Multiplexed mRNA analysis of brain-derived extracellular vesicles upon experimental stroke in mice reveals increased mRNA content with potential relevance to inflammation and recovery processes.

Extracellular vesicles (EVs) are lipid bilayer-enclosed structures that represent newly discovered means for cell-to-cell communication as well as promising disease biomarkers and therapeutic tools. Apart from proteins, lipids, and metabolites, EVs can deliver genetic information such as mRNA, eliciting a response in the recipient cells. In the present study, we have analyzed the mRNA content of brain-derived EVs (BDEVs) isolated 72 h after experimental stroke in mice and compared them to controls (shams) using nCounter® Nanostring panels, with or without prior RNA isolation. We found that both panels show similar results when comparing upregulated mRNAs in stroke. Notably, the highest upregulated mRNAs were related to processes of stress and immune system responses, but also to anatomical structure development, cell differentiation, and extracellular matrix organization, thus indicating that regenerative mechanisms already take place at this time-point. The five top overrepresented mRNAs in stroke mice were confirmed by RT-qPCR and, interestingly, found to be full-length. We could reveal that the majority of the mRNA cargo in BDEVs was of microglial origin and predominantly present in small BDEVs (≤ 200 nm in diameter). However, the EV population with the highest increase in the total BDEVs pool at 72 h after stroke was of oligodendrocytic origin. Our study shows that nCounter® panels are a good tool to study mRNA content in tissue-derived EVs as they can be carried out even without previous mRNA isolation, and that the mRNA cargo of BDEVs indicates a possible participation in inflammatory but also recovery processes after stroke.

Maximum Ankle Plantarflexion and Dorsiflexion Allow for Optimal Arthroscopic Access to the Talar Dome: An Anatomic 3-Dimensional Radiography Study.

PURPOSE: (1) to improve the comprehension of the topographical position of the talar dome beneath the inferior articular surface of the tibia and, (2) to illustrate the changes of possible access to the articular surface of the talar dome during arthroscopic treatment of talar osteochondral defects in an anatomical model. METHODS: Twenty matched pairs (n = 40) of anatomical ankle specimen were used. All specimens were mounted in a standardized fashion, 3-dimensional radiography was performed in 4 defined positions (maximum dorsiflexion, neutral position, noninvasive distraction, and maximum plantarflexion). All radiographs were analyzed and statistically compared. RESULTS: Anterior accessibility was highest in maximum plantarflexion (medial: 49.20 ± 9.86%, lateral: 48.19 ± 8.85%), followed by non-invasive distraction (medial: 33.60 ± 7.96%, lateral: 31.98 ± 8.30%). Neutral position (medial: 19.34 ± 6.90%, lateral: 17.54 ± 6.63%) and dorsiflexion (medial: 15.36 ± 5.03%, lateral: 13.88 ± 4.33%) were not able to significantly increase accessibility. Posterior accessibility was greatest in maximum dorsiflexion (medial: 56.69 ± 9.65%, lateral: 46.82 ± 8.36%), followed by neutral position of the ankle joint (medial: 40.95 ± 8.28%, lateral: 31.06 ± 6.92%). Noninvasive distraction (medial: 31.41 ± 8.18%, lateral: 22.99 ± 7.63%) was still significantly better than plantarflexion (medial: 14.54 ± 5.10%, lateral: 13.89 ± 3.14%) and slightly increased accessibility to the talar dome. Medially, a central area of 5.89 ± 9.76% was accessible by maximum plantarflexion and maximum dorsiflexion from anterior and posterior, respectively, laterally a central blind spot of 4.99 ± 8.61% was detected. CONCLUSIONS: From an anatomical point of view, maximum joint positions of the ankle (i.e., plantarflexion and dorsiflexion) allow for better access to the talar dome in anterior and posterior ankle arthroscopy. Noninvasive distraction may increase accessibility in anterior approaches, but has no benefit from posterior. CLINICAL RELEVANCE: This study provides insight into the morphology of the ankle joint in a standardized laboratory setup and illustrates the influence of different surgically relevant ankle joint positions. The presented data allow for better preoperative planning for the arthroscopic treatment of talar osteochondral defects.