Ultrastructural Characteristics of Human Mesenchymal Stromal (Stem) Cells Derived from Bone Marrow and Term Placenta

Abstract

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.

Thoracic Aortas from Multiorgan Donors Are Suitable for Obtaining Resident Angiogenic Mesenchymal Stromal Cells

“…Again, ultrastructural investigation revealed a strict resemblance with MSCs. After culturing, these cells showed a multivacuolar appearance and a high synthetic competence, that is, prominence of rough endoplasmic reticulum, as we recently observed in MSCs derived from the human bone marrow [17].…”

“…Details are provided in the supplemental online material. As already described [17], cells were also collected in Eppendorf tubes immediately after detachment; pellets were processed for electron microscopy as described in the supplemental online material.…”

“…Reverse transcription reactions were performed in a 20-l volume with 2 g of total RNA using M-MLV Reverse Transcriptase (Invitrogen) following the manufacturer's protocol. Oligo(dT) [12][13][14][15][16][17][18] primers (Invitrogen) were used for first strand synthesis (details are provided in the supplemental online material). The expression of the following mRNAs was investigated: OCT4, BMI-1, BCRP-1, Interleukin-6 (IL6), c-kit, CD133, KDR, and ␤2 microglobulin (control).…”

Phenotypic Characterization and In Vivo Localization of Human Adipose-Derived Mesenchymal Stem Cells

“…The cells had a relatively high nuclear/ cytoplasm (N/C) ratio, prominent nucleoli, premature cytoplasmic organelles, and numerous filipodia. These characteristics are similar to those of bone marrow-derived mesenchymal stem cells (Pasquinelli et al, 2007). hADMSC morphology including cell size, shape, nuclear density, and cytoplasmic contents varied in this study.…”

Mitochondrial Function and Energy Metabolism in Umbilical Cord Blood- and Bone Marrow-Derived Mesenchymal Stem Cells

“…In addition, UCBMSCs showed more abundant rER than BMMSCs. In previous studies, no differences have been found in mitochondrial number or structure and, to our knowledge, this is the first time that the difference in mitochondrial-to-cytoplasm area ratio has been demonstrated between these hMSC types [42]. Since the mitochondrial-tocytoplasm area ratio also increased after 14-days osteoinduction in all hMSC types and the increase was most striking in BMMSC > 50, we believe that the higher mitochondrial-to-cytoplasm area ratio in UCBMSC and BMMSC < 18 compared with BMMSC > 50 could indicate different overall maturation levels of these cells.…”