<b>Multivariable Modelling of Cryopreserved PBMC Quality: A Real-World Prediction Tool Developed with ENDIA Data</b>

<p dir="ltr"><b>Background</b>Periheral blood mononuclear cells (PBMCs) are essential for immunological research, but post-thaw viability and recovery vary with pre-analytical factors. No validated tool currently predicts PBMC quality after thawing.</p><p dir="ltr"><b>Methods</b><br>We analysed 541 cryopreserved samples, including 316 experimentally collected PBMCs and 225 ENDIA biobank samples (PBMCs and CBMCs). Predictors included blood storage duration and temperature, storage viability, cell number per aliquot, number of aliquots, shipment method, biobanking duration, thawing site and sample type. Post-thaw viability and recovery were modelled using ordered beta regression (glmmTMB, R) and validated with an 80:20 train–test split. The ENDIA PBMC prediction tool implements these models as an R shiny application.</p><p dir="ltr"><b>Results</b>Post-thaw viability decreased with longer blood storage prior to PBMC/CBMC isolation (-5.31 % per day, 95% CI [-7.25, -3.37]), room temperature storage (–5.58%, [–9.99, –1.18]) and non-ENDIA thawing SOP (–11.50%, [–21.50, –1.51]). Post-thaw viability was positively associated with LN₂ shipment (21.10%, [13.81, 28.38]) and higher storage viability (0.26%, [0.10, 0.42]). Post-thaw recovery decreased with PBMC storage time (–0.54% per 100 days, [–0.95, –0.13]), blood storage (–5.75% per day [–8.28, –3.21], PBMC sample type (–18.18%, [–26.64, –9.73], and higher aliquot cell number (–0.64% per 1×10⁶, [–1.04, –0.24], but saw an increase when LN₂ shipping was used (24.76%, [18.27, 31.25]).</p><p dir="ltr"><b>Conclusion</b><br>The ENDIA PBMC post-thaw prediction tool (<a href="https://endia-pbmc-prediction-tool.shinyapps.io/app_folder/" target="_new">https://endia-pbmc-prediction-tool.shinyapps.io/app_folder/</a>) enables single or batch predictions with 95% CIs, interactive plots, and downloadable reports to support evidence-based sample selection and harmonised PBMC quality control across multicentre studies.</p>