Chondrogenic potential of human mesenchymal stem cells and expression of Slug transcription factor.

The scientific literature rarely reports experimental failures or inconsistent outcomes in the induction of cell differentiation; however, researchers commonly experience poor or unsuccessful responses to differentiating agents when culturing stem cells. One way of investigating the underlying reasons for such responses is to look at the basal expression levels of specific genes in multipotent stem cells before the induction of differentiation. In addition to shedding light on the complex properties of stem cells and the molecular modulation of differentiation pathways, this strategy can also lead to the development of important time- and money-saving tools that aid the efficient selection of cellular specimens - in this case, stem cells that are more prone to differentiate towards specific lineages and are therefore more suitable for cell-based therapeutic protocols in regenerative medicine. To address this latter aspect, this study focused on understanding the reasons why some human mesenchymal stem cell (hMSC) samples are less efficient at differentiating towards chondrogenesis. This study shows that analysis of the basal expression levels of Slug, a negative regulator of chondrogenesis in hMSC, provides a rapid and simple tool for distinguishing stem cell samples with the potential to form a cartilage-like matrix, and that are therefore suitable for cartilage tissue engineering. It is shown that high basal levels of Slug prevent the chondrogenic differentiation of hMSCs, even in the presence of transforming growth factor-β and elevated levels of Sox9

Study on Stem/Stromal Cells from Buccal Fat Pad and Subcutaneous Adipose Tissue for Periodontal and Oral Bone Regeneration In Vitro

Oral bone lost represents an important issue in maxillo-facial and dental surgery. In order to identify an easy tool in oral tissue engineering, we studied human adipose derived-stem/stromal cells from Bichat\u2019s fat pad (BFP-ASCs), compared to subcutaneous adipose tissue (SC-ASCs), and their interactions with oral tissues, scaffolds and a bioactive oral molecule (amelogenin). All the ASCs showed a high clonogenicity and the typical mesenchymal stem cells immunophenotype; additionally, when properly induced, osteogenic and adipogenic differentiation markers, such as ALP activity, collagen deposition and lipid vacuoles formation, become evident. Both BFP- and SC-ASCs adhered finely to bone, periodontal ligament, collagen membrane and polyglycol acid filaments and they maintained their osteodifferentiation potential in the presence of amelogenin. In particular, this enamel matrix protein seems to be an early osteoinductive factor for BFP-ASCs, whereas this effect is not manifested for SC-ASCs. Moreover, to improve a future cellular therapy eliminating the concerns about contact with animal proteins, we tested cells growth in the presence of autologous and heterologous serum (HAS and HHS, respectively). Interestingly, both ASCs adapted rapidly to HAS or HHS increasing their proliferation rates compared to standard culture condition. We conclude that ASCs are suitable in oral tissue engineering, and that BFP-ASCs, more accessible for dentists, are prone to respond to stimuli naturally secreted in the oral cavity; for this reason, we suggest them for future therapies of periodontal defects and oral bone regeneration

Frequent epigenetic inactivation of KIBRA, an upstream member of the Salvador/Warts/Hippo (SWH) tumor suppressor network, is associated with specific genetic event in B-cell acute lymphocytic leukemia

The WW-domain containing protein KIBRA has recently been identified as a new member of the Salvador/Warts/Hippo (SWH) pathway in Drosophila and is shown to act as a tumor suppressor gene in Drosophila. This pathway is conserved in humans and members of the pathway have been shown to act as tumor suppressor genes in mammalian systems. We determined the methylation status of the 5′ CpG island associated with the KIBRA gene in human cancers. In a large panel of cancer cell lines representing common epithelial cancers KIBRA was unmethylated. But in pediatric acute lymphocytic leukemia (ALL) cell lines KIBRA showed frequent hypermethylation and silencing of gene expression, which could be reversed by treatment with 5-aza-2′-deoxycytidine. In ALL patient samples KIBRA was methylated in 70% B-ALL but was methylated in <20% T-ALL leukemia (p = 0.0019). In B-ALL KIBRA methylation was associated with ETV6/RUNX1 [t(12;21) (p13;q22)] chromosomal translocation (p = 0.0082) phenotype, suggesting that KIBRA may play an important role in t(12;21) leukemogenesis. In ALL paired samples at diagnosis and remission KIBRA methylation was seen in diagnostic but not in any of the remission samples accompanied by loss of KIBRA expression in disease state compared to patients in remission. Hence KIBRA methylation occurs frequently in B-cell acute lymphocytic leukemia but not in epithelial cancers and is linked to specific genetic event in B-ALL