Table 3.
Key considerations for the biodistribution study of induced pluripotent stem cell-derived cell therapy products
| Considerations | |
|---|---|
| Bioanalytical assay method | unit notation: “cells/μL biofluid or mg tissue” is recommended |
| instrument: ddPCR is recommended to mitigate matrix effects | |
| standard sample: cell lysate is recommended | |
| primer/probe design: sensitivity, selectivity, and specificity should be considered | |
| PCR conditions: master mix, spillover, annealing temperature/duration, number of cycles, primer/probe concentrations, PCR input, replicate assays | |
| DNA extraction: use of an external control gene is proposed to normalize DNA variability | |
| calibration curve: a single surrogate calibration curve can be employed to minimize the number of animals used; linear regression: r2 > 0.98 | |
| QC samples: at least four samples at each concentration with each matrix, concentration, and dilution | |
| accuracy: within ±35% (50% for QC sample at lower concentrations) | |
| precision: <35% (50% for QC sample at lower concentrations) | |
| sample preparation: homogenization of the entire tissue is recommended to quantify CTPs heterogeneously distributed in organs | |
| In vivo biodistribution | duration: lifetime of the animal |
| species: immunodeficient animals | |
| sex: both male and female (depending on the clinical application) | |
| number of animals: at least three animals to evaluate individual variability; consider the natural mortality during the study duration | |
| tissue: tissues with abundant blood flow, those vital for maintaining life, and the transplantation site | |
| time points: multiple time points to capture cellular kinetics | |
| units: “cells/μL biofluid,” “cells/mg tissue,” or “cells/tissue” can be reported |
Abbreviations are as follows: CV, coefficient of variation; CTPs, cell therapy products; PCR, polymerase chain reaction; QC, quality control; RE, relative error.