Thank you so much, Ruslan. I often wonder how we can improve the way we make research, publish, review and interact in science. Sadly, not everyone seems to like open discussion

Much earlier than expected, it is time for another short thread on a recent preprint at bioRxiv (Yang et al., doi.org/10.1101/2025.10.02.6…) by a group of authors led by Dr Anjali Kusumbe. Today, I want to cover some of the bioinformatics results presented in their preprint. As a reminder, based on the reanalysis of our scRNA-seq data from Koh et al. (PMID: 39537918), it is claimed in Fig. 1 and the accompanying text that lymphangiogenic markers are downregulated in aged skull samples. We now had the chance to closely examine the relevant data, which has uncovered a couple of major issues. 1/4

In a recent preprint at bioRxiv (Yang et al., doi.org/10.1101/2025.10.02.6…), a group of authors led by Dr Anjali Kusumbe challenges an article from my lab published in 2024 (Koh et al. 2024, PMID: 39537918). The new preprint refers to Extended Data Figures and Supplementary videos that are unfortunately not provided at bioRxiv. Nevertheless, the manuscript text and the 5 main figures plus a proposed model contain a couple of major issues that I will cover here. 1/

Apart from imaging, we provide an extensive set of flow cytometry data in a large (22 page) supplemental file accompanying the paper, which confirms the expansion of stromal, endothelial, total hematopoietic cells and various hematopoietic cell subsets during adulthood and aging but also in response to various challenges (such as pregnancy and stroke). 4/

Things get more interesting and controversial in Figure 3c and d. Yang et al. use tissue clearing and light sheet microscopy to show the presence of a “continuous, dense vascular network throughout the skull frontal, parietal and interparietal regions in young mice”. The CD31 immunostaining in Fig. 3a, however, shows predominantly the meningeal vasculature, easily identifiable by hallmarks such as the sagittal and transverse sinuses consisting of large diameter blood and lymphatic vessels. Periosteal vessels might be also labeled, but it is not obvious that any sinusoidal vessels of the bone marrow are stained in this sample. 9/

I want to conclude here and thank all of you who have read this thread till the end. As I have not been able to cover all issues in the preprint, I am considering another detailed thread once the Extended Data becomes public. I also hope that I have remained factual and sufficiently polite throughout my posts even though I perceive the language in the Yang et al. preprint as sometimes overly harsh and many claims unsubstantiated and wildly exaggerated. Final full disclosure: I am not only the last author of Koh et al. 2024 (PMID: 39537918) but also the former postdoctoral supervisor of the two last authors of the Yang et al. preprint. 17/17