CAR-T-cells on the conveyor
A quick and easy way to obtain therapeutic T cells is proposed
Maxim Chubik, PCR.news
One of the most significant achievements in the treatment of oncological diseases over the past decade has been the creation of CAR-T therapy. CAR-T lymphocytes carry a chimeric antigen receptor (CAR) specific to a specific tumor marker. Immunotherapy with CAR-T cells is one of the most effective methods of cancer therapy today. Some CAR-T cells have already been approved for use in the clinic, hundreds more have reached the final stage of clinical trials.
Nevertheless, the method has serious basic limitations — the duration, high cost and labor intensity of the production of modified cells. T-cells need to be obtained from the patient, modified to fight a specific form of cancer using a vector bearing a structure with a chimeric receptor, cleaned, tested and injected back to the patient. It usually takes at least two weeks to create CAR-T cells from native T cells for clinical use. For each specific case, it is necessary to create a new series of CAR-T lymphocytes, and the cost of each round of production is approximately half a million dollars.
In a new paper, scientists from the University of British Columbia and the University of Montreal (Canada) propose a method that significantly simplifies the production and reduces the time to obtain T cells ready for therapeutic use. In a series of experiments, the authors confirmed the possibility of a more cost-effective strategy: not to make CAR-T cells individually from patients' T-lymphocytes, but to produce these immune cells from stem cells. They also established a set of minimum necessary steps needed to effectively stimulate pluripotent stem cells (PSC) to produce T cells in vitro.
Traditionally, in the production of CAR-T cells, feeder cells, for example, embryonic fibroblast cells, are used to maintain an undifferentiated state and a high level of PSC proliferation. However, co-cultivation systems increase costs and are of little use for large-scale production. In the new work, the authors did not use feeding cells, which made it possible to significantly simplify the technology.
Cultivation without unnecessary components in the medium allowed researchers to study the effect of individual proteins on cell proliferation and differentiation. They found that the addition of two proteins — DLL4 and VCAM1 — to PSC during differentiation increases the efficiency of immune cell production by almost 80 times.
During the study, the authors introduced PSC (iPS11 line) into the wells of tablets with immobilized DLL4 and VCAM1 proteins. The DLL4 protein (delta-like protein 4), a ligand of the Notch 1 and Notch 4 receptors, is expressed by the thymic epithelium, regulates thymopoiesis and is necessary for the maturation of newly formed vessels. VCAM-1 (vascular cell adhesion molecule 1) is one of the key molecules of cellular adhesion of the vascular endothelium, which ensures the strong adhesion of leukocytes to the endothelium and participates in signal transmission.
DLL4 and VCAM1 synergistically activate the transmission of signals along the Notch path. This is a conservative intracellular signal transmission pathway that regulates interactions between neighboring cells. Notch promotes proliferative signaling during embryonic development and neurogenesis and, in particular, stimulates the proliferation of T-cell clones from a common lymphoid precursor. It is the mechanism of forcing the transmission of signals along the Notch pathway under the combined influence of DLL4 and VCAM1 that the authors consider decisive in improving the differentiation of T cells from PSC.
The authors believe that by working with stimulating proteins instead of animal serum and feeding cells, it is possible to make a carefully controlled conveyor from the production process of obtaining T cells, which is easy to reproduce in any modern laboratory.
The article by Michaels et al. DLL4 and VCAM1 enhance the emergence of T cell–competent hematopoietic progenitors from human pluripotent stem cells is published in the journal Science Advances.
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