Monitoring of Short-Term Erythropoietin Therapy in Rats with Acute Spinal Cord Injury Using Manganese-Enhanced Magnetic Resonance Imaging.

BACKGROUND AND PURPOSE: To evaluate the short-term outcome of erythropoietin (EPO) therapy in rats with spinal cord injury (SCI) using manganese-enhanced magnetic resonance imaging (MEMRI). METHODS: Rats were divided in an EPO and a control group. Laminectomy at Th11 was performed, followed by SCI. MnCl2 was applied into the cisterna magna and functional recovery was examined after injury using BBB-scoring. Then, rats were euthanized and the spinal cord was extracted for MEMRI. Finally, histological analysis was performed and correlated with MEMRI. RESULTS: EPO-treated animals showed significantly better functional recovery (P = .008, r = .62) and higher mean signal-to-noise ratio (SNR) in MEMRI compared to controls for slices 10-13 (P = .017, R(2) = .31) at the level of the lesion epicenter. Functional recovery correlated significantly with higher SNR values, determined using the mean SNR between slices 10 and 13 (P = .047, R(2) = .36). In this region, histology revealed a significantly decreased number of microglia cells and apoptosis in EPO-treated animals. CONCLUSION: MEMRI successfully depicts the therapeutic effect of EPO in early SCI that leads to a significant recovery in rats, a significantly reduced immune response and significantly reduced number of apoptotic cells at the height of the lesion epicenter.

Differential protein levels and post-translational modifications in spinal cord injury of the rat.

Although changes in protein expression in spinal cord injury (SCI) would be of pivotal interest, information so far is limited. It was therefore the aim of the study to determine protein levels and post-translational modifications in the early phase following SCI in the rat. SCI was induced in Sprague-Dawley rats and sham operated rats served as controls. A gel-based proteomic approach using two-dimensional gel electrophoresis followed by quantification with specific software and subsequent identification of differentially expressed proteins by nano-ESI-LC-MS/MS was applied. Proteins of several pathways and cascades were dysregulated in SCI: 14-3-3 epsilon protein, dynein light chain 1, and tubulin beta-5 chain showed higher levels in SCI, whereas adenylyl cyclase associated protein 1, dihydropyrimidinase-related protein 2, F-actin capping protein subunit beta, glyceraldehyde-3-phosphate dehydrogenase, stress-induced phosphoprotein 1 and transthyretin showed lower levels in the injured tissue. Post-translational modifications indicated free oxygen radical attack on proteins in SCI. The occurrence of stress is indicated by deranged stress-induced phosphoprotein 1 and signaling abnormalities are reflected by adenylyl cyclase-associated protein 1 and 14-3-3 epsilon protein. The findings propose the involvement of the corresponding cascades and challenge further work into aberrant signaling and oxidative stress in SCI, which may form the basis for experimental intervention for spinal cord trauma.

Small intestine submucosa (SIS) implants in experimental IPOM repair.

BACKGROUND: Synthetic meshes can cause adverse effects (e.g., adhesions, mesh infection) in intraperitoneal onlay mesh repair (IPOM). Although data for its biocompatibility as well as degradation behavior is still scarce, small intestine submucosa (SIS) implants have been suggested as a favorable alternative for IPOM repair. The aim of the study was to assess safety and efficacy of SIS used as allo- or xenograft in an experimental model of IPOM repair, with the purpose of creating a critical awareness for specific aspects of the biomesh concept among researchers and surgeons alike. Main outcome parameters were adhesion formation, tissue integration, shrinkage, and dislocation. MATERIALS AND METHODS: Open IPOM repair was performed in 16 Sprague Dawley rats and two minipigs. SIS implants were 2 x 2 cm in rats (one per animal) and 6 x 8 cm in pigs (four per animal). All implants were fixed with six nonresorbable sutures. Observation period was 17 and 28 d (n =8) in rats and 28 d in pigs. Outcome parameters were assessed macroscopically, and histologic samples (H and E staining) were obtained. RESULTS: Upon autopsy, SIS appeared to be only moderately integrated. Dislocation of five SIS implants in the rats and of two SIS implants in the pigs were observed although all sutures were still in place. No seroma formation or infection was detected macroscopically, but substantial shrinkage and adhesion formation at the margins of implants and suture sites were frequently observed. Histology confirmed the macroscopic finding of limited integration and substantial shrinkage. The pathomorphology was similar in both species. CONCLUSIONS: Small intestine submucosa implants are susceptible to shrinkage, dislocation, and adhesion formation in experimental IPOM repair in rats and pigs. These findings are in accordance with literature and warrant further investigations of SIS implants in hernia repair.

Fibrin sealant (Tissucol) enhances tissue integration of condensed polytetrafluoroethylene meshes and reduces early adhesion formation in experimental intraabdominal peritoneal onlay mesh repair.

BACKGROUND: The laparoscopic intraabdominal peritoneal onlay mesh repair (IPOM) is a common technique for the reinforcement of multiple ventral hernias or defined defects after laparotomies. However, the placement of synthetic meshes in the intraabdominal cavity can be associated with severe complications. Adhesions frequently originate from the implant and protruding parts of fixation devices, presenting a serious clinical problem with potentially detrimental consequences. This study was designed to assess the impact of fibrin sealing with Tissucol (FS; Baxter, Vienna, Austria) on adhesion formation to condensed polytetrafluoroethylene meshes (Motif Meshes, MM; Proxy Biomedical, Galway, Ireland) as well as on tissue integration of these implants in experimental IPOM repair in rats. It was tested whether FS application allowed the reduction of sutures for mesh fixation without increasing the risk of mesh dislocation. MATERIALS AND METHODS: Sixteen rats were assigned to the implantation of MM with four nonresorbable sutures (Synthofil; Ethicon, Norderstedt, Germany) with additional fibrin coating with 0.2 mL FS or to MM fixation with six nonresorbable sutures without FS (n = 8 per group). MM with 2 cm in diameter were implanted in open IPOM by a laparatomy. The observation period of 17 days ensured assessment of adhesions after the full degradation of FS. Adhesions were rated with the score suggested by Vandendael. Histology was performed. RESULTS: All eight MMs without FS sealing elicited severe (grade III) adhesions, whereas fibrin-sealed MM were rated mild in 1, moderate in 5, and severe in 2 cases. The superior finding in the FS group was statistically significant. Impaired integration of sutured-only MM was observed in four cases, whereas all FS-sealed MM were well integrated. CONCLUSIONS: FS improves the tissue integration, reduces early adhesion formation to cPTFE implants, and allows reduction of perforating fixation devices in experimental IPOM repair.

Manganese enhanced magnetic resonance imaging in a contusion model of spinal cord injury in rats: correlation with motor function.

OBJECTIVES: Various models of spinal cord injury in rodents have been established, and also techniques for lesion quantification. Measurement of the extent of the underlying injury is essential for monitoring the reproducibility of the experimental injury and assessment of therapeutic effects. In this study, we tested manganese-enhanced magnetic resonance imaging (MEMRI) for postmortem quantification of experimental spinal cord injury in rats. MATERIALS AND METHODS: Twelve rats were subjected to contusion injuries at the 11th thoracic vertebra, followed by MnCl2 injections into the cisterna magna. After 3 days of observation, postmortem MEMRI-features were correlated with values of locomotion testing and histology. RESULTS: MnCl2 yielded a strong contrast enhancement of the uninjured spinal cord, whereas no enhancement was observed at the injury site or caudally. Magnetic resonance imaging findings correlate closely with locomotor ratings. CONCLUSIONS: MEMRI represents a reliable method for visualization and functional assessment of spinal cord integrity in rats.

Adverse effects associated with the use of porcine cross-linked collagen implants in an experimental model of incisional hernia repair.

BACKGROUND: Porcine cross-linked collagen (PermaCol, PCL; TSL, Aldershot, United Kingdom) has been proposed as permanent biomaterial in incisional hernia repair. We evaluated the biocompatibility of PCL in an established animal model. MATERIAL AND METHODS: In 10 Sprague Dawley rats, two hernias per animal were created in the abdominal wall left and right of the linea alba (1.5 cm in diameter), and the peritoneum was spared. The lesions were left untreated for 10 days, until incisional hernias developed. These defects were covered with non-perforated (out-of-the-box, n = 12) or perforated (modified; n = 8) PCL (2 x 2 cm). In a first step, 12 non-perforated implants were tested in a short-term observation period of 17 days. Eight of these non-perforated implants were fibrin sealed (0.3 mL, Tissucol; Baxter, Vienna, Austria), whereas four non-perforated implants were sutured with non-resorbable material. In a second step, perforations were added as modification to PCL to facilitate drainage of fluids, cell ingrowth, and transgression of fibrin sealant. All perforated implants were fibrin sealed and included in a long-term observation period of 3 months. The observation periods allowed the evaluation of the complete degradation of the fibrin sealant fixation after 2 weeks and of the implant integration in a chronic timeframe. Implant sites were analyzed macroscopically and histologically. RESULTS: All PCL samples elicited strong local inflammation with signs of foreign body reaction. Integration of perforated PCL appeared limited after 3 months. Three animals had to be euthanized prior to intended time points because of transcutaneous migration of implants. CONCLUSIONS: In an experimental model of incisional hernia repair, PCL does not integrate well in the abdominal wall and shows poor biocompatibility.