Characterization of mouse clonal mesenchymal stem cell lines established by subfractionation culturing method

Cellular Interactions in Cell Sheets Enhance Mesenchymal Stromal Cell Immunomodulatory Properties

Immune-related applications of mesenchymal stromal cells (MSCs) in cell therapy seek to exploit immunomodulatory paracrine signaling pathways to reduce inflammation. A key MSC therapeutic challenge is reducing patient outcome variabilities attributed to insufficient engraftment/retention of injected heterogenous MSCs. To address this, we propose directly transplantable human single-cell-derived clonal bone marrow MSC (hcBMSC) sheets. Cell sheet technology is a scaffold-free tissue engineering strategy enabling scalable production of highly engraftable cell constructs retaining endogenous cell-cell and cell-matrix interactions, important to cell function. cBMSCs, as unique MSC subset populations, facilitate rational selection of therapeutically relevant MSC clones from donors. Here, we combine human cBMSCs with cell sheet technology, demonstrating cell sheet fabrication as a method to significantly upregulate expression of immunomodulatory molecules interleukin (IL)-10, indoleamine 2,3-dioxygenase (IDO-1), and prostaglandin E synthase 2 (PTGES2) across GMP-grade hcBMSC lines and whole human bone marrow-derived MSCs compared to respective conventional cell suspensions. When treated with carbenoxolone, a gap junction inhibitor, cell sheets downregulate IL-10 and IDO-1 expression, implicating functional roles for intercellular sheet interactions. Beyond producing directly transferable multicellular hcBMSC constructs, cell sheet technology amplifies hcBMSC expression of immunomodulatory factors important to therapeutic action. In addition, this work demonstrates the importance of cell-cell interactions as a tissue engineering design criterion to enhance consistent MSC functions.

Phenotypic and Functional Characterizations of Mesenchymal Stem/Stromal Cells Isolated From Human Cranial Bone Marrow

Mesenchymal stem/stromal cells (MSCs) are adult stem cells that were originally isolated from bone marrow. In contrast to long bone-derived MSCs that have been extensively characterized, our knowledge regarding to MSCs isolated from flat bones (e.g., cranial bones) remain less clear. In this study, MSCs were purified from human cranial bone marrow (CB-MSCs) and their transdifferentiation capacity and immunomodulatory functions were further characterized. Phenotypic analysis of CB-MSCs demonstrated high expression of CD73, CD90, and CD105 while negative for CD14, CD34, and HLA-DR. Further in vitro differentiation assay shown that CB-MSCs capable of differentiating into cell types of mesenchymal origin (i.e., adipocytes, osetoblasts, and chondrocytes) and collectively, these results indicated that cells isolated from cranial bone marrow in this study are bona fide MSCs according to the minimal criteria proposed by the International Society for Cellular Therapy. Following in vitro expansion, single colony-derived CB-MSCs (scCB-MSCs) were obtained and confocal microscopy analysis further revealed functional heterogeneity within primary CB-MSCs. Specifically, obtained scCB-MSCs exhibited GABA progenitor features, as determined by olig2 and nestin. As expect, scCB-MSCs were readily induced to differentiate into GABAergic neuron-like cells. Furthermore, immunomodulatory roles of scCB-MSCs were evaluated following co-culture with human peripheral blood lymphocytes and results shown that co-culturing with scCB-MSCs significantly suppressed lymphocyte proliferation and promoted differentiation of lymphocytes into regulatory T cells but not Th1/Th17 phenotype. Overall, our results indicated that CB-MSCs exhibited clonal heterogeneity with marked propensity to differentiate into neural-like cells and this might represent promising candidates for the treatment of neurodegenerative diseases.

Dual effects of hypoxia on proliferation and osteogenic differentiation of mouse clonal mesenchymal stem cells

Mouse clonal mesenchymal stem cells (mc-MSCs) were cultured on a Cytodex 3 microcarrier in a spinner flask for a suspension culture under hypoxia condition to increase mass productivity. The hypoxia environment was established using 4.0 mM Na₂SO₃ with 10 μM or 100 µM CoCl₂ for 24 h in a low glucose DMEM medium. As a result, the proliferation of mc-MSCs under hypoxic conditions was 1.56 times faster than the control group over 7 days. The gene expression of HIF-1a and VEGFA increased 4.62 fold and 2.07 fold, respectively. Furthermore, the gene expression of ALP, RUNX2, COL1A, and osteocalcin increased significantly by 9.55, 1.55, 2.29, and 2.53 times, respectively. In contrast, the expression of adipogenic differentiation markers, such as PPAR-γ and FABP4, decreased. These results show that the hypoxia environment produced by these chemicals in a suspension culture increases the proliferation of mc-MSCs and promotes the osteogenic differentiation of mc-MSCs.

Culturing at Low Cell Density Delays Cellular Senescence of Human Bone Marrow-Derived Mesenchymal Stem Cells in Long-Term Cultures

Background and Objectives

Mesenchymal stem cells (MSCs) have immense therapeutic potential for treating intractable and immune diseases. They also have applications in regenerative medicine in which distinct treatments do not exist. Thus, MSCs are gaining attention as important raw materials in the field of cell therapy. Importantly, the number of MSCs in the bone marrow is limited and they are present only in small quantities. Therefore, mass production of MSCs through long-term culture is necessary to use them in cell therapy. However, MSCs undergo cellular senescence through repeated passages during mass production. In this study, we explored methods to prolong the limited lifetime of MSCs by culturing them with different seeding densities.

Methods and Results

We observed that in long-term cultures, low-density (LD, 50 cells/cm²) MSCs showed higher population doubling level, leading to greater fold increase, than high-density (HD, 4,000 cells/cm²) MSCs. LD-MSCs suppressed the expression of aging-related genes. We also showed that reactive oxygen species (ROS) were decreased in LD-MSCs compared to that in HD-MSCs. Further, proliferation potential increased when ROS were inhibited in HD-MSCs.

Conclusions

The results in this study suggest that MSC senescence can be delayed and that life span can be extended by controlling cell density in vitro. These results can be used as important data for the mass production of stem cell therapeutic products.

KLF10 is a modulatory factor of chondrocyte hypertrophy in developing skeleton

To define the functional role of Krüppel-like factor (KLF) 10 as a modulator of chondrocyte hypertrophy in developing skeleton, the developmental features in the long bone of KLF10 knockout (KO) mice were investigated and the mesenchymal stem cells (MSCs) from KLF10 KO mice were characterized regarding chondrogenesis and osteogenesis. Delayed long bone growth and delayed formation of primary ossification center were observed in an early embryonic stage in KLF10 KO mouse along with very low Indian hedgehog expression in epiphyseal plate. While the chondrogenic potential of mouse MSCs from KLF10 KO mice appeared normal or slight decreased, hypertrophy and osteogenesis were extensively suppressed. These findings suggest that KLF10 is a mediator of chondrocyte hypertrophy in developing skeleton, and that suppression of KLF10 may be employed as a new strategy for preventing hypertrophy in cartilage regeneration using MSCs.

Comparative characteristics of laryngeal-resident mesenchymal stromal cell populations isolated from distinct sites in the rat larynx

BACKGROUND

Although tissue-resident mesenchymal stromal cells (MSCs) in the larynx have been described, their distinct characteristics and roles have not been thoroughly explored. Therefore, we investigated stem cell characteristics and regenerative potentials of single clonal populations isolated from rat epiglottic mucosa (EM), lamina propria (LP), and macula flava (MF) to determine whether they comprised laryngeal tissue-resident stem cells.

METHODS

Single clonal laryngeal cells were isolated following microdissection of the EM, LP, and MF from the rat larynx. Several clonal populations from the three laryngeal subsites were selected and expanded in vitro. We compared the stem cell characteristics of self-renewal and differentiation potential, as well as the cell surface phenotypes and gene expression profiles, of laryngeal MSC-like cells to that of bone marrow MSCs (BM-MSCs). We also investigated the regenerative potential of the laryngeal cells in a radiation-induced laryngeal injury animal model.

RESULTS

Self-renewing, clonal cell populations were obtained from rat EM, LP, and MF. EM-derived and LP-derived clonal cells had fibroblast-like features, while MF-resident clonal cells had stellate cell morphology and lipid droplets containing vitamin A. All laryngeal clonal cell populations had MSC-like cell surface marker expression (CD29, CD44, CD73, and CD90) and the potential to differentiate into bone and cartilage cell lineages; EM-derived and MF-derived cells, but not LP-derived cells, were also able to differentiate into adipocytes. Clonal cells isolated from the laryngeal subsites exhibited differential extracellular matrix-related gene expression. We found that the mesenchymal and stellate cell-related genes desmin and nestin were enriched in laryngeal MSC-like cells relative to BM-MSCs (P < 0.001). Growth differentiation factor 3 (GDF3) and glial fibrillary acidic protein (GFAP) transcript and protein levels were higher in MF-derived cells than in other laryngeal populations (P < 0.001). At 4 weeks after transplantation, laryngeal MF-derived and EM-derived cells contributed to laryngeal epithelial and/or glandular regeneration in response to radiation injury.

CONCLUSIONS

These results suggest that cell populations with MSC characteristics reside in the EM, LP, and MF of the larynx. Laryngeal MSC-like cells contribute to regeneration of the larynx following injury; further investigation is needed to clarify the differential roles of the populations in laryngeal tissue regeneration, as well as the clinical implications for the treatment of laryngeal disease.

CTLA4-CD28 chimera gene modification of T cells enhances the therapeutic efficacy of donor lymphocyte infusion for hematological malignancy

Donor lymphocyte infusion (DLI) followed by hematopoietic stem cell transplantation has served as an effective prevention/treatment modality against the relapse of some hematologic tumors, such as chronic myeloid leukemia (CML). However, the therapeutic efficacies of DLI for other types of leukemia, including acute lymphocytic leukemia (ALL), have been limited thus far. Therefore, we examined whether increasing the reactivity of donor T cells by gene modification could enhance the therapeutic efficacy of DLI in a murine model of ALL. When a CTLA4-CD28 chimera gene (CTC28) in which the intracellular signaling domain of CTLA4 was replaced with the CD28 signaling domain was introduced into CD4 and CD8 T cells in DLI, the graft-versus-tumor (GVT) effect was significantly increased. This effect was correlated with an increased expansion of donor CD8 T cells in vivo, and the depletion of CD8 T cells abolished this effect. The CD8 T cell expansion and the enhanced GVT effect were dependent on the transduction of both CD4 and CD8 T cells with CTC28, which emphasizes the role of dual modification in this therapeutic effect. The CTC28-transduced T cells that expanded in vivo also exhibited enhanced functionality. Although the potentiation of the GVT effect mediated by the CTC28 gene modification of T cells was accompanied by an increase of graft-versus-host disease (GVHD), the GVHD was not lethal and was mitigated by treatment with IL-10 gene-modified third-party mesenchymal stem cells. Thus, the combined genetic modification of CD4 and CD8 donor T cells with CTC28 could be a promising strategy for enhancing the therapeutic efficacy of DLI.

Alginate Microcapsules Incorporating Hyaluronic Acid Recreate Closer in Vivo Environment for Mesenchymal Stem Cells

The potential clinical application of alginate cell microencapsulation has advanced enormously during the past decade. However, the 3D environment created by alginate beads does not mimic the natural extracellular matrix surrounding cells in vivo, responsible of cell survival and functionality. As one of the most frequent macromolecules present in the extracellular matrix is hyaluronic acid, we have formed hybrid beads with alginate and hyaluronic acid recreating a closer in vivo cell environment. Our results show that 1% alginate-0.25% hyaluronic acid microcapsules retain 1.5% alginate physicochemical properties. Moreover, mesenchymal stem cells encapsulated in these hybrid beads show enhanced viability therapeutic protein release and mesenchymal stem cells' potential to differentiate into chondrogenic lineage. Although future studies with additional proteins need to be done in order to approach even more the extracellular matrix features, we have shown that hyaluronic acid protects alginate encapsulated mesenchymal stem cells by providing a niche-like environment and remaining them competent as a sustainable drug delivery system.

ICOSL expression in human bone marrow-derived mesenchymal stem cells promotes induction of regulatory T cells

Mesenchymal stem cells (MSCs) can modulate lymphocyte proliferation and function. One of the immunomodulatory functions of MSCs involves CD4⁺CD25⁺FoxP3⁺ regulatory T cells (Tregs), which negatively regulate inflammatory responses. MSC-mediated Treg induction is supposed to be regulated by mechanisms requiring both soluble and cell contact-dependent factors. Although the involvement of soluble factors has been revealed, the contact-dependent mechanisms in MSC-mediated Treg induction remain unclear. We attempted to identify molecule(s) other than secreted factors that are responsible for MSC-mediated Treg induction and to uncover the underlying mechanisms. Under in vitro Treg-inducing conditions, ICOSL expression in MSCs coincided with Treg induction in co-cultures of MSCs with CD4⁺ T cells. When cultured in a transwell plate, MSCs failed to induce Tregs. Neutralization or knockdown of ICOSL significantly reduced Tregs and their IL-10 release. ICOSL overexpression in MSCs promoted induction of functional Tregs. ICOSL-ICOS signaling promoted Treg differentiation from CD4⁺ T cells through activation of the phosphoinositide 3-kinase-Akt pathway. MSCs primed with Interleukin-1β significantly induced Tregs through ICOSL upregulation. We demonstrated that the Treg-inducing activity of MSCs is proportionate to their basal ICOSL expression. This study provides evidence that ICOSL expression in human MSCs plays an important role in contact-dependent regulation of MSC-mediated Treg induction.

Immunodepletion and Hypoxia Preconditioning of Mouse Compact Bone Cells as a Novel Protocol to Isolate Highly Immunosuppressive Mesenchymal Stem Cells

Compact bones (CB) are major reservoirs of mouse mesenchymal stem cells (mMSC). Here, we established a protocol to isolate MSC from CB and tested their immunosuppressive potential. Collagenase type II digestion of BM-flushed CB from C57B/6 mice was performed to liberate mMSC precursors from bone surfaces to establish nondepleted mMSC. CB cells were also immunodepleted based on the expression of CD45 (leukocytes) and TER119 (erythroid cells) to eliminate hematopoietic cells. CD45^-TER119^- CB cells were subsequently used to generate depleted mMSC. CB nondepleted and depleted mMSC progenitors were cultured under hypoxic conditions to establish primary mMSC cultures. CB depleted mMSC compared to nondepleted mMSC showed greater cell numbers at subculturing and had increased functional ability to differentiate into adipocytes and osteoblasts. CB depleted mMSC had high purity and expressed key mMSC markers (>85% Sca-1, CD29, CD90) with no mature hematopoietic contaminating cells (<5% CD45, CD11b) when subcultured to passage 5 (P5). Nondepleted mMSC cultures, however, were less pure and heterogenous with <72% Sca-1⁺, CD29⁺, and CD90⁺ cells at early passages (P1 or P2), along with high percentages of contaminating CD11b⁺ (35.6%) and CD45⁺ (39.2%) cells that persisted in culture long term. Depleted and nondepleted mMSC nevertheless exhibited similar potency to suppress total (CD3⁺), CD4⁺ and CD8⁺ T cell proliferation, in a dendritic cell allostimulatory one-way mixed lymphocyte reaction. CB depleted mMSC, pretreated with proinflammatory cytokines IFN-γ, TNF-α, and IL-17A, showed superior suppression of CD8⁺ T cell, but not CD4⁺ T cell proliferation, relative to untreated-mMSC. In conclusion, CB depleted mMSC established under hypoxic conditions and treated with selective cytokines represent a novel source of potent immunosuppressive MSC. As these cells have enhanced immune modulatory function, they may represent a superior product for use in clinical allotransplantation.

Mesenchymal stromal cells inhibit CD25 expression via the mTOR pathway to potentiate T-cell suppression

Mesenchymal stromal cells (MSCs) are known to suppress T-cell activation and proliferation. Several studies have reported that MSCs suppress CD25 expression in T cells. However, the molecular mechanism underlying MSC-mediated suppression of CD25 expression has not been fully examined. Here, we investigated the mTOR pathway, which is involved in CD25 expression in T cells. We showed that MSCs inhibited CD25 expression, which was restored in the presence of an inducible nitric oxide synthase (iNOS) inhibitor. Since CD25 mRNA expression was not inhibited, we focused on determining whether MSCs modulated components of the mTOR pathway in T cells. MSCs increased the phosphorylation of liver kinase B1 (LKB1) and AMP-activated protein kinase (AMPK) and decreased the phosphorylation of ribosomal protein S6 kinase 1 (S6K1) and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1). In addition, the expression of 4E-BP1 increased dramatically in the presence of MSCs. An m⁷GTP pull-down assay showed increased binding of 4E-BP1 to the 5' cap-binding eukaryotic translation initiation factor 4E (eIF4E) complex in the presence of MSCs, which resulted in inhibition of mRNA translation. Treatment with 4EGI-1, a synthetic inhibitor of mRNA translation, also reduced CD25 expression in T cells. Polysome analysis confirmed decreased CD25 mRNA in the polysome-rich fraction in the presence of MSCs. Taken together, our results showed that nitric oxide, produced by MSCs, inhibits CD25 translation through regulation of the LKB1-AMPK-mTOR pathway to suppress T cells.

Single Cell Clones Purified from Human Parotid Glands Display Features of Multipotent Epitheliomesenchymal Stem Cells

A better understanding of the biology of tissue-resident stem cell populations is essential to development of therapeutic strategies for regeneration of damaged tissue. Here, we describe the isolation of glandular stem cells (GSCs) from a small biopsy specimen from human parotid glands. Single colony-forming unit-derived clonal cells were isolated through a modified subfractionation culture method, and their stem cell properties were examined. The isolated clonal cells exhibited both epithelial and mesenchymal stem cell (MSC)-like features, including differentiation potential and marker expression. The cells transiently displayed salivary progenitor phenotypes during salivary epithelial differentiation, suggesting that they may be putative multipotent GSCs rather than progenitor cells. Both epithelial and mesenchymal-expressing putative GSCs, LGR5⁺CD90⁺ cells, were found in vivo, mostly in inter-secretory units of human salivary glands. Following in vivo transplantation into irradiated salivary glands of mice, these cells were found to be engrafted around the secretory complexes, where they contributed to restoration of radiation-induced salivary hypofunction. These results showed that multipotent epitheliomesenchymal GSCs are present in glandular mesenchyme, and that isolation of homogenous GSC clones from human salivary glands may promote the precise understanding of biological function of bona fide GSCs, enabling their therapeutic application for salivary gland regeneration.

Characterization of adipose tissue mesenchymal stromal cell subsets with distinct plastic adherence

Mesenchymal stromal cells (MSCs) established by in-vitro adherence culture have been widely utilized for various cell therapeutic trials, but potential heterogeneity that can be caused by preparation methods are poorly characterized. In this study, we show that at least two distinct subsets of MSCs with different adherence to plastic surface exist in human adipose tissue-derived stromal vascular fraction (SVF); while 69% of total colony forming units in SVF adhere to the surface before 3 hrs of plating, 13-17% of colonogenic cells adhered to the surface at later period of 15 hr to 1 week after plating. Of note, the late adherent MSCs exhibited higher self-renewal of colony forming cells and higher proliferating potential with comparable level of osteogenic or adipogenic differentiation potential to the early adherence subsets. Moreover, late adherent cells exhibited distinct pattern of paracrine secretome including higher level secretion of cytokines than the early adherent subsets. Taken together, these results suggest the possibility that distinct adherence properties of MSCs can be another parameter of clonal heterogeneity in the subpopulations of adipose tissue MSCs and that it can be an important factor for optimization of MSC preparation for cell therapeutic trials.

Manufacture of Clinical-Grade Human Clonal Mesenchymal Stem Cell Products from Single Colony Forming Unit-Derived Colonies Based on the Subfractionation Culturing Method

Stem cell products derived from mesenchymal stem cells (MSCs) have been widely used in clinical trials, and a few products have been already commercialized. However, the therapeutic effects of clinical-grade MSCs are still controversial owing to mixed results from recent clinical trials. A potential solution to overcome this hurdle may be to use clonal stem cells as the starting cell material to increase the homogeneity of the final stem cell products. We have previously developed an alternative isolation and culture protocol for establishing a population of clonal MSCs (cMSCs) from single colony forming unit (CFU)-derived colonies. In this study, we established a good manufacturing practice (GMP)-compatible procedure for the clinical-grade production of human bone marrow-derived cMSCs based on the subfractionation culturing method. We optimized the culture procedures to expand and obtain a clonal population of final MSC products from single CFU-derived colonies in a GMP facility. The characterization results of the final cMSC products met our preset criteria. Animal toxicity tests were performed in a good laboratory practice facility, and showed no toxicity or tumor formation in vivo. These tests include single injection toxicity, multiple injection toxicity, biodistribution analysis, and tumorigenicity tests in vivo. No chromosomal abnormalities were detected by in situ karyotyping using oligo-fluorescence in situ hydridization (oligo-FISH), providing evidence of genetic stability of the clinical-grade cMSC products. The manufacture and quality control results indicated that our GMP methodology could produce sufficient clonal population of MSC products from a small amount of bone marrow aspirate to treat a number of patients.

Therapeutic effects of mouse bone marrow-derived clonal mesenchymal stem cells in a mouse model of inflammatory bowel disease

Mouse bone marrow-derived clonal mesenchymal stem cells (mcMSCs), which were originated from a single cell by a subfractionation culturing method, are recognized as new paradigm for stem cell therapy featured with its homogenous cell population. Next to proven therapeutic effects against pancreatitis, in the current study we demonstrated that mcMSCs showed significant therapeutic effects in dextran sulfate sodium (DSS)-induced experimental colitis model supported with anti-inflammatory and restorative activities. mcMSCs significantly reduced the disease activity index (DAI) score, including weight loss, stool consistency, and intestinal bleeding and significantly increased survival rates. The pathological scores were also significantly improved with mcMSC. We have demonstrated that especial mucosal regeneration activity accompanied with significantly lowered level of apoptosis as beneficiary actions of mcMSCs in UC models. The levels of inflammatory cytokines including TNF-α, IFN-γ, IL-1β, IL-6, and IL-17 were all significantly concurrent with significantly repressed NF-κB activation compared to the control group and significantly decreased infiltrations of responsible macrophage and neutrophil. Conclusively, our findings provide the rationale that mcMSCs are applicable as a potential source of cell-based therapy in inflammatory bowel diseases, especially contributing either to prevent relapse or to accelerate healing as solution to unmet medical needs in IBD therapy.

Murine embryonic fibroblast cell lines differentiate into three mesenchymal lineages to different extents: new models to investigate differentiation processes

Various diseases, injuries, and congenital abnormalities may result in degeneration and loss of organs and tissues. Recently, tissue engineering has offered new treatment options for these common, severe, and costly problems in human health care. Its application is often based on the usage of differentiated stem cells. However, despite intensive research and growing knowledge, many questions remain unresolved in the process of cell differentiation. The aim of this study was to find standardized cell models for analyzing molecular mechanisms of cell differentiation. We investigated the multipotency of three standardized murine embryonic fibroblast cell cultures using histological staining, western blotting, and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Our results demonstrated that NIH-3T3 and mouse embryonic fibroblast (MEF) cells were able to differentiate into adipogenic, chondrogenic, and osteogenic lineages expressing typical differentiation markers. Interestingly, Flp-In-3T3 cells did not differentiate into any of the three mesenchymal lineages, although this cell line is genetically closely related to NIH-3T3. The results were confirmed by histological staining. Flp-In-3T3, NIH-3T3, and MEF cells have usually been used for DNA transfections, recombinant protein expression, and as "feeder cells." Unlike mesenchymal stem cells (MSCs) and mesenchymal progenitor cells (MPCs), they are easy to obtain and to expand and are less prone to change their structure and morphology, even at higher passages. Our results suggest that Flp-In-3T3, MEF, and NIH-3T3 cells are highly suitable to be used as models to analyze molecular mechanisms of cell differentiation.

Bone marrow-derived clonal mesenchymal stem cells inhibit ovalbumin-induced atopic dermatitis

Mesenchymal stem cells (MSCs) possess immunomodulatory activities, including suppression of T- and B-cell activation. However, their effects on atopic dermatitis (AD) have not yet been studied. Using an ovalbumin-induced AD mouse model, we investigated whether MSCs can be used as therapeutics in AD. We isolated both allogeneic and syngeneic clonal MSCs (cMSCs) from mouse bone marrow according to the subfractionation culturing method. Our cMSCs suppressed both T- and B-cell activation. T-cell proliferation and cytokine production, including interferon (IFN)-γ and interleukin (IL)-4, were suppressed by inhibition of transcription factors, such as T-bet, GATA-3, and c-Maf. Those transcription factors were nitric oxide dependent. Immunoglobulin E (IgE) suppression occurred through downregulation of AID and BLIMP-1, important regulators for isotype class switch and B-cell differentiation. The cMSCs were injected intravenously into ovalbumin-induced AD mouse model, and the therapeutic effects were analyzed. Injection of both allogeneic and syngeneic cMSCs in an AD mouse model inhibited cell infiltration in skin lesions and decreased the serum level of IgE. IL-4 expression was also suppressed by cMSCs in both the lymph node and skin. The cMSCs migrated to skin lesions and draining lymph nodes. Taken together, these data demonstrated that cMSCs, which suppressed T- and B-cell functions, can be used for the treatment of AD in mice.

Intracavernous delivery of clonal mesenchymal stem cells restores erectile function in a mouse model of cavernous nerve injury

INTRODUCTION

Recently, much attention has focused on stem cell therapy; bone marrow-derived stem cells (BMSCs) are one of the most studied mesenchymal stem cells used in the field of erectile dysfunction (ED). However, a major limitation for the clinical application of stem cell therapy is the heterogeneous nature of the isolated cells, which may cause different treatment outcomes.

AIM

We investigated the effectiveness of mouse clonal BMSCs obtained from a single colony by using subfractionation culturing method (SCM) for erectile function in a mouse model of cavernous nerve injury (CNI).

METHODS

Twelve-week-old C57BL/6J mice were divided into four groups: sham operation group, bilateral CNI group receiving a single intracavernous (IC) injection of phosphate-buffered saline (20 μL) or clonal BMSCs (3 × 10(5) cells/20 μL), and receiving a single intraperitoneal (IP) injection of clonal BMSCs (3 × 10(5) cells/20 μL).

MAIN OUTCOME MEASURES

The clonal BMSC line was analyzed for cell-surface epitopes by using fluorescence-activated cell sorting and for differentiation potential. Two weeks after CNI and treatment, erectile function was measured by electrically stimulating the cavernous nerve. The penis was harvested for histologic examinations and Western blot analysis.

RESULTS

Clonal BMSCs expressed cell surface markers for mesenchymal stem cells and were capable of differentiating into several lineages, including adipogenic, osteogenic, and chondrogenic cells. Both IC and IP injections of clonal BMSCs significantly restored cavernous endothelial and smooth muscle content, and penile nNOS and neurofilament content in CNI mice. IC injection of clonal BMSCs induced significant recovery of erectile function, which reached 90-100% of the sham control values, whereas IP injection of clonal BMSCs partially restored erectile function.

CONCLUSION

We established a homogeneous population of mouse clonal BMSCs using SCM; clonal BMSCs successfully restored erectile function in CNI mice. The homogeneous nature of clonal mesenchymal stem cells may allow their clinical applications.

Mesenchymal Stem Cell Lines Isolated by Different Isolation Methods Show Variations in the Regulation of Graft-versus-host Disease

Since the discovery of the immunomodulation property of mesenchymal stem cells (MSCs) about a decade ago, it has been extensively investigated whether MSCs can be used for the treatment of immune-related diseases, such as graft-versus-host disease (GvHD). However, how to evaluate the efficacy of human MSCs for the clinical trial is still unclear. We used an MHC-mismatched model of GvHD (B6 into BALB/c). Surprisingly, the administration of the human MSCs (hMSCs) could reduce the GvHD-related mortality of the mouse recipients and xenogeneically inhibit mouse T-cell proliferation and IFN-γ production in vitro. We recently established a new protocol for the isolation of a homogeneous population of MSCs called subfractionation culturing methods (SCM), and established a library of clonal MSC lines. Therefore, we also investigated whether MSCs isolated by the conventional gradient centrifugation method (GCM) and SCM show different efficacy in vivo. Intriguingly, clonal hMSCs (hcMSCs) isolated by SCM showed better efficacy than hMSCs isolated by GCM. Based on these results, the MHC-mismatched model of GvHD may be useful for evaluating the efficacy of human MSCs before the clinical trial. The results of this study suggest that different MSC lines may show different efficacy in vivo and in vitro.

Discrimination between lung homeostatic and injury-induced epithelial progenitor subsets by cell-density properties

Stem/progenitor cells and their lineage derivatives are often identified by patterns and intensity of cell clusters of differentiation presentation. However, the cell biochemical façade can prove to be elusive, transient, and subject to interlaboratory disparities. To enhance current methods of lung stem cell isolation and identification and to investigate biophysical changes, which occur during homeostasis and in response to acute lung injury, we separated cells on a discontinuous density gradient, of 1.025-1.074 g/cm(3), and characterized the eluted lineages. At homeostasis, surfactant protein-C (SFTPC)-expressing cells of the alveolar type (AT)-2 lineage possessed average densities ≥1.039 g/cm(3) and aquaporin-5 producing AT1 cells equilibrated at densities <1.039 g/cm(3). While 0.74%±0.32% of lung cells were determined proliferating or postmitotic by BrdU nucleotide uptake, 73% of CD49f-, 72% of c-KIT-, and 61% of SCA-1-positive cells (putative alveolar progenitor lineage markers) showed densities ≤1.039 g/cm(3). CD49f/EpCAM(hi) progenitors, as well as c-KIT(pos)/CD45(neg) cells, could be enriched at the 1.039 g/cm(3) interface. Following acute bleomycin-induced injury, the frequency of BrdU-incorporating cells rose to 0.92%±0.36% and density could largely explain cell-lineage distribution. Specifically, a decline in the density of mitotic/postmitotic SFTPC-positive cells to ≤1.029 g/cm(3), in conjunction with an increase in CD45-positive, and proliferating CD45 and c-KIT cells in the heaviest fraction (≥1.074 g/cm(3)) were observed. These data attest to the generation of AT2 cells from low-density precursors and emphasize a relationship between cell density and molecular expression following injury, expanding on our current understanding of lung and progenitor cell dynamics.