Integrated transcriptomic, phenotypic, and functional study reveals tissue-specific immune properties of mesenchymal stromal cells.

Clinical-grade mesenchymal stromal cells (MSCs) can be expanded from bone marrow and adipose tissue to treat inflammatory diseases and degenerative disorders. However, the influence of their tissue of origin on their functional properties, including their immunosuppressive activity, remains unsolved. In this study, we produced paired bone marrow-derived mesenchymal stromal cell (BM-MSC) and adipose-derived stromal cell (ASC) batches from 14 healthy donors. We then compared them using transcriptomic, phenotypic, and functional analyses and validated our results on purified native MSCs to infer which differences were really endowed by tissue of origin. Cultured MSCs segregated together owing to their tissue of origin based on their gene expression profile analyzed using differential expression and weighted gene coexpression network analysis. This translated into distinct immune-related gene signatures, phenotypes, and functional cell interactions. Importantly, sorted native BM-MSCs and ASCs essentially displayed the same distinctive patterns than their in vitro-expanded counterparts. As a whole, ASCs exhibited an immune profile consistent with a stronger inhibition of immune response and a lower immunogenicity, supporting the use of adipose tissue as a valuable source for clinical applications.

CD146 expression on mesenchymal stem cells is associated with their vascular smooth muscle commitment.

Bone marrow mesenchymal stem cells (MSCs) are plastic adherent cells that can differentiate into various tissue lineages, including osteoblasts, adipocytes and chondrocytes. However, this progenitor property is not shared by all cells within the MSC population. In addition, MSCs vary in their proliferation capacity and expression of markers. Because of heterogeneity of CD146 expression in the MSC population, we compared CD146(-/Low) and CD146(High) cells under clonal conditions and after sorting of the non-clonal cell population to determine whether this expression is associated with specific functions. CD146(-/Low) and CD146(High) bone marrow MSCs did not differ in colony-forming unit-fibroblast number, osteogenic, adipogenic and chondrogenic differentiation or in vitro haematopoietic-supportive activity. However, CD146(-/Low) clones proliferated slightly but significantly faster than did CD146(High) clones. In addition, a strong expression of CD146 molecule was associated with a commitment to a vascular smooth muscle cell (VSMC) lineage characterized by a strong up-regulation of calponin-1 and SM22α expression and an ability to contract collagen matrix. Thus, within a bone marrow MSC population, certain subpopulations characterized by high expression of CD146, are committed towards a VSMC lineage.

Phase I trial: the use of autologous cultured adipose-derived stroma/stem cells to treat patients with non-revascularizable critical limb ischemia.

BACKGROUND AIMS: Non-revascularizable critical limb ischemia (CLI) is the most severe stage of peripheral arterial disease, with no therapeutic option. Extensive preclinical studies have demonstrated that adipose-derived stroma cell (ASC) transplantation strongly improves revascularization and tissue perfusion in ischemic limbs. This study, named ACellDREAM, is the first phase I trial to evaluate the feasibility and safety of intramuscular injections of autologous ASC in non-revascularizable CLI patients. METHODS: Seven patients were consecutively enrolled, on the basis of the following criteria: (i) lower-limb rest pain or ulcer; (ii) ankle systolic oxygen pressure <50 or 70 mm Hg for non-diabetic and diabetic patients, respectively, or first-toe systolic oxygen pressure <30 mm Hg or 50 mm Hg for non-diabetic and diabetic patients, respectively; (iii) not suitable for revascularization. ASCs from abdominal fat were grown for 2 weeks and were then characterized. RESULTS: More than 200 million cells were obtained, with almost total homogeneity and no karyotype abnormality. The expressions of stemness markers Oct4 and Nanog were very low, whereas expression of telomerase was undetectable in human ASCs compared with human embryonic stem cells. ASCs (10(8)) were then intramuscularly injected into the ischemic leg of patients, with no complication, as judged by an independent committee. Trans-cutaneous oxygen pressure tended to increase in most patients. Ulcer evolution and wound healing showed improvement. CONCLUSIONS: These data demonstrate the feasibility and safety of autologous ASC transplantation in patients with objectively proven CLI not suitable for revascularization. The improved wound healing also supports a putative functional efficiency.

Adipose-derived mesenchymal stem cells exert antiinflammatory effects on chondrocytes and synoviocytes from osteoarthritis patients through prostaglandin E2.

OBJECTIVE: To examine the effect of different sources of good manufacturing practice clinical grade adipose-derived mesenchymal stem cells (AD-MSCs) on inflammatory factors in osteoarthritic (OA) chondrocytes and synoviocytes. METHODS: AD-MSCs from infrapatellar Hoffa fat, subcutaneous (SC) hip fat, and SC abdominal fat were cocultured in Transwells with chondrocytes or synoviocytes. Inflammatory factors (interleukin-1ß [IL-1ß], tumor necrosis factor α, IL-6, CXCL1/growth-related oncogene α, CXCL8/IL-8, CCL2/monocyte chemotactic protein 1, CCL3/macrophage inflammatory protein 1α, and CCL5/RANTES) were evaluated by quantitative reverse transcription-polymerase chain reaction or multiplex bead-based immunoassay. The role of different immunomodulators was analyzed. RESULTS: All the inflammatory factors analyzed were down-modulated at the messenger RNA or protein level independently by all 3 AD-MSC sources or by allogeneic AD-MSCs used in coculture with chondrocytes or synoviocytes. Inflammatory factor down-modulation was observed only when AD-MSCs were cocultured with chondrocytes or synoviocytes that produced high levels of inflammatory factors, but no effect was observed in cells that produced low levels of those factors, thus highlighting a dependence of the AD-MSC effect on existing inflammation. The immunomodulators IL-10, IL-1 receptor antagonist, fibroblast growth factor 2, indoleamine 2,3-dioxygenase 1, and galectin 1 were not involved in AD-MSC effects, whereas the cyclooxygenase 2 (COX-2)/prostaglandin E2 (PGE2 ) pathway exerted a role in the mechanism of antiinflammatory AD-MSC action. CONCLUSION: The antiinflammatory effects of AD-MSCs are probably not dependent on AD-MSC adipose tissue sources and donors but rather on the inflammatory status of OA chondrocytes and synoviocytes. AD-MSCs seem to be able to sense and respond to the local environment. Even though a combination of different molecules may be involved in AD-MSC effects, the COX-2/PGE2 pathway may play a role, suggesting that AD-MSCs may be useful for therapies in osteoarticular diseases.

Long-term detection of human adipose-derived mesenchymal stem cells after intraarticular injection in SCID mice.

OBJECTIVE: Mesenchymal stem cells (MSCs) represent a promising tool for cell therapy for several disorders, among them the osteoarticular diseases. For such clinical applications, intraarticular (IA) injection of MSCs may be favored for higher levels of safety and targeting of specific joints. Although the safety of intravenous (IV) administration of MSCs has been reported in a number of clinical trials, the safety and biodistribution of MSCs after IA injection have not been tested. Our objective was to assess the toxicity of clinical-grade human adipose-derived MSCs (AD-MSCs), as well as their biodistribution, after IA injection into SCID mice. METHODS: SCID mice received IA or IV administration of 10(6) human AD-MSCs. Several tissues were recovered at different time points and processed for histologic assessment or real-time polymerase chain reaction (PCR) analysis. A highly sensitive assay was used to monitor the distribution of AD-MSCs, based on amplification of human-specific Alu sequences. RESULTS: Absence of toxicity was observed after AD-MSC infusion. Alu PCR assay revealed a high sensitivity (1 human AD-MSC/10(5) murine cells), with a large linear range (1-5 × 10(4) /10(5) murine cells). Importantly, 15% of the IA-injected AD-MSCs were detectable in the joint for the first month and 1.5% of the AD-MSCs engrafted over the long term, at least 6 months. AD-MSCs were observed in the injected joints and in areas of tissue referred to as stem cell niches, such as the bone marrow, adipose tissue, and muscle. CONCLUSION: These data support the feasibility and safety of using IA delivery of human AD-MSCs in the treatment of rheumatic diseases that affect the joints.

Stromal cells from the adipose tissue-derived stromal vascular fraction and culture expanded adipose tissue-derived stromal/stem cells: a joint statement of the International Federation for Adipose Therapeutics and Science (IFATS) and the International Society for Cellular Therapy (ISCT).

BACKGROUND AIMS: Adipose tissue is a rich and very convenient source of cells for regenerative medicine therapeutic approaches. However, a characterization of the population of adipose-derived stromal and stem cells (ASCs) with the greatest therapeutic potential remains unclear. Under the authority of International Federation of Adipose Therapeutics and International Society for Cellular Therapy, this paper sets out to establish minimal definitions of stromal cells both as uncultured stromal vascular fraction (SVF) and as an adherent stromal/stem cells population. METHODS: Phenotypic and functional criteria for the identification of adipose-derived cells were drawn from the literature. RESULTS: In the SVF, cells are identified phenotypically by the following markers: CD45-CD235a-CD31-CD34+. Added value may be provided by both a viability marker and the following surface antigens: CD13, CD73, CD90 and CD105. The fibroblastoid colony-forming unit assay permits the evaluation of progenitor frequency in the SVF population. In culture, ASCs retain markers in common with other mesenchymal stromal/stem cells (MSCs), including CD90, CD73, CD105, and CD44 and remain negative for CD45 and CD31. They can be distinguished from bone-marrow-derived MSCs by their positivity for CD36 and negativity for CD106. The CFU-F assay is recommended to calculate population doublings capacity of ASCs. The adipocytic, chondroblastic and osteoblastic differentiation assays serve to complete the cell identification and potency assessment in conjunction with a quantitative evaluation of the differentiation either biochemically or by reverse transcription polymerase chain reaction. CONCLUSIONS: The goal of this paper is to provide initial guidance for the scientific community working with adipose-derived cells and to facilitate development of international standards based on reproducible parameters.

Impact of rituximab on stem cell mobilization following ACVBP regimen in poor-risk patients with diffuse large B-cell lymphoma: results from a large cohort of patients.

BACKGROUND: The ACVBP regimen is an efficient induction regimen for poor-risk patients with diffuse large B-cell lymphoma (DLBCL) before consolidative autologous stem cell transplantation. Adjunction of the monoclonal anti-CD20 antibody rituximab (R-ACVBP) was recently found to be superior to ACVBP alone. This study assessed the impact of rituximab on stem cell mobilization in two similar consecutive groups of patients treated with ACVBP in two prospective, controlled trials. STUDY DESIGN AND METHODS: The first trial (LNH-98B-3) involved 137 patients treated with ACVBP alone. In the second trial (LNH-03-3B), 91 patients received an R-ACVBP regimen. Stem cell mobilization was performed after a course of (R)-ACVBP. RESULTS: The median peak numbers of blood CD34+ cell counts recorded before the first apheresis procedure in the ACVBP and R-ACVBP groups were 69×10(6) and 63×10(6) /L, respectively (p=0.55). The median numbers of CD34+ cells collected were 7.1×10(6) and 6.0×10(6) CD34+ cells/kg for the ACVBP and R-ACVBP groups, respectively (p=0.13). The median number of apheresis procedures required for gathering the minimum amount of CD34+ cells (2×10(6) /kg) was the same in the two groups. CONCLUSION: When compared with ACVBP alone, adjunction of rituximab does not impair stem cell mobilization.

Platelet lysate from whole blood-derived pooled platelet concentrates and apheresis-derived platelet concentrates for the isolation and expansion of human bone marrow mesenchymal stromal cells: production process, content and identification of active components.

BACKGROUND AIMS: The clinical use of human mesenchymal stromal cells (MSC) requires ex vivo expansion in media containing supplements such as fetal bovine serum or, alternatively, human platelet lysate (PL). METHODS: Platelet concentrates were frozen, quarantine stored, thawed and sterile filtered to obtain PL. PL content and its effect on fibroblast-colony-forming unit (CFU-F) formation, MSC proliferation and large-scale expansion were studied. RESULTS: PL contained high levels of basic fibroblast growth factor (bFGF), soluble CD40L (sCD40L), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), platelet-derived growth factor AA (PDGF-AA), platelet-derived growth factor AB/BB (PDGF-AB/BB), chemokine (C-C) ligand 5 (CCL5; RANTES) transforming growth factor-ß1 (TGF-ß1) and chemokine (C-X-C) ligand 1/2/3 (GRO), with low batch-to-batch variability, and most were stable for up to 14 days. Inhibition of PDGF-BB and bFGF decreased MSC proliferation by about 20% and 50%, respectively. The strongest inhibition (about 75%) was observed with a combination of anti-bFGF + anti-PDGF-BB and anti-bFGF + anti-TGF-ß1 + anti-PDGF-BB. Interestingly, various combinations of recombinant PDGF-BB, bFGF and TGF-ß1 were not sufficient to promote cell proliferation. PL from whole blood-derived pooled platelet concentrates and apheresis platelet concentrates did not differ significantly in their growth-promoting activity on MSC. CONCLUSIONS: PL enhances MSC proliferation and can be regarded as a safe tool for MSC expansion for clinical purposes. \in particular, PDGF-BB and bFGF are essential components for the growth-promoting effect of PL, but are not sufficient for MSC proliferation.

Dual-energy X-ray absorptiometry and biochemical markers of bone turnover after autologous stem cell transplantation in myeloma.

OBJECTIVES: To evaluate the effect of high-dose chemotherapy (HDT) followed by autologous stem cell transplantation (ASCT) on bone turnover and bone mineral density in a cohort of 39 consecutive patients with multiple myeloma (MM). METHODS: Phosphorus and calcium parameters, bone turnover markers, and bone mineral density were studied. Timepoints were diagnosis (T1), just before ASCT (T2), 6 months (T3) after ASCT, and 1 yr (T4) after ASCT. RESULTS: No bone mineral loss was shown on dual-energy X-ray absorptiometry (DXA) at T1 (lumbar Z-score -0.02, femoral neck Z-score 0.77) or during follow-up. Chronic vitamin D deficiency (25OHD3 11.7 ± 7.7 ng/mL at T1) and relative hyperparathyroidism from T2 to T4 were observed. In spite of this moderate hyperparathyroidism, serum C-telopeptide of type I collagen (CTX) decreased significantly between T1 and T4. Bone alkaline phosphatase levels were low at diagnosis and showed no significant change after ASCT, unlike DKK1 levels that were high at diagnosis and decreased 6 months after ASCT in patients not previously treated with bisphosphonates. CONCLUSION: Bone demineralization is moderate in multiple myeloma. ASCT induces a decrease in bone resorption but no changes in bone formation, remaining low despite the decrease in DKK1. Bone mineral loss, evaluated by DXA, is moderate in multiple myeloma. High-dose chemotherapy followed by ASCT leads to decreased bone resorption but osteoblastic bone formation remains low, in spite of reduced circulating DKK1.

Intracoronary autologous mononucleated bone marrow cell infusion for acute myocardial infarction: results of the randomized multicenter BONAMI trial.

AIMS: Intracoronary administration of autologous bone marrow cells (BMCs) leads to a modest improvement in cardiac function, but the effect on myocardial viability is unknown. The aim of this randomized multicentre study was to evaluate the effect of BMC therapy on myocardial viability in patients with decreased left ventricular ejection fraction (LVEF) after acute myocardial infarction (AMI) and to identify predictive factors for improvement of myocardial viability. METHODS AND RESULTS: One hundred and one patients with AMI and successful reperfusion, LVEF ≤45%, and decreased myocardial viability (resting Tl201-SPECT) were randomized to either a control group (n = 49) or a BMC group (n = 52). Primary endpoint was improvement of myocardial viability 3 months after AMI. Baseline mean LVEF measured by radionuclide angiography was 36.3 ± 6.9%. Bone marrow cell infusion was performed 9.3 ± 1.7 days after AMI. Myocardial viability improved in 16/47 (34%) patients in the BMC group compared with 7/43 (16%) in the control group (P = 0.06). The number of non-viable segments becoming viable was 0.8 ± 1.1 in the control group and 1.2 ± 1.5 in the BMC group (P = 0.13). Multivariate analysis including major post-AMI prognostic factors showed a significant improvement of myocardial viability in BMC vs. control group (P = 0.03). Moreover, a significant adverse role for active smoking (P = 0.04) and a positive trend for microvascular obstruction (P = 0.07) were observed. CONCLUSION: Intracoronary autologous BMC administration to patients with decreased LVEF after AMI was associated with improvement of myocardial viability in multivariate-but not in univariate-analysis. A large multicentre international trial is warranted to further document the efficacy of cardiac cell therapy and better define a group of patients that will benefit from this therapy. CLINICAL TRIAL REGISTRATION INFORMATION: URL: http://www.clinicaltrials.gov. Unique identifier NCT00200707.

Toll-like receptor 4 selective inhibition in medullar microenvironment alters multiple myeloma cell growth.

Bone marrow (BM) mesenchymal stromal cells (MSCs) are abnormal in multiple myeloma (MM) and play a critical role by promoting growth, survival, and drug resistance of MM cells. We observed higher Toll-like receptor 4 (TLR4) gene expression in MM MSCs than in MSCs from healthy donors. At the clinical level, we highlighted that TLR4 expression in MM MSCs evolves in parallel with the disease stage. Thus, we reasoned that the TLR4 axis is pivotal in MM by increasing the protumor activity of MSCs. Challenging primary MSCs with TLR4 agonists increased the expression of CD54 and interleukin-6 (IL-6), 2 factors directly implicated in MM MSC-MM cell crosstalk. Then, we evaluated the therapeutic efficacy of a TLR4 antagonist combined or not with conventional treatment in vitro with MSC-MM cell coculture and in vivo with the Vk*MYC mouse model. Selective inhibition of TLR4 specifically reduced the MM MSC ability to support the growth of MM cells in an IL-6-dependent manner and delayed the development of MM in the Vk*MYC mouse model by altering the early disease phase in vivo. For the first time, we demonstrate that specific targeting of the pathological BM microenvironment via TLR4 signaling could be an innovative approach to alter MM pathology development.

[Mesenchymal stem cells - The challenge of a good therapeutic product]. / Cellules souches mésenchymateuses - Production à usage clinique et contraintes sécuritaires.

Mesenchymal stem cells (or stromal cells) have been initially characterized in bone marrow, but since, they have been identified in almost every tissue. Their multiple properties, namely differentiative capacity, production of cytokines and trophic molecules, and their immunosuppressive potential undoubtedly offer many therapeutic advantages, both for regenerative medecine or to relieve immune or inflammatory diseases. This is illustrated by the high number (> 100) of ongoing clinical trials with these cells. However, a prerequsite for their safe use in clinics is to guarantee that their production meet the good manufacturing practices, and that the final product is validated by adequate controls. It is thus quite a challenge to move from procedures defined for a research use to large scale production that fits with the national and international rules in terms of standardisation and controls. This underlines the importance of developping interacting networks between research teams, physicians and the industrial R&D departments. This fruitful collaboration will ensure the definition of appropriate and safe procedures for a successful therapeutic application.

Hospicells (ascites-derived stromal cells) promote tumorigenicity and angiogenesis.

The microenvironment is known to play a dominant role in cancer progression. Cells closely associated with tumoral cells, named hospicells, have been recently isolated from the ascites of ovarian cancer patients. Whilst these cells present no specific markers from known cell lineages, they do share some homology with bone marrow-derived or adipose tissue-derived human mesenchymal stem cells (CD9, CD10, CD29, CD146, CD166, HLA-1). We studied the role of hospicells in ovarian carcinoma progression. In vitro, these cells had no effect on the growth of human ovarian carcinoma cell lines OVCAR-3, SKOV-1 and IGROV-1. In vivo, their co-injection with adenocarcinoma cells enhanced tumor growth whatever the tumor model used (subcutaneous and intraperitoneally established xenografts in athymic mice). In addition, their injection increased the development of ascites in tumor-bearing mice. Fluorescent macroscopy revealed an association between hospicells and ovarian adenocarcinoma cells within the tumor mass. Tumors obtained by coinjection of hospicells and human ovarian adenocarcinoma cells presented an increased microvascularization indicating that the hospicells could promote tumorigenicity of ovarian tumor cells in vivovia their action on angiogenesis. This effect on angiogenesis could be attributed to the increased HIF1alpha and VEGF expression associated with the presence of the hospicells. Collectively, these data indicate a role for these ascite-derived stromal cells in promoting tumor growth by increasing angiogenesis.

Human fibroblasts share immunosuppressive properties with bone marrow mesenchymal stem cells.

INTRODUCTION: Bone marrow mesenchymal stem cells (BM-MSCs) and adipose tissue-derived stem cells share immunosuppressive capacities, suggesting that the latter could be a general property of stromal cells. METHODS: To check this hypothesis, we compared human BM-MSC and fibroblasts for their in vitro multi-potentiality, expandability and their immunomodulatory properties under normalized optimized culture conditions. RESULTS: We report that, unlike BM-MSCs, fibroblasts cannot differentiate in vitro into adipocytes and osteoblasts and differ from BM-MSCs by the expression of membrane CD106, CD10 and CD26 and by the expression of collagen VII mRNA. Like BM-MSCs, fibroblasts are unable to provoke in vitro allogeneic reactions, but strongly suppress lymphocyte proliferation induced by allogeneic mixed lymphocyte culture (MLC) or mitogens. We show that fibroblasts' immunosuppressive capacity is independent from prostaglandin E2, IL-10 and the tryptophan catabolising enzyme indoleamine 2,3-dioxygenase and is not abrogated after the depletion of CD8+ T lymphocytes, NK cells and monocytes. CONCLUSION: Finally, fibroblasts and BM-MSCs act at an early stage through blockage of lymphocyte activation, as demonstrated by down-regulation of GZMB (granzyme B) and IL2RA (CD25) expression.

A regulatory cross-talk between Vgamma9Vdelta2 T lymphocytes and mesenchymal stem cells.

The physiological functions of human TCRVgamma9Vdelta2(+) gammadelta lymphocytes reactive to non-peptide phosphoantigens contribute to cancer immunosurveillance and immunotherapy. However, their regulation by mesenchymal stem cells (MSC), multipotent and immunomodulatory progenitor cells able to infiltrate tumors, has not been investigated so far. By analyzing freshly isolated TCRVgamma9Vdelta2(+) lymphocytes and primary cell lines stimulated with synthetic phosphoantigen or B-cell lymphoma cell lines in the presence of MSC, we demonstrated that MSC were potent suppressors of gammadelta-cell proliferation, cytokine production and cytolytic responses in vitro. This inhibition was mediated by the COX-2-dependent production of prostaglandin E2 (PGE(2)) and by MSC through EP2 and EP4 inhibitory receptors expressed by Vgamma9Vdelta2 T lymphocytes. COX-2 expression and PGE(2) production by MSC were not constitutive, but were induced by IFN-gamma and TNF-alpha secreted by activated Vgamma9Vdelta2 T cells. This regulatory cross-talk between MSC and Vgamma9Vdelta2 T lymphocytes involving PGE(2) could be of importance for the antitumor and antimicrobial activities of gammadelta T cells.

Mesenchymal stem cells promote matrix metalloproteinase secretion by cardiac fibroblasts and reduce cardiac ventricular fibrosis after myocardial infarction.

Recent studies showed that mesenchymal stem cells (MSCs) transplantation significantly decreased cardiac fibrosis; however, the mechanisms involved in these effects are still poorly understood. In this work, we investigated whether the antifibrotic properties of MSCs involve the regulation of matrix metalloproteinases (MMPs) and matrix metalloproteinase endogenous inhibitor (TIMP) production by cardiac fibroblasts. In vitro experiments showed that conditioned medium from MSCs decreased viability, alpha-smooth muscle actin expression, and collagen secretion of cardiac fibroblasts. These effects were concomitant with the stimulation of MMP-2/MMP-9 activities and membrane type 1 MMP expression. Experiments performed with fibroblasts from MMP2-knockout mice demonstrated that MMP-2 plays a preponderant role in preventing collagen accumulation upon incubation with conditioned medium from MSCs. We found that MSC-conditioned medium also decreased the expression of TIMP2 in cardiac fibroblasts. In vivo studies showed that intracardiac injection of MSCs in a rat model of postischemic heart failure induced a significant decrease in ventricular fibrosis. This effect was associated with the improvement of morphological and functional cardiac parameters. In conclusion, we showed that MSCs modulate the phenotype of cardiac fibroblasts and their ability to degrade extracellular matrix. These properties of MSCs open new perspectives for understanding the mechanisms of action of MSCs and anticipate their potential therapeutic or side effects.

Functional Comparison between Healthy and Multiple Myeloma Adipose Stromal Cells.

Multiple myeloma (MM) is an incurable B cell neoplasia characterized by the accumulation of tumor plasma cells within the bone marrow (BM). As a consequence, bone osteolytic lesions develop in 80% of patients and remain even after complete disease remission. We and others had demonstrated that BM-derived mesenchymal stromal cells (MSCs) are abnormal in MM and thus cannot be used for autologous treatment to repair bone damage. Adipose stromal cells (ASCs) represent an interesting alternative to MSCs for cellular therapy. Thus, in this study, we wondered whether they could be a good candidate in repairing MM bone lesions. For the first time, we present a transcriptomic, phenotypic, and functional comparison of ASCs from MM patients and healthy donors (HDs) relying on their autologous MSC counterparts. In contrast to MM MSCs, MM ASCs did not exhibit major abnormalities. However, the changes observed in MM ASCs and the supportive property of ASCs on MM cells question their putative and safety uses at an autologous or allogenic level.

Ex vivo pretreatment with melatonin improves survival, proangiogenic/mitogenic activity, and efficiency of mesenchymal stem cells injected into ischemic kidney.

Bone marrow mesenchymal stem cells (MSCs) have shown great potential in cell therapy of solid organs. Approaches to improving the ability of grafted MSCs to survive and secrete paracrine factors represent one of the challenges for the further development of this novel therapy. In the present study, we designed a strategy of ex vivo pretreatment with the pineal hormone melatonin to improve survival, paracrine activity, and efficiency of MSCs. Using a rat model of acute renal failure, we showed that melatonin pretreatment strongly increased survival of MSCs after intraparenchymal injection. This effect was concomitant with overstimulation of angiogenesis, proliferation of renal cells, and accelerated recovery of renal function. To gain insight into the mechanisms involved in the effects observed in vivo, melatonin was tested in vitro on cultured MSCs. Our results show that through stimulation of specific melatonin receptors, melatonin induced an overexpression of the antioxidant enzyme catalase and superoxide dismutase-1 and increased the resistance of MSCs to hydrogen peroxide-dependent apoptosis. Compared with untreated cells, MSCs incubated with melatonin displayed a higher expression of basic fibroblast growth factor and hepatocyte growth factor. In addition, conditioned culture media from melatonin-treated MSCs stimulated tube formation by endothelial progenitor cells and proliferation of proximal tubule cells in culture. In conclusion, our results show that melatonin behaves as a preconditioning agent increasing survival, paracrine activity, and efficiency of MSCs. The use of this molecule for pretreatment of stem cells may represent a novel and safe approach to improving the beneficial effects of cell therapy of solid organs.

Mesenchymal Progenitor Cells: Tissue Origin, Isolation and Culture.

SUMMARY: Since the pioneering work of Alexander Friedenstein on multipotent mesenchymal stromal cells (MSCs), a tremendous amount of work has been done to isolate, characterize and culture such cells. Assay of colony forming unit-fibroblasts (CFU-Fs), the hallmark of MSCs, is used to estimate their frequency in tissue. MSCs are adherent cells, so they are easy to isolate, and they show contact inhibition. Thus, several parameters must be taken into account for culture: cell density, number of passages, culture medium, and growth factors used. The purity of the initial material is not a limiting parameter. Similar but not identical cell populations are found in almost all mammal or human tissues. MSCs seem to be very abundant in adipose tissue but at low frequency in blood from umbilical cord or in adult tissue. The culture conditions are very similar, whatever the source of cells. Because of their favorable properties, MSCs are very promising tools for regenerative medicine.