Z. Adamiak

MR monitoring of minimally invasive delivery of mesenchymal stem cells into the porcine intervertebral disc.

Purpose Bone marrow stem cell therapy is a new, attractive therapeutic approach for treatment of intervertebral disc (IVD) degeneration; however, leakage and backflow of transplanted cells into the structures surrounding the disc may lead to the formation of undesirable osteophytes. The purpose of this study was to develop a technique for minimally invasive and accurate delivery of stem cells. Methods Porcine mesenchymal stem cells (MSCs) were labeled with superparamagnetic iron oxide nanoparticles (SPIO, Molday ION rhodamine) and first injected into the explanted swine lumbar IVD, followed by ex vivo 3T MRI. After having determined sufficient sensitivity, IVD degeneration was then induced in swine (n=3) by laser-evaporation. 3 x 106 SPIO-labeled cells embedded within hydrogel were injected in 2 doses using a transcutaneous cannula and an epidural anesthesia catheter. T2-weighted MR images were obtained at 3T before and immediately after cell infusion. Two weeks after injection, histological examination was performed for detection of transplanted cells. Results MSCs were efficiently labeled with Molday ION rhodamine. Cells could be readily detected in the injected vertebral tissue explants as distinct hypointensities with sufficient sensitivity. MR monitoring indicated that the MSCs were successfully delivered into the IVD in vivo, which was confirmed by iron-positive Prussian Blue staining of the tissue within the IVD. Conclusion We have developed a technique for non-invasive monitoring of minimally invasive stem delivery into the IVD at 3T. By using a large animal model mimicking the anatomy of IVD in humans, the present results indicate that this procedure may be clinically feasible.

Real-time MRI for precise and predictable intra-arterial stem cell delivery to the central nervous system

Stem cell therapy for neurological disorders reached a pivotal point when the efficacy of several cell types was demonstrated in small animal models. Translation of stem cell therapy is contingent upon overcoming the challenge of effective cell delivery to the human brain, which has a volume ∼1000 times larger than that of the mouse. Intra-arterial injection can achieve a broad, global, but also on-demand spatially targeted biodistribution; however, its utility has been limited by unpredictable cell destination and homing as dictated by the vascular territory, as well as by safety concerns. We show here that high-speed MRI can be used to visualize the intravascular distribution of a superparamagnetic iron oxide contrast agent and can thus be used to accurately predict the distribution of intra-arterial administered stem cells. Moreover, high-speed MRI enables the real-time visualization of cell homing, providing the opportunity for immediate intervention in the case of undesired biodistribution.

Distribution and chemical coding of sensory neurons innervating the skin of the porcine hindlimb

The aim of the present study was to establish the origin and chemical phenotyping of neurons involved in skin innervation of the porcine hind leg. The dorsal root ganglia (DRGs) of the lumbar (L4-L6) and sacral (S1-S3) spinal nerves were visualized using the fluorescent tracer Fast Blue (FB). The morphometric analysis of FB-positive (FB+)neurons showed that in the L4, L5, S1 and S2 DRGs, the small-sized perikarya constituted the major population, whereas in the L6 and S3 DRGs the medium-sized cells made up the major population. In all these ganglia, large-sized FB+ perikarya constituted only a small percentage of all FB+ neurons. Immunohistochemistry revealed that small- and medium-sized FB+ perikarya contained sensory markers such as: substance P (SP), calcitonin gene related peptide (CGRP) and galanin (GAL); as well as various other factors such as somatostatin (SOM), calbindin-D28k (CB), pituitary adenylate cyclase-activating polypeptide (PACAP) and neuronal nitric oxide synthase (nNOS). Meanwhile large-sized FB+ perikarya usually expressed SP, CGRP or PACAP. In the lumbar DRGs, some large cells also contained SOM and CB. Double-labeling immunohistochemistry showed that SP-positive neurons co-expressed CGRP, GAL or PACAP; while PACAP-positive cells co-expressed GAL or nNOS. Neurons stained for SOM were also immunoreactive for CB or GAL, while neurons stained for nNOS were also immunoreactive for GAL. In conclusion, the present data has indicated that the distribution and chemical phenotyping of the porcine skin-projecting neurons are different within DRGs of the lumbar (forming a femoral nerve) and sacral (forming a sciatic nerve) spinal nerves.

The New 3D Printed Left Atrial Appendage Closure with a Novel Holdfast Device: A Pre-Clinical Feasibility Animal Study

Introduction Many patients undergoing cardiac surgery have risk factors for both atrial fibrillation (AF) and stroke. The left atrial appendage (LAA) is the primary site for thrombi formation. The most severe complication of emboli derived from LAA is stroke, which is associated with a 12-month mortality rate of 38% and a 12-month recurrence rate of 17%. The most common form of treatment for atrial fibrillation and stroke prevention is the pharmacological therapy with anticoagulants. Nonetheless this form of therapy is associated with high risk of major bleeding. Therefore LAA occlusion devices should be tested for their ability to reduce future cerebral ischemic events in patients with high-risk of haemorrhage. Aim The aim of this study was to evaluate the safety and feasibility of a novel left atrial appendage exclusion device with a minimally invasive introducer in a swine model. Materials and Methods A completely novel LAA device, which is composed of two tubes connected together using a specially created bail, was designed using finite element modelling (FEM) to obtain an optimal support force of 36 N at the closure line. The monolithic form of the occluder was obtained by using additive manufacturing of granular PA2200 powder with the technology of selective laser sintering (SLS). Fifteen swine were included in the feasibility tests, with 10 animals undergoing fourteen days of follow-up and 5 animals undergoing long-term observation of 3 months. For one animal, the follow-up was further prolonged to 6 months. The device was placed via minithoracotomy. After the observation period, all of the animals were euthanized, and their hearts were tested for LAA closure and local inflammatory and tissue response. Results After the defined observation period, all fifteen hearts were explanted. In all cases the full closure of the LAA was achieved. The macroscopic and microscopic evaluation of the explanted hearts showed that all devices were securely integrated in the surrounding tissues. No pericarditis or macroscopic signs of inflammation at the site of the device were found. All pigs were in good condition with normal weight gain and no other clinical symptoms. Conclusion This novel 3D printed left atrial appendage closure technique with a novel holdfast device was proven to be safe and feasible in all pigs. A benign healing process without inflammation and damage to the surrounding structures or evidence of new thrombi formation was observed. Moreover, the uncomplicated survival and full LAA exclusion in all animals demonstrate the efficacy of this novel and relatively cheap device. Further clinical evaluation and implementation studies should be performed to introduce this new technology into clinical practice.

MAGNETIC RESONANCE IMAGING AS A USEFUL TOOL FOR THE SELECTION OF PHARMACOLOGICAL AND SURGICAL TREATMENT OPTIONS FOR CANINE HYDROCEPHALUS

Abstract A group of 12 dogs, eight of small breeds and four of medium-sized breeds, were used in the study. Prior to the magnetic resonance imaging (MRI) scans, all dogs were subjected to neurological, laboratory, and electroencephalographic examinations, and trans-fontanel ultrasonography was additionally performed in two patients. The acquired obstructive hydrocephalus was diagnosed in two dogs, idiopathic obstructive hydrocephalus - in four patients, obstructive congenital hydrocephalus - in five dogs, and hydrocephalus ex vacuo- in one patient. Ten dogs were put under the pharmacological therapy, and in two patients the condition was treated surgically. MRI proved to be a valuable tool that supports selection of the appropriate pharmacological and surgical treatment. MRI scans also appear to be useful in monitoring an effectiveness of the applied form of treatment.

Evaluation, Description of the Technique, and Clinical Outcomes After Tibial Tuberosity Advancement With Cranial Fixation (TTA CF) for Cranial Cruciate Ligament Rupture in 22 Dogs

ABSTRACT The objective of this study is to describe a modified surgical technique for tibial tuberosity advancement with cranial fixation (TTA CF) in dogs with cranial cruciate insufficiency and to report long term clinical outcomes and complications. TTA CF was performed with a novel titanium implant. A description of the specific implant with guide, drill and saw guide, instrumentation, and template are provided, along with clinical outcomes, complications, owners’ evaluation, and a 1‐year postoperation follow‐up. Twenty two mixed breed dogs, with a median body weight of 23 kg (range, 11–45 kg) were included. The median age at surgery was 4 years (range, 1–8 years). Clinical bone healing was seen at a mean 10 weeks (range 6–14 weeks). The minor complication rate was 27% (n=6). No major complication occurred, and no revision surgery was required. Twenty‐one (95%) dogs had a good to excellent outcome 1 year after surgery. Currently there is no accepted best treatment of the canine cranial cruciate ligament deficient stifle. Most of TTA techniques are based on fixing the implant from the medial side of tibia. We report a modified TTA technique with cranial fixation of a titanium implant and suggest that the TTA CF surgical technique may be a feasible alternative to existing surgical procedures.

Low-field magnetic resonance imaging of changes after femoral osteosynthesis failure: a case report

We describe here a case study of a 16-month-old female European shorthair cat examined about 6 months after the osteosynthesis of a femoral fracture. Clinical examination revealed a non-weightbearing left limb, pain upon manipulation of the hip joint, complete immobilisation of the stifle joint and muscle atrophy in the left thigh. Low-field magnetic resonance images were acquired in sagittal, transverse and dorsal planes with T1-weighted spin echo, T2-weighted fast spin echo, T1-weighted gradient echo, gradient echo short tau inversion recovery and T1-weighted XBone sequences. Total examination time was 59 min 20 s. The obtained images revealed the presence of osteophytes on the surface of the femoral head, subluxation of the hip joint, atrophy and fatty infiltration of the quadriceps femoris muscle. The symmetry and size of callus in the fracture site were also evaluated. Based on the results of the magnetic resonance imaging exam, the patient was diagnosed with hip osteoarthritis, atrophy and fatty degeneration of the quadriceps femoris muscle with homogeneous and symmetrical distribution of callus in the fracture site. The results of this study confirm the high diagnostic value of low-field magnetic resonance imaging in diagnostics of musculoskeletal injuries in cats.

Diagnosis of cerebral ventriculomegaly in felines using 0.25 Tesla and 3 Tesla magnetic resonance imaging

Twenty European shorthair cats with neurological disorders, aged 1–3 years and with body weights of 2.6–4.05 kg, were studied in low-field and high-field magnetic resonance imaging systems. Aims of the study were to evaluate the dilation of lateral ventricles in the examined population of cats with the use of quantitative analysis methods and to identify any differences in the results of lowand high-field magnetic resonance imaging. The average brain height was determined to 27.3 mm, and the average volume of the brain was 10 699.7 mm3. Moderately enlarged ventricles were observed in 16 symptomatic cats. Moderate unilateral enlargement was observed in one cat. Mild ventricular asymmetry was described in four animals. The average difference in ventricular height between measurements obtained in lowand high-field magnetic resonance imaging was 0.37 ± 0.16% and for ventricular volume it was 0.62 ± 0.29%. The magnetic resonance imaging scan did not reveal statistically significant differences in brain height or volume between healthy and cats with ventriculomegaly. The differences in the results of lowand high-field magnetic resonance imaging were not statistically significant. Described findings could facilitate the interpretation of magnetic resonance images in cats with ventriculomegaly or hydrocephalus.

Low-field magnetic resonance imaging for 3D volume rendering of canine stifle joint pathologies: a case report

This article presents a case report in which complex deformities of the canine stifle joint were visualised using 3D volume rendering of images acquired in a low-field MRI system. The use of low-field MRI for 3D volume rendering has been described in human medicine, but no such reports are available as yet in veterinary medicine. A two-year-old male mongrel dog (8.5 kg body mass) with an unknown previous history of hindlimb lameness was presented to our clinic. The left stifle joint was hyperextended, slightly enlarged and it showed a limited range of motion. Three-dimensional sequences were used to visualise bones of the stifle joint. Optimal values of in-plane spatial resolution were obtained for small structures. The developed 3D model contributed to our understanding of the spatial localisation of bone deformities in the patient, which was crucial in surgical planning. This report shows that three-dimensional models do significantly enhance the clinical applicability of low-field MRI.

Single-stage Bilateral Tibial Tuberosity Advancement With Cranial Fixation in an English Bulldog – A Case Report

ABSTRACT This article presents a report of single‐stage bilateral tibial tuberosity advancement for the treatment of cranial cruciate ligament rupture in an English bulldog. The reconstruction was performed by a new surgical technique involving tibial tuberosity advancement and fixation with two cranially placed lag screws. The patient was able to ambulate normally at a walk without lameness four days postoperatively. Except for bruising of the surgical site, no complications were observed during a six‐month follow‐up period.