BackgroundIn vitro proliferative and differentiation potential of mesenchymal stromal cells generated from CD271 + bone marrow mononuclear cells (CD271-mesenchymal stromal cells) has been demonstrated in several earlier and recent reports. In the present study we focused, in addition to proliferative and differentiation potential, on in vitro and in vivo immunosuppressive and lymphohematopoietic engraftment-promoting potential of these mesenchymal stromal cells compared to bone marrow-derived mesenchymal stromal cells generated by plastic adherence (plastic adherence-mesenchymal stromal cells). Design and MethodsWe set up a series of experimental protocols in order to determine the phenotype of CD271-mesenchymal stromal cells, and their clonogenic, proliferative, differentiation and immunosuppressive potential. The potential of CD271-mesenchymal stromal cells to improve the engraftment of CD133 + hematopoietic stem cells at co-transplantation was evaluated in immunodeficient NOD/SCID-IL2Rg null mice. ResultsIn vitro studies demonstrated that CD271-mesenchymal stromal cells differentiate along adipogenic, osteogenic and chondrogenic lineages (trilineage potential), produce significantly higher levels of cytokines than plastic adherence-mesenchymal stromal cells, and significantly inhibit the proliferation of allogeneic T-lymphocytes in mixed lymphocyte reaction assays. Elevated levels of prostaglandin E2, but not nitric monoxide, mediated the majority of this immunosuppressive effect. In vivo studies showed that CD271-mesenchymal stromal cells promoted significantly greater lymphoid engraftment than did plastic adherence-mesenchymal stromal cells when co-transplanted with CD133 + hematopoietic stem cells at a ratio of 8:1 in immunodeficient NOD/SCID-IL2Rg null mice. They induced a 10.4-fold increase in the number of T cells, a 2.5-fold increase in the number of NK cells, and a 3.6-fold increase in the number of B cells, indicating a major qualitative difference between these two mesenchymal stromal cell populations. ConclusionsOur results indicate that CD271 antigen provides a versatile marker for prospective isolation and expansion of multipotent mesenchymal stromal cells with immunosuppressive and lymphohematopoietic engraftment-promoting properties. The co-transplantation of such cells together with hematopoietic stem cells in patients with hematologic malignancies may prove valuable in the prevention of impaired/delayed T-cell recovery and graft-versus-host disease.Key words: T-cell recovery, graft-versus-host disease, MSC.Citation: Kuçi S, Kuçi Z, Kreyenberg H, Deak E, Pütsch K, Huenecke S, Amara C, Koller S, Rettinger E, Grez M, Koehl U, Henschler R, Tonn T, von Laer D, Klingebiel T, and Bader P. CD271 antigen defines a subset of multipotent stromal cells with immunosuppressive and lymphohematopoietic engraftment-promoting properties. Haematologica. 2010;95:651-659. doi:10.3324/haematol.2009 This is an open-access paper. © F e r r a t a S t o r t i F o u n d a t i o n CD271 antigen defines a subset of m...

The CliniMACS CD34+ selection device was used for positive selection of apheresis products for autologous transplantation from 10 patients with malignant diseases and for allogeneic transplantation from 26 healthy donors. A total of 71 separations were performed. In 1 allogeneic donor, CD34+ progenitors were also isolated from bone marrow. Between 0.27 and 8.9 x 10(10) nucleated cells (median 4.9 x 10(10)) containing 0.09%-10.8% (median 0.67%) CD34+ progenitor cells were separated. After separation, a median number of 227 x 10(6) mononuclear cells (MNC) (51-524) were recovered, with a median viability of 99% (22%-100%) and a median purity of 97.0% (68.3%-99.7%) CD34+ cells. Depletion of T cells was extensive, with a median of 0.04% residual CD3+ cells (range <0.01%-0.92%). Residual CD19+ cells were between <0.01% and 17%, including CD34+CD19+ cells. Recovery of CD34+ cells was calculated according to the ISHAGE guidelines and ranged from 24% to 105% (median 71%). We conclude that with the CliniMACS device CD34+ cells with high purity and recovery can be isolated with concomitant effective T cell depletion in the allogeneic setting and with a high purging efficacy in the autologous setting.

The characterization of adipose-derived stromal/stem cells (ASCs) remains difficult due to the lack of a definitive and unique cellular marker. Therefore, a combination of markers is necessary to identify the cells. No comprehensive analysis of the immunophenotype of expanded plastic adherent ASCs has been published. Therefore, the aim of this study was to characterize the general phenotype of cultured ASCs and to further analyze cellular subsets. ASCs were isolated from lipoaspirates from patients undergoing cosmetic liposuction and cultured in standard cell culture. A comprehensive phenotype characterization was done with the BD Lyoplate™ Human Cell Surface Marker Screening Panel containing 242 antibodies and isotype controls. Cultured ASCs not only showed the characteristic expression profile of mesenchymal stem cells (MSCs), but also revealed donor-specific variability in the expression of 49 other markers. We further detected markers with a scattering in the fluorescence intensity, indicating subpopulations with different expression profiles. Therefore, a multi-color flow cytometric analysis was done after staining the cells with direct-labeled antibodies against CD73, CD90, CD105, and either CD34, CD140b, CD200, CD201, or CD36 to verify the selected subpopulations of ASCs. We detected no CD34-CD36 double-positive population, but CD34(+)-CD36(-) and CD34(-)CD36(+) subpopulations, both of which are positive for the 3 main MSC markers, CD73, CD90, and CD105. All other detected subpopulations also co-expressed the 3 main MSC markers, and therefore fulfill the minimal phenotypic criteria for the definition of cultured MSCs. Our study demonstrates the first comprehensive phenotypic characterization of ASCs and clearly highlights donor-specific variability in ASC preparations.

© Ferrata Storti Foundation IntroductionSince the first clinical trial of mesenchymal stromal cells (MSC) 9,10 Another important issue regarding the clinical application of MSCs is their culture under serum-free conditions. The majority of clinical studies have used MSCs that were expanded in media supplemented with fetal bovine serum (FBS). 1,[11][12][13][14][15] To avoid the risks associated with the use of FBS, 16 platelet lysate (PL) was proposed as a supplement to tissue culture media for MSCs. 17 Recently, several studies showed that MSCs that were expanded in PL exhibited the same efficacy as MSCs cultured in serum-containing media for the treatment of GvHD. 18-22To date, clinical studies have used MSCs that have been generated from several individual donors. Considering the aforementioned inter-donor heterogeneity and the need for a large number of "off-the-shelf" MSCs, the establishment of MSC banks appears to be an indispensable strategy for providing a continuous supply of MSCs with predictable potency. To our knowledge, there are few established MSC banks worldwide, and these MSC banks were generated by separately isolating, expanding, and freezing MSCs from up to 10 donors in FBS-containing media. [23][24][25][26] In the current study, we report for the first time the establishment of a serum-free and GMP-compliant MSC bank generated from pooled bone marrow mononuclear cells (BM-MNCs) of multiple donors as a novel strategy to circumvent donor-to-donor variability. Clinical-grade MSC endproducts (MEPs) derived from the MSC bank were thoroughly assessed for their proliferation, differentiation, and, in particular, for the allosuppressive potential in vitro. Importantly, 81 MEPs were administered as a rescue therapy to 26 pediatric patients with severe steroid-refractory aGvHD in seven transplantation centers. Safety and efficacy of MEPs was compared to MSCs generated from a single or several individual donors that have been used in the GvHDclinical studies reported thus far. Methods Generation of MSC bank and clinical-grade MEPsBone marrow was collected from 8 healthy volunteers (age 21-45 years old) after written informed consent and after the approval of the local Ethics Committee (n. 275/09). BM-MNCs were enriched from the bone marrow aspirate by using the Sepax II NeatCell process (Biosafe, Eysins, Switzerland) and frozen individually. After thawing and washing these BM-MNCs were pooled. This pool of BM-MNCs from 8 donors was used to generate MSCs over 14 days in culture. After their detachment, passage 1 mesenchymal stromal cells (MSC-P1) were washed and aliquoted into 209 cryovials (each containing 1.5x10 6 MSC-P1). Cryopreserved vials with MSC-P1 were referred to as the MSC bank.To generate clinical-grade MEPs, MSC-P1 aliquots from the MSC bank were thawed and after washing they were expanded in medium containing 10% PL till the end of passage 2. These MSCs were re-suspended in cryomedium (0.9% NaCl containing 5% HSA and 10% DMSO), distributed in cryobags (each containing 1-3x10 6 MS...

The inability to generate mesenchymal stromal cells (MSCs) of consistent potency likely is responsible for inconsistent clinical outcomes of patients with aGvHD receiving MSC products. We developed a novel MSC manufacturing protocol characterized by high in vitro potency and near-identity of individual doses, referred to as “MSC-Frankfurt am Main (MSC-FFM)”. Herein, we report outcomes of the 69 patients who have received MSC-FFM. These were 51 children and 18 adults with refractory aGvHD grade II (4%), III (36%) or IV (59%). Patients were refractory either to frontline therapy (steroids) (29%) or to steroids and 1–5 additional lines of immunosuppressants (71%) were given infusions in four weekly intervals. The day 28 overall response rate was 83%; at the last follow-up, 61% and 25% of patients were in complete or partial remission. The median follow-up was 8.1 months. Six-month estimate for cumulative incidence of non-relapse mortality was 27% (range, 16–38); leukemia relapse mortality was 2% (range, 0–5). This was associated with a superior six-month overall survival (OS) probability rate of 71% (range, 61–83), compared to the outcome of patients not treated with MSC-FFM. This novel product was effective in children and adults, suggesting that MSC-FFM represents a promising therapy for steroid refractory aGvHD.