Embryonic-like stem cells derived from postpartum placenta delivered after spotaneous labor emerging as universal prophylactic cancer vaccine

In the eighth decade of the last century extensive clinical delayed-type hypersensitivity (DTH) skin tests to an intradermal injection of a pharmaceutical allogeneic human Placenta Suspension (phPS) performed in obstetrical, gynecological and control group patients have shown positive reaction in 239 patients with clinical conditions having been as histopatrhological substratum, a hypoxia-induced adaptive/reactive epithelial cell proliferation, e.g. syncytiotrophoblastic cell hyperplasia, endometrial cell hyperplasia, or different gynecological cancers. Because the immune response against phPS has shown antigenc similarities between normal placental and endometrial hyperplastic cells and different kinds of cancer cells and because many cancers adopt an embryonic stem-like gene expression pattern, it is suggested that the profile of hypoxia-promoting placental and endometrial stem cell proliferation is more embryonic-like, and that the immune respose against phPS is expected to cross-react with tumor cells in vivo. In the process of persistent growth and accelerated oxygen consumption by hyperplastic cytotrophoblastic cells and neoplastic cells in a hypoxic microenvironment, a basic shift in energy metabolism is accompanied by appearance of heat shock proteins (HSPs), of fetal isoenzymes and of membrane glycoproteins (reappearance of oncofetal antigens, OFAs), which, as result of their overexpression/amplification may induce a host immunological response. Thus, it is assumed that phPS prepared from full-term human placentas delivered after a spontaneous labor comprises stem/progenitor cells reverted to a proliferative embryonic stem cell-like-state upon exposure to labor-inducing intrmittent placental hypoxia and that by expressing HSP/OFAs could immunize to generate immune response againjst a variety of antigens that are shared by different kinds of epithelial cancers. This immunological feature of phPS qualifies is as a vaccine-related product that may be used for a preventive cancer vaccine when mixed with a potent adjuvant (BCGVaccine) and given normal healthy individuals.