Patients were included if their clinical state enabled MRI examination within the first week after transplantation. Exclusion criteria were as follows: claustrophobia, metallic implants, dyspnoea, and peritoneal dialysis. Informed consent was obtained from all participants.
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The study was approved by our University Review Board. MRI examinations were performed with a 1. In patients, the examinations were performed within one week after surgery. ROIs were placed on the largest cross-section of the kidney and were located peripherally within the renal parenchyma in the anterior, middle, and posterior part of the graft Figure 1. Measurements in transplant patients were correlated with basic laboratory parameters in the early period after transplantation, including eGFR, serum creatinine concentration SCr , proteinuria, serum uric acid and glucose concentration, white blood cell count WBC , red blood cell count RBC , and haematocrit HCT.
For intra-reader reproducibility calculation both observers repeated their measurements after six months. Images were anonymised before analysis. Intra-reader variability and interreader variability were assessed with the coefficient of variation CV and the intraclass correlation coefficient ICC. Differences in oxygenation estimates between patients and controls were tested with the independent samples t-test.
OUH - Abdominal transplantation imaging (Jacobsen)
P Results The clinical characteristics of patients are presented in Table 1. The intraclass correlation coefficient was 0. The overall inter-reader CV was The mean follow-up duration was Two patients were lost to follow-up. On the last measurements, the mean SCr was 1. Discussion To our knowledge, we showed for the first time that BOLD imaging performed early after transplantation has a limited value in predicting delayed renal graft function. Similar rejection rates were reported by Sadowski et al. We suspect that this could have been due to the short time between renal transplantation and scanning.
Breathing motions were the main source of image artefacts because, due to pain and common overhydration, patients in the early period after renal transplantation have a limited ability to hold their breath and to lie still in a supine position throughout the entire MRI examination. Thus, neither respiratory-gated nor breath-hold techniques guarantee images free from movement artefacts in this group of patients.
However, we preferred breath-hold sequences because of shorter total examination times. Xiao et al. We did not notice this problem in our group. The calculated MDC indicated that a difference of 0. However, it does not take into account the physiological differences that may introduce some variability to repeated scanning. Recently, two studies have assessed the reproducibility of repeated BOLD examinations.
In four patients, Park et al. However, that study lacked statistical power due to a small sample. Thoeny et al. Vermathen et al. Similar results were reported by Seif et al.
Complications of abdominal transplantation at CT and MRI
In the study by Xiao et al. Thus, the test may be considered to rule out the graft failure but not to confirm it. Moreover, the role of this method in predicting delayed graft function is limited. Our study had some limitations. Get access to the full version of this article. View access options below. You previously purchased this article through ReadCube. Institutional Login. Log in to Wiley Online Library. Purchase Instant Access.
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View Preview. Learn more Check out. Volume 21 , Issue 3 May e Related Information. Close Figure Viewer. Browse All Figures Return to Figure. Previous Figure Next Figure. Email or Customer ID. Many questions remain unsolved regarding the transplantation of BMSCs to repair spinal cord injuries. For instance, researchers do not know whether the transplanted cells or other autologous cells play the leading role after stem cell transplantation into the body.
Furthermore, it is unclear precisely how transplanted stem cells survive, differentiate, and migrate in vivo. In order to track the migration, differentiation and distribution of transplanted BMSCs in vivo , most groups have relied upon conventional tests like labeling transplanted cells with Green fluorescent protein or 5-bromodeoxyuridine. However, while these methods allow for the detection of transplanted cells at select time points using immunohistochemistry and immunofluorescence methods [ 10 ], they do not allow for real-time in vivo observation of migration, distribution or differentiation of transplanted cells.
The use of Magnetic resonance imaging MRI molecular morphology imaging to track transplanted stem cells is well-established, and magnetic tags are commonly used to visualize and track stem cells after transplantation into the body. Gadolinium Gd labels were used as early as , when Louie [ 11 ] used polymer particles within gadolinium-dimethylene pentaacetic acid Gd-DTPA to label transplanted cells.
While Gd labels have certain advantages in terms of tracking stem cells, a major weakness of the Gd label is its lack of specificity [ 12 — 14 ]. After treatment with lipase to sever the ester bond combining the aliphatic chains, the hydrophilic properties of the molecule were restored to increase contrast activity and demonstrate the effectiveness of Gd-DTPA-FA as a lipase activated magnetic resonance contrast agent [ 15 ].
Molecular Imaging of Stem Cell Transplantation for Neurodegenerative Diseases
Additionally, we constructed endothelial lipase lentiviral vectors carrying a promoter for neurofilament NF NF is expressed in the cytoplasm and axon of nerve cells and can be used to track the neuron-like cells that are derived from the stem cells transplanted to repair SCI [ 16 ]. In the present study, we describe an ideal method for dynamic in vivo monitoring of a target gene in real-time by using MRI. As applied to stem cells transplanted in a SCI model, these nanoparticles and lentiviral tools offer a novel method to monitor transplanted cells and provide further support for the role of BMSCs in promoting the recovery of nerve function after injury.
Flow cytometry showed that BMSCs are highly homogeneous in phenotype. For cell transduction and virus vectors were prepared as previously described [ 17 ]. The recombined lentivirus vector with NF promoter was produced and the infected rate was examed. GFP expression was visualized by fluorescence microscopy after 48 h and the numbers of total cells and GFP positive cells were assessed to determine transduction efficiency and viability.
The transduction efficiency was then calculated using the ratio of the number of GFP-positive cells to the total cell number Figure 1C — 1I. C Scheme of plasmid. E PRRL. EL-eGFP verctor. G Production of recombined lentivirus and infection with HepG2 cells. EL-eGFP lentivirus. As the CT images shown for all groups 1 day after injection, the hemorrhages resolved spontaneously in all cases.
The presence of hemorrhage abrogated the distinction of injured spinal cord from surrounding tissue in the region, as visualized by CT imaging. However, in post-processing color images, the boundary between the injuried spinal cord and adjacent tissue was distinguishable.
The green hematoma was noted to be distinct from blue spinal cord in Injury group. Blue thick funiculose tissue was noted to be connected to the normal blue spinal cord in Repaired group Supplementary Figure 1. In the Injury group, there was no observable increase in signal intensity of the spinal cord in T1WI from 1st day to 28th day except within the cavity formation. In contrast, hypersignal emerged in spinal cords of the Repaired group of rats in T1WI beginning on the 7th day, which was focused in injection site. This hypersignal was observed to increase and extend until the 14th day statu-post injection.
On day 28, the area of hypersignal in spinal cord was larger than before Figure 2 ; Supplementary Figure 2. In Normal group, the rat spinal cord was continuous and uninterrupted. In Injury group, there was no observable increase in signal intensity of the spinal cord in T1WI from 1st day to 28th day. In contrast, hypersignal emerged in spinal cords of the Repaired group of rats in T1WI beginning on the 7th day, which was further observed to be increased and extended until the 14th day statu-post injection.
On day 28, the area of hypersignal in spinal cord was larger than before. Arrows indicated the segmental SCI. Nissl staining of longitudinal sections in the normal group demonstrated that the neuronal structure was normal and uniformly distributed. Within the Repaired group, a decrease in the number of neurons and abnormal structure was observed at day 1, as compared to Injury. The normal structure of the cord gradually returned from day 14 to 28, and the neurons were observed to achieve an even distribution after this time Figure 3A.
Scanning electron microscopy showed that the myelin of the spinal cord in the Normal group maintained structural integrity and was organized in a tight concentric ring. In the Repaired group, the ultrastructure of spinal cord demonstrated significant normalization between day 14 and 28, demonstrating a much smaller cavity within the myelin Figure 3B.
B The electron microscopy scans. The Injury group and Repaired group showed many demyelinating axons.
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In Injury group, the degree of pathological changes of ultrastructure over time decreased, and the ultrastructure of BMSCs transplantation group was obviously improved. In the repaired group, DTT showed that a population of continuous nerve fibers that gradually increased from day 1 to day At day 28, approximately half the diameter of the spinal cord fibers were connected but arranged in an irregular pattern Figure 4A.
E staining of rat spinal cord tissue in the Normal, Injury1d and Repaired 28d group demonstrated that continuous spinal nerve fibers appeared in SCI site increasingly Figure 4B. In all injured animals, the hind legs were completely paralyzed after the rat spinal cord was transected completely.
Material and methods
The expression of neurofilament protein NF increased gradually in a disordered fashion within the Injury group. In the Repaired group, however, the expression of NF normalized, and the neuron-like cell populations appeared to have a more regular arrangement than Injury Figure 5. E staining of rat spinal cord tissue and BBB locomotor function score. A The DTT. In Injury group, the spinal cord fibers continuity were interrupted from the 1st day to 28th day, and end fibers arranged disorderly, colors were uneven; In Repaired group, the nerve fibers from the 1st day to 28th day, some fibers connected to the other end.
The color was almost consistent, but the arrangement of neurofibra was still disorder. In Normal group, visible normal spinal structure; b. In Injury 1d group, spinal cord was completely broken; c. In Repaired 28 d group, continuous spinal nerve fibers appeared in SCI site. C BBB locomotor function score. Figure 5: Immunofluorescence of spinal cord tissue. NF antibody red , dyeing Hoechst nucleus blue. It showed that the pathological changes in Injury group decreased with time obviously in longitudinal section.
In the first 7 days, transplanted cells were observed near the injection point, suggesting that the BMSCs differentiated into neurons and were mainly concentrated at the site of SCI.
media-aid.com/includes/2020-09-19/4405-hook-up.php The cells were gathered in situ , where the concentration is higher, with no obvious migration. The number of cells reached a maximum at day 14 and then gradually distributed along the segmental injury. Red arrow indicated segmental spinal cord injury Figure 6. However, there is no signal can be observed for T1W1 in 1st day or even until 28th day without NF promoter transfection Supplementary Figure 4. Figure 6: Schematic illustration of BMSCs transplantation differentiation, migration and distribution diagram.
The T1WI signal strength increased with the extension of time, at 14th day peaked, and then began to decline.
The area of high signal intensity increased with the extension of time, and the biggest area of high signal intensity appeared at 28th day. The weighted total signal strength was on the rise. C Schematic illustration of BMSCs transplantation differentiation, migration and distribution diagram. In the 7th day, NF positive cells were observed near the injection point, suggesting that the BMSCs had differentiated into neurons and were mainly concentrated at the site of SCI.
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The number of NF positive cells reached a maximum at 14th day, and then gradually distributed along the segmental injury to 28th day, NF positive cells distributed to both ends of the injury of spinal cord. BMSCs are a type of adult stem cells that can differentiate into neuron-like cells in vivo and in vitro [ 18 — 20 ]. Transplantation of BMSCs has been accomplished in situ e. In the present work, we used the microsyringe to direct inject BMSCs into the SCI lesion sites, which is also minimally invasive and favored for cellular delivery into the cerebrospinal fluid.
BMSCs have been observed to migrate and accumulate in the damaged areas of the nerve tissue and promote repair in previous studies [ 21 , 22 ]. In our previous studies, we transplanted BMSCs to the injury site in the spinal cord of rats and monkeys. We have observed that the transplanted cells not only survive and replicate at the site of injury but also induce a modest degree of functional recovery [ 5 , 23 ]. There is currently much interest in the fate of transplanted BMSCs with regard to differentiation, migration and distribution.
Most of the current understanding of the migration and distribution of BMSCs in the body has been informed by histology from dead animals based at select time points. Typical histological methods provide an imperfect picture and are unable to assess the migration and distribution of transplanted cells in vivo and in real-time.
By tagging stem cells with magnetic markers in the current study, we demonstrated the possibility of continuous and dynamic tracking of transplanted cells in vivo and in vitro using MRI. Using software for three-dimensional reconstruction [ 24 ], we are able to assess the location of cells at specific time points and also trace the movement of the cells through space.
Magnetic tracer technology using magnetic markers in the body is already widely used for the stem cell transplantation treatments of brain, heart, liver and kidney damage [ 25 ]. It has also been used in the in situ stem cell transplantation treatment of SCI [ 26 ]. In comparison to the traditional pathology methods, magnetic tracer technology offers multiple practical advantages.
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