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Previous studies have shown that intrastriatal transplants of dopamine (DA)-rich fetal ventral mesencephalic (VM) tissue can correct denervation-induced changes in the cellular expression of neuropeptide and receptor mRNAs in the rat Parkinson model. However, with the standard transplantation approach normalization of all cellular parameters has not been obtained. This may be due either to the incomplete striatal reinnervation achieved by these transplants, or to the ectopic placement of the grafts. In the present study we have used a microtransplantation approach to obtain a more complete reinnervation of the denervated striatum (20 micrograft deposits spread over the entire structure). Neurons were also implanted directly into the substantia nigra. In rats with multiple intrastriatal VM transplants the lesion-induced upregulation of mRNAs encoding for preproenkephalin (PPE), the D2-type DA-receptor, and the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD67) was normalized throughout the striatum, whereas the lesion-induced downregulation of preprotachykinin mRNA was unaffected. Intranigral grafts of either fetal DA-rich VM tissue or GABA-rich striatal tissue did not induce any changes in striatal neuropeptide and D2-receptor mRNA expression despite significant behavioral improvement. Comparison of the behavioral data with levels of neuropeptide expression showed that in rats with intrastriatal VM transplants a complete normalization of striatal PPE and GAD67 mRNA expression did not translate into a complete recovery of spontaneous motor behaviors. The results show that extensive DA reinnervation of the host striatum by multiple VM microtransplants is insufficient to obtain full recovery of all lesion-induced changes at both the cellular and the behavioral level. A full reconstruction of the nigrostriatal pathway or, alternatively, modulation of basal ganglia function by grafting in non-striatal regions may be required to further improve the functional outcome in the DA-denervated brain. [Copyright &y& Elsevier]

Background: Even more than hospital care in general, intensive care and mechanical ventilation capacities and its utilization in terms of rates, indications, ventilation types and outcomes vary largely among countries. We analyzed complete and nationwide data for Germany, a country with a large intensive care sector, before, during and after the COVID-19 pandemic., Methods: Analysis of administrative claims data, provided by the German health insurance, from all hospitals for all individual patients who were mechanically ventilated between 2019 and 2022. The data included age, sex, diagnoses, length of stay, procedures (e.g., form and duration of mechanical ventilation), outcome (dead vs. alive) and costs. We included all patients who were at least 18 years old at the time of discharge from January 1st, 2019 to December 31st, 2022. Patients were grouped according to year, age group and the form of mechanical ventilation. We further analyzed subgroups of patients being resuscitated and those being COVID-19 positive (vs. negative)., Findings: During the four years, 1,003,882 patients were mechanically ventilated in 1395 hospitals. Rates per 100,000 inhabitants varied across age groups from 110 to 123 (18-59 years) to 1101-1275 (>80 years). The top main diagnoses were other forms of heart diseases, pneumonia, chronic obstructive pulmonary disease (COPD), ischemic heart diseases and cerebrovascular diseases. 43.3% (437,031/1,003,882) of all mechanically ventilated patients died in hospital with a remarkable increase in mortality with age and from 2019 to 2022 by almost 5%-points. The in-hospital mortality of ventilated COVID-19 patients was 53.7% (46,553/86,729), while it was 42.6% (390,478/917,153) in non-COVID patients. In-hospital mortality varied from 27.0% in non-invasive mechanical ventilation (NIV) only to 53.4% in invasive mechanical ventilation only cases, 59.4% with early NIV failure, 68.6% with late NIV failure, to 74.0% in patients receiving VV-ECMO and 80.0% in VA-ECMO. 17.5% of mechanically ventilated patients had been resuscitated before, of whom 78.2% (153,762/196,750) died. Total expenditure was around 6 billion Euros per year, i.e. 0.17% of the German GDP., Interpretation: Mechanical ventilation was widely used, before, during and after the COVID-19 pandemic in Germany, reaching more than 1000 patients per 100,000 inhabitants per year in the age over 80 years. In-hospital mortality rates in this nationwide and complete cohort exceeded most of the data known by far., Funding: This research did not receive any dedicated funding., Competing Interests: C.K. received lecture fees from Maquet, Rastatt, Germany. C.K. received travel grants and fees for advisory board meetings from Xenios (Germany) and Bayer (Germany). C.K. is the speaker of the German register of ICUs and Member of the Government Commission on Modern and Needs-based Hospital Care; Member of the Expert Commission on “Resilience and Health”. F.K., C.B. and J.W. work for the National Association of Statutory Health Insurance Funds (GKV-Spitzenverband). T.B. reports no conflicts of interest. W.W. received grants from Löwenstein Medical, Germany, Philips/Respironics, USA and GCI, Great Britain and personal fees from AstraZeneca, Germany, Sentec, Switzerland, Chiesi, Germany, Boehringer Ingelheim, Germany, Novartis, Germany, BioNTech Europe GmbH Philips/Respironics, USA. R.B. reports honoraria for presentations on the ongoing hospital reform in Germany. He is Member of the Government Commission on Modern and Needs-based Hospital Care; Member of the Expert Commission on “Resilience and Health”; and Chair of the Scientic Advisory Board, Federal Association of General Local Sickness Funds., (© 2024 The Author(s).)

The aim of this study was to determine whether the growth of axons along the nigrostriatal pathway from fetal dopamine cells, transplanted into the substantia nigra of young postnatal 6-OHDA-lesioned rats, is dependent on the age of the host brain. Neonatal rats were lesioned bilaterally by intraventricular injection of 6-OHDA at postnatal day 1 (P1) and received grafts of E14 ventral mesencephalon at day 3 (group P3), day 10 (group P10), or day 20 (group P20) into the right substantia nigra. One lesioned group was left untransplanted. Six months after surgery the animals were subjected to analysis of drug-induced rotation following injection of amphetamine, apomorphine, a D1 agonist (SKF38393), or a D2 agonist (Quinpirole). Animals transplanted intranigrally at day 3 and day 10 showed a strong amphetamine-induced rotational bias toward the side contralateral to the transplant. Animals transplanted into substantia nigra at P20, like the lesioned control animals, showed no rotational bias. Apomorphine and selective D1 and D2 agonists induced ipsilateral turning behavior in the P3 and P10 group, but not in the P20 or the lesion control groups. Immunofluorescence histochemistry in combination with retrograde axonal tracing, using FluoroGold injection into the ipsilateral caudate-putamen showed colocalization of tyrosine hydroxylase and FluoroGold in large numbers of transplanted neurons in the animals transplanted at postnatal day 3 and postnatal day 10, which was not observed in the group P20. The lesion control group showed a 90% complete lesion of the TH-positive cells in the substantia nigra while largely sparing the neurons in the ventral tegmental area. The results indicate that intranigral grafts can be placed accurately and survive well within the substantia nigra region at various time points during postnatal development. Furthermore, embryonic dopamine neurons have the ability to extend axons along the nigrostriatal pathway and reconnect with the dopamine-depleted striatum when transplanted at postnatal day 3 and postnatal day 10, but not at postnatal day 20., (Copyright 1999 Academic Press.)

Intrastriatal transplantation of fetal ventral mesencephalon (VM) is currently explored as a potential clinical therapy in Parkinson's disease (PD). Although providing substantial benefit for the patient, behavioral recovery so far obtained with intrastriatal VM grafts is not complete. Using the 6-hydroxydopamine lesion model of PD, we show here that near-complete restoration of the striatal dopamine (DA) innervation can be achieved by multiple intrastriatal microtransplants of fetal DA cells; nevertheless, complete recovery in complex sensorimotor behaviors was not obtained in these animals. In line with the current model of basal ganglia function, this suggests that the lesion-induced overactivity of the basal ganglia output structures, i.e., the substantia nigra (SN) and the entopeduncular nucleus, may not be completely reversed by intrastriatal VM grafts. In the present study, we have transplanted fetal VM tissue or fetal striatal tissue, as a source of DA and GABA neurons, respectively, into the SN of DA-depleted rats. Intranigral VM grafts induced behavioral recovery in some sensorimotor behaviors (forelimb akinesia and balance tests), but the effect did not exceed the recovery observed after intrastriatal VM grafts. Intranigral grafts of striatal tissue induced a pattern of functional recovery which was distinctly different from that observed after intranigral VM grafts, and recovery in coordinated forelimb use in the paw-reaching test was even more pronounced than after intrastriatal transplantation of VM cells. Combined transplantation of DA neurons into the striatum and GABA-rich striatal neurons into the SN induced additive effects of behavioral recovery observed in the forelimb akinesia test. We propose that intranigral striatal transplants, by a GABA-mediated inhibitory action, can reduce the overactivity of the host SN projection neurons and can induce significant recovery in complex motor behavior in the rat PD model and that such grafts may be used to increase the overall functional efficacy of intrastriatal VM grafts., (Copyright 1999 Academic Press.)

Embryonic striatal precursors grafted into the lesioned adult host striatum show limited integration with little migration and restricted efferent projections. In the present study, the influence of an immature striatal environment on the integrative capacity of grafted neuroblasts was examined after transplantation of striatal progenitors into the striatum at different stages of postnatal development. Mouse progenitors, derived from embryonic day 13.5-14 lateral or medial ganglionic eminence or the cerebellar primordium, were transplanted as a single cell suspension into the developing postnatal day 1, 7 and 21 rat striatum. The grafted cells and their axonal projections were visualized using antibodies raised against the mouse-specific neural markers, M6 and M2. Cells from the lateral (but not the medial) ganglionic eminence showed a remarkable capacity to innervate selectively the striatal target structures, globus pallidus, entopeduncular nucleus and substantia nigra, reminiscent of endogenous striatal neurons, which is not observed after grafting into adult hosts. M6 and M2-immunopositive cellular profiles from both the lateral and medial ganglionic eminences were observed to have migrated extensively away from the injection site, in contrast to the cerebellar precursors which remained clustered at the implantation site. Cells from the lateral ganglionic eminence were largely confined within the striatal complex where they developed striatal characteristics, displaying expression of DARPP-32, the 32,000 mol. wt dopamine- and cyclic AMP-regulated phosphoprotein, whereas cells from the medial ganglionic eminence had migrated caudally along the internal capsule and were observed predominantly in the globus pallidus and thalamus, in addition to the striatum. The cells located outside the striatum were all DARPP-32 negative. The improved integration and increased projection capacity of the lateral ganglionic eminence precursors grafted into postnatal day 1 hosts gradually declined as the host advanced into later stages of development (postnatal day 7), and in postnatal day 21 hosts the grafted striatal precursors behaved similarly to grafts implanted into adult recipients. These results demonstrate the specific capacity of embryonic striatal progenitors to integrate into the developing basal ganglia circuitry during early postnatal development, and that the extent of neuronal and glial integration and graft host connectivity declines when the host has developed beyond the first postnatal week.

A CNS-derived conditionally immortalized temperature-sensitive neural progenitor (CINP) cell line was used to generate NGF-secreting cells suitable for intracerebral transplantation. The cells were transduced by repeated retroviral infection, using a vector containing the mouse NGF cDNA under the control of the LTR promoter. Subcloning at the permissive temperature (33 degrees C) identified a highly NGF-secreting clone (NGF-CINP), which contained multiple copies of the transgene and released NGF at a rate of 2 ng/hr/10(5) cells in vitro, both at 33 and 37 degrees C, which was approximately 1 order of magnitude higher than what was possible to achieve in the heterogeneously infected cell cultures. After transplantation to the brain, the NGF-CINPs differentiated into cells with a predominant glia-like morphology and migrated for a distance of 1-1.5 mm from the implantation site into the surrounding host tissue, without any signs of overgrowth and tumor formation. Grafts of NGF-CINP cells implanted into the septum of adult rats with complete fimbria-fornix lesion blocked over 90% of the cholinergic cell loss in the medial septum and grafts placed in the intact striatum induced accumulation of low-affinity NGF receptor positive fibers around the implantation site. Expression of the NGF transgene in vivo was demonstrated by RT-PCR at 2 weeks after grafting. It is concluded that the immortalized neural progenitors have a number of advantageous properties that make them highly useful experimental tools for gene transfer to the adult CNS.

Methods for the assessment of akinesia in the unilateral rat Parkinson model have so far been lacking. The experiments reported here evaluate the usefulness of a new "stepping test" to monitor forelimb akinesia in rats with unilateral 6-hydroxydopamine (6-OHDA) lesions of the mesencephalic dopamine (DA) system, and to assess the ability of DA-receptor agonists and fetal DA neuron transplants to reverse these deficits. The 6-OHDA lesion induced marked and long-lasting impairments in the initiation of stepping movements with the contralateral paw. Systemic injections of low doses (chosen to be subthreshold for induction of rotation) of the mixed D1 and D2 receptor agonist apomorphine, the D1-selective agonist SKF 38393, and to a lesser extent also the D2-selective agonist quinpirole were effective in reversing these deficits. Similar effects was seen after a subrotational dose of L-dopa, whereas amphetamine had no effect. Fetal nigral transplants, implanted as multiple deposits in the ipsilateral caudate-putamen and substantia nigra, restored initiation of stepping to a similar degree as the DA agonists. Nigral grafts placed in substantia nigra alone were also effective, although the improvement was less pronounced. Apomorphine, at a dose effective in the lesion-only animals, had no additive effect in the grafted rats, whereas amphetamine appeared to further improve stepping in the rats with intranigral transplants. Identical experiments were performed on skilled forelimb use in the so-called staircase test. Interestingly, neither the DA agonist drugs nor the nigral transplants had any effects on the lesion induced deficits in this more complex task. The results show that forelimb stepping is a highly useful test to monitor lesion-/and transplant-induced changes in forelimb akinesia, a behavioral parameter that may be analogous to limb akinesia and gait problems seen in patients with Parkinson's disease.

Shortcomings of current techniques used for the intracerebral transplantation of ventral mesencephalic dopamine neurons include low graft survival, high variability, considerable implantation trauma and suboptimal graft integration. In order to overcome these limitations, we have adopted a microtransplantation approach which allows precise and reproducible implantation of ventral mesencephalon cell suspensions at single or multiple sites with minimal trauma and improved survival and integration of the grafted neurons [Nikkhah et al. (1994) Brain Res. 633, 133-143]. The present study was undertaken to determine the influence of different grafting parameters as well as the time-course of development of micrografted dopaminergic neurons and to devise an optimal microtransplantation procedure in the rat Parkinson model, Rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal pathway received four graft deposits of either 0.25, 0.5, 1.0 or 2.0 microliters along four injection tracts (150,000 cells/microliters) using either a glass capillary (o.d. 50-70 microns) or a regular cannula (o.d. 0.50 mm, metal cannula grafts). At one, two and 12 weeks postgrafting (capillary grafts) and at 12 weeks postgrafting (metal cannula grafts) dopamine neuron survival and graft volumes were measured and the implantation trauma assessed by glial fibrillary acidic protein expression. The results demonstrate that single deposits of 50,000-75,000 cells in 0.5 microliter, implanted with a glass capillary, provide the best environment both for dopaminergic and non-dopaminergic neuron survival. Grafts implanted with the glass capillary showed much weaker long-term glial fibrillary acidic protein expression along the injection tract and around the implants than was the case in grafts implanted with the thicker metal cannula. Optimal graft integration and minimal disturbances of host brain structures can reliably be achieved by small-sized implants (20,000-35,000 cells/deposit). Tyrosine hydroxylase-positive fiber outgrowth from micrografted dopaminergic neurons was seen not only in the surrounding caudate-putamen, but also along white matter tracts into the nucleus accumbens and the overlying cerebral cortex. Spreading of dopaminergic micrografts over multiple small deposits rather than increasing the volume of single grafts gave more extensive reinnervation of the entire host striatum. The micrografting technique provides a useful tool to improve graft-host interactions in the rat Parkinson model, and it allows more precise and reproducible quantitative studies on dopamine neuron survival and growth in intrastriatal ventral mesencephalon transplants. This technique should also be highly useful for the intracerebral implantation of cells derived from primary cultures or cell lines [Gage and Fisher (1991) Neuron 6, 1-12].

Neural transplantation in experimental Parkinsonism has so far focused on the ectopic placement of fetal ventral mesencephalic (VM) neurons into the dopamine-denervated caudate-putamen. VM grafts are effective in restoring dopamine neurotransmission in the grafted caudate-putamen and in partial amelioration of behavioral deficits. Recent pharmacological and physiological data have provided strong evidence that dopamine released from dendrites of the substantia nigra pars compacta (SNc) neurons within the pars reticulata (SNr) plays an important role in the regulation of the basal ganglia output pathways. Using a novel microtransplantation approach, multiple small cell suspension grafts (250 nl) derived from the VM of E14 rat embryos were implanted into the SNr of unilaterally 6-hydroxydopamine-lesioned rats. Behavioral changes in drug-induced rotation asymmetry were monitored for up to 14 weeks postgrafting, followed by a quantitative assessment and correlation of tyrosine hydroxylase (TH)-positive cell survival. The reduction in rotational asymmetry caused by the intranigral VM grafts was 64% for SKF 38393 (D1 agonist), 54% for apomorphine (mixed D1 and D2 agonist), and 67% for quinpirole (D2 agonist) when compared to a control spinal cord graft group. By contrast, amphetamine-induced rotation was completely unaffected. The correlation between number of TH-positive cells and behavioral compensation was highest for the D1 agonist (R = -0.729), though clear-cut also for the mixed D1/D2 agonist apomorphine (R = -0.664) and the D2 agonist quinpirole (R = -0.642). Favorable morphological features of the VM micrografts included extensive migration of the dopaminergic neurons into the host SNr and the formation of dense patches of dendrite-like TH-positive terminal networks within the SNr. The results demonstrate a novel pattern of behavioral recovery induced by intranigral VM transplants in the rat Parkinson model. This may have important implications for the understanding of how the nigrostriatal dopamine system influences motor control in the basal ganglia as well as for the development of optimal transplantation strategies in Parkinson's disease.