Isolation,expansion and characterization of bone marrow-derived mesenchymal stromal cells in serum-free conditions

Bone marrow-derived mesenchymal stromal cells (BM-MSCs) heralded a new beginning for regenerative medicine and generated tremendous interest as the most promising source for therapeutic application. Most cell therapies require stringent regulatory compliance and prefer the use of serum-free media (SFM) or xeno-free media (XFM) for the MSC production process, starting from the isolation onwards. Here, we report on serum-free isolation and expansion of MSCs and compare them with cells grown in conventional fetal bovine serum (FBS)-containing media as a control. The isolation, proliferation and morphology analysis demonstrated significant differences between MSCs cultured in various SFM/XFM in addition to their difference with FBS controls. BD Mosaic? Mesenchymal Stem Cell Serum-Free media (BD-SFM) and Mesencult-XF (MSX) supported the isolation, sequential passaging, tri-lineage differentiation potential and acceptable surface marker expression profile of BM-MSCs. Further, MSCs cultured in SFM showed higher immune suppression and hypo-immunogenicity properties, making them an ideal candidate for allogeneic cell therapy. Although cells cultured in control media have a significantly higher proliferation rate, BM-MSCs cultured in BD-SFM or MSX media are the preferred choice to meet regulatory requirements as they do not contain bovine serum. While BM-MSCs cultured in BD-SFM and MSX media adhered to all MSC characteristics, in the case of few parameters, the performance of cells cultured in BD-SFM was superior to that of MSX media. Pre-clinical safety and efficiency studies are required before qualifying SFM or XFM media-derived MSCs for therapeutic applications.     

骨髓间充质干细胞无血清培养

为建立一种化学成分明确的、能用于体外扩增骨髓间充质干细胞的无血清培养基, 且骨髓间充质干细胞经无血清培养扩增后仍能保持其多向分化的潜能。采用密度梯度离心结合贴壁法从1月龄新西兰大白兔股骨中分离骨髓间充质干细胞, 比较在含10%胎牛血清的培养基(SCM)和自制的化学成分明确的无血清培养基(CDSFM)中骨髓间充质干细胞的形态、增殖能力, 以及扩增后的骨髓间充质干细胞的细胞周期、集落形成能力和成骨、成脂肪分化能力。经过10 d的培养, 骨髓间充质干细胞在自制的无血清培养基中扩增了50倍, 在含10%胎牛血清的培养基中扩增了40倍。在无血清和有血清培养基中扩增后的细胞中G0/G1期比例分别为(80.31%±0.6%)和(75.24%±4.0%), 两者无显著差异(P>0.05)。无血清培养扩增后的骨髓间充质干细胞集落形成率(12.7%±4.0%)低于有血清培养组(28.7%±4.2%), 两者比较差异显著(P<0.01)。经过无血清培养扩增的骨髓间充质干细胞在成骨、成脂肪诱导分化培养基中能够分化成成骨和脂肪细胞。自制的化学成分明确的无血清培养基能够在体外培养扩增骨髓间充质干细胞, 并且维持其干细胞特性, 可以用于细胞治疗以及生物医学研究。     

Xeno-free chondrogenesis of bone marrow mesenchymal stromal cells: towards clinical-grade chondrocyte production

Current cell-based cartilage therapies relay on articular cartilage-derived autologous chondrocytes as a cell source, which possesses disadvantages, such as, donor site morbidity and dedifferentiation of chondrocytes during in vitro expansion. Due to these and other limitations, novel cell sources and production strategies are needed. Bone marrow-derived mesenchymal stromal cells (BM-MSCs) are a fascinating alternative, but they are not spontaneously capable of producing hyaline cartilage-like repair tissue in vivo. In vitro pre-differentiation of BM-MSCs could be used to produce chondrocytes for clinical applications. However, clinically compatible defined and xeno-free differentiation protocol is lacking. Hence, this study aimed to develop such chondrogenic differentiation medium for human BM-MSCs. We assessed the feasibility of the medium using three human BM-MSCs donors and validated the method by comparing BM-MSCs to three other cell types holding potential for articular cartilage repair. The effectiveness of the method was compared to conventional serum-free and commercially available chondrogenic differentiation media. The results show that the defined xeno-free differentiation medium is at least as efficient as conventionally used serum-free chondrogenic medium and performed significantly better on all cell types tested compared to the commercially available chondrogenic medium.     

Impact of bone marrow-derived mesenchymal stromal cells on experimental xenogeneic graft-versus-host disease

Background aimsGraft-versus-host disease (GVHD) is a life-threatening complication of allogeneic hematopoietic cell transplantation caused by donor T cells reacting against host tissues. Previous studies have suggested that mesenchymal stromal cells (MSCs) could exert potent immunosuppressive effects.MethodsThe ability of human bone marrow derived MSCs to prevent xenogeneic GVHD in non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice and in NOD/SCID/interleukin-2Rγ(null) (NSG) mice transplanted with human peripheral blood mononuclear cells (PBMCs) was assessed.ResultsInjection of 200 × 10⁶ human PBMCs intraperitoneally (IP) into sub-lethally (3.0 Gy) irradiated NOD/SCID mice also given anti-asialo GM₁ antibodies IP 1 day prior and 8 days after transplantation induced lethal xenogeneic GVHD in all tested mice. Co-injection of 2 × 10⁶ MSCs IP on day 0 did not prevent lethal xenogeneic GVHD induced by injection of human PBMCs. Similarly, injection of 30 × 10⁶ human PBMCs IP into sub-lethally (2.5 Gy) irradiated NSG mice induced a lethal xenogeneic GVHD in all tested mice. Injection of 3 × 10⁶ MSCs IP on days 0, 7, 14 and 21 did not prevent lethal xenogeneic GVHD induced by injection of human PBMCs.ConclusionsInjection of MSCs did not prevent xenogeneic GVHD in these two humanized mice models.     

Animal serum-free culture conditions for isolation and expansion of multipotent mesenchymal stromal cells from human BM

BACKGROUND: Multipotent mesenchymal stromal cells (MSC) have become important tools in regenerative and transplantation medicine. Rapidly increasing numbers of patients are receiving in vitro-expanded MSC. Culture conditions typically include FSC because human serum does not fully support growth of human MSC in vitro (MSC(FCS)). Concerns regarding BSE, other infectious complications and host immune reactions have fueled investigation of alternative culture supplements. METHODS: As PDGF has long been identified as a growth factor for MSC, we tested media supplementation with platelet lysate for support of MSC proliferation. RESULTS: We found that primary cultures of BM-derived MSC can be established with animal serum-free media containing fresh frozen plasma and platelets (MSC(FFPP)). Moreover, MSC(FFPP) showed vigorous proliferation that was superior to classical culture conditions containing FCS. MSC(FFPP) morphology was equivalent to MSC(FCS), and MSC(FFPP) expressed CD73, CD90, CD105, CD106, CD146 and HLA-ABC while being negative for CD34, CD45 and surface HLA-DR, as expected. In addition to being phenotypically identical, MSC(FFPP) could efficiently differentiate into adipocytes and osteoblasts. In terms of immune regulatory properties, MSC(FFPP) were indistinguishable from MSC(FCS). Proliferation of PBMC induced by IL-2 in combination with OKT-3 or by PHA was inhibited in the presence of MSC(FFPP). DISCUSSION: Taken together, FCS can be replaced safely by FFPP in cultures of MSC for clinical purposes.     

Bone marrow stromal cells (bone marrow-derived multipotent mesenchymal stromal cells) for bone tissue engineering: basic science to clinical translation

Bone tissue engineering is a promising field of regenerative medicine in which cultured cells, scaffolds, and osteogenic inductive signals are used to regenerate bone. This technology has already been used in several clinical studies and its efficacy has been reported. In this review, we focus on bone marrow stromal cells, which are the most commonly used cell source for bone tissue engineering. The nature of the cells, suitable culture conditions for bone tissue engineering, and their potential therapeutic applications are reviewed with possible caveats. Furthermore, recent advances in bone marrow stromal cell biology are discussed with reference to clinical translation.     

Genetic stability of bone marrow-derived human mesenchymal stromal cells in the Quantum System

Background aimsThe Quantum® Cell Expansion System (Quantum; Terumo BCT, Inc, Lakewood, CO, USA) is a novel hollow fiber-based device that automates and closes the cell culture process, reducing labor intensive tasks such as manual cell culture feeding and harvesting. The manual cell selection and expansion processes for the production of clinical-scale quantities of bone marrow-derived human mesenchymal stromal cells (BM-hMSCs) have been successfully translated onto the Quantum platform previously. The formerly static, manual, in vitro process performed primarily on tissue culture polystyrene substrates may raise the question of whether BM-hMSCs cultured on a hollow fiber platform yields comparable cell quality.MethodsA rigorous battery of assays was used to determine the genetic stability of BM-hMSCs selected and produced with the Quantum. In this study, genetic stability was determined by assessing spectral karyotype, micronucleus formation and tumorigenicity to resolve chromosomal aberrations in the stem cell population. Cell phenotype, adherent growth kinetics and tri-lineage differentiation were also evaluated. HMSC bone marrow aspirates, obtained from three approved donors, were expanded in parallel using T225 culture flasks and the Quantum.ResultsBM-hMSCs harvested from the Quantum demonstrated immunophenotype, morphology and tri-lineage differentiation capacity characteristics consistent with the International Society of Cell Therapy standard for hMSCs. Cell populations showed no malignant neoplastic formation in athymic mice 60 days post-transplant, no clonal chromosomal aberrations were observed and no DNA damage was found as measured by micronucleus formation.ConclusionsQuantum-produced BM-hMSCs are of comparable quality and demonstrate analogous genetic stability to BM-hMSCs cultured on tissue culture polystyrene substrates.     

Chondrogenic differentiation of human bone marrow-derived mesenchymal stromal cells in a three-dimensional environment

Cell therapy combined with biomaterial scaffolds is used to treat cartilage defects. We hypothesized that chondrogenic differentiation bone marrow-derived mesenchymal stem cells (BM-MSCs) in three-dimensional biomaterial scaffolds would initiate cartilaginous matrix deposition and prepare the construct for cartilage regeneration in situ. The chondrogenic capability of human BM-MSCs was first verified in a pellet culture. The BM-MSCs were then either seeded onto a composite scaffold rhCo-PLA combining polylactide and collagen type II (C2) or type III (C3), or commercial collagen type I/III membrane (CG). The BM-MSCs were either cultured in a proliferation medium or chondrogenic culture medium. Adult human chondrocytes (ACs) served as controls. After 3, 14, and 28 days, the constructs were analyzed with quantitative polymerase chain reaction and confocal microscopy and sulfated glycosaminoglycans (GAGs) were measured. The differentiated BM-MSCs entered a hypertrophic state by Day 14 of culture. The ACs showed dedifferentiation with no expression of chondrogenic genes and low amount of GAG. The CG membrane induced the highest expression levels of hypertrophic genes. The two different collagen types in composite scaffolds yielded similar results. Regardless of the biomaterial scaffold, culturing BM-MSCs in chondrogenic differentiation medium resulted in chondrocyte hypertrophy. Thus, caution for cell fate is required when designing cell-biomaterial constructs for cartilage regeneration.     

Accelerated and safe expansion of human mesenchymal stromal cells in animal serum-free medium for transplantation and regenerative medicine

Human bone marrow mesenchymal stromal cells (hMSC) are currently investigated for a variety of therapeutic applications. However, most expansion protocols still use fetal calf serum (FCS) as growth factor supplement which is a potential source of undesired xenogeneic pathogens. We established an expansion protocol for hMSC based on the use of GMP-produced basic medium LP02 supplemented with 5% of platelet lysate (PL) obtained from human thrombocyte concentrates. Compared to FCS-supplemented culture conditions, we found a significant increase in both colony forming unit-fibroblast (CFU-F) as well as cumulative cell numbers after expansion. This accelerated growth is optimized by pooling of at least 10 thrombocyte concentrates. A minimal requirement is the use of 5% of PL with an optimal platelet concentration of 1.5 x 10(9)/ml, and centrifugation of thawed lysate at high speed. Cells expanded by this protocol meet all criteria for mesenchymal stromal cells (MSCs), e.g. plastic adherence, spindle-shaped morphology, surface marker expression, lack of hematopoietic markers, and differentiation capability into three mesenchymal lineages. MSC at passage 6 were cytogenetically normal and retained their immune-privileged potential by suppressing allogeneic reaction of T-cells. Additionally, gene expression profiles show increased mRNA levels of genes involved in cell cycle and DNA replication and downregulation of developmental and differentiation genes, supporting the observation of increased MSC-expansion in PL-supplemented medium. In summary, we have established a GMP-compatible protocol for safe and accelerated expansion of hMSC to be used in cell and tissue therapy.     

A highly standardized and characterized human platelet lysate for efficient and reproducible expansion of human bone marrow mesenchymal stromal cells

BackgroundHuman platelet lysate (hPL) represents a powerful alternative to fetal bovine serum (FBS) for human mesenchymal stromal cell (hMSC) expansion. However, the large variability in hPL sources and production protocols gives rise to discrepancies in product quality, characterization and poor batch-to-batch standardization.MethodshPL prepared with more than 200 donors (200+DhPL) or with five donors (5DhPL) were compared in terms of growth factor (GF) contents and biochemical analysis. A multiple protein assay and proteomic analysis were performed to further characterize 200+DhPL batches. We also compared the phenotypic and functional characteristics of bone marrow (BM)-hMSCs grown in 200+DhPL versus FBS+basic fibroblast growth factor (bFGF).ResultsBy contrast to 5DhPL, industrial 200+DhPL displayed a strong standardization of GF contents and biochemical characteristics. We identified specific plasmatic components and platelet-released factors as the most relevant markers for the evaluation of the standardization of hPL batches. We used a multiplex assay and proteomic analysis of 200+DhPL to establish a proteomic signature and demonstrated the robust standardization of batches. 200+DhPL was shown to improve and standardize BM-hMSC expansion compared with FBS+bFGF. The levels of expression of BM-hMSC membrane markers were found to be much more homogeneous between batches when cells were cultured in 200+DhPL. BM-hMSCs cultured in parallel under both conditions displayed similar adipogenic and osteogenic differentiation potential and immunosuppressive properties.ConclusionsWe report a standardization of hPL and the importance of such standardization for the efficient amplification of more homogeneous and reproducible cell therapy products.     

Hydroxyapatite/regenerated silk fibroin scaffold-enhanced osteoinductivity and osteoconductivity of bone marrow-derived mesenchymal stromal cells

A novel hydroxyapatite/regenerated silk fibroin scaffold was prepared and investigated for its potential to enhance both osteoinductivity and osteoconductivity of bone marrow-derived mesenchymal stromal cells in vitro. Approx. 12.4 ± 0.06 % (w/w) hydroxyapatite was deposited onto the scaffold, and cell viability and DNA content were significantly increased (18.5 ± 0.6 and 33 ± 1.2 %, respectively) compared with the hydroxyapatite scaffold after 14 days. Furthermore, alkaline phosphatase activity in the novel scaffold increased 41 ± 2.5 % after 14 days compared with the hydroxyapatite scaffold. The data indicate that this novel hydroxyapatite/regenerated silk fibroin scaffold has a positive effect on osteoinductivity and osteoconductivity, and may be useful for bone tissue engineering.     

Development of a rapid culture method to induce adipocyte differentiation of human bone marrow-derived mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) derived from bone marrow are multipotent stem cells that can regenerate mesenchymal tissues such as adipose, bone or muscle. It is thought that hMSCs can be utilized as a cell resource for tissue engineering and as human models to study cell differentiation mechanisms, such as adipogenesis, osteoblastogenesis and so on. Since it takes 2-3 weeks for hMSCs to differentiate into adipocytes using conventional culture methods, the development of methods to induce faster differentiation into adipocytes is required. In this study we optimized the culture conditions for adipocyte induction to achieve a shorter cultivation time for the induction of adipocyte differentiation in bone marrow-derived hMSCs. Briefly, we used a cocktail of dexamethasone, insulin, methylisobutylxanthine (DIM) plus a peroxisome proliferator-activated receptor γ agonist, rosiglitazone (DIMRo) as a new adipogenic differentiation medium. We successfully shortened the period of cultivation to 7-8 days from 2-3 weeks. We also found that rosiglitazone alone was unable to induce adipocyte differentiation from hMSCs in vitro. However, rosiglitazone appears to enhance hMSC adipogenesis in the presence of other hormones and/or compounds, such as DIM. Furthermore, the inhibitory activity of TGF-β1 on adipogenesis could be investigated using DIMRo-treated hMSCs. We conclude that our rapid new culture method is very useful in measuring the effect of molecules that affect adipogenesis in hMSCs.     

Activated T cells modulate immunosuppression by embryonic-and bone marrow-derived mesenchymal stromal cells through a feedback mechanism

Background aimsHuman embryonic stem cell (hESC)-derived mesenchymal stromal cells (MSC) (hESC-MSC) are an alternative source of MSC to bone marrow (BM)-derived MSC (BM-MSC), which are being investigated in clinical trials for their immunomodulatory potential. hESC-MSC have the advantage of being consistent because each batch can be generated from hESC under defined conditions. In contrast, BM-MSC have a limited proliferative capacity.MethodsThe ability to suppress the proliferation of anti-CD3/CD28-stimulated CD4 ⁺ T cells by hESC-MSC was compared with adult BM-MSC and neonatal foreskin fibroblast (Fb).ResultshESC-MSC suppress the proliferation of CD4 ⁺ T cells in both contact and transwell systems, although inhibition is less in the transwell system. hESC-MSC are approximately 2-fold less potent (67 cells/100 T cells) than BM-MSC and Fb (37 and 34 cells/100 T cells, respectively) at suppressing T-cell proliferation by 50% in a transwell [inhibitory concentration(IC)₅₀]. The anti-proliferative effect is not contact-dependent but requires the presence of factors such as interferon (IFN)-γ produced by activated T cells. IFN-γ induces the expression of indoleamine-2,3-dioxygenase (IDO) in hESC-MSC, BM-MSC and Fb, contributing to their immunosuppressive property.ConclusionsThe feedback loop between MSC or Fb and activated T cells may limit the immunosuppressive effects of MSC and Fb to sites containing ongoing immunologic or inflammatory responses where activated T cells induce the up-regulation of IDO and immunomodulatory properties of MSC and Fb. These data demonstrate that hESC-MSC may be evaluated further as an allogeneic cell source for therapeutic applications requiring immunosuppression.