Extracellular vesicles from tonsil­derived mesenchymal stromal cells show anti­tumor effect via miR­199a­3p.

Mesenchymal stem cells (MSCs) are mesoderm­originated adult SCs that possess multidirectional differentiation potential. MSCs migrate to injured tissue and secrete a range of paracrine factors that induce regeneration in damaged tissue and exert immune modulation. Because tumor progression is dependent on cross­talk between the tumor and its microenvironment, MSCs also produce extracellular vesicles (EVs) that mediate information transfer in the tumor microenvironment. However, the effect of MSC­derived EVs on tumor development and progression is still controversial. To date, tonsil­derived MSCs (T­MSCs) have been shown to possess all the defined characteristics of MSCs and show distinctive features of differential potential and immune modulation. To observe the effect of soluble mediators from T­MSCs on tumor growth, human liver cancer cell line (HepG2) cells were injected into nude mice and HepG2 cell scratch migration assay was performed using conditioned medium (CM) of T­MSCs. T­MSC CM inhibited tumor growth and progression and it was hypothesized that EVs from T­MSCs could inhibit tumor progression. microRNA (miRNA or miR) sequencing using five different origins of T­MSC­derived EVs was performed and highly expressed miRNAs, such as miR­199a­3p, miR­214­3p, miR­199a­5p and miR­199b­5p, were selected. T­MSCs inhibited tumor growth and HepG2 cell migration, potentially via miR­199a­3p targeting CD151, integrin α3 and 6 in HepG2 cells.

Mesenchymal Stem Cell-Derived Exosomes Protect Muscle Loss by miR-145-5p Activity Targeting Activin A Receptors.

Skeletal muscle mass is decreased under a wide range of pathologic conditions. In particular, chemotherapy is well known for inducing muscle loss and atrophy. Previous studies using tonsil-derived mesenchymal stem cells (T-MSCs) or a T-MSC-conditioned medium showed effective recovery of total body weight in the chemotherapy-preconditioned bone marrow transplantation mouse model. This study investigated whether extracellular vesicles of T-MSCs, such as exosomes, are a key player in the recovery of body weight and skeletal muscle mass in chemotherapy-treated mice. T-MSC exosomes transplantation significantly decreased loss of total body weight and muscle mass in the busulfan-cyclophosphamide conditioning regimen in BALB/c recipient mice containing elevated serum activin A. Additionally, T-MSC exosomes rescued impaired C2C12 cell differentiation in the presence of activin A in vitro. We found that T-MSC exosomes possess abundant miR-145-5p, which targets activin A receptors, ACVR2A, and ACVR1B. Indeed, T-MSC exosomes rescue muscle atrophy both in vivo and in vitro via miR-145-5p dependent manner. These results suggest that T-MSC exosomes have therapeutic potential to maintain or improve skeletal muscle mass in various activin A elevated pathologic conditions.

Tonsil-derived mesenchymal stem cells enhance allogeneic bone marrow engraftment via collagen IV degradation.

BACKGROUND: Co-transplantation of bone marrow cells (BMCs) and mesenchymal stem cells (MSCs) is used as a strategy to improve the outcomes of bone marrow transplantation. Tonsil-derived MSCs (TMSCs) are a promising source of MSCs for co-transplantation. Previous studies have shown that TMSCs or conditioned media from TMSCs (TMSC-CM) enhance BMC engraftment. However, the factors in TMSCs that promote better engraftment have not yet been identified. METHODS: Mice were subjected to a myeloablative regimen of busulfan and cyclophosphamide, and the mRNA expression in the bone marrow was analyzed using an extracellular matrix (ECM) and adhesion molecule-targeted polymerase chain reaction (PCR) array. Nano-liquid chromatography with tandem mass spectrometry, real-time quantitative PCR, western blots, and enzyme-linked immunosorbent assays were used to compare the expression levels of metalloproteinase 3 (MMP3) in MSCs derived from various tissues, including the tonsils, bone marrow, adipose tissue, and umbilical cord. Recipient mice were conditioned with busulfan and cyclophosphamide, and BMCs, either as a sole population or with control or MMP3-knockdown TMSCs, were co-transplanted into these mice. The effects of TMSC-expressed MMP3 were investigated. Additionally, Enzchek collagenase and Transwell migration assays were used to confirm that the collagenase activity of TMSC-expressed MMP3 enhanced BMC migration. RESULTS: Mice subjected to the myeloablative regimen exhibited increased mRNA expression of collagen type IV alpha 1/2 (Col4a1 and Col4a2). Among the various extracellular matrix-modulating proteins secreted by TMSCs, MMP3 was expressed at higher levels in TMSCs than in other MSCs. Mice co-transplanted with BMCs and control TMSCs exhibited a higher survival rate, weight recovery, and bone marrow cellularity compared with mice co-transplanted with BMCs and MMP3-knockdown TMSCs. Control TMSC-CM possessed higher collagenase activity against collagen IV than MMP3-knockdown TMSC-CM. TMSC-CM also accelerated BMC migration by degrading collagen IV in vitro. CONCLUSIONS: Collectively, these results indicate that TMSCs enhance BMC engraftment by the secretion of MMP3 for the modulation of the bone marrow extracellular matrix.

Verification of the role of exosomal microRNA in colorectal tumorigenesis using human colorectal cancer cell lines.

Exosomes are a group of small membranous vesicles that are shed into the extracellular environment by tumoral or non-tumoral cells and contribute to cellular communication by delivering micro RNAs (miRNAs). In this study, we aimed to evaluate the role of exosomal miRNAs from colorectal cancer cell lines in tumorigenesis, by affecting cancer-associated fibroblasts (CAFs), which are vital constituents of the tumor microenvironment. To analyze the effect of exosomal miRNA on the tumor microenvironment, migration of the monocytic cell line THP-1 was evaluated via Transwell migration assay using CAFs isolated from colon cancer patients. The migration assay was performed with CAFs ± CCL7-blocking antibody and CAFs that were treated with exosomes isolated from colon cancer cell lines. To identify the associated exosomal miRNAs, miRNA sequencing and quantitative reverse transcription polymerase chain reaction were performed. The migration assay revealed that THP-1 migration was decreased in CCL7-blocking antibody-expressing and exosome-treated CAFs. Colon cancer cell lines contained miRNA let-7d in secreted exosomes targeting the chemokine CCL7. Exosomes from colorectal cancer cell lines affected CCL7 secretion from CAFs, possibly via the miRNA let-7d, and interfered with the migration of CCR2+ monocytic THP-1 cells in vitro.

Co­transplantation of tonsil­derived mesenchymal stromal cells in bone marrow transplantation promotes thymus regeneration and T cell diversity following cytotoxic conditioning.

Bone marrow (BM) transplantation (BMT) represents a curative treatment for various hematological disorders. Prior to BMT, a large amount of the relevant anticancer drug needed to be administered to eliminate cancer cells. However, during this pre­BMT cytotoxic conditioning regimen, hematopoietic stem cells in the BM and thymic epithelial cells were also destroyed. The T cell receptor (TCR) recognizes diverse pathogen, tumor and environmental antigens, and confers immunological memory and self­tolerance. Delayed thymus reconstitution following pre­BMT cytotoxic conditioning impedes de novo thymopoiesis and limits T cell­mediated immunity. Several cytokines, such as RANK ligand, interleukin (IL)­7, IL­22 and stem cell factor, were recently reported to improve thymopoiesis and immune function following BMT. In the present study, it was found that the co­transplantation of tonsil­derived mesenchymal stromal cells (T­MSCs) with BM­derived cells (BMCs) accelerated the recovery of involuted thymuses in mice following partial pre­BMT conditioning with busulfan­cyclophosphamide treatment, possibly by inducing FMS­like tyrosine kinase 3 ligand (FLT3L) and fibroblast growth factor 7 (FGF7) production in T­MSCs. The co­transplantation of T­MSCs with BMCs also replenished the CD3+ cell population by inhibiting thymocyte apoptosis following pre­BMT cytotoxic conditioning. Furthermore, T­MSC co­transplantation improved the recovery of the TCR repertoire and led to increased thymus­generated T cell diversity.