Aggregation of human osteoblasts unlocks self-reliant differentiation and constitutes a microenvironment for 3D-co-cultivation with other bone marrow cells

Skeletal bone function relies on both cells and cellular niches, which, when combined, provide guiding cues for the control of differentiation and remodeling processes. Here, we propose an in vitro 3D model based on human fetal osteoblasts, which eases the study of osteocyte commitment in vitro and thus provides a means to examine the influences of biomaterials, substances or cells on the regulation of these processes. Aggregates were formed from human fetal osteoblasts (hFOB1.19) and cultivated under proliferative, adipo- and osteoinductive conditions. When cultivated under osteoinductive conditions, the vitality of the aggregates was compromised, the expression levels of the mineralization-related gene DMP1 and the amount of calcification and matrix deposition were lower, and the growth of the spheroids stalled. However, within spheres under growth conditions without specific supplements, self-organization processes occur, which promote extracellular calcium deposition, and osteocyte-like cells develop. Long-term cultivated hFOB aggregates were free of necrotic areas. Moreover, hFOB aggregates cultivated under standard proliferative conditions supported the co-cultivation of human monocytes, microvascular endothelial cells and stromal cells. Overall, the model presented here comprises a self-organizing and easily accessible 3D osteoblast model for studying bone marrow formation and in vitro remodeling and thus provides a means to test druggable molecular pathways with the potential to promote life-long bone formation and remodeling.

Intrauterine hCG application increases expression of endothelial cell-cell adhesion molecules in human

Endometrial receptivity is a decisive factor in human reproduction. Human chorionic gonadotropin (hCG) is one of the first embryonic signals that precedes the implantation by trophoblast invasion into the endometrium. Meta-analysis of randomized controlled trials reports a moderate-quality evidence for improved live birth rate for an intrauterine hCG dose ≥ 500 IU. Nevertheless, all hCG endometrial effects are not completely understood. We, therefore, utilized endometrial tissue from 12 patients after estradiol and progesterone treatment with or without intrauterine hCG flushing at the window of implantation (WOI) to analyze cellular composition by measuring marker proteins for stromal, endothelial, epithelial and immune cells. Flow cytometry analysis revealed that significantly more cells expressed the endothelial adhesion molecules VE-cadherin (CD144) and S-Endo-1 (CD146) after intrauterine hCG administration. In contrast, the endothelial marker CD31 and markers involved in vessel formation (VEGFR1 and VEGFR2) remained unchanged in their expression. Similarly, stroma markers (CD73, CD90 and CD105), epithelial markers (Desmocollin-2 and E-Cadherin) and immune cell markers (CD11b, CD45, CD79a and HLA-DR) displayed no alterations in their expression. This finding directs the focus on endothelial adhesion molecules as a potential mechanistically explanation of hCG conveyed increase of embryo implantation and pregnancy rates in women undergoing ART.

Treatment of complex recurrent fistula-in-ano by surgery combined to autologous bone marrow-derived mesenchymal stroma cells and platelet-rich plasma injection

PURPOSE

We report a case of successful management of complex recurrent cryptoglandular fistula-in-ano by surgery combined with autologous bone marrow-derived mesenchymal stroma cells (MSCs) and platelet-rich plasma (PRP) injection.

METHODS

Clinical, radiological, and surgical data of the patient were reviewed, as well as the current literature on complex fistula-in-ano.

RESULTS

A 37-year-old man with a recurrent cryptoglandular perianal fistula was addressed to our department. Inflammatory bowel disease was excluded by clinical history, endoscopy, and blood tests. Physical examination and MRI showed an anterior external orifice on the midline, 5 cm from the anal verge, with an internal orifice on the same line. Surgery combined to injection of MSC-PRP solution was successfully performed. MSC-PRP solution was prepared while the patient was under general anesthesia: bone marrow MSCs were obtained by centrifugation of a tibial puncture specimen and PRP from a peripheral whole blood sample of the patient. There were no adverse events post-operatively. Clinical and MRI examination 4 months after treatment confirmed the absence of perianal fistula. More than 2 years after surgery, there has been no recurrence.

CONCLUSIONS

Treatment of complex recurrent cryptoglandular fistula-in-ano by surgery combined to autologous bone marrow-derived MSCs and PRP injection seems safe in selected patients, allowing long-term healing. This procedure seems promising but further evaluation by clinical trials is warranted.

CD14 dictates differential activation of mesenchymal stromal cells through AKT, NF-κB and P38 signals

Mesenchymal stromal cells (MSCs) widely exist in many tissues and have multiple differentiation potential and immunomodulatory capacities. Recently, MSCs have become promising tools for the treatment of various degenerative disorders and autoimmune diseases. The properties of MSCs could be modified in different microenvironments. Thus, it is important to explore the factors controlling MSC function. The presence of Toll-like receptors (TLRs) in MSCs was demonstrated according to previous studies. Consistently, we also illustrated the expression of TLRs in both murine and human MSCs, and displayed that the expression patterns of TLRs in MSCs from different sources. Furthermore, we explored the role of TLR and TLR signaling pathway in MSCs. Interestingly, activation of TLR4-induced expression of cytokines and some specific genes in MSCs. However, MSCs retained much lower mRNA level compared with macrophages. We explored the expression of CD14 in MSCs from different sources, which played a vital role in TLR4 signaling pathway, and found that MSCs are almost negative for CD14. Moreover, only partial activation of TLR4 signaling pathway was observed in MSCs, with no activation of AKT, NF-κB and P38. Here, in the study we defined TLR expression, function and activation in MSCs, which is critical for designing MSC-based therapies.

Role of the microenvironment in myeloid malignancies

The bone marrow microenvironment (BMM) regulates the fate of hematopoietic stem cells (HSCs) in homeostatic and pathologic conditions. In myeloid malignancies, new insights into the role of the BMM and its cellular and molecular actors in the progression of the diseases have started to emerge. In this review, we will focus on describing the major players of the HSC niche and the role of the altered niche function in myeloid malignancies, more specifically focusing on the mesenchymal stroma cell compartment.

[Mesenchymal stromal cells in the treatment of graft-versus-host disease: where do we stand?]

Medicinal products based on mesenchymal stromal cells (MSC) are expected to have a therapeutic benefit in a variety of conditions and, accordingly, are being tested in many clinical studies. The treatment and prevention of graft-versus-host disease (GVHD) is one of the world's most widely studied MSC therapy concepts. So far, one MSC medicinal product has been approved for the treatment of GvHD. This article gives an overview of the particular features related to the production of MSC-based medicinal products, the state of non-clinical research, and the clinical development status of MSCs and the associated challenges, especially in the context of GvHD.

Transcriptome analysis of bone marrow mesenchymal stromal cells from patients with primary myelofibrosis

Primary myelofibrosis (PMF) is a clonal myeloproliferative neoplasm whose severity and treatment complexity are attributed to the presence of bone marrow (BM) fibrosis and alterations of stroma impairing the production of normal blood cells. Despite the recently discovered mutations including the JAK2V617F mutation in about half of patients, the primitive event responsible for the clonal proliferation is still unknown. In the highly inflammatory context of PMF, the presence of fibrosis associated with a neoangiogenesis and an osteosclerosis concomitant to the myeloproliferation and to the increase number of circulating hematopoietic progenitors suggests that the crosstalk between hematopoietic and stromal cells is deregulated in the PMF BM microenvironmental niches. Within these niches, mesenchymal stromal cells (BM-MSC) play a hematopoietic supportive role in the production of growth factors and extracellular matrix which regulate the proliferation, differentiation, adhesion and migration of hematopoietic stem/progenitor cells. A transcriptome analysis of BM-MSC in PMF patients will help to characterize their molecular alterations and to understand their involvement in the hematopoietic stem/progenitor cell deregulation that features PMF.

Mesenchymal stroma cells trigger early attraction of M1 macrophages and endothelial cells into fibrin hydrogels, stimulating long bone healing without long-term engraftment

Implantation of mesenchymal stroma cells (MSCs) is an attractive approach to stimulate closure of large bone defects but an optimal carrier has yet to be defined. MSCs may display trophic and/or immunomodulatory features or stimulate bone healing by their osteogenic activity. The aim of this study was to unravel whether fibrin hydrogel supports early actions of implanted MSCs, such as host cell recruitment, immunomodulation and tissue regeneration, in long bone defects. Female rats received cell-free fibrin or male MSCs embedded in a fibrin carrier into plate-stabilized femoral bone defects. Removed callus was analyzed for host cell invasion (day 6), local cytokine expression (days 3 and 6) and persistence of male MSCs (days 3, 6, 14 and 28). Fibrin-MSC composites triggered fast attraction of host cells into the hydrogel while cell-free fibrin implants were not invaded. A migration front dominated by M1 macrophages and endothelial progenitor cells formed while M2 macrophages remained sparse. Only MSC-seeded fibrin hydrogel stimulated early tissue maturation and primitive vessel formation at day 6 in line with significantly higher VEGF mRNA levels recorded at day 3. Local TNF-α, IL-1β and IL-10 expression indicated a balanced immune cell activity independent of MSC implantation. Implanted MSCs persisted until day 14 but not day 28. Our results demonstrate that fibrin hydrogel is an attractive carrier for MSC implantation into long bone defects, supporting host cell attraction and pro-angiogenic activity. By this angiogenesis, implant integration and tissue maturation was stimulated in long bone healing independent of long-term engraftment of implanted MSCs.

Specific subsets of mesenchymal stroma cells to treat lung disorders--finding the Holy Grail

Accumulating studies, both in animals and human clinical trials with mesenchymal stroma cells (MSC) support the hypothesis of therapeutic effects of these cells in various disorders. However, despite success in immune-mediated disorders such as Crohns' disease, lung disorders such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary disease (IPF) treated with MSC have so far not yielded a revolutionary effect on clinical symptoms. Promising data on immunomodulatory effects in COPD have kept nourishing the research into finding specific traits of MSC beneficial in disease. A heterogeneous population of injected cells might drown a potential therapeutic role of a specific group of MSC. Thus careful analysis of MSC regarding their molecular capabilities such as delivering specific therapeutic vesicles to the environment, or plain cytokine/chemokine fingerprinting might prove useful in augmenting therapies against lung diseases.