The quality and safety of Advanced Therapy Medicinal Products (ATMPs) are contingent on that of their starting materials, particularly where these are substance of human origin such as mononuclear cells (MNCs) procured by apheresis. Across the UK there are over 50 Clinical Apheresis Units (CAUs) operating under a Human Tissue Authority (HTA) collecting starting material for ATMPs. The SAMPLE project brough together experts from across the country to produce recommendations for the procurement of starting materials for ATMP manufacture.