Adult Human Neurogenesis: From Microscopy to Magnetic Resonance Imaging

Neural stem cells reside in well-defined areas of the adult human brain and are capable of generating new neurons throughout the life span. In rodents, it is well established that the new born neurons are involved in olfaction as well as in certain forms of memory and learning. In humans, the functional relevance of adult human neurogenesis is being investigated, in particular its implication in the etiopathology of a variety of brain disorders. Adult neurogenesis in the human brain was discovered by utilizing methodologies directly imported from the rodent research, such as immunohistological detection of proliferation and cell-type specific biomarkers in postmortem or biopsy tissue. However, in the vast majority of cases, these methods do not support longitudinal studies; thus, the capacity of the putative stem cells to form new neurons under different disease conditions cannot be tested. More recently, new technologies have been specifically developed for the detection and quantification of neural stem cells in the living human brain. These technologies rely on the use of magnetic resonance imaging, available in hospitals worldwide. Although they require further validation in rodents and primates, these new methods hold the potential to test the contribution of adult human neurogenesis to brain function in both health and disease. This review reports on the current knowledge on adult human neurogenesis. We first review the different methods available to assess human neurogenesis, both ex vivo and in vivo and then appraise the changes of adult neurogenesis in human diseases

Perspective: Of mice and men - How widespreads adult neurogenesis?

These are exciting times for research on adult hippocampal neurogenesis (AHN). Debate and controversy regarding the existence of generation of new neurons in the adult, and even diseased human brain flourishes as articles against and in favor accumulate. Adult neurogenesis in the human brain is a phenomenon that does not share the qualities of quantum mechanics. The scientific community should agree that human AHN exists or does not, but not both at the same time. In this commentary, we discuss the latest research articles about hAHN and what their findings imply for the neurogenesis field

Quiescent adult neural stem cells are exceptionally sensitive to cosmic radiation

Generation of new neurons in the adult brain, a process that is likely to be essential for learning, memory, and mood regulation, is impaired by radiation. Therefore, radiation exposure might have not only such previously expected consequences as increased probability of developing cancer, but might also impair cognitive function and emotional stability. Radiation exposure is encountered in settings ranging from cancer therapy to space travel; evaluating the neurogenic risks of radiation requires identifying the at-risk populations of stem and progenitor cells in the adult brain. Here we have used a novel reporter mouse line to find that early neural progenitors are selectively affected by conditions simulating the space radiation environment. This is reflected both in a decrease in the number of these progenitors in the neurogenic regions and in an increase in the number of dying cells in these regions. Unexpectedly, we found that quiescent neural stem cells, rather than their rapidly dividing progeny, are most sensitive to radiation. Since these stem cells are responsible for adult neurogenesis, their death would have a profound impact on the production of new neurons in the irradiated adult brain. Our finding raises an important concern about cognitive and emotional risks associated with radiation exposure

Damage-responsive neuro-glial clusters coordinate the recruitment of dormant neural stem cells in Drosophila.

Recruitment of stem cells is crucial for tissue repair. Although stem cell niches can provide important signals, little is known about mechanisms that coordinate the engagement of disseminated stem cells across an injured tissue. In Drosophila, adult brain lesions trigger local recruitment of scattered dormant neural stem cells suggesting a mechanism for creating a transient stem cell activation zone. Here, we find that injury triggers a coordinated response in neuro-glial clusters that promotes the spread of a neuron-derived stem cell factor via glial secretion of the lipocalin-like transporter Swim. Strikingly, swim is induced in a Hif1-α-dependent manner in response to brain hypoxia. Mammalian Swim (Lcn7) is also upregulated in glia of the mouse hippocampus upon brain injury. Our results identify a central role of neuro-glial clusters in promoting neural stem cell activation at a distance, suggesting a conserved function of the HIF1-α/Swim/Wnt module in connecting injury-sensing and regenerative outcomes

Space Exploration: A Risk for Neural Stem Cells

During spaceflights beyond low Earth orbit, astronauts are exposed to potentially carcinogenic and tissue damaging galactic cosmic rays, solar proton events, and secondary radiation that includes neutrons and recoil nuclei produced by nuclear reactions in spacecraft walls or in tissue (1). Such radiation risk may present a significant health risk for human exploration of the moon and Mars. Emerging evidence that generation of new neurons in the adult brain may be essential for learning, memory, and mood (2) and that radiation is deleterious to neurogenesis (3-5) underscores a previously unappreciated possible risk to the cognitive functions and emotional stability of astronauts exposed to radiation in space. Here we use a novel reporter mouse line to identify at-risk populations of stem and progenitor cells in the brain and find, unexpectedly, that quiescent stem-like cells (rather than their rapidly dividing progeny) in the hippocampus constitute the most vulnerable cell population. This finding raises concerns about the possible risks facing astronauts on long duration space missions

Perfil del cuidador de adulto mayor en situación de pandemia por SARS-COV-2, Lima-Perú

Objetive: To know the profile of the older adult caregiver in a SARS-COV-2 pandemic, Lima-Peru. Materials and methods: observational and cross-sectional study; population made up of 92 caregivers of older adults, non-relatives and who receive remuneration, both sexes, over 18 years of age, voluntary participation; older adults residing in districts of northern Lima, economic stratum C and D. Sociodemographic variables, education / training, vaccines, self-confidence or self-safety, and degree of anxiety or stress were evaluated in the caregiver; the older adult variables included were sociodemographic, vaccines, disabilities and disease. Questionnaire was completed virtually during the last week of March 2020. Results: caregiver profile, mean age 33.48 years, 95.7% female, 77.2% do not have training in hand washing, 96.7% without training in stress management in older adults. Self-confidence or self-confidence in caring for the elderly was 1.97 (scale from 0 to 5) and the degree of anxiety or stress during care 8.03 (scale from 0 to 10). Conclusions: deficiencies in the profile of the caregiver who oversees the elderly are evident, the development of strategies to reverse the problem is urgent, the prioritization of actions for the care of the elderly as a vulnerable person are urgent. Strategies should include caregiver training, stress self-management, and access to home care services, among others.Objetivo: Conocer el perfil del cuidador de adulto mayor en situación de pandemia por SARS-COV-2, Lima-Perú. Materiales y métodos: estudio observacional y transversal; población conformada por 92 cuidadores de adulto mayor, no familiares y que reciben remuneración, ambos sexos, mayores de 18 años, participación voluntaria; adultos mayores residentes en distritos de Lima norte, estrato económico C y D. Se evaluó en el cuidador variables sociodemográficas, formación/capacitación, vacunas, autoconfianza o autoseguridad y grado de angustia o estrés; las variables del adulto mayor fueron las sociodemográficas, vacunas, discapacidades y enfermedad. Se completó cuestionario de forma virtual durante la última semana de marzo de 2020. Resultados: perfil del cuidador, edad media 33,48 años, 95,7% sexo femenino, 77,2% no tienen capacitación en lavado de manos, 96,7% sin capacitación en el manejo de estrés en adulto mayor. La autoconfianza o autoseguridad para con el cuidado del adulto mayor fue 1,97 (escala de 0 a 5) y el grado de angustia o estrés durante el cuidado 8,03 (escala de 0 a 10). Conclusiones: se evidencia deficiencias en el perfil del cuidador que tiene a su cargo al adulto mayor, se hace urgente el desarrollo de estrategias para revertir el problema, la priorización de acciones para el cuidado del adulto mayor como persona vulnerable son urgentes. Las estrategias deben incluir capacitación del cuidador, automanejo de estrés y acceso a servicios de atención domiciliaria entre otras

Characteristics and outcomes of adult patients in the PETHEMA registry with relapsed or refractory FLT3-ITD mutation-positive acute myeloid leukemia

This retrospective study investigated outcomes of 404 patients with relapsed/refractory (R/R) FMS-like tyrosine kinase 3 (FLT3)-internal tandem duplication (ITD) acute myeloid leukemia (AML) enrolled in the PETHEMA registry, pre-approval of tyrosine kinase inhibitors. Most patients (63%) had received first-line intensive therapy with 3 + 7. Subsequently, patients received salvage with intensive therapy (n = 261), non-intensive therapy (n = 63) or supportive care only (n = 80). Active salvage therapy (i.e., intensive or non-intensive therapy) resulted in a complete remission (CR) or CR without hematological recovery (CRi) rate of 42%. More patients achieved a CR/CRi with intensive (48%) compared with non-intensive (19%) salvage therapy (p < 0.001). In the overall population, median overall survival (OS) was 5.5 months; 1- and 5-year OS rates were 25% and 7%. OS was significantly (p < 0.001) prolonged with intensive or non-intensive salvage therapy compared with supportive therapy, and in those achieving CR/CRi versus no responders. Of 280 evaluable patients, 61 (22%) had an allogeneic stem-cell transplant after they had achieved CR/CRi. In conclusion, in this large cohort study, salvage treatment approaches for patients with FLT3-ITD mutated R/R AML were heterogeneous. Median OS was poor with both non-intensive and intensive salvage therapy, with best long-term outcomes obtained in patients who achieved CR/CRi and subsequently underwent allogeneic stem-cell transplant.This study was supported by Centro de Investigación Biomédica en Red Cáncer (CIBERONC), Valencia, Spain [CB16/12/00284]

Impact of measurable residual disease by decentralized flow cytometry: a PETHEMA real-world study in 1076 patients with acute myeloid leukemia

The role of decentralized assessment of measurable residual disease (MRD) for risk stratification in acute myeloid leukemia (AML) remains largely unknown, and so it does which methodological aspects are critical to empower the evaluation of MRD with prognostic significance, particularly if using multiparameter flow cytometry (MFC). We analyzed 1076 AML patients in first remission after induction chemotherapy, in whom MRD was evaluated by MFC in local laboratories of 60 Hospitals participating in the PETHEMA registry. We also conducted a survey on technical aspects of MRD testing to determine the impact of methodological heterogeneity in the prognostic value of MFC. Our results confirmed the recommended cutoff of 0.1% to discriminate patients with significantly different cumulative-incidence of relapse (-CIR- HR:0.71, P < 0.001) and overall survival (HR: 0.73, P = 0.001), but uncovered the limited prognostic value of MFC based MRD in multivariate and recursive partitioning models including other clinical, genetic and treatment related factors. Virtually all aspects related with methodological, interpretation, and reporting of MFC based MRD testing impacted in its ability to discriminate patients with different CIR. Thus, this study demonstrated that “real-world” assessment of MRD using MFC is prognostic in patients at first remission, and urges greater standardization for improved risk-stratification toward clinical decisions in AML.This study was supported by the Centro de Investigación Biomédica en Red – Área de Oncología - del Instituto de Salud Carlos III (CIBERONC; CB16/12/00369, CB16/12/00233, CB16/12/00284 and CB16/12/00400), Instituto de Salud Carlos III/Subdirección General de Investigación Sanitaria (FIS No. PI16/01661, PI16/00517 and PI18/01946), Gerencia Regional de Salud de CyL (GRS 1346/A/16) and the Plan de Investigación de la Universidad de Navarra (PIUNA 2014-18). This study was supported internationally by the Cancer Research UK, FCAECC and AIRC under the Accelerator Award Program EDITOR

Early myeloma-related death in elderly patients: development of a clinical prognostic score and evaluation of response sustainability role

Although survival of elderly myeloma patients has significantly improved there is still a subset of patients who, despite being fit and achieving optimal responses, will die within 2 years of diagnosis due to myeloma progression. The objective of this study was to define a scoring prognostic index to identify this group of patients. We have evaluated the outcome of 490 newly diagnosed elderly myeloma patients included in two Spanish trials (GEM2005-GEM2010). Sixty-eight patients (13.8%) died within 2 years of diagnosis (early deaths) due to myeloma progression. Our study shows that the use of simple scoring model based on 4 widely available markers (elevated LDH, ISS 3, high risk CA or >75 years) can contribute to identify up-front these patients. Moreover, unsustained response (<6 months duration) emerged as one important predictor of early myeloma-related mortality associated with a significant increase in the risk of death related to myeloma progression. The identification of these patients at high risk of early death is relevant for innovative trials aiming to maintain the depth of first response, since many of them will not receive subsequent lines of therapy.This study was supported by the Cooperative Research Thematic Networkgrants RD12/0036/0058 and RD12/0036/0046 of the Redde Cancer (Cancer Network of Excellence); Instituto deSalud Carlos III, Spain, Instituto de Salud Carlos III/SubdirecciónGeneral de Investigación Sanitaria part-financedby the European Regional Development Fund (FIS: PI12/01761; PI12/02311; PI13/01469; PI14/01867, G03/136;Sara Borrell: CD13/00340); Asociación Española Contra el Cáncer (GCB120981SAN) and FEDER