Tissue culture of adult human neurons

Canadian Pioneers of Amyotrophic Lateral Sclerosis: A Brief History

This is an historical account of Canadian pioneers working in amyotrophic lateral sclerosis (ALS) in the 1970s and 1980s. Key contributions included the development of specialized clinics, the ALS Society of Canada, human motor unit estimates in vivo, use of transcranial magnetic stimulation (TMS), the dementias of ALS, the importance of neurofilaments and axonal flow, neuroinflammation and immunity related to ALS, use of tissue culture to study pathogenesis, and the story of ALS in Guam. Their work set the stage for future generations of ALS physicians and scientists to bring about meaningful therapies and hopefully a cure for ALS.

Isolation and culture of functional adult human neurons from neurosurgical brain specimens

The ability to characterize and study primary neurons isolated directly from the adult human brain would greatly advance neuroscience research. However, significant challenges such as accessibility of human brain tissue and the lack of a robust neuronal cell culture protocol have hampered its progress. Here, we describe a simple and reproducible method for the isolation and culture of functional adult human neurons from neurosurgical brain specimens. In vitro, adult human neurons form a dense network and express a plethora of mature neuronal and synaptic markers. Most importantly, for the first time, we demonstrate the re-establishment of mature neurophysiological properties in vitro, such as repetitive fast-spiking action potentials, and spontaneous and evoked synaptic activity. Together, our dissociated and slice culture systems enable studies of adult human neurophysiology and gene expression under normal and pathological conditions and provide a high-throughput platform for drug testing on brain cells directly isolated from the adult human brain.

Human in vitro systems for examining synaptic function and plasticity in the brain

The human brain shows remarkable complexity in its cellular makeup and function, which are distinct from nonhuman species, signifying the need for human-based research platforms for the study of human cellular neurophysiology and neuropathology. However, the use of adult human brain tissue for research purposes is hampered by technical, methodological, and accessibility challenges. One of the major problems is the limited number of in vitro systems that, in contrast, are readily available from rodent brain tissue. With recent advances in the optimization of protocols for adult human brain preparations, there is a significant opportunity for neuroscientists to validate their findings in human-based systems. This review addresses the methodological aspects, advantages, and disadvantages of human neuron in vitro systems, focusing on the unique properties of human neurons and synapses in neocortical microcircuits. These in vitro models provide the incomparable advantage of being a direct representation of the neurons that have formed part of the human brain until the point of recording, which cannot be replicated by animal models nor human stem-cell systems. Important distinct cellular mechanisms are observed in human neurons that may underlie the higher order cognitive abilities of the human brain. The use of human brain tissue in neuroscience research also raises important ethical, diversity, and control tissue limitations that need to be considered. Undoubtedly however, these human neuron systems provide critical information to increase the potential of translation of treatments from the laboratory to the clinic in a way animal models are failing to provide.

Review : Neuronal Precursor Cells and Neurogenesis in the Adult Forebrain

Neuronal precursor cells persist in the forebrain of a wide variety of adult vertebrates and have been found in cultures derived from fish, birds, rodents, and humans. These cells reside within the periventricular epen dymal/subependymal zone (SZ), rather than the brain parenchyma. In vivo, these precursors may generate neurons that are recruited to restricted regions, such as the avian neostriatum and mammalian olfactory bulb. In vitro, however, neuronal precursor cells have been found to be distributed more widely than suggested by the limited distribution of adult neurogenesis in vivo; in the adult rat brain, new neurons arise from SZ explants derived from most of the surface of the lateral ventricular system. In primates, although the postnatal forebrain SZ largely ceases neurogenesis in vivo, it too retains the capacity for neuronal production in vitro, as dem onstrated in explants of adult human temporal lobe SZ. In mammals, the division of these precursor cells may be regulated by both epidermal and fibroblast growth factors, whereas the survival of their neuronal progeny is regulated in part by members of the neurotrophin family, specifically BDNF and NT-4. Together, these findings suggest the persistence into adulthood of a relatively widespread pool of SZ progenitor cells, which remains neurogenic in selected regions, but which more generally becomes vestigial, perhaps as a result of the loss of permissive signals for daughter cell migration or survival in the local environment. The Neuroscientist 1:338-350, 1995

Lipofuscin in saliva and plasma and its association with age in healthy adults

BACKGROUND AND AIM

To compare blood and salivary levels of lipofuscin in healthy adults and to analyze the relationship between the lipofuscin level and the healthy adults' age.

METHODS

One hundred and twenty-two healthy volunteers were recruited and divided into three groups according to their age: young (n = 42, 20-44 years old), middle-aged (n = 51, 45-59 years old), and elderly (n = 29, 60-74 years old). One ml saliva and 5 ml whole blood were collected from each person. An ELISA kit was used to measure both the plasma and salivary lipofuscin levels. The differences between the groups were compared with independent-sample t test, and the relationship between the salivary lipofuscin level and the age was assessed with linear regression analysis.

RESULTS

The mean ± SD of the lipofuscin level in the saliva and plasma of 122 subjects was 68.93 ± 1.32 and 78.05 ± 1.75 μmol/l, respectively. No gender-dependent differences were observed in either the salivary or the plasma lipofuscin level (saliva: p = 0.443, plasma: p = 0.459). The salivary and plasma lipofuscin levels of the elderly subjects were significantly higher than those of the young (saliva: 80.72 ± 13.53 mmol/l versus 59.12 ± 1.92 mmol/l, p = 0.0003; plasma: 93.31 ± 3.14 mmol/l versus 67.43 ± 2.54 mmol/l, p = 0.0002) and middle-aged (saliva: 80.72 ± 13.53 mmol/l versus 70.31 ± 11.17 mmol/l, p = 0.0004; plasma: 93.31 ± 3.14 mmol/l versus 78.12 ± 2.40 mmol/l, p = 0.0002) subjects. Similarly, the salivary and plasma lipofuscin levels of the middle-aged subjects were significantly higher than those of the young subjects (saliva: 70.31 ± 11.17 mmol/l versus 59.12 ± 1.92 mmol/l, p < 0.0001; plasma: 78.12 ± 2.40 mmol/l versus 67.43 ± 2.54 mmol/l, p = 0.0019). The lipofuscin levels in the saliva and plasma were significantly positively correlated with the subject age (r = 0.551, p = 0.0001; r = 0.528, p < 0.0001). Furthermore, the salivary lipofuscin level and plasma lipofuscin level also were found to have a positive correlation (r = 0.621, p < 0.0001).

CONCLUSION

No gender-dependent differences were observed in either the salivary or plasma lipofuscin levels. The salivary and plasma lipofuscin levels were positively correlated, and the age is positively correlated with lipofuscin content in saliva.

Harvested human neurons engineered as live nervous tissue constructs: implications for transplantation. Laboratory investigation

OBJECT

Although neuron transplantation to repair the nervous system has shown promise in animal models, there are few practical sources of viable neurons for clinical application and insufficient approaches to bridge extensive nerve damage in patients. Therefore, the authors sought a clinically relevant source of neurons that could be engineered into transplantable nervous tissue constructs. The authors chose to evaluate human dorsal root ganglion (DRG) neurons due to their robustness in culture.

METHODS

Cervical DRGs were harvested from 16 live patients following elective ganglionectomies, and thoracic DRGs were harvested from 4 organ donor patients. Following harvest, the DRGs were digested in a dispase-collagenase treatment to dissociate neurons for culture. In addition, dissociated human DRG neurons were placed in a specially designed axon expansion chamber that induces continuous mechanical tension on axon fascicles spanning 2 populations of neurons originally plated approximately 100 microm apart.

RESULTS

The adult human DRG neurons, positively identified by neuronal markers, survived at least 3 months in culture while maintaining the ability to generate action potentials. Stretch-growth of axon fascicles in the expansion chamber occurred at the rate of 1 mm/day to a length of 1 cm, creating the first engineered living human nervous tissue constructs.

CONCLUSIONS

These data demonstrate the promise of adult human DRG neurons as an alternative transplant material due to their availability, viability, and capacity to be engineered. Also, these data show the feasibility of harvesting DRGs from living patients as a source of neurons for autologous transplant as well as from organ donors to serve as an allograft source of neurons.

Human central nervous system tissue culture: a historical review and examination of recent advances

Tissue culture has been and continues to be widely used in medical research. Since the beginning of central nervous system (CNS) tissue culture nearly 100 years ago, the scientific community has contributed innumerable protocols and materials leading to the current wide variety of culture systems. While nonhuman cultures have traditionally been more widely used, interest in human CNS tissue culture techniques has accelerated since the middle of the last century. This has been fueled largely by the desire to model human physiology and disease in vitro with human cells. We review the history of human CNS tissue culture summarizing advances that have led to the current breadth of options available. The review addresses tissue sources, culture initiation, formats, culture ware, media, supplements and substrates, and maintenance. All of these variables have been influential in the development of culturing options and the optimization of culture survival and propagation.

Cells in human postmortem brain tissue slices remain alive for several weeks in culture

Animal models for human neurological and psychiatric diseases only partially mimic the underlying pathogenic processes. Therefore, we investigated the potential use of cultured postmortem brain tissue from adult neurological patients and controls. The present study shows that human brain tissue slices obtained by autopsy within 8 h after death can be maintained in vitro for extended periods (up to 78 days) and can be manipulated experimentally. We report for the first time that 1) neurons and glia in such cultures could be induced to express the reporter gene LacZ after transduction with adeno-associated viral vectors and 2) cytochrome oxidase activity could be enhanced by the addition of pyruvate to the medium. These slice cultures offer new opportunities to study the cellular and molecular mechanisms of neurological and psychiatric diseases and new therapeutic strategies.

Effects of a traditional Chinese medicine, Qing Nao Yi Zhi Fang, on glutamate excitotoxicity in rat fetal cerebral neuronal cells in primary culture

Qing Nao Yi Zhi Fang (QNYZ), a traditional Chinese medicine, has been developed as a drug to be used for the prevention and treatment of vascular dementia. However, the mechanisms by which this drug affects vascular dementia remain unknown. We examined the effects of QNYZ serum on glutamate excitotoxicity in rat fetal cerebral neuronal cells in primary culture. Exposure of neuronal cells to glutamate leads to a decrease in the activities of cholinesterase, superoxide dismutase, and streptoavidin peroxidase, and an increase in lactate dehydrogenase release. These enzyme activities were restored to the levels in untreated cells by the addition of QNYZ serum. QNYZ serum suppressed the increased nitric oxide production induced by glutamate and prevented glutamate-mediated apoptosis. QNYZ serum also improved mitochondrial energy metabolism after glutamate exposure. These findings suggest that QNYZ has protective effects against glutamate-mediated excitotoxicity in neuronal cells during ischemic brain injury.

Isolation and long-term survival of adult human sensory neurons in vitro

OBJECTIVE

To determine whether adult human dorsal root ganglion neurons can be isolated and maintained in long-term tissue culture, where they would extend processes.

METHODS

Dorsal root ganglia were removed from adult human organ donors within 2 hours of clamping the aorta. They were then treated with enzymes for one hour, triturated to dissociate the neurons and their satellite cells, and the individual neurons were then plated in tissue culture dishes in medium containing serum.

RESULTS

Isolated adult human dorsal root ganglion neurons survive in vitro for more than 2 1/2 months, in the absence of exogenously supplied neurotrophins. where they remain electrically excitable and extend processes,

CONCLUSIONS

Isolated adult human dorsal root ganglion neurons survive in culture for more than 2 1/2 months, extend processes, and remain electrically excitable, without exogenous neurotrophins. These results suggest that, adult human sensory neurons do not require exogenous neurotrophins for survival and process outgrowth, or that sufficient factors were provided by the small number of satellite cells in the cultures. In addition, the neurons survive well in spite of an initial period of up to 14 hours of hypoxia, between the time the aorta was clamped and when the plated neurons were placed in an incubator with the appropriate O2/CO2 environment.

Plasticity of developing and adult dorsal root ganglion neurons as revealed in vitro

We review recent data on the plasticity of dorsal root ganglion (DRG) neurons as revealed during cultivation in vitro. Some experiments on cultured developing DRG neurons and on adult DRG neurons in vivo are also mentioned. Cultured developing and adult DRG neurons can be switched from an apolar to a multipolar phenotype by fetal calf serum or fibronectin. The effect is concentration dependent and occurs through an early modification of cell-substratum interaction. Adult DRG neurons synthesize and release within hours after injury TGF beta-1, which is a mitogen and a differentiation factor for Schwann cells. Finally, adult DRG neurons express in vitro neurotransmitters that are not expressed in vivo. This neurotransmitter plasticity can be modulated in vitro by some growth factors and in vivo by distal or proximal axotomy.

Newly generated neurons of the adult songbird brain become functionally active in long-term culture

The vocal control nucleus, HVc, of the songbird forebrain undergoes neurogenesis in adulthood, as ventricular zone precursor cells divide and their daughter cells migrate into the subjacent forebrain, where they differentiate into neurons. We have previously demonstrated that the migration and development of these new neurons can proceed in vitro, in HVc ventricular zone explant cultures derived from the adult canary HVc. By a combination of electron microscopy and electrophysiology, we now report that these newly produced neurons become functionally mature and synaptically competent in culture. These cells developed synaptic contacts which became morphologically evident during the second week in culture, and which preceded the development of both stimulus-evoked and spontaneous action potentials during the second and third weeks in vitro. Thus, the newly generated neurons of the adult avian forebrain can form structurally complex, electrically interactive networks in long-term culture.

TCP enhances the survival of human fetal spinal cord cells in culture

Dissociated cell cultures were prepared from human spinal cords of 7-10-week-old fetuses. After 10 weeks progressive neuronal necrosis was observed in controls whereas N/1-(2-thienyl)cyclohexyl/piperidine (TCP) enhanced the survival time of the cells. After 21 weeks the number of gamma-aminobutyric acid (GABA)ergic and neuron specific enolase (NSE)-stained neurons was higher in the TCP-treated cultures than in controls. TCP appears to be a promising drug for long term survival of neurons.

Light and electron microscopic features of peripheral ganglion cells cultured from young and aged Wistar rats

Neurons of the dorsal root ganglion (DRG) and sympathetic superior cervical ganglion (SCG) were cultured as explants from young adult (3 months old) and aged (28 months old) Wistar rats. Both aged DRG and SCG neurons showed delayed neurite outgrowth compared to young adult neurons. Young and some aged cultured neurons had an ultrastructure similar to that found in normal uncultured cells, but most of the aged cultured neurons displayed a heavy accumulation of homogenous lipid-like inclusions in addition to classic age pigments. Occasionally, large neurofilament aggregates were seen in aged DRG neurons. They were sometimes localized perinuclearly, resembling neurofibrillary tangles. The results show that even very old peripheral neurons survive in culture. As aged cultured neurons show degenerative changes not observed in young adult neurons, it is suggested that cultured peripheral neurons of different ages could provide useful means for neuronal aging studies.

Purification and culture of adult rat dorsal root ganglia neurons

To study the trophic requirements of adult rat dorsal root ganglia neurons (DRG) in vitro, we developed a purification procedure that yields highly enriched neuronal cultures. Forty to fifty ganglia are dissected from the spinal column of an adult rat. After enzymatic and mechanical dissociation of the ganglia, myelin debris are eliminated by centrifugation on a Percoll gradient. The resulting cell suspension is layered onto a nylon mesh with a pore size of 10 microns. Most of the neurons, the diameter of which ranged from 17 microns to greater than 100 microns, are retained on the upper surface of the sieve; most of the non-neuronal cells with a caliber of less than 10 microns after trypsinization go through it. Recovery of neurons is achieved by reversing the mesh onto a Petri dish containing culture medium. Neurons to non-neurons ratio is 1 to 10 in the initial cell suspension and 1 to 1 after separation. When these purified neurons are seeded at a density of 3,000 neurons/cm2 in 6 mm polyornithine-laminin (PORN-LAM) coated wells, neuronal survival (assessed by the ability to extend neurites), measured after 48 hr of culture, is very low (from 0 to 16%). Addition of nerve growth factor (NGF) does not improve neuronal survival. However, when neurons are cultured in the presence of medium conditioned (CM) by astrocytes or Schwann cells, 60-80% of the seeded, dye-excluding neurons survive. So, purified adult DRG neurons require for their short-term survival and regeneration in culture, a trophic support that is present in conditioned medium from PNS or CNS glia.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of dissociated monolayer cultures of human spinal cord

Embryonic human spinal cord cells have been grown in dissociated monolayer cultures for 1 to 7 weeks. Using cell type specific markers, it was possible to show that the cultures contain neurons, astrocytes and fibroblasts. Electrical membrane properties were studied with patch electrodes using the whole cell recording technique. Neurons had short duration action potentials that could be blocked by tetrodotoxin. The membrane currents in these neurons were studied in voltage clamp experiments. Three types of voltage-dependent currents were observed: a sodium current; a potassium current made up of two components, IA and IK; and a calcium current. Both cholinergic and GABAergic neurons are present in the cultures. There is more choline acetyltransferase activity in cultures prepared from the anterior as compared to the posterior part of the spinal cord, suggesting that the cultures contain motoneurons. This tissue culture preparation was developed for the study of amyotrophic lateral sclerosis; we have been unable to detect the presence of any toxic agent from the serum of these patients on the cultured cells. Experiments are in progress to purify the motoneurons using Percoll gradients.

Computer-assisted analysis of the developing Purkinje neuron. I. Effects of the age of the animal at the moment of explantation on the subsequent dendritic development in organotypic cultures

Purkinje cell dendritic arborization were studied in intracellularly horseradish peroxidase-stained mature neurons grown during 30-40 days in organotypic cerebellar cultures from kittens of various ages. The effects of the age of the animal at the moment of explantation upon the subsequent dendritic and axonal development were studied in kitten cerebella of 1, 12 and 21 postnatal days old. These effects were investigated by computer-assisted methods. Qualitative data were found to be different in these 3 in vitro models explanted at 3 different ages except for the spine development which remained the same. Quantitative data, obtained from 15 measurable parameters, showed that the degree of dendritic development was higher for the Purkinje cells explanted at the latest postnatal age: the older the animal, the larger the dendritic tree in culture. A discrimination analysis permitted a recognition of the 3 differently aged populations (94% well classified cells) based on 3 selected variables, number of primary dendritic trunks, number of rows and dendritic field areas. These results lend further support to the major role played in the final dendritic arrangement by extrinsic (discriminant factors, their pre-existence in vivo being responsible for the subsequent degree of the in vitro development of the Purkinje cell dendritic arbor.

Age related heterogeneity of lipopigments in human sympathetic ganglia

The histochemical, autofluorescence and morphological characteristics of lipopigments accumulating with age in the human sympathetic neurons were studied. The spectral characteristics of the lipopigment autofluorescence change with age suggesting the accumulation of additional components in the residual bodies. This component is electron microscopically highly osmiophilic and stains also with silver staining. These changes may indicate the gradual melanization of the lipopigments due to auto-oxidation of catecholamines. The accumulation of the melanized form of lipopigment may be a sign of more advanced cellular trauma.

Specificity of a neuronotrophic factor from rabbit corneal epithelial cultures

Previous studies have demonstrated that of the three major cell types of rabbit cornea, only epithelial cells released a neuronotrophic factor that is active in both promoting survival and inducing neurite outgrowth of dissociated trigeminal neurons. In this study, the specificity of neuronotrophic factor production by selected epithelial cell types and the responsiveness of neurons from several different tissues to this trophic factor were determined. Cell cultures of various epithelia and dissociated neurons from several ganglia of neonatal and adult rabbits were utilized. In comparison with adult corneal epithelium, adult bulbar conjunctiva released a similar amount of trophic factor. Neonatal corneal epithelium released five times more, but adult retinal pigment epithelium and neonatal skin epithelium yielded less than a third and one-sixth respectively, and three cell lines (adult skin, kidney and neonatal lens epithelia) released only negligible amounts. Compared with its effect on neonatal trigeminal neurons, the trophic factor from adult corneal epithelium was similarly active on neonatal dorsal root neurons, but only half as effective on adult trigeminal neurons and less than one-tenth as effective on neonatal superior cervical neurons. The effect of nerve growth factor (from mouse submaxillary gland) on these neurons was tested for comparison. The results indicated that of the tissues studied, neuronotrophic factor was released in abundance only from corneal and conjunctival epithelia, and was active predominantly on trigeminal and dorsal root neurons (sensory neurons). This is consistent with the concept that the developmentally regulated release of trophic factor by target cells may be an underlying mechanism for neurogenesis and nerve regeneration.

NGF-dependent and -independent growth of neurites from sympathetic ganglion cells of the aged human in a serum-free culture

Small pieces of tissue isolated from abdominal sympathetic ganglia in aged male patients were cultured in a chemically defined, serum-free medium. The growth of neurites from pieces of ganglia in cultures with and without 50 ng/ml mouse 2.5S nerve growth factor (NGF) was compared. The NGF stimulated significantly greater regeneration of neurites, causing the growth of long fibers from the ganglion pieces. Many short neurites grew, even in the absence of the NGF, but these were generally short, except for long neurites generated in several nerve cells. A method was devised for the evaluation of NGF-dependent growth of neurites in the culture. The rate of the NGF-dependent growth of neurites, which was calculated by the difference in the total lengths of the NGF-dependent neurites between 2- and 4-day-old cultures, was approximately 160 micron/day. The results indicate that although the growth of neurites from some sympathetic nerve cells of the aged human become independent of the NGF, most of the nerve cells remain dependent on the NGF, even in the stage of senescence.

Long-term cultures of human adult Schwann cells isolated from autopsy materials

Enriched populations of adult human Schwann cells were obtained from trigeminal ganglia and roots of autopsy material. The cells, isolated by enzymatic procedure, were seeded on rat tail collagen-coated coverslips. Subcultures were established several weeks later, and secondary cells were grown on polylysine-coated coverslips and maintained in vitro for as long as 5 months. The Schwann cells in culture displayed the same light- and electron-microscopic features and arrangement as those cells observed in vivo. The addition of bovine pituitary glial growth factor in the medium induced a 3-5-fold increase in Schwann cell division.

Long-term culture of neurones from human cerebral cortex in serum-free medium

A method for cultivating neurones from the fetal human central nervous system in the absence of glial cells is described. Brain cells from 15-18-week-old human fetuses are plated on polylysine-coated surfaces and grown in a serum-free hormonally-defined medium. About 98% of the cells were identified as neurones using tetanus toxin as a marker. The cultures survive for up to 7 weeks and develop an extremely complex network of neurites.

Fine-structural and degenerative features in adult and aged human sympathetic ganglion cells

Sympathetic ganglia, either cervical and upper thoracic or lumbar, were removed from adult and aged patients suffering from circulatory deficiencies in their upper or lower extremities, respectively. The ganglion cells had several features that can be associated with age. Lipofuscin was ample in all ganglion cells and was usually polarly concentrated. Its amount tended to increase with age and it was present also in the glial cells. Lipofuscin autofluorescence often prevented the visualization of the formaldehyde induced fluorescence for catecholamines. At the electron microscopic level, pigment bodies were seen to be composed of three different kinds of osmiophilic properties: (1) gray component that had (2) dark patches dispersed into it and (3) pale, oval, incorporated droplets. In principal ganglion cells, the first two formed the major part, the pale one taking over in the small granule-containing cells. Various inclusion bodies included a cylinder-shaped type that had a varying pattern of rod-like structures inside it. Myelin figures (laminar bodies) were sometimes found to fill neurite profiles, occasionally with random mitochondrial accumulations. These bore a distant resemblance to the primitive type of neuritic (senile) plaques, although none of the patients was diagnosed to have, for example, Alzheimer's disease or senile dementia of the Alzheimer type. Nevertheless, it appears to us that it might be possible to find coexistent neuropathological changes in peripheral sympathetic ganglia in diseases affecting primarily the central nervous system.

Sympathetic ganglion neurons from aged humans grown in monolayer culture

Sympathetic ganglia were dissected from aged patients during surgical operation done for a therapeutic purpose in the University Hospital. Nerve cells were isolated from the ganglia by trituration after incubation with collagenase, and were grown on collagen-coated plastic dishes with a growth medium. These nerve cells regenerated their axons and survived in the tissue culture for more than 3 weeks. The nerve cells tended to reduce the size in an early stage of the in vitro growth.

Non-neuronal cell cultures from dorsal root ganglia of the adult cat: production of Schwann-like cell lines

There are several methods available for the production of Schwann cell cultures from fetal and neonatal peripheral nervous tissue. We have investigated methods for producing Schwann cell-rich cultures from adult tissue. Dorsal root ganglia from normal adult cats were used to initiate explant cultures or subjected to primary dissociation. The resulting cultures were compared in terms of growth, the proportions of fibroblastic and Schwann-like cells in primary cultures and the effects of subculture on the relative frequency of these cell types. We found that excision and transfer of explanted ganglion pieces after 14 days in culture produced a secondary outgrowth rich in small, bipolar, spindle-shaped Schwann-like cells. Subculture of this outgrowth produced secondary cultures of predominantly Schwann-like cells with typical spindle-shaped morphology. The use of antimitotic agents in the media to inhibit fibroblast growth was not observed to be necessary or beneficial with this adult tissue. Primary dissociation of ganglia with enzymes (trypsin or collagenase) and mechanical agitation was even more effective in producing secondary cultures and cell lines that were, by morphological criteria, predominantly or exclusively Schwann-like cells. One of these Schwann-like cell lines, designated GSA, has been carried over 24 subcultures while retaining characteristic Schwann cell morphology. Cells of this line have been examined by scanning and transmission electron microscopy. Karyotype analysis indicates a chromosome complement consistent with the species of origin, a normal cat.

Electrophysiological properties of tissue-cultured nerve cells from senescent mouse

Nerve cells were isolated from dorsal root ganglia of senescent mouse (C57 black, male) by collagenase and were grown on collagen-coated plastic dishes. The nerve cells extended their neurites and survived for more than 3 weeks in vitro. Intracellular recording with a glass microelectrode revealed that, although their resting membrane potential was small, the tissue-cultured nerve cells recovered membrane excitability after continuous hyperpolarization by DC current passage. Both Na and Ca spikes were elicited in thus hyperpolarized nerve cells. Some nerve cells generated tetrodotoxin-resistant Na spikes.

Astrocytes and oligodendrocytes in dissociated cell culture of adult rat optic nerve

We have prepared dissociated cell cultures from adult rat optic nerve. After 48 h in culture cells of both fibroblastic and process-bearing morphology could be recognised. Using indirect immunofluroescence and cell-type specific markers it was possible to unambiguously identify astrocytes and oligodendrocytes in culture. Approximately 0.1% of cells were galactocerebroside+ oligodendrocytes, 20% were GFAP+ astrocytes and 30% were fibronectin+, Thy-1+, GFAP- fibroblastoid cells. Fifty percent of the GFAP+ astrocytes expressed the Thy-1 antigen but none of them expressed fibronectin. All of the oligodendrocytes expressed intracellular myelin basic protein. Thus, glial cells isolated from adult tissues were similar in their antigenic properties to such cells isolated from neonatal tissues.

Neurofibrillary degeneration in cultured adult mouse neurons induced by maytansine

The effects of maytansine, an antimitotic compound isolated from an African plant, were studied by light and electron microscopy in dissociated cell cultures of adult mouse dorsal root ganglia. Maytansine at 10-100 ng/ml concentration caused reversible, concentration-dependent, inhibition of microtubule assembly and induction of a large amount of 10 nm filaments in the cytoplasm of cultured neurons and Schwann cells.