[Human placental tissue: a source of natural hematopoietic regulators]

In this paper, it has been shown that human placental tissular extracts are a potent source of natural haemopoietic growth factors. The colony-stimulating activities (CSA) recovered by extraction from washed placental pulp were active both on human and murine haemopoietic progenitors, from monocytic and granulocytic lineages. Crude tissular extracts contained CSA titers at least ten fold the titers usually found in placenta culture media. Placenta is the only human tissue easily available for the study of natural tissue-bound haemopoietic regulators. Extraction on an industrial scale, as proposed for the first time in this paper, should also benefit the identification and purification of new minor molecular classes of growth and maturation factors or inhibitors involved in human haemopoiesis.