This is the joint position from the Human Tissue Authority (HTA), Human Fertilisation and Embryology Authority (HFEA) and Medicines and Healthcare products Regulatory Agency (MHRA).
The aim of regulating human embryonic stem cells (hESCs) is to ensure that the highest standards are met from their derivation in the laboratory through to their clinical application.
The HFEA is responsible for regulating the procurement of gametes and the associated processing involved in the creation of an embryo. The HFEA’s remit includes the use of embryos in the derivation of stem cell lines but does not extend to the regulation of these stem cell lines themselves.
The HTA under the Human Tissue (Quality and Safety for Human Application) Regulations 2007 (as amended) regulates the processing, storage and distribution of stem cell lines for human application.
During the cell line derivation process the embryo is dissociated and it is at this processing stage that the HTA regulatory remit begins and the HFEA’s regulatory remit ceases.
When the derived hESC cell line is fully characterised and cultured to ensure uniform characteristics, it is a condition of all HFEA research licences that the cell line is deposited in the UK Stem Cell Bank.
During the processing/derivation phase, stem cell lines do not come within medicines regulation. However, once Master Cell Banks have been created with a reasonable expectation of clinical utility in a medicinal product, they fall within the remit of the MHRA .
 A master stem cell bank can be defined as an aliquot of a single pool of cells which generally has been prepared from the selected cell clone under defined conditions, dispensed into multiple containers and stored under defined conditions. The MCB is used to derive all working cell banks.. Source: EudraLex Volume 4: EU guidelines for Good Manufacturing Practice for Medicinal Products for Human and Veterinary Use, Annex 2: Manufacture of Biological active substances and Medicinal Products for Human (revision 2).