rhabdomyosarcoma (ARMS) with regional lymph node involvement (N1) are defined as "very-high-risk rhabdomyosarcoma" in Europe. Different chemotherapy regimens were used in European study protocols.

METHODS

Patients with FOXO1 fusion-positive N1 ARMS registered in the CWS-2002P study, the EpSSG RMS 2005 study, and SoTiSaR were retrospectively investigated. Patients received systemic treatment with chemotherapy (CHT) and local treatment of primary tumor (PT) and involved lymph nodes (LN) with radiotherapy (RT) and/or surgery. Kaplan-Meier estimators and Cox regression were used to examine event-free survival (EFS) and overall survival (OS) according to prognostic factors and treatment.

RESULTS

A total of 156 patients registered in RMS 2005 (n = 99), CWS-2002P (n = 20), and SoTiSaR (n = 37) between 2003 and 2020 were eligible for this analysis. Median age at diagnosis was 10.2 years [0.1-21.9]. Treatment comprised CHT with IVADo (ifosfamide, vincristine, actinomycin-D, doxorubicin, n = 93; 60%), VAIA (vincristine, actinomycin-D, ifosfamide, adriamycin/doxorubicin, n = 53; 34%) or other regimens (n = 10; 6%); resection of the PT (n = 89; 57%), LN sampling or dissection (n = 92; 59%), and/or RT (n = 139; 89%). Maintenance treatment (MT) was added in n = 99/135 (73%) patients who achieved complete remission. Five-year EFS and OS of the cohort were 45% and 47%, respectively. Age and tumor size were independent prognostic factors for EFS. Local treatment applied to the LN with surgery, RT or both significantly improved EFS (p = 0.02) and OS (p = 0.04), with no difference between the modalities (p = 0.7).

CONCLUSIONS

Patients with fusion-positive N1 ARMS carry a poor prognosis. Adequate local treatment of LN improved survival.