Follow-up of Acute Respiratory Disorders in Cyclists Competing in the 100th Giro d'Italia.

Acute respiratory disorder is a common sub-clinical condition affecting elite cyclists. Monitoring the perturbations of the immunological cells in the respiratory tract, indicative of a likely proinflammatory state, during an International Cycling Union world tour is a challenging task. The aim of this study was to follow up on the sign and symptoms of upper way respiratory infections with or without asthma, using non-invasive methods, during a 21-day race (100° Giro d'Italia, 2017). Nine male elite cyclists of the Bahrain Merida Team were evaluated before the training season and daily during the race. Clinical history, skin prick and spirometric test, acute respiratory symptoms were measured using validated questionnaires, and values of fraction of exhaled nitric oxide were collected longitudinally. Four of the 9 athletes had allergies with/or consistent abnormal spirometric curves before the race. During the race, 5 athletes had a fraction of exhaled nitric oxide values >20 ppb which correlated with respiratory symptoms collected through questionnaires. These were related to the environmental characteristics of the places travelled through in the race. The athletes with a predisposition to chronic respiratory inflammation in the pre-competitive season were more likely to develop acute respiratory symptoms during the race.

Comparing the different response of PNS and CNS injured neurons to mesenchymal stem cell treatment.

Mesenchymal stem cells (MSCs) are adult bone marrow-derived stem cells actually proposed indifferently for the therapy of neurological diseases of both the Central (CNS) and the Peripheral Nervous System (PNS), as a panacea able to treat so many different diseases by their immunomodulatory ability and supportive action on neuronal survival. However, the identification of the exact mechanism of MSC action in the different diseases, although mandatory to define their real and concrete utility, is still lacking. Moreover, CNS and PNS neurons present many different biological properties, and it is still unclear if they respond in the same manner not only to MSC treatment, but also to injuries. For these reasons, in this study we compared the susceptibility of cortical and sensory neurons both to toxic drug exposure and to MSC action, in order to verify if these two neuronal populations can respond differently. Our results demonstrated that Cisplatin (CDDP), Glutamate, and Paclitaxel-treated sensory neurons were protected by the co-culture with MSCs, in different manners: through direct contact able to block apoptosis for CDDP- and Glutamate-treated neurons, and by the release of trophic factors for Paclitaxel-treated ones. A possible key soluble factor for MSC protection was Glutathione, spontaneously released by these cells. On the contrary, cortical neurons resulted more sensitive than sensory ones to the toxic action of the drugs, and overall MSCs failed to protect them. All these data identified for the first time a different susceptibility of cortical and sensory neurons, and demonstrated a protective action of MSCs only against drugs in peripheral neurotoxicity.

Therapeutic potential of Mesenchymal Stem Cells for the treatment of diabetic peripheral neuropathy.

Type-1 Diabetes is generally treated with exogenous insulin administration. Despite treatment, a very common long term consequence of diabetes is the development of a disabling and painful peripheral neuropathy. The transplantation of pancreatic islets is an advanced alternative therapeutic approach, but its clinical application is still very limited, mainly because of the great number of islets required to complete the procedure and of their short-term survival. An intriguing method to improve the performance of pancreatic islets transplantation is the co-transplantation of Mesenchymal Stem Cells (MSCs), adult stem cells already known to support the survival of different cellular populations. In this proof-of-concept study, we demonstrated using an in vivo model of diabetes, the ability of allogenic MSCs to reduce the number of pancreatic islets necessary to achieve glycemic control in diabetic rats, and overall their positive effect on diabetic neuropathy, with the reduction of all the neuropathic signs showed after disease induction. The cutback of the pancreatic islet number required to control glycemia and the regression of the painful neuropathy make MSC co-transplantation a very promising tool to improve the clinical feasibility of pancreatic islet transplantation for diabetes treatment.

Human endothelial progenitor cells rescue cortical neurons from oxygen-glucose deprivation induced death.

BACKGROUND AND AIM: Cerebral ischemia is characterized by both acute and delayed neuronal injuries. Neuro-protection is a major issue that should be properly addressed from a pharmacological point of view, and cell-based treatment approaches are of interest due to their potential pleiotropic effects. Endothelial progenitor cells have the advantage of being mobilized from the bone marrow into the circulation, but have been less studied than other stem cells, such as mesenchymal stem cells. Therefore, the comparison between human endothelial progenitor cells (hEPC) and human mesenchymal progenitor cells (hMSC) in terms of efficacy in rescuing neurons from cell death after transitory ischemia is the aim of the current study, in the effort to address further directions. MATERIALS AND METHODS: In vitro model of oxygen-glucose deprivation (OGD) on a primary culture of rodent cortical neurons was set up with different durations of exposure: 1, 2 and 3hrs with assessment of neuron survival. The 2hrs OGD was chosen for the subsequent experiments. After 2hrs OGD neurons were either placed in indirect co-culture with hMSC or hEPC or cultured in hMSC or hEPC conditioned medium and cell viability was evaluated by MTT assay. RESULTS: At day 2 after 2hrs OGD exposure, mean neuronal survival was 47.9±24.2%. In contrast, after treatment with hEPC and hMSC indirect co-culture was 74.1±27.3%; and 69.4±18.8%, respectively. In contrast, treatment with conditioned medium did not provide any advantage in terms of survival to OGD neurons CONCLUSION: The study shows the efficacy of hEPC in indirect co-culture to rescue neurons from cell death after OGD, comparable to that of hMSC. hEPC deserve further studies given their potential interest for ischemia.

Body fluid status and physical demand during the Giro d'Italia.

The aim of the study was to investigate changes in hydration status by means of bioelectrical impedance vector analyses (BIVA) and to assess its influence on power output and rating of perceived exertion (RPE) during the Giro d'Italia 2014. Daily bioelectrical impedance analysis were performed on 9 professional road cyclists (age: 28.2 ± 4.7 yr, height: 176.0 ± 5.5 cm, weight: 64.7 ± 3.4 kg) during the race. Additionally, body weight, RPE, and power output were recorded throughout the race. Impedance vectors shortened during the race, whereas body weight remained unchanged at the end of the tour when compared to pre-tour. Vector changes were not related to power output or RPE. The shortening of the BIVA vector indicates that fluid gain occurred during the Giro d'Italia. This fluid gain was not reflected by body weight measurements and might be mainly attributed to muscle edema and/or haemodilution. Furthermore, power output and RPE, mostly depending on team tactic, were not affected by the body water increases.

The Effect of Culture on Human Bone Marrow Mesenchymal Stem Cells: Focus on DNA Methylation Profiles.

Human bone marrow mesenchymal stem cells (hBM-MSCs) are the best characterized multipotent adult stem cells. Their self-renewal capacity, multilineage differentiation potential, and immunomodulatory properties have indicated that they can be used in many clinical therapies. In a previous work we studied the DNA methylation levels of hBM-MSC genomic DNA in order to delineate a kind of methylation signature specific for early and late passages of culture. In the present work we focused on the modification of the methylation profiles of the X chromosome and imprinted loci, as sites expected to be more stable than whole genome. We propose a model where cultured hBM-MSCs undergo random modifications at the methylation level of most CGIs, nevertheless reflecting the original methylation status. We also pointed out global genome-wide demethylation connected to the long-term culture and senescence. Modification at CGIs promoters of specific genes could be related to the decrease in adipogenic differentiation potential. In conclusion, we showed important changes in CGIs methylation due to long-term in vitro culture that may affect the differentiation potential of hBM-MSCs. Therefore it is necessary to optimize the experimental conditions for in vitro expansion in order to minimize these epigenetic changes and to standardize safer procedures.

Human Mesenchymal Stem Cells Protect Dorsal Root Ganglia from the Neurotoxic Effect of Cisplatin.

BACKGROUND/AIM: Peripheral neurotoxicity is a dose-limiting factor of many chemotherapeutic agents, including cisplatin. Mesenchymal stem cells are promising for the treatment of several neurological disorders, and our aim was to verify the neuroprotective potential of human mesenchymal stem cells (hMSCs) on dorsal root ganglia (DRG) exposed to cisplatin. MATERIALS AND METHODS: DRG were exposed to different cisplatin concentrations and then co-cultured with hMSCs or with hMSC-conditioned medium. RESULTS: hMSCs showed a neuroprotective effect on cisplatin-induced death of DRG, mediated by direct contact. Moreover, DRG exhibited an MSC-dependent promotion of neurite outgrowth, in particular at early time points. For this effect, the expression of Neurite Outgrowth Inhibitor (NOGO) and Myelin Associated Glycoprotein (MAG) by hMSCs was pivotal. CONCLUSION: hMSCs are a promising tool for reducing the neurotoxic effect of cisplatin.

Neurobasal medium toxicity on mature cortical neurons.

Neurobasal medium (NBM) is a widely used medium for neuronal cultures, originally formulated to support survival of rat hippocampal neurons, but then optimized for several other neuronal subtypes. In the present study, the toxic effect of NBM on long-term cortical neuron cultures has been reported and investigated. A significant neuronal cell loss was observed 24 h after the total medium change performed at days in vitro 10. The neurotoxic effect was specifically because of NBM-A, a commercially derived modification of classic NBM, as neurons exposed to minimum essential medium for 24 h did not show the same mortality rate. We showed that the toxic effect was mediated by the N-methyl-D-aspartate receptor (NMDAr) as its inactivation partly prevented NBM-induced neuronal loss, and the addition of NMDAr activators, such as L-cysteine or glycine to minimum essential medium, reproduced the same toxicity rate observed in NBM. Besides the toxicity associated with NMDAr activation, the decreased antioxidative defenses also worsen (because of glutathione depletion) neuronal death, thus amplifying the effect of excitotoxic amino acids. Indeed, glutathione supplementation by the addition of its precursor N-acetyl-cysteine resulted in an increase in neuronal survival that partially prevented NBM-A toxicity. These results evidenced, on the one hand, the unsuitability of NBM-A for long-term neuronal culture, and on the other, they highlight the importance of selection of more suitable culture conditions.

Stem cell augmented mesh materials: an in vitro and in vivo study.

INTRODUCTION AND HYPOTHESIS: To test in vitro and in vivo the capability of mesh materials to act as scaffolds for rat-derived mesenchymal stem cells (rMSCs) and to compare inflammatory response and collagen characteristics of implant materials, either seeded or not with rMSCs. METHODS: rMSCs isolated from rat bone marrow were seeded and cultured in vitro on four different implant materials. Implants showing the best rMSC proliferation rate were selected for the in vivo experiment. Forty-eight adult female Sprague-Dawley rats were randomly divided into two treatment groups. The implant of interest-either seeded or not with rMSCs-was laid and fixed over the muscular abdominal wall. Main outcome measures were: in vitro, proliferation of rMSCs on selected materials; in vivo, the occurrence of topical complications, the evaluation of systemic and local inflammatory response and examination of the biomechanical properties of explants. RESULTS: Surgisis and Pelvitex displayed the best cell growth in vitro. At 90 days in the rat model, rMSCs were related to a lower count of neutrophil cells for Pelvitex and a greater organisation and collagen amount for Surgisis. At 7 days Surgisis samples seeded with rMSCs displayed higher breaking force and stiffness. CONCLUSIONS: The presence of rMSCs reduced the systemic inflammatory response on synthetic implants and improved collagen characteristics at the interface between biological grafts and native tissues. rMSCs enhanced the stripping force on biological explants.

Mesengenic differentiation: comparison of human and rat bone marrow mesenchymal stem cells.

BACKGROUND AND OBJECTIVES: Cellular therapies using Mesenchymal Stem Cells (MSCs) represent a promising approach for the treatment of degenerative diseases, in particular for mesengenic tissue regeneration. However, before the approval of clinical trials in humans, in vitro studies must be performed aimed at investigating MSCs' biology and the mechanisms regulating their proliferation and differentiation abilities. Besides studies on human MSCs (hMSCs), MSCs derived from rodents have been the most used cellular type for in vitro studies. Nevertheless, the transfer of the results obtained using animal MSCs to hMSCs has been hindered by the limited knowledge regarding the similarities existing between cells of different origins. Aim of this paper is to highlight similarities and differences and to clarify the sometimes reported different results obtained using these cells. METHODS AND RESULTS: We compare the differentiation ability into mesengenic lineages of rat and human MSCs cultured in their standard conditions. Our results describe in which way the source from which MSCs are derived affects their differentiation potential, depending on the mesengenic lineage considered. For osteogenic and chondrogenic lineages, the main difference between human and rat MSCs is represented by differentiation time, while for adipogenesis hMSCs have a greater differentiation potential. CONCLUSIONS: These results on the one hand suggest to carefully evaluate the transfer of results obtained with animal MSCs, on the other hand they offer a clue to better apply MSCs into clinical practice.

Relationships between cobalamin, epidermal growth factor, and normal prions in the myelin maintenance of central nervous system.

Cobalamin (Cbl), epidermal growth factor (EGF), and prions (PrPs) are key molecules for myelin maintenance in the central and peripheral nervous systems. Cbl and EGF increase normal prion (PrP(C)) synthesis and PrP(C) levels in rat spinal cord (SC) and elsewhere. Cbl deficiency increases PrP(C) levels in rat SC and cerebrospinal fluid (CSF), and decreases PrP(C)-mRNA levels in rat SC. The administration of anti-octapeptide repeat PrP(C) region antibodies (Abs) to Cbl-deficient (Cbl-D) rats prevents SC myelin lesions and a local increase in tumor necrosis factor (TNF)-α levels, whereas anti-TNF-α Abs prevent SC myelin lesions and the increase in SC and CSF PrP(C) levels. As it is known that both Cbl and EGF regulate SC PrP(C) synthesis independently, and that Cbl regulates SC EGF synthesis, EGF may play both Cbl-independent and Cbl-dependent roles. When Cbl-D rats undergo Cbl replacement therapy, SC PrP(C) levels are similar to those observed in Cbl-D rats. In rat frontal cortex (which is marginally affected by Cbl deficiency in histological terms), Cbl deficiency decreases PrP(C) levels and the increase induced by Cbl replacement leads to their normalization. Increased nerve PrP(C) levels are detected in the myelin lesions of the peripheral neuropathy of Cbl-D rats, and CSF PrP(C) levels are also increased in Cbl-D patients (but not in patients with Cbl-unrelated neurological diseases). Various common steps in the downstream signaling pathway of Cbl, EGF, and PrP(C) underlines the close relationship between the three molecules in keeping myelin normal.

Expression of neural markers by undifferentiated mesenchymal-like stem cells from different sources.

The spontaneous expression of neural markers, already demonstrated in bone marrow (BM) mesenchymal stem cells (MSCs), has been considered as evidence of the MSCs' predisposition to differentiate toward neural lineages, supporting their use in stem cell-based therapy for neural repair. In this study we have evaluated, by immunocytochemistry, immunoblotting, and flow cytometry experiments, the expression of neural markers in undifferentiated MSCs from different sources: human adipose stem cells (hASCs), human skin-derived mesenchymal stem cells (hS-MSCs), human periodontal ligament stem cells (hPDLSCs,) and human dental pulp stem cells (hDPSCs). Our results demonstrate that the neuronal markers ß III-tubulin and NeuN, unlike other evaluated markers, are spontaneously expressed by a very high percentage of undifferentiated hASCs, hS-MSCs, hPDLSCs, and hDPSCs. Conversely, the neural progenitor marker nestin is expressed only by a high percentage of undifferentiated hPDLSCs and hDPSCs. Our results suggest that the expression of ß III-tubulin and NeuN could be a common feature of stem cells and not exclusive to neuronal cells. This could result in a reassessment of the use of ß III-tubulin and NeuN as the only evidence proving neuronal differentiation. Further studies will be necessary to elucidate the relevance of the spontaneous expression of these markers in stem cells.

A double mechanism for the mesenchymal stem cells' positive effect on pancreatic islets.

The clinical usability of pancreatic islet transplantation for the treatment of type I diabetes, despite some encouraging results, is currently hampered by the short lifespan of the transplanted tissue. In vivo studies have demonstrated that co-transplantation of Mesenchymal Stem Cells (MSCs) with transplanted pancreatic islets is more effective with respect to pancreatic islets alone in ensuring glycemia control in diabetic rats, but the molecular mechanisms of this action are still unclear. The aim of this study was to elucidate the molecular mechanisms of the positive effect of MSCs on pancreatic islet functionality by setting up direct, indirect and mixed co-cultures. MSCs were both able to prolong the survival of pancreatic islets, and to directly differentiate into an "insulin-releasing" phenotype. Two distinct mechanisms mediated these effects: i) the survival increase was observed in pancreatic islets indirectly co-cultured with MSCs, probably mediated by the trophic factors released by MSCs; ii) MSCs in direct contact with pancreatic islets started to express Pdx1, a pivotal gene of insulin production, and then differentiated into insulin releasing cells. These results demonstrate that MSCs may be useful for potentiating pancreatic islets' functionality and feasibility.

DNA Methylation Changes during In Vitro Propagation of Human Mesenchymal Stem Cells: Implications for Their Genomic Stability?

Mesenchymal stem cells (MSCs) hold great promise for the treatment of numerous diseases. A major problem for MSC therapeutic use is represented by the very low amount of MSCs which can be isolated from different tissues; thus ex vivo expansion is indispensable. Long-term culture, however, is associated with extensive morphological and functional changes of MSCs. In addition, the concern that they may accumulate stochastic mutations which lead the risk of malignant transformation still remains. Overall, the genome of human MSCs (hMSCs) appears to be apparently stable throughout culture, though transient clonal aneuploidies have been detected. Particular attention should be given to the use of low-oxygen environment in order to increase the proliferative capacity of hMSCs, since data on the effect of hypoxic culture conditions on genomic stability are few and contradictory. Furthermore, specific and reproducible epigenetic changes were acquired by hMSCs during ex vivo expansion, which may be connected and trigger all the biological changes observed. In this review we address current issues on long-term culture of hMSCs with a 360-degree view, starting from the genomic profiles and back, looking for an epigenetic interpretation of their genetic stability.

Undifferentiated MSCs are able to myelinate DRG neuron processes through p75.

Over the last few years the therapeutic approach to demyelinating diseases has radically changed, strategies having been developed aimed at partnering the classic symptomatic treatments with the most advanced regenerative medicine tools. At first, the transplantation of myelinogenic cells, Schwann cells or oligodendrocytes was suggested, but the considerable technical difficulties, (poor availability, difficulties in harvesting and culturing, and the problem of rejection in the event of non-autologous sources), shifted attention towards more versatile cellular types, such as Mesenchymal Stem Cells (MSCs). Recent studies have already demonstrate both in vitro and in vivo that glially-primed MSCs (through exposure to chemical cocktails) have myelogenic abilities. In spite of a large number of papers on glially-differentiated MSCs, little is known about the ability of undifferentiated MSCs to myelinate axons and processes. Here we have demonstrated that also undifferentiated MSCs have the ability to myelinate, since they induce the myelination of rat DRG neuron processes after direct co-culturing. In this process a pivotal role is performed by the p75 receptor.

Human mesenchymal stem cells express neuronal markers after osteogenic and adipogenic differentiation.

Mesenchymal stem cells (MSCs) are multipotent cells that are able to differentiate into mesodermal lineages (osteogenic, adipogenic, chondrogenic), but also towards non-mesodermal derivatives (e.g. neural cells). Recent in vitro studies revealed that, in the absence of any kind of differentiation stimuli, undifferentiated MSCs express neural differentiation markers, but the literature data do not all concur. Considering their promising therapeutic potential for neurodegenerative diseases, it is very important to expand our knowledge about this particular biological property of MSCs. In this study, we confirmed the spontaneous expression of neural markers (neuronal, glial and progenitor markers) by undifferentiated human MSCs (hMSCs) and in particular, we demonstrated that the neuronal markers ßIII-tubulin and NeuN are expressed by a very high percentage of hMSCs, regardless of the number of culture passages and the culture conditions. Moreover, the neuronal markers ßIII-tubulin and NeuN are still expressed by hMSCs after in vitro osteogenic and adipogenic differentiation. On the other hand, chondrogenically differentiated hMSCs are negative for these markers. Our findings suggest that the expression of neuronal markers could be common to a wide range of cellular types and not exclusive for neuronal lineages. Therefore, the expression of neuronal markers alone is not sufficient to demonstrate the differentiation of MSCs towards the neuronal phenotype. Functional properties analysis is also required.

From cytogenomic to epigenomic profiles: monitoring the biologic behavior of in vitro cultured human bone marrow mesenchymal stem cells.

INTRODUCTION: Bone marrow mesenchymal stem cells (BM-MSCs) are multipotent cells that can differentiate into different cell lineages and have emerged as a promising tool for cell-targeted therapies and tissue engineering. Their use in a therapeutic context requires large-scale in vitro expansion, increasing the probability of genetic and epigenetic instabilities. Some evidence shows that an organized program of replicative senescence is triggered in human BM-MSCs (hBM-MSCs) on prolonged in vitro expansion that includes alterations in phenotype, differentiation potential, telomere length, proliferation rates, global gene-expression patterns, and DNA methylation profiles. METHODS: In this study, we monitored the chromosomal status, the biologic behavior, and the senescence state of hBM-MSCs derived from eight healthy donors at different passages during in vitro propagation. For a more complete picture, the telomere length was also monitored in five of eight donors, whereas the genomic profile was evaluated in three of eight donors by array-comparative genomic hybridization (array-CGH). Finally, an epigenomic profile was delineated and compared between early and late passages, by pooling DNA of hBM-MSCs from four donors. RESULTS: Our data indicate that long-term culture severely affects the characteristics of hBM-MSCs. All the observed changes (that is, enlarged morphology, decreased number of cell divisions, random loss of genomic regions, telomere shortening) might be regulated by epigenetic modifications. Gene Ontology analysis revealed that specific biologic processes of hBM-MSCs are affected by variations in DNA methylation from early to late passages. CONCLUSIONS: Because we revealed a significant decrease in DNA methylation levels in hBM-MSCs during long-term culture, it is very important to unravel how these modifications can influence the biologic features of hBM-MSCs to keep track of this organized program and also to clarify the conflicting observations on hBM-MSC malignant transformation in the literature.

Expression of neural markers by undifferentiated rat mesenchymal stem cells.

The spontaneous expression of neural markers by mesenchymal stem cells (MSCs) has been considered to be a demonstration of MSCs' predisposition to differentiate towards neural lineages. In view of their application in cell therapy for neurodegenerative diseases, it is very important to deepen the knowledge about this distinctive biological property of MSCs. In this study, we evaluated the expression of neuronal and glial markers in undifferentiated rat MSCs (rMSCs) at different culture passages (from early to late). rMSCs spontaneously expressed neural markers depending on culture passage, and they were coexpressed or not with the neural progenitor marker nestin. In contrast, the number of rMSCs expressing mesengenic differentiation markers was very low or even completely absent. Moreover, rMSCs at late culture passages were not senescent cells and maintained the MSC immunophenotype. However, their differentiation capabilities were altered. In conclusion, our results support the concept of MSCs as multidifferentiated cells and suggest the existence of immature and mature neurally fated rMSC subpopulations. A possible correlation between specific MSC subpopulations and specific neural lineages could optimize the use of MSCs in cell transplantation therapy for the treatment of neurological diseases.

Monitoring techniques for prevention of procedure-related ischemic damage in aneurysm surgery.

OBJECTIVE: To describe the application of intraoperative monitoring techniques during aneurysm surgery and to discuss the advantages and limitations of these techniques in prevention of postoperative neurologic deficits. METHODS: Articles found in the literature through PubMed for the time frame 1980-2011 and the authors' personal files were reviewed. RESULTS: Various techniques for detection of vascular insufficiency are available, including direct methods to measure cerebral blood flow and indirect methods to evaluate the integrity of neurologic pathways. CONCLUSIONS: The choice of monitoring modality should be governed by the vessel and by the vascular territory most at risk during the planned procedure with proper awareness of the potential limits related to each technique. Aneurysm surgery monitoring should help to address issues of continuity and provide a morphologic and functional assessment. Although the use of monitoring devices is still not routine in aneurysm surgery and no standards have been established, combining different monitoring techniques is crucial to optimize aneurysm surgery and avoid or minimize complications.

Cobalamin (vitamin B(12)) regulation of PrP(C), PrP(C)-mRNA and copper levels in rat central nervous system.

The pathogenesis of cobalamin (Cbl)-deficient (Cbl-D) neuropathy is not clear, nor is the role of prions (PrP(C)) in myelin maintenance. However, as it is known that Cbl deficiency damages myelin by increasing tumor necrosis factor (TNF)-α and decreasing epidermal growth factor (EGF) levels in rat spinal cord (SC), and that TNF-α and EGF regulate PrP(C) expression in vitro, we investigated whether Cbl deficiency modifies SC PrP(C) and PrP(C)-mRNA levels in Cbl-D rats. PrP(C) levels had increased by the time myelin lesions appeared. This increase was mediated by excess myelinotoxic TNF-α and prevented by EGF, which proved to be as effective as Cbl in preventing Cbl deficiency-induced lesions. There were no significant changes in hepatic PrP(C) levels of Cbl-D rats. Anti-octapeptide repeat (OR) region antibodies normalized SC myelin morphology. Cbl deficiency greatly reduced SC PrP(C)-mRNA levels, which were subsequently increased by Cbl and EGF. Cbl deficiency-induced excess OR is myelin-damaging, but new PrP(C) synthesis is a common effect of different myelinotrophic agents.