This week in research.

Background: In Chuckwagon racing, teams of four Thoroughbreds with two lead horses in front and two wheel horses directly behind pull a 600 kg wagon around a racetrack. Our study focuses on stride parameters that have previously retrospectively predicted impending injuries. We hypothesize that in aid of the initiation of the tight figure-of-eight turn at the start of the race, the more agile lead horses gallop with higher stride frequency (SF) and reduced stride length (SL), and that differences are exacerbated in the initial accelerative race segments. Methods: Speed, SF, and SL were quantified with global navigation satellite system (GNSS) loggers over consecutive 100 m segments over 5 furlongs in sixty horses competing in Chuckwagon racing. Mixed models for SF and SL (p < 0.05, Bonferroni correction) investigated the effect of speed (fixed covariate), race segment (100 m to 1000 m), and position (lead or wheel horse) as fixed factors and their two-way interactions. Results: SF and SL were significantly affected by all two-way interactions (all p ≤ 0.025). At the average speed of 55.5 km/h, SF was 2.333 and 2.293 Hz, SL was 6.624 and 6.735 m for lead and wheel horses, respectively. Larger SF and SL differences between lead and wheel horses were found at the start and the end of the race. Conclusions: Particularly at the start and end of a Chuckwagon race, there are distinct differences in stride parameters between lead and wheel horses. Specific speed–SF–SL models for Chuckwagon lead and wheel horses might benefit from incorporating race phase.

Cutaneous leishmaniasis (CL) is the most common clinical form of leishmaniasis, characterized by persistent skin ulcers and nodules. Standard chemotherapeutic agents have substantial toxicity and do nothing to repair the damaged tissue, an unmet need that motivates the search for adjunctive strategies. Mesenchymal stem cells (MSCs) can modulate macrophage activity and support tissue regeneration, yet their role in CL has received limited attention. In this study, we tested whether bone marrow-derived MSCs (BM-MSCs) could attenuate Leishmania mexicana-induced inflammation and facilitate skin repair. Indirect co-culture of BM-MSCs with infected RAW264.7 macrophages shifted the macrophage phenotype from M1 toward M2, with higher IL-10 and Arg-1 expression and lower iNOS and IL-1β. In BALB/c mice with established CL, three weekly intravenous injections of BM-MSCs reduced paw swelling, improved skin histology, decreased type I collagen deposition, lowered Integrin β1 and Cytokeratin 17 expression, and reduced tissue parasite load. Immunofluorescence confirmed a predominantly M2 macrophage distribution in treated lesions. We inferred that BM-MSCs acted on both the immune and reparative aspects of the disease process, supporting their potential as an adjunct to conventional anti-leishmanial therapy.