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In this work affinity membrane adsorbers were investigated for the chromatographic purification of recombinant human erythropoietin (rhEPO) produced in mammalian cells. Cibacron Blue (CB), IDA-Cu +2 , wheat germ agglutinin (WGA), concanavalin A (ConA) and an anti-EPO monoclonal antibody (MAb) were tested as affinity ligands, attached to microporous Sartobind  membranes. In experiments carried out with cell culture supernatant, the best results were obtained with Sartobind-CB, Sartobind-WGA and Sartobind-MAb membranes. The thermodynamic parameters were determined by adsorption isotherms of rhEPO onto the membranes. Sartobind-ConA presented the lowest affinity for rhEPO, as evidenced by a lower association constant. For Sartobind-CB, Sartobind-IDA-Cu +2 and Sartobind-MAb K A was in the order of 10 5 L mol −1 , whereas for Sartobind-WGA it was 10 6 L mol −1 . Sartobind-CB eluates were also investigated by RP-HPLC. The purity level achieved in this one-step purification strategy was 55%, indicating that the Sartobind-CB membrane is a promising affinity membrane for rhEPO purification.

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In the downstream processing of recombinant protein production, the reduction of unit operations required for product capture and purification, is of the utmost priority due to its cost diminishing effect. In this regard, target protein capture from cell suspensions in a fluidized bed of affinity particles with different sizes (expanded bed adsorption (EBA) with classified particles), presents an efficient tool since EBA may substitute cell disintegration, separation by centrifugation or filtration, and packed bed adsorption. However, as illustrated by experiments with the BSA/yeast cells system, the entire broth processing used in EBA also has detrimental influences due to the cell (or cell debris) binding on the affinity carrier. In particular, external mass transfer may become more dominant, and the lifetime of the affinity particles may reduce as a result of other cleaning procedures. Using simulations performed with a commercial software package, the cost superiority of alternate process routes (EBA or packed bed adsorption with preceding steps) can be evaluated. This elucidates the favorable application range for each route.

In the present work, rhEPO was purified from crude CHO cell culture supernatant either with Sartobind-Cibacron Blue (CB) or Sartobind-IDA-Cu +2 affinity membranes. Purity degrees were of 55 and 75%, respectively.