FERTUS: Generation of cultured red blood cells with enhanced therapeutic potential

Red blood cells can serve as carriers of therapeutic proteins, but broad application of such functionally enhanced red blood cells requires development of novel technologies. In FERTUS two academic and two commercial partners will join forces to generate these red blood cells. This newly established public-private partnership consists of Erasmus MC (Rotterdam, NL), Sanquin Research (Amsterdam, NL), PAN-Biotech GMBH (Aidenbach, DE) and Erytech Pharma SA (Lyon, FR).

FERTUS will generate fundamental knowledge and apply this to develop functionally enhanced red blood cells. The long-term aim is to improve delivery of therapeutic proteins to patients, for instance in oncology and enzyme replacement therapies. This is a potentially large market serving many patients suffering from a wide range of conditions.

FERTUS has two key objectives. Key objective 1 is to solve the problem of cost-effective production of cultured red blood cells. FERTUS will take advantage of recent developments in cell culture technology and adapt these to optimise expansion and terminal differentiation of red blood cells under completely controlled conditions. This is required to enable manufacturing of cultured red blood cells suitable for transfusion. Key objective 2 is to express therapeutic proteins at high levels while maintaining the normal biophysical characteristics of the red blood cells. This is important to minimise the number of enhanced red blood cells required for therapeutic use, and to ensure that the therapeutic proteins are released slowly after transfusion. To achieve this, FERTUS will apply CRISPR genome engineering technology.

In summary, FERTUS will:

1. develop culture conditions for cost-effective production of transfusion-quality red blood cells
2. transfer this technology for large scale production of red blood cells in bioreactors
3. apply genome engineering to produce red blood cells loaded with therapeutic proteins
4. deliver red blood cells loaded with therapeutic proteins with optimal biophysical properties

Key objectives 1 and 2. FERTUS has succeeded in bringing a fully defined serum-free medium to the market. It is sold by FERTUS partner PAN Biotech under license from FERTUS partner Sanquin Research. This medium can be used in large scale cultures in bioreactors to expand and differentiate primary and human immortalized erythroid progenitors. Key objective 3: FERTUS has generated vectors for expression of intracellular and secreted proteins in HEK393T and erythroid progenitor cells. Production of biologically active proteins was achieved using fully defined serumfree medium. Key objective 4 was not achieved during the course of the FERTUS project.