Impact of Different Cooling Methods on the Stability of Peripheral Blood Mononuclear Cells (PBMCs)

During cryopreservation of peripheral blood mononuclear cells (PBMCs), there are several recognized cooling methods, which include different cooling rates that might influence the stability of the PBMCs. This chapter will focus on three cooling methods trialled and will describe the different principles they are based on and the outcomes. One cooling method is based on repeatable −1°C/min cooling rate that requires only isopropyl alcohol (method A). The second cooling method is based on the cooling rate of −1° C/min solely (method B). The third cooling method is based on a user-predefined programmable controlled rate of freezing (method C). The first method was discontinued for safety reasons. A small comparative study was performed using 12 cell preparation tubes (CPT) using methods B and C. Cell Viability was measured based on the difference between pre-thaw and post-thaw viability percentages that were obtained from the flow cytometry. From our data, we conclude that although there were no significant differences in the outcomes of the comparative study of cooling methods, the use of either method B or C are the most suitable for long-term storage that will preserve the quality of the sample suitable for future research and clinical applications

The QChip1 knowledgebase and microarray for precision medicine in Qatar

Risk genes for Mendelian (single-gene) disorders (SGDs) are consistent across populations, but pathogenic risk variants that cause SGDs are typically population-private. The goal was to develop "QChip1," an inexpensive genotyping microarray to comprehensively screen newborns, couples, and patients for SGD risk variants in Qatar, a small nation on the Arabian Peninsula with a high degree of consanguinity. Over 108 variants in 8445 Qatari were identified for inclusion in a genotyping array containing 165,695 probes for 83,542 known and potentially pathogenic variants in 3438 SGDs. QChip1 had a concordance with whole-genome sequencing of 99.1%. Testing of QChip1 with 2707 Qatari genomes identified 32,674 risk variants, an average of 134 pathogenic alleles per Qatari genome. The most common pathogenic variants were those causing homocystinuria (1.12% risk allele frequency), and Stargardt disease (2.07%). The majority (85%) of Qatari SGD pathogenic variants were not present in Western populations such as European American, South Asian American, and African American in New York City and European and Afro-Caribbean in Puerto Rico; and only 50% were observed in a broad collection of data across the Greater Middle East including Kuwait, Iran, and United Arab Emirates. This study demonstrates the feasibility of developing accurate screening tools to identify SGD risk variants in understudied populations, and the need for ancestry-specific SGD screening tools. 2022, The Author(s).This is a collaborative work between Qatar Genome, Qatar Biobank, Weill Cornell (New York and Qatar), Hamad Medical Corporation and Sidra Medicine. We are thankful for everyone who contributed to this endeavor from all participating institutes. We would like to especially thank all participants in this study for their continuous support. We thank Dr. Fatemeh Abbaszadeh, for quality control and implementing QChip in the diagnostic services; N. Mohamed for editorial support, E. Betancourt for administrative support, E. Guzman for IT support, and J. Pillardy for high-performance computing support. J.R.F. also thanks Alan R. Shuldiner and Regeneron Genetics Center for supporting, J.R.F. to help complete this project. Special thanks to Alphonse Tharangeval at the Dasman Diabetes Institute in Kuwait for providing allele frequency lookups, and to the Center for Arab Genetic Studies in UAE, the GME Variome at University of California at San Diego and the Iranomefor providing public access to their databases. The authors are saddened by the passing of Andrew Brooks after the manuscript was submitted to the journal for review. This publication was made possible by The Qatar Foundation, the Weill Cornell Medical College in Qatar; NPRP 09-741-3 193, NPRP 5-436-3-116, NPRP 7-1425-3-370, NPRP 7-1301-3-336, and NPRP P8-1913-3-396 from the Qatar National Research Fund (a member of the Qatar Foundation). The findings achieved herein are solely the responsibility of the authors.Scopu