Extracellular vesicles from mesenchymal stem cells of dental pulp and adipose tissue display distinct transcriptomic characteristics suggestive of potential therapeutic targets.

Objective: Mesenchymal stem cells (MSCs) are isolated from various human tissues and used for therapy, in which beneficial effects are attributed mainly to mesenchymal stem cell-derived extracellular vesicles (MSC-EVs). Whereas MSCs of diverse tissue types share cardinal stem cell features, it is becoming evident that MSCs of each tissue type possess unique properties as well. For designing efficient stem cellbased therapies, it is crucial to understand the unique properties associated with MSCs and MSC-EVs of each tissue type. Such unique properties can be analyzed through transcriptomic approaches using comprehensive gene expression databases and sophisticated analytical tools. Here, we comparatively studied the transcriptomes in MSC-EVs of dental pulp and adipose tissue. Additionally, the transcriptomes of MSC-EVs were compared with the cellular transcriptomes of MSCs for the same tissue types. Methods: MSCs were cultured from human dental pulp and adipose tissue specimens. Conditioned culture media were collected to prepare MSC-EVs, from which RNAs were isolated and subjected to next-generation sequencing for transcriptomic analysis. Gene expression signatures in MSC-EVs of each tissue type were investigated using gene set analysis. Results: MSC-EVs obtained from dental pulp-derived MSCs showed distinct transcriptomic signatures of neurogenesis and neural retina development while MSC-EVs of adipose tissue-derived MSCs showed signatures of mitochondrial activity and skeletal system development. The transcriptomes of MSC-EVs resembled the cellular transcriptomes of MSCs, and the genes associated with neurogenesis were highly expressed in both MSCs and MSC-EVs of dental pulp. Adipose tissue-derived MSCs and MSC-EVs highly expressed genes associated with angiogenesis, hair growth, and dermal matrices. Conclusion: The clear and distinct signatures of neurogenesis and neural retina development in dental pulp-derived MSC-EVs imply neurodegenerative disorders and retinal diseases as putative therapeutic targets. In contrast, the transcripts in adipose tissue-derived MSC-EVs could be useful in rejuvenating the skin and musculoskeletal system. Further insights into MSC-EVs of divergent tissue types may expand the list of potential therapeutic targets.

Comparative transcriptomic analysis of human mesenchymal stem cells derived from dental pulp and adipose tissues.

Objective: Mesenchymal stem cells (MSCs) have been isolated from various human tissues. Although they share cardinal stem cell features of self-renewal and multi-potency, they also seem to possess distinct characteristics depending on the tissue types they originated from. When developing stem cell-based therapies, MSCs with the most desirable characteristics should be chosen. However, our knowledge on tissue type-specific characteristics of MSCs is limited. Here, we comparatively studied the gene expression profiles of MSCs from different tissue types, and predicted target diseases suitable for each type of MSCs. Methods: We harvested MSCs from human dental pulp and adipose tissue specimens and subjected them to gene expression microarray analysis. Characteristic gene expression signatures of the MSCs from each tissue type were identified using gene-annotation enrichment analysis. Results: Dental pulp-derived MSCs exhibited gene expression signatures of neuronal growth, while adipose tissue-derived MSCs exhibited signatures of angiogenesis and hair growth. MSCs from each tissue type expressed a discrete set of genes encoding secretory peptides, which may function as paracrine factors. Conclusions: MSCs derived from different tissue types demonstrated distinct gene expression signatures, which are suggestive of target diseases in clinical applications of the MSCs and stem cell-conditioned media. By expanding the analysis to MSCs from a wide range of tissue types, and by employing multiple omics approaches, a catalogue of MSCs and therapeutic targets can be generated.

Ex vivo-expanded natural killer cells kill cancer cells more effectively than ex vivo-expanded γδ T cells or αß T cells.

Adoptive immunotherapy of cancer is evolving with the development of novel technologies for generating a large number of activated killer cells such as natural killer (NK) cells, γδ T cells, and αß T cells. We have recently established large-scale culture methods to generate activated NK cells from human peripheral blood, and demonstrated that expanded NK cells have higher cytotoxicity against cancer cells than freshly isolated NK cells. In this study, we compared cultured NK cells with cultured γδ T and αß T cells that were prepared by conventional culture methods regarding the expression of cytotoxic molecules and cytotoxicity against cancer cells. Natural cytotoxicity receptors such as NKp30, NKp44 and NKp46, and perforin were expressed most exclusively on NK cells. Granzyme A, NKG2D, and interferon-γ were dominantly expressed in NK cells and γδ T cells but not in αß T cells. Consistent with the expression profiles of the cytotoxic molecules, cultured NK cells from both healthy volunteers and cancer patients demonstrated significantly higher cytotoxicity against cancer cell lines, including MHC class I-positive cell lines, compared with cultured γδ T cells and cultured αß T cells. Additionally, NK cells, unlike γδ T cells or αß T cells, expressed high levels of CD16, and showed augmented cytotoxicity when co-administered with an anti-CD20 monoclonal antibody drug, rituximab. These results suggest the excellent efficacy of expanded NK cells for cancer treatment.