Microbial safety of cellular therapeutics-lessons from over ten years’ experience in microbial safety of platelet concentrates

The ratio of nicotinic acid to nicotinamide as a microbial biomarker for assessing cell therapy product sterility

Controlling microbial risks in cell therapy products (CTPs) is important for product safety. Here, we identified the nicotinic acid (NA) to nicotinamide (NAM) ratio as a biomarker that detects a broad spectrum of microbial contaminants in cell cultures. We separately added six different bacterial species into mesenchymal stromal cell and T cell culture and found that NA was uniquely present in these bacteria-contaminated CTPs due to the conversion from NAM by microbial nicotinamidases, which mammals lack. In cells inoculated with 1 × 10⁴ CFUs/mL of different microorganisms, including USP <71> defined organisms, the increase in NA to NAM ratio ranged from 72 to 15,000 times higher than the uncontaminated controls after 24 h. Importantly, only live microorganisms caused increases in this ratio. In cells inoculated with 18 CFUs/mL of Escherichia coli, 20 CFUs/mL of Bacillus subtilis, and 10 CFUs/mL of Candida albicans, significant increase of NA to NAM ratio was detected using LC-MS after 18.5, 12.5, and 24.5 h, respectively. In contrast, compendial sterility test required >24 h to detect the same amount of these three organisms. In conclusion, the NA to NAM ratio is a useful biomarker for detection of early-stage microbial contaminations in CTPs.

International haemovigilance: what have we learned and what do we need to do next?

The International Haemovigilance Network (IHN) defines haemovigilance as 'a set of surveillance procedures covering the whole transfusion chain (from the collection of blood and its components to the follow-up of recipients), intended to collect and assess information on unexpected or undesirable effects resulting from the therapeutic use of labile blood products, and to prevent their occurrence or recurrence'. IHN, the International Society of Blood Transfusion and World Health Organization work together to support both developing and established haemovigilance systems. Haemovigilance systems provide valuable data on a range of adverse events related to blood donation and clinical transfusion, from donor syncopal events to transfusion-transmitted infections, immunological complications and the impact of human errors. Harmonised definitions for most adverse reactions have been developed and validated internationally. Definitions of pulmonary complications are again under review. Haemovigilance data have resulted in changes in policy, products and practice, and can complement and inform clinical audit and research, leading to improved blood donor safety, optimised product use and better clinical outcomes after transfusion. However, more work is needed. Not all countries have haemovigilance systems in place. More robust data and careful analysis are required to improve the understanding of the causes, occurrence and clinical outcomes of these events. Wider dissemination of results will facilitate health policy development internationally, and implementation of haemovigilance recommendations will support further important progress in blood safety.