Pluripotent stem cells within the adipose stromal compartment, termed adipose-derived stromal cells (ASCs), have the potential to differentiate into a variety of cell lineages both in vitro and in vivo. Imaging with expression of exogenous or endogenous green fluorescent protein (GFP) reporters facilitates the detailed research on ASCs’ physiological behavior during differentiation in vivo. This study was aimed to confirm whether ASCs expressing GFP still could be induced to chondrogenesis, and to compare the expression of exogenous or endogenous GFP in ASCs during chondrogenic differentiation. ASCs were harvested from inguinal fat pads of normal nude mice or GFP transgenic mice. Monolayer cultures of ASCs from normal mice were passaged three times and then infected with replication-incompetent adenoviral vectors carrying GFP genes. Allowed to recover for 5 days, Ad/GFP infected ASCs were transferred to chondrogenic medium as well as the ASCs from transgenic mice cultured in vitro over the same passages. The level of GFP in transgenic ASCs maintained stable till 3 months after chondrogenic induction. Whereas, high level of GFP expression in Ad/GFP infected ASCs could last for only 8 weeks and then declined stepwise. Important cartilaginous molecules such as SOX9, collagen type I, collagen type II, aggrecan, collagen type X were assessed using immunocytochemistry, RT-PCR, andWestern Blot. The results indicated that no matter the GFP was exogenous or endogenous, it did not influence the chondrogenic potential of ASCs in comparison with the normal controls. Moreover, chondrogenic lineages from ASCs also underwent phenotypic modulation called dedifferentiation as a result of long-term culture in monolayers similar to normal chondrocytes. (Mol Cell Biochem 277: 181–190, 2005)

This study was to determine the ectopic osteogenic ability of BMSCs in combination with a scaffolding material comprising hydroxyapatite and β-tricalcium phosphate matrix (HA/β-TCP). BMSCs were obtained from the SD rats and induced to osteogenesis. Then these induced cells were seeded into HA/β-TCP and the constructs were auto-implanted subcutaneously for up to 12 weeks. Histological analysis, immunostaing, RT-PCR and transmission electron microscopy of the retrieved specimens at various intervals showed obvious trends of ectopic bone formation with obvious alteration of cellular phenotype.

tomesenchymal cells in the first branchial arch were enzymatically isolated from the mandibular processes of BALB/c mice and were maintained in an intact state in a medium containing leukaemia inhibitory factor. Here, we first evaluated the proliferative activity of the cells after the third passage, using bromodeoxyuridine labelling and in situ hybridization of telomerase mRNA. Positive staining for expression of HNK-1, S-100 and vimentin confirmed that the population of stem cells originated from the ectomesenchyme, which did not express cytokeratin. Then we investigated the molecular and cellular characteristics of the ectomesenchymal cells during their differentiation towards neurogenic, endothelial, myogenic and odontogenic lineages. Expression of multiple lineagespecific genes and proteins was detected by utilizing a range of molecular and biochemical approaches when the cells were transferred to inductive medium. Histological and immunohistochemical analysis of the induced cells at various intervals indicated obvious phenotypic alteration and presence of specific proteins for the differentiated lineages, for example nestin, factor VIII, α-SMA and dentin sialophosphoprotein (DSPP), respectively. Correlatively, results of reverse transcription–PCR corroborated at Mrna level the expression of the characteristic molecules during differentiation. Therefore, it is suggested that the ectomesenchymal cells derived from the first branchial arch may represent a novel source of multipotential stem cells capable of undergoing expansion and variant differentiation in vitro.