Ubiquitous expression of FSH/LH/hCG receptors, OCT-4, and CD133 in adult organs and cancers reflects novel VSELs biology

Very small embryonic-like stem cells (VSELs) were first reported in bone marrow and cord blood. We detected them by immunolocalization studies using polyclonal OCT-4 antibody on human testicular and ovarian cell smears. Cells with nuclear OCT-4A were the VSELs and cytoplasmic OCT-4 was expressed in the immediate descendants, i.e. spermatogonial stem cells and ovary germ stem cells. VSELs are postulated to be primordial germ cells, and during their migration to the gonadal ridge during embryonic development, they also migrate to various somatic organs, serve as a backup pool for tissue-specific adult stem cells to maintain life-long tissue homeostasis, and are also postulated to be the ‘embryonic remnants’ whose uncontrolled proliferation possibly results in cancer. VSELs express receptors for gonadotropin and sex hormones and express OCT-4, CD133, and hCG and thus their presence, differentiation, and uncontrolled proliferation during cancer could explain ubiquitous expression of OCT-4, CD133, hCG and receptors for sex and gonadotropin hormones in various normal and cancerous somatic and gonadal tissues.