Strong Immune Privileges of MSC and Other Nes-GFP⁺ Progenitors in Bone Marrow of Transgenic Mice

Immune privileges (IPs) have been demonstrated for several types of quiescent stem cells (SCs) in adult mammalian organisms. Cancer SCs (CSCs) also manifest IPs, which is one of the main concerns in cancer therapy. To elucidate the strength of non-pathological SCs IPs, we implanted bone marrow (BM) of transgenic N-GFPCF1 mice under the renal capsule of non-transgenic mice immunized with enhanced green fluorescent protein (GFP). We show that Nes-GFP⁺ mesenchymal SCs (MSCs) and other subpopulations of Nes-GFP⁺ progenitors in mouse BM have strong IPs, since they survive for at least six wk despite targetedly activated against them full immune system. We also demonstrate that MSCs retain their functionality after exposition to such immune pressure by successful retransplantation of the foci into the secondary non-immunized recipients. We suggest that nestin could be a marker for a wide spectrum of quiescent SCs with strong IPs, including CSCs.