Biomedical subjects

D K Anderson

Publications and source records attributed to D K Anderson.

At least 19 recordsLinked to original sources

PubMed1998

Developmental patterns of BCL-2 and BCL-X polypeptide expression in the human spinal cord.

The cell death suppressors bcl-2 and bcl-x are developmentally regulated and may modulate physiologic cell death in the central nervous system (CNS). However, little data are currently available on the expression patterns of these polypeptides in the human CNS. We examined the ontogeny of bcl-2 and bcl-x in 12 human spinal cords of gestational ages (GA) between 5 and 39 weeks and in 3 adult cords. Paraffin sections were probed by immunohistochemistry using well-characterized, commercially available antibodies that had been raised against poorly conserved epitopes of these homologous proteins. Between 5 and 10 weeks GA, bcl-2 immunoreactivity was identified in primitive neuroepithelial cells of the ventricular zone. Individual cells of the mantle zone were stained including clusters of early anterior horn cells. Bcl-x immunoreactivity was most prominent in differentiating neurons of the mantle zone and less pronounced in the ventricular zone. Between 10 and 14 weeks GA, bcl-2 staining was observed in cells lining the central canal, neurons of the dorsal horn (especially laminae I and II), and in anterior horn cells. The latter exhibited a range of staining intensities from moderate to nondetectable. Bcl-2 immunoreactivity became markedly reduced between 15 and 25 weeks GA, persisting only in ependymal cells. In contrast, strong bcl-x staining was observed in most neurons throughout development and into adulthood. The period of apparent bcl-2 down-regulation overlaps with a peak in physiologic motoneuron death and the establishment of functional neuromuscular synapses in the human spinal cord. These findings suggest that bcl-2 and bcl-x may both be required for survival of early postmitotic neurons before appropriate synaptic connections have been established. Continued neuronal survival (after bcl-2 is down-regulated) may require persistent bcl-x expression in addition to target-derived neurotrophic factors made available through the formation of appropriate synapses.

Adult↗

PubMed1998

Erythropoietin and erythropoietin receptor in the developing human central nervous system.

We have previously shown the presence of erythropoietin (Epo) within the spinal fluid of normal preterm and term infants, and the presence of Epo receptor (Epo-R) in the spinal cords of human fetuses. It is not known, however: 1) whether cells within the fetal central nervous system (CNS) express Epo; 2) if so, whether this expression changes with development; 3) which cells within the CNS express Epo-R; 4) whether Epo-R expression within the CNS changes with development; and 5) whether Epo-R within the fetal CNS are functional. Expression of mRNA for Epo and Epo-R was sought by reverse transcription-PCR in mixed primary cultures of fetal spinal cords as well as NT2 and hNT cells, human cell lines of neuronal precursors and mature neurons, respectively. Epo was measured by ELISA in spent media from primary cell culture, and immunohistochemistry was used to identify Epo-R on neurons and glia in cell culture, and in brain sections. Developmental changes in Epo and Epo-R expression were sought in spinal cords and brains from fetuses of 7-24 wk postconception by semiquantitative PCR. To assess Epo-R function, NT2 cells were exposed to conditions which stimulate programmed cell death, and rescue from apoptosis by the addition of recombinant Epo was evaluated by nuclear matrix protein ELISA, cell counts, and by Klenow labeling of DNA fragments. Epo and Epo-R mRNA were expressed in mixed primary cultures of neural tissues and NT2 and hNT cells. Epo was detected by ELISA in media removed from mixed cell cultures, and immunohistochemical staining confirmed the presence of Epo-R on neurons and their supporting cells. Semiquantitative PCR revealed no significant change in expression of either Epo or Epo-R in spinal cords between 7 and 16 wk of gestation, with increased expression of Epo and Epo-R in brains from 8 to 24 wk of gestation. Epo mRNA expression from neurons doubled under conditions of hypoxia. Recombinant Epo decreased apoptotic cell death of neurons under conditions of hypoxia. Protein and mRNA for Epo and its receptor are expressed by human neurons and glial cells in spinal cord and brain during fetal development. These receptors appear to have a neuroprotective effect in conditions of hypoxia.

Central Nervous System↗

PubMed1997

Immunocytochemical method for investigating in vivo neuronal oxygen radical-induced lipid peroxidation.

The investigation of oxygen radical-induced lipid peroxidative neuronal damage in the context of acute and chronic neurodegenerative disorders has been largely limited to the use of ex vivo analytical methodologies. These are often fraught with sensitivity or specificity problems, or they are indirect. Furthermore, none of the analytical methods allow precise anatomical identification of the cells that are undergoing peroxidative injury. This paper describes an immunocytochemical method for localization of central nervous system (CNS) lipid peroxidation (LP) that employs a rabbit-derived antibody raised against malondialdehyde (MDA)-modified rabbit serum albumin (RSA). MDA is a breakdown product of peroxidized membrane polyunsaturated fatty acids that avidly binds to cellular proteins. Using the anti-MDA-RSA, we herein illustrate increased MDA-derived immunostaining: (1) in the spinal cord of transgenic familial amyotrophic lateral sclerosis (ALS) mice; and (2) in the selectively vulnerable gerbil hippocampal CA1 region after a 5 min episode of forebrain ischemia and its relationship to the time course of neuronal degeneration.

Amyotrophic Lateral Sclerosis↗

PubMed1997

Endogenous repair after spinal cord contusion injuries in the rat.

Contusion injuries of the rat thoracic spinal cord were made using a standardized device developed for the Multicenter Animal Spinal Cord Injury Study (MASCIS). Lesions of different severity were studied for signs of endogenous repair at times up to 6 weeks following injury. Contusion injuries produced a typical picture of secondary damage resulting in the destruction of the cord center and the chronic sparing of a peripheral rim of fibers which varied in amount depending upon the injury magnitude. It was noted that the cavities often developed a dense cellular matrix that became partially filled with nerve fibers and associated Schwann cells. The amount of fiber and Schwann cell ingrowth was inversely related to the severity of injury and amount of peripheral fiber sparing. The source of the ingrowing fibers was not determined, but many of them clearly originated in the dorsal roots. In addition to signs of regeneration, we noted evidence for the proliferation of cells located in the ependymal zone surrounding the central canal at early times following contusion injuries. These cells may contribute to the development of cellular trabeculae that provide a scaffolding within the lesion cavity that provides the substrates for cellular infiltration and regeneration of axons. Together, these observations suggest that the endogenous reparative response to spinal contusion injury is substantial. Understanding the regulation and restrictions on the repair processes might lead to better ways in which to encourage spontaneous recovery after CNS injury.

Animals↗

PubMed1997

Characteristics of human fetal spinal cord grafts in the adult rat spinal cord: influences of lesion and grafting conditions.

The present study evaluated the growth potential and differentiation of human fetal spinal cord (FSC) tissue in the injured adult rat spinal cord under different lesion and grafting conditions. Donor tissue at 6-9 weeks of gestational age was obtained through elective abortions and transplanted either immediately into acute resection (solid grafts) or into chronic contusion (suspension and solid grafts) lesions (i.e., 14-40 days after injury) in the thoracic spinal cord. The xenografts were then examined either histologically in plastic sections or immunocytochemically 1-3 months postgrafting. Intraspinal grafts in acute lesions demonstrated an 83% survival rate and developed as well-circumscribed nodules that were predominantly composed of immature astrocytes. Solid-piece grafts in chronic contusion lesions exhibited a 92% survival rate and also developed as nodular masses. These grafts, however, contained many immature neurons 2 months postgrafting. Suspension grafts in chronic contusion lesions had an 85% survival rate and expanded in a nonrestrictive, diffuse pattern. These transplants demonstrated large neuronally rich areas of neural parenchyma. Extensive neuritic outgrowth could also be seen extending from these grafts into the surrounding host spinal cord. These findings show that human FSC tissue reliably survives and differentiates in both acute and chronic lesions. However, both the lesion environment and the grafting techniques can greatly influence the pattern of differentiation and degree of host-graft integration achieved.

Animals↗

PubMed1997

Posttranscriptional regulation of Caulobacter flagellin genes by a late flagellum assembly checkpoint.

Flagellum formation in Caulobacter crescentus requires ca. 50 flagellar genes, most of which belong to one of three classes (II, III, or IV). Epistasis experiments suggest that flagellar gene expression is coordinated with flagellum biosynthesis by two assembly checkpoints. Completion of the M/S ring-switch complex is required for the transition from class II to class III gene expression, and completion of the basal body-hook structure is required for the transition from class III to class IV gene expression. In studies focused on regulation of the class IV flagellin genes, we have examined fljK and fljL expression in a large number of flagellar mutants by using transcription and translation fusions to lacZ, nuclease S1 assays, and measurements of protein stability. The fljK-lacZ and fljL-lacZ transcription fusions were expressed in all class III flagellar mutants, although these strains do not make detectable 25- or 27-kDa flagellins. The finding that the fljK-lacZ translation fusion was not expressed in the same collection of class III mutants confirmed that fljK is regulated posttranscriptionally. The requirement of multiple class III genes for expression of the fljK-lacZ fusion suggests that completion of the basal body-hook is an assembly checkpoint for the posttranscriptional regulation of this flagellin gene. Deletion analysis within the 5' untranslated region of fljK identified a sequence between +24 and +38 required for regulation of the fljK-lacZ fusion by class III genes, which implicates an imperfect 14-bp direct repeat in the posttranscriptional regulation of fljK. Our results show that fljL is also regulated posttranscriptionally by class III and unclassified flagellar genes, apparently by a mechanism different from the one regulating fljK.

Bacterial Proteins↗

PubMed1997

Experimental infection of cynomolgus monkeys with simian parvovirus.

Simian parvovirus is a recently discovered parvovirus that was first isolated from cynomolgus monkeys. It is similar to human B19 parvovirus in terms of virus genome, tropism for erythroid cells, and characteristic pathology in natural infections. Cynomolgus monkeys were infected with simian parvovirus to investigate their potential usefulness as an animal model of human B19 parvovirus. Six adult female cynomolgus monkeys were inoculated with purified simian parvovirus by the intravenous or intranasal route and monitored for evidence of clinical abnormalities; this included the preparation of complete hematological profiles. Viremia and simian parvovirus-specific antibody were determined in infected monkeys by dot blot and Western blot assays, respectively. Bone marrow was examined at necropsy 6, 10, or 15 days postinfection. All of the monkeys developed a smoldering, low-grade viremia that peaked approximately 10 to 12 days after inoculation. Peak viremia coincided with the appearance of specific antibody and was followed by sudden clearance of the virus and complete, but transient, absence of reticulocytes from the peripheral blood. Clinical signs were mild and involved mainly anorexia and slight weight loss. Infection was associated with a mild decrease in hemoglobin, hematocrit, and erythrocyte numbers. Bone marrow showed marked destruction of erythroid cells coincident with peak viremia. Our findings indicate that infection of healthy monkeys by simian parvovirus is self-limited and mild, with transient cessation of erythropoiesis. Our study has reproduced Koch's postulates and further shown that simian parvovirus infection of monkeys is almost identical to human B19 parvovirus infection of humans. Accordingly, this animal model may prove valuable in the study of the pathogenesis of B19 virus infection.

Animals↗

PubMed1997

Fatal disseminated cercopithecine herpesvirus 1 (herpes B infection in cynomolgus monkeys (Macaca fascicularis).

Two adult female cynomolgus monkeys (Macaca fascicularis) that had been housed together for 4 months died within 2 weeks of each other after brief illnesses. Monkey No. 1 presented with collapse, watery stool, and hypothermia and died overnight. Monkey No. 2 presented with dyspnea, nasal discharge, leukopenia, and hypoproteinemia and was euthanized after 2 days. Both animals had peritoneal effusions, massive necrosis of pharyngeal, esophageal, and gastric mucosa, and multifocal hepatic and pancreatic necrosis. Monkey No. 2 also had lingual ulcers and locally extensive necrosis of spleen, adrenal glands, and lymph nodes. Large numbers of eosinophilic intranuclear inclusion bodies were present in epithelial and syncytial cells adjoining the necrotic foci in Monkey No. 2 but were absent in Monkey No. 1. Monkey No. 1 seroconverted to cercopithecine herpesvirus 1 (CHV-1, commonly known as herpes B) in the month before death. CHV-1 was isolated from a sample of stomach from Monkey No. 2, and electron microscopy of liver from this animal demonstrated herpesvirus particles within hepatocytes. Both animals were seropositive for simian type D retrovirus, and the virus was cultured from the liver of Monkey No. 2. A diagnosis of disseminated CHV-1 infection was made, possibly occurring secondary to immunosuppression due to infection with simian type D retrovirus. Although a high percentage of cynomolgus monkeys are apparently infected with CHV-1, disseminated disease is rare. Because infection with CHV-1 in humans is associated with a high fatality rate, familiarity with the lesions of disseminated infection with this virus is important.

Adrenal Glands↗

PubMed1996

Effects of methylprednisolone on the GABA- and glutamate-induced currents: relevance to glucocorticoid-induced neurotoxicity and brain aging.

We have previously shown that both epidural administration and microinjection of methylprednisolone (MP) produces neuronal hyperexcitability in the murine spinal cord in vivo. In this study, the whole-cell patch-clamp technique was used to describe and characterize MP-induced neuronal hyperexcitability. Exposure of 10- to 18-day old dissociated spinal cord cultures to 65 microM-8 mM MP caused a concentration-dependent increase in the firing rate. MP (1 mM) increased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) and spontaneous inhibitory postsynaptic currents (sIPSCs). The amplitude of the sEPSCs was also increased in response to 1 mM MP, whereas sIPSCs became smaller in size in the presence of MP. MP (1 mM) reduced the amplitude of the gamma-aminobutyric acid (GABA)-induced currents, whereas it increased the amplitude of the glutamate-induced currents. And finally; MP (1 mM), by itself, did not change the overall postsynaptic membrane conductance. These observations suggest that (1) MP can act as an excitatory agent in vitro, (2) it can act at the presynaptic as well as the postsynaptic level, and (3) it affects spinal cord neurons by influencing the ligand-gated (GABA and glutamate) channels.

Administration, Topical↗

PubMed1996

MASCIS evaluation of open field locomotor scores: effects of experience and teamwork on reliability. Multicenter Animal Spinal Cord Injury Study.

The Multicenter Animal Spinal Cord Injury Study (MASCIS) adopted a modified 21-point open field locomotor scale developed by Basso, Beattie, and Bresnahan (BBB) at Ohio State University (OSU) to measure motor recovery in spinal-injured rats. BBB scores categorize combinations of rat hindlimb movements, trunk position and stability, stepping, coordination, paw placement, toe clearance, and tail position, representing sequential recovery stages that rats attain after spinal cord injury. A total of 22 observers from 8 participating centers assessed 18 hindlimbs of 9 rats at 2-6 weeks after graded spinal cord injury. The observers were segregated into 10 teams. The teams were grouped into 3 cohorts (A, B, and C), consisting of one experienced team from OSU and two non-OSU teams. The cohorts evaluated the rats in three concurrent and sequential sessions. After viewing a rat for 4 min, individual observers first assigned scores without discussion. Members of each team then discussed and assigned a team score. Experience (OSU vs. non-OSU) and teamwork (individual vs. team) had no significant effect on mean scores although the mean scores of one cohort differed significantly from the others (p = 0.0002, ANOVA). However, experience and teamwork significantly influenced reliability of scoring. OSU team scores had a mean standard deviation or discordance of 0.59 points, significantly less than 1.31 points for non-OSU team scores (p = 0.003, ANOVA) and 1.30 points for non-OSU individual scores (p = 0.001, ANOVA). Discordances were greater at the upper and lower ends of the scale, exceeding 2.0 in the lower (< 5) and upper (> 15) ends of the scale but were < 1.0 for scores between 4 and 16. Comparisons of non-OSU and OSU team scores indicated a high reliability coefficient of 0.892 and a correlation index (r2) of 0.894. These results indicate that inexperienced observers can learn quickly to assign consistent BBB scores that approach those given by experienced teams, that the scores are most consistent between 4 and 16, and that experience improves consistency of team scores.

Animals↗

PubMed1996

Clinical and epidemiological features of simian parvovirus infection in cynomolgus macaques with severe anemia.

We recently identified a simian parvovirus (SPV) in cynomolgus monkeys with severe anemia. We describe here the clinical and epidemiological findings in the original outbreak and in a second episode of anemia involving monkeys in a drug safety study at a separate facility. The major clinical findings associated with SPV infection were a severe normocytic, normochromic anemia. In the original episode the anemia was predominantly nonregenerative, whereas in the second outbreak there was an initial strong, regenerative response. In the absence of predisposing factors, SPV infection was mild or inapparent. However, the presence of concurrent acute infection with type D simian retrovirus in the original episode is believed to have been a major predisposing factor for the development of immunodeficiency and persistent SPV infection, culminating in severe anemia. It is unclear whether simian retrovirus infection played a role in the second episode, but it is possible that the drug used may have been a factor, because severely anemic monkeys were in the high drug dosage group. We conclude that SPV should be considered in the differential diagnosis of severe anemia in monkeys.

Anemia↗

PubMed1995

Regulation of the Caulobacter crescentus rpoN gene and function of the purified sigma 54 in flagellar gene transcription.

The sequential transcription of flagellar (fla) genes in the Caulobacter crescentus cell cycle is controlled by the organization of these genes in a regulatory hierarchy of four levels (I-IV). Level III and level IV genes at the bottom of the hierarchy are dependent on level II genes and are transcribed late in the cell cycle from sigma 54-dependent promoters. To study the regulation of genes at levels III and IV, we have isolated and sequenced the rpoN gene in order to analyze its expression, purified the rpoN gene product, and examined the role of the RpoN protein in initiation of transcription from sigma 54-dependent promoters. We report here epistasis experiments that show rpoN is required for transcription of level III genes, but that the expression of the rpoN gene itself is not dependent on any of the fla genes examined; these results place rpoN at level II near the top of the hierarchy. Consistent with this conclusion were nuclease S1 assays that mapped the rpoN transcription start site and identified a sequence centered at -24, GTTA/TACCA/TT, which is similar to the core consensus sequence of the level IIB fliF, fliL, and fliQ promoters. We purified the full-length rpoN gene product to near homogeneity and demonstrated that the RpoN protein is required for transcription from the well-characterized sigma 54-dependent glnAp2 promoter of Escherichia coli and specifically recognizes the level III flbG gene promoter of C. crescentus. These last results confirm that rpoN encodes the C. crescentus sigma 54 factor and opens the way for the biochemical analysis of transcriptional regulation of level III and IV fla genes.

Amino Acid Sequence↗

PubMed1995

Dynamic assessment of intraspinal neural graft survival using magnetic resonance imaging.

Although previous work has demonstrated the usefulness of magnetic resonance imaging (MRI) for visualizing intraspinal transplants in vivo, the degree to which MRI can differentiate viable fetal neural tissue from evolving spinal cord pathology has not been investigated. Thus, the present study assessed whether MRI performed at earlier postgrafting intervals (0-20 weeks) could document the survival of fetal neural transplants in the injured cat spinal cord. Twelve adult female cats received a hemisection injury at the L1 level, followed immediately by implantation of either embryonic cat spinal cord or neocortex into the cavity. The spinal cords of three control animals were hemisected but received no transplant. Each animal was subsequently imaged at 4 and 8 weeks postoperative. Selected animals from each group were also studied at additional time points ranging from immediately postoperative to 20 weeks. Multislice T2-weighted and intermediate T1-weighted spin-echo images of the lesion or graft site were obtained. Correlative postmortem histological analyses revealed viable donor tissue in 6 of 12 transplant recipients. Spinal cords from the remaining hosts and the control animals all contained cysts at the surgical site that were devoid of donor neural tissue. The graft sites with viable tissue tended to exhibit a slightly hyperintense signal on both intermediate T1-weighted (T1WI) and T2-weighted images (T2WI) throughout the entire experiment. Control cats and cats with failed transplants also were slightly bright on T1WI, but were very hyperintense on T2WI.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Measurement of vascular permeability in spinal cord using Evans Blue spectrophotometry and correction for turbidity.

Vascular permeability can be visualized by Evans Blue (EB) extravasation and quantified by spectrophotometry after formamide extraction of the tissue. However, formamide extracts show significant turbidity, which may contribute to the total optical density at the wavelength of measurement (e.g., 620 lambda). We developed a simple method for estimating the component of the total optical density of a dyed specimen contributed by turbidity. Our method, which uses a determination of turbidity made at another point of the light spectrum (740 lambda), was more precise than two other EB quantification techniques. We therefore recommend it for individual correction of formamide extracts of spinal cord specimens. The application of this technique to the brain remains to be determined.

Animals↗

PubMed1995

Fetal neural grafts and repair of the injured spinal cord.

Solid or suspension grafts of fetal spinal cord (FSC), caudal brainstem (FBSt), neocortex (FNCx) or a combination of either FSC/FNCx or FSC/FBSt were placed into cavities produced by static loading (i.e., compression) of the spinal cord of adult cats two to 30 weeks after injury. Extensively vascularized, viable graft tissue was found in all animals with the exception of two cats which showed active rejection of their transplants. Surviving grafts showed many immature characteristics 6-9 weeks after transplantation. However, by 20-30 weeks, FSC and FBSt grafts were more mature. Grafts integrated with the host gray and white matter and neuritic processes from both host and graft were seen crossing the host-graft interface. Host calcitonin gene related peptide (CGRP)-like immunoreactive axons could be traced into FSC and FBSt grafts. A more restricted ingrowth of host serotonin (5-HT)-like immunoreactive fibers was seen in FSC grafts. Our results suggest that the capacity of homotypic transplants to promote recovery of function is greater than heterotypic transplants. Additionally, it appears that the functional capacity of the graft depends upon graft survival, the time interval between injury and transplantation, and whether or not the lesion cavity was debrided prior to grafting.

Animals↗

PubMed1994

Methylprednisolone and membrane properties of primary cultures of mouse spinal cord.

The present study attempts to define the capacity of methylprednisolone sodium succinate (MP) to protect neuronal membranes against a free radical challenge in primary cultures of fetal mouse spinal cord. Incubation of these cultures with MP significantly increased the Na+,K(+)-ATPase activity, an effect that was blocked by the RNA synthesis inhibitor, actinomysin D and the protein synthesis inhibitor, cycloheximide, suggesting an induction of protein synthesis by MP. In contrast, incubation with FeCl2 for 1 or 2 h significantly inhibited Na+,K(+)-ATPase activity and elevated the levels of thiobarbituric acid-reactive substances (TBARS). Pretreatment with MP prevented the rise in TBARS and partially prevented the decrease in Na+,K(+)-ATPase activity for the first hour of FeCl2 incubation, an effect that was lost during the second hour. A second dose of MP after the first hour of incubation with FeCl2 partially restored Na+,K(+)-ATPase activity and reduced TBARS levels after the second hour of exposure to FeCl2. Co-incubation of MP with cycloheximide completely prevented the decrease in Na+,K(+)-ATPase activity seen after a 2-h incubation with FeCl2 and eliminated the need for a second dose of MP after the first hour of incubation with FeCl2. These findings suggest a capacity for rapid protein induction and antioxidant activity for MP in vitro.

Animals↗

PubMed1994

Excitotoxicity of glutamate and four analogs in primary spinal cord cell cultures.

Continuous glutamate exposure produced widespread neuronal damage in mixed whole dissociated murine spinal cord cell cultures. Ethidium bromide and acridine orange staining revealed that a 24 h glutamate exposure produced nearly 98% neuronal cell death but the underlying glia were spared. Continuous exposure to glutamate, N-methyl-D-aspartate (NMDA), kainate and quisqualate produced time-dependent and dose-dependent cell death as measured by the assay of lactate dehydrogenase activity in the cell culture media. Glutamate (500 microM), NMDA (100 microM) and kainate (500 microM) were equally neurotoxic. In contrast, quisqualate (100 microM) was only partially neurotoxic compared to the other glutamate analogs. The neurotoxicity of glutamate was blocked by the NMDA antagonist, MK-801. The neurotoxicity of kainate and quisqualate was blocked with the non-NMDA antagonist CNQX. Continuous exposure to (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) was not neurotoxic, even at concentrations up to 1 mM.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed1994

Workshop on intraspinal transplantation and clinical application.

The following general conclusions were reached at the workshop: 1. Laboratory studies suggest a potential benefit of cellular transplant therapy for SCI. 2. Some evidence supporting the safety of human fetal transplants is available from clinical studies of transplants in Parkinson's disease and SCI. 3. Assessment criteria and methodology are available, including imaging approaches, validated neurologic scoring systems, detailed electrophysiologic studies of conduction and spinal cord reflexes, and functional scoring approaches. 4. More controlled animal studies are needed (a) to demonstrate efficacy and to evaluate the necessity for immunosuppressive therapy and the overall safety of intraspinal transplantation, (b) to obtain more supporting evidence (e.g., electrophysiologic, histopathologic, MRI, molecular) that would provide insights into ways that transplanted tissue could mediate function, (c) to provide guidance for the procurement, harvesting, preparation, storage, and other logistics related to the use of human cells for transplantation into the spinal cord, (d) to define more thoroughly the cell type(s) that would be most likely to have benefit and the conditions that affect their viability, migration, gene expressions, and proliferation after transplantation, (e) to determine the most optimal time after injury for transplantation, and (f) to clarify patient selection characteristics that might optimize success (i.e., complete vs incomplete injuries, spinal level involved, age of recipient).

Animals↗