Ultrastructural characteristics of human mesenchymal stromal (stem) cells derived from bone marrow and term placenta.
Human mesenchymal stromal (stem) cells (hMSCs) isolated from adult bone marrow (BM-hMSCs) as well as amnion (AM-hMSCs) and chorion (CM-hMSCs) term placenta leaves were studied by transmission electron microscopy (TEM) to investigate their ultrastructural basic phenotype. At flow cytometry, the isolated cells showed a homogeneous expression of markers commonly used to identify hMSCs, i.e., CD105, CD44, CD90, CD166, HLA-ABC positivities, and CD45, AC133, and HLA-DR negativities. However, TEM revealed subtle yet significant differences. BM-hMSCs had mesenchymal features with dilated cisternae of rough endoplasmic reticulum (rER) and peripheral collections of multiloculated clear blisters; this latter finding mostly representing complex foldings of the plasma membrane could be revelatory of the in situ cell arrangement in the niche microenvironment. Unlike BM-hMSCs, CM-hMSCs were more primitive and metabolically quiescent, their major features being the presence of rER stacks and large peripheral collections of unbound glycogen. AM-hMSCs showed a hybrid epithelial-mesenchymal ultrastructural phenotype; epithelial characters included non-intestinal-type surface microvilli, intracytoplasmic lumina lined with microvilli, and intercellular junctions; mesenchymal features included rER profiles, lipid droplets, and well-developed foci of contractile filaments with dense bodies. These features are consistent with the view that AM-hMSCs have a pluripotent potential. In conclusion, this study documents that ultrastructural differences exist among phenotypically similar hMSCs derived from human bone marrow and term placenta leaves; such differences could be revelatory of the hMSCs in vitro differentiation potential and may provide useful clues to attempt their in situ identification.
Pasquinelli
Gianandrea
G
Section of Clinical Pathology, Department of Experimental Pathology, University of Bologna, Bologna, Italy. gianandr.pasquinelli@unibo.it
Tazzari
Pierluigi
P
Ricci
Francesca
F
Vaselli
Cristiana
C
Buzzi
Marina
M
Conte
Roberto
R
Orrico
Catia
C
Foroni
Laura
L
Stella
Andrea
A
Alviano
Francesco
F
Bagnara
Gian Paolo
GP
Lucarelli
Enrico
E
D000328:Adult; D053687:Adult Stem Cells / Q000276:immunology / Q000648:ultrastructure*; D000650:Amnion / Q000648:ultrastructure; D015703:Antigens, CD / Q000032:analysis; D001854:Bone Marrow Cells / Q000276:immunology / Q000648:ultrastructure*; D002469:Cell Separation; D002478:Cells, Cultured; D002823:Chorion / Q000648:ultrastructure; D005260:Female; D005434:Flow Cytometry; D015234:HLA-A Antigens / Q000032:analysis; D006801:Humans; D016130:Immunophenotyping; D059630:Mesenchymal Stem Cells / Q000276:immunology / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D010641:Phenotype; D010920:Placenta / Q000166:cytology / Q000276:immunology / Q000648:ultrastructure*; D039904:Pluripotent Stem Cells / Q000276:immunology / Q000648:ultrastructure*; D017154:Stromal Cells / Q000648:ultrastructure
D015703:Antigens, CD; D015234:HLA-A Antigens