Abstract
Several diseases are caused by the lack of functional proteins, including lysosomal storage diseases or haemophilia A and B. Patients suffering from one of these diseases are treated via enzyme replacement therapies to restore the missing protein. Although this treatment strategy prevents some disease symptoms, enzyme replacement therapies are very expensive and require very frequent infusions, which can cause infusion adverse reactions and massively impair the quality of life of the patients. This review proposes a technology to sustainably produce proteins within the patient to potentially make frequent protein-infusions redundant. This technology is based on blood circulating immune cells as producers of the needed therapeutic protein. To ensure a stable protein concentration over time the cells are equipped with a system, which induces cell proliferation when low therapeutic protein levels are detected and a system inhibiting cell proliferation when high therapeutic protein levels are detected.