Table 4.

Prospects for Standardization

➢ Pre-Dilution Cell Count Enumeration of cells with automated cell counters. Eliminate viability testing for determining the number of cells for CFU plating Same aliquot used to perform cell counts should also be used to set-up the CFU assay

➢ Preparation of Working Cell Suspension Consensus on cell phenotype to be used to prepare working cell suspensions Define working cell concentrations specific for HPC(A), HPC(M), HPC(CB) Verification that an accurate dilution is made

➢ Medium Inoculation and Plating Transfer semi-solid medium into culture plates with syringe or positive displacement pipet Define cell number to be plated per cm2 for HPC(A), HPC(M), HPC(CB) Require same medium formulation with same cytokine cocktail Perform assay in triplicate Use same size tissue culture plates (e.g. 35 mm, 24-well plate)

➢ CFC Readout Require use of a high quality inverted microscope Define how to report colony results (i.e. total colonies) Use of an automated CFU counter

➢ Quality Control Linearity evaluation to determine when a CFU plate is overgrown Define criteria for when a CFU plate is overgrown Strategy for follow-up when a plate is overgrown