Growth factor-induced neurite growth in primary neuronal cultures of dogs with neuronal ceroid lipofuscinosis

Use of model organisms for the study of neuronal ceroid lipofuscinosis

Neuronal ceroid lipofuscinoses are a group of fatal progressive neurodegenerative diseases predominantly affecting children. Identification of mutations that cause neuronal ceroid lipofuscinosis, and subsequent functional and pathological studies of the affected genes, underpins efforts to investigate disease mechanisms and identify and test potential therapeutic strategies. These functional studies and pre-clinical trials necessitate the use of model organisms in addition to cell and tissue culture models as they enable the study of protein function within a complex organ such as the brain and the testing of therapies on a whole organism. To this end, a large number of disease models and genetic tools have been identified or created in a variety of model organisms. In this review, we will discuss the ethical issues associated with experiments using model organisms, the factors underlying the choice of model organism, the disease models and genetic tools available, and the contributions of those disease models and tools to neuronal ceroid lipofuscinosis research. This article is part of a Special Issue entitled: The Neuronal Ceroid Lipofuscinoses or Batten Disease.

Neuropeptide changes and neuroactive amino acids in CSF from humans and sheep with neuronal ceroid lipofuscinoses (NCLs, Batten disease)

Anomalies in neuropeptides and neuroactive amino acids have been postulated to play a role in neurodegeneration in a variety of diseases including the inherited neuronal ceroid lipofuscinoses (NCLs, Batten disease). These are often indicated by concentration changes in cerebrospinal fluid (CSF). Here we compare CSF neuropeptide concentrations in patients with the classical juvenile CLN3 form of NCL and the classical late infantile CLN2 form with neuropeptide and neuroactive amino acid concentrations in CSF from sheep with the late infantile variant CLN6 form. A marked disease related increase in CSF concentrations of neuron specific enolase and tau protein was noted in the juvenile CLN3 patients but this was not observed in an advanced CLN2 patient nor CLN6 affected sheep. No changes were noted in S-100b, GFAP or MBP in patients or of S-100b, GFAP or IGF-1 in affected sheep. There were no disease related changes in CSF concentrations of the neuroactive amino acids, aspartate, glutamate, serine, glutamine, glycine, taurine and GABA in these sheep. The changes observed in the CLN3 patients may be progressive markers of neurodegeneration, or of underlying metabolic changes perhaps associated with CLN3 specific changes in neuroactive amino acids, as have been postulated. The lack of changes in the CLN2 and CLN6 subjects indicate that these changes are not shared by the CLN2 or CLN6 forms and changes in CSF concentrations of these compounds are unreliable as biomarkers of neurodegeneration in the NCLs in general.

Outlook for future treatment

Currently, no treatment is available for neuronal ceroid lipofuscinoses. The progress of human genome project will stimulate molecular cloning of unidentified genes underlying the NCLs, which will lead eventually clinical management and therapies for NCL. Characterizing the native substrate(s) for the palmitoyl-protein thioesterase-1 (PPT1) and tripeptidyl peptidase 1 (TPP1), understanding the protein functions encoded by CLN genes, and uncovering the pathological metabolic mechanism for the NCLs are the bases of designing rational treatments for the NCLs. Testing potential therapeutic agents, replacing deficient enzymes, and developing gene therapy will be the major tasks for NCL researchers.

Canine models for human genetic neurodegenerative diseases

1. Canine models of human neurodegenerative disorders are uncommon. However, the similarity between canines and humans in body sizes and physiology provides an exceptional opportunity to use these models to study human diseases. 2. The authors will present a review on the neurological deficits that have been observed in canine models of genetic neurodegenerative diseases, and summarize the current gene therapy treatments being developed for some of these conditions.

In vitro culture of neurons from sheep with Batten disease

Specific storage of mitochondrial ATP synthase subunit c occurs in most forms of Batten disease, including the ovine form, but its relationship to the characteristic neurodegeneration is not clear. Storage occurs in most cell types but only neurons are functionally affected. Neurons were cultured from control and affected sheep. Ewes were superovulated and inseminated, and embryos were collected, frozen, stored, and later transplanted into surrogate dams for gestation at times to suit experimental demands. The optimal fetal age for cultures was investigated, from 50 to 125 days. There were no differences between control and affected embryos in this period of rapid growth. At 50 days brains consist of smooth-surfaced hemispheres and cerebellum with no obvious demarcation between gray and white matter. At 90 days they are like miniature adult brains. From 200 to 600 million viable cells were recovered from each fetus, regardless of age. DMEM/F12 with B27 was the most practical medium tested. Cell viability was not as good in medium containing serum. Treatment of surfaces with polylysine aided neuron adhesion. No developmental or viability differences were observed between normal and affected neuron cultures. At plating out cells were rounded. A day later single process outgrowths began. After 4 days these were over 200 microm and by Day 6 had created a network. Most neurons were bipolar. Neurons from 50 to 90-day old fetuses persisted in culture for over 100 days.

Apparent loss and hypertrophy of interneurons in a mouse model of neuronal ceroid lipofuscinosis: evidence for partial response to insulin-like growth factor-1 treatment

The neuronal ceroid lipofuscinoses (NCL) are progressive neurodegenerative disorders with onset from infancy to adulthood that are manifested by blindness, seizures, and dementia. In NCL, lysosomes accumulate autofluorescent proteolipid in the brain and other tissues. The mnd/mnd mutant mouse was first characterized as exhibiting adult-onset upper and lower motor neuron degeneration, but closer examination revealed early, widespread pathology similar to that seen in NCL. We used the autofluorescent properties of accumulated storage material to map which CNS neuronal populations in the mnd/mnd mouse show NCL-like pathological changes. Pronounced, early accumulation of autofluorescent lipopigment was found in subpopulations of GABAergic neurons, including interneurons in the cortex and hippocampus. Staining for phenotypic markers normally present in these neurons revealed progressive loss of staining in the cortex and hippocampus of mnd/mnd mice, with pronounced hypertrophy of remaining detectable interneurons. In contrast, even in aged mutant mice, many hippocampal interneurons retained staining for glutamic acid decarboxylase. Treatment with insulin-like growth factor-1 partially restored interneuronal number and reduced hypertrophy in some subregions. These results provide the first evidence for the involvement of interneurons in a mouse model of NCL. Moreover, our findings suggest that at least some populations of these neurons persist in a growth factor-responsive state.

Leukodystrophy and bone marrow transplantation: role of mixed hematopoietic chimerism

Bone Marrow Transplantation (BMT) is currently the most physiologic treatment for some types of leukodystrophies. In enzyme deficiency states, replacement of defective genes with cells carrying "normal" copies of these genes offers a natural form of gene therapy. This review will cover the various disease states which may be treated using bone marrow transplantation as well as the obstacles and advantages offered by this treatment modality. The potential for mixed hematopoietic chimerism, with reference to the advantages and disadvantages of treating various leukodystrophies, is reviewed. Finally, certain approaches which would reduce the morbidity and mortality associated with conventional BMT are discussed. If these obstacles can be overcome, BMT may offer the hope of cure to a number, but certainly not all, leukodystrophies.

Evidence that lysosomal storage of proteolipids is a cell autonomous process in the motor neuron degeneration (mnd) mouse, a model of neuronal ceroid lipofuscinosis

The motor neuron degeneration (mnd) mouse has been documented to accumulate proteolipid and thus is a model of neuronal ceroid lipofuscinosis [Dunn, W.A., Raizada, M.K., Vogt, E.S. and Brown, E.A., Int. J. Dev. Neurosci., 12 (1994) 185-196; Faust, J.R., Rodman, J.S., Daniel, P.F., Dice, J.F. and Bronson, R.T., J. Biol. Chem., 269 (1994) 10150-10155]. While accumulation of proteolipid in the hippocampus of chimeric mice composed of mnd and +/+ cells was found to be proportional to the contribution of mnd in the brain, accumulation within individual cells was the same for cells from chimeric and age-matched mnd mice. Bone marrow transplantation was used to altering the milieu of circulating factors to determine whether this might modify the disease phenotype in mnd mice. Transplantation of bone marrow in neonatal or young mice did not reduce the age-associated accumulation of proteolipid within hippocampal neurons. The results of these experiments indicate that mnd results in a cell autonomous defect.