Tumor necrosis factor-alpha and TNF-beta inhibit clonogenicity of mobilized human hematopoietic progenitors

Phenotypic characterization of regional human meniscus progenitor cells

Stimulating meniscus regeneration using meniscal progenitor cells has been suggested as a promising new strategy. However, there is a lack of studies which decisively identify and characterize progenitor cell populations in human meniscus tissues. In this study, donor-matched progenitor cells were isolated via selective fibronectin adhesion from the avascular and vascular regions of the meniscus and chondroprogenitors from articular cartilage (n = 5). The mixed populations of cells from these regions were obtained by standard isolation techniques for comparison. The colony formation efficacy of avascular progenitors, vascular progenitors and chondroprogenitors was monitored using Cell-IQ® live cell imaging. Proliferation rates of progenitors were compared with their mixed population counterparts. Cell surface markers indicative of mesenchymal stromal cells profile and progenitor markers were characterized by flow cytometry in all populations. The fibrochondrogenic capacity was assessed via fibrochondrogenic differentiation and measuring GAG/DNA content and morphology. All meniscal progenitor and chondroprogenitor populations showed superior colony forming efficacy and faster proliferation rates compare to their mixed populations. Progenitor populations showed significantly higher positivity for CD49b and CD49c compared to their mixed population counterparts and chondroprogenitors had a higher positivity level of CD166 compared to mixed chondrocytes. GAG/DNA analysis demonstrated that progenitor cells generally produced more GAG than mixed populations. Our study demonstrates that the human meniscus contains meniscal progenitor populations in both the avascular and vascular regions. Meniscal progenitors derived from the vascular region exhibit enhanced proliferative and fibrochondrogenic characteristics compared to those from the avascular region; this may associate with the enhanced meniscal healing potential in the vascular region. These findings build on the body of evidence which suggests that meniscal progenitors represent an attractive cell therapy strategy for meniscal regeneration.

Chronic lymphocytic leukemia B-cell-derived TNFα impairs bone marrow myelopoiesis

TNFα is implicated in chronic lymphocytic leukemia (CLL) immunosuppression and disease progression. TNFα is constitutively produced by CLL B cells and is a negative regulator of bone marrow (BM) myelopoiesis. Here, we show that co-culture of CLL B cells with purified normal human hematopoietic stem and progenitor cells (HSPCs) directly altered protein levels of the myeloid and erythroid cell fate determinants PU.1 and GATA-2 at the single-cell level within transitional HSPC subsets, mimicking ex vivo expression patterns. Physical separation of CLL cells from control HSPCs or neutralizing TNFα abrogated upregulation of PU.1, yet restoration of GATA-2 required TNFα neutralization, suggesting both cell contact and soluble-factor-mediated regulation. We further show that CLL patient BM myeloid progenitors are diminished in frequency and function, an effect recapitulated by chronic exposure of control HSPCs to low-dose TNFα. These findings implicate CLL B-cell-derived TNFα in impaired BM myelopoiesis.

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CLL patient BM HSPCs exhibit aberrant molecular and functional characteristics

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CLL B-cell-derived TNFα upregulates PU.1 and GATA-2 in BM HSPCs

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The effects of CLL B-cell-derived TNFα are reversible upon TNFα neutralization

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Chronic TNFα exposure in vitro recapitulates ex vivo HSPC functional deficiencies

A study to identify and characterize the stem/progenitor cell in rabbit meniscus

The repair of meniscus in the avascular zone remains a great challenge, largely owing to their limited healing capacity. Stem cells based tissue engineering provides a promising treatment option for damaged meniscus because of their multiple differentiation potential. We hypothesized that meniscus-derived stromal cells (MMSCs) may be present in meniscal tissue, and if their pluripotency and character can be established, they may play a role in meniscal healing. To test our hypothesis, we isolated MMSCs, bone marrow-derived stromal cells (BMSCs) and fibrochondrocytes from rabbits. In order to avoid bone marrow mesenchymal stromal cell contamination, the parameniscal tissues and vascular zone of meniscus were removed. The characters of these three types of cells were identified by evaluating morphology, colony formation, proliferation, immunocytochemistry and multi-differentiation. Moreover, a wound in the center of rabbit meniscus was created and used to analyze the effect of BMSCs and MMSCs on wounded meniscus healing. BMSCs & MMSCs expressed the stem cell markers SSEA-4, Nanog, nucleostemin and STRO-1, while fibrochondrocytes expressed none of these markers. Morphologically, MMSCs displayed smaller cell bodies and larger nuclei than ordinary fibrochondrocytes. Moreover, it was certified that MMSCs and BMSCs were all able to differentiate into adipocytes, osteocytes, and chondrocytes in vitro. However, more cartilage formation was found in wounded meniscus filled with MMSCs than that filled with BMSCs. We showed that rabbit menisci harbor the unique cell population MMSCs that has universal stem cell characteristics and posses a tendency to differentiate into chondrocytes. Future research should investigate the mechanobiology of MMSCs and explore the possibility of using MMSCs to more effectively repair or regenerate injured meniscus.

Mesenchymal stem cells in rabbit meniscus and bone marrow exhibit a similar feature but a heterogeneous multi-differentiation potential: superiority of meniscus as a cell source for meniscus repair

Background

The restoration of damaged meniscus has always been a challenge due to its limited healing capacity. Recently, bone marrow-derived mesenchymal stem cells (BMSCs) provide a promising alternative to repair meniscal defects. However, BMSCs are not ideal chondroprogenitor cells for meniscus repair because they have a high propensity for cartilage hypertrophy and bone formation. Our hypothesis is that mesenchymal stem cells (MSCs) reside in meniscus maintain specific traits distinct from others which may be more conducive to meniscus regeneration.

Methods

MSCs were isolated from bone marrow and menisci of the rabbits. The similarities and differences between BMSCs and MMSCs were investigated in vitro by a cell culture model, ex vivo by a rabbit meniscus defect model and in vivo by a nude rat implantation model using histochemistry, immunocytochemistry, qRT-PCR and western blotting.

Results

Our data showed that two types of MSCs have universal stem cell characteristics including clonogenicity, multi-potency and self-renewal capacity. They both express stem cell markers including SSEA-4, Nanog, nucleostemin, strol-1, CD44 and CD90.

However, MMSCs differed from BMSCs. MMSC colonies were much smaller and grew more slowly than BMSC colonies. Moreover, fewer MMSCs expressed CD34 than BMSCs. Finally, MMSCs always appeared a pronounced tendency to chondrogenic differentiation while BMSCs exhibited significantly greater osteogenic potential, whatever in vitro and in vivo.

Conclusions

This study shows the similarities and differences between MMSCs and BMSCs for the first time. MMSCs are a promising source of mesenchymal stem cells in repairing meniscus defect.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-015-0511-8) contains supplementary material, which is available to authorized users.

Whole genome expression profiling and screening for differentially expressed cytokine genes in human bone marrow endothelial cells treated with humoral inhibitors in liver cirrhosis

Bone marrow endothelial cells (BMECs) are important components of the hematopoietic microenvironment in bone marrow, and they can secrete several types of cytokines to regulate the functions of hematopoietic stem/progenitor cells. To date, it is unknown whether BMECs undergo functional changes and lead to hematopoietic abnormalities in cases of liver cirrhosis (LC). In the present study, whole genome microarray analysis was carried out to detect differentially expressed genes in human BMECs treated for 48 h with medium supplemented with 20% pooled sera from 26 patients with LC or 10 healthy volunteers as the control group. A total of 1,106 upregulated genes and 766 downregulated genes were identified. In Gene Ontology analysis, the most significant categories of genes were revealed. A large number of the upregulated genes were involved in processes, such as cell-cell adhesion, apoptosis and cellular response to stimuli and the downregulated genes were involved in the negative regulation of secretion, angiogenesis, blood vessel development and cell growth. Pathway analysis revealed that the upregulated genes were either cell adhesion molecules or parts of the apoptotic signaling pathway and the downregulated genes were involved in the Wnt signaling pathway and MAPK signaling pathway. These were the pathways with the highest enrichment scores. The results of apoptosis assays revealed that the humoral inhibitors in the sera of patients with LC induced the apoptosis of BMECs, which confirmed the accuracy of bioinformatic analysis. Moreover, we screened and verified 21 differentially expressed cytokine genes [transforming growth factor (TGF)B1, tumor necrosis factor (TNF)B, TNF receptor superfamily, member 11b (TNFRSF11B), TNF (ligand) superfamily, member 13b (TNFSF13B), interleukin (IL)1A, IL6, IL11, IL17C, IL24, family with sequence similarity 3, member B (FAM3B), Fas ligand (FASLG), matrix metallopeptidase (MMP)3, MMP15, vitronectin (VTN), insulin-like growth factor 1 (IGF1), fibroblast growth factor 22 (FGF22), slit homolog 2 (Drosophila) (SLIT2), thrombospondin (THBS)2, THBS3, chemokine (C-C motif) ligand 28 (CCL28) and macrophage stimulating 1 (MST1)] from 97 cytokine genes in BMECs treated with serum from patients with LC. The results from our study demonstrate that the humoral inhibitors in the sera of patients with LC induce the dysfunction and abnormal cytokine secretion by BMECs, which may be a novel mechanism responsible for hematological abnormalities in patients with LC.