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.

Modeling stroke in animals is essential for testing efficacy of new treatments; however, previous neuroprotective therapies, based on systemic delivery in rodents failed, exposing the need for model with improved clinical relevance. The purpose of this study was to develop endovascular approach for inducing ischemia in swine. To achieve that goal, we used intra-arterial administration of thrombin mixed with gadolinium and visualized the occlusion with real-time MRI. Placement of the microcatheter proximally to rete allowed trans-catheter perfusion of the ipsilateral hemisphere as visualized by contrast-enhanced perfusion MR scans. Dynamic T2*w MRI facilitated visualization of thrombin + Gd solution transiting through cerebral vasculature and persistent hyperintensities indicated occlusion. Area of trans-catheter perfusion dynamically quantified on representative slice before and after thrombin administration (22.20 ± 6.31 cm² vs. 13.28 ± 4.71 cm² respectively) indicated significantly reduced perfusion. ADC mapping showed evidence of ischemia as early as 27 min and follow-up T2w scans confirmed ischemic lesion (3.14 ± 1.41 cm²). Animals developed contralateral neurological deficits but were ambulatory. Our study has overcome long lasting challenge of inducing endovascular stroke model in pig. We were able to induce stroke using minimally invasive endovascular approach and observe in real-time formation of the thrombus, blockage of cerebral perfusion and eventually stroke lesion.

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. 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. 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. 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.

Disseminated diseases of the central nervous system such as amyotrophic lateral sclerosis (ALS) require that therapeutic agents are delivered and distributed broadly. Intrathecal route is attractive in that respect, but to date there was no methodology available allowing for optimization of this technique to assure safety and efficacy in a clinically relevant setting. Here, we report on interventional, MRI-guided approach for delivery of hydrogel-embedded glial progenitor cells facilitating cell placement over extended surface of the spinal cord in pigs and in naturally occurring ALS-like disease in dogs. Glial progenitors used as therapeutic agent were embedded in injectable hyaluronic acid-based hydrogel to support their survival and prevent sedimentation or removal. Intrathecal space was reached through lumbar puncture and the catheter was advanced under X-ray guidance to the cervical part of the spine. Animals were then transferred to MRI suite for MRI-guided injection. Interventional and follow-up MRI as well as histopathology demonstrated successful and predictable placement of embedded cells and safety of the procedure.

The purpose of this study was to examine the safety of the long-term application of QuikClot Combat Gauze, ChitoGauze PRO and Celox Gauze using a swine model. The study was conducted on nine pigs weighing approximately 30 kg, which were randomly divided into three groups. Under deep anesthesia, the pigs underwent complete transverse cutting of the femoral artery in the groin region. Hemostatic dressings were left in the wound for 24 hours. The animals were euthanized 24 hours after dressing application. In each group, macroscopic and microscopic severe changes and shock symptoms were observed in the lungs, liver, kidneys and heart. Fibrino-gaseous embolic material was found in the pulmonary artery of each group and in the lung vessels of the animals from the ChitoGauze PRO and Celox Gauze groups. In conclusion, the long-term application of the evaluated hemostatic dressings has the risk of coagulopathy and reaching the progressive stage of shock. The residues from the hemostatic dressings can ingress into the systemic circulation, thereby increasing the risk of embolus formation. Because of these harmful effects, the evaluated hemostatic dressings are not appropriate for long-term use. Future studies are needed on the consequences of the long-term application of these hemostatic agents.

Articles | Veterinární medicína | Agricultural Journals