Multi-laboratory assay for harmonization of enumeration of viable CD34+ and CD45+ cells in frozen cord blood units.

BACKGROUND AIMS: In 2016, specifications for both pre-cryopreserved and post-thawed cord blood were defined in the sixth edition of NetCord Foundation for the Accreditation of Cellular Therapy (FACT) Standards for Cord Blood Banks. However, for several experts, harmonization regarding flow cytometry analysis performed on post-thawed samples is still a concern. A multicenter study led by Héma-Québec aimed to provide scientific data to support the cord blood accreditation bodies such as NetCord FACT in the revision of standards. METHODS: Twelve cord blood units were processed for plasma and red cell reduction following standard operating procedures. Cord blood unit aliquots were shipped to eight participating centers under cryogenic conditions for analysis before and after standardization of protocol. Repeatability of stem cell count, measured pre- and post-intervention with the centers, was estimated using multilevel linear regression models with a heterogeneous compound symmetry correlation structure among repeated measures. RESULTS: Excellent inter-center repeatability was reported by each participant regarding the viable CD34+ cells concentration, and a successful improvement effect of protocol standardization was also observed. However, we observed that better control over the critical parameters of the protocol did not have a significant effect on improving homogeneity in the enumeration of CD45+ cells. CONCLUSIONS: The current practice in cord blood selection should now also consider relying on post-thaw CD34+ concentration, providing that all cord blood banks or outsourcing laboratories in charge of the analysis of post-thaw CB samples take into account the consensual recommendations provided in this work and adhere to a good-quality management system.

Fully automated, clinical-grade bone marrow processing: a single-centre experience.

BACKGROUND: Clinical grade processing of harvested bone marrow is required in various clinical situations, particularly in the management of ABO mismatching in allogeneic haematopoietic stem cell transplantation (HSCT) and in regenerative medicine. MATERIAL AND METHODS: We report a single-centre experience using a fully automated, clinical grade, closed system (Sepax, Biosafe, Switzerland). From 2003 to 2015, 125 procedures were performed in our laboratory, including buffy-coat production for HSCT (n=58), regenerative medicine in an orthopaedic setting (n=54) and density-gradient separation in a trial for treatment of critical limb ischaemia (n=13). RESULTS: Buffy coat separation resulted in a median volume reduction of 85% (range, 75-87%), providing satisfactory red blood cell depletion (69%, range 30-88%) and a median recovery of CD34 cells of 96% (range, 81-134%) in the setting of allogeneic HSCT. Significantly greater volume reduction (90%; range, 90-92%) and red blood cell depletion (88%; range, 80-93%) were achieved by the new SmartRedux software released for Sepax2, validated in the last eight allogeneic HSCT. The density gradient separation programme resulted in complete red blood cell depletion associated with high CD34 recovery (69%; range, 36-124%). No reactions related to the quality of the product were reported. Time to engraftment following allogeneic HSCT was in the normal range. No cases of microbiological contamination related to the manipulation were reported. DISCUSSION: Clinical grade, automated bone marrow manipulation with Sepax was shown to be effective, giving operator-independent results and could be used for a broad range of clinical applications.

Dendritic cells with lymphocyte-stimulating activity differentiate from human CD133 positive precursors.

CD133 is a hallmark of primitive myeloid progenitors. We have addressed whether human cord blood cells selected for CD133 can generate dendritic cells, and Langerhans cells in particular, in conditions that promote that generation from CD34(+) progenitors. Transforming growth factor-ß1 (TGF-ß1) and anti-TGF-ß1 antibody, respectively, were added in some experiments. With TGF-ß, monocytoid cells were recognized after 7 days. Immunophenotypically immature dendritic cells were present at day 14. After 4 more days, the cells expressed CD54, CD80, CD83, and CD86 and were potent stimulators in mixed lymphocyte reaction; part of the cells expressed CD1a and langerin, but not Birbeck granules. Without TGF-ß, only a small fraction of cells acquired a dendritic shape and expressed the maturation-related antigens, and lymphocytes were poorly stimulated. With anti-TGF-ß, the cell growth was greatly hampered, CD54 and langerin were never expressed, and lymphocytes were stimulated weakly. In conclusion, CD133(+) progenitors can give rise in vitro, through definite steps, to mature, immunostimulatory dendritic cells with molecular features of Langerhans cells, although without Birbeck granules. Addition of TGF-ß1 helps to stimulate cell growth and promotes the acquisition of mature immunophenotypical and functional features. Neither langerin nor Birbeck granules proved indispensable for lymphocyte stimulation.

Human mesenchymal stromal cells preserve their stem features better when cultured in the Dulbecco's modified Eagle medium.

BACKGROUND AIMS: The human mesenchymal stromal cell (hMSC), a type of adult stem cell with a fibroblast-like appearance, has the potential to differentiate along the mesenchymal lineage and also along other cell lineages. These abilities make hMSC a promising candidate for use in regenerative medicine. As the hMSC represents a very rare population in vivo, in vitro expansion is necessary for any clinical use. hMSC characterization is commonly carried out through the expression of specific markers and by the capability of differentiating toward at least adipo-, osteo- and chondrocytic lineages. Commitment processes also result in significant changes in the ultrastructure in order to acquire new functional abilities; however, few studies have dealt with the ultrastructural characteristics of hMSC according to the time of incubation and type of media. METHODS: The immunophenotype, functional characteristics and ultrastructural features of bone marrow (BM) hMSC cultured in two different media were investigated. The media chosen were Iscove's modified Dulbecco's medium (IMDM) and the Dulbecco's modified Eagle medium (DMEM). The latter has been recommended recently by two international transplantation and cytotherapy societies, the International Society of Cellular Therapy (ISCT) and European Group for Blood and Bone Marrow Transplantation (EBMT), for hMSC expansion for clinical applications. RESULTS AND CONCLUSIONS: The present results indicate that culture conditions greatly influence hMSC ultrastructural features, proliferation, growth and differentiation. In particular, our findings demonstrate that DMEM preserves the hMSC stem features better. Furthermore, the results obtained in IMDM suggest that a small size does not always correlate with conditions of cell immaturity and a greater proliferative potential.

Mesenchymal stem cells prevent acute rejection and prolong graft function in pancreatic islet transplantation.

BACKGROUND: Pancreatic islet transplantation is a promising cell-based therapy for type 1 diabetes (insulin-dependent diabetes mellitus), a disease triggered by the immune response against autoantigens of beta-cells. However, the recurrence of immune response after transplantation and the diabetogenic and growth-stunting side effects of immunosuppressants are major challenges to the application of islet transplantation. Mesenchymal stem cells (MSCs) have recently been reported to modulate the immune response in allogeneic transplantation. METHODS: The ability of MSCs, either syngeneic or allogeneic to recipients, to prevent acute rejection and improve glycemic control was investigated in rats with diabetes given a marginal mass of pancreatic islets through the portal vein. RESULTS: Reduced glucose levels and low-grade rejections were observed up to 15 days after transplantation upon triple-dose administration of MSCs, indicating that MSCs prolong graft function by preventing acute rejection. The efficacy of MSCs was associated with a reduction of pro-inflammatory cytokines and was independent of the administration route. Efficacy was similar for MSCs whether syngeneic or allogeneic to recipients and comparable to that of immunosuppressive therapy. CONCLUSIONS: The results show that MSCs modulate the immune response through a down-regulation of pro-inflammatory cytokines, suggesting that MSCs may prevent acute rejection and improve graft function in portal vein pancreatic islet transplantation.

High recovery of mesenchymal progenitor cells with non-density gradient separation of human bone marrow.

BACKGROUND AIMS: Bone marrow (BM) is the most used source of hemopoietic stem cells (HSC) and mesenchymal stromal cells (MSC) in both hematologic settings and regenerative medicine. We compared the feasibility and reproducibility of two gravity separation techniques, with or without the use of a density gradient, in terms of both hematopoietic and mesenchymal human BM progenitors. METHODS: A total of 16 BM samples was processed to obtain mononuclear cells (MNC) and buffy coats (BC). The efficiency of the two procedures was evaluated by recovery of white blood cells (WBC), MNC and CD34(+) cells, clonogenic assays, red blood cell (RBC) depletion, cell viability, expression of embryonic transcriptional regulators and MSC assessment. RESULTS: The two procedures yielded a comparable recovery of HSC. Non-density gradient separation (NDGS) of BM resulted in four times higher MSC recovery and higher expression of embryonic stem cell markers (Nanog and Sox2) compared with density-gradient separation (DGS). MSC derived from both procedures was comparable in terms of phenotype, differentiation and proliferation potential. CONCLUSIONS: NDGS is less time consuming, provides a better MSC enrichment and appears to be a suitable cell preparation method for clinical applications.

Human striatal neuroblasts develop and build a striatal-like structure into the brain of Huntington's disease patients after transplantation.

Rebuilding brain structure and neural circuitries by transplantation of fetal tissue is a strategy to repair the damaged nervous system and is currently being investigated using striatal primordium in Huntington's disease (HD) patients. Four HD patients underwent bilateral transplantation with human fetal striatal tissues (9-12 week gestation). Small blocks of whole ganglionic eminencies were processed to obtain cell suspension and then stereotactically grafted in the caudate head and in the putamen. Follow-up period ranged between 18 and 34 months (mean, 24.7 months). Surgery was uneventful. Starting from the fourth month after grafting, neo-generation of metabolically active tissue with striatal-like MRI features was observed in 6 out of 8 grafts. The increase in D2 receptor binding suggested striatal differentiation of the neo-generated tissue in 3 patients. New tissue, connecting the developing grafts with the frontal cortex and, in one case, with the ventral striatum, was also observed. The new tissue growth halted after the ninth month post transplantation. All patients showed stabilization or improvement in some neurological indices. No clinical and imaging signs, suggestive of graft uncontrolled growth, were seen. This study provides the first evidence in humans that neuroblasts of a striatal primordium can develop and move into the brain after neurotransplantation. Primordium development resulted in the building of a new structure with the same imaging features as the corresponding mature structure, combined with short- and long-distance targeted migration of neuroblasts. The results of this study support both the reconstructive potential of fetal tissue and the remarkably retained plasticity of adult brain. Further studies are necessary to assess the clinical efficacy of the human fetal striatal transplantation.

Cochlear repair by transplantation of human cord blood CD133+ cells to nod-scid mice made deaf with kanamycin and noise.

We investigated the fate of human cord blood CD133+ hematopoietic stem cells (HSC) transplanted intravenously (IV) into irradiated nod-scid mice previously made deaf by ototoxic treatment with kanamycin and/ or intense noise, to verify whether HSC engraft the cochlea and contribute to inner ear restoration, in vivo. We tested the presence of HLA.DQalpha1 by PCR, used for traceability of engrafted cells, finding evidence that HSC migrated to various host tissues, including the organ of Corti (OC). By histology, antibody and lectin-staining analysis, we confirmed that HSC IV transplantation in mice previously damaged by ototoxic agents correlated with the repair process and stimulation ex novo of morphological recovery in the inner ear, while the cochlea of control oto-injured, nontransplanted mice remained seriously damaged. Dual color FISH analysis also provided evidence of positive engraftment in the inner ear and in various mouse tissues, also revealing small numbers of heterokaryons, probably derived from fusion of donor with endogenous cells, for up to 2 months following transplantation. These observations offer the first evidence that transplanted human HSC migrating to the inner ear of oto-injured mice may provide conditions for the resumption of deafened cochlea, emerging as a potential strategy for inner ear rehabilitation.

Differences in mesenchymal stem cell cytokine profiles between MS patients and healthy donors: implication for assessment of disease activity and treatment.

MSCs have been proposed as possible treatment in MS: In this study MSCs obtained from 10 MS patients and 6 healthy donors (HD) were compared in terms of phenotypical and functional characteristics. We show that MSCs isolated from MS and HD differ significantly for IP10 production. Therefore, although MSCs isolated from MS patients exhibit the same properties of HD MSCs in terms of proliferation, phenotype, in vitro differentiation, TLR expression, immunosuppressive ability, inhibition of DC differentiation and activation, the use of autologous MSCs in cell therapy of autoimmune diseases should be submitted to attentive evaluation and treatment.

Prolonged human/sheep cellular chimerism following transplantation of human hemopoietic stem cells into the ewe celomic cavity.

We evaluated the possibility of prolonged chimerism formation in fetus and lamb, following human cord blood-selected CD133+ hemopoietic stem cell (HSC) transplantation into the celomic cavity of ewes at a pre-immune fetal age (44-45 days of pregnancy). Nineteen ewes were injected with HSC and 5 controls with a saline solution. By PCR, HLA-DQ alpha 1 and 6 human microsatellites (CODIS) were used for HSC traceability. FISH analysis was performed with 8 human DNA probes from different chromosomes, to confirm chromosomal integrity, nuclear DNA localization and donor DNA identification. Immunological staining for revealing HLA-DQ alpha 1 expression demonstrated multilineage engraftment. Both HLA-DQ alpha 1 and microsatellites were detected in different tissues of 3 available aborted fetuses, to a lesser extent in 11 lambs tested at 2-months, but not 12-months after birth. Although only 1 fetus of siblings of each sheep was injected, all siblings revealed positive engraftments. Microsatellite analysis showed evidence of human allele segregation in different tissues of individual fetuses and lambs. FISH analysis confirmed chimerism and the presence of human chromosomes. Non-detection of some human gene sequences in different chromosomes and random finding of allele segregation for some human heterozygous microsatellites were found in different tissues of individual animals. Controls born from un-transplanted ewes never revealed any human DNA sequences nor HLADQ alpha 1 expression.

Use of donor bone marrow mesenchymal stem cells for treatment of skin allograft rejection in a preclinical rat model.

Recent studies indicate that mesenchymal stem cells (MSC) exhibit a degree of immune privilege due to their ability to suppress T cell mediated responses causing tissue rejection; however, the impact of allogeneic MSC in the setting of organ transplantation has been poorly investigated so far. The aim of our study was to evaluate the effect of intravenous donor MSC infusion for clinical tolerance induction in allogeneic skin graft transplantations in rats. MSC were isolated from Wistar rats and administered in Sprague-Dawley rats receiving Wistar skin graft with or without cyclosporine A (CsA). Graft biopsies were performed at day 10 post transplantation in all experimental groups for histological and gene expression studies. Intravenous infusion with donor MSC in CsA-treated transplanted rats resulted in prolongation of skin allograft survival compared to control animals. Unexpectedly, donor MSC infusion in immunocompetent rats resulted in a faster rejection as compared to control group. Cytokine expression analysis at the site of skin graft showed that CsA treatment significantly decreased pro-inflammatory cytokines IFN-gamma and IL-2 and reduced TNF-alpha gene expression; however, the level of TNF-alpha is high in MSC-treated and not immunosuppressed rats. Results of our study in a rat tissue transplantation model demonstrated a possible immunogenic role for donor (allogeneic) MSC, confirming the need of adequate preclinical experimentation before clinical use.

Treatment of experimental injury of anal sphincters with primary surgical repair and injection of bone marrow-derived mesenchymal stem cells.

PURPOSE: Sphincter injury is a common cause of anal incontinence. Surgical repair remains the operation of choice; however, the outcome often is poor. We investigated the ability of injected bone marrow-derived mesenchymal stem cells to enhance sphincter healing after injury and primary repair in a preclinical model. METHODS: Twenty-four inbred Wistar Furth rats were divided into three groups. As a control, Group A underwent sham operation. Group B had sphincterotomy and repair of both anal sphincters plus saline injections. The study group (Group C) underwent sphincterotomy and repair followed by intrasphincteric injections of syngenic bone marrow-derived mesenchymal stem cells. A further group (Group D) of outbred Wistar rats treated with mesenchymal stem cells and immunosuppressive therapy also was evaluated. At 30 days, histologic and morphometric analysis and in vitro contractility testing was performed. RESULTS: A significant decrease of muscle tissue was observed at the site of repair after sphincter injury. However, in Groups C and D, histologic examination demonstrated new muscle fibers and morphometric analysis revealed a significantly greater muscle area fraction than in Group B (P < 0.05). Moreover, mesenchymal stem cells injection improved contractility of sphincters strips compared with Group B (P < 0.05). No significant differences were found between Groups C and D. CONCLUSIONS: In our experimental model, bone marrow-derived mesenchymal stem cells injection improved muscle regeneration and increased contractile function of anal sphincters after injury and repair. Therefore, mesenchymal stem cells may represent an attractive tool for treating anal sphincter lesions in humans. Investigations into the biologic basis of this phenomenon should increase our knowledge on underlying mechanisms involved in sphincter repair.

ATP modulates cell proliferation and elicits two different electrophysiological responses in human mesenchymal stem cells.

Bone marrow-derived human mesenchymal stem cells (hMSCs) have the potential to differentiate into several cell lines. Extracellular adenosine 5'-triphosphate (ATP) acts as a potent signaling molecule mediating cell-to-cell communication. Particular interest has been focused in recent years on the role of ATP in stem cell proliferation and differentiation. In the present work, we demonstrate that hMSCs at early stages of culture (P0-P5) spontaneously release ATP, which decreases cell proliferation. Increased hMSC proliferation is induced by the unselective P2 antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonate (PPADS) and by the selective P2Y1 antagonist 2'-deoxy-N6-methyladenosine3',5'-bisphosphate (MRS 2179). A functional role of extracellular ATP in modulating ionic conductances with the whole-cell and/or perforated patch-clamp techniques was also investigated. Exogenous ATP increased both the voltage-sensitive outward and inward currents in 47% of cells, whereas, in 31% of cells, only an increase in inward currents was found. Cells responding in this dual manner to ATP presented different resting membrane potentials. Both ATP-induced effects had varying sensitivity to the P2 antagonists PPADS and MRS 2179. Outward ATP-sensitive currents are carried by potassium ions, since they are blocked by cesium replacement and are Ca2+ -dependent because they are eliminated in the presence of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. On the basis of different electrophysiological and pharmacological characteristics, we conclude that outward ATP-sensitive currents are due to Ca2+ -dependent K+ -channel activation following stimulation of P2Y receptors, whereas inward ATP-sensitive currents are mediated by P2X receptor activation. In summary, ATP released in early life stages of hMSCs modulates their proliferation rate and likely acts as one of the early factors determining their cell fate. Disclosure of potential conflicts of interest is found at the end of this article.

Neuronal differentiation of human mesenchymal stem cells: changes in the expression of the Alzheimer's disease-related gene seladin-1.

Seladin-1 (SELective Alzheimer's Disease INdicator-1) is an anti-apoptotic gene, which is down-regulated in brain regions affected by Alzheimer's disease (AD). In addition, seladin-1 catalyzes the conversion of desmosterol into cholesterol. Disruption of cholesterol homeostasis in neurons may increase cell susceptibility to toxic agents. Because the hippocampus and the subventricular zone, which are affected in AD, are the unique regions containing stem cells with neurogenic potential in the adult brain, it might be hypothesized that this multipotent cell compartment is the predominant source of seladin-1 in normal brain. In the present study, we isolated and characterized human mesenchymal stem cells (hMSC) as a model of cells with the ability to differentiate into neurons. hMSC were then differentiated toward a neuronal phenotype (hMSC-n). These cells were thoroughly characterized and proved to be neurons, as assessed by molecular and electrophysiological evaluation. Seladin-1 expression was determined and found to be significantly reduced in hMSC-n compared to undifferentiated cells. Accordingly, the total content of cholesterol was decreased after differentiation. These original results demonstrate for the first time that seladin-1 is abundantly expressed by stem cells and appear to suggest that reduced expression in AD might be due to an altered pool of multipotent cells.

Interaction between human NK cells and bone marrow stromal cells induces NK cell triggering: role of NKp30 and NKG2D receptors.

In this study we have analyzed the interaction between in vitro cultured bone marrow stromal cells (BMSC) and NK cells. Ex vivo-isolated NK cells neoexpressed the activation Ag CD69 and released IFN-gamma and TNF-alpha upon binding with BMSC. Production of these proinflammatory cytokines was dependent on ligation of ICAM1 expressed on BMSC and its receptor LFA1 on NK cells. Furthermore, the NKp30, among natural cytotoxicity receptors, appeared to be primarily involved in triggering NK cells upon interaction with BMSC. Unexpectedly, autologous IL-2-activated NK cells killed BMSC. Again, LFA1/ICAM1 interaction plays a key role in NK/BMSC interaction; this interaction is followed by a strong intracellular calcium increase in NK cells. More importantly, NKG2D/MHC-I-related stress-inducible molecule A and/or NKG2D/UL-16 binding protein 3 engagement is responsible for the delivery of a lethal hit. It appears that HLA-I molecules do not protect BMSC from NK cell-mediated injury. Thus, NK cells, activated upon binding with BMSC, may regulate BMSC survival.

Tissue-specific gene expression in chondrocytes grown on three-dimensional hyaluronic acid scaffolds.

The re-differentiation capacities of human articular and chick embryo sternal chondrocytes were evaluated by culture on HYAFF-11 and its sulphate derivative, HYAFF-11-S, polymers derived from the benzyl esterification of hyaluronate. Initial results showed that the HYAFF-11-S material promoted the highest rate of chondrocyte proliferation. RNA isolated from human and chick embryo chondrocytes cultured in Petri dishes, HYAFF-11 or HYAFF-11-S were subjected to semi-quantitative RT-PCR analyses. Human collagen types I, II, X, human Sox9 and aggrecan, chick collagen types I, II, IX and X were analysed. Results showed that human collagen type II mRNA expression was upregulated on HYAFF-11 biomaterials. In particular, a high level of collagen type IIB expression was associated with three-dimensional culture conditions, and the HYAFF-11 material was the most supportive for human collagen type X mRNA expression. Human Sox9 mRNA levels were constantly maintained in monolayer cell culture conditions over a period of 21 days, while these were upregulated when chondrocytes were cultured on HYAFF-11 and HYAFF-11S. Furthermore, chick collagen type IIA and IIB mRNA expression was detected after only 7 days of HYAFF-11 culture. Chick collagen type IX mRNA expression decreased in scaffold cultures over time. Histochemical staining performed in engineered cartilage revealed the presence of a de novo synthesized glycosaminoglycan-rich extracellular matrix; immunohistochemistry confirmed the deposition of collagen type II. This study showed that the three-dimensional HYAFF-11 culture system is both an effective chondrocyte delivery system for the treatment of articular cartilage defects, and an excellent in vitro model for studying cartilage differentiation.