Coerulospinal fiber regeneration in transected feline spinal cord

Omentomyelopexy for the Treatment of a Persistent Lumbar Pseudomeningocele: A Case Report With Technical Note

BACKGROUND AND IMPORTANCE

Pseudomeningoceles are extradural accumulations of cerebrospinal fluid. In most cases, they appear as a complication of spinal operations. Omentomyelopexy is a surgery in which an autologous omentum flap is implanted over the dural opening. We describe a case of persistent pseudomeningocele treated with omentomyelopexy.

CLINICAL PRESENTATION

A 37-year-old man sustained a T12-L1 AO B3 fracture during a motorcycle accident. He underwent posterolateral fusion and then neurological rehabilitation. Two years later, however, his condition worsened, and he experienced progressive weakness-he was diagnosed with an intramedullary cyst, which was treated with laminectomy, arachnolysis and cystotomy. A pseudomeningocele developed afterward, and the patient underwent multiple reoperations in the following years, none of which were effective. Omentomyelopexy, a complex procedure aimed to facilitate cerebrospinal fluid absorption and subsequent formation of a permanent membrane, was offered to the patient as a "last resort." After undergoing omentomyelopexy, his pseudomeningocele resolved.

CONCLUSION

Although it should be reserved for exceptionally pertinent cases, omentomyelopexy is a viable option for managing persistent pseudomeningocele. However, further research is needed to better understand the effects and benefits of omentomyelopexy in this context.

LC-QTOF-MS and 1H NMR Metabolomics Verifies Potential Use of Greater Omentum for Klebsiella pneumoniae Biofilm Eradication in Rats

Bacterial wound infections are a common problem associated with surgical interventions. In particular, biofilm-forming bacteria are hard to eradicate, and alternative methods of treatment based on covering wounds with vascularized flaps of tissue are being developed. The greater omentum is a complex organ covering the intestines in the abdomen, which support wound recovery following surgical procedures and exhibit natural antimicrobial activity that could improve biofilm eradication. We investigated changes in rats’ metabolome following Klebsiella pneumoniae infections, as well as the greater omentum’s ability for Klebsiella pneumoniae biofilm eradication. Rats received either sterile implants or implants covered with Klebsiella pneumoniae biofilm (placed in the peritoneum or greater omentum). Metabolic profiles were monitored at days 0, 2, and 5 after surgery using combined proton nuclear magnetic resonance (¹H NMR) and high performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC–QTOF-MS) measurements of urine samples followed by chemometric analysis. Obtained results indicated that grafting of the sterile implant to the greater omentum did not cause major disturbances in rats’ metabolism, whereas the sterile implant located in the peritoneum triggered metabolic perturbations related to tricarboxylic acid (TCA) cycle, as well as choline, tryptophan, and hippurate metabolism. Presence of implants colonized with Klebsiella pneumoniae biofilm resulted in similar levels of metabolic perturbations in both locations. Our findings confirmed that surgical procedures utilizing the greater omentum may have a practical use in wound healing and tissue regeneration in the future.

Axonal regeneration of different tracts following transplants of human glial restricted progenitors into the injured spinal cord in rats

The goal of this study was to compare the efficacy of human glial restricted progenitors (hGRPs) in promoting axonal growth of different tracts. We examined the potential of hGRPs grafted into a cervical (C4) dorsal column lesion to test sensory axons, and into a C4 hemisection to test motor tracts. The hGRPs, thawed from frozen stocks, were suspended in a PureCol matrix and grafted acutely into a C4 dorsal column or hemisection lesion. Control rats received PureCol only. Five weeks after transplantation, all transplanted cells survived in rats with the dorsal column lesion but only about half of the grafts in the hemisection. In the dorsal column lesion group, few sensory axons grew short distances into the lesion site of control animals. The presence of hGRPs transplants enhanced axonal growth significantly farther into the transplants. In the hemisection group, coerulospinal axons extended similarly into both control and transplant groups with no enhancement by the presence of hGRPs. Rubrospinal axons did not grow into the lesion even in the presence of hGRPs. However, reticulospinal and raphespinal axons grew for a significantly longer distance into the transplants. These results demonstrate the differential capacity of axonal growth/regeneration of the motor and sensory tracts based on their intrinsic abilities as well as their response to the modified environment induced by the hGRPs transplants. We conclude that hGRP transplants can modify the injury site for axon growth of sensory and some motor tracts, and suggest they could be combined with other interventions to restore connectivity.

Improving pancreatic islet in vitro functionality and transplantation efficiency by using heparin mimetic peptide nanofiber gels

Pancreatic islet transplantation is a promising treatment for type 1 diabetes. However, viability and functionality of the islets after transplantation are limited due to loss of integrity and destruction of blood vessel networks. Thus, it is important to provide a proper mechanically and biologically supportive environment for enhancing both in vitro islet culture and transplantation efficiency. Here, we demonstrate that heparin mimetic peptide amphiphile (HM-PA) nanofibrous network is a promising platform for these purposes. The islets cultured with peptide nanofiber gel containing growth factors exhibited a similar glucose stimulation index as that of the freshly isolated islets even after 7 days. After transplantation of islets to STZ-induced diabetic rats, 28 day-long monitoring displayed that islets that were transplanted in HM-PA nanofiber gels maintained better blood glucose levels at normal levels compared to the only islet transplantation group. In addition, intraperitoneal glucose tolerance test revealed that animals that were transplanted with islets within peptide gels showed a similar pattern with the healthy control group. Histological assessment showed that islets transplanted within peptide nanofiber gels demonstrated better islet integrity due to increased blood vessel density. This work demonstrates that using the HM-PA nanofiber gel platform enhances the islets function and islet transplantation efficiency both in vitro and in vivo.

Morphology of the Canine Omentum Part 1: Arterial Landmarks that Define the Omentum

Although the omentum remains an enigmatic organ, research during the last decades has revealed its fascinating functions including fat storage, fluid drainage, immune activity, angiogenesis and adhesion. While clinicians both in human and veterinary medicine are continuously exploring new potential omental applications, detailed anatomical data on the canine omentum are currently lacking, and information is often retrieved from human medicine. In this study, the topographic anatomy of the canine greater and lesser omentum is explored in depth. Current nomenclature is challenged, and a more detailed terminology is proposed. Consistent arteries that are contained within folds of the superficial omental wall are documented, described and named, as they can provide the anatomical landmarks that are necessary for unambiguous scientific communication on the canine omentum. In an included dissection video, the conclusions and in situ findings described in this study are demonstrated.

Spinal cord separation: MRI evidence of healing after omentum–collagen reconstruction

INTRODUCTION

Animal experimentation has demonstrated that omental-collagen bridge reconstruction of a transected spinal cord in cats can result in the growth of axons crossing the transection site which resulted in the return of motor and sensory activity. This paper raises the possibility that a comparable spinal cord reconstruction model could be possible for human application.

METHODS

Cats had their spinal cord transected at the T-9 level. This led to a gap at the transection site that was filled with semi-liquid collagen, followed by omental transposition onto the underlying collagen bridge, which had subsequently hardened. A comparable technique was used on a patient who had, as reported by magnetic resonance imaging (MRI), a complete spinal cord transection at the T-6 level.

RESULTS

Reconstruction of a transected spinal cord in cats using an omental-collagen bridge resulted in axons that grew across the transection site at the rate of 1 mm/day. Several animals developed forelimb and hindlimb locomotion. The patient in this paper had omental-collagen reconstruction of her cord and has clinically progressed to the point where she can ambulate with the use of a walker. The patient had a spinal cord defect of 4 cm, which, with multiple MRI studies, has shown the longitudinal development of a spinal cord connection in the area of the omental-collagen bridge that connects the proximal and distal ends of the transected spinal cord.

CONCLUSION

This report suggests that a transected spinal cord has the ability to heal when the spinal cord separation is reconstructed using an omental-collagen bridge. This technique has led to neurological improvement.

The evolution of omentum transposition: from lymphedema to spinal cord, stroke and Alzheimer's disease

It is now well established that the omentum incorporates into its tissues a variety of biological factors that exert a favorable effect on the central nervous system. Physiological characteristics of the omentum include edema absorption, fibrotic inhibition, blood-brain barrier penetration and, of major importance, angiogenic activity. Over several decades, studies have shown increasing clinical uses of the omentum following its placement on various structures within the body. This paper details the evolution of omental transposition (OT) up to the present at which time OT is being applied to the brain of Alzheimer disease (AD) patients. Success in this area raises the possibility that the omentum may prove to be a present-day treatment for patients with AD until future pharmaceutical and/or genetic forms of treatment are developed.

Cellular basis of tissue regeneration by omentum

The omentum is a sheet-like tissue attached to the greater curvature of the stomach and contains secondary lymphoid organs called milky spots. The omentum has been used for its healing potential for over 100 years by transposing the omental pedicle to injured organs (omental transposition), but the mechanism by which omentum helps the healing process of damaged tissues is not well understood. Omental transposition promotes expansion of pancreatic islets, hepatocytes, embryonic kidney, and neurons. Omental cells (OCs) can be activated by foreign bodies in vivo. Once activated, they become a rich source for growth factors and express pluripotent stem cell markers. Moreover, OCs become engrafted in injured tissues suggesting that they might function as stem cells.

Omentum consists of a variety of phenotypically and functionally distinctive cells. To understand the mechanism of tissue repair support by the omentum in more detail, we analyzed the cell subsets derived from the omentum on immune and inflammatory responses. Our data demonstrate that the omentum contains at least two groups of cells that support tissue repair, immunomodulatory myeloid derived suppressor cells and omnipotent stem cells that are indistinguishable from mesenchymal stem cells. Based on these data, we propose that the omentum is a designated organ for tissue repair and healing in response to foreign invasion and tissue damage.

Activated omentum becomes rich in factors that promote healing and tissue regeneration

In order to study the mechanism by which an omental pedicle promotes healing when applied to an injured site, we injected a foreign body into the abdominal cavity to activate the omentum. One week after the injection, we isolated the omentum and measured blood vessel density, blood content, growth and angiogenesis factors (VEGF and others), chemotactic factors (SDF-1 alpha), and progenitor cells (CXCR-4, WT-1). We found that the native omentum, which consisted mostly of adipose tissue, expanded the mass of its non-adipose part (milky spots) 15- to 20-fold. VEGF and other growth factors increased by two- to four-fold, blood vessel density by three-fold, and blood content by two-fold. The activated omentum also showed increases in SDF-1 alpha, CXCR-4, and WT-1 cells (factors and cells positively associated with tissue regeneration). Thus, we propose that an omentum activated by a foreign body (or by injury) greatly expands its milky-spot tissue and becomes rich in growth factors and progenitor cells that facilitate the healing and regeneration of injured tissue.

Delayed transplantation of olfactory ensheathing glia promotes sparing/regeneration of supraspinal axons in the contused adult rat spinal cord

The aim of this study was to determine the preferred time and environment for transplantation of olfactory ensheathing glia (OEG) into the moderately contused adult rat thoracic spinal cord. Purified OEG were suspended in culture medium with or without fibrinogen and injected into the contused cord segment at 30 min or 7 days after injury. Control animals received a contusion injury only or injection of only medium 7 days after contusion. The effects on axonal sparing/regeneration and functional recovery were evaluated 8 weeks after injury. The grafts largely filled the lesion site, reducing cavitation, and appeared continuous with the spinal nervous tissue. Whereas in 7d/medium only animals, 54% of spinal tissue within a 2.5-mm-long segment of cord centered at the injury site was spared, significantly more tissue was spared in 0 d/OEG-medium (73%), 0 d/OEG-fibrin (66%), 7 d/OEG-medium (70%), and 7 d/OEG-fibrin (68%) grafted animals. Compared with controls, the grafted animals exhibited more serotonergic axons within the transplant, the surrounding white matter, and the spinal cord up to at least 20 mm caudal to the graft. Retrograde tracing revealed that all but the 0 d/OEG-fibrin graft promoted sparing/regeneration of supraspinal axons compared with controls. Overall, the 7 d/OEG-medium group resulted in the best response, with twice as many labeled neurons in the brain compared with 7 d/medium only controls. Of the labeled neurons, 68% were located in the reticular formation, and 4% in the red, 4% in the raphe, and 5% in the vestibular nuclei. Hindlimb performance was modestly but significantly improved in the 7 d/OEG-medium group. Our results demonstrate that transplantation of OEG into the moderately contused adult rat thoracic spinal cord promotes sparing/regeneration of supraspinal axons and that 7 d transplantation is more effective than acute transplantation of OEG. Our results have relevant implications for future surgical repair strategies of the contused spinal cord.

Three-dimensional visualization of the distribution, growth, and regeneration of monoaminergic neurons in whole mounts of immature mammalian CNS

At birth, the opossum, Monodelphis domestica, corresponds roughly to a 14-day-old mouse embryo. The aim of these experiments was to compare the distribution of monoaminergic neurons in the two preparations during development and to follow their regeneration after injury. Procedures that allowed antibody staining to be visible in transparent whole mounts of the entire central nervous system (CNS) were devised. Neurons throughout the brain and spinal cord were stained for tyrosine hydroxylase (TH) and for serotonin (5-HT). At birth, patterns of monoaminergic cells in opossum CNS resembled those found in 14-day mouse embryos and other eutherian mammals. By postnatal day 5, immunoreactive cell bodies were clustered in appropriate regions of the midbrain and hindbrain, and numerous axons were already present throughout the spinal cord. Differences found in the opossum were the earlier presence of TH neurons in the olfactory bulb and of 5-HT neuronal perikarya in the spinal cord. Most, if not all, monoaminergic neurons in opossum were already postmitotic at birth. To study regeneration, crushes were made in cervical cords in culture. By 5 days, 8% of all TH-labeled axons and 14% of serotonergic axons had grown beyond lesions. Distal segments of monoaminergic axons degenerated. In CNS preparations from opossums older than 11 days, no regeneration of monoaminergic fibers occurred. Isolated embryonic mouse CNS also showed regeneration across spinal cord lesions, providing the possibility of using knockout and transgenic animals. Our procedures for whole-mount observation of identified cell bodies and their axons obviates the need for serial reconstructions and allows direct comparison of events occurring during development and regeneration.