Differential development and electrophysiological activity in cultured cortical neurons from the mouse and cynomolgus monkey.

In vitro cultures of primary cortical neurons are widely used to investigate neuronal function. However, it has yet to be fully investigated whether there are significant differences in development and function between cultured rodent and primate cortical neurons, and whether these differences influence the utilization of cultured cortical neurons to model pathological conditions. Using in vitro culture techniques combined with immunofluorescence and electrophysiological methods, our study found that the development and maturation of primary cerebral cortical neurons from cynomolgus monkeys were slower than those from mice. We used a microelectrode array technique to compare the electrophysiological differences in cortical neurons, and found that primary cortical neurons from the mouse brain began to show electrical activity earlier than those from the cynomolgus monkey. Although cultured monkey cortical neurons developed slowly in vitro, they exhibited typical pathological features-revealed by immunofluorescent staining-when infected with adeno-associated viral vectors expressing mutant huntingtin (HTT), the Huntington's disease protein. A quantitative analysis of the cultured monkey cortical neurons also confirmed that mutant HTT significantly reduced the length of neurites. Therefore, compared with the primary cortical neurons of mice, cultured monkey cortical neurons have longer developmental and survival times and greater sustained physiological activity, such as electrophysiological activity. Our findings also suggest that primary cynomolgus monkey neurons cultured in vitro can simulate a cell model of human neurodegenerative disease, and may be useful for investigating time-dependent neuronal death as well as treatment via neuronal regeneration. All mouse experiments and protocols were approved by the Animal Care and Use Committee of Jinan University of China (IACUC Approval No. 20200512-04) on May 12, 2020. All monkey experiments were approved by the IACUC protocol (IACUC Approval No. LDACU 20190820-01) on August 23, 2019 for animal management and use.

Tracking and Predicting COVID-19 Epidemic in China Mainland

By proposing a varying coefficient Susceptible-Infected-Removal model (vSIR), we track the epidemic of COVID-19 in 30 provinces in China and 15 cities in Hubei province, the epicenter of the outbreak. It is found that the spread of COVID-19 has been significantly slowing down within the two weeks from January 27 to February 10th with 87.0% and 84.3% reductions in the reproduction number R0 among the 30 provinces and 15 Hubei cities, respectively. This suggests the extreme control measures implemented since January 23, which include cutting off Wuhan and many other cities and towns, a great public awareness and high level of self isolation at home, have contributed to a substantial decline in the reproductivity of the COVID-19 in China. We predict that Hubei province will reach its peak between February 20 and 22, 2020, and if the removal rate can be increased to 0.1, the epidemic outside Hubei province will end in May 2020, and inside Hubei in early June.