Dendrites possess distinct structural and functional properties that enable neurons to receive information from the environment as well as other neurons. Despite their key role in neuronal function, current understanding of the ability of neurons to regenerate dendrites is lacking. This study characterizes the structural and functional capacity for dendrite regeneration in vivo in adult animals and examines the effect of neuronal maturation on dendrite regeneration. We focused on the class IV dendritic arborization (c4da) neuron of the sensory system, which has a dendritic arbor that undergoes dramatic remodeling during the first 3 d of adult life and then maintains a relatively stable morphology thereafter. Using a laser severing paradigm, we monitored regeneration after acute and spatially restricted injury. We found that the capacity for regeneration was present in adult neurons but diminished as the animal aged. Regenerated dendrites recovered receptive function. Furthermore, we found that the regenerated dendrites show preferential alignment with the extracellular matrix (ECM). Finally, inhibition of ECM degradation by inhibition of matrix metalloproteinase 2 (Mmp2) to preserve the extracellular environment characteristics of young adults led to increased dendrite regeneration. These results demonstrate that dendrites retain regenerative potential throughout adulthood and that regenerative capacity decreases with aging.

Background A high prevalence of pulmonary embolism (PE) has been described during COVID‐19. Our aim was to identify predictive factors of PE in non‐ICU hospitalized COVID‐19 patients. Methods Data and outcomes were collected upon admission during a French multicenter retrospective study, including patients hospitalized for COVID‐19, with a CT pulmonary angiography (CTPA) performed in the emergency department for suspected PE. Predictive factors significantly associated with PE were identified through a multivariate regression model. Results A total of 88 patients (median [IQR] age of 68 years [60‐78]) were analyzed. Based on CTPA, 47 (53.4%) patients were diagnosed with PE, and 41 were not. D‐dimer ≥3000 ng/mL (OR 8.2 [95% CI] 1.3‐74.2, sensitivity (Se) 0.84, specificity (Sp) 0.78, P = .03), white blood count (WBC) ≥12.0 G/L (29.5 [2.3‐1221.2], Se 0.47, Sp 0.92, P = .02), and ferritin ≥480 µg/L (17.0 [1.7‐553.3], Se 0.96, Sp 0.44, P = .03) were independently associated with the PE diagnosis. The presence of the double criterion D‐dimer ≥3000 ng/mL and WBC ≥12.0 G/L was greatly associated with PE (OR 21.4 [4.0‐397.9], P = .004). Conclusion The white blood count, the D‐dimer and ferritin levels could be used as an indication for CTPA to confirm PE on admission in non‐ICU COVID‐19 patients.