Afferent and efferent connections of striatal grafts implanted into the ibotenic acid lesioned neostriatum in adult rats

Summary The afferent and efferent connections of grafts of fetal caudate-putamen, implanted into the ibotenic acid (IA)-lesioned striatum of adult rats, have been studied with wheat germ agglutinin conjugated horseradish peroxidase (WGA-HRP) as a combined retrograde and anterograde tracer, and with aldehyde fluorescence histochemistry for the visualisation of dopamine-containing nigrostriatal afferents from the host. The WGA-HRP was deposited in crystalline form (within a capillary tip) either into the depth of the graft tissue, or into the IA lesioned host striatum as a control. Labelling was only evaluated in specimens where the WGA-HRP deposit was entirely confined within the graft. Retrogradely labelled neurons were most consistently found in the ipsilateral host substantia nigra and the spared portions of the host CP, and in one case also in the midline and intralaminar thalamic nuclei normally projecting to the striatum. Some neurons, although weakly labelled, occurred in the deep layers of the frontal cortex in all grafted rats. Signs of anterograde WGA-HRP labelling in the host were found in one of the five animals in the ipsilateral globus pallidus and substantia nigra, pars reticulata. Fluorescence histochemistry revealed extensive ingrowth of dopamine-containing fibres from the host striatum into the grafted striatal tissue. The ingrowing fibres formed distinct and partly interconnected patches, most prominently in the peripheral regions of the grafts. The results provide evidence that intrastriatal grafts of fetal striatal tissue receive extensive dopaminergic afferents from the host substantia nigra, and that they may be capable of establishing connections also with thalamus, neocortex and globus pallidus of the host, as well as with the spared portions of the host caudate-putamen. The afferent connections from the thalamus and neocortex were notably more variable and sparse. However, since the control WGA-HRP deposits (into the lesioned host striatum) labelled the cortical and thalamic afferent neurons only poorly, it appears that the cortico-striatal and thalamo-striatal afferents (in contrast to the nigro-striatal ones) had undergone substantial degenerative changes (atrophy and/or cell death) in the long-term (6–11 months) IA-lesioned rats. The sparse thalamic and cortical afferent connections to the grafts may thus reflect an inability of the grafted striatal tissue to prevent the course of degenerative changes in these striatal input systems.     

Anatomical and behavioral comparison of unilateral dopamine-rich grafts implanted into the striatum of neonatal and adult rats.

The anatomical and functional characteristics of dopamine neuron-rich grafts implanted into rat pups were compared with those of identical grafts implanted into adult hosts. The host nigrostriatal dopaminergic pathway was unilaterally destroyed by an intrahypothalamic injection of 6-hydroxydopamine. This was followed five days later by the implantation of a cellular suspension obtained from rat embryonic mesencephali. Identical operations were carried out on adult and infant (PD3) rats. The survival rate of implanted tyrosine hydroxylase-positive cells was lower in the neonates. On the other hand, in the neonate hosts, surviving immunoreactive cells migrated extensively throughout the host striatum coursing preferentially below the corpus callosum and towards the subependymal zone. The structural integrity of the host parenchyma was well maintained after the neonatal implantation, in contrast to that observed in the adults. Despite a difference in the cell survival rate, there was no major difference in reinnervation density between the two types of host. The functional capacities of the implants were evaluated by measuring the rotational responses of the animals to dopaminergic agonists. The implants compensated the lesion-induced contralateral rotational response to the mixed agonist apomorphine and the D1 agonist SCH-38393 in both neonates and adults. However, the response to the D2 agonist LY-171555 was not significantly attenuated by the implant. The ipsilateral rotational response to amphetamine observed in the lesioned animals was also compensated and even reversed by the graft. It is concluded that with respect to rotational behavior, similar functional benefits were observed following adult stage or neonatal implantation, despite differences in their anatomical development.     

Intracerebral xenografts of dopamine neurons: the role of immunosuppression and the blood-brain barrier

Summary Fetal mesencephalic mouse tissue, rich in dopamine neurons, was xenografted as a dissociated cell suspension into the striatum of rats with unilateral 6-hydroxydopamine induced lesions of the mesostriatal pathway. The rats were either assigned to a 10-day, 21-day or 42-day Cyclosporin A (CyA) immunosuppression scheme, or given no immunosuppression. The functional effects of the grafts were followed over 6 months by monitoring changes in the recipient rats' amphetamine-induced turning behaviour. Without immunosuppression no grafts were functional at the end of the experiment. In the 10-, 21-and 42-day CyA treatment groups there was a significant reduction of rotational asymmetry at some timepoint following grafting in 26 of the 33 rats. However, by 6 months only 8 grafts remained functional suggesting that in several rats an immunological rejection took place following the termination of immunosuppression. This was supported by catecholamine histofluorescence analysis which revealed evidence of surviving grafts only in the few rats which had shown sustained functional graft effects at 6 months after grafting. In animals in which the grafts had undergone rejection, there was scarlike tissue in the striatum which appeared more extensive in rats that had lost their grafts after several weeks compared to rats in which the grafts were rejected at an early time-point. In a subgroup of the grafted animals the humoral antibody response against major transplantation antigens present on the grafted cells was investigated. All the studied rats were found to be immunized against the grafted mouse tissue following the intrastriatal implantation. This occurred irrespective of prior immunosuppressive treatment. In a parallel group of rats, the leakage of the blood-brain barrier was studied following intrastriatal implantation of a syngeneic fetal neural cell suspension. Evans Blue was infused into rats 3–12 days following transplantation surgery. At the early time-points there was a marked barrier leakage at the implantation site. This subsided with time such that there was minor leakage after 7–8 days and no leakage after 12 days. In summary, the results indicate the CyA is effective in promoting survival of intracerebral xenografts of fetal neural tissue, but that cessation of immunosuppressive treatment in most cases results in rejection of the grafted tissue. Temporary CyA treatment, even exceeding the time it takes for the blood-brain barrier to reform after transplantation surgery, is thus not sufficient to reliably support long term survival of xenografted dopamine neurons.     

Histological signs of immune reactions against allogeneic solid fetal neural grafts in the mouse cerebellum depend on the MHC locus

Summary Using an immunocytochemical method, we examined the immunological responses of adult mice to intracerebellar syngeneic and allogeneic fetal mouse brainstem transplants (embryonic days 12–14). Syngeneic grafts and major histocompatibility complex (MHC)-compatible and non-MHC-incompatible allogeneic grafts survived well, showing no histological signs of rejection even 6 months after transplantation, and with no expression of MHC antigens being observed in any of the grafts. However, most cases of both MHC- and non-MHC-incompatible allografts showed rejection responses, such as marked neovascularization, cellular infiltration and necrosis, two weeks to one month after transplantation. In animals showing rejection, Class I MHC antigens were found on grafted neuronal tissue. An increased number of reactive astrocytes was also observed in the grafts. High levels of Class I antigen expression and prominent gliosis correlated with vigorous cellular infiltration. A quantitative analysis of T cell subsets in the animals showing rejection revealed that the L3T4/Lyt-2 ratio was 1.02±0.21 (mean ± S.D.), indicating that helper/inducer and cytotoxic/suppressor T cells appeared equally in the rejection of MHC- and non-MHC-incompatible allografts. We consider that in these experiments, the brain was not completely an immunologically privileged site, and that MHC- and non-MHC-incompatible intraparenchymal neural transplants were not shielded from host immune surveillance.     

Amelioration of the behavioral phenotype in weaver mutant mice through bilateral intrastriatal grafting of fetal dopamine cells

Weaver mutant mice lose more than twothirds of their nigral dopamine neurons. Behaviorally, weaver homozygotes display tremor, gait instability, and toppling over to the sides after a few steps. The recovery of functional responses was determined in a battery of behavioral tests in weaver mutants after bilateral transplantation of mesencephalic cell suspensions (prepared from wild-type mice) to the striatum. Equilibrium was tested by the time mice were able to stay on a suspended balance rod before falling off. Locomotor coordination was measured by the number of times mice toppled over to the sides as they moved about in an open-field matrix. Locomotor activity was quantified by the number of square crossings in an open-field matrix. Grafted weaver mutants performed significantly better than non-grafted mutant mice in all of these three tasks. The findings clearly demonstrate that bilateral transplants of foetal DA cells enhance motor performance in the weaver model of chronic nigrostriatal DA deficiency.     

Time-course of recovery of dopamine neuron activity during reinnervation of the denervated striatum by fetal mesencephalic grafts as assessed by in vivo voltammetry

Summary In vivo voltammetry was used to monitor dopamine (DA) neuron activity during the course of reinnervation of the initially denervated caudateputamen by grafted mesencephalic neurons. Fetal DA neurons were implanted as a cell suspension into the depth of the caudate-putamen in adult 6-hydroxydopamine-lesioned recipient rats. Recordings were performed over a period of 2.5–4 months, starting within a week after transplantation, using chronically implanted surface-treated multifiber carbon electrodes. The voltammetric method used in this study has generated considerable discussion centred on the ability of the multifiber electrodes to measure DA alone in vivo, but the results of previous studies have led to the conclusion that changes in the voltammetric signal most probably reflect dopaminergic terminal activity. It seems therefore possible to follow the time-course of changes in the voltammetric signal amplitude during the process of dopaminergic reinnervation of the host striatum from the grafts. A 6-hydroxydopamine lesion of the mesostriatal dopamine pathway caused a substantial (> 80%) reduction of the voltammetric signal within 8–10 days, and the low residual signal remained essentially unchanged for time periods up to at least 5 months in the non-grafted control rats. In 7 of 11 rats with DA-rich grafts there was a recovery of the signal amplitude to levels within, or close to, the range recorded from the striatum of normal intact rats. The increase was observed 6–8 weeks after grafting in the rats which had received the largest transplants, and at about 13–14 weeks after grafting in the rats which had received the smallest ones. The recovery of the signal amplitude, from baseline to maximal response, was quite rapid and typically developed between two or three recording sessions, i.e. over a period of one to two weeks. In contrast to the intact striatum, the recovered signal in the graft-reinnervated striata showed a progressive decline within one hour of sampling time at high sampling frequencies (1 per min to 1 per 3 min). Grafted striata also showed a larger response to systemically administered amphetamine than did intact striata. Since the changes in the voltammetric signal recorded with the multifiber electrode mainly reflect dopaminergic terminal activity, the results provide evidence that the intrastriatal DA-rich grafts are spontaneously active, and that the grafted DA neurons can restore DA neuro-transmission in the reinnervated part of the host caudate-putamen to levels which are within the normal range. From the time-course of changes in the voltammetric signal it can be estimated that the outgrowing DA fibers, after an initial maturation period, expand from the graft into the host striatum at a maximum rate of about 0.1 mm per week, and that the advancing front of graft-derived fibers may be capable of saturating the area around the electrode tip with new terminals within a time period of about 1–2 weeks. The characteristics of the signal seem compatible with the view that the activity of the individual grafted DA neurons is greater than that of the mesostriatal DA neurons in situ.     

异基因骨髓移植小鼠免疫功能缺损机制的探讨

异基因骨髓移植(Allogeneic Bone Marrow Transplantation,ABMT)后,受体的免疫功能长期缺损,是患者术后极易感染死亡的重要原因之一.本文对ABMT小鼠(C57BL/6→BALB/c)免疫功能缺损的机制进行了探讨,发现ABMT小鼠IL-2产生明显受损;其脾细胞与(C57BL/6小鼠脾细胞一起过继转移到致死量照射的BALB/C小鼠体内,能抑制移植物抗宿主病(GVHD)的发生.去除其脾T细胞后,这种抑制作用丧失,ABMT小鼠脾细胞上清中发现一种非特异的抑制因子,能抑制正常小鼠脾细胞产生混合淋巴细胞反应的能力;能抑制正常小鼠的脾细胞产生IL-2;抑制正常小鼠脾细胞毒T淋巴细胞(CTL)的杀伤活性.用抗Thy-1.2单抗和补体去除ABMT小鼠脾T细胞后,其脾细胞培养上(?)的上述抑制活性丧失.这说明ABMT小鼠脾T(?)细胞活性增强是其免疫功能缺损的重要原因之一,它通过释放非特异的抑制因子执行其免疫抑制功能.     

Development of fetal hypothalamic magnocellular neurosecretory neurons transplanted into the third ventricle of the adult rat brain

Department of Biology, N. I. Pirogov Second Moscow Medical Institute. Department of Biology, Khar'kov Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Smirnov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 105, No. 2, pp. 224–227, February, 1988.     

Survival and function of aggregate cultures of rat fetal dopamine neurons grafted in a rat model of Parkinson's disease

Summary The ability to maintain tissue in culture prior to grafting would greatly facilitate the widespread application of graft therapy to neurological diseases such as Parkinson's disease. However, neurons cultured on planar substrata can be easily damaged when they are removed from the substrata and redissociated for use in grafting procedures. To overcome this limitation we utilized aggregate tissue culture methods, which allowed dopamine (DA)-rich neuronal tissue to be grafted directly following culture, without an additional redissociation. Fetal rat dopamine-neuron-containing ventral mesencephalon was cultured for 9 days in rotating flasks. The cells formed many small spheres (280 m mean diameter), each estimated to contain about 10000 cells. Forty such aggregate spheres were injected via a 22G needle into the DA-denervated striata of host Parkinsonian rats. A significant reduction of amphetamine-induced rotation was seen onward from 6 weeks post-transplantation, with a complete reversal of rotational asymmetry by 15 weeks post-transplantation. Well placed, surviving grafts were found in all behaviorally compensated rats (N = 6). Grafts contained an average of 517 tyrosine hydroxylase (TH)-positive neurons, as well as TH-positive fibers seen extending into the host striatum. These results suggest that aggregate culture methods are a promising means to maintain and deliver tissue for transplant therapy.     

Human fetal dopamine neurons grafted in a rat model of Parkinson's disease: immunological aspects,spontaneous and drug-induced behaviour,and dopamine release

Summary We have used a rat model of Parkinson's disease (PD) to address issues of importance for a future clinical application of dopamine (DA) neuron grafting in patients with PD. Human mesencephalic DA neurons, obtained from 6.5–8 week old fetuses, were found to survive intracerebral cell suspension xenografting to the striatum of rats immunosup-pressed with Cyclosporin A. The grafts produced an extensive new DA-containing terminal network in the previously denervated caudate-putamen, and they normalized amphetamine-induced, apomorphine-induced and spontaneous motor asymmetry in rats with unilateral lesions of the mesostriatal DA pathway. Grafts from an 11.5-week old donor exhibited a lower survival rate and smaller functional effects. As assessed with the intracerebral dialysis technique the grafted DA neurons were found to restore spontaneous DA release in the reinnervated host striatum to normal levels. The neurons responded with large increases in extracellular striatal DA levels after the intrastriatal administration of the DA-releasing agent d-amphetamine and the DA-reuptake blocker nomifensine, although not to the same extent as seen in striata with an intact mesostriatal DA system. DA fiber outgrowth from the grafts was dependent on the localization of the graft tissue. Thus, grafts located within the striatum gave rise to an extensive axonal network throughout the whole host striatum, whereas grafted DA neurons localized in the neocortex had their outgrowing fibers confined within the grafts themselves. In contrast to the good graft survival and behavioural effects obtained in immunosuppressed rats, there was no survival, or behavioural effects, of human DA neurons implanted in rats that did not receive immunosuppression. In addition, we found that all the graft recipients were immunized, having formed antibodies against antigens present on human T-cells. This supports the notion that the human neurons grafted to the non-immunosuppressed rats underwent immunological rejection. Based on an estimation of the survival rate and extent of fiber outgrowth from the grafted human fetal DA neurons, we suggest that DA neurons that can be obtained from one fetus may be sufficient to restore significant DA neurotransmission unilaterally, in one putamen, in an immunosuppressed PD patient.The results of this study were presented at the Schmitt Neurological Sciences Symposium on Transplantation into the Mammalian CNS, Rochester, NY, USA, June 30, 1987     

Combined grafts of the ventral tegmental area and nucleus accumbens in oculo. Histochemical and electrophysiological characterization

Summary Dissection techniques and optimal donor stages have been established for constructing an isolated intraocular model of the ventral tegmental area (VTA)-accumbens system using intraocular sequential grafting. Single grafts including accumbens and VTA respectively survived and developed many organotypic features when taken from 15–17 day fetuses. Falck-Hillarp fluorescence histochemistry showed dopamine neurons and terminals in single VTA grafts, no or almost no catecholamine fibers in single accumbens grafts, and a well-developed VTA-accumbens dopamine pathway in combined grafts where cell bodies in the VTA part provided the accumbens part with a rich terminal network. A similar distribution was found using immunohistochemistry with antibodies directed against tyrosine hydroxylase. CCK-like immunoreactivity had a distribution that mimicked that of the catecholamine-containing system. Enkephaline-like immunoreactivity was found both in single VTA and in single accumbens pieces as well as in both parts of the double grafts. Cells with long-duration action potentials typical of dopamine neurons discharged at approximately 8 Hz in single VTA grafts and below 1 Hz in the VTA part of VTA-accumbens double grafts. Cells in the accumbens portion of double grafts had shorter action potential durations and fired at 10–20 Hz. Haloperidol increased discharge frequency in VTA neurons with long action potential durations while apomorphine reduced discharge markedly. Antidromic activation of putative dopamine neurons in the VTA part was obtained by electrical stimulation of the accumbens part. The indirect dopamine agonist + 3-methyl-phencyclidine slowed firing rates of neurons in the accumbens part of double grafts. Taken together, the histochemical and the electrophysiological data show that the intraocular VTA-accumbens system retains several of its normal structural and functional characteristics. It is proposed that the isolated VTA-accumbens projection can be used as a model to study the cellular mechanism of action of stimulant and opiate drugs of abuse.     

六羟多巴胺对成年小鼠黑质-纹状体系统多巴胺能神经元及其行为学的影响

目的评估中脑黑质损伤后内源性神经前体细胞(NPCs)的增殖情况及其对黑质-纹状体系统损伤后恢复的促进作用。方法向成年小鼠的一侧黑质(SN)注射六羟多巴胺(6-OHDA),损伤后3~35 d运用免疫荧光染色等方法,研究小鼠来自侧脑室、第三脑室、中脑水管周围及中脑部分NPCs的增殖,探索黑质中新生细胞的增殖及其向成熟神经元、多巴胺能神经元分化的情况,最后通过旷场和转棒实验检测小鼠行为学的变化(每组n=4~6)。结果黑质内注射6-OHDA引起的多巴胺能神经元损失可以明显增加第三脑室和中脑水管周围来自室管膜下区的NPCs的数目,以6-OHDA注射后的第7天最为明显,且6-OHDA注射后第21天黑质内新生细胞和新生多巴胺能神经元的数目增加达到高峰,这些变化可能导致了受损的黑质-纹状体系统及小鼠行为学表现有部分恢复。结论促进内源性NPCs的增殖和分化将成为治疗帕金森病的理想手段。     

Increased proportion of acetylcholinesterase-rich zones and improved morphological integration in host striatum of fetal grafts derived from the lateral but not the medial ganglionic eminence

Fetal striatal grafts are found to have a modular organization revealed by acetylcholinesterase (AChE) histochemistry. The AChE-rich zones represent the only portions of these grafts that are anatomically and functionally integrated into the host brain. In this study, the medial and lateral ganglionic eminences (MGEs and LGEs) were selectively dissected from the basal telencephalon of embryonic-day-14 (E14) rat fetuses to compare their relative contributions to the AChE-rich fraction of intrastriatal grafts. Separate cell suspensions prepared from either eminence were stereotaxically implanted into excitotoxically lesioned neostriatum of adult rats. Eight weeks after transplantation, grafts of the MGE were compared with those of the LGE with respect to the proportion of AChE-rich zones, graft size, graft morphology, and afferent dopaminergic innervation as revealed by tyrosine hydroxylase (TH) immunostaining. The mean AChE-rich fraction in LGE grafts (87%±4%) was markedly greater than the AChE-rich fraction in MGE grafts (25%±10%). The LGE grafts were also morphologically better incorporated into the lesioned host striatum, partially reconstituting the striatal morphology. There was no statistically significant difference in graft size between the two groups. The AChE-rich LGE grafts were TH immunoreactive, whereas the AChE-poor MGE grafts were not. We conclude that grafts derived exclusively from the fetal LGE reconstitute the striatal morphology and consist almost entirely of AChE-rich zones.     

Survival of neural progenitor cells from the subventricular zone of the adult rat after transplantation into the host spinal cord of the same strain of adult rat

The subventricular zone (SVZ) of the lateral ventricle of the mammalian forebrain is the major site in which neural progenitor cells (NPC) persist in the adult brain. The NPC are located beneath ventricular ependymal cells and have the capacity to self-renew and continuously produce neurons and glial cells. We have shown previously that neurospheres can be obtained from the brain of deceased adult rats and that neurosphere cells survive after transplantation into the spinal cord. In the present study, we investigated whether fresh NPC from living adult rats can survive and be integrated into host tissues after transplantation into the adult rat spinal cord of the same strain. We used rats expressing transgenic green fluorescent protein (GFP) as a donor to identify the transplanted NPCs. The SVZ tissues were obtained from the striatal wall of the lateral ventricle of adult GFP-rats and were grafted into lesions of the spinal cord at the cervical level. Two to 3 weeks after grafting, NPC migrated through the host tissue 0.5-1 mm away from the implantation site, and were integrated into the white matter of the host spinal cord. Surviving NPC exhibited immunohistochemical phenotypes of astrocytes (glial fibrillary acidic protein), but not for neurons (alpha-tubulin III) or oligodendrocytes (Rip; Hybridoma Bank, Iowa City, IA, USA). Thus, NPC from the SVZ of adult rats can survive and differentiate into at least astrocytes, which can then be integrated into host tissue after transplantation into spinal cord lesions in the adult rat.     

Intrastriatal implants of mesencephalic cell suspensions in weaver mutant mice: ultrastructural relationships of dopaminergic dendrites and axons issued from the graft

Summary Dissociated cell suspensions were prepared from the ventral midbrain of normal mouse foetuses and stereotaxically implanted into the neostriatum of 2–3 months old homozygous weaver mutant mice, which are severely deficient in dopamine. In tests of amphetamine-induced turning behaviour 60 days after grafting, recipient animals displayed a rotational bias opposite to the grafted side. Prior to perfusion, which was carried out at 80 days after transplantation surgery, the grafted striata of the weaver recipients were deprived of their intrinsic mesostriatal dopamine input by local injections of 6-hydroxydopamine into the ipsilateral substantia nigra in order to selectively study the innervation derived from the graft. Grafts were found to contain an estimated 100–700 tyrosine hydroxylase immunoreactive neurones. An ultrastructural analysis demonstrated that both axons and dendrites immunoreactive for tyrosine hydroxylase extended from the graft into the recipient striatum. In the host striatum proximal to the graft (i.e. at a distance of 0.0–0.5 mm from the graft) the proportion of dendrites to axons was about 12, whereas distal to the graft (i.e. at a distance of 0.5–1.0 mm) it was 120. Graft-derived tyrosine hydroxylase immunoreactive axons were primarily found in apposition with unlabelled dendrites or spines of the recipient striatum (>90%). Graftderived dopaminergic dendrites received synaptic input from unlabelled axon terminals and were opposed to the unlabelled somata of striatal neurones in a few instances. In conclusion, this study shows that mesencephalic cell suspensions survive in the weaver striatum and provide a functional dopamine innervation which comprises both axonal and dendritic processes.     

In vivo engineering of mobilized stem cell grafts with the immunomodulatory drug FTY720 for allogeneic transplantation

The immunological attributes of stem cell grafts play an important role in the outcome of allogeneic stem cell transplants. Currently, ex vivo manipulation techniques such as bulk T‐cell depletion or positive selection of CD34⁺ cells are utilized to improve the immunological attributes of grafts and minimize the potential for graft‐versus‐host disease (GvHD). Here, we demonstrate a novel graft engineering technique, which utilizes the immunomodulatory drug FTY720 for in vivo depletion of naïve T (T_N) cells from donor G‐CSF‐mobilized grafts without ex vivo manipulation. We show that treatment of donor mice with FTY720 during mobilization depletes grafts of T_N cells and prevents lethal GvHD following transplantation in a major mismatch setting. Importantly, both stem cells and NK cells are retained in the FTY720‐treated grafts. FTY720 treatment does not negatively affect the engraftment potential of stem cells as demonstrated in our congenic transplants or the functionality of NK cells. In addition, potentially useful memory T cells may be retained in the graft. These findings suggest that FTY720 may be used to optimize the immunological attributes of G‐CSF‐mobilized grafts by removing potentially deleterious T_N cells which can contribute to GvHD, and by retaining useful cells which can promote immunity in the recipient.     

LIF对人胎脑神经干细胞体外增殖和分化的影响

目的:观察白血病抑制因子(LIF)对体外培养的人胎脑神经干细胞增殖和分化的影响。方法:用添加表皮生长因子(EGF)和碱性成纤维细胞生长因子(FGF2)的N2培养基培养人神经干细胞(hNSC)。实验分添加LIF(LIF+)组和无LIF(LIF-)组,接种12天后计数细胞集落(球)的形成率。传代培养观察120天,定期进行活细胞计数,绘制生长速率曲线。取第6代细胞球进行分化诱导,免疫荧光技术鉴别神经细胞的特异性抗原标志,并计算各细胞类型间的比例。结果:两组集落形成百分比分别为:LIF+为0.50%-0.91%;LIF-为0.49%-0.94%。两组间的差异并无显著意义(P>0.05)。在相同培养条件下,各例胎脑来源的NSC扩增速率的相差并无显著性意义(P>0.05),但LIF对NSC扩增有重要作用,刺激细胞扩增了约4000-8400倍,无分化发生;LIF-组仅为43-97倍,培养两个月后可观察到分化现象。在培养过程中观察到:LIF的作用主要表现在细胞接种传代约50-60天以后。用免疫细胞化学荧光进行分化细胞类型鉴定,计数神经元和星形胶细胞数,并计算其中神经元所占的百分比。LIF+培养为12%-83%,明显高于LIF-组的8%-23%(P<0.005),来源于海马的NSC分化为神经元的比例要高于来源于纹状体的NSC。结论:LIF能阻抑人胎脑NSC的分化,促进其体外长期增殖,其效应主要表现在接种传代培养的50-60天以后。LIF还影响NSC的分化,可显著提高分化细胞中神经元的百分比,海马源性hNSC对LIF更为敏感。     

Degeneration and graft-induced restoration of dopamine innervation in the weaver mouse neostriatum: a quantitative radioautographic study of [3H]dopamine uptake

Summary A recently introduced quantitative radioautographic technique was used to characterize the striatal dopaminergic deficit in weaver mutant mice and to evaluate the extent of DA reinnervation resulting from cell suspension grafts of fetal ventral mesencephalic tissue. Brain slices from normal mice and unilaterally grafted weaver mice were incubated in [³H]DA, in the presence of desipramine and pargyline, 3–5 months after graft surgery. Semi-thin sections from the fixed and resin-embedded slices were subsequently exposed on tritium sensitive film and afterwards dipped in nuclear emulsion for light microscope radioautography. Alternate slices were embedded in Epon for post-embedding tyrosine hydroxylase (TH) immunocytochemistry. The grain density of the film radioautographs matched well the distribution of TH positive fibers. Both methods revealed an almost complete absence of DA axons in the dorsomedial quadrant of the weaver neostriatum and an increasing density of DA innervation towards the ventrolateral areas. In the light microscope radioautographs, only the ventral striatum (i.e. nucleus accumbens and olfactory tubercle) and a narrow ventral and periventricular zone of the caudate-putamen were covered by silver grain clusters typical of DA varicosity labeling. Such labeled varicosities were nevertheless found in reduced numbers in the lateral portion of both nucleus accumbens and the olfactory tubercle. The remaining neostriatum was overlaid by diffuse silver grains, suggesting a deficient DA uptake and storage mechanism in the residual DA fibers in this region. Immunocytochemistry using antibodies specific for DA or TH provided further evidence that the residual DA innervation in the weaver neostriatum was biochemically defective. Weaver mice with grafts of ventral mesencephalic tissue in the right neostriatum showed an amphetamine-induced rotational bias to the contralateral side, which was not seen in the sham-operated animals. In contrast to the intrinsic weaver neostriatal DA innervation, DA fibers of graft origin exhibited the normal, clustered type of varicosity labeling. The computerized image analysis of silver grain density in film radioautographs was calibrated by counting these labeled varicosities in selected areas of light microscope radioautographs from the same sections. Results showed a mean DA reinnervation of neostriatal tissue surrounding the graft of about 20%, in some cases up to 80%, of the density seen in wild type mice, with a gradual decrease with distance up to 1–1.4 mm from the graft. The ventral parts of the neostriatum, which contained higher numbers of residual intrinsic DA fibers, were much more sparsely reinnervated than the dorsal and dorsomedial areas. These data show that a quantitatively significant DA reinnervation of the weaver neostriatum can be provided by fetal mesencephalic cell suspension grafts and that these DA fibers become functional, at least with respect to their DA uptake and storage mechanisms, in a neostriatal environment where intrinsic weaver DA axons are strongly deficient. However, observations in long-term weaver mice (9 months after transplantation) suggested that the graft-derived DA fiber outgrowth was reduced with time in the affected striatum, in spite of good survival of the grafted neurones.     

高压氧对小鼠皮肤移植术后脾T淋巴细胞及其表面粘附分子变化的研究

目的：探讨环孢素Ａ 和高压氧对同种异体小鼠皮肤移植排斥反应的影响。方法：采用免疫荧光染色技术和流式细胞仪,观察不同处理因素对小鼠脾淋巴细胞ＣＤ＋３ 、ＣＤ＋４ 、ＣＤ＋８ 细胞百分率及Ｔ 淋巴细胞表面粘附分子ＬＦＡ－ １（ＣＤ１１ａ／ＣＤ１８） 表达的影响。结果：高压氧组、环孢素Ａ 组、高压氧＋ 环孢素Ａ 组与对照组比较有显著差异（ Ｐ＜ ０－０１） ,且环孢素Ａ＋ 高压氧组与环孢素Ａ 组、高压氧组比较也有显著差异。结论：高压氧和环孢素Ａ 均能抑制小鼠移植排斥反应,且二者联合应用效果更显著。     

Incorporation of embryonic CA3 cell grafts into the adult hippocampus at 4-months after injury: effects of combined neurotrophic supplementation and caspase inhibition

As receptivity of the injured hippocampus to cell grafts decreases with time after injury, strategies that improve graft integration are necessary for graft-mediated treatment of chronic neurodegenerative conditions such as temporal lobe epilepsy. We ascertained the efficacy of two distinct graft-augmentation strategies for improving the survival of embryonic day 19 hippocampal CA3 cell grafts placed into the adult hippocampus at 4-months after kainic acid induced injury. The donor cells were labeled with 5'-bromodeoxyuridine, and pre-treated and grafted with either brain-derived neurotrophic factor, neurotrophin-3 and a caspase inhibitor or fibroblast growth factor and caspase inhibitor. The yield of surviving grafted cells and neurons were quantified at 2-months post-grafting. The yield of surviving cells was substantially greater in grafts treated with brain-derived neurotrophic factor, neurotrophin-3 and caspase inhibitor (84%) or fibroblast growth factor and caspase inhibitor (99% of injected cells) than standard cell grafts (26%). Because approximately 85% of surviving grafted cells were neurons, increased yield in augmented groups reflects enhanced survival of grafted neurons. Evaluation of the mossy fiber synaptic re-organization in additional kainic acid-lesioned rats receiving grafts enriched with brain-derived neurotrophic factor, neurotrophin-3 and caspase inhibitor at 3-months post-grafting revealed reduced aberrant dentate mossy fiber sprouting in the dentate supragranular layer than "lesion-only" rats at 4 months post-kainic acid, suggesting that some of the aberrantly sprouted mossy fibers in the dentate supragranular layer withdraw when apt target cells (i.e. grafted neurons) become available in their vicinity. Thus, the yield of surviving neurons from CA3 cell grafts placed into the adult hippocampus at an extended time-point after injury could be enhanced through apt neurotrophic supplementation and caspase inhibition. Apt grafting is also efficacious for reversing some of the abnormal synaptic reorganization prevalent in the hippocampus at later time-points after injury.