Human liquid bone marrow culture in serum-free medium.

Prolonged in vitro maintenance of human bone marrow progenitor cells was achieved using a serum-free (SF) liquid culture system. Culture medium was based on Iscove's medium supplemented with bovine serum albumin, human transferrin, bovine insulin, soybean lecithin, cholesterol, hydrocortisone and alpha-thioglycerol. Under these standardized culture conditions, CFU-GM were maintained for up to 4 weeks, as is the case when using conventional serum-dependent medium. Erythropoiesis exhibited a slower decline than that found using serum containing medium. Development of normal haematopoiesis was effective in spite of poor stromal cell development--a confluent adherent layer as classically described in serum conditions was never achieved. Our newly defined system provides a reliable technique for studying human haematopoietic stem cell proliferation and differentiation in vitro; it allows for rational utilization of currently available purified recombinant growth factors. It may be a promising tool in the clinical use of cultured haematopoietic stem cells.