Viability and Functionality of Bovine Chromaffin Cells Encapsulated into Alginate-PLL Microcapsules with a Liquefied Inner Core

Implantation of adrenal medullary bovine chromaffin cells (BCC), which synthesize and secrete a combination of pain-reducing neuroactive compounds including catecholamines and opioid peptides, has been proposed for the treatment of intractable cancer pain. Macro- or microencapsulation of such cells within semi-permeable membranes is expected to protect the transplant from the host's immune system. In the present study, we report the viability and functionality of BCC encapsulated into microcapsules of alginate-poly-L-lysine (PLL) with a liquefied inner core. The experiment was carried out during 44 days. Empty microcapsules were characterized in terms of morphology, permeability, and mechanical resistance. At the same time, the viability and functionality of both encapsulated and nonencapsulated BCC were evaluated in vitro. We obtained viable BCC with excellent functionality: immunocytochemical analysis revealed robust survival of chromaffin cells 30 days after isolation and microencapsulation. HPLC assay showed that encapsulated BCC released catecholamines basally during the time course study. Taken together, these results demonstrate that viable BCC can be successfully encapsulated into alginate-PLL microcapsules with a liquefied inner core.

One-Year Chromaffin Cell Allograft Survival in Cancer Patients with Chronic Pain: Morphological and Functional Evidence

The control of chronic pain through transplantation of chromaffin cells has been reported over the past few years. Analgesic effects are principally due to the production of opioid peptides and catecholamines by chromaffin cells. Clinical trials have been reported with allografts consisting of whole-tissue fragments implanted into the subarachnoid space of the lumbar spinal cord (14,19,36). In the present study, allogeneic grafts were successfully used to control chronic pain in two patients over a period of 1 yr based on patient reported pain scores, morphine intake, and CSF levels of Met-enkephalin. Macroscopic examination at autopsy located the transplanted tissue fragments in the form of multilobulated nodules at the level of the spinal axis and cauda equina. Immunocytochemical microscopy showed neuroendocrine cells are positive for chromagranin A (CGA), and enzymes tyrosine hydroxylase (TH) and dopamine-β-hydroxylase (DβH). The results suggest that there is a relationship between analgesic effect, Met-enkephalin levels in CSF, and the presence of chromaffin cells surviving in spinal subarachnoid space.

Motor cortex stimulation for neuropathic pain

Since the initial publication of Tsubokawa in 1991, epidural motor cortex stimulation (MCS) is increasingly reported as an effective surgical option for the treatment of refractory neuropathic pain although its mechanism of action remains poorly understood. The authors review the extensive literature published over the last 15 years on central and neuropathic pain. Optimal patient selection remains difficult and the value of pharmacological tests or transcranial magnetic stimulation in predicting the efficacy of MCS has not been established. Pre-operative functional magnetic resonance imaging (fMRI), 3-dimensional volume MRI, neuronavigation and intra-operative neurophysiological monitoring have contributed to improvements in the technique for identifying the precise location of the targeted motor cortical area and the correct placement of the electrode array. MCS should be considered as the treatment of choice in post-stroke pain, thalamic pain or facial anesthesia dolorosa. In brachial plexus avulsion pain, it is preferable to propose initially dorsal root entry zone (DREZ)-tomy; MCS may be offered after DREZotomy has failed to control the pain. In our experience, the results of MCS on phantom limb pain are promising. In general, the efficacy of MCS depends on: a) the accurate placement of the stimulation electrode over the appropriate area of the motor cortex, and b) on sophisticated programming of the stimulation parameters. A better understanding of the MCS mechanism of action will probably make it possible to adjust better the stimulation parameters. The conclusions of multicentered randomised studies, now in progress, will be very useful and are likely to promote further research and clinical applications in this field.

Cell therapy of pain: Characterization of human fetal chromaffin cells at early adrenal medulla development

Adult adrenal chromaffin cells are being utilized for therapeutic transplantation. With the prospect of using fetal chromaffin cells in pain therapy, we studied their phenotype, proliferative power, function, and growth in vitro and in situ in order to determine the optimal time for implantation. Between 7 and 10 gestational weeks (GW), we isolated, in vitro, two types of chromaffin cells with a noradrenergic phenotype akin to that observed, in situ. Among the adherent chromaffin cells first observed in vitro, only a few samples expressed met-enkephalin, whereas almost all the neurosphere-like colonies, which appeared later, expressed it. However, neither of the two types of populations expressed an adrenergic phenotype in line with that observed in situ. At the upper limits of the voluntary abortion period authorized in France, this phenotype (12 GW) and met-enkephalin expression (13 GW) were evidenced in situ. For the first time in man, we demonstrate the secretion of noradrenaline in vitro by the two populations of cells. Consistent with this result, we also noted dopamine beta hydroxylase (DbetaH) mRNA expression in vitro and in situ within this period. These observations on the expression of these biological factors indicate that 9-10 GW would be the best stage for sampling these cells for preclinical transplantation experiments.

Intrathecal grafting of porcine chromaffin cells reduces formalin-evoked c-Fos expression in the rat spinal cord

Chromaffin cells from the adrenal gland secrete a combination of neuroactive compounds including catecholamines, opioid peptides, and growth factors that have strong analgesic effects, especially when administered intrathecally. Preclinical studies of intrathecal implantation with xenogeneic bovine chromaffin cells in rats have provided conflicting data with regard to analgesic effects, and recent concern over risk of prion transmission has precluded their use in human clinical trials. We previously developed a new, safer source of adult adrenal chromaffin cells of porcine origin and demonstrated an in vivo antinociceptive effect in the formalin test, a rodent model of tonic pain. The goal of the present study was to confirm porcine chromaffin cell analgesic effects at the molecular level by evaluating neural activity as reflected by spinal cord c-Fos protein expression. To this end, the expression of c-Fos in response to intraplantar formalin injection was evaluated in animals following intrathecal grafting of 10(6) porcine or bovine chromaffin cells. For the two species, adrenal chromaffin cells significantly reduced the tonic phases of the formalin response. Similarly, c-Fos-like immunoreactive neurons were markedly reduced in the dorsal horns of animals that had received injections of xenogeneic chromaffin cells. This reduction was observed in both the superficial (I-II) and deep (V-VI) lamina of the dorsal horn. The present study demonstrates that both xenogeneic porcine and bovine chromaffin cells transplanted into the spinal subarachnoid space of the rat can suppress formalin-evoked c-Fos expression equally, in parallel with suppression of nociceptive behaviors in the tonic phase of the test. These findings confirm previous reports that adrenal chromaffin cells may produce antinociception by inhibiting activation of nociceptive neurons in the spinal dorsal horn. Taken together these results support the concept that porcine chromaffin cells may offer an alternative xenogeneic cell source for transplants delivering pain-reducing neuroactive substances.

[Cost-benefit evaluation of spinal cord stimulation treatment for failed-back surgery syndrome patients]

BACKGROUND AND PURPOSE

Spinal cord stimulation is a well-known treatment of rigorously selected failed-back surgery syndrome patients. Efficacy levels over 50% of pain relief have been reported in long-term studies. The objective of this multicenter prospective evaluation was to analyze the cost to benefit ratio of spinal cord stimulation treatment for failed back surgery syndrome patients.

METHODS

Nine hospitals (pain evaluation and treatment centers) were involved in the study. Forty-three patients were selected and implanted between January 1999 and January 2000. For each patient, pre- and post-operative evaluations (6, 12 and 24 months after implantation) were performed to assess pain relief and economical impact on pain treatment costs.

RESULTS

After 24 months, mean 60% pain relief was achieved as assessed with the neuropathic pain score using a Visual Analog Scale (success rate=70%), whereas low-back pain was moderately reduced (29%). The Oswestry Disability questionnaire score was improved by a mean 39%. Costs of pain treatment (medication, consultation, other) are reduced by a mean 64% (1705 Euro) per patient per year.

CONCLUSIONS

This study confirms a clear analgesic effect on neuropathic sciatalgia, and moderate attenuation of low-back pain. One particular interest of this study is the medico-economic prospective evaluation showing that the initial cost of the implanted device is compensated by a significant, early, and stable reduction in the cost of associated pain therapies.

Grafts of immortalized chromaffin cells bio-engineered to improve met-enkephalin release also reduce formalin-evoked c-fos expression in rat spinal cord

Transplantation of adrenal medullary tissue for terminal cancer pain has been tested clinically, but this approach is not practical for routine use because of the shortage of organ donors and lack of tissue homogeneity. As a first alternative step, we have generated immortalized chromaffin cells over-expressing opioid peptides, namely met-enkephalin. Rat chromaffin cells have been genetically modified with vectors containing expression cassettes with either synthetic met-enkephalin or pro-enkephalin gene coding regions, fused with the nerve growth factor signal peptide for secretion. After stable transfection and differentiation in vitro, met-enkephalin and pro-enkephalin cells had higher met-enkephalin immunoreactivity and secreted met-enkephalin levels, compared to control cells containing the expression vector only. In the formalin hindpaw-injection model, 15 days after subarachnoid transplant of cells, grafts of met-enkephalin and pro-enkephalin cells significantly reduced the number of formalin-evoked c-fos immunoreactive spinal neurons in the spinal cord, compared to grafts of vector-alone chromaffin cells. The use of such expandable cell lines, for chronic spinal delivery of opiates, could offer an attractive and safe alternative strategy based on ex vivo gene therapy for the control of opioid-sensitive chronic pain.

Intrathecal xenogeneic chromaffin cell grafts reduce nociceptive behavior in a rodent tonic pain model

Adrenal medullary chromaffin cells synthetize and secrete a combination of pain-reducing neuroactive compounds including catecholamines and opioid peptides. Previous reports have shown that implantation of chromaffin cells into the spinal subarachnoid space can reduce both acute and chronic pain in several animal models. We recently demonstrated that human chromaffin cell grafts in the cerebrospinal fluid (CSF) could alleviate intractable cancer pain after failure of systemic opiates. However, wider application of this approach was limited by the limited availability of allogeneic donor material. Alternatively, chromaffin cells from xenogeneic sources such as bovine adrenal medulla were successful in the experimental treatment of pain, but recent concern over risk of prion transmission precluded use of bovine grafts in human clinical trials. The objective of the present study was to investigate the possibility of developing a new xenogeneic porcine source of therapeutic chromaffin cells because this strategy is currently considered the safest for transplantation in man. In the present study, we report the isolation and the characterization of primary porcine chromaffin cells (PCC) compared to bovine cells. We show, for the first time, that these cells grafted in the rat subarachnoid space can attenuate pain-related behaviors as assessed by the formalin test, a model of tonic pain. Moreover, in addition to behavioral studies, immunohistochemical analysis revealed robust survival of chromaffin cells 35 days after transplantation. Taken together, these results support the concept that porcine chromaffin cells may offer an alternative xenogeneic cell source for transplants delivering pain-reducing neuroactive substances.

Deep Brain Stimulation for Parkinson’s Disease: Correlation between Intraoperative Subthalamic Nucleus Neurophysiology and Most Effective Contacts

Though intraoperative neurophysiology is essential to precisely define the definitive target, little is known regarding its predictive value in defining the most effective contact for chronic deep brain stimulation. In this retrospective study, we reviewed the correlation between intraoperative neurophysiology and contacts selected for chronic stimulation. Twenty consecutive patients implanted for subthalamic nucleus (STN) stimulation were reviewed. There was no significant correlation between the electrophysiologically defined STN and the most effective contact for chronic stimulation at 3 months or at 6 months. Furthermore, there was a discrepancy between the most effective contact for rigidity versus akinesia or tremor at 3 months. Interestingly, at 3 months, the same electrode contact was maximally efficient for rigidity, akinesia and tremor in only 13 of the 39 cases. This lack of correlation did not affect the global improvement.

[Intrathecal baclofen. Experimental and pharmacokinetic studies]

Baclofen, the most effective drug to treat spasticity, is a specific agonist of gamma-aminobutyric acid-B receptors, and is very abondant in the superficial layers of the spinal cord. Given orally, baclofen does not easily penetrate the blood-barrier, and is distributed equally to the brain and spinal cord. After oral administration of baclofen, the drug is resorbed by more than 80-90% in the stomach and bowel and is eliminated by urinary excretion. Failure of oral medication to produce sufficient relief of spasticity is due to the poor passage of the drug across the blood-brain barrier. In animals the concentration in brain is less than 1/10 of the blood levels. The problem of insufficient anti-spastic efficacy (in relation to the rate of side-effects) after systemic medication may be overcome by local application in spinal CSF. Direct intrathecal administration of baclofen in the treatment of severe spasticity was proposed in 1984 by Richard Penn with the objective to carry out a selective spinal distribution of the active principle thus avoiding supraspinal side effects. The pharmacokinetics of baclofen in animal and man after intrathecal administration have been investigated to determine the CSF pharmacokinetic parameters.

[Use of auditory brain stem implant in a patient with bilateral vestibular schwannoma (type 2 neurofibromatosis]

Surgical technique and functional results of implantation of the acoustic implant of the brain stem (BS) are described for a 16-year-old patient with bilateral vestibular shvannoma (neurofibromatosis of type 2). Initially, a large (IV degree) tumor was removed from the left cerebellopontile angle using the translabyrinthine-transcochlear approach. The function of the facial nerve recovered completely. The BS implant was implanted a year later in the course of removing shvannoma from the right cerebellopontile angle using the above approach. The patient received 22-channel implant Nucleus-CI22M. Speech intelligibility improved by 90-100%. BS implantation is today the only effective method of reestablishment of acoustic sensations in patients with bilateral destruction of the acoustic nerves due to bilateral vestibular shvannoma.

Chronic motor cortex stimulation for phantom limb pain: correlations between pain relief and functional imaging studies

Chronic motor cortex stimulation (CMCS) has provided satisfactory control of pain in patients with central or trigeminal neuropathic pain. We used this technique in 3 patients with intractable phantom limb pain after upper limb amputation. Functional magnetic resonance imaging (fMRI) correlated to anatomical MRI permitted frameless image guidance for electrode placement. Pain control was obtained for all the patients initially and the relief was stable in 2 of the 3 patients at 2 year follow-up. CMCS can be used to relieve phantom limb pain. fMRI data are useful in assisting the neurosurgeon in electrode placement for this indication.

[Feasability of a back school assessment programme]

OBJECTIVES

Testing the feasability of a back school assessment programme in two populations of people suffering with chronic low back pain.

MATERIAL

Twenty-nine patients were randomly included in a chronic low back pain assessment programme (15 patients waiting for back school and 14 patients after back school).

METHODS

The programme was made of the measure of the age, the sex, the body mass index, the pain (VAS, St Antoine Hospitals Pain Questionnaire - SAPQ), the anxiety, the depression, the RIII nociceptive reflex, the fingertip-floor distance, the strength of the flexors and of the extensors of the lumbar spine (CybexR 6000 isocinetic dynamometer), the lumbar function (EIFEL, Dougados), the Dallas self-questionnaire. The Back School Education programme was made of five sessions (information, ergonomics, extension exercises).

RESULTS

Comparing the two populations we did not observe significant differences concerning the age, the body mass index, the anxiety and depression levels, the pain (VAS, SAPA, RIII nociceptive reflex), the lumbar stiffness, the lumbar disability, the quality of life; the patients who had achieved back school had a peak torque of the flexors and a ratio flexors/extensors significantly lower. Comparing men and women we observed significant differences in the SAPQ and the muscles strength. The SAPQ was correlated with the depression and anxiety levels, the lumbar disability, the peak torque of the flexors. The VAS was correlated with the age, the lumbar stiffness, the depression level, the peak torque of the flexors. The RIII nociceptive reflex was correlated with the ratio flexors/extensors.

CONCLUSION

This study present some biases but this objective assessment of chronic low back pain appeared as feasible. The pain must be investigated in term of intensity, expression, alleviation. The impairment of the flexors muscles in women and after back school has to be confirmed. The different tests are relevant to determinate the efficiency of the back school programmes.

The surgical management of spasticity

Neurosurgery is only considered for severe spasticity following the failure of noninvasive management (adequate medical and physical therapy). The patients are carefully selected, based on rigorous multidisciplinary clinical assessment. In this we evaluate the contribution of the spasticity to the disability and any residual voluntary motor function. The goals for each patient are: (a) improvement of function and autonomy; (b) control of pain; and (c) prevention of orthopaedic disorders. To achieve these objectives, the surgical procedure must be selective and reduce the excessive hypertonia without suppressing useful muscle tone and limb functions. The surgical procedures are: (1) Classical neuro-ablative techniques (peripheral neurotomies, dorsal rhizotomies) and their modern modifications using microsurgery and intra-operative neural stimulation (dorsal root entry zone: DREZotomy). These techniques are destructive and irreversible, with the reduced muscle tone reflecting the nerve topography. It is mainly indicated when patients have localized spasticity without useful mobility. (2) Conservative techniques based on a neurophysiological control mechanism. These procedures are totally reversible. The methods involve chronic neurostimulation of the spinal cord or the cerebellum. There are only a few patients for whom this is indicated. Conversely, chronic intrathecal administration of baclofen, using an implantable pump, is well established in the treatment of diffuse spasticity of spinal origin. From reports in the literature, we critically review the respective indications in terms of function, clinical progression and the topographic extent of the spasticity.

Methodological and technical issues for integrating functional magnetic resonance imaging data in a neuronavigational system

OBJECTIVE

The aim of this article was to analyze the technical and methodological issues resulting from the use of functional magnetic resonance image (fMRI) data in a frameless stereotactic device for brain tumor or pain surgery (chronic motor cortex stimulation).

METHODS

A total of 32 candidates, 26 for brain tumor surgery and six chronic motor cortex stimulation, were studied by fMRI scanning (61 procedures) and intraoperative cortical brain mapping under general anesthesia. The fMRI data obtained were analyzed with the Statistical Parametric Mapping 99 software, with an initial analysis threshold corresponding to P < 0.001. Subsequently, the fMRI data were registered in a frameless stereotactic neuronavigational device and correlated to brain mapping.

RESULTS

Correspondence between fMRI-activated areas and cortical mapping in primary motor areas was good in 28 patients (87%), although fMRI-activated areas were highly dependent on the choice of paradigms and analysis thresholds. Primary sensory- and secondary motor-activated areas were not correlated to cortical brain mapping. Functional mislocalization as a result of insufficient correction of the echo-planar distortion was identified in four patients (13%). Analysis thresholds (from P < 0.0001 to P < 10(-12)) more restrictive than the initial threshold (P < 0.001) had to be used in 25 of the 28 patients studied, so that fMRI motor data could be matched to cortical mapping spatial data. These analysis thresholds were not predictable preoperatively. Maximal tumor resection was accomplished in all patients with brain tumors. Chronic motor cortex electrode placement was successful in each patient (significant pain relief >50% on the visual analog pain scale).

CONCLUSION

In brain tumor surgery, fMRI data are helpful in surgical planning and guiding intraoperative brain mapping. The registration of fMRI data in anatomic slices or in the frameless stereotactic neuronavigational device, however, remained a potential source of functional mislocalization. Electrode placement for chronic motor cortex stimulation is a good indication to use fMRI data registered in a neuronavigational system and could replace somatosensory evoked potentials in detection of the central sulcus.

Virtual movements activate primary sensorimotor areas in amputees: report of three cases

OBJECTIVE

In our multidisciplinary pain clinic, three patients with amputated limbs and with surgical indications for chronic motor cortex stimulation for phantom limb pain were selected for their ability to voluntarily move the missing limb. The sensation of being able to move a missing limb at will occurs quite frequently among traumatic amputees, but the ability to control it sufficiently to perform a functional magnetic resonance imaging (fMRI) examination is more rarely encountered. We used motor fMRI to study these virtual movements.

METHODS

In two patients with upper-limb amputations, movements of the stump, the normal hand, and the missing arm were studied. In a third patient with both legs amputated, movements of the stumps and of the missing feet were studied. The fMRI data were analyzed with the Statistical Parametric Map 96 software and reformatted for integration into anatomic slices.

RESULTS

Virtual movements of the missing limbs produced contralateral primary sensorimotor cortex and central sulcus activations in the patients with upper-limb amputation. Interhemispheric and bilateral activations were found in the patient with both legs amputated. These activation areas were different from the stump activation areas. Additionally, the significance thresholds chosen to generate the activation maps in virtual movements (although individual) were globally the same as those used to detect motor activation in the normal side of the patients.

CONCLUSION

Cortical areas devoted to the missing limb seem to persist for several years after amputation. The precentral activations found in our patients are in agreement with the statement that the neural mechanisms involved in the mental representation of an action and in its execution are the same. Data from fMRI can be used to evaluate phantom limb virtual movements and to study cortical reorganization phenomena that can appear with time or as a result of some therapies. In these patients, fMRI data may be useful in assisting the neurosurgeon in the placement of chronic motor cortex electrodes.

A new method for encapsulation of living cells: preliminary results with PC12 cell line

A new method is described for encapsulation of living cells. PC12 rat adrenal pheochromocytoma cells, which have been shown to synthesize, store and release dopamine were employed. The particles are made first and the cells then incorporated in a gentle mechanical procedure. The morphology (by light and electron microscopic observation), stability, rheology, texture and permeability of these microcapsules provided by Kappa Biotech were investigated. Membrane permeability studies demonstrated exclusion of 69,000 Da human serum albumin, but equilibrium of D-glucose and inulin was within 24h, indicating a molecular weight cut-off in the 5000-70,000 Da range. The viability and the function of the encapsulated cells were evaluated by measuring the spontaneous release of dopamine by high performance liquid chromatography with electrochemical detection. The results show that dopamine-secreting cells can be sequestered in a semi-permeable capsule and still display good viability and proliferation for at least 1 month.

Chronic motor cortex stimulation for phantom limb pain: a functional magnetic resonance imaging study: technical case report

OBJECTIVE AND IMPORTANCE

Chronic motor cortex stimulation has provided satisfactory control of pain in patients with central or neuropathic trigeminal pain. We used this technique in a patient who experienced phantom limb pain. Functional magnetic resonance imaging (fMRI) was used to guide electrode placement and to assist in understanding the control mechanisms involved in phantom limb pain.

CLINICAL PRESENTATION

A 45-year-old man whose right arm had been amputated 2 years previously experienced phantom limb pain and phantom limb phenomena, described as the apparent possibility of moving the amputated hand voluntarily. He was treated with chronic motor cortex stimulation.

INTERVENTION

Data from fMRI were used pre- and postoperatively to detect shoulder and stump cortical activated areas and the "virtual" amputated hand cortical area. These sites of preoperative fMRI activation were integrated in an infrared-based frameless stereotactic device for surgical planning. Phantom limb virtual finger movement caused contralateral primary motor cortex activation. Satisfactory pain control was obtained; a 70% reduction in the phantom limb pain was achieved on a visual analog scale. Postoperatively and under chronic stimulation, inhibiting effects on the primary sensorimotor cortex as well as on the contralateral primary motor and sensitive cortices were detected by fMRI studies.

CONCLUSION

Chronic motor cortex stimulation can be used to relieve phantom limb pain and phantom limb phenomena. Integrated by an infrared-based frameless stereotactic device, fMRI data are useful in assisting the neurosurgeon in electrode placement for this indication. Pain control mechanisms and cortical reorganization phenomena can be studied by the use of fMRI.

[Management of intractable cancer pain: from intrathecal morphine to cell allograft]

The durable effectiveness of intrathecal morphine administration is well established for the management of intractable cancer pain, after failure of systemic opioids, secondary to the persistence of non-reversible undesirable side effects. Many patients are referred to late in the disease course. This conservative method to control pain of malignant origin must not be reserved for last resort treatment for terminal patients. Intra-cerebro-ventricular morphine administration is a very effective and generally safe method for controlling intractable cancer pain. Because of the chronic implantation of an intra-ventricular catheter this method is somewhat invasive. Its indications remain a simple and effective alternative when the topography of nociceptive pain is diffuse or cephalic. In clinical practice, intrathecal and/or intra-cerebro-ventricular administration of opioids is limited by cost, the need for specialized maintenance and mechanical malfunctions if implantable drug delivery systems, or by the risk of bacterial contamination and ambulatory constraints when repeated daily injections via an intrathecal access port are used. To answer these limitations, cell therapy using intrathecal chromaffin cell allograft is a promising approach for the management of cancer pain refractory to traditional drug therapy and pain lesion surgery. The basic rationale and preclinical studies on experimental pain models have enabled starting prospective clinical trials. Prior to transplantation, handling and preparation of the chromaffin tissue is critical for allograft viability. The initial results of clinical trials with human chromaffin cell grafts from intractable cancer pain have reported long-lasting pain relief, in correlation with met-enkephalin release into the CSF. Convincing evidence will require controlled studies. The limitations of this innovative cell therapy and especially the lack of human adrenal gland availability point to the need for new sources of cells. Perspectives include xenogenic or engineered cell lines.

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.

[Clinical perspectives of xenografts: encapsulated chromaffin cells and pain]

Intrathecal allograft of chromaffin cells can be effectively used in replacement of more conventional therapies for treating intractable chronic pain, such as in cancer. The efficacy of this technique depends on the ability of those cells to produce analgesic opioids and on the immuno-privileged property of the central nervous system, in which rejection risks are limited. However, there are some limitations to the generalization of this new therapy, mainly due to the low number of available grafts. Thus other sources than humans have to be considered. Here we discuss the pros and cons of the xenogeneic chromaffin cells of bovine or porcine origin. Graft immuno-isolation, for example, by using cell encapsulation, seems to be unavoidable in spite of the graft site.

Intrathecal grafting of unencapsulated adrenal medullary tissue can bring CD4 T lymphocytes into CSF: a potentially deleterious event for the graft

Adrenal medullary tissue including chromaffin cells was grafted intrathecally in cancer patients to relieve intractable pain. The central nervous system (CNS) is considered an immune privileged site. Therefore, non-HLA-matched and unencapsulated tissue was grafted in 15 patients and 1 sham control in a series of at least 20 grafts. We observed an increase in CSF lymphocyte counts in 15/20 allografts (75%). In contrast to peripheral blood, CD4 T cells predominated in the CSF, but failed to exhibit an activated phenotype (CD25+ CD45RO+ HLA-DR+). The positive effect of graft on pain, the high met-enkephalin levels, the absence of any increase in CSF cytokine levels particularly for IFN-gamma or IL-2 (but not IL-10 and IL-6), indirectly indicated that the graft was tolerated despite the presence of CSF lymphocytes. The single treatment failure and three of four cases of partial efficacy occurred in grafts where CSF lymphocytes were present. Moreover, when assayed (n = 7), the CD4+ CSF lymphocytes still retained the capacity to exhibit ex vivo a normal or enhanced frequency of T CD4 cells producing IFN-gamma and IL-2. Taken together, our observations indicate that impairment of the local immunosuppressive balance can lead to activation of those CSF CD4 T cells and drive a rejection process. This study suggests further work on the purification and/or the immunoisolation of tissues grafted in the CNS will be necessary, particularly when the possibility of long-term and repeated grafting is considered.

Computer-generated surgical simulation of morphological changes in microstructures: concepts of “virtual retractor”

The author's goal was to develop a computer graphics model to simulate the displacement and morphological changes that are caused by the retraction of fine intracranial structures.

The authors developed an application program to interpolate the contour of models of an artery and a retractor. The center of the displacement was determined by spatial coordinates, and the shape of the displacement of the arterial model was calculated by using a cosine-based formula with representation of a brain retractor. This computer graphics model was applied to the simulation of the displacement and morphological changes that occur when retraction is performed in the optic nerve. An illustrative case is presented, in which the optic nerve was displaced by a retractor to simulate the surgery performed in a carotid cave aneurysm of the internal carotid artery.

The authors have named this methodological tool “virtual retractor.” This new navigational system for open microneurosurgery would be useful in teaching surgical microanatomy and in presurgical operative planning.

Effect of gamma knife on secondary trigeminal neuralgia

The following study was conducted to evaluate the results of Gamma Knife stereotactic radiosurgery in the management of secondary trigeminal neuralgia. 53 patients suffering from secondary trigeminal neuralgia were studied and the results reported. We defined four therapeutic groups: group I correspond to essential trigeminal neuralgia. The primary aim was tumor control in group IV and pain cessation in group III and II (visualization of the fifth nerve root was possible in group II but not in group III). The target dose of the radiosurgery used in the current study varied from 20 to 40 Gy in group III and IV and from 70 to 90 Gy in group I and II. At short-term follow-up, 37 patients (74%) were pain-free, 9 patients (18%) were improved (50%-90% relief) and only 4 patients (8%) experienced treatment failure. Among the patients with early treatment success, 10 patients experienced a complete recurrence of pain in the four succeeding years, and 11 initially pain-free patients deteriorated to partial pain relief. The median time to pain relief was three months (range 1 day to 1 year). The mean follow-up was 32 months (range 7 to 60 months). No patient developed increased facial pain or deafferentation pain. Among the 53 patients, only two exhibit a slight facial hypesthesia and one patient described motor fasciculation related to Gamma Knife treatment. In our experience Gamma Knife surgery appears a safe and effective method for the treatment of secondary trigeminal neuralgia.

Hearing restoration in posterior fossa tumors

OBJECTIVE

This study aimed to assess the results of hearing restoration with a cochlear or a brainstem implant in posterior fossa tumors.

PATIENTS

Six patients were selected. Two patients with an acoustic neuroma in the only-hearing ear (cases 1 and 2), one patient with a posterior fossa meningioma (case 3), one patient with bilateral facial neuroma (case 4), and two patients with bilateral acoustic neuroma (cases 5 and 6) participated.

INTERVENTION

In cases 1 and 2, the patients had a cochlear implant inserted on the only-hearing ear opposite the acoustic neuroma. In case 3, the patient presented with total deafness on the left side and a 10-mm meningioma on the right side. A cochlear implantation was performed after removal of the meningioma on the right side. In case 4, the patient was operated on on both sides with bilateral postoperative deafness. A cochlear implantation was performed on the better hearing ear. In cases 5 and 6, patients underwent an auditory brainstem implantation after the exeresis of the second tumor.

RESULTS

Promontory test results were positive for patients 1, 2, 3, and 4. After implantation, patients 1, 2, 3, and 4 scored 98%, 13%, 70%, and 30%, respectively, in open-set sentence recognition tests, whereas patients 5 and 6 scored 0% and 20%, respectively.

CONCLUSIONS

In case of nonfunctional cochlear nerve, in acoustic neuroma, either bilateral and in the only-hearing ear, promontory test should be performed. If positive results, a cochlear implantation should be performed, because successful results could be expected. Overall results of cochlear implantation on speech discrimination are better than those obtained with a brainstem implant.

[Treatment of spasticity with the intrathecal administration of baclofen]

Direct intrathecal administration of baclofen in the treatment of severe spasticity was proposed in 1984 by Richard Penn with the objective to carry out a selective spinal distribution of the active principle thus avoiding supraspinal side effects. We presented our first results at the French Language Association of Neurosurgery in 1985 within the framework of a report on "Functional neurosurgery of cerebral palsy" (Neurochirurgie, 1985, 31 (suppl 1): 1-118). This study aims to specify the selection criteria and current indications of this method for the treatment of severe chronic diffused spasticity of spinal and cerebral origin in adults and in children. This report relates to our experience concerning 60 patients (10 children) that benefit from the use of a totally implantable system for chronic administration. The total follow-up of all patients was 48 months (from 3 to 140 months). The initial effective daily amount of baclofen was 156 micrograms/24 hours and progressed in time to reach in the long run 280 micrograms/24 hours, with a very broad interindividual variability from 36 to 1050 micrograms/24 hours. All the patients benefited from a reduction in muscular hypertonicity as well as painful muscular spasms. On the other hand, the functional improvement was very variable from one patient to another and depended primarily on the initial clinical state and the etiology of the spasticity. The results observed were more significant in post-traumatic paraplegia than those secondary to demyelination disease even if they were stabilized with regard to spasticity of spinal origin. This mode of administration currently plays a significant role in the treatment of spasticity of cerebral origin, in particular in children presenting a motor disorder of cerebral origin with spastic prevalence. The current limitations of this type of treatment are technical because of the frequent catheter malfunctions, but are due essentially to the importance and constraint of the multi-disciplinary organization needed for the out-patient follow-up.

Does intrathecal morphine in the treatment of cancer pain induce the development of tolerance?

OBJECTIVE

This retrospective study was designed to investigate whether chronic lumbar intrathecal administration of morphine leads to the development of opioid tolerance in patients suffering from intractable cancer pain.

METHODS

Between 1978 and 1995, 159 patients with refractory cancer pain were treated with intrathecal morphine in our Multidisciplinary Pain Center. The treatment consisted of preservative-free morphine administered through an access port as a single bolus. In this series of patients (n = 159), the daily doses of intrathecal morphine were determined as a function of duration of follow-up.

RESULTS

The mean follow-up period was 95 days (range, 5-909 d), the mean starting daily dose of intrathecal morphine was 2.69 mg (range, 1-7.5 mg), and the mean terminal dose was 7.82 mg (range, 1-80 mg). The results demonstrated that only a moderate increase in daily dose of intrathecal morphine was required during the course of treatment (a two- to threefold increase for a 3-mo period). Furthermore, the dose increment was similar for patients followed up for more or less than 60 days. This increase did not result in any central opioid-related side effects, and the pain was managed satisfactorily.

CONCLUSION

The requirement for a moderate increase in intrathecal opioid doses reflects the development of tolerance but did not limit the patients' ability to obtain adequate analgesia during the course of their painful disease.

Relief of intractable cancer pain by human chromaffin cell transplants: experience at two medical centers

In addition to its possible role as a replacement source in CNS degenerative diseases, neural transplantation may be used to augment the normal production of neuroactive substances. Our laboratory at the University of Illinois at Chicago has shown, in both acute and chronic pain models, that transplantation of adrenal medullary tissue or isolated chromaffin cells into CNS pain modulatory regions can reduce pain sensitivity in rodents. Chromaffin cells were chosen as the donor source since they produce high levels of both opioid peptides and catecholamines, substances which reduce pain sensitivity when injected locally into the spinal subarachnoid space. The analgesia produced by these transplants probably results from the release of both opioid peptides and catecholamines since it can be blocked or attenuated by both opiate and adrenergic antagonists. Studies indicate that even over long periods there is no apparent development of tolerance. Promising results have been obtained in preliminary clinical studies using allografts of adrenal medulla to relieve cancer pain. This clinical review encompasses results at two Medical Centers-University of Illinois at Chicago and University Paul Sabatier, Toulouse, France-in assessing efficacy of subarachnoid adrenal medullary transplantation for alleviating cancer pain. Our clinical and autopsy data strongly support our previous laboratory studies, i.e., that chromaffin cell transplants into the subarachnoid space represent a promising new approach to the alleviation of chronic pain. It is suggested that further clinical studies are now warranted.

Oxytocin increases thresholds of colonic visceral perception in patients with irritable bowel syndrome

AIM

The effects of oxytocin on colonic perception of intraluminal distension were evaluated in 26 patients with irritable bowel syndrome (IBS), using a flaccid bag placed in the descending colon and connected to a computerised barostat.

METHOD

Symptomatic responses (first sensation and pain) were evaluated during isobaric distensions (4 mm Hg increments, five minute duration, five minute interval with return to zero pressure between each step), performed automatically by the barostat, during a continuous infusion of placebo or various doses of oxytocin (10, 20, 30, and 50 mU/min).

RESULTS

The distension pressure (mean (SD)) required to induce a first abdominal sensation was 17.3 (5.5) mm Hg on placebo, 19.9 (5.8) on oxytocin 10 mU/min (NS), 22.3 (6.0) mm Hg on oxytocin 20 mU/min (p < 0.01), 23.1 (6.6) mm Hg on oxytocin 30 mU/min (p < 0.01), and 24.0 (7.1) mm Hg on oxytocin 50 mU/min (p < 0.01). The distension pressure required to induce pain was 24.8 (6.3) mm Hg on placebo, 26.0 (5.8) on oxytocin 10 mU/min (NS), 33.3 (7.8) mm Hg on oxytocin 20 mU/min (p < 0.01), 34.2 (7.6) mm Hg on oxytocin 30 mU/min (p < 0.01), and 34.3 (7.9) mm Hg on oxytocin 50 mU/ min (p < 0.01). Compliance curves were not different after placebo and oxytocin injection at the different doses. Naloxone did not inhibit the effect of oxytocin. Oxytocin also did not alter somatic perception, characterised by the RIII reflex at the level of the biceps femori.

CONCLUSIONS

Oxytocin significantly increases thresholds for visceral perception in IBS patients at doses equal or to greater than 20 mU/min, possibly by acting at the level of visceral afferents.

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.

CSF baclofen levels after intrathecal administration in severe spasticity

The pharmacokinetic parameters in the CSF of baclofen given to 4 patients as an intrathecal bolus are reported. Considerable inter-individual variability in the parameters was observed. The elimination half-life ranged from 0.9 to 5 h and the clearance from 0.013 to 0.08 l.h-1. In order to optimize treatment, it is suggested that CSF baclofen levels be matched to changes in Hoffman's monosynaptic reflex (H reflex).

Chronic intrathecal baclofen administration for control of severe spasticity

Baclofen, the most effective drug for treating spasticity, is a specific agonist of gamma-aminobutyric acid-B receptors, and is very abundant in the superficial layers of the spinal cord. Given orally, baclofen does not easily penetrate the blood-brain barrier, and is distributed equally to the brain and spinal cord. Direct intrathecal administration was given in order to change the distribution of the drug by preferentially perfusing the spinal cord. Eighteen patients presenting a severe spastic syndrome were treated with chronic intrathecal infusion of baclofen in the lumbar cerebrospinal fluid. After clinical preselection, 38 patients were implanted with a lumbar access port allowing long-term trials in order to determine the efficacy of baclofen therapy and the effective 12-hour dose. The 18 patients selected for chronic administration were implanted with a programmable pump. The pathology in these cases was: multiple sclerosis (6 cases), posttrauma spastic syndrome (eight cases), and (one case each) cerebral palsy, ischemic cerebral lesion, spinal ischemia, and transverse myelitis. The mean follow-up period was 18 months (range 4 to 43 months). The clinical results were evaluated according to muscular hypertony on Ashworth's scale (changed for occurrence of painful spasms) and functional improvement. Results were better for spastic syndrome secondary to traumatic medullary lesion than for demyelinating disease. Hypertonia was improved in all cases as confirmed by the registration of the Hoffman (H) reflex. Painful muscular spasms disappeared in 14 of the 16 affected patients. Significant functional improvement was noted in nine patients and was considerable in three. The risk of side effects secondary to overdose (such as excessive hypotonia or central depression) and the absence of a specific baclofen antagonist stresses the necessity for accurate determination of the efficient dose. After an initial titration period and adjustment of the therapeutic dose, the individual doses were from 21 to 500 micrograms/24 hrs (mean 160 micrograms/24 hrs). This new conservative method is very effective, perfectly reversible, and safe when administered in conditions favorable to its use.