Fibroblast-like cells isolated from peripheral blood of human, canine, guinea pig, and rat have been demonstrated to possess the capacity to differentiate into several mesenchymal lineages. The aim of this work was to investigate the possibility of isolating pluripotent precursor cells from equine peripheral blood and compare them with equine bone marrow-derived mesenchymal stem cells. Human mesenchymal stem cells (MSCs) were used as a control for cell multipotency assessment. Venous blood (n ‫؍‬ 33) and bone marrow (n ‫؍‬ 5) were obtained from adult horses. Mononuclear cells were obtained by Ficoll gradient centrifugation and cultured in monolayer, and adherent fibroblast-like cells were tested for their differentiation potential. Chondrogenic differentiation was performed in serum-free medium in pellet cultures as a threedimensional model, whereas osteogenic and adipogenic differentiation were induced in monolayer culture. Evidence for differentiation was made via biochemical, histological, and reverse transcription-polymerase chain reaction evaluations. Fibroblast-like cells were observed on day 10 in 12 out of 33 samples and were allowed to proliferate until confluence. Equine peripheral blood-derived cells had osteogenic and adipogenic differentiation capacities comparable to cells derived from bone marrow. Both cell types showed a limited capacity to produce lipid droplets compared to human MSCs. This result may be due to the assay conditions, which are established for human MSCs from bone marrow and may not be optimal for equine progenitor cells. Bone marrow-derived equine and human MSCs could be induced to develop cartilage, whereas equine peripheral blood progenitors did not show any capacity to produce cartilage at the histological level. In conclusion, equine peripheral blood-derived fibroblast-like cells can differentiate into distinct mesenchymal lineages but have less multipotency than bone marrow-derived MSCs under the conditions used in this study.

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Background: Equine palmar foot syndrome is a common cause of chronic lameness. Radiographic and ultrasound imaging are sometimes insufficient to examine the podotrochlear apparatus. MRI and CT have great diagnostic value but are expensive and are not available for all patients. Bursography might become a highly available and inexpensive diagnostic tool for this purpose.Material and Methods: To evaluate the technique, standard palmaroproximal-palmarodistal-oblique (PaPr-PaDiO ) and dorsoproximal-palmarodistal oblique (DPr-PaDiO) radiographs were acquired both before and after injecting contrast medium in the navicular bursa (NB) and were subsequently compared with gross pathology as gold standard in 48 dissected front feet. For all results a scoring system with 4 groups was introduced. Results: Compared with the gold standard, the fleiss kappa between groups were 0.349, 0.280, 0.358, and 0.455 for DPr-PaDiO, PaPr-PaDiO, DPr-PaDiO contrast enhanced (CE), and PaPr-PaDiO (CE), respectively (P < 0.001). The combined view of native images and the view of all pictures were correlated to the gold standard with a Spearman’s rank correlation coefficient of 0.373 and 0.556, respectively (P < 0.001). The Kruskal-Wallis-Test did not reveal any significant difference between standard radiographs and gross pathology group 1, 2, and 3. Contrast enhanced (CE) radiographs showed significant differences between gross pathology group 1 versus 2 and 3. Group 4 feet (gross pathology score) were remarkably well evaluated by both radiographic imaging techniques. When more than two projections were graded with findings, the respective feet were found to be moderately to severely changed in gross pathology (specificity: 100 %, sensitivity: 41.4 %). 3/13 (23.1%) group 3 and 4/19 (21.1%) group 4 specimens showed altered CE radiographs and unremarkable native radiographs. 2/13 (15.4%) group 3 and 2/19 (10.5%) group 4 feet do not have any findings in radiographs. Conclusion: In the present study, bursography with two additional CE images led to more information on the podotrochlear apparatus compared to native radiographs alone. Some cases with no changes in native radiographs will be detected in bursography, and in specimens with altered native radiographs, the diagnosis will be ensured. Therefore, bursography is a useful tool for diagnosing horses with suspected navicular disease when an MRI is not possible or the NB is injected anyway for therapeutic purposes.