Doreen Scharner

Longitudinal Cell Tracking and Simultaneous Monitoring of Tissue Regeneration after Cell Treatment of Natural Tendon Disease by Low-Field Magnetic Resonance Imaging

Treatment of tendon disease with multipotent mesenchymal stromal cells (MSC) is a promising option to improve tissue regeneration. To elucidate the mechanisms by which MSC support regeneration, longitudinal tracking of MSC labelled with superparamagnetic iron oxide (SPIO) by magnetic resonance imaging (MRI) could provide important insight. Nine equine patients suffering from tendon disease were treated with SPIO-labelled or nonlabelled allogeneic umbilical cord-derived MSC by local injection. Labelling of MSC was confirmed by microscopy and MRI. All animals were subjected to clinical, ultrasonographical, and low-field MRI examinations before and directly after MSC application as well as 2, 4, and 8 weeks after MSC application. Hypointense artefacts with characteristically low signal intensity were identified at the site of injection of SPIO-MSC in T1- and T2∗-weighted gradient echo MRI sequences. They were visible in all 7 cases treated with SPIO-MSC directly after injection, but not in the control cases treated with nonlabelled MSC. Furthermore, hypointense artefacts remained traceable within the damaged tendon tissue during the whole follow-up period in 5 out of 7 cases. Tendon healing could be monitored at the same time. Clinical and ultrasonographical findings as well as T2-weighted MRI series indicated a gradual improvement of tendon function and structure.

Stent Reconstruction of an Injured Parotid Duct in a Thoroughbred Colt

OBJECTIVE To report successful use of stent repair for a chronically injured parotid duct in a thoroughbred colt. STUDY DESIGN Clinical report. ANIMAL A 2-year-old thoroughbred colt. METHODS Chronic injury to the parotid duct was identified 4-cm caudal to the facial vessel notch on the ventral border of the right mandible. After careful surgical dissection of the surrounding firm fibrous tissue, the defect was temporarily stented using an 8-Fr human ureteral catheter (223600 ERU(®) SOFT URETERAL(®) , Laboratoires pharmaceutique, Betschdorf, France) to bridge the tissue loss. The rostral end of the catheter exited the oral cavity through a buccotomy stab incision at the level of the second premolar tooth of the maxilla. RESULTS Primary wound healing occurred and the stent was maintained for 5 weeks with saliva drainage visible when the colt was fed. After stent removal, function was restored with good cosmesis. CONCLUSIONS A tissue defect in the parotid duct can be repaired successfully by temporary use of a stent until wound healing occurs.

Retrospective Evaluation of Hemithyroidectomy in 14 Horses.

OBJECTIVE To describe the presentation, presurgical diagnostic findings, treatment, and outcome of horses with histologically confirmed, unilateral thyroid neoplasia. The complications, particularly laryngeal hemiplegia, were investigated. STUDY DESIGN Retrospective case series. ANIMALS Client-owned horses (n=14). METHODS Medical records of horses presenting with a unilateral thyroid mass due to neoplasia from 2003-2015 were reviewed. Horses must have undergone preoperative clinical evaluations that included ultrasound examination of the mass and upper airway endoscopy. Short-term follow-up at 2 weeks after surgery and owner questionnaire for long-term follow-up at >6 months were completed. RESULTS Fourteen horses aged 6-21 years were included. The majority of tumors were adenocarcinomas (11/14), mainly diagnosed in mares (9/14). Intraoperative complications included hemorrhage (1/14) and postoperative complications included seroma formation (4/14). No horse developed postoperative laryngeal hemiplegia. No horses developed clinical signs of metastases or a thyroid disorder long term (mean follow-up 4.9 years). All owners reported a successful long-term outcome. CONCLUSION The clinical findings of thyroid neoplasia in horses are not associated with the diagnosis of malignancy. Complete surgical resection of the abnormal lobe prevents local recurrence of neoplastic thyroid tissue. The modified hemithyroidectomy technique preserves the function of the recurrent laryngeal nerve.

Bovine thoracoscopy: Surgical technique and normal anatomy

Objective To describe a surgical technique for thoracoscopy and report visible anatomy within the thoracic cavity of standing cattle. Study design Prospective study. Animals Adult clinically healthy Holstein–Friesian cows (n = 15). Methods Each cow had four thoracoscopic examinations. Initially, the left hemithorax was examined after passive lung collapse, then again 24 hours later after CO2 insufflation. The right hemithorax was examined 24 hours later after passive lung collapse and again 24 hours later after CO2 insufflation. Results CO2 insufflation did not significantly improve visibility within the pleural space. Collapsed lung, aorta, esophagus, diaphragm, and azygos vein were readily viewed; however, the pericardial region was not consistently visible. Minor laceration of the lung occurred in 1 cow with adhesions, otherwise there were no intra- or postoperative complications. All cows recovered without signs of discomfort. No local swelling or emphysema occurred at the portals. Conclusions Thoracoscopy can be safely performed on healthy standing cattle.OBJECTIVE To describe a surgical technique for thoracoscopy and report visible anatomy within the thoracic cavity of standing cattle. STUDY DESIGN Prospective study. ANIMALS Adult clinically healthy Holstein-Friesian cows (n = 15). METHODS Each cow had four thoracoscopic examinations. Initially, the left hemithorax was examined after passive lung collapse, then again 24 hours later after CO2 insufflation. The right hemithorax was examined 24 hours later after passive lung collapse and again 24 hours later after CO2 insufflation. RESULTS CO2 insufflation did not significantly improve visibility within the pleural space. Collapsed lung, aorta, esophagus, diaphragm, and azygos vein were readily viewed; however, the pericardial region was not consistently visible. Minor laceration of the lung occurred in 1 cow with adhesions, otherwise there were no intra- or postoperative complications. All cows recovered without signs of discomfort. No local swelling or emphysema occurred at the portals. CONCLUSIONS Thoracoscopy can be safely performed on healthy standing cattle.

20 Cell Therapy Of Tendinopathy: Cell Tracking And Follow-up Using Magnetic Resonance Imaging

Introduction The application of multipotent mesenchymal progenitor cells is among the most promising options for treatment of tendinopathy. Studies in large animal models and equine patients suffering from natural tendinopathy suggest that these cells promote tendon regeneration and reduce re-injury rates [e.g. Crovace, 2010; Godwin, 2012]. However, the fate of the applied cells and their mechanism of action are not yet fully understood. Magnetic resonance imaging (MRI) is a standard modality for monitoring tendon healing. Moreover, MRI can be used for non-invasive cell tracking over several weeks when cells are labelled with superparamagnetic iron (SPIO) particles. However, to our knowlegde, no studies on MRI cell tracking following tendinopathy treatment have been published to date, potentially because visualisation of SPIO-labelled cells in tendons is complicated by the hypointense MRI signal of healthy tendon tissue. We aimed to overcome this difficulty by applying an imaging technique using the “magic angle effect” and to perform cell tracking and parallel monitoring of tendon healing by MRI in the equine model for the first time. Methods Initially, tendon explants were seeded with different numbers of SPIO-labelled cells in vitro and subjected to MRI and histology (n = 3). MRI was performed using low- and high-field magnets (0.27 T, 3 T and 7 T). Images were obtained in different sequences and with the tendons positioned at 90° and 54° angles to the magnetic field and cell traceability was assessed and validated. Thereafter, labelled progenitor cells were applied locally for treatment of tendon disease in 3 horses with induced tendinopathy and further 3 horses suffering from natural tendinopathy. Control tendons were injected with non-labelled cells or serum. Clinical, ultrasonographical and low-field MRI assessment was performed regularly. MRI was performed directly before and after cell application and at 2, 4, 8 and 12 weeks using T1-, T2*- and T2-weighted (w) as well as STIR sequences. Results The in vitro study demonstrated that cells are traceable in tendon tissue by low- and high-field MRI. When tendons were positioned at 54°, the magic angle effect lead to hyperintense signal from the tendon tissue, allowing to distinguish the hypointense artefacts generated by the labelled cells from the surrounding tendon. Quantitative image analysis showed good correlations between seeded cell numbers, the extent of hypointense artefacts in MRI and the extent of iron staining in histology. Still, sensitivity of cell detection strongly depended on the sequences and the field strength of the magnet used. In 0.27 T low-field MRI, which was also used for the in vivo study, T2*-w sequences obtained at 54° were most sensitive and allowed detection of 106 and 105 cells reliably, while the signal obtained from 104 cells was weak. The in vivo study confirmed that the established MRI technique is feasible for cell tracking in the living animal. Hypointense artefacts related to the applied cells could be detected at the injection site directly after injection and remained visible during the follow-up period of 12 weeks in T2*-weighted images. In 2 animals, part of the injected cells also appeared to migrate towards damaged structures in the surrounding tissue. Migration of cells to more distant locations was not evident. Furthermore, good progress in tendon regeneration could be observed in T2-w and STIR images, matching the clinical and ultrasonographical findings. Discussion The results indicate that the cells generally remain at the injection site within the damaged tendon tissue but are also capable of migration and homing to structures in the surrounding tissue. Further studies including histology will need to confirm that the hypointense artefacts in MR images correspond to the injected cells at all timepoints. References Crovace et al. Vet Med Int. 2010;2010:250978 Godwin et al. Equine Vet J. 2012;44:25–32