Efficient encapsulation of proteins within liposomes for slow release in vivo.

A highly efficient method for the liposome encapsulation of granulocyte colony stimulating factor (rhG-CSF) was developed. The method was found to be gentle and led to no protein aggregation, denaturation or loss of protein activity. The liposomes obtained were judged to be oligolamellar based on a comparison of the actual with the theoretical trapped volumes. Slow release of encapsulated material from the liposomes was demonstrated both in vitro (90% serum, 37 degrees C) and in vivo after subcutaneous injection.