Researchers at Areta International, an Italian contract manufacturing organization, have used multi-tray bioreactors under
good manufacturing practice (GMP) conditions to manufacture human T-lymphocytes (TALL-104 cell line) on a large scale for
cell therapy. TALL-104 cells are human, IL-2 dependent cells derived from T cytotoxic lymphocytes. They are tumoricidal and
not restricted by the major histocompatibility complex (MHC). The cells were initially isolated from a patient with acute
lymphoblastoid leukemia. With the help of IL-2, they can be expanded and maintained in vitro.
A research group led by D. Santoli at the Wistar Institute in Philadelphia demonstrated that TALL-104 cells were able to control
both spontaneous and induced malignant tumoral growth and increased survival rates in different animal models.1 To carry out these studies, the Wistar group would require a commercial level of TALL-104 cell production to reach their
target volume of cells.
According to the research group at Areta, commercial production levels of TALL-104 cells means that a propagation system must
be able to guarantee cell expansions to a factor of at least 109 in a homogeneous system.2 Using a multi-tray system (Nunc Cell Factory, Thermo Fisher Scientific) consisting of 10 trays and a cell culture surface
area of 6320 cm2 , they achieved recovery of between 2.5 to 5 x 109 TALL cells, meeting the criteria for commercial-scale cell propagation.
Maria Luisa Nolli, PhD, Areta's CEO, said the multi-tray bioreactors were an efficient method for manufacturing for early-stage
clinical trials. "The speed of process development and low investment required to set up solid, standard operating procedures
that we could scale up directly from a cell culture flask enabled us to get materials manufactured in a timely and affordable
manner," she said. Members of the research team agreed. "The single-use, modular and sterile multi-tray bioreactor was a useful
new method for industrial production of human cells for Phase 1 and Phase 2 clinical trials of cell therapy," said one member.
"With this system, we were able to manufacture a high quality and reliable product in compliance with current good manufacturing
Another contract manufacturing operation that has used multi-tray disposable bioreactors is Rentschler Biotechnologie, the
company that originally developed the multi-tray bioreactor format. Scientists there used human embryonic kidney cells (HEK293)
and four multi-tray units comprising 40 tray units to develop a serum-free transient expression method for antibodies, as
well as a standardized antibody purification protocol.3 The adherent nature of the HEK cells enabled repeated harvests, which increased antibody yields. Two types of IgGs were
expressed in the HEK cells. For both types of antibodies, the researchers harvested the cells four different times after 3
to 4 days of growth. The volume used during production was 4 L per 40-tray bioreactor, which yielded a total harvest volume
of 64 L for each IgG. IgG yields reached 12 mg/L in these serum-free conditions. The final yields achieved in this serum-free
environment were 530 mg for one IgG type and 430 mg for the other IgG type (Table 1).
Table 1. Summary of the results obtained after large-scale transient expression of two different human IgGs. In each case,
four harvests were performed repeatedly after 3 to 4 days of cultivation. The expression level reached 2 mg/L in serum-free
culture conditions. The 1st IgG yielded 530 mg and the 2nd IgG, 430 mg.