Encapsulated cell device approach for combined electrical stimulation and neurotrophic treatment of the deaf cochlea.

Profound hearing impairment can be overcome by electrical stimulation (ES) of spiral ganglion neurons (SGNs) via a cochlear implant (CI). Thus, SGN survival is critical for CI efficacy. Application of glial cell line-derived neurotrophic factor (GDNF) has been shown to reduce SGN degeneration following deafness. We tested a novel method for local, continuous GDNF-delivery in combination with ES via a CI. The encapsulated cell (EC) device contained a human ARPE-19 cell-line, genetically engineered for secretion of GDNF. In vitro, GDNF delivery was stable during ES delivered via a CI. In the chronic in vivo part, cats were systemically deafened and unilaterally implanted into the scala tympani with a CI and an EC device, which they wore for six months. The implantation of control devices (same cell-line not producing GDNF) had no negative effect on SGN survival. GDNF application without ES led to an unexpected reduction in SGN survival, however, the combination of GDNF with initial, short-term ES resulted in a significant protection of SGNs. A tight fibrous tissue formation in the scala tympani of the GDNF-only group is thought to be responsible for the increased SGN degeneration, due to mechanisms related to an aggravated foreign body response. Furthermore, the fibrotic encapsulation of the EC device led to cell death or cessation of GDNF release within the EC device during the six months in vivo. In both in vitro and in vivo, fibrosis was reduced by CI stimulation, enabling the neuroprotective effect of the combined treatment. Thus, fibrous tissue growth limits treatment possibilities with an EC device. For a stable and successful long-term neurotrophic treatment of the SGN via EC devices in human CI users, it would be necessary to make changes in the treatment approach (provision of anti-inflammatories), the EC device surface (reduced cell adhesion) and the ES (initiation prior to fibrosis formation).

Increased encapsulated cell biodelivery of nerve growth factor in the brain by transposon-mediated gene transfer.

Nerve growth factor (NGF) is a potential therapeutic agent for Alzheimer's disease (AD) as it has positive effects on the basal forebrain cholinergic neurons whose degeneration correlates with the cognitive decline in AD. We have previously described an encapsulated cell biodelivery device, NsG0202, capable of local delivery of NGF by a genetically modified human cell line, NGC-0295. The NsG0202 devices have shown promising safety and therapeutic results in a small phase 1b clinical study. However, results also show that the NGF dose could advantageously be increased. We have used the sleeping beauty transposon expression technology to establish a new clinical grade cell line, NGC0211, with at least 10 times higher NGF production than that of NGC-0295. To test whether encapsulation of this cell line provides a relevant dose escalation step in delivering NGF for treatment of the cognitive decline in AD patients, we have validated the bioactivity of devices with NGC0211 and NGC-0295 cells in normal rat striatum as well as in the quinolinic acid striatal lesion model. These preclinical animal studies show that implantation of devices with NGC0211 cells lead to significantly higher NGF output, which in both cases correlate with highly improved potency.

Generation of regionally specified neurons in expanded glial cultures derived from the mouse and human lateral ganglionic eminence.

The specific identity of neuronal precursors within the embryonic brain is, at present, not clear. Here we show that cultures with glial characteristics derived from the embryonic mouse or human lateral ganglionic eminence (LGE) can be expanded over many passages and maintain their glial identity. Interestingly, removal of serum and EGF from the culture medium results in the generation of large numbers of neurons. The neurons derived from these cultures display many characteristic features of striatal neurons, which normally derive from the LGE, even after extensive expansion in vitro. Furthermore, a portion of the neurons generated in these cultures were shown to arise from glial fibrillary acidic protein (GFAP)-expressing cells. These results demonstrate that at least a subpopulation of neurogenic LGE precursors exhibit glial characteristics.

Implantation of bioactive growth factor-secreting rods enhances fetal dopaminergic graft survival, outgrowth density, and functional recovery in a rat model of Parkinson's disease.

One of the drawbacks with fetal ventral mesencephalic (VM) grafts in Parkinson's disease is the limited outgrowth into the host striatum. In order to enhance graft outgrowth, epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) were administered by implantation of bioactive rods to the lateral part of the striatum to support grafted fetal VM implanted to the medial portion of the striatum. The polymer-based bioactive rods allow for a local secretion of neurotrophic factors over a time period of approximately 2 weeks. Moreover, glial cell line-derived neurotrophic factor (GDNF) and transforming growth factor-beta1 (TGFbeta1) were administered using the same technique. Concomitant administration of GDNF and TGFbeta1 was achieved by insertion of one GDNF and one TGFbeta1 rod. This was performed to investigate possible additive effects between GDNF and TGFbeta1. Rotational behavior, outgrowth from and nerve fiber density within the VM graft, and the number of TH-positive cells were studied. Functional compensation by reduction of rotational behavior was significantly enhanced in animals carrying bFGF and GDNF rods in comparison with animals carrying only VM graft. EGF and bFGF significantly increased the innervation density. Moreover, the nerve fiber density within the grafts was significantly enhanced by bFGF. Cell counts showed that a significantly higher number of TH-positive neurons was found in grafts treated with bFGF than that found in GDNF-treated grafts. An additive effect of TGFbeta1 and GDNF was not detectable. These results suggest that bioactive rods is a useful tool to deliver neurotrophic factors into the brain, and since bFGF was a potent factor concerning both functional, immunohistochemical and cell survival results, it might be of interest to use bFGF-secreting rods for enhancing the overall outcome of VM grafts into patients suffering from Parkinson's disease.

In vitro expansion of a multipotent population of human neural progenitor cells.

The isolation and expansion of human neural progenitor cells have important potential clinical applications, because these cells may be used as graft material in cell therapies to regenerate tissue and/or function in patients with central nervous system (CNS) disorders. This paper describes a continuously dividing multipotent population of progenitor cells in the human embryonic forebrain that can be propagated in vitro. These cells can be maintained and expanded using a serum-free defined medium containing basic fibroblast growth factor (bFGF), leukemia inhibitory factor (LIF), and epidermal growth factor (EGF). Using these three factors, the cell cultures expand and remain multipotent for at least 1 year in vitro. This period of expansion results in a 10(7)-fold increase of this heterogeneous population of cells. Upon differentiation, they form neurons, astrocytes, and oligodendrocytes, the three main phenotypes in the CNS. Moreover, GABA-immunoreactive and tyrosine hydroxylase-immunoreactive neurons can be identified. These results demonstrate the feasibility of long-term in vitro expansion of human neural progenitor cells. The advantages of such a population of neural precursors for allogeneic transplantation include the ability to provide an expandable, well-characterized, defined cell source which can form specific neuronal or glial subtypes.

Artificial neural network-aided image analysis system for cell counting.

BACKGROUND: In histological preparations containing debris and synthetic materials, it is difficult to automate cell counting using standard image analysis tools, i.e., systems that rely on boundary contours, histogram thresholding, etc. In an attempt to mimic manual cell recognition, an automated cell counter was constructed using a combination of artificial intelligence and standard image analysis methods. METHODS: Artificial neural network (ANN) methods were applied on digitized microscopy fields without pre-ANN feature extraction. A three-layer feed-forward network with extensive weight sharing in the first hidden layer was employed and trained on 1,830 examples using the error back-propagation algorithm on a Power Macintosh 7300/180 desktop computer. The optimal number of hidden neurons was determined and the trained system was validated by comparison with blinded human counts. System performance at 50x and lO0x magnification was evaluated. RESULTS: The correlation index at 100x magnification neared person-to-person variability, while 50x magnification was not useful. The system was approximately six times faster than an experienced human. CONCLUSIONS: ANN-based automated cell counting in noisy histological preparations is feasible. Consistent histology and computer power are crucial for system performance. The system provides several benefits, such as speed of analysis and consistency, and frees up personnel for other tasks.

Interactions between human embryonic forebrain cells and the cytokines interferon-gamma and interleukin-4.

In the present study we investigated the capacity of human first trimester forebrain cells at different gestational ages to produce IFN-gamma and IL-4. We also studied the effects of IFN-gamma on their proliferation, survival and expression of MHC antigens. IFN-gamma but not IL-4 was spontaneously produced after 24 h cultures. Furthermore, IFN-gamma exhibited anti-proliferative effects and induced MHC expression on these cells. However, the IFN-gamma exposed cultures showed significantly higher cell survival compared to un-exposed cultures. Co-culture with IL-4 blocked the IFN-gamma production and reversed its anti-proliferative effects. These interactions suggest important roles for cytokines in the survival, proliferation and differentiation of human embryonic and fetal forebrain cells.

Elevated cytotoxicity in combat veterans with long-term post-traumatic stress disorder: preliminary observations.

Resting immune [WBC and differential cell counts lymphocyte phenotyping (CD2, CD4, CD8, CD16, CD20, and CD56), and NK activity] and endocrine (cortisol, prolactin, growth hormone, and DHEA-SO4) parameters were measured in 10 male, Vietnam combat veterans diagnosed with long-term post-traumatic stress disorder (PTSD) and 9 control Vietnam combat veterans without a PTSD diagnosis but with a comparable history of alcohol abuse. Subjects completed a battery of psychological questionnaires. We report on preliminary observations of the relationship between PTSD and physiological and psychological parameters. With some important exceptions, PTSD patients did not differ from the age-matched control group with regard to hormone levels or lymphocyte phenotypes. However, NK activity was higher in the PTSD population than in the controls. Beck, Mississippi, and Combat Exposure scores were significantly elevated in the PTSD population. In contrast to previous observations in depressed populations, depression (indicated by elevated Beck scores), comorbid with PTSD, was associated with increased natural cytotoxicity.

Unexpected in vitro chemosensitivity of malignant gliomas to 4-hydroxyperoxycyclophosphamide (4-HC).

To individually tailor chemotherapy for patients with malignant gliomas according to tumor chemosensitivity, a rapid assay system which can be performed with a high success rate is needed. The fluorescent cytoprint assay (FCA) can assess multiple chemotherapeutic agents using small (approximately 500 cells) tumor aggregates very quickly (approximately 1 wk). Tissue samples from 51 patients with malignant gliomas obtained either at time of initial diagnosis (n = 34) or at recurrence were assayed using this method. The assay success rate approached 90% in those culture samples which were histologically verified as tumor. A meaningful number of agents could be tested both on samples obtained by stereotactic biopsy (median, 5) and on specimens from more extensive resections (median, 6). One hundred ninety-three FCAs were performed on a samples obtained from 36 patients. In only twenty six assays (14%) was an agent deemed sensitive (> 90% cell kill) to a chemotherapeutic agent. Sixty-two percent of sensitive FCAs were observed in tumors tested against the activated analog of cyclophosphamide, 4-hydroxyperoxycyclophosphamide (4-HC), where a sensitivity rate (# samples sensitive/total tested against agent) of 64% (95 % CI, 36.6-77.9%) was noted. This rate was significantly higher than with any other agent tested (p = 0.012, two sided McNemar's test) and was not affected by age, histology or disease status. We conclude that: (1) the FCA represents a feasible method for quickly assaying tumors for sensitivity to multiple chemotherapeutic agents; and (ii) malignant gliomas may be particularly sensitive to 4-HC.

First trimester development of the human nigrostriatal dopamine system.

The aim of the present study was to characterize the morphological and neurochemical differentiation of mesencephalic dopaminergic neurons in human embryos, derived from elective first trimester abortions. Embryonic brain tissue was taken for analysis of tyrosine hydroxylase (TH) by immunohistochemistry and Western blot, and for analysis of endogenous dopamine (A) content using HPLC-ED. TH expression was first detected at 3.5 weeks of gestational age (Carnegie stage 11) by immunohistochemical staining of the primordial sympathetic trunk along both sides of the neural tube. In sagittal sections of the intact 4.5-week-old embryo, a small, distinct population of rounded, densely packed TH-immunoreactive perikarya with short primary processes was seen in the midbrain. During the latter half of the first trimester, the number of TH-stained cells as well as the length and number of axonal processes projecting toward and into the developing neostriatum increased rapidly. At the end of the first trimester, varicose fibers could be detected in the striatal anlage. In order to verify that TH was the antigen recognized by the antibodies used for immunohistochemistry on human tissue specimens, mesencephalic tissue of 5-10 weeks gestation was analyzed by Western blot technique. A single, homogeneous band with the apparent molecular weight of approximately 60 kDa was clearly detected at 5 weeks of age. The amount of TH/mg total protein increased at least 10-fold between 5-10 weeks of gestation. For comparison, the mesencephalon and the forebrain/basal ganglia were analyzed for endogenous DA content using HPLC-ED. DA was first detected at 5.5 weeks of gestational age in both mid- and forebrain, and DA levels were found to increase exponentially from 7 to 7.5 weeks of age, reaching 4-5.5 ng DA/mesencephalon and 50-75 ng DA/g caudate nucleus-putamen anlage at the end of the first trimester. Together, morphological and biochemical data presented here constitute evidence for a very early appearance, migration, and differentiation as well as functional development of human mesencephalic dopaminergic neurons and their projections into target areas during the first trimester.

A randomized, blinded, placebo-controlled trial of divalproex sodium prophylaxis in adults with newly diagnosed brain tumors.

BACKGROUND: Seizures occur after the diagnosis of brain tumors in up to 40% of patients. Prophylactic anticonvulsants are widely advocated despite a lack of convincing evidence of their efficacy in preventing first seizures. We conducted a randomized, double-blind, placebo-controlled study comparing the incidence of first seizures in divalproex sodium- and placebo-treated patients with newly diagnosed brain tumors. PATIENTS AND METHODS: Patients who had not previously had a seizure were randomized within 14 days of diagnosis of their brain tumor to receive either divalproex sodium or placebo. All patients had at least one supratentorial brain lesion, a Karnofsky Performance Score (KPS) > or = 50%, and no previous anticonvulsant use or other brain disease. Compliance and adequacy of dosing were assessed by pill counts and monthly blood levels. RESULTS: Seventy-four of 75 consecutive eligible patients were entered in this study. Median follow-up was 7 months. The drug and placebo groups did not differ significantly in age, sex, KPS, primary tumor type, number or location of brain lesions, frequency of brain surgery, or pretreatment EEG. Thirteen of 37 patients (35%) receiving divalproex sodium and 9 of 37 patients (24%) on placebo had seizures. The odds ratio for a seizure in the divalproex sodium arm relative to the placebo arm was 1.7 (95% CI 0.6 to 4.6; p = 0.3). The hypothesis that anticonvulsant prophylaxis provides a reduction in the frequency of first seizure as small as 30% was rejected (p = 0.05). CONCLUSIONS: Anticonvulsant prophylaxis with divalproex sodium is not indicated for patients with brain tumors who have not had seizures.

Polymeric controlled-release amsacrine chemotherapy in an experimental glioma model.

The purpose of this study was to fabricate and investigate amsacrine containing polymeric rods for use in interstitial chemotherapy of malignant glioma. Ethylene vinyl acetate copolymer (EVAc) rods containing 40% amsacrine (AMSA) were fabricated successfully with an extrusion method. In vitro kinetic studies revealed a high level of reproducibility of the production process. The release of AMSA showed a biphasic pattern consistent with a matrix-type controlled-release system with an initial more rapid release rate followed by a slower and more linear release phase. Release of AMSA was observed for over 6 months and the rods continue to release in a stable fashion. In vitro studies using rat glioma (RG2) in cell culture showed that cells treated with AMSA released from the rods were killed in a dose dependent manner indicating that AMSA incorporated into the polymer remained biologically active. In vivo studies of rats with single AMSA rods implanted five days after RG2 tumour implantation revealed histological evidence of an anti-tumour effect as well as an increased survival (p < 0.0003). The mean survival of the amsacrine treated rats was 78 days with 50% still remaining alive > 5 months after implantation. All control animals developed tumours and died within 15-19 days after tumour implantation (mean = 17 days). Amsacrine implanted animals showed no significant histological or clinical evidence of toxicity. We conclude that amsacrine containing EVAc rods can be safely and efficaciously use against the RG2 experimental glioma in a rat model and warrant further investigation.

Paclitaxel disposition in plasma and central nervous systems of humans and rats with brain tumors.

BACKGROUND: Paclitaxel (Taxol) has been shown to sensitize some malignant cells to the effects of radiation. A number of clinical protocols, combining paclitaxel with radiation therapy, have been designed to exploit this phenomenon. The radiation-potentiating effect of paclitaxel is likely dependent on the ability of the drug to penetrate the tissue being radiated. Paclitaxel is known to have limited access to the central nervous system (CNS) of rats and mice, but its ability to penetrate malignant tissue in the CNS is inadequately documented. PURPOSE: Our purpose was to examine the concentrations of paclitaxel in the cerebrospinal fluid (CSF) of patients with CNS malignancies and in normal and malignant tissues from the brains of Fischer rats bearing the C6 rat glioma and then to compare those paclitaxel concentrations with concomitant paclitaxel concentrations in the plasma of those same patients and animals. METHODS: Four patients were treated with 3-hour infusions of paclitaxel at doses between 90 and 200 mg/m2. Plasma and CSF were sampled at 0.33, 1.5, 3.25, 5, 6, and 24 hours after initiation of the paclitaxel infusion. Four Fischer rats had 20,000 C6 glioma cells stereotactically implanted into their right frontal lobes; 28 days later, they were given 3-hour infusions of paclitaxel at 10 mg/kg. Plasma was sampled during the paclitaxel infusion. At the completion of the infusion, rats were killed, and portions of their normal and malignant CNS tissues were removed for histologic assessment. Concentrations of paclitaxel in plasma, CSF, and brain tissue were determined with high-pressure liquid chromatography. RESULTS: Plasma pharmacokinetics of paclitaxel in patients with brain tumors were comparable to those previously described in patients with other malignancies. Paclitaxel could be measured in CSF of all patients, but concentrations were very low. Peak paclitaxel concentrations in CSF ranged between 5 and 83 nM and occurred between 3.25 and 5 hours after initiation of the paclitaxel infusion. Peak paclitaxel concentrations in CSF were between 0.12% and 8.3% of those present in concomitant plasma samples. Paclitaxel was not detectable in the normal or malignant CNS tissue of any rat, despite the fact that plasma concentrations of paclitaxel at the time of tissue acquisition ranged from 0.62 to 153 microM. CONCLUSIONS: Paclitaxel has only limited access to the CSF of patients with CNS malignancies and to normal and malignant CNS tissues of rats bearing brain tumors. IMPLICATIONS: The utility of combining paclitaxel with radiation therapy to treat CNS malignancies should be considered in light of the documented limited access of paclitaxel to the CNS.

Diagnosis, management, and survival of patients with leptomeningeal cancer based on cerebrospinal fluid-flow status.

BACKGROUND: The authors assessed cerebrospinal fluid (CSF) flow in patients with carcinomatous meningitis using technetium-99m-DTPA (Tc-99) ventriculography to determine the frequency of flow abnormalities, their reversibility with treatment, and the implications for successful therapy and survival. METHODS: Technetium-99m-DTPA flow studies were performed in 31 patients after placement of Ommaya reservoirs (Baxter, McGaw Park, IL). Two millicuries of Tc-99 were injected into the reservoir. Planar images of the head and entire spine were obtained after 10 and 30 minutes and after 1, 4, 6, and 24 hours. Follow-up studies were performed for 12 patients whose initial studies were abnormal or who developed complications of therapy. RESULTS: In 19 of the 31 patients (61%), ventricular-outlet, spinal, or convexity blocks were identified. In 11 of these 19 patients, focal radiotherapy to the site of the block restored normal flow. Survival among patients with initially normal, abnormal but correctable, and abnormal but uncorrectable CSF flow differed significantly (6.9, 13.0, and 0.7 months respectively; P < 0.001). Some patients who were treated intrathecally despite abnormal CSF flow experienced drug-related toxicity. CONCLUSIONS: Cerebrospinal fluid-flow blocks are common in patients with carcinomatous meningitis and may occur at the skull base, in the spinal canal, and over the convexities. These flow abnormalities often can be corrected with appropriately directed radiotherapy. If untreated, CSF tumor progression (protected site effect), neurotoxicity (high concentration effect), and systemic toxicity (reservoir effect) can occur, resulting in shortened survival and treatment-related morbidity. Therefore, intrathecal chemotherapy should be preceded by a radionuclide flow study and should be delayed if abnormal flow is documented until appropriate radiotherapy reestablishes normal flow.

Intrinsic and extrinsic characteristics of human tumors relevant to radiosurgery: comparative cellular radiosensitivity and hypoxic percentages.

UNLABELLED: We have collected the in vitro x-ray radiation survival characteristics of 181 lines from 12 different classes of exponentially growing human tumor cells (sarcomas, lung cancers, colo-rectal cancers, medulloblastomas, melanoma, breast cancers, prostate cancers, renal cell cancers, grades III and IV brain tumors, ovarian, and head and neck cancers). This information was used to intercompare survival after single high doses of 20-40 Gy for each tumor line. Radiosensitivities could roughly be divided into two groups. The more radiosensitive group included: sarcoma, small-cell lung cancer, non-small cell lung cancer, colorectal cancer, medulloblastoma and melanoma. The more radioresistant group included breast, prostate, renal cell, primary brain tumors, ovarian tumors, and head and neck cancers. Using a model of a 3 cm diameter brain lesion containing about 1.4 x 10(9) oxic cells, the single doses calculated to reduce survival to 1 cell were: sarcoma and small cell lung cancers-22-23 Gy; melanoma-25 Gy; non-small cell lung and colorectal cancer-26 Gy; medullo-blastoma-28 Gy; breast, prostate, renal cell, primary brain tumors, ovarian tumors, and head and neck cancers-30-36 Gy. If, however, tumors contained on average 20 percent hypoxic cells, the dose needed for equivalent cell killing increased by about a factor of 2.6-2.8. Also, there was no correlation between the ranking of relative radiosensitivities of the various classes of tumor cells at high doses (as in radiosurgery) to the sensitivity at low doses (as in conventional fractionated radiotherapy). CONCLUSION: available information on the intrinsic radiosensitivity of human tumor cells indicates that meaningful differences exist among different histological classes of neoplasm that are relevant to the single high doses used in radioneurosurgery, and which could constitute a basis for "tailoring" the administered dose to the particular neoplasm. However, if intracerebral lesions contain a large number of hypoxic cells (e.g., 20%), this may constitute a significant problem.

Mast cells and tissue reaction to intraperitoneally implanted polymer capsules.

The inflammatory reaction to implanted biomaterials often compromises the clinical usefulness of implantable devices. Dexamethasone, an anti-inflammatory agent, acts on macrophages to decrease production of inflammatory mediators, and on mast cells to prevent degranulation. Systemic administration of dexamethasone (dms) in rats decreases the tissue reaction to intraperitoneally implanted vinyl chloride-acrylic copolymer capsules. Local release of even smaller amounts of dms from a polymeric substrate placed inside an acrylic copolymer capsule may control the tissue reaction while avoiding the undesirable side effects of systemic treatment. Such a system also allows investigation of the local effect of soluble molecules on tissue-material interactions without altering the surface properties of the implant or adding the effect of a releasing material. In the present study, we investigated the effect of dms released from ethylene vinyl acetate (EVAc) rods placed in acrylic copolymer capsules and implanted in the peritoneal cavity of rats. In vitro the release of dms from EVAc rods was quasilinear for 5 weeks. When implanted intraperitoneally into rats, polymer capsules containing EVAc/dms rods generated a tissue reaction that was significantly thinner and featured fewer fibroblast and collagen layers than that around capsules containing pure EVAc rods at all time points studied. The tissue reaction layer was also thinner than that previously described in rats treated systemically with dms. The trabeculae of implants with dms-loaded EVAc rods contained significantly more intact mast cells than implants with EVAc alone, suggesting that degranulation of mast cells is involved in the tissue reaction to intraperitoneal polymer implants.

Macroencapsulation of dopamine-secreting cells by coextrusion with an organic polymer solution.

A new method of coextruding living cells in the core of a forming hollow fibre is described. PC12 cells, an immortalized cell line which secretes large amounts of dopamine, and dissociated bovine adrenal chromaffin cells, a non-dividing cell type which also secretes dopamine, were coextruded by a dry-jet wet spinning technique through a double-lumen spinneret from a 15% weight by volume solution of poly(acrylonitrile vinyl chloride) in either dimethylsulphoxide (DMSO), dimethylacetamide (DMAC) or dimethylformamide (DMF). Closure of the fibre was achieved by mounting polytetrafluoroethylene tubes on a rotating coaxial wheel system which squeezed the forming hollow fibre at regular intervals. Spontaneous and potassium-stimulated release of catecholamines from the macrocapsules were quantified under static conditions by ion-pair reverse-phase high-performance liquid chromatography equipped with electrochemical detection at 2, 4 and 6 wk. At all time periods, coextruded macrocapsules with either PC12 cells or adrenal chromaffin cells released dopamine under either unstimulated or stimulated conditions. An increase over time in dopamine release was observed from PC12 cell coextruded macrocapsules with observable difference between capsules extruded with DMSO, DMAC or DMF as solvents. Well-preserved PC12 cells and adrenal chromaffin cells were present in coextruded macrocapsules with no observable difference between capsules extruded with DMSO, DMAC or DMF as inocuity of macroencapsulation by coextrusion from an organic polymer solution. Owing to the particular fluid dynamics of this technique, minimal potentially toxic cell-solvent contact occurs allowing the use of a wider range of water-insoluble polymeric systems.(ABSTRACT TRUNCATED AT 250 WORDS)

NGF released from a polymer matrix prevents loss of ChAT expression in basal forebrain neurons following a fimbria-fornix lesion.

Following a unilateral fimbria-fornix lesion, the delivery of nerve growth factor (NGF) to the ipsilateral lateral ventricle of the rat can prevent the lesion-induced loss of choline acetyltransferase (ChAT) expression in the ipsilateral medial septum and vertical diagonal band region. In the present study, the ability of polymer rods to deliver NGF and to prevent a decrease in basal forebrain ChAT expression following a fimbria-fornix lesion was assessed. NGF was loaded into an ethylene vinyl acetate copolymer (EVAc) rod, fabricated by a melt-extrusion process. NGF release was established by the ability of the rods to induce neurite extension from PC12 cells and chick E12 dorsal root ganglia. Unilateral aspirative lesions of the fimbria-fornix were performed in adult rats, followed by implantation of a polymer rod into the ipsilateral lateral ventricle. Five animals received EVAc rods containing only the carrier molecule bovine serum albumin (BSA), and six received EVAc rods containing both BSA and NGF. After 2 weeks, ChAT-positive cells were counted in the medial septum and vertical diagonal band regions. Rats with NGF-releasing rods displayed ChAT(+) cell counts ipsilateral to the lesion equal to 88% of those on the contralateral side. In contrast, ChAT(+) cell numbers were 42% in animals with rods releasing BSA only (P less than 0.001). No undue reaction to implanted rods was noted. Following a fimbria-fornix lesion, NGF released from polymer matrices effectively prevents a lesion-induced reduction in ChAT expression in basal forebrain neurons.

An encapsulated dopamine-releasing polymer alleviates experimental parkinsonism in rats.

The effect of sustained intrastriatal release of dopamine (DA) from polymer matrices on apomorphine-induced turning behavior in a 6-hydroxydopamine (6-OHDA) unilaterally lesioned rat model was analyzed. A biocompatible semipermeable tube was placed in a denervated striatum as a receptacle for DA-releasing polymer rods. In vitro kinetics showed sustained release of DA from a polymeric rod for 15 days. Implantation of a DA-releasing rod within the striatal receptacle significantly decreased apomorphine-induced rotational behaviour in lesioned animals. Upon removal of the DA-releasing system from the receptacle, rotational behaviour increased within 2 weeks and approached preimplant control values 4 weeks later. Acute microdialysis revealed that DA appeared in the extracellular space within 20 min after the implantation of a DA-releasing rod into a denervated striatum. Significant DA amounts were still measurable 7 days postimplantation, indicating sustained DA release from the polymer rod. Dopamine released from a polymer matrix through a semipermeable receptacle alleviates experimental parkinsonism in rats, suggesting that controlled intrastriatal release of DA from a polymer matrix may provide an alternative method for the treatment of Parkinson's disease.

Acid phosphatases bind to the main high density lipoprotein apolipoprotein A-I.

The serum protein binding secretory prostatic acid phosphatase (PAP) and lysosomal placental acid phosphatase (LAP) was purified using affinity chromatography on gels containing immobilized acid phosphatases. The protein, which could be eluted from these enzyme affinity gels only with 0.05 mol/l HCl (pH 2.0), was shown to be apolipoprotein A-I (apo A-I), the main structural protein of high density lipoprotein (HDL).