Current concepts on the expression of neurotrophins in the greater omentum

The Potential Crosstalk Between the Brain and Visceral Adipose Tissue in Alzheimer's Development

The bidirectional communication between the brain and peripheral organs have been widely documented, but the impact of visceral adipose tissue (VAT) dysfunction and its relation to structural and functional brain changes have yet to be fully elucidated. This review initially examines the clinical evidence supporting associations between the brain and VAT before visiting the roles of the autonomic nervous system, fat and glucose metabolism, neuroinflammation, and metabolites. Finally, the possible effects and potential mechanisms of the brain-VAT axis on the pathogenesis of Alzheimer's disease are discussed, providing new insights regarding future prevention and therapeutic strategies.

The Application of an Omentum Graft or Flap in Spinal Cord Injury

Background: Spinal cord injury (SCI) causes a primary injury at the lesion site and triggers a secondary injury and prolonged inflammation. There has been no definitive treatment till now. Promoting angiogenesis is one of the most important strategies for functional recovery after SCI. The omentum, abundant in blood and lymph vessels, possesses the potent ability of tissue regeneration. Methods: The present work examines the efficacy of autologous omentum, either as a flap (with vascular connection intact) or graft (severed vascular connection), on spinal nerve regeneration. After contusive SCI in rats, a thin sheath of omentum was grafted to the injured spinal cord. Results: Omental graft improved behavior scores significantly from the 3rd to 6th week after injury (6th week, 5.5 ± 0.5 vs. 8.6 ± 1.3, p < 0.05). Furthermore, the reduction in cavity and the preservation of class III β-tubulin-positive nerve fibers in the injury area was noted. Next, the free omental flap was transposed to a completely transected SCI in rats through a pre-implanted tunnel. The flap remained vascularized and survived well several weeks after the operation. At 16 weeks post-treatment, SCI rats with omentum flap treatment displayed the preservation of significantly more nerve fibers (p < 0.05) and a reduced injured cavity, though locomotor scores were similar. Conclusions: Taken together, the findings of this study indicate that treatment with an omental graft or transposition of an omental flap on an injured spinal cord has a positive effect on nerve protection and tissue preservation in SCI rats. The current data highlight the importance of omentum in clinical applications.

Ovarian BDNF promotes survival, migration, and attachment of tumor precursors originated from p53 mutant fallopian tube epithelial cells

High-grade serous ovarian carcinoma (HGSOC) is the most lethal gynecological malignancy. New evidence supports a hypothesis that HGSOC can originate from fallopian tube epithelium (FTE). It is unclear how genetic alterations and pathophysiological processes drive the progression of FTE tumor precursors into widespread HGSOCs. In this study, we uncovered that brain-derived neurotrophic factor (BDNF) in the follicular fluid stimulates the tropomyosin receptor kinase B (TrkB)-expressing FTE cells to promote their survival, migration, and attachment. Using in vitro and in vivo models, we further identified that the acquisition of common TP53 gain-of-function (GOF) mutations in FTE cells led to enhanced BDNF/TrkB signaling compared to that of FTE cells with TP53 loss-of-function (LOF) mutations. Different mutant p53 proteins can either increase TrkB transcription or enhance TrkB endocytic recycling. Our findings have demonstrated possible interplays between genetic alterations in FTE tumor precursors (i.e., p53 GOF mutations) and pathophysiological processes (i.e., the release of follicular fluid upon ovulation) during the initiation of HGSOC from the fallopian tube. Our data revealed molecular events underlying the link between HGSOC tumorigenesis and ovulation, a physiological process that has been associated with risk factors of HGSOC.

The Potential of Mesothelial Cells in Tissue Engineering and Regenerative Medicine Applications

Injury to the serosa through injurious agents such as radiation, surgery, infection and disease results in the loss of the protective surface mesothelium and often leads to fibrous adhesion formation. Mechanisms that increase the rate of mesothialisation are therefore actively being investigated in order to reduce the formation of adhesions. These include intraperitoneal delivery of cultured mesothelial cells as well as administration of factors that are known to increase mesothelial proliferation and migration. An exciting alternative that has only recently received attention, is the possible role of mesothelial progenitor cells in the repair and regeneration of denuded serosal areas. Accumulating evidence suggests that such a population exists and under certain conditions is able to form a number of defined cell types indicating a degree of plasticity. Such properties may explain the extensive use of mesothelial cells in various tissue engineering applications including the development of vascular conduits and peripheral nerve replacements. It is likely that with the rapid explosion in the fields of tissue engineering and regenerative medicine, a greater understanding of the potential of mesothelial progenitor cells to repair, replace and possibly regenerate damaged or defective tissue will be uncovered.

The Omental Pedicle Flap in Dogs Revised and Refined: A Cadaver Study

OBJECTIVE

To expand current knowledge on the canine omental vasculature and refine the existing lengthening technique of the canine omentum.

STUDY DESIGN

Ex vivo study.

ANIMALS

Canine cadavers (n=20).

METHODS

In 10 canine cadavers the omental arteries were mapped using intravascular latex injection and these results were used to create an omental pedicle flap based on the splenic artery in 10 additional cadavers. The operating range of the flap was recorded with particular attention to the main regions of interest for omental transposition in dogs (axillary and inguinal regions).

RESULTS

The superficial and deep omental leaves were each predominantly supplied by a left and a right marginal omental artery that anastomosed near the caudal omental border into a superficial and a deep omental arch, respectively. Anastomoses between arteries of the superficial and the deep omental leaves were weak and inconsistent, except for 1 anastomosis that was found in 8 of 10 dogs. By transposing the intact omentum, the right axilla could be reached in 3 dogs, both axillae in 1 dog, and both groins in all cadavers. In all cases, the omental pedicle reached to and beyond the axillary and inguinal regions. By unfolding the pedicle leaves, the width of the pedicle tip could be doubled.

CONCLUSION

When lengthening the omentum is necessary to reach extra-abdominal structures, the omental pedicle flap based on the splenic artery appears to preserve the omental vascular supply. These observations warrant further clinical trials to evaluate this new omtental flap technique 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.

Omentum transposition surgery for patients with Alzheimer's disease: a case series

OBJECTIVE

To examine effect of omentum transposition surgery (OT) in Alzheimer's disease (AD).

METHODS

Within-subjects design, also known as repeated-measures design, was used. OT was performed on six biopsy-confirmed AD patients (three to the left and right hemispheres each). Follow-up was conducted over 16-50 months. Outcome measures included the sum of the sub-scores of the clinical dementia rating scale (CDRSS), dementia severity rating scale (DSRS), mini-mental status exam (MMSE) and neuropsychiatric inventory (NPI), all normalized to 0-1.0. Outcomes were compared to baseline values and to expected decline with and without cholinesterase inhibitors therapy (ChEI).

RESULTS

Compared to baseline and to expected decline with ChEI, CDRSS scores were 22 and 39% less impaired at means of 14 and 25 months post-OT, and DSRS scores were 12 and 22% less impaired at means of 14 and 19 months post-OT (p<0.0001). Compared to baseline and expected course with and without ChEI, the MMSE scores of the left hemisphere OT patients were not significantly different for 11, 17 and 22 months respectively (p>0.49), while those of the right hemisphere OT patients more rapidly declined. The two patients with significant pre-operative behavioral problems markedly improved; NPI severity scores decreased by 23 (16%) and 78 (54%) points and were sustained for 22 and 42 months.

DISCUSSION

OT yielded cognitive, functional or behavioral improvement for up to 3.5 years in these AD patients. Compared to randomized ChEI clinical trials, OT was 34 times more likely to produce clinically significant improvement. Basic research to identify the mechanisms underlying the therapeutic effect of omentum is warranted.

Angiogenic capacity of human omental stem cells

OBJECTIVES

The goals of the present study are to obtain, expand and characterize a stem cell population from human omentum and to evaluate its in vivo angiogenic capacities.

METHODS

Human omental CD34+ cells were obtained from samples of human omentum by density gradient centrifugation in Ficoll. Proliferative pattern, marker expression (by flow cytometry) and angiogenic growth factor synthesis by omental cell cultures were determined. In vivo angiogenic capacity of the cells was evaluated in rats.

RESULTS

Omental stem cells showed a high rate of proliferation (Ki67 staining), expressed CD34 marker and synthesized bFGF and VEGF. When implanted in rats, omental cells promoted neovascularization. Human omental cells were localized in rat tissue, mainly forming the endothelium of neo-vessels. Implantation of omental cells also facilitated angiogenesis of rat origin.

CONCLUSION

CD34+ cell population of human omentum could be responsible for the clinical benefit of omental transplantation by promoting angiogenesis and synthesizing angiogenic growth factors to facilitate revascularization of injured tissue.

Attenuation of pain perception after transposition of the greater omentum to the cauda equina region of rats--a preliminary observation

BACKGROUND

This paper addresses a specific experimental design to suggest the possible role of the greater omentum in the modulation of pain in rats.

METHODS

Fifteen male Sprague-Dawley rats weighing between 275 and 325 g were selected. The animals were randomized and then anesthetized with pentobarbital (35 mg/kg) and divided into three groups: (1) sham: laparotomy followed by laminectomy with exposure of the spinal epidural space (n=5); (2) transposition of pedicled omentum (n=5) to the cauda equina epidural space; and (3) transposition of pedicled omentum (n=5) to the cauda equina intradural space. The animals were operated upon and once more randomized by an independent investigator, so that the groups were thought to be similar during post-operative testing. The latency of paw withdrawal to noxious heat stimulation was tested and the values (seconds) plotted for 1, 3, 6, 11, 14 and 30 days after surgery. Randomization codes were open after the animals were euthanized. The analysis of variance (ANOVA) without replication was applied for each of the dataset and comparisons established among the different study groups involved. The omenta were removed and standard immunohistochemistry was performed for gamma-amino-butyric acid (GABA), serotonin, calcitonin-gene related protein (CGRP), vascular intestinal peptide (VIP) and Met-enkephalin.

RESULTS

The response to high heating rates of stimulation favored intradural versus sham and epidural omental transpositions. High and low noxious heat stimulation suggested an increased threshold to noxious stimulation after the 3 and 30 days of omental transposition. In the low heat stimulation series, responses were comparatively higher than in the sham animals.

CONCLUSIONS

The suggested increased threshold of response to noxious stimulation after transposition of the greater omentum onto the spinal cord of rats suggested a novel role of the omentum and a potential future application in the clinical arena.

Enhanced Prospects for Drug Delivery and Brain Targeting by the Choroid Plexus–CSF Route

The choroid plexus (CP), i.e., the blood-cerebrospinal fluid barrier (BCSFB) interface, is an epithelial boundary exploitable for drug delivery to brain. Agents transported from blood to lateral ventricles are convected by CSF volume transmission (bulk flow) to many periventricular targets. These include the caudate, hippocampus, specialized circumventricular organs, hypothalamus, and the downstream pia-glia and arachnoid membranes. The CSF circulatory system normally provides micronutrients, neurotrophins, hormones, neuropeptides, and growth factors extensively to neuronal networks. Therefore, drugs directed to CSF can modulate a variety of endocrine, immunologic, and behavioral phenomema; and can help to restore brain interstitial and cellular homeostasis disrupted by disease and trauma. This review integrates information from animal models that demonstrates marked physiologic effects of substances introduced into the ventricular system. It also recapitulates how pharmacologic agents administered into the CSF system prevent disease or enhance the brain's ability to recover from chemical and physical insults. In regard to drug distribution in the CNS, the BCSFB interaction with the blood-brain barrier is discussed. With a view toward translational CSF pharmacotherapy, there are several promising innovations in progress: bone marrow cell infusions, CP encapsulation and transplants, neural stem cell augmentation, phage display of peptide ligands for CP epithelium, CSF gene transfer, regulation of leukocyte and cytokine trafficking at the BCSFB, and the purification of neurotoxic CSF in degenerative states. The progressively increasing pharmacological significance of the CP-CSF nexus is analyzed in light of treating AIDS, multiple sclerosis, stroke, hydrocephalus, and Alzheimer's disease.