Hiroe Ohnishi

Induction of Pluripotent Stem Cells from Human Third Molar Mesenchymal Stromal Cells

The expression of four transcription factors (OCT3/4, SOX2, KLF4, and MYC) can reprogram mouse as well as human somatic cells to induced pluripotent stem (iPS) cells. We generated iPS cells from mesenchymal stromal cells (MSCs) derived from human third molars (wisdom teeth) by retroviral transduction of OCT3/4, SOX2, and KLF4 without MYC, which is considered as oncogene. Interestingly, some of the clonally expanded MSCs could be used for iPS cell generation with 30–100-fold higher efficiency when compared with that of other clonally expanded MSCs and human dermal fibroblasts. Global gene expression profiles demonstrated some up-regulated genes regarding DNA repair/histone conformational change in the efficient clones, suggesting that the processes of chromatin remodeling have important roles in the cascade of iPS cells generation. The generated iPS cells resembled human embryonic stem (ES) cells in many aspects, including morphology, ES marker expression, global gene expression, epigenetic states, and the ability to differentiate into the three germ layers in vitro and in vivo. Because human third molars are discarded as clinical waste, our data indicate that clonally expanded MSCs derived from human third molars are a valuable cell source for the generation of iPS cells.

Non-neuronal acetylcholine as an endogenous regulator of proliferation and differentiation of Lgr5-positive stem cells in mice

Non‐neuronal acetylcholine (ACh) is predicted to function as a local cell signaling molecule. However, the physiological significance of the synthesis of non‐neuronal ACh in the intestine remains unclear. Here, experiments using crypt–villus organoids that lack nerve and immune cells in culture led us to suggest that endogenous ACh is synthesized in the intestinal epithelium to evoke growth and differentiation of the organoids through activation of muscarinic ACh receptors (mAChRs). The extracts of the cultured organoids showed a noticeable capacity for ACh synthesis that was sensitive to a potent inhibitor of choline acetyltransferase. Imaging MS revealed endogenous ACh localized in the epithelial layer in mouse small intestinal epithelium in vivo, suggesting that there are non‐neuronal resources of ACh. Treatment of organoids with carbachol downregulated the growth of organoids and the expression of marker genes for epithelial cells. On the other hand, antagonists for mAChRs enhanced the growth and differentiation of organoids, indicating the involvement of mAChRs in regulating the proliferation and differentiation of Lgr5‐positive stem cells. Collectively, our data provide evidence that endogenous ACh released from intestinal epithelium maintains homeostasis of intestinal epithelial cell growth and differentiation via mAChRs in mice.

A comparative study of induced pluripotent stem cells generated from frozen, stocked bone marrow- and adipose tissue-derived mesenchymal stem cells

Bone marrow‐derived mesenchymal stem cells (BMSCs) and adipose tissue‐derived mesenchymal stem cells (AMSCs) have been used clinically for tissue regeneration; however, their proliferation/differentiation potentials are limited. Recently, induced pluripotent stem cells (iPSCs), known to have nearly unlimited potential to proliferate and differentiate into cells of all three germ layers, have gained wide interest in regenerative medicine. Here, we generated iPSCs from frozen‐stocked AMSCs and BMSCs and examined their biological characteristics by comparative analyses. Although the iPSCs were more challenging to generate from the BMSCs than the AMSCs, both iPSC populations expressed pluripotent markers, such as stage‐specific embryonic antigen (SSEA)‐3, SSEA‐4, tumour‐related antigens (TRAs) TRA‐1‐60 and TRA‐1‐81, OCT3/4 and NANOG. Furthermore, both cell populations differentiated well into three germ layer‐derived cells, both in vitro and in vivo. These results indicate that iPSCs derived from frozen AMSCs/BMSCs exhibit equally acceptable iPSC characteristics and have potential in clinical applications as an alternative source of autogenous stem cells. Copyright

Ex Vivo Expanded Allogeneic Mesenchymal Stem Cells With Bone Marrow Transplantation Improved Osteogenesis in Infants With Severe Hypophosphatasia.

Patients with severe hypophosphatasia (HPP) develop osteogenic impairment with extremely low alkaline phosphatase (ALP) activity, resulting in a fatal course during infancy. Mesenchymal stem cells (MSCs) differentiate into various mesenchymal lineages, including bone and cartilage. The efficacy of allogeneic hematopoietic stem cell transplantation for congenital skeletal and storage disorders is limited, and therefore we focused on MSCs for the treatment of HPP. To determine the effect of MSCs on osteogenesis, we performed multiple infusions of ex vivo expanded allogeneic MSCs for two patients with severe HPP who had undergone bone marrow transplantation (BMT) from asymptomatic relatives harboring the heterozygous mutation. There were improvements in not only bone mineralization but also muscle mass, respiratory function, and mental development, resulting in the patients being alive at the age of 3. After the infusion of MSCs, chimerism analysis of the mesenchymal cell fraction isolated from bone marrow in the patients demonstrated that donor-derived DNA sequences existed. Adverse events of BMT were tolerated, whereas those of MSC infusion did not occur. However, restoration of ALP activity was limited, and normal bony architecture could not be achieved. Our data suggest that multiple MSC infusions, following BMT, were effective and brought about clinical benefits for patients with lethal HPP. Allogeneic MSC-based therapy would be useful for patients with other congenital bone diseases and tissue disorders if the curative strategy to restore clinically normal features, including bony architecture, can be established.

Regulation of cell shape and adhesion by CD34.

We previously reported that expression of CD43/leukosialin induces cell rounding and microvillus formation via inhibition of cell adhesion. Here, we found that CD34, a cell surface sialomucin and marker for hematopoietic progenitor cells, also inhibited cell adhesion and induced cell rounding and microvillus formation. Forced expression of CD34-induced cell rounding, microvillus formation, and phosphorylation of ezrin/radixin/moesin (ERM) proteins in HEK293T cells, while inhibiting integrin-mediated cell re-attachment. Furthermore, CD34+ blood cells and KG-1 cells, which express endogenous CD34 on their surface, were spherical in shape, surrounded by microvilli, and non-adherent to substrata. In addition, cleavage of O-sialomucin augmented integrin-mediated cell adhesion of KG-1 cells. These results suggest the involvement of CD34 in the inhibition of integrin-mediated cell adhesion and formation of the cell surface structure. The inhibitory function of CD34 in cell adhesion may affect cell shape organization via phosphorylation of ERM proteins. Cellular structures such as the spherical shape and microvilli of CD34+ cells may also contribute to regulation of cell adhesion.

Formation of microvilli and phosphorylation of ERM family proteins by CD43, a potent inhibitor for cell adhesion: Cell detachment is a potential cue for ERM phosphorylation and organization of cell morphology

CD43/sialophorin/leukosialin, a common leukocyte antigen, is known as an inhibitor for cell adhesion. The ectodomain of CD43 is considered as a molecular barrier for cell adhesion, while the cytoplasmic domain has a binding site for Ezrin/Radixin/Moesin (ERM). We found expression of CD43 induced cell rounding, inhibition of cell re-attachment, augmentation of microvilli, and phosphorylation of ERM in HEK293T cells. Mutant studies revealed the ectodomain of CD43, but not the intracellular domain, essential and sufficient for all these phenomena. We also found that forced cell detachment by itself induced phosphorylation of ERM in HEK293T cells. Taken together, these findings indicate that inhibition of cell adhesion by the ectodomain of CD43 induces phosphorylation of ERM, microvilli formation, and eventual cell rounding. Furthermore, our study suggests a novel possibility that cell detachment itself induces activation of ERM and modification of cell shape.

Generation of Induced Pluripotent Stem Cells from Mesenchymal Stromal Cells Derived from Human Third Molars (Method)

Generation of induced pluripotent stem (iPS) cells have the potential for investigation of molecular mechanisms of disease, understanding the development of human tissues, and clinical applications. Although it was reported that various kinds of human somatic cells reprogrammed into iPS cells, most of them showed low reprogramming efficiency. Previously, we reported that clonally-expanded mesenchymal stromal/stem cells (MSCs) derived from tooth germs of human third molars efficiently reprogrammed into iPS cells by retroviral transduction of OCT3/4, SOX2, and KLF4 without c-MYC. Our data indicated that human third molars, which usually discarded as clinical wastes, are a valuable cell source for generation of iPS cells. Here, we describe detailed methods of the MSCs preparation and iPS cells generation from the MSCs.