A chromatographically purified human TGF-β1 fraction from virally inactivated platelet lysates

TGF-β1 exerts important physiological functions in osteogenesis and chondrogenesis and may be of therapeutic interest. The aim of this work was to develop a scalable purification process of TGF-β1 from virally inactivated human platelets.

Apheresis platelet concentrates (N=12) were solvent/detergent (S/D) treated (1% TnBP/1% Triton X-45; 31°C) and the resulting platelet lysates were clarified by oil extraction and centrifugation, then chromatographed on an anion-exchange DEAE-Sepharose Fast-Flow column equilibrated in a PBS buffer, pH 7.5. The column was washed to eliminate unbound proteins and the S/D agents. Bound proteins were eluted using a 1 M NaCl-PBS buffer pH 7.5 (DEAE-eluate). The content in TGF-β1, PDGF-AB, VEGF, IGF-1, EGF, and b-FGF was measured by ELISA. Proteins, lipids, and S/D agents were assessed. Protein profile was determined by SDS-PAGE under reduced or non-reduced conditions.

Most proteins, including albumin and immunoglobulins G, A, and M did not bind to the DEAE column as evidenced also by SDS-PAGE. Essentially all PDGF, VEGF, and IGF were in the breakthrough. The DEAE-eluate contained close to 60% of the TGF-β1 at a mean concentration of about 102 ng/ml, whereas EGF, b-FGF were at about 0.72 and 0.18 ng/ml, respectively. The content in TnBP and Triton X-45 was <2 ppm.

A fraction enriched in TGF-β1 can be prepared from virally inactivated human platelet lysates using an easily scale process. Its interest in regenerative medicine and cell therapy will be evaluated in further studies.