Clinical use of the embryonic brain tissue grafts in epilepsy

Brain and spinal nerve tissue grafts of 5- to 10-week human embryos obtained during legal abortions were transplanted in the last 2.5 years to 15 patients with epilepsy and other paroxysmal disorders. Different forms of epilepsy were found in these patients. The latter were examined to determine their somatic, neurological, and psychological status. This made it possible to divide the patients into groups. Embryonic nerve tissue transplantation (ENTT) was found to be among efficient ways of treatment of patients with different forms of epilepsy. The positive results differed by degree and attested to the marked recovery activity of the impaired central nervous system (CNS). In patients with epilepsy resistant to medical treatment, embryonic nerve tissue implantation was found to cause a stable remission lasting from eight months to 2.5 years in 12 patients and to significantly decrease the frequency of seizures in three patients. Improvement of cognitive functions was observed in all cases. The changes in EEG were always positive, sometimes lagging behind the clinical effect, though more often progressing parallel to it. The possible biological mechanisms causing the above positive effect are discussed.     

Effect of embryonic brain tissue transplantation on structural changes in the rat brain after craniocerebral trauma

The effect of homotopic allotransplantation of embryonic cerebral cortex tissue on structural changes in the brain were studied on rats who had suffered a severe craniocerebral trauma (CCT) and subsequent traumatonesis of an injured region. Using Nissl and Golgi-Cox techniques, we showed that the presence of a viable graft in the cavity created by the traumatonesis procedure prevented formation of coarse gliofibrous expansions and extensive dead zones within the perifocal region of the injury locus. Transplantation performed immediately after the CCT and traumatonesis appeared to be most effective. In this case, the graft growth was more intensive and it was better integrated into the recipient's brain; branching of neurons in the graft was more abundant, and their dendrites were densely covered with spines. Thus, the use of early transplantation prevents the development of destructive and dystrophic changes evoked by severe CCT and can be regarded as a promising direction in neurosurgical practice.Neirofiziologiya/Neurophysiology, Vol. 27, No. 5/6, pp. 350–360, September–December, 1995.     

Transplantation of embryonal anlagen of the human neocortex into the brain of the rat

A possibility for transplanting anlages of human embryonal neocortex into mature rat brain has been studied. Light- and electron-microscopic investigations demonstrate that the embryonal tissue of the human neocortex implants into the cerebral grey and white substance of mature rats. In the grafts cellular elements proliferate and differentiate, neuropil is formed. These results open certain perspectives for modelling investigations on histogenesis of neural tissues and on studying possibilities for clinical use of grafts of the human embryonal brain.     

间充质干细胞在造血干细胞移植中的应用

间充质干细胞(MSCs)是一种具有自我更新和多向分化潜能的成体干细胞,存在于骨髓、脂肪组织、脐血及多种胎儿组织.它可分泌多种细胞因子及生长因子,促进造血干细胞(HSC)的增殖与分化.MSCs还具有免疫调节、抗炎和组织修复作用,可减轻移植物抗宿主病(GVHD)及其他移植相关并发症.     

Retinoic acid enhances and depresses in vitro development of cartilaginous bone anlagen in embryonic mouse limbs

Summary Forelimbs of Day 11 and Day 12 embryonic mice were excised and cultured for 3 d in the presence of either 0.25 μg (8×10⁻⁷ M), 0.5 μg(1.7×10⁻⁶ M), or 1.0 μg (3.3×10⁻⁶ M) of all-rans retinoic acid (RA) per milliliter of culture medium. Cultured limbs were fixed, stained, and mounted whole on glass slides and evaluated with computerized optical image analysis for RA-induced effects on the area and shape of the total limb and individual bone anlagen. Relative effects of RA on total bone, soft tissue, long bone, and paw regions were also examined. With Day 11 forelimbs total bone area was increased by 10.5% by the low dose of RA. The increase was mostly in long bones and at the expense of soft tissue. Total bone area was increased 9.3% with Day 12 forelimbs. This increase was primarily in the paw. The high dose of RA decreased Day 11 forelimb area, primarily affecting long bones. Day 12 forelimbs were not significantly affected by the high dose of RA. Effects of the imtermediate dose were primarily limited to reduction in soft tissue area. Long bone:paw and soft tissue: bone ratios reflected these effects. The high dose produced a consistent rounding or shortening of Day 11 forelimb bones. On Day 12 0.5 μg/ml RA produced an inconsistent pattern of rounding of bone anlagen. Treatment with the high dose on Day 12 produced angular rather than rounded contours in many cases, as indicated by shape factor values closer to zero than obtained with controls. These data show that direct exposure to RA can affect both the size and shape of bone anlagen of the developing limb; the low dose enhances and the high dose depresses development. The results support previous studies which suggest that RA may play a critical role in the control of cell activities such as cell migration, proliferation, and cytodifferentiation in the development of the cartilaginous bone anlagen.     

Whole eyes reconstituted from embryonic half anlagen: alterations in donor-derived territories in Xenopus pigment chimerae

Grafts from pigmented donor embryonic eye rudiments into albino hosts were used to chart i) fates of local cell groups in three positions in whole eye rudiments, and ii) alterations in graft-derived territories when the posterior half of the rudiment was ablated. Small pigmented patches of graft-derived tissue were conspicuous in albino embryos and tadpoles, enabling us to directly monitor their location and size in the eyes of living animals. The three (right eye) positions marked by pigmented grafts were dorsal (12 o'clock), anterior (3 o'clock), and anteroventral (5 o'clock). Control transplants reared without secondary ablation produced black sector territories in pigment retinal epithelium and iris at corresponding 12 o'clock or 2 o'clock or 4 o'clock positions on the larval eyeball. In the experimental series posterior half-anlagen were ablated. The remaining anterior half-anlagen, each containing a pigmented graft, reconstituted spherical larval eyeballs of reduced size. During healing, donor-derived pigmented sector territories remained coherent, but were altered in position and size compared to controls. Dorsal cells (from 12 o'clock grafts) appeared to move rapidly along the newly formed cut edge into the wound and went on to form expanded black sectors in posterior eye regions. More gradually, sector territories of anterior cells (3 o'clock grafts) and anteroventral cells (5 o'clock grafts) shifted toward dorsal in a counterclockwise direction. Thus all three types of graft derived pigment territories were altered in eye anlage fragments as they healed to form half-size spherical eyes.     

Homotopic transplantation of embryonic neocortical tissue into the brain of adult rats after its damage

Structural characteristics (survival, growth, connections) have been studied in the transplant of the cerebral cortex tissue in Wistar rat embryos (18-day-old), implanted into the brain of mature rats of the same line at various time after a partial lesion of the sensomotor cortex. In 3-5 months after transplantation the light microscopy methods demonstrate that spatial interconnections of the transplant and the injured brain of the recipient depend on time interval between the cerebral lesion and transplantation of the embryonal nervous tissue. Horseradish peroxidase (HP) is ionophoretically injected into the recipient's cerebral tissue away from the place of transplantation. In the transplant retrogradely labelled HP neurons are revealed. This demonstrates efferent connections of the implanted tissue with the host's brain. Presence of the anterogradely labelled nervous terminals in the transplant tissue demonstrates existence of afferent connections of the transplant with the recipient's tissue. Possible mechanisms of survival, growth and formation of connections of the transplant in the injured brain of the mature animal are discussed.     

Islet cell engraftment and control of diabetes in rats after transplantation of pig pancreatic anlagen

The insufficient supply of tissue, loss posttransplantation, and limited potential for expansion of beta-cells restrict the use of islet allotransplantation for diabetes. A way to overcome the supply and expansion problems is to xenotransplant embryonic tissue. We have shown that whole rat pancreatic anlagen isotransplanted into the omentum of rats, or xenotransplanted into costimulatory blocked mice, undergo growth and differentiate into islets surrounded by stoma without exocrine tissue. Isotransplants normalize glucose tolerance in diabetic hosts. Here, we show that embryonic day 29 porcine pancreas transplanted into the omentum of adult diabetic rats undergoes endocrine tissue differentiation over 20 wk and normalizes body weights and glucose tolerance. Unlike rat-to-rodent transplants, individual alpha- and beta-cells engraft without a stromal component, and no immunosuppression is required for pig-to-rat transplants. Herein is described a novel means to effect the xenotransplantation of individual islet cells across a highly disparate barrier.     

The fate ofDrosophila hydei anlagen in heteroplastic transplantations

Summary Imaginal discs and larval brains of wildtype andlethal (3) giant larvae ofDrosophila hydei were transplanted into adult foreign hosts and examined after about 2 weeks. The transplants behaved very differently in different host species, viz. 6 species ofDrosophila, 5 other species of Diptera, and 3 species belonging to the Coleoptera or Dictyoptera, whereby the degree of incompatibility was more or less correlated with taxonomic distances. One notable exception was found in the cheese skipper,Piophila casei, an entirely compatible host.     

Commissure formation in the embryonic insect brain

The primary axon scaffold of the insect brain is established early in embryogenesis and comprises a preoral protocerebral commissure, a postoral tritocerebral commissure and longitudinal fiber pathways linking the two. In both grasshopper and fly its form is approximately orthogonal and is centered around the stomodeum. We show how pioneer fibers from the protocerebrum and tritocerebrum cross the brain midline directly via their respective commissures. The deutocerebrum, however, lacks its own commissure and we describe how deutocerebral pioneers circumnavigate the gut to cross the midline either via the protocerebral commissure or the tritocerebral commissure. In contrast to all other commissures of the central nervous system, the protocerebral commissure persists, albeit in reduced form, in the commissureless mutation in the fly. Besides the com gene, a further, as yet unidentified, mechanism must regulate this commissure. The formation of the tritocerebral commissure involves labial, a member of the Hox gene group. Genetic rescue experiments in labial mutants reveal that the formation of this commissure can be rescued by all other Hox genes except Abdominal-B. However, only in the labial and Deformed null mutants are the commissures associated with the respective expression domains (tritocerebral, mandibular, respectively) absent. This suggests that the molecular mechanisms regulating postoral brain commissure formation are distinct from those in the neuromeres of the ventral nerve cord.     

Inductive patterning of the embryonic brain in Drosophila

In vertebrates (deuterostomes), brain patterning depends on signals from adjacent tissues. For example, holoprosencephaly, the most common brain anomaly in humans, results from defects in signaling between the embryonic prechordal plate (consisting of the dorsal foregut endoderm and mesoderm) and the brain. I have examined whether a similar mechanism of brain development occurs in the protostome Drosophila, and find that the foregut and mesoderm act to pattern the fly embryonic brain. When the foregut and mesoderm of Drosophila are ablated, brain patterning is disrupted. The loss of Hedgehog expressed in the foregut appears to mediate this effect, as it does in vertebrates. One mechanism whereby these defects occur is a disruption of normal apoptosis in the brain. These data argue that the last common ancestor of protostomes and deuterostomes had a prototype of the brains present in modern animals, and also suggest that the foregut and mesoderm contributed to the patterning of this 'proto-brain'. They also argue that the foreguts of protostomes and deuterostomes, which have traditionally been assigned to different germ layers, are actually homologous.     

Effect of transplantation of embryonic neural tissue on the dynamics of brain edema following experimental craniocerebral trauma

The effect of transplantation of embryonic neural tissue (ENT) on the dynamics of brain edema following heavy craniocerebral trauma (CCT) made to the left parietotemporal area was studied in rats. The brain tissue impedance was measured in the damaged and contralateral hemispheres 1 to 30 days after the trauma in the animals of three groups: (i) without any procedures after the CCT, (ii) with surgical treatment of the damaged brain area, and (iii) with transplantation of 1–2 mm³ sensorimotor cortex fragments from 18-day-old rats grafted into the cavity created by this treatment. At the first day after CCT, the impedance in the damaged hemisphere decreased by 30–37%, while the impedance in the contralateral hemisphere decreased approximately by 20%, compared with the control, which was evidence of the development of intensive generalized edema. In the group of animals with the ENT transplantation, the edema involuted noticeably faster than in the other two groups: the mean impedance value reached 97.9% of the control value (before the damage) already by the 7th post-traumatic day. Complete recovery of the impedance by the 30th day was observed only in the animals with transplantation. The adequacy of an impedancemetric technique for investigation of the dynamics of water-electrolyte re-distribution in the brain tissue, and the mechanisms underlying corrective effect of ENT transplantation on the edema dynamics in the post-traumatic period are discussed.     

Changes in the esterase activity and isoenzyme spectrum following the transplantation of embryonic nerve tissue into the brain of adult rats

Nervous tissue of 17-days old rat embryos was transplanted into lateral ventricle of the brain of adult rats. 15 days after transplantation esterase activity was analyzed from transplant tissue and flanking regions of cerebral cortex. Isoenzymes were shown to activate their activity after embryonic tissue transplantation either in transplants or flanking regions. These changes result obviously from the effect of substances, synthesized by transplant.     

Sex differences in the regulation of embryonic brain aromatase

Oestrogen formed from androgen by aromatization plays a critical role in the sexual differentiation of the male brain and behaviour. A question which has still to be answered is what regulates the gender-specific changes in aromatase activity forming oestrogen during sensitive periods of brain growth. Using a primary cell culture technique and sexed embryos, we have shown that in the fetal mouse brain, oestrogen formation in the male is neuronal rather than glial and aromatase activity is regionally localized, being higher in the hypothalamus than in the cortex. The aromatase activity measured from cells in culture has the same enzyme binding affinity (apparent K_m 40 nM) as intact brain samples. Neurones developing in the embryonic male brain (embryonic day (ED) 15) contain higher aromatase activity (V_max, 895 fmol/h/mg protein) than the female (V_max, 604). Although a sex difference exists at early stages of embryonic development (ED 13), the embryonic aromatase system is regulated by steroids later in fetal development. The developing aromatase-containing neuroblasts probably form processes which connect to other aromatase neurones. Immunoreactive staining with an aromatase polyclonal antibody identifies an increase in numbers of aromatase-immunoreactive hypothalamic neuronal cell bodies following testosterone treatment. Testosterone treatment also causes both stimulation of neurite growth and branching as well as functional maturation of aromatase neurones. In particular, there is an increase in aromatase activity per neurone as well as a dramatic increase in the number of neurones expressing the enzyme. Both the functional and morphological changes depend on androgen receptor stimulation for several days in vitro. This conclusion is supported by colocalization studies which reveal a high number of fetal hypothalamic aromatase neurones co-expressing androgen receptor. We conclude that testosterone influences the growth of male hypothalamic neurones containing aromatase at a sensitive period of brain development. Endogenous steroid inhibitors of aromatase, probably formed within the neuroglia, also play a role in the control of oestrogen production. An endogenous 5-reduced metabolite of testosterone, 5-androstanedione, is almost as potent in inhibiting neuronal hypothalamic aromatase activity (K_i = 23 nM) as the synthetic non-steroidal inhibitors such as the imidazole, fadrozole, and the triazoles, arimidex and letrozole. It is clear that the oestrogen-forming capacity of the male hypothalamus has the special characteristics and plasticity of regulation which could affect brain differentiation at specific steroid-sensitive stages in ontogeny.