Derivation of clinical-grade mesenchymal stromal cells from umbilical cord under chemically defined culture condition - platform for future clinical application

The use of animal serum in culture medium brings safety concerns and batch-to-batch variability, and thus may restrict the clinical use of ex vivo expanded mesenchymal stromal cells (MSCs). Clinically compliant MSCs should be developed in adherence to serum-free, xeno-free and chemically defined medium (S&XFM-CD). In this study, we develop a S&XFM-CD by replacing all serum components with synthetic alternatives for the derivation of clinical-grade umbilical cord-derived MSCs (UCMSCs). The critical aspects including characterization, safety concerns, potency and exogenous factors contamination risk of UCMSCs in S&XFM-CD are compared with serum-containing medium (SCM). UCMSCs in S&XFM-CD retain fibroblastic-like morphology and immunophenotype of MSCs, and exhibit superior clone efficiency, proliferation capacity, and osteogenic and chondrogenic differentiation potential compared with SCM. Moreover, UCMSCs in S&XFM-CD retain similar immunosuppressive potential, and exhibit superior secretion levels of bFGF, PDGF-BB and IGF-1 compared with SCM. In addition, UCMSCs in S&XFM-CD do not undergo transformation, preserve the normal karyotypes and genomic stability, and are less prone to senescence process after long-term in vitro culture, which conforms to the current guidance of international and national evaluation standard. The S&XFM-CD developed here may serve as a GMP-grade production platform of UCMSCs for future clinical application.

Mouse embryonic palatal mesenchymal cells maintain stemness through the PTEN-Akt-mTOR autophagic pathway

BACKGROUND

Both genetic and environmental factors are implicated in the pathogenesis of cleft palate. However, the molecular and cellular mechanisms that regulate the development of palatal shelves, which are composed of mesenchymal cells, have not yet been fully elucidated. This study aimed to determine the stemness and multilineage differentiation potential of mouse embryonic palatal mesenchyme (MEPM) cells in palatal shelves and to explore the underlying regulatory mechanism associated with cleft palate formation.

METHODS

Palatal shelves excised from mice models were cultured in vitro to ascertain whether MEPM are stem cells through immunofluorescence and flow cytometry. The osteogenic, adipogenic, and chondrogenic differentiation potential of MEPM cells were also determined to characterize MEPM stemness. In addition, the role of the PTEN-Akt-mTOR autophagic pathway was investigated using quantitative RT-PCR, Western blotting, and transmission electron microscopy.

RESULTS

MEPM cells in culture exhibited cell surface marker expression profiles similar to that of mouse bone marrow stem cells and exhibited positive staining for vimentin (mesodermal marker), nestin (ectodermal marker), PDGFRα, Efnb1, Osr2, and Meox2 (MEPM cells markers). In addition, exposure to PDGFA stimulated chemotaxis of MEPM cells. MEPM cells exhibited stronger potential for osteogenic differentiation as compared to that for adipogenic and chondrogenic differentiation. Undifferentiated MEPM cells displayed a high concentration of autophagosomes, which disappeared after differentiation (at passage four), indicating the involvement of PTEN-Akt-mTOR signaling.

CONCLUSIONS

Our findings suggest that MEPM cells are ectomesenchymal stem cells with a strong osteogenic differentiation potential and that maintenance of their stemness via PTEN/AKT/mTOR autophagic signaling prevents cleft palate development.

Serum and xeno-free, chemically defined, no-plate-coating-based culture system for mesenchymal stromal cells from the umbilical cord

OBJECTIVES

Umbilical cord mesenchymal stromal cells (UCMSCs) can be considered to become a new gold standard for MSC-based therapies. A serum and xeno-free, chemically defined and no-plate-coating-based culture system will greatly facilitate development of robust, clinically acceptable bioprocesses for reproducibly generating quality-assured UCMSCs.

MATERIALS AND METHODS

In this study, we report for the first time, such a serum-free, xeno-free, completely chemically defined and no-plate-coating-based culture system for the isolation and expansion of UCMSCs, whose biological characteristics were evaluated and compared with serum-containing medium (SCM) methods.

RESULTS

This culture system not only supported UCMSC primary cultures but also allowed for their expansion at low seeding density. Compared to SCM, UCMSCs in SFM exhibited (i) higher proliferative and colony-forming capacities; (ii) distinctly different morphologies; (iii) similar phenotype; (iv) similar pluripotency-associated marker expression; (v) superior osteogenic, but reduced adipogenic differentiation capacitities. In addition, UCMSCs cultured in SFM retained similar immunomodulatory properties to those in SCM.

CONCLUSIONS

Our findings demonstrate the feasibility of isolating and expanding UCMSCs in a completely serum-free, xeno-free, chemically defined and no-plate-coating-based culture system and represent an important step forward for development of robust, clinically acceptable bioprocesses for UCMSCs. Further, this provides a superior study platform for UCMSCs biology in a controlled environment.

Hematopoietic stem and progenitor cells can be enriched by implanting biomaterial into spatium intermusculare

Hematopoietic stem and progenitor cells (HSPCs) have been used successfully to treat patients with cancer and disorders of the blood and immune systems. In this study, we tried to enrich HSPCs by implanting biomaterials into the spatium intermusculare of mice hind limbs. Gelatine sponges were implanted into the spatium intermusculare of mice and then retrieved after 12 days. The presence of HSPCs in the migrating cells (MCs) was detected by phenotypically probing with CD34⁺Sca-1⁺ and functionally confirming the presence of using colony-forming cell assay and assessing the long-term reconstitution ability. The frequency of CD34⁺, Sca-1⁺, and CD34⁺Sca-1⁺ cells and colony formation unit in the MCs was much higher than that in the bone marrow (BM). Moreover, transplanted MCs were able to home to BM, muscle, and spleen, which induced an efficient long-term hematopoietic reconstitution in vivo. In addition, HSPCs within the MCs originated from the BM. Furthermore, the administration of G-CSF greatly reduced the time of implantation, and increased the number of MCs and frequency of HSPCs in the MCs. These data provide compelling evidence that HSPCs can be enriched by implanting biomaterial into spatium intermusculare. Implantation of biomaterial may be seen as the first step to a proof of their applicability to clinical practice in enriching HSPCs.

Activation of canonical wnt pathway promotes differentiation of mouse bone marrow-derived MSCs into type II alveolar epithelial cells, confers resistance to oxidative stress, and promotes their migration to injured lung tissue in vitro

The differentiation of mesenchymal stem cells (MSCs) into type II alveolar epithelial (AT II) cells in vivo and in vitro, is critical for reepithelization and recovery in acute lung injury (ALI), but the mechanisms responsible for differentiation are unclear. In the present study, we investigated the role of the canonical wnt pathway in the differentiation of mouse bone marrow-derived MSCs (mMSCs) into AT II cells. Using a modified co-culture system with murine lung epithelial-12 (MLE-12) cells and small airway growth media (SAGM) to efficiently drive mMSCs differentiation, we found that GSK 3β and β-catenin in the canonical wnt pathway were up-regulated during differentiation. The levels of surfactant protein (SP) C, SPB, and SPD, the specific markers of AT II cells, correspondingly increased in mMSCs when Wnt3a or LiCl was added to the co-culture system to activate wnt/β-catenin signaling. The expression of these factors was depressed to some extent by inhibiting the pathway with the addition of DKK 1. The differentiation rate of mMSCs also depends on their abilities to accumulate and survive in inflammatory tissue. Our results suggested that the activation of wnt/β-catenin signaling promoted mMSCs migration towards ALI mouse-derived lung tissue in a Transwell assay, and ameliorated the cell death and the reduction of Bcl-2/Bax induced by H(2) O(2), which simultaneously caused reduced GSK 3β and β-catenin in mMSCs. These data supports a potential mechanism for the differentiation of mMSCs into AT II cells involving canonical wnt pathway activation, which may be significant to their application in ALI.

Acidic pH conditions mimicking degenerative intervertebral discs impair the survival and biological behavior of human adipose-derived mesenchymal stem cells

This study was designed to examine the survival and biological behavior of adipose-derived mesenchymal stem cells (ADMSCs) under an intervertebral disc (IVD)-like acidic environment. Human ADMSCs isolated from two age groups were cultured under four different pH levels (pH 7.4, 7.1, 6.8 and 6.5) which mimicked the standard condition and the normal, mildly degenerated and severely degenerated IVD. Cell viability was measured by fluorescein isothiocyanate-Annexin-V/propidium iodide staining, and cell proliferation was measured by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay. The expression of aggrecan, collagen-I, collagen-II, matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase-3 (TIMP-3), p53 and caspase-3 at the mRNA level was examined by realtime quantitative polymerase chain reaction, and the expression of aggrecan, collagen-I, collagen-II, MMP-2 and TIMP-3 at the protein level was measured by enzyme-linked immunosorbent assay. Acidic pH inhibited the viability and proliferation, and the expression of aggrecan, collagen-I and collagen-II of ADMSCs from both age groups. ADMSCs harvested from young and mature donors exhibited similar responses to the acidic pH, although cells from young donors appeared less sensitive to the low pH levels. The results demonstrated that acidic pH in IVD may be an important deleterious factor for ADMSC-based IVD regeneration. ADMSCs harvested from young donors may be more suitable to be utilized for the implantation into degenerated IVD, and the implantations may be more effective at an early stage of IVD degeneration when the pH of matrix acidity is higher than 6.8.