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The SARS-CoV-2 pandemic has strained health systems worldwide, and infection numbers continue to rise. While previous data have already shown that many patients suffer from symptoms for months after an acute infection, data on risk factors and long-term outcomes are incomplete, particularly for the working population.We aimed to provide information on the prevalence of post-COVID-19 conditions in a subset of the German working-age population (18-61 years old) and to analyze risk factors.We conducted an online survey with a health questionnaire among registered potential stem cell donors with or without a self-reported history of polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection. Logistic regression models were used to examine the risks of severity of acute infection, sex, age, body mass index, diabetes mellitus, and arterial hypertension medication on post-COVID-19 symptoms.A total of 199,377 donors reported evaluable survey questionnaires-12,609 cases had a history of SARS-CoV-2 infection and 186,768 controls had none. Overall, cases reported physical, cognitive, and psychological complaints more frequently compared to controls. Increased rates of complaints persisted throughout 15 months postinfection, for example, 28.4%/19.3% of cases/controls reported fatigue (p 0.0001) and 9.5%/3.6% of cases/controls reported loss of concentration (p 0.0001). No significant differences were observed in the frequency of reported symptoms between 3 and 15 months postinfection. Multivariate analysis revealed a strong influence of the severity of the acute SARS-CoV-2 infection episode and age on the risk for post-COVID-19 conditions.We report the prevalence of post-COVID-19 conditions in mainly unvaccinated individuals with SARS-CoV-2 infections between February 2020 and August 2021. The severity of the acute course and age were major risk factors. Vaccinations may reduce the risk of post-COVID-19 conditions by reducing the risk of severe infections.

Many stem cell donor registries determine the cytomegalovirus (CMV) IgG serostatus at donor recruitment as it is an important marker for donor selection in the context of hematopoietic stem cell transplantation. To make sample collection less uncomfortable for the donor, we have developed a method that allows CMV status determination from buccal swab samples, thus avoiding blood drawing. However, the determination fails in some cases which leads to new donors being listed for donor search without CMV status, thus hindering donor searches. In this work, we evaluated the success rate of repeating CMV status analysis from a new swab. Our results show that about 90% of the samples could be successfully determined. Due to the great importance of the CMV status in donor search, we consider the retesting approach to be highly recommended for stem cell donor registries.

Objectives To determine the impact of the 32bp deletion (CCR5Δ32) in the coding region of the C-C chemokine receptor 5 (CCR5) on the risk of contracting SARS-CoV-2 and severe COVID-19. Methods Cross-sectional study among stem cell donors registered with DKMS in Germany. Genetic information was linked to self-reported COVID-19 outcome data. Multivariable regression models were fitted to determine the risk of contracting SARS-CoV-2, severe respiratory tract infection (RTI) and respiratory hospitalization. Results CCR5 information was available for 110,544 donors who were tested at least once for SARS-CoV-2. 5,536 participants with CCR5 information reported SARS-CoV-2 infections. For 4,758 donors the COVID-19 disease course was fully evaluable, 498 reported no symptoms, 1,227 described symptoms of severe respiratory tract infections, and 164 of these individuals required respiratory hospitalization. The distribution of CCR5Δ32 genotypes (homozygous wild-type vs. CCR5Δ32 present) did not differ significantly between individuals with or without SARS-CoV-2 infections (OR 0.96, 95%-CI 0.89-1.03, p = 0.21) nor between individuals with or without symptomatic infections (OR 1.13, 95%-CI 0.88-1.45, p = 0.32), severe RTI (OR 1.03, 955-CI 0.88-1.22, p = 0.68) or respiratory hospitalizations (OR 1.16, 95%-CI 0.79-1.69, p = 0.45). Conclusions Our data implicate that CCR5Δ32 mutations do not determine the risk of SARS-CoV-2 infections nor the disease course. Trial registration We registered the study with the German Center for Infection Research ( https://dzif.clinicalsite.org/de/cat/2099/trial/4361 ).

The COVID-19 pandemic has serious implications also for patients with other diseases. Here, we describe the effects of the pandemic on unrelated hematopoietic stem cell donation and transplantation from the perspective of DKMS, a large international donor registry. Especially, we cover the development of PBSC and bone marrow collection figures, donor management including Health and Availability Check (HAC), transport and cryopreservation of stem cell products, donor recruitment and business continuity measures. The total number of stem cell products provided declined by around 15% during the crisis with a particularly strong decrease in bone marrow products. We modified donor management processes to ensure donor and product safety. HAC instead of confirmatory typing was helpful especially in countries with strict lockdowns. New transport modes were developed so that stem cell products could be safely delivered despite COVID-19-related travel restrictions. Cryopreservation of stem cell products became the new temporary standard during the pandemic to minimize risks related to transport logistics and donor availability. However, many products from unrelated donors will never be transfused. DKMS discontinued public offline donor recruitment, leading to a 40% decline in new donors during the crisis. Most DKMS employees worked from home to ensure business continuity during the crisis.

BackgroundWith increasing rates of SARS-CoV-2 infections and the intention to avoid a lock-down, the risks for the working population are of great interest. No large studies have been conducted which allow risk assessment for this population.MethodsDKMS is a non-profit donor center for stem cell donation and reaches out to registered volunteers between 18 and 61 years of age. To identify risk factors for severe COVID-19 courses in this population we performed a cross-sectional study. Self-reported data on oro- or nasopharyngeal swabs, risk factors, symptoms and treatment were collected with a health questionnaire and linked to existing genetic data. We fitted multivariable logistic regression models for the risk of contracting SARS-CoV-2, risk of severe respiratory infection and risk of hospitalization.FindingsOf 4,440,895 contacted volunteers 924,660 (20.8%) participated in the study. Among 157,544 participants tested, 7,948 reported SARS-CoV-2 detection. Of those, 947 participants (11.9%) reported an asymptomatic course, 5,014 (63.1%) mild/moderate respiratory infections, and 1,987 (25%) severe respiratory tract infections. In total, 286 participants (3.6%) were hospitalized for respiratory tract infections. The risk of hospitalization in comparison to a 20-year old person of normal weight was 2.1-fold higher (95%-CI, 1.2-3.69, p=0.01) for a person of same age with a BMI between 35-40 kg/m2, it was 5.33-fold higher (95%-CI, 2.92-9.70, p2. Blood group A was associated with a 1.15-fold higher risk for contracting SARS-CoV-2 (95%-CI 1.08-1.22, pInterpretationIn this relatively healthy population, the risk for hospitalizations due to SARS-CoV-2 infections was moderate. Age and BMI were major risk factors. These data may help to tailor risk-stratified preventive measures.FundingDKMS initiated and conducted this study. The Federal Ministry of Education and Research (BMBF) supported the study by a research grant (COVID-19 call (202), reference number 01KI20177).

Cellular plasticity at the structural level and sleep at the behavioural level are both essential for memory formation. The link between the two is not well understood. A functional connection between adult neurogenesis and hippocampus-dependent memory consolidation during NREM sleep has been hypothesized but not experimentally shown. Here, we present evidence that during a three-day learning session in the Morris water maze task a genetic knockout model of adult neurogenesis (Cyclin D2−/−) showed changes in sleep macro- and microstructure. Sleep EEG analyses revealed a lower total sleep time and NREM fraction in Cyclin D2−/− mice as well as an impairment of sleep specific neuronal oscillations that are associated with memory consolidation. Better performance in the memory task was associated with specific sleep parameters in wild-type, but not in Cyclin D2−/− mice. In wild-type animals the number of proliferating cells correlated with the amount of NREM sleep. The lack of adult neurogenesis led to changes in sleep architecture and oscillations that represent the dialog between hippocampus and neocortex during sleep. We suggest that adult neurogenesis—as a key event of hippocampal plasticity—might play an important role for sleep-dependent memory consolidation and modulates learning-induced changes of sleep macro- and microstructure.

We estimated HLA allele and haplotype frequencies of the Saudi Arabian population from a sample of 45,457 registered stem cell donors. The most frequent HLA alleles were A*02:01g (18.5%), C*06:02g (16.1%), B*51:01g (14.1%), DRB1*07:01g (16.2%), DQB1*02:01g (30.5%), and DPB1*04:01g (33.6%). The most frequent 5-locus haplotypes were A*02:05g~C*06:02g~B*50:01g~DRB1*07:01g~DQB1*02:01g (1.73%), A*02:01g~C*06:02g~B*50:01g~DRB1*07:01g~DQB1*02:01g (1.66%), and A*26:01g~C*07:02g~B*08:01g~DRB1*03:01g~DQB1*02:01g (1.38%). Furthermore, we used the calculated haplotype frequencies to estimate stem cell donor matching probabilities for Saudi Arabian donor and patient populations under various matching requirements. These results are relevant for strategic donor registry planning in the Kingdom of Saudi Arabia.

Understanding mechanisms mediating tumor metastasis is crucial for diagnostic and therapeutic targeting. Here, we take advantage of a transparent embryonic zebrafish xenograft model (eZXM) to visualize and track metastatic cells in real time using selective plane illumination microscopy (SPIM) for up to 30 h. Injected human leukemic and breast cancer cells exhibited cell-type specific patterns of intravascular distribution with leukemic cells moving faster than breast cancer cells. Tracking of tumor cells from high-resolution images revealed acute differences in intravascular speed and distance covered by cells. While the majority of injected breast cancer cells predominantly adhered to nearby vasculature, about 30% invaded the non-vascularized tissue, reminiscent of their metastatic phenotype. Survival of the injected tumor cells appeared to be partially inhibited and time-lapse imaging showed a possible role for host macrophages of the recipient embryos. Leukemic cell dissemination could be effectively blocked by pharmacological ROCK1 inhibition using Fasudil. These observations, and the ability to image several embryos simultaneously, support the use of eZXM and SPIM imaging as a functional screening platform to identify compounds that suppress cancer cell spread and invasion.

Introduction: World Marrow Donor Association (WMDA) promotes global collaboration for the benefit of stem cell donors and transplant patients. WMDA activities include recording the number of unrelated hematopoietic stem cell (HSC) donations globally. Because the COVID-19 pandemic also has an impact on the treatment of patients with other diseases, we hypothesise that it also impacted the practice of unrelated hematopoietic stem cell transplantation (HSCT). We used the 2020 WMDA data to examine the trends in unrelated HSC donations during the COVID-19 pandemic globally, per continent and per country/region. Methods: Donor registries (DRs) and cord blood banks (CBBs) from 61 countries participated in the 2020 survey, compared to 59 countries in the 2019. Slight differences in participation between the data sets of 2019 and 2020 do not explain the trends we observe in HSC donations. Country/region-specific COVID-19 data on cases and deaths were obtained from the data repository operated by the Johns Hopkins University Center for Systems Science and Engineering(https://github.com/CSSEGISandData/COVID-19, accessed July 12, 2021); and population data were retrieved from the Worldometer website(https://www.worldometers.info/, accessed July 12, 2021). Results: HSC donations from unrelated donors (peripheral blood stem cells (PBSC) and bone marrow (BM)) decreased from 20,330 in 2019 to 19,623 in 2020 (-3.5%), compared to an average annual growth rate of 3.9% from 2015 to 2019 (figure 1). The 3.5% decrease is composed of a 29.0% decrease for BM and a 2.6% increase for PBSC, resulting in a drop in the BM share of unrelated HSC donations from 19.3% in 2019 to 14.2% in 2020. The number of cord blood unit (CBU) shipments globally decreased with 3.5% from 2,851 to 2,750. The percentage of national use of HSC products (PBSC and BM) increased from 51.2% to 53.5%. When considering the continent on which the patient is transplanted (table 1), the change rate of use of HSC donated products in 2020 vs. 2019 ranged from -28.0% in South America to +18.2% in Africa. In absolute numbers, the largest decrease of HSC donations occurred for patients in Asia (n=-485) followed by Europe (n=-205), and the largest increase occurred in North America (n=+88) followed by Oceania (n=+25). The share of HSC donations requiring intercontinental transport decreased from 24.6% in 2019 to 21.9% in 2020. In terms of the country/region of transplant (table 2), the largest percentage decrease occurred in Colombia (-90,5%) followed by Russia (-55,5%). In absolute numbers, the largest decrease occurred in Turkey (-147), with Japan following (-128, although Japan saw an increase of CBU use of +106). The highest growth rate was observed in Iran (+28,7%), followed by South Africa (+28,2%). In absolute figures, the greatest increase occurred in Italy (+67). The two countries receiving the largest HSC donation numbers showed no major changes versus the previous year: USA: +0.6% (although a decrease for CBU of -21,0% was observed) and Germany: -2.4%. We did not find any significant correlation between the numbers of COVID-19 cases or COVID-19-related deaths per 1 million inhabitants with the HSC donation numbers (Spearman's r=0.05 for cases and =0.08 for deaths). Discussion: The decline in the number of unrelated HSC donations in 2020 suggests an impact of the COVID-19 pandemic on HSC donation and unrelated HSCT. The significant decrease in BM collections and intercontinental/cross-border shipments can be explained by logistically complex processes, as well the increased risk to the donor of being exposed to an operative procedure. CBU as a stem cell source potentially circumvents these logistical complications. However, on a global scale our data does not show increased use of CBU suggesting that decisions to use CBU as a stem cell source did not change in the pandemic . We were unable to demonstrate a correlation between country/region-specific severity of the pandemic and HSC donation numbers. We suspect this is due to the data quality of reported number of COVID-19 cases and COVID-19-related deaths. Also, we did not gather monthly data and therefore could not specify pandemic waves. In conclusion, we would like to point out the fact that global exchanges of HSC products continued and only decreased slightly is an extraordinary achievement of DRs, CBBs and their donors and is a testament to the importance of international collaborations in the WMDA. Figure 1 Figure 1. Disclosures Devine: Orca Bio: Consultancy, Research Funding; Johnsonand Johnson: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; Magenta Therapeutics: Current Employment, Research Funding; Tmunity: Current Employment, Research Funding; Vor Bio: Research Funding; Kiadis: Consultancy, Research Funding; Be the Match: Current Employment. Shaw: Orca bio: Consultancy; mallinkrodt: Other: payments. Forman: Mustang Bio: Consultancy, Current holder of individual stocks in a privately-held company; Lixte Biotechnology: Consultancy, Current holder of individual stocks in a privately-held company; Allogene: Consultancy.

Physical exercise has well-established anti-inflammatory effects, with neuro-immunological crosstalk being proposed as a mechanism underlying the beneficial effects of exercise on brain health. Here, we used physical exercise, a strong positive modulator of adult hippocampal neurogenesis, as a model to identify immune molecules that are secreted into the blood stream, which could potentially mediate this process. Proteomic profiling of mouse plasma showed that levels of the chemokine lymphotactin (XCL1) were elevated after four days of running. We found that XCL1 treatment of primary cells isolated from both the dentate gyrus and the subventricular zone of the adult mice led to an increase in the number of neurospheres and neuronal differentiation in neurospheres derived from the dentate gyrus. In contrast, primary dentate gyrus cells isolated from XCL1 knockout mice formed fewer neurospheres and exhibited a reduced neuronal differentiation potential. XCL1 supplementation in a dentate gyrus-derived neural precursor cell line promoted neuronal differentiation and resulted in lower cell motility and a reduced number of cells in the S phase of the cell cycle. This work suggests an additional function of the chemokine XCL1 in the brain and underpins the complexity of neuro-immune interactions that contribute to the regulation of adult hippocampal neurogenesis.

Mechanisms mediating tumor metastasis are crucial for diagnostic and therapeutic targeting. Here, we take advantage of a transparent embryonic zebrafish xenograft model (eZXM) to visualize and track injected human leukemic and breast cancer cells in real time using selective plane illumination microscopy (SPIM) for up to 30 hours. Injected cells exhibited disease-specific patterns of intravascular distribution with leukemic cells moving faster than breast cancer cells. While breast cancer cells predominantly adhered to nearby regions, about 30% invaded the avascularized tissue, reminiscent of their metastatic phenotype. Survival of the injected tumor cells was partly inhibited by the cellular innate immune system of the recipient embryos and leukemic cell dissemination was effectively inhibited by pharmacological ROCK1 blockade. These observations, and the ability to image several embryos simultaneously, support the use of eZXM and SPIM imaging as a functional screening platform to identify compounds that restricts cancer cell spread and invasion.

There are two neurogenic niches in the adult mammalian brain: the subventricular zone of the lateral ventricle and the subgranular zone of the hippocampal dentate gyrus. Cells from these areas can be isolated and maintained in vitro, using two different culture systems to assess their potential regarding proliferation and differentiation in a reductionist model. While the neurosphere assay is primarily performed to directly study the proliferative and differentiation potential of cells in individual brains, the monolayer culture allows single cell analysis in a rather homogeneous cell population. Here, we describe the isolation, culturing methods and differentiation of neural precursor cells in both systems.