Brain mesenchymal stem cells: The other stem cells of the brain?

Table 1 Major positive and negative markers used for identifying bone marrow mesenchymal stem cells and pericytes

Markers	MSCs	Pericytes	EC	HSPCs	NSPCs
CD10	+[12]	+[12]
CD13	+[12]	+[12]
CD29	+[12]	+[12]		+[91]	+[92]
CD44	+[12]	+[12]		+[93]	+[92]
CD73	+[12]	+[12]	+[94]
CD90	+[12]	+[12]		+[95]	+[92,96]
CD105	+[12]	+[12]	+[97]
CD140B	+[12]	+[12]
CD146	+/low[12,90]	+[12]	+[98]
CD166	+[12]	+[12]		+[99]
NG2	+[12]	+[12]	-[11]	-[100]
Nestin	+[101,102]	+[72]			+[103]
CD14	-[12]	-[12]
CD31	-[12]	-[12]	+[104]
CD34	-[12]	-[12]	+[105]	+[105]
CD45	-[12]	-[12]
CD133	-[12]	-[12]	-[106]	+[107]	+[108]
CD117	-[12]	-[12]		+[109]	+[110]
CD144	-[12]	-[12]	+[111]
vWF	-[112]	-[113]	+[114]

In the absence of any universal and specific marker to define mesenchymal stem cells, their immunophenotyping relies on the use of combinations of both positive and negative markers. Note that MSCs profile may vary depending on the cell culture conditions[88], or with their in situ localization[89]. Expression of the cell surface antigens CD73, CD90, CD105 and non-expression of CD14, CD34, CD45 are useful criteria to define bone MSCs and pericytes. MSCs: Mesenchymal stem cells; EC: Endothelial cells; HSPCs: Hematopoietic stem and progenitor cells; NSPCs: Neural stem and progenitor cells.