The impact of treatment resistance on outcome and course of electroconvulsive therapy in major depressive disorder.

INTRODUCTION: Major depressive disorder (MDD) is a common psychiatric disorder. Despite several treatment options, a subgroup of patients will not respond to the commonly used antidepressant treatments and thus express treatment resistance (TRD). TRD can be quantified with the Dutch Measure for Treatment Resistance in Depression (DM-TRD). Electroconvulsive therapy (ECT) is an effective treatment for MDD, also in TRD. Yet, the position of ECT as "treatment-of-last-resort" may decrease the likelihood of beneficial outcome. Our aim was to investigate the association between treatment resistance and outcome and course of ECT. METHODS: We performed a retrospective, multicenter cohort study with 440 patients of which data was retrieved from patient records as collected in the Dutch ECT Cohort database. Linear and logistic regression models were used to explore the association between level of treatment resistance and outcome of ECT. Median split was used to explore the differences between high and low level of TRD and course of treatment. RESULTS: A higher DM-TRD score was associated with significantly smaller reduction of depression symptoms (R2 = 0.160; ß = -2.968; p < 0.001) and lower chance of response (OR = 0.821 [95 CI: 0.760-0.888]; ß = -0.197; p < 0.001). Low level TRD patients underwent fewer ECT sessions (mean 13 ± 6 SD vs. 16 ± 7 SD; p < 0.001) and fewer switches from right unilateral tot bifrontotemporal electrode placement (29% vs. 40%; p = 0.032). CONCLUSION: Reserving ECT as "treatment-of-last-resort" in the treatment algorithm for MDD seems questionable, because in our study lower level of treatment resistance predicted more beneficial ECT-outcome. Moreover, providing ECT in less treatment resistant patients showed fewer needed ECT-sessions and less switches to BL electrode placement, which may decrease the risk for cognitive side-effects.

[Proactive cognitive psychiatry while aging]. / Proactieve cognitieve psychiatrie bij het ouder worden.

BACKGROUND: COGNITIVE SYMPTOMS ARE COMMONLY REPORTED IN PATIENTS WITH UNIPOLAR OR BIPOLAR MOOD DISORDER. THE PREVALENCE OF COGNITIVE SYMPTOMS INCREASES WITH AGEING. THE PRESENCE AND EXTENT OF COGNITIVE SYMPTOMS HAS A DIRECT NEGATIVE IMPACT ON RECOVERY OF THE PSYCHIATRIC ILLNESS AND QUALITY OF LIFE.
AIM: IMPROVING OUTCOME OF OLDER PATIENTS WITH A UNIPOLAR OR BIPOLAR MOOD DISORDER.
METHOD: REVIEW OF AVAILABLE INTERVENTIONS TO IMPROVE COGNITIVE FUNCTIONING DIRECT OR INDIRECT.
RESULTS: STRATEGY TRAINING, TRAINING OF COGNITIVE FUNCTIONS AND PHYSICAL EXERCISE HAVE SHOWN TO BE EFFECTIVE TO IMPROVE COGNITIVE FUNCTIONING AND ITS POSSIBLE ADVANTAGES FOR PSYCHIATRIC POPULATIONS ARE CURRENTLY STUDIED IN THE NETHERLANDS. TREATMENT OF COMORBID INSOMNIA BY COGNITIVE BEHAVIORAL THERAPY MAY IMPROVE COGNITIVE FUNCTIONING INDIRECTLY BY DISCONTINUATION OF SLEEP MEDICATION, IMPROVEMENT OF SLEEP AND MOOD RELATED COGNITIVE SYMPTOMS.
CONCLUSION: A PROACTIVE APPROACH, INCLUDING SCREENING AND TREATMENT OF COGNITIVE SYMPTOMS BEFORE IMPAIRMENT OCCURS, IS WARRANTED TO OPTIMIZE OUTCOME OF THE AGEING PSYCHIATRIC PATIENT. TIJDSCHRIFT VOOR PSYCHIATRIE 63(2021)2, 120-124.

[ResPECT - a decade of Flemish-Dutch ECT research]. / ResPECT ­ een decennium Vlaams-Nederlands onderzoek naar elektroconvulsietherapie.

BACKGROUND: There is increasing clinical and scientific interest in electroconvulsive therapy (ECT). AIM: To provide an overview of the main research findings of the Flemish-Dutch research consortium ResPECT. METHOD: We report on our review of the relevant literature. RESULTS: Our studies confirm that ECT is one of the most efficient treatments for depression in later life and for depression with psychotic features. Older people with age-related brain pathology can respond well to ECT. It is still preferable to apply a standard pulse-width because this increases the efficacy of the treatment and minimises the cognitive impact. Even vulnerable older people can react favourably to ECT. CONCLUSION: Recent findings of the ResPECT consortium are providing new insights that are applicable in daily clinical practice. Research into mechanisms of action can also increase our understanding of the pathophysiology of severe depression.

Sex-specifics of ECT outcome.

OBJECTIVE: Electroconvulsive therapy (ECT) is the most effective treatment for patients with severe major depressive disorder (MDD). Given the known sex differences in MDD, improved knowledge may provide more sex-specific recommendations in clinical guidelines and improve outcome. In the present study we examine sex differences in ECT outcome and its predictors. METHODS: Clinical data from 20 independent sites participating in the Global ECT-MRI Research Collaboration (GEMRIC) were obtained for analysis, totaling 500 patients with MDD (58.6 % women) with a mean age of 54.8 years. Severity of depression before and after ECT was assessed with validated depression scales. Remission was defined as a HAM-D score of 7 points or below after ECT. Variables associated with remission were selected based on literature (i.e. depression severity at baseline, age, duration of index episode, and presence of psychotic symptoms). RESULTS: Remission rates of ECT were independent of sex, 48.0 % in women and 45.7 % in men (X2(1) = 0.2, p = 0.70). In the logistic regression analyses, a shorter index duration was identified as a sex-specific predictor for ECT outcome in women (X2(1) = 7.05, p = 0.01). The corresponding predictive margins did show overlapping confidence intervals for men and women. CONCLUSION: The evidence provided by our study suggests that ECT as a biological treatment for MDD is equally effective in women and men. A shorter duration of index episode was an additional sex- specific predictor for remission in women. Future research should establish whether the confidence intervals for the corresponding predictive margins are overlapping, as we find, or not.

Schwann cells for spinal cord repair.

The complex nature of spinal cord injury appears to demand a multifactorial repair strategy. One of the components that will likely be included is an implant that will fill the area of lost nervous tissue and provide a growth substrate for injured axons. Here we will discuss the role of Schwann cells (SCs) in cell-based, surgical repair strategies of the injured adult spinal cord. We will review key studies that showed that intraspinal SC grafts limit injury-induced tissue loss and promote axonal regeneration and myelination, and that this response can be improved by adding neurotrophic factors or anti-inflammatory agents. These results will be compared with several other approaches to the repair of the spinal cord. A general concern with repair strategies is the limited functional recovery, which is in large part due to the failure of axons to grow across the scar tissue at the distal graft-spinal cord interface. Consequently, new synaptic connections with spinal neurons involved in motor function are not formed. We will highlight repair approaches that did result in growth across the scar and discuss the necessity for more studies involving larger, clinically relevant types of injuries, addressing this specific issue. Finally, this review will reflect on the prospect of SCs for repair strategies in the clinic.

Distribution of corticospinal motor neurons in the postnatal rat: quantitative evidence for massive collateral elimination and modest cell death.

The postnatal development of rat corticospinal motor neurons (CSMN) was studied by retrograde tracing with cholera toxin B subunit (CTB) injected into the upper cervical dorsal spinal cord on the first postnatal day (P0), P3, P10, P20, and at adulthood. CTB-labeled neurons were visualized by immunocytochemistry and extensively quantified throughout the cortex. At P0, CSMN were found to an extent similar to that reported in P3 animals with other neuronal tracers, now permitting in vitro studies of neonatal CSMN. Between P0 and P3, the number of labeled neurons increased by 30% to a total maximum of approximately 185,000 in both cortices. The increase occurred throughout the cortex. At P10, the number of labeled CSMN had decreased to 60% of the number at P3. Fewer CSMN were evident particularly in the perirhinal cortex. Between P10 and P20, the number of CSMN decreased further to 52% of the maximal number at P3. This decrease occurred predominantly in the cingulate and parietal cortex. The number of labeled CSMN in rats injected at P0 and analyzed at P20 was 10% lower than the number in P0-injected littermates that were analyzed at P3, which suggests that only a small portion of the "disappearing" CSMN undergoes developmental neuronal death. Thus, the spinal projection of the remaining 38% is apparently eliminated between P3 and P20. Detailed quantitative analysis of the CSMN distribution demonstrated that neuronal death occurs predominantly in the perirhinal cortex. In contrast, axonal elimination of corticospinal projections occurred throughout the CSMN field, i.e., primarily in the frontal, occipital, and perirhinal cortex between P3-P10 and in the cingulate and parietal cortex between P10-P20.

Lumbar transplant of neurons genetically modified to secrete brain-derived neurotrophic factor attenuates allodynia and hyperalgesia after sciatic nerve constriction.

Chronic delivery of anti-nociceptive molecules by means of cell grafts near the pain processing centers of the spinal cord is a newly developing technique for the treatment of neuropathic pain. The rat neuronal cell line, RN33B, derived from E13 rat brainstem raphe and immortalized with the SV40 temperature-sensitive allele of large T antigen (tsTag), was transfected with rat brain-derived neurotrophic factor cDNA (BDNF), and the BDNF-synthesizing cell line, 33BDNF.4, was isolated. The 33BDNF.4 cells synthesized mature BDNF protein at permissive temperature (33 degrees C), when the cells were proliferating, and during differentiation at non-permissive temperature (39 degrees C) in vitro. The bio-active BDNF protein was also secreted by the cells during both growth conditions, as measured by ELISA analysis of BDNF content and secretion. The bio-activity of the BDNF in 33BDNF.4 cell conditioned media was assessed by neurite outgrowth from E15 dorsal root ganglion (DRG) cultures. A control cell line, 33V1, transfected with the vector alone, did not synthesize or secrete any significant BDNF at either growth condition. Both cell lines were used as grafts in a model of chronic neuropathic pain induced by unilateral chronic constriction injury (CCI) of the sciatic nerve. Pain-related behaviors, including cold and tactile allodynia and thermal and tactile hyperalgesia, were evaluated after CCI in the affected hindpaw. When 33BDNF.4 and 33V1 cells were transplanted in the lumbar subarachnoid space of the spinal cord 1 week after CCI, they survived greater than 7 weeks on the pia mater around the spinal cord and the 33BDNF.4 cells continued to synthesize BDNF in vivo. Furthermore, the tactile and cold allodynia and tactile and thermal hyperalgesia induced by CCI was significantly reduced during the 2-7 week period after grafts of 33BDNF.4 cells. The maximal effect on chronic pain behaviors with the BDNF grafts occurred 2-3 weeks after transplant and the anti-nociceptive effects of the BDNF cell grafts was permanent. Transplants of the control 33V1 cells had no effect on the allodynia and hyperalgesia induced by CCI and these cells did not synthesize BDNF in vivo. These data suggest that a chronically applied, low local dose of BDNF supplied by transplanted cells near the spinal dorsal horn was able to reverse the development of chronic neuropathic pain following CCI. The use of neural cell lines that are able to deliver anti-nociceptive molecules, such as BDNF, in a model of chronic pain offers a novel approach to pain management and such 'biologic minipumps' can be developed for safe use in humans.

Adeno-associated viral vector-mediated neurotrophin gene transfer in the injured adult rat spinal cord improves hind-limb function.

To foster axonal growth from a Schwann cell bridge into the caudal spinal cord, spinal cells caudal to the implant were transduced with adeno-associated viral (AAV) vectors encoding for brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (AAV-NT-3). Control rats received AAV vectors encoding for green fluorescent protein or saline. AAV-BDNF- and AAV-NT-3-transduced 293 human kidney cells produced and secreted BDNF or NT-3, respectively, in vitro. The secreted neurotrophins were biologically active; they both promoted outgrowth of sensory neurites in vitro. In vivo, transgene expression was observed predominantly in neurons for at least 16 weeks after injection. Compared with controls, a modest though significant improvement in hind-limb function was found in rats that received AAV-BDNF and AAV-NT-3. Retrograde tracing demonstrated that twice as many neurons with processes extending toward the Schwann cell graft were present in the second lumbar cord segment of AAV-BDNF- and AAV-NT-3-injected animals compared with controls. We found no evidence, however, for growth of regenerated axons from the Schwann cell implant into the caudal cord. Our results suggest that AAV vector-mediated overexpression of BDNF and NT-3 in the cord caudal to a Schwann cell bridge modified the local lumbar axonal circuitry, which was beneficial for locomotor function.

Neutralizing antibodies against neurite growth inhibitor NI-35/250 do not promote regeneration of sensory axons in the adult rat spinal cord.

Neutralization of the myelin-associated neurite growth inhibitors NI-35 and NI-250 by IN-1 antibodies can promote axonal regeneration of several types of central nervous neurons. Here, we investigated in adult rats whether IN-1 can promote regeneration of ascending sensory axons across a peripheral nerve bridge back into the spinal cord. IN-1 was administered by hybridoma cells injected in the cerebral cortex or thoracic cord, its presence confirmed in tissue sections and cerebrospinal fluid, and its effectiveness demonstrated in co-cultures of oligodendrocytes and sensory neurons. With a two week infusion of control vehicle into the dorsal spinal cord 3 mm rostral to the nerve graft, only 3+/-2% of the anterogradely labeled sensory fibers present at the rostral end of the nerve graft had grown up to 0.5 mm, but not farther into the spinal cord. A similar limited extent of regeneration was seen with IN-1 or with infusion of Dantrolene, an inhibitor of NI-35/250 activity in vitro. With infusion of nerve growth factor rostral to the nerve graft, 40% of the fibers at the rostral end of the graft were found at 0.5 mm, 34% at 1 mm, 24% at 2 mm and 14% at 3 mm (the infusion site) into the spinal cord. Treatment with IN-l antibodies did not enhance the growth-promoting effects of nerve growth factor. We suggest that the neurite growth inhibitors NI-35 or NI-250 do not play a major inhibitory role in the regeneration of the ascending sensory fibers across a nerve bridge and back into the spinal cord of the adult rat.

Axonal regeneration into Schwann cell grafts within resorbable poly(alpha-hydroxyacid) guidance channels in the adult rat spinal cord.

Axonal growth and myelination in a SC graft contained in a resorbable tubular scaffold made of poly(D,L-lactic acid) (PLA50) or high molecular weight poly(L-lactic acid) mixed with 10% poly(L-lactic acid) oligomers (PLA(100/10)) were studied for up to 4 months after implantation in the completely transected adult rat thoracic spinal cord. The PLA50 tubes collapsed soon after implantation and, consequently, compressed the graft inside, leading to only occasional thin cables with SCs and a low number of myelinated axons: 17 +/- 6 at 1 and 158 +/- 11 at 2 months post-grafting. The cable contained 32 +/- 23 blood vessels at 2 weeks, 55 +/- 33 at 1 month and 46 +/- 30 at 2 months after implantation. PLA(100/10) tubes, on the other hand, were found to break up into large pieces, which compressed and sometimes protruded into the tissue cable inside. At all time points studied, however, cables contained SCs and were well vascularized with 414 +/- 47 blood vessels at 2 weeks, 437 +/- 139 at 1, 609 +/- 134 at 2 and 396 +/- 95 at 4 months post-grafting. The number of myelinated axons was 712 +/- 509 at 1 month, 1819 +/- 837 at 2 months and 609 +/- 132 at 4 months post implantation. These results demonstrated that fiber growth and myelination into a SC graft contained in a resorbable PLA(100/10) tube increases over the first 2 months post-implantation but decreases thereafter. Changes in geometry of both types of polymer tubes were detrimental to axonal regeneration. Future research should explore the use of polymers that better retain the appropriate mechanical, geometrical and permeability properties over time.

CNTF promotes the survival of neonatal rat corticospinal neurons in vitro.

Corticospinal neurons were identified in cell cultures of neonatal rat cortex by immunostaining of cholera toxin B subunit (CTB), retrogradely transported from the cervical part of the spinal cord. The CTB-immunoreactive neurons were larger than the neurons in the overall (unstained) neuronal population and represented a small fraction of it (average of 0.3%) after 6 hours in vitro. The number of both total and CTB-labeled neurons declined progressively with time in culture. The neuronal death was, however, markedly faster in the CTB-labeled neuronal population than in the overall neuronal population. Ciliary neurotrophic factor (CNTF) promoted the survival of CTB-positive corticospinal neurons in a dose-dependent manner; with CNTF, the death rate of the CTB-labeled neurons became identical to that of the overall population.

Neurotrophins promote regeneration of sensory axons in the adult rat spinal cord.

We have investigated the effects of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) on the intraspinal regeneration of anterogradely labeled axotomized ascending primary sensory fibers in the adult rat. These fibers were allowed to grow across a predegenerated peripheral nerve graft and back into the thoracic spinal cord. In control animals that had been infused with vehicle for two weeks into the dorsal column, 3 mm rostral to the nerve graft, essentially no fibers had extended from the nerve graft back into the spinal cord. The number of sensory fibers in the rostral end of the nerve graft was not significantly different between control and neurotrophin-infused animals. With infusion of NGF, 37+/-2% of the fibers at the rostral end of the graft had grown up to 0.5 mm into the dorsal column white matter, 30+/-2% up to 1 mm, 19+/-3% up to 2 mm and 8+/-2% up to 3 mm, i.e., the infusion site. With infusion of NT-3, sensory fiber outgrowth was similar to that seen with NGF, but with BDNF fewer fibers reached farther distances into the cord. Infusion of a mixture of all three neurotrophins did not increase the number of regenerating sensory fibers above that seen after infusion of the individual neurotrophins. These findings suggest that injured ascending sensory axons are responsive to all three neurotrophins and confirm our previous findings that neurotrophic factors can promote regeneration in the adult central nervous system.

Microtubule-associated protein 1a is involved in the early development of the rat spinal cord.

The expression of microtubule-associated protein 1a (MAP1a) in the developing rat spinal cord was studied using the monoclonal antibody BW6. Immunoblots of microtubule preparations revealed the presence of MAP1a in spinal cord tissue of rats aged embryonal day 16 and postnatal day 0. The spinal cord matrix layer, between embryonal days 12-17, displayed a pattern of MAP1a-positive processes, horizontally oriented in between the membrane limitans interna and externa. The mantle layer stained intensely for MAP1a between embryonal day 12 and postnatal day 2. MAP1a was found in neuronal cell bodies, axons and dendrites, located mainly in the ventral and intermediate mantle layer. In the marginal layer, MAP1a-positive axons could be observed between embryonal days 14-18. During further development, the intensity of the MAP1a staining in the spinal columns gradually decreased. These expression patterns indicate an involvement of MAP1a in the proliferation and differentiation of neuroblasts, and the maturation of the long spinal fiber systems, i.e. early events in spinal cord development

Potential regulation by trophic factors of low-affinity NGF receptors in spinal motor neurons.

Developing spinal motor neurons (SMN) express low-affinity nerve growth factor receptors (LNGFR) but not high-affinity transducing NGF receptors. Moreover, SMN are not supported by NGF in vitro. In the normal adult rat most SMN are not LNGFR immunoreactive (LNGFR-IR), but they transiently reexpress LNGFR (though not the high-affinity receptor) after peripheral nerve injury. With a cut lesion of the sciatic nerve (when only a neuroma forms), the number of LNGFR-IR SMN at L4-L6 rapidly increases to a maximum between day 1 and 7 and returns to baseline levels by day 30. After a crush lesion (accompanied by regeneration to the muscle), LNGFR-IR SMN appear in about the same numbers, but they start to disappear 1 week later. We speculate that the similar appearance and differential decline of LNGFR-IR seen after the two types of lesions are regulated by the availability of a common signal such as ciliary neurotrophic factor. The adult SMN model provides a good opportunity to investigate the reexpression of LNGFR after peripheral nerve injury, and more generally, the unknown role and regulation of LNGFR.

Acetylcholinesterase in the developing rat spinal cord: an enzyme histochemical study.

A descriptive enzyme histochemical study on the expression of acetylcholinesterase (AChE) in the developing rat spinal cord is presented. Between E11-E16, AChE was found to be associated with premitotic neurons of the ventral matrix layer, which indicated an involvement in the proliferation of the spinal cord motor neurons. From E12 on, AChE was abundantly present in the motor neurons of the ventral mantle layer, and in their fibres. This early expression suggested a function of AChE in the development of the motor neurons, rather than an active role in cholinergic transmission. The intermediolateral, the intermediomedial cell column and the region between these cell groups, were found to be positive for AChE. Cells of the adult intermediolateral cell column also expressed AChE. AChE, therefore, apparently plays a role in the development as well as in the functioning of the rat autonomic system. In the lateral funiculus, cells of the lateral spinal nucleus expressed AChE. After P8, AChE was expressed in the substantia gelatinosa. The enzyme may be associated with the fibre terminals of the primary afferents. AChE was found to be temporary expressed in the developing dorsal funiculus, which suggested a function of the enzyme in fibre growth and path-finding. At E12, AChE was located in the ventral aspect of the dorsal root ganglion. Later on, AChE positive cells were found throughout the ganglion.

Morphological and functional properties of rat dorsal root ganglion cells cultured in a chemically defined medium.

A culture procedure for dorsal root ganglion (DRG) cells is presented using a completely defined culture medium without antibiotics, in combination with mechanical dissociation procedures. This culture procedure allows all dorsal root ganglion cell types to be cocultured for periods of at least 106 days. Some of the dorsal root ganglion neurons, which could be identified by their neurofilaments and the presence of fluoride resistant acid phosphatase, regained their original T-cell appearance within two weeks. After one month in culture ganglion-like reaggregates appeared. Schwann cells, satellite cells and fibroblasts were identified using morphological criteria. All neurons tested maintained excitability during, at least, the first 35 days in culture, since in all cases action potentials could be evoked by current pulses. The method has proved to be useful in the study of morphological, cytochemical and electrophysiological aspects of dorsal root ganglion cell differentiation in vitro.

Immunocytochemical localization of neurofilaments in the fibre systems of the developing rat spinal cord white matter.

The appearance and localization of the protein subunits of neurofilaments in the ascending and descending fibre systems of the developing rat spinal cord white matter were studied. The monoclonal antibody NF-90 (specific for the phosphorylated NF-L, NF-M and NF-H subunits) was used as neurofilament marker in fresh cryostat and Bouin fixed paraffin sections. The results were compared with Nissl and Bodian stained sections. Within the white matter, phosphorylated neurofilament proteins were expressed with regional variations. At embryonal day 12 (E12), the first positive fibres were found in the lateral funiculus. During further development, the peripheral region of the lateral funiculus showed an intense neurofilament staining, due to the presence of a higher number of fibres. From postnatal day 12 (P12) on, an increased amount of neurofilaments was found in the region close to the periphery, probably due to the presence of large calibre fibres. The dorsolateral part of the lateral funiculus filled in with fibres after birth, which indicated the extended development of the rubrospinal tract. At E13, positive fibres were present in the ventral commissure and the ventral funiculus. At E14, an increased amount of neurofilaments was detected in the periphery of the ventral funiculus. At maturity, an intense staining in the subsurface region could be found, due to the presence of large calibre fibres of the fasciculus longitudinalis medialis. At E13, the first neurofilament positive fibres were present in the dorsal funiculus. At this day, a concentration of fibres was found in the dorsal part of the dorsal root bifurcation zone and three days later, more fibres were detected in the medial part of the dorsal funiculus. At E18, a higher number of fibres was present in the dorsal region of the fasciculus gracilis. The mature fasciculus cuneatus showed an intense neurofilament staining, which was mainly present in large calibre fibres. The ventral part of the dorsal funiculus filled in with neurofilament positive fibres after birth. This indicated the relative late arrival of the corticospinal tract.

Combination therapies.

Spinal cord injury (SCI) has multiple consequences, ranging from molecular imbalances to glial scar formation to functional impairments. It is logical to think that a combination of single treatments implemented in the right order and at the right time will be required to repair the spinal cord. However, the single treatments that compose the combination therapy will need to be chosen with caution as many have multiple outcomes that may or may not be synergistic. Single treatments may also elicit unwanted side-effects and/or effects that would decrease the repair potential of other components and/or the entire combination therapy. In this chapter a number of single treatments are discussed with respect to their multiplicity of action. These include strategies to boost growth and survival (such as neurotrophins and cyclic AMP) and strategies to reduce inhibitory factors (such as antimyelin-associated growth inhibitors and digestion of glial scar-associated inhibitors). We also present an overview of combination therapies that have successfully or unsuccessfully been tested in the laboratory using animal models. To effectively design a combination therapy a number of considerations need to be made such as the nature and timing of the treatments and the method for delivery. This chapter discusses these issues as well as considerations related to chronic SCI and the logistics of bringing combination therapies to the clinic.

Early passage bone marrow stromal cells express genes involved in nervous system development supporting their relevance for neural repair.

PURPOSE: The assessment of the capacity of bone marrow stromal cells (BMSC) to repair the nervous system using gene expression profiling. The evaluation of effects of long-term culturing on the gene expression profile of BMSC. METHODS: Fourty four k whole genome rat microarrays were used to study gene expression of cultured BMSC at passage (P)3 and to compare expression profiles between P3 and P14 BMSC. Quantitative PCR was employed to validate the microarray results. RESULTS: P3 BMSC expressed genes involved in neural developmental events such as glial differentiation, neuron proliferation, and neurite formation. They also express genes encoding for growth factors and for proteins involved in growth factor signaling. A total of 6687 genes were co-expressed in P3 and P14 BMSC. Of these co-expressed genes, 3% (202 genes) was differentially expressed with 159 genes higher in P3 BMSC and 43 genes higher in P14 BMSC. The gene expression patterns were independently validated using quantitative PCR. Functional data mining by Gene Ontology (GO)-analysis revealed that 85/159 and 22/43 genes were annotated in the GO database. In P3 BMSC, 53 GO-classes were overrepresented with several involved in organ development, cell proliferation, and neural repair. In P14 BMSC, three GO-classes were overrepresented with one involved in organ development. CONCLUSIONS: Our gene profiling results suggested a decreased plasticity and repair aptitude of long-term cultured BMSC. Our data indicated the use of early passage BMSC for neural repair approaches.