Treatment of Alzheimer's disease by transposition of the omentum

There is increasing evidence that cerebral hypoperfusion plays a key role in the development of Alzheimer's disease (AD). As one ages, cerebral blood flow (CBF) decreases as a direct reflection of a normal aging process. Coupled with this expected drop in CBF are a host of other factors, such as hypertension, stress, smoking, diabetes, cholesterol buildup, etc., which further decrease blood flow to the brain. Maintaining a critical level of CBF is essential if adequate amounts of oxygen and glucose are to be presented to neurons to sustain their cellular energy production (ATP). If CBF drops below a critical flow level, insufficient ATP will be produced and, if this situation is not corrected, neurons will deteriorate and eventually die. When a critical mass of neurons die in areas of the brain involved with cognition and memory, AD will result. Omentum transposition to the brain is a surgical procedure by which a large volume of blood and other biological agents can be delivered to the brain over an indefinite period of time. The omentum gives metabolic support to deteriorating neurons and its presence on the brain has resulted in the reversal of AD symptoms. Additionally, omentum transposition to the brain can markedly reduce senile plaque accumulation, but has no apparent effect on reducing neurofibrillary tangles. Omental transposition may play an important role in the future treatment of AD, especially in early and moderate cases.

Role of the omentum in the treatment of Alzheimer's disease

Beneficial post-operative changes in Alzheimer patients have been observed following omentum transposition to the brain. It is believed that these changes are to a certain degree due to the omentum's ability to increase cerebral blood flow (CBF). Since the omentum is known to increase CBF and to have angiogenic, neurotransmitters and nerve growth substances in its tissues, it is theorized that these biological factors favorably affect still viable but deteriorating ischemic-sensitive neurons located within the Alzheimer brain. Being able to 'rescue' these neurons by increasing CBF and adding neurotrophic factors from the omentum are mechanisms which are believed to increase neuronal energy (ATP production) which leads to cognitive improvement.

Omental transposition for cerebral infarction: a 13-year follow-up study

BACKGROUND

During the past decade there has been increasing use of omental transposition to the brain of patients who experienced neurologic sequelae after a cerebral infarction. This paper reports the long-term neurologic effects seen in a patient who underwent omental transposition 31 months after a stroke. Her postoperative follow-up period has been 13 years.

CASE DESCRIPTION

The patient had an expressive aphasia, a right hemiparesis and the inability to read which occurred immediately after her stroke. After surgery she demonstrated subjective and objective improvement in her speech and mobility. She also regained her ability to read shortly after surgery.

CONCLUSION

The patient demonstrated that omental transposition to the brain can improve neurologic function in the presence of a long-standing cerebral infarction and that the clinical improvement can be maintained over an extended period.

Omental transposition to the brain for Alzheimer's disease

Omental transposition (OT) to revascularize the brain was first performed in animals in the late 1960s, where it was shown that blood vessels originating from the omentum crossed through the omental-cerebral interface prior to developing into large-sized vessels that penetrated directly and deeply into the underlying brain. The additional cerebral blood flow coming from the omentum was of sufficient volume to protect an animal's brain from cerebral infarction even in the presence of middle cerebral artery ligation. It was also learned that the omentum was a rich source for neurotransmitters and omentum-derived nerve growth substance. OT to the brain is now being done for a variety of conditions which include strokes, TIAs, epilepsy, and Parkinson's disease. Of recent interest is the published information that OT may play some role in Alzheimer's disease (AD). The placement of the omentum on an AD brain has led to a profound decrease in senile plaque formation. The omentum may ultimately prove to be beneficial in reversing or at least stabilizing the dementia associated with the devastation of AD.

Decreased senile plaque density in Alzheimer neocortex adjacent to an omental transposition

Post-mortem studies of the brain of an Alzheimer patient indicate fewer senile plaques in the crests of cortical gyri underneath an omental transposition than in neighboring cortical areas.

Omental transposition for Alzheimer 's disease

A patient with Alzheimer's disease of long standing was treated with omental transposition to his brain. The rational for the procedure was to use the omentum to increase cerebral blood flow and to augment cholinergic neurotransmission activity. The patient improved for a year following surgery but after that time slowly began to decline neurologically and cognitively. However, according to Alzheimer's specialists who have followed the patient pre and postoperatively, he still maintains, 2.5 years after surgery, a higher level of performance than expected. There is theoretical and now a clinical suggestion that the omentum might play some role in the treatment of Alzheimer's disease. In view of the devastating nature of the disease, it seems reasonable to suggest that a limited controlled study be carried out to support or negate the benefit of the operation.

Brain and spinal cord revascularization by omental transposition

It has been learned over the years that placement of the pedicled omentum onto the brain and the spinal cord results in the rapid development of blood vessels that penetrate directly, vertically and deeply into the underlying CNS structure. Rapid clinical changes in some patients following omental transposition to the CNS raised the question as to whether the changes might be due not only to increased vascular perfusion, but to neurochemicals within omental tissue. Subsequent studies have shown that the omentum incorporates in its tissue neurotransmitters, nerve growth substances, gangliosides and angiogenic factors of high activity. These neurochemical and angiogenic substances are undoubtedly involved in some manner in the ability of axons in a transected spinal cord to grow at 1 mm/day and apparently make appropriate connections with distal spinal cord target tissue.

Coerulospinal fiber regeneration in transected feline spinal cord

After complete cat spinal cord transection, a collagen matrix was used to bridge the gap. Vascular supply was increased to the transection site with an omental pedicle. Before hardening, either 4-aminopyridine, laminin, glia maturation factor, or lipid angiogenic factor were mixed into the collagen. Surgically reconstructed animals were compared to transection-only controls and observed for 90 days. Fluoro-Gold was injected distal to the transection site on day 75. Immunocytochemical examination of brain and spinal cord tissue was done on day 90. Examination revealed supraspinal catecholaminergic fibers present in the collagen bridge and distal cord tissue only in cats with surgical reconstruction. Fluoro-Gold particles were found localized in locus coeruleus and other noradrenergic pontine neurons. Distal to the transection, double immunostaining with synaptophysin and tyrosine hydroxylase or dopamine-beta-hydroxylase revealed dot-like deposits closely apposed to preganglionic sympathetic neurons suggestive of synaptic connectivity to these targets. Results indicate that considerable outgrowth of specific supraspinal fibers can be induced following spinal transection and reconstruction, and that such fibers may be extending and contacting appropriate distal target tissue in the cord.

Axonal regeneration after spinal cord transection and reconstruction

Following complete transection of the spinal cord, cats were separated into 2 groups to undergo: (i) surgical reconstruction of the disconnected cord using a neuroactive agent mixed into a collagen matrix bridge and omental transposition and (ii) cord transection-only. After 90 days, animals were killed and the brain and spinal cord were removed for immunohistochemistry. Two weeks prior to sacrifice, spinal cord blood flows were measured and the retrograde axonal tracer Fluoro-Gold was injected below the transection site. Gross inspection of the spinal cords at autopsy showed excellent integration and continuity of the collagen matrix bridge with the proximal-distal stumps in the surgical reconstruction group. In the transection-only group, the proximal-distal stumps were connected by a fibrotic, often tapered in the middle, tissue bridge. Results show that omental transposition in the surgical reconstruction group increased spinal cord blood flow by 58% when compared to transection-only animals. Fluoro-Gold was found in mesencephalic and brainstem catecholaminergic and cholinergic neurons known to send axons to the spinal cord. Immunohistochemical staining with antibodies against catecholamine synthesizing enzymes tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) showed that surgical reconstruction treated cat cords but not transection-only, developed dense bundles of dopaminergic and noradrenergic fibers which were present in the collagen matrix bridge and in the distal spinal cord. Extension of these catecholaminergic fibers in surgical reconstruction treated cats showed maximal outgrowth of 90 mm below the transection site when the neuroactive agent 4-aminopyridine was mixed into the collagen matrix. In addition, the synaptogenic marker synaptophysin (SYN) was observed on preganglionic sympathetic neurons in association with dopaminergic- and noradrenergic-containing varicosities distal to the collagen matrix bridge, an indication that neo-synaptic contacts may have been made on these previously denervated neurons. No TH, DBH or SYN was observed below the transection site in transection-only cats. These findings indicate that surgical reconstruction treated cords can develop dense supraspinal fiber outgrowth across a treated collagen matrix bridge fed by an omental blood supply and that these fibers may have made neo-synaptic contacts with appropriate distal spinal cord target tissue.

Supraspinal fiber outgrowth and apparent synaptic remodelling across transected-reconstructed feline spinal cord

Following complete transection of the spinal cord at T9, 12 cats were separated into two groups: Group 1 received a collagen matrix (CM) treated with a neuroactive agent or with saline to bridge the spinal cord stumps and an omental transposition which was placed on the dorsal surface of the matrix; Group 2 received spinal cord transection only. Two cats received no spinal cord transection. After 90 days, all animals were killed and their brains and spinal cords were removed for immunohistochemical examination. Two weeks prior to sacrifice, spinal cord blood flows (SCBF) were measured and the retrograde axonal tracer Fluoro-Gold was injected below the transection site. Results show that omental transposition to the CM bridge in Group 1 animals increased SCBF an average 59% (assessed by clamping the omental blood supply to the cord). Examination of the brain 90 days after cord transection revealed Fluoro-Gold accumulation in the cytoplasm and processes of neurons located in the brainstem, midbrain, and diencephalic region which are known to contribute pathways to the spinal cord. Immunohistochemical staining with antibodies against the catecholamine synthesizing enzymes tyrosine hydroxylase and dopamine-B-hydroxylase, indicated that only Group I treated cats developed dense bundles of dopaminergic and noradrenergic fibers within the CM bridge and distal spinal cord tissue. These fibers were seen to extend 90 mm below the transection site. In addition, the synaptogenic marker synaptophysin (SYN) was observed in association with dopaminergic and noradrenergic fibers distal to the collagen matrix bridge, an indication that synaptic remodelling (regeneration) by previously denervated supraspinal axons may have occurred. Immunostaining for glial fibrillary acidic protein (GFAP) showed little to none reactive astrocytosis near the transection site of cats treated with the CM and omentum transposition (Group 1). No catecholaminergic fibers or SYN expression below the transection site were observed in Group 2 treated cats. Group 2 treated cats also showed dense immunostaining of GFAP near the transection site indicating significant astrocytic proliferation. These findings indicate that following complete spinal cord transection in cats and reconstruction with a treated collagen matrix and omental transposition, disconnected supraspinal fibers have the ability to regenerate for long anatomic distances and seemingly engage in synaptic remodelling with distal target tissue.

Regional cerebral blood flow after omental transposition to the ischaemic brain in man. A five year follow-up study

Regional cerebral blood flow, recorded by the 133Xenon inhalation method, was measured preoperatively and over a five years postoperative period in six patients with completed stroke and stabilized neurological deficits, who had undergone omental transposition for revascularization of the ischaemic brain. Comparisons of the preoperative blood flow values with those recorded following surgery demonstrate a postoperative increase of blood flow in five patients, with a high statistical degree of significance in four of them at the final examination. The flow increase was noted over the infarcted areas of the brain, upon which the omentum had been placed, as well as areas of the ischaemic hemisphere without omental placement and the contralateral hemisphere. Out of the five patients who demonstrated preoperative flow values below the expected norm for age, four showed final postoperative cerebral blood flow within the normal limits for their age. The results are consistent with the assumption that the transposed omentum played a role in postoperative blood flow increase, by adding collateral circulation to the ischaemic brain.

Collagen-omental graft in experimental spinal cord transection

Spinal cord transection was induced in 3 groups of cats. The gap was surgically reconstructed using a collagen matrix bridge (Group COL), collagen matrix + pedicled omentum graft (Group COM), or gelfoam (Group GEF). After a variable observation period, animals underwent distal cord horse-radish peroxidase (HRP) injections, somatosensory evoked potentials recordings and polarographic measurement of local spinal cord blood flow (1SCBF) using the hydrogen clearance technique. The cord tissue was removed for histologic and immunohistochemical analysis. Results showed retrograde HRP labelling of proximal segmental cord neurons and somatosensory evoked potentials were present in group COM but not in COL or GEF treated animals. Local SCBF was 66% and 87% higher in COM than COL or GEF animals respectively but this increase could be reversed if flow from the pedicled omentum was clamped-off. Histologic examination of cord tissue after 45 days revealed the presence of catecholaminergic axons distal to the transection site in COM but not COL or GEF groups. Moreover, after 90 days, the rate and density of tyrosine hydroxylase immunoreactive (TH-IR) axons was 10-fold higher in COM than COL group and this was accompanied by a proportionate increase in the vascular density between the two groups. GEF treated animals showed no regeneration of transected fibers and poor blood flow pattern. These findings indicate that the placement of a pedicled omentum on a collagen matrix bridge results in near restoration of normal SCBF to the reconstructed cord region and is associated with marked regeneration of axons below the lesion site.

Increased blood flow enhances axon regeneration after spinal transection

It is not known whether increasing the amount of blood flow to axotomized fibers in mammalian CNS can result in more robust sprouting. To find out, an intact pedicled omentum was surgically transposed to cover a collagen matrix gel used to bridge the transected cat spinal cord stumps. Control animals were similarly treated but did not receive the pedicled omentum. Twelve weeks after cord transection, animals receiving the pedicled omentum showed a 66% spinal cord blood flow increase over animals that did not. Moreover, treatment with the pedicled omentum increased the density of regenerating adrenergic axons 10-fold over the control group. These findings indicate that boosting flow with an omental graft to the collagen bridge site results in robust axonal outgrowth of spinal transected nerve fibers.

Vasoactive neurochemicals identified in omentum: a preliminary report

There has been increasing interest in biologic, immunologic, and chemical activity originating from omental tissue. Since clinical improvement has been observed in some patients very shortly after surgically transposing their omentum to the spinal cord or brain, the question arose as to whether neurochemicals might be present in omental tissue; a possible explanation for some of these neurological changes. This paper reports the presence of vasoactive neurochemicals in canine omental tissue. It remains unclear, however, whether the omentum produces or simply concentrates these and other neurochemicals.

Choline acetyltransferase activity in omental tissue

Choline acetyltransferase (ChAT), the enzyme responsible for the formation of ACh from choline and acetyl-coenzyme A, is a marker of cholinergic function and is significantly depressed in the brains of Alzheimer patients. It has been shown that omental tissue contains several neuroactive substances and causes revascularization when placed upon the brain of stroke patients. In this study, it was demonstrated that omental tissue exhibits specific ChAT activity. This activity was choline-dependent, inhibited by N-ethylmaleimide (a known ChAT inhibitor), and was characterized by kinetic parameters consistent with values for the neuronal enzyme. It is suggested that omental placement to the brain together with oral choline administration might prove to be useful for increasing ACh synthesis in Alzheimer's disease.

Increased vascular perfusion after administration of an omental lipid fraction

Recently, it has been reported that a lipid material is present within the omentum which has potent angiogenic activity. In the report being presented herein, the omental material was injected intramuscularly in the area of a standardized wound and at a site distant from the wound. Control animals were injected in a comparable manner using saline solution. The omental lipid material resulted in increased vascular perfusion in the wound regardless of whether the material was injected locally or remotely as measured by in vivo nuclear imaging techniques using tagged erythrocytes labeled with Technetium (Tc-99m). The ability to demonstrate that an omental lipid fraction can cause increased vascular perfusion has become possible because the omental lipid material is abundant in supply and relatively simple to prepare in large quantities.