Grafted human pluripotent stem cell-derived cortical neurons integrate into adult human cortical neural circuitry.

Several neurodegenerative diseases cause loss of cortical neurons, leading to sensory, motor, and cognitive impairments. Studies in different animal models have raised the possibility that transplantation of human cortical neuronal progenitors, generated from pluripotent stem cells, might be developed into a novel therapeutic strategy for disorders affecting cerebral cortex. For example, we have shown that human long-term neuroepithelial-like stem (lt-NES) cell-derived cortical neurons, produced from induced pluripotent stem cells and transplanted into stroke-injured adult rat cortex, improve neurological deficits and establish both afferent and efferent morphological and functional connections with host cortical neurons. So far, all studies with human pluripotent stem cell-derived neurons have been carried out using xenotransplantation in animal models. Whether these neurons can integrate also into adult human brain circuitry is unknown. Here, we show that cortically fated lt-NES cells, which are able to form functional synaptic networks in cell culture, differentiate to mature, layer-specific cortical neurons when transplanted ex vivo onto organotypic cultures of adult human cortex. The grafted neurons are functional and establish both afferent and efferent synapses with adult human cortical neurons in the slices as evidenced by immuno-electron microscopy, rabies virus retrograde monosynaptic tracing, and whole-cell patch-clamp recordings. Our findings provide the first evidence that pluripotent stem cell-derived neurons can integrate into adult host neural networks also in a human-to-human grafting situation, thereby supporting their potential future clinical use to promote recovery by neuronal replacement in the patient's diseased brain.

Human Pluripotent Stem Cell-Derived Neurons Are Functionally Mature In Vitro and Integrate into the Mouse Striatum Following Transplantation.

Human pluripotent stem cells (hPSCs) are a powerful tool for modelling human development. In recent years, hPSCs have become central in cell-based therapies for neurodegenerative diseases given their potential to replace affected neurons. However, directing hPSCs into specific neuronal types is complex and requires an accurate protocol that mimics endogenous neuronal development. Here we describe step-by-step a fast feeder-free neuronal differentiation protocol to direct hPSCs to mature forebrain neurons in 37 days in vitro (DIV). The protocol is based upon a combination of specific morphogens, trophic and growth factors, ions, neurotransmitters and extracellular matrix elements. A human-induced PSC line (Ctr-Q33) and a human embryonic stem cell line (GEN-Q18) were used to reinforce the potential of the protocol. Neuronal activity was analysed by single-cell calcium imaging. At 8 DIV, we obtained a homogeneous population of hPSC-derived neuroectodermal progenitors which self-arranged in bi-dimensional neural tube-like structures. At 16 DIV, we generated hPSC-derived neural progenitor cells (NPCs) with mostly a subpallial identity along with a subpopulation of pallial NPCs. Terminal in vitro neuronal differentiation was confirmed by the expression of microtubule associated protein 2b (Map 2b) by almost 100% of hPSC-derived neurons and the expression of specific-striatal neuronal markers including GABA, CTIP2 and DARPP-32. HPSC-derived neurons showed mature and functional phenotypes as they expressed synaptic markers, voltage-gated ion channels and neurotransmitter receptors. Neurons displayed diverse spontaneous activity patterns that were classified into three major groups, namely "high", "intermediate" and "low" firing neurons. Finally, transplantation experiments showed that the NPCs survived and differentiated within mouse striatum for at least 3 months. NPCs integrated host environmental cues and differentiated into striatal medium-sized spiny neurons (MSNs), which successfully integrated into the endogenous circuitry without teratoma formation. Altogether, these findings demonstrate the potential of this robust human neuronal differentiation protocol, which will bring new opportunities for the study of human neurodevelopment and neurodegeneration, and will open new avenues in cell-based therapies, pharmacological studies and alternative in vitro toxicology.

[Celiac artery stenosis and cephalic duodenopancreatectomy: an undervalued risk?]. / La estenosis del tronco celiaco y duodenopancreatectomía cefálica: ¿un riesgo infravalorado?

INTRODUCTION: Significant celiac trunk or artery stenosis (CAS) is normally asymptomatic. However, when the arteries of the pancreatoduodenal arcade are occluded, it could trigger a visceral ischaemia. The objective of this study is to determine whether preoperative CAS is a risk factor for developing complications in patients subjected to duodenopancreatectomy (DPC). MATERIAL AND METHODS: We have retrospectively analysed 58 consecutive patients subjected to DPC. We have associated significant CAS with post-surgical outcome. In all cases a 16-channel multidetector computed tomography (MDCT) in three hepatic phases was performed. We have reviewed the pre-surgical MDCT focusing on the morphology of the celiac artery (CA), particularly in the presence or absence of significant stenosis (>50%). RESULTS: We found CAS >50% in 13 patients (22%). The overall mortality was 5% (3 patients). Serious complications developed in 16 (28%) patients, 8 (62%) of whom belonged to the group with significant CAS (P=.004). Ten patients (17%) had a pancreatic fistula, 5 (38%) vs. 5 (11%) (P=.036); Fourteen patients (24%) needed new surgery, 7 (54%) vs. 7 (16%) (P=.009); Seven patients (12%) had a haemoperitoneum, 4 (31%) vs. 3 (7%) (P=.038), in the group with and without CAS, respectively. CONCLUSIONS: Significant radiological CAS is a risk factor of serious complications after DPC. The study of the calibre of the superior mesenteric artery (SMA) with MDCT should be routine before a DPC. The correction of a significant CAS should be evaluated preoperatively.

[Major hepatectomies are safe in patients with cholangiocarcinoma and jaundice]. / Las hepatectomías mayores en pacientes con colangiocarcinoma e ictericia son seguras.

BACKGROUND: Surgical resection is the only possibility of long term survival in patients with Klatskin tumours. However, surgical resection is a challenging problem and hepatic resection is often necessary. OBJECTIVE: The aim of our study was to assess the need for biliary drainage, resection rate and outcome of hilar cholangiocarcinoma in a single tertiary referral centre. PATIENTS AND METHODS: From 2005 to 2008, 26 patients with Klatskin tumours were identified and assessed prospectively with multidetector CT and MR cholangiography in special cases. Seven patients (27%) were deemed to be unresectable in pre-operative staging. A total of 19 surgical procedures were performed, 8 left hepatectomies, 5 right hepatectomies and 6 resections exclusively of the biliary tree. RESULTS: Resection rate was 73%, transfusion rate 53% and preoperative biliary drainage was performed only in 7 cases (37%). Major complications occurred in 11 (58%), including two post-operative deaths (10%). There were no differences in the epidemiological data, when we separately analysed the outcomes of the 9 patients with bilirubin<15 mg/dL and the 10 patients with bilirubin>15 mg/dL. Biliary drainage was required in 6 (67%) patients in the group with low bilirubin levels vs. 1(10%) in the other group (P=0.02). The mean bilirubin level in the jaundiced group was 22.1+/-3.9 vs. 4.7+/-4.3 (P<0.001) in the other group. There were no differences in the postoperative outcome between both groups. CONCLUSION: Resection and survival rates have increased recently but still carries the risk of significant morbidity and mortality. Major hepatectomies in selected patients without percutaneous biliary drainage are safe.

Mechanogenetic coupling of Hydra symmetry breaking and driven Turing instability model.

The freshwater polyp Hydra can regenerate from tissue fragments or random cell aggregates. We show that the axis-defining step ("symmetry breaking") of regeneration requires mechanical inflation-collapse oscillations of the initial cell ball. We present experimental evidence that axis definition is retarded if these oscillations are slowed down mechanically. When biochemical signaling related to axis formation is perturbed, the oscillation phase is extended and axis formation is retarded as well. We suggest that mechanical oscillations play a triggering role in axis definition. We extend earlier reaction-diffusion models for Hydra regrowth by coupling morphogen transport to mechanical stress caused by the oscillations. The modified reaction-diffusion model reproduces well two important experimental observations: 1), the existence of an optimum size for regeneration, and 2), the dependence of the symmetry breaking time on the properties of the mechanical oscillations.

[Results of hepatobiliary and pancreatic surgery according to DRG in a level 2 hospital surgery department during the years 2005-2006]. / Resultados de la cirugía hepatobiliopancreática en un servicio de cirugía de un hospital de segundo nivel según los GRD durante el bienio 2005-2006.

OBJECTIVE: To assess the results of the hepatobiliary and pancreatic surgery of a surgery department during 2005-2006 using the diagnostic related groups. MATERIALS AND METHOD: The data were obtained from the CMBD-HA of the Catalan Health Service. We assessed the frequency, hospital stay and mortality of the surgical procedures. The results were compared with the 63 public hospitals, and the 8 of them belonging to the Catalan Health Institute. RESULTS: In our area, a clear trend is observed in referrals for certain types of complex procedures on the liver, pancreas and biliary system excluding cholecystectomy with or without associated morbidities (7-11%) without exceeding the population percentage (12%). In our centre, the impact on hospital stay is more evident in complex procedures. The total savings in our centre during the years 2005-2006 compared with the XHUP hospitals group were 2212 days of hospital stay with an equivalent cost saving of more than one million euro. The frequency and the results of hospital stay and mortality of laparoscopic and open cholecystectomy were those expected for the population covered by a general hospital. The mortality in complex procedures was half of that of the whole public network or the ICS centres. CONCLUSIONS: In the complex hepatobiliary-pancreatic pathology, the mortality, and cost savings in our centre appear to be the result of, not only the high volume of procedures, but also to specialisation and factors related to the structure of the department, and surgeon training.

An osmoregulatory basis for shape oscillations in regenerating hydra.

The freshwater polyp Hydra has considerable regeneration capabilities. A small fragment of tissue excised from an adult animal is sufficient to regenerate an entire Hydra in the course of a few days. During the initial stages of the regeneration process, the tissue forms a hollow sphere. Then the sphere exhibits shape oscillations in the form of repeated cycles of swelling and collapse. We propose a biophysical model for the swelling mechanism. Our model takes the osmotic pressure difference between Hydra's inner and outer media and the elastic forces of the Hydra shell into account. We validate the model by a comprehensive experimental study including variations in initial medium concentrations, Hydra sphere sizes and temperatures. Numerical simulations of the model provide values for the swelling rates that are in agreement with the ones measured experimentally. Based on our results we argue that the shape oscillations are a consequence of Hydra's osmoregulation.

[Role of intra-operative echography and computed tomography with multiple detectors in the surgery of hepatic metastases: a prospective study]. / Papel de la ecografía intraoperatoria y la tomografía computarizada con multidetectores en la cirugía de las metástasis hepáticas: estudio prospectivo.

OBJECTIVES: To study the performance of the intraoperative ecography in the diagnosis of new liver metastases in the era of computerized tomography (CT) with multidetectors and its impact on the surgical operation. PATIENTS AND METHOD: Between February 2005 and April 2006 patients with resectable liver metastases where studied prospectively in a multidisciplinary meeting (surgeons, radiologist, oncologist). The preoperative CT findings were compared with the intraoperative findings and ultrasound study and the results of the surgical operation. RESULTS: Forty-five candidates for curative surgery had a total of 171 hepatic lesions. CT correctly detected 115 lesions with a sensitivity of 67%, and a positive predictive value of 97%, with a false negative rate of 33% and false positive rate of 2%. In 5 patients intraoperative findings were the cause of changing the surgical procedure, three patients were unresectable (rate of resectability of 93%) and two patients needed a larger hepatic resection. CONCLUSIONS: CT with multidetectors and multidisciplinary meetings are the most important factors in the decision making of surgery of liver metastases with a high resectability rate. Intraoperative ecography is useful for the detection of 10% more liver metastases, but rarely involves a change in the surgical procedure.