[From the bench to the clinic: The challenge of translating platelet production in vitro]. / Du laboratoire à l'usage clinique : le défi de la production de plaquettes in vitro.

Platelet transfusions, which are currently totally dependent on altruistic donations, are absolutely necessary to the treatment of patients with thrombocytopenia following trauma, surgery or other pathologies (especially malignancies). Producing platelets in vitro represent a major technological and scientific breathrough that would address logistical issues (supply chain, stock holding…) and medical concerns (compatibility and biosafety). The translation of this innovation will need to be accompanied by rigorous quality control, harmonised between laboratory when it comes to functionality and biosafety for use in the clinic.

In vitro-derived platelets: the challenges we will have to face to assess quality and safety.

Platelet transfusions are given to patients in hospital who have a low blood platelet count (thrombocytopenia) either because of major bleeding (following trauma or surgery) or because the bone marrow production of platelets is impaired often due to chemotherapy, infiltration with malignant cells, fibrosis or genetic disorders. We are currently entirely reliant on blood donors as a source of platelets in transfusion medicine. However, the demand for platelets continues to rise, driven by an aging population, advances in medical procedures and ever more aggressive cancer therapies, while the supply of blood donors continues to remain static. In recent years, several groups have made major advances toward the generation of platelets in vitro for human transfusion. Recent successes include results in both generating mature human megakaryocytes as well as in developing bioreactors for extracting platelets from these megakaryocytes. Platelets made in vitro could address several issues inherent to platelets derived from blood donors - the ability to scale up/down more flexibly according to demand and therefore less precarious supply line, reduction of the risk of exposure to infectious agents and finally the possibility of engineering stem cells to reduce immunogenicity. Here we define the quality control tools and suggest measures for implementation across the field for in vitro platelet genesis, to aid collaboration between laboratories and to aid production of the burdens of proof that will eventually be required by regulators for efficacy and biosafety. We will do this firstly, by addressing the quality control of the nucleated cells used to make the platelets with a particular emphasis to safety issues and secondly, we will look at how platelet function measurement are addressed particularly in the context of platelets derived in vitro.

Evaluating serial screening cultures to detect carbapenemase-producing Enterobacteriaceae following hospital admission.

BACKGROUND: Carbapenem-producing Enterobacteriaceae (CPE) are on the rise worldwide. National guidelines for the prevention and control of CPE recommend screening for the detection of asymptomatic carriers on admission. AIM: To evaluate the benefit of serial screens for detecting the carriage of CPE and other antibiotic-resistant Gram-negative bacteria following hospital admission. METHODS: All CPE screens, which were cultured on chromogenic media and the presence of a carbapenemase confirmed by polymerase chain reaction, were analysed for a six-month period. National guidelines in England recommend three serial screens for CPE separated by 48 h for admission screening for 'at-risk' patients, during which the patient is isolated. Two screening scenarios were tested. In scenario A, patients received three screens at the specified timepoints, in line with English national guidelines; in scenario B, patients received three consecutive screens, but not necessarily within the specified timepoints, during one admission. General linear models or conditional logistic regression were used to detect any significant change in the rate of carriage. FINDINGS: There was no significant increase in the detected carriage rate of CPE across any of the three timepoints in the scenarios tested. However, there was a significant increase in the detected rate of carriage of Gram-negative bacteria, Enterobacteriaceae, and resistant Enterobacteriaceae (excluding CPE) in scenario B. CONCLUSION: Three serial screens were not useful for the detection of CPE carriage on admission. The increase in the carriage rate of other Gram-negative bacteria may be explained by 'unmasking' of pre-existing carriage, or acquisition. This argues for regular screening of long-stay patients.

Gas exchange kinetics following concentric-eccentric isokinetic arm and leg exercise.

PURPOSE: To evaluate the effects of exercise velocity (60, 150, 240deg∙s-1) and muscle mass (arm vs leg) on changes in gas exchange and arterio-venous oxygen content difference (avDO2) following high-intensity concentric-eccentric isokinetic exercise. METHODS: Fourteen subjects (26.9±3.1years) performed a 3×20-repetition isokinetic exercise protocol. Recovery beat-to-beat cardiac output (CO) and breath-by-breath gas exchange were recorded to determine post-exercise half-time (t1/2) for oxygen uptake (V˙O2pulm), carbon dioxide output (V˙CO2pulm), and ventilation (V˙E). RESULTS: Significant differences of the t1/2 values were identified between 60 and 150deg∙s-1. Significant differences in the t1/2 values were observed between V˙O2pulm and V˙CO2pulm and between V˙CO2pulm and V˙E. The time to attain the first avDO2-peak showed significant differences between arm and leg exercise. CONCLUSIONS: The present study illustrates, that V˙O2pulm kinetics are distorted due to non-linear CO dynamics. Therefore, it has to be taken into account, that V˙O2pulm may not be a valuable surrogate for muscular oxygen uptake kinetics in the recovery phases.

Reduction in Clostridium difficile infection associated with the introduction of hydrogen peroxide vapour automated room disinfection.

The clinical impact of implementing hydrogen peroxide vapour (HPV) disinfection of rooms vacated by patients with Clostridium difficile infection (CDI) was evaluated. Breakpoint time series analysis indicated a significant reduction (P<0.001) in the CDI rate at the time when HPV disinfection was implemented, resulting in a reduction in the CDI rate from 1.0 to 0.4 cases per 1000 patient-days in the 24 months before HPV usage compared with the first 24 months of HPV usage. HPV should be considered to augment the terminal disinfection of rooms vacated by patients with CDI.

Isolation demand from carbapenemase-producing Enterobacteriaceae screening strategies based on a West London hospital network.

OBJECTIVE: To estimate the isolation demands arising from high-risk specialty-based screening for carbapenemase-producing Enterobacteriaceae (CPE), and the potential fraction of CPE burden detected. METHODS: Clinical specialty groups from three London hospitals were ranked by incidence of carbapenem resistance among Escherichia coli and Klebsiella spp. Contact precaution bed-days were estimated for three screening strategies: Strategy 1, 'circulation science and renal medicine'; Strategy 2, Strategy 1 plus 'specialist services'; and Strategy 3, Strategy 2 plus 'private patients'. Isolation bed occupancy rates and potential CPE detection rates were estimated. RESULTS: Of 99,105 admissions to the three hospitals in Financial Year 2014/15, Strategies 1, 2 and 3 would have screened 4371 (4.4%), 7482 (7.6%), and 13,542 (13.7%) patients, respectively. The specialties' isolation bed occupancy rates varied between 3% and 696% depending on strategy, number of consecutive tests, and whether or not pre-emptive isolation had been applied. Expected detection rates of the potential CPE burden in the hospital network would have varied between 17.1% and 47.5%. CONCLUSIONS: High-risk specialty-based screening has the potential to detect nearly half of the potential CPE burden, and would be more pragmatic than patient-level risk-factor-based screening. Pre-emptive isolation increases isolation requirements substantially. CPE screening strategies need to balance risk and resources.