Adrenal medullary explants as an efficient tool for pain control: adhesive biomolecular components are involved in graft function ex vivo

Adrenal medullary (AM) tissue transplantation into the central nervous system has been reported as a potential source of opioid peptides and catecholamines, which have analgesic effects useful in the control of chronic pain. Clinical trials, involving allogeneic graft of whole tissue explants into the subarachnoid space of the lumbar spinal cord, have already been reported. The aim of the present study was to determine whether adhesion and function of AM explants were related in some extent and how this relationship could account for improvement of AM tissue in terms of analgesic activity before grafting. Our experiments demonstrated a significant correlation between the adherent state of AM organoids during culture and a sustained secretion of Met-enkephalin and catecholamines by chromaffin cells (CC). These findings suggest that optimal culture condition for AM organoid adhesion can be defined for maintenance of tissue, prior to transplantation. Using immunocytochemistry, flow cytometry, and ELISA assays we showed that different cell adhesion molecules (CAMs) and extracellular matrix ECM proteins were expressed and released by AM cells during culture. Adherent AM organoids expressed increased levels of specific neural CAMs (NCAM and HNK-1 epitope) and integrin chains (beta1, alpha1, alpha2, alpha4, alpha5) and deposited markedly higher levels of fibronectin, but also laminin and collagen IV. Those molecules and probably adhesion processes they control might be involved in the maintenance of the CC-secreting neuroendocrine phenotype through cellular signaling pathways.

NMDA-induced spinal hypersensitivity is reduced by naturally derived peptide analog [Ser1]histogranin

N-methyl-D-aspartate (NMDA) receptor activation is thought to initiate a cellular cascade of events in the spinal cord that leads to neuronal hyperactivation and exaggerated persistent pain behaviors. Previous studies have demonstrated that implantation of adrenal medullary tissue into the spinal subarachnoid space reduces abnormal pain behaviors such as hyperalgesia and allodynia, possibly by intervening in the NMDA hyperexcitability cascade. Histogranin is a 15-amino acid peptide possessing NMDA receptor antagonist activity that has been isolated from adrenal medullary tissue. The present study examined the ability of stable analog [Ser1]histogranin to reduce abnormal pain-related behaviors induced in rats by direct activation of spinal NMDA receptors. The intrathecal injection of NMDA (5.0, 10.0, 20.0 nmol) produced significant thermal and mechanical hyperalgesia and tactile allodynia in a dose-related fashion. [Ser1]histogranin injected intrathecally prior to NMDA injections dose dependently attenuated or completely blocked hyperalgesia and allodynia. In addition, [Ser1]histogranin administration following NMDA-induction of abnormal pain behaviors reversed these effects. These results demonstrate that a naturally derived adrenal medullary neuropeptide can prevent and reverse NMDA-mediated spinal hyperexcitability. The distinct profile and robust activity of [Ser1]histogranin suggest novel alternative approaches in the management of pain and other CNS disorders involving abnormal excitatory neurotransmission.

[Non-insulin dependent diabetes in children and adolescents]

Maturity-onset diabetes of the young (MODY) is a clinically and genetically heterogenous disorder characterized by autosomal dominant inheritance with onset usually before 25 years of age, and a primary defect in glucose-stimulated insulin secretion. Genetic analyses have shown that mutations in at least five different genes can cause MODY. These are the genes encoding the glycolytic enzyme glucokinase, three liver-enriched transcription factors, hepatocyte nuclear factor (HNF)-1 alpha, HNF-1 beta and HNF-4 alpha, and the gene encoding the transcription factor, insulin promoter factor-1 (IPF-1). Patients with MODY3 run a considerable risk of developing diabetic eye disease. MODY2, related to glucokinase deficiency, is a relatively benign disorder which does not usually require insulin. Experiences with the three other MODY forms have so far been restricted to very few families. We present the first Norwegian family with MODY2. Furthermore, a previously published Norwegian family is shown to be MODY3. Subjects who fulfil the criteria of MODY can, by genetic testing, gain information important for prognosis and perhaps also for therapy.

Adrenal medullary transplants attenuate sensorimotor dysfunction in rats with peripheral neuropathy

Previous work in our laboratory has demonstrated that adrenal medullary transplants into the spinal subarachnoid space can alleviate neuropathic pain behaviors. The purpose of this study was to test the possibility that motor, as well as, sensory dysfunction is reduced by adrenal medullary transplants. Peripheral neuropathy was induced by a chronic constriction injury (CCI) of the sciatic nerve of rats. In addition to exaggerated responses to noxious and innocuous stimuli characteristic of peripheral nerve injury, severe impairment of hindpaw placing and grasping reflexes following CCI was observed. Two weeks following CCI, either adrenal medullary or control striated muscle tissue was implanted into the spinal subarachnoid space. Adrenal medullary, but not control transplants, produced significant restoration of hindlimb reflex function in animals with peripheral nerve injury. This was reversed by pretreatment with the alpha-adrenergic antagonist phentolamine, but not the opiate antagonist naloxone, suggesting a role for catecholamines secreted by the implanted cells in reflex recovery. Adrenal medullary transplants also attenuated hyperalgesia and allodynia resulting from nerve injury. These results indicate that adrenal medullary transplants can alleviate sensorimotor dysfunction consequent to peripheral nerve injury.

The influence of xenotransplant immunogenicity and immunosuppression on host MHC expression in the rat CNS

During the early stages following neural transplantation, host immune responses are initiated that are not normally found in the CNS including the induction of major histocompatibility antigens (MHC I and II). Previous laboratory findings have demonstrated prolonged survival of bovine chromaffin cells (BCC) in the rat CNS following transient immunosuppression with cyclosporin A (CSA) providing chromaffin cells are isolated from highly immunogenic passenger cells. To assess the influence of passenger and chromaffin cells on host MHC I and II expression, either BCC, nonchromaffin cell adrenal constituents (NCC), or adrenal medullary endothelial cells (EC) were implanted into the host. At 2 weeks postimplantation, robust BCC survival was obtained in CSA-treated animals. This correlated with low expression of MHC I at the host-graft border and the virtual absence of MHC II. Good BCC survival with reduced MHC I expression only was seen at 6 weeks postimplantation in animals transiently immunosuppressed (4 weeks). In contrast, poor survival was seen in the EC group (even with CSA treatment). In addition, marked MHC I and II expression was found in and around these grafts at 2 weeks, and was particularly intense in EC implanted animals. The results of this study suggest that nonchromaffin passenger cells in BCC preparations, most notably endothelial cells, can induce strong immune responses even in the presence of immunosuppression. Based on MHC staining, removal of these passenger cells can reduce host responses and improve long term survival of xenogeneic chromaffin cells in the CNS.

Suppression of neuropathic pain by a naturally-derived peptide with NMDA antagonist activity

Chronic pain may result from hyperexcitability following activation of spinal NMDA receptors. A naturally-derived mammalian peptide, histogranin, may possess NMDA antagonist activity. This study explored the possibility that stable analog [Ser1]Histogranin (SHG) could reduce chronic pain. Neuropathic pain was induced using the chronic constriction injury model (CCI). Intrathecal injection of SHG markedly attenuated the hyperalgesia and allodynia resulting from CCI, nearly normalizing responses. These results suggest that the natural peptide histogranin may be a novel adjunct in neuropathic pain management.

Xenogeneic adrenal medulla graft rejection rather than survival leads to increased rat striatal tyrosine hydroxylase immunoreactivity

Adrenal medulla has often been used as a donor tissue for transplantation into damaged central nervous system, with functional effects ranging from very good to nonexistent. The grafts have often been associated with morphological evidence of stimulated recipient dopaminergic fiber plasticity. The interpretation of these results has been difficult due to variable but mostly poor graft survival. The present study combines two experiments which evaluated the effects of intrastriatal xenogeneic adrenal medullary cell suspension grafts on rat recipients. First, bovine adrenal medulla cell suspension grafts of various compositions were tested for their functional and morphologic effects on immunosuppressed hemiparkinsonian rats. In the second experiment, graft rejection was allowed to occur in half of the rats in order to determine a possible contribution of the inflammatory/immune response to increased dopaminergic fiber plasticity of the recipient. At 28 days, grafts of all cell types survived well in immunosuppressed rats, but none of the grafted cell types was associated with either an amelioration of amphetamine-induced rotation or an increase in striatal tyrosine hydroxylase immunoreactivity around the graft site. The latter phenomenon was observed only in the nonimmunosuppressed rats with rejected grafts. Our findings strongly support the role of inflammatory/immune response to grafting in stimulating dopaminergic fiber plasticity and in the appearance of sprouting.

A natural peptide with NMDA inhibitory activity reduces tonic pain in the formalin model

The aim of this study was to assess whether a natural peptide, histogranin, isolated from chromaffin cells and possessing NMDA receptor inhibitory activity, could reduce tonic pain. Rats received intrathecal injections of the stable analog [Ser1]histogranin (SHG), prior to induction of the formalin response. SHG markedly suppressed the second tonic phase of the formalin response compared with saline vehicle. A U-shaped dose-response curve was obtained. SHG had no effect on phase 1 acute pain responses. These findings indicate that SHG acts in a similar fashion as other, non-peptide, NMDA antagonists in suppressing tonic, but not acute pain. The presence of the natural peptide in chromaffin cells may contribute to the analgesic effects of adrenal medullary implants.

Attenuation of formalin pain responses in the rat by adrenal medullary transplants in the spinal subarachnoid space

Previous reports have indicated that the implantation of adrenal medullary chromaffin cells into the spinal subarachnoid space can reduce both acute and chronic pain in several animal models. Recent findings suggest that acute and chronic pain alleviation may be mediated by distinct mechanisms. Since the formalin response is composed of an acute and tonic phase which can be pharmacologically distinguished, the ability of adrenal medullary implants to alter these responses was assessed. In rats with adrenal medullary transplants, both phases of the formalin response were attenuated, in contrast to control implanted animals. Suppression of the acute phase by adrenal medullary implants was reversed by the opiate antagonist naloxone, and partially reversed by the alpha-adrenergic antagonist phentolamine, suggesting that opioid peptides and catecholamines released by the implanted chromaffin cells contribute to the observed antinociception. However, neither antagonist altered the antinociceptive effects of adrenal medullary implants on the tonic phase of the formalin response. These results indicate that adrenal medullary implants in the spinal subarachnoid space alleviate acute and tonic pain via distinct pharmacologic mechanisms.

Loss of GABA-immunoreactivity in the spinal dorsal horn of rats with peripheral nerve injury and promotion of recovery by adrenal medullary grafts

Abnormal pain-related behaviour that accompanies peripheral nerve injury may be the result of altered spinal neuronal function. The long-term loss of inhibitory function by GABA neurons in particular may be a mechanism by which abnormal neural hyperactivity occurs, leading to exaggerated sensory processing following nerve injury. In order to assess this, changes in spinal GABA immunoreactivity at several time points following constriction nerve injury were quantified in parallel with behavioural assessments of abnormal sensory responses to noxious and innocuous stimuli. In addition, the effects of spinal adrenal medullary transplants were determined since previous findings have demonstrated alleviation of behavioural pain symptoms by such transplants. In response to unilateral sciatic nerve injury, GABAergic profiles normally found in lumbar dorsal horn laminae I-III significantly decreased. The decrease was apparent three days following ligation, particularly on the side ipsilateral to the nerve injury. By two weeks, no GABAergic profiles could be seen, with the deficit appearing in the spinal dorsal horn both ipsilateral and contralateral to the unilateral peripheral nerve injury. Marked decreases in GABA-immunoreactive profiles persisted for at least up to five weeks post-injury, with partial restoration occurring by seven weeks. However, even at seven weeks, losses in GABA-immunoreactive profiles persisted in the dorsal horn ipsilateral to peripheral nerve injury. These findings were comparable in animals receiving control striated muscle transplants. In contrast, adrenal medullary transplants markedly reduced the loss in GABA-immunoreactive profiles at all time-points examined. In addition, GABA-immunoreactive profile levels were normalized near that of intact animals by five to seven weeks following nerve injury in animals with adrenal medullary transplants. Parallel improvements in sensory responses to innocuous and noxious stimuli were also observed in these animals. The results of this study indicate that peripheral nerve injury can result in severe losses in spinal inhibitory mechanisms, possibly leading to exaggerated sensory processes in persistent pain states. In addition, adrenal medullary transplants may provide a neuroprotective function in promoting recovery and improving long-term survival of GABAergic neurons in the spinal dorsal horn which have been damaged by excitotoxic injury.

Alterations in rat spinal cord cGMP by peripheral nerve injury and adrenal medullary transplantation

Adrenal medullary chromaffin cells implanted into the spinal subarachnoid space can reduce abnormal pain-related responses in chronic pain models. Persistent pain is thought to involve the activation of N-methyl-D-aspartate (NMDA) receptors and subsequent production of nitric oxide (NO) and cyclic guanosine 3',5'-monophosphate (cGMP). Changes in dorsal horn levels of cGMP in the rat were determined in conjunction with alterations in pain behaviors following peripheral nerve injury and adrenal medullary transplantation. Results indicated increased spinal cGMP levels in parallel with thermal and mechanical hyperalgesia and tactile allodynia consequent to chronic constriction injury of the sciatic nerve in rats. Adrenal medullary, but not control transplants, attenuated the hyperalgesia and allodynia and decreased spinal cGMP content. These results suggest that adrenal medullary transplants may reduce abnormal pain by intervention in the spinal NMDA-NO cascade.

Cells expressing preproenkephalin mRNA in the rat pineal gland are not serotonin-producing pinealocytes: evidence using in situ hybridization combined with immunocytochemistry for serotonin

1. Preproenkephalin (PPEnk) mRNA expressing cells have been identified in rat pineal gland using radioactive in situ hybridization histochemistry. 2. Approximately 7% of the cells in the pineal gland (7.5 +/- 0.86, mean +/- 95% CI) express PPEnk mRNA. These cells are distributed throughout the pineal as either scattered single cells or small groups of cells with large round or oval nuclei. 3. Using in situ hybridization combined with ABC immunocytochemistry for serotonin (5-HT) in the same pineal sections, the PPEnk mRNA labeling cells are found not to be serotonin-immunoreactive cells. These data indicate that the PPEnk mRNA is expressed in a certain discrete subpopulation of cells in the rat pineal gland and these cells are not serotonin-producing pinealocytes. 4. The physiologic role of PPEnk-derived peptides in the pineal remains unknown. It is possible that these peptides either are synthesized and secreted as hormones or act as pineal paracrine signals.

Adrenal medullary implants reduce transsynaptic degeneration in the spinal cord of rats following chronic constriction nerve injury

Peripheral nerve injury causes abnormal sensory processing, possibly due in part to neuroplastic changes in the CNS. Following chronic constriction injury of the sciatic nerve, transsynaptic degeneration is suggested by the presence of "dark neurons" found in superficial laminae of spinal cord. Previous studies in our laboratory have shown that grafts of adrenal medullary cells into the spinal subarachnoid space can reduce abnormal pain due to peripheral nerve injury. A possible mechanism for these beneficial effects is the reduction or interruption of excitotoxic events that lead to pathological CNS changes. In order to examine this, 2 weeks after unilateral sciatic nerve ligation using a chronic constriction injury model, animals received either adrenal medullary or control striated muscle tissue implanted in the lumbar subarachnoid space. Control striated muscle-transplanted animals with nerve injury displayed thermal hyperalgesia and elevated numbers of dark neurons in the superficial dorsal horn, compared to intact animals. These dark neurons were increased bilaterally, but predominantly ipsilaterally, to nerve injury. In contrast, in animals with adrenal medullary transplants, reduced numbers of dark neurons were found in parallel with reduced hyperalgesia. The low numbers of dark neurons in these animals were similar to age-matched unoperated controls. Two months after nerve ligation, dark neurons were not found in animals with nerve injury, although abnormal ruffled-appearing neurons were still present in untransplanted animals, suggesting partial recovery of damaged spinal neurons. The results of this study suggest that spinal adrenal medullary transplants can attenuate the neuropathological events perpetuating nerve-injury-induced pain by enhancing recovery of spinal neurons from excitotoxic insult.

Update on cellular transplantation into the CNS as a novel therapy for chronic pain

The transplantation of cells that secrete neuroactive substances with analgesic properties into the CNS is a novel method that challenges current approaches in treating chronic pain. This review covers pre-clinical and clinical studies from both allogeneic and xenogeneic sources. One cell source that has been utilized successfully is the adrenal chromaffin cell, since such cells constitutively release catecholamines, opioid peptides, and neurotrophic factors; release can be augmented with nicotine. Other graft sources include AtT-20 and B-16 cell lines which release enkephalins and catecholamines, respectively. For grafting in rodents, adrenal medullary tissue pieces are transplanted to the subarachnoid space. Chromaffin cell transplants can decrease pain sensitivity in normal rats using standard acute pain tests (paw-pinch, hot-plate, and tail-flick). In addition, transplants can restore normal pain thresholds in rodent models of chronic pain (formalin, adjuvant-induced arthritis, and sciatic-nerve tie) which closely similate the pathologies of human chronic pain conditions. Xenografts have been studied due to concerns that future application for human pain may be limited by donor availability. Despite immune privileges of the CNS, xenografts require at least short-term immunosuppression to obtain a viable graft. Cell encapsulation is one method of sustaining a xenograft (in rat and human hosts) while circumventing the need for immunosuppression. Clinical studies have been initiated for terminal cancer patients with promising results as assessed by markedly reduced narcotic intake, visual analog scale ratings, and increased CSF levels of catecholamines and met-enkephalin.

Modulation of NMDA receptor expression in the rat spinal cord by peripheral nerve injury and adrenal medullary grafting

Excessive activation of N-methyl-D-aspartate (NMDA) receptors in the spinal cord consequent to peripheral injury has been implicated in the initiation of neuropathologic events leading to a state of chronic hyperexcitability and persistence of exaggerated sensory processing. In other CNS disease or injury states, NMDA-mediated neurotoxic damage is associated with a loss of NMDA receptors, and outcome may be improved by agents reducing NMDA activation. Previous findings in our laboratory have demonstrated that the transplantation of adrenal medullary tissue into the spinal subarachnoid space can alleviate sensory abnormalities and reduce the induction of a putative nitric oxide synthase consequent to peripheral nerve injury. In order to determine changes in NMDA receptor expression in the spinal cord following peripheral nerve injury and adrenal medullary grafting, NMDA receptor binding using a high-affinity competitive NMDA receptor antagonist, CGP-39653, and NMDAR1 subunit distribution using immunocytochemistry were investigated. Two weeks following peripheral nerve injury by loose ligation of the right sciatic nerve, either adrenal medullary or striated muscle (control) tissue pieces were implanted in the spinal subarachnoid space. Binding studies revealed a marked reduction in [3H]CGP-39653 binding at L4-L5 levels ipsilateral to peripheral nerve injury in control transplanted animals. In contrast, NMDA binding was normalized in adrenal medullary grafted animals. In addition, NMDAR1 immunoreactivity was reduced in both the dorsal horn neuropil and motor neurons of the ventral horn in animals with peripheral nerve injury, while levels in adrenal medullary grafted animals appeared similar to intact controls. These results suggest that adrenal medullary transplants reduce abnormal sensory processing resulting from peripheral injury by intervening in the spinal NMDA-excitotoxicity cascade.

Adrenal medullary grafts suppress c-fos induction in spinal neurons of arthritic rats

Expression of immediate-early genes such as c-fos is thought to reflect patterns of neuronal activity in the central nervous system. Prolonged increases in Fos-protein-like-immunoreactivity (FOS-LI) are seen in the dorsal horn of adjuvant arthritic rats, and parallel increased pain behavior. Grafts of adrenal medullary, but not control tissue, into the spinal subarachnoid space reduce pain behavior and suppress the induction of spinal Fos-LI in arthritic rats. This reduction is particularly marked in superficial laminae (I-II), but is also significant in deeper laminae (III-IV and V-VI). The results of this study suggest that adrenal medullary transplants reduce spinal cord hyperactivation consequent to painful peripheral inflammation.

Beta-adrenergic receptor subtypes in stress-induced behavioral depression

The purpose of this study was to examine the role of beta-adrenergic receptors in an animal model of stress-induced behavioral depression. beta-Adrenergic receptors in several brain regions and leukocytes of rats were determined by receptor binding techniques using 125I-cyanopindolol (cyp) as ligand and propranolol as displacer for total beta-adrenergic receptors, and ICI 86,406 for beta 1- and ICI 118,551 for beta 2-adrenergic receptors. We observed that the maximum number of binding sites (Bmax) and the apparent dissociation constant (Kd) of 125I-cyp binding to total beta-adrenergic receptors were increased in hippocampus of stressed rats with escape deficits (48 h after training) as compared to control rats. This increase was due to an increase in Bmax and Kd of 125I-cyp binding to beta 1-adrenergic receptors but not to beta 2-adrenergic receptors. There was no significant difference in beta 1-adrenergic receptors in cortex and cerebellum or beta 2-adrenergic receptors in hippocampus, cortex, cerebellum, or leukocytes of stressed (48 h after training) rats with escape deficits as compared to control rats. Interestingly, it was observed that beta 1- and beta 2-adrenergic receptors in various brain regions (cortex, cerebellum, and hippocampus) and beta 2-adrenergic receptors in leukocytes of stressed rats (10 days after training) were not significantly different from control rats, although escape deficits were still present. These results suggest that abnormalities in adrenergic neurotransmission are associated with an upregulation of beta 1-adrenergic receptors, which in turn may be involved in the early stages of behavioral deficits caused by uncontrollable shock.

Attenuation of NMDA-induced spinal hypersensitivity by adrenal medullary transplants

Abnormal sensory hyperexcitability consequent to peripheral injury most likely involves activation of N-methyl-D-aspartate (NMDA) receptors in the spinal cord. This activation may lead to a cascade of neuroplastic events resulting in the exaggeration of sensory responses and the persistence of pathological pain states. Recent studies in our laboratory have demonstrated that the transplantation of adrenal medullary cells into the spinal subarachnoid space can alleviate pathological pain symptoms, possibly by reducing spinal hyperexcitability. The purpose of this study was to assess spinal NMDA activation-induced hypersensitivity to noxious and innocuous stimuli, and determine whether adrenal medullary transplants can intervene favorably to reduce these responses. Animals with either adrenal medullary or control transplants were injected intrathecally with several doses of NMDA, and responses to sensory stimuli were determined over time. NMDA at all doses tested (1-50 nmol) produced significant thermal and mechanical hyperalgesia and tactile allodynia in control transplanted animals, with peak severity at 30 min post-injection. In contrast, both the severity and duration of these exaggerated sensory responses were markedly reduced in animals with adrenal medullary transplants. To assess a possible contribution of released opioid peptides and catecholamines from the transplanted chromaffin cells, animals were pretreated with opiate antagonist naloxone or alpha-adrenergic antagonist phentolamine. While naloxone was ineffective, the phentolamine partially attenuated, but did not completely abolish, the antinociceptive effects of the transplants. The results of these studies demonstrate that adrenal medullary grafts can reduce hypersensitivity responses to NMDA-mediated activation via alpha-adrenergic modulation in addition to other neuroprotective mechanisms.

Pharmacologic specificity of antidepressive activity by monoaminergic neural transplants

Previous studies in our laboratory have demonstrated the ability of monoaminergic transplants in the rat frontal cortex to produce antidepressive activity in both the learned helplessness model and the forced swimming test, as well as to increase monoamine levels in the implanted frontal cortex. These findings implicate increased cortical levels of norepinephrine (NE) and serotonin (5-HT) in the antidepressive activity of monoaminergic transplants. The goal of the present study was to characterize the pharmacologic mechanisms involved in the monoaminergic graft-induced antidepressive activity. Immobility scores in the forced swimming test (FST) were assessed after transplantation of 5-HT-containing pineal gland tissue, NE-containing adrenal medullary tissue, a combination of both tissues, or sciatic nerve (control) into the rat frontal cortex and compared to non-transplanted and chronic imipramine-treated rats. Monoaminergic transplants and imipramine treatment significantly reduced immobility scores in the FST in contrast to control transplanted or untreated animals. All groups were assessed pharmacologically with the adrenergic antagonists phentolamine (alpha) and propranolol (beta), and serotonergic antagonists metergoline (5-HT1/5-HT2) and pirenperone (5-HT2). Serotonergic antagonists, particularly the 5HT2 antagonist, blocked the reduction in FST immobility induced by the pineal implants. Adrenergic antagonists not only blocked FST immobility reductions in adrenal medullary grafted animals, but over-compensated for the adrenal transplants, producing a large increase in immobility. The FST reduction induced by pineal and adrenal cografts was blocked by all four monoaminergic antagonists. FST immobility scores in control transplanted and non-transplanted animals were not altered by any of the antagonists. The immobility reduction produced by chronic imipramine treatment was blocked significantly only by propranolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Transplantation of human chromaffin cells for control of intractable cancer pain

Adrenal medullary chromaffin cells produce high levels of endogenous opioid peptides. Recent data suggest that transplantation injected locally into the spinal subarachnoid space reduced intractable malignant pain. In order to determine the feasibility, the efficacy and the risks of using adrenal medullary tissue for control of irreducible pain, we have developed a transplantation protocol on cancer pain patients selected when they required chronic intrathecal injection of morphine and progressively increasing doses to maintain the level of analgesic effects. At the present time, our clinical trial involves 8 patients. We report here our initial results (mean follow-up: 5 months). The various data collected before and after the intrathecal administration of chromaffin cells included: 1) Pain evaluation over time, with concomitant narcotic intake, 2) CSF sampling through an implanted access port to determine the following biological parameters: biochemical assay for opioid peptides, cell count and phenotyping of lymphocytes, 3) peripheral blood samples for lymphocyte typing. The results confirm the efficacy of adrenal medullary transplantation into spinal CSF for controlling irreducible cancer pain. Complementary intrathecal and oral morphine were totally stopped in 2 cases and stabilized in 5 others. It seems essential to have an important volume of grafted tissue to achieve analgesia with high levels of metenkephalin in CSF. A progressive decrease in metenkephalin release was observed from 2 to 4 months after the transplantation. Two patients with a long-term follow-up (8 and 12 months) needed another intrathecal chromaffin cell graft.

Chromaffin cell xenografts in the rat neocortex can produce antidepressive activity in the forced swimming test

Adrenal medullary allografts, as well as other monoaminergic tissues, have been demonstrated in our laboratory to increase antidepressive activity when transplanted into the frontal neocortex of rats. Refinement in the optimal parameters for xenograft viability has indicated that isolated bovine chromaffin cells may be an improved source of graft donor tissue. The aim of the present study was to determine whether isolated bovine chromaffin cell grafts to the rat frontal neocortex could provide an alternative source of catecholamines for antidepressant activity. Isolated bovine chromaffin cells, isolated bovine fibroblasts, or an equal volume of vehicle were unilaterally implanted into the right or left frontal cortex or right visual cortex. All rats were assessed before and 6 weeks after transplantation using the forced swimming test, a popular measure of antidepressant activity. Bovine chromaffin cell grafts in either the right or left frontal cortex produced significant increases in antidepressant activity compared to grafts of bovine fibroblasts and sham-operated or nontransplanted rats. In contrast, bovine chromaffin cells transplanted to the visual cortex did not affect antidepressant activity. Bovine fibroblast grafts in the frontal cortex also induced slight increases in antidepressant activity, although significantly less than chromaffin cell grafts. Morphological analysis revealed robust survival of tyrosine hydroxylase-positive chromaffin cells that retained their in situ ultrastructure and occasionally formed synaptic connections with the host parenchyma. These results suggest that xenografted isolated bovine chromaffin cells can provide a viable source of catecholamines for antidepressive activity.

In vivo release of catecholamines from xenogeneic chromaffin cell grafts with antidepressive activity

Previous studies in our laboratory have demonstrated that allografts of adrenal medullary tissue and xenografts of isolated bovine chromaffin cells to the rat frontal cortex can increase antidepressive activity in two separate animal models. Biochemical and pharmacological evidence suggest that the most likely mechanism of these antidepressive effects is via local release of catecholamines into the surrounding cortical parenchyma. The aim of the present study was to directly characterize the antidepressive mechanism of chromaffin cell xenografts by utilizing in vivo microdialysis to measure extracellular catecholamine levels from bovine chromaffin cell and control implanted rat frontal cortex. Following transplantation, only bovine chromaffin cell grafted rats displayed significant increases in antidepressive activity, as assessed by the forced swimming test, compared to rats with grafts of bovine adrenal medullary fibroblasts or nontransplanted rats. In vivo microdialysis results revealed remarkably elevated levels of epinephrine (EPI) and norepinephrine (NE), but not dopamine, in dialysates from bovine chromaffin cell-transplanted frontal cortex. The most likely source of these enhanced EPI and NE levels is the grafted xenogeneic chromaffin cells. The results of this study directly demonstrate that xenografts of bovine chromaffin cells to the rat frontal cortex provide a releasable pool of catecholamines for antidepressive activity.

Transplantation of encapsulated bovine chromaffin cells in the sheep subarachnoid space: a preclinical study for the treatment of cancer pain

Chromaffin cells have been shown to release a combination of pain-reducing neuroactive compounds including catecholamines and opioid peptides. The allogeneic transplantation of chromaffin cells in the subarachnoid space has been shown to alleviate pain in various rodent models and possibly in terminal cancer patients. Because of the shortage of human cadaver donor tissue, we are investigating the possibility of transplanting xenogeneic cells in polymer capsules. In this technique, cells are surrounded by a permselective synthetic membrane whose pores are suitably sized to allow diffusion of nutrients, neurotransmitters and growth factors, but restrict the diffusion of the large molecules of the immune system and prevent contact with immunocompetent cells. The encapsulation technique therefore allows transplantation of xenogeneic tissue between species as well as retrieval of transplanted cells. Previously we have reported that encapsulated bovine chromaffin cells survive and alleviate pain in various rodent models. The purpose of the present study was to assess the feasibility of implanting a human sized device in a large animal model. Adrenals from 5 calves were surgically removed; chromaffin cells were isolated from these glands using a collagenase-based digestion-filtration technique. Cells were loaded into acrylic-based tubular (5 cm long, 920 microns wide) permselective capsules attached to silicone tethers. The capsules were maintained in vitro for at least 7 days following the encapsulation procedure. Nicotine evoked release was analyzed in a defined subgroup from each batch. One capsule was then implanted using a guiding cannula system in the lumbar subarachnoid space of each sheep for 4 (n = 5) and 8 (n = 1) wk. All capsules were retrieved intact by gentle pulling on the silicone tether. Except for one capsule, the evoked catecholamine release of the retrieved capsules was in the same range as that of other capsules from the same cohort that had been maintained in vitro. All retrieved capsules were devoid of host cell reaction. Clusters of viable cells dispersed in an alginate immobilizing matrix were observed throughout all the implanted capsules. This study demonstrates the feasibility of transplanting functional encapsulated xenogeneic chromaffin cells into the cerebrospinal fluid of a large animal model using a capsule of appropriate dimensions for human implants. We believe that these results suggest the appropriateness of human clinical trials in patients suffering from refractory terminal cancer pain.