The authors regret that references 137–180 were missing from the original article published. This caused citations within Table I to not be referenced and so Table I has been corrected and appears below, along with the missing references. The authors would like to apologise for any inconvenience caused.Table IWound healing mediators in dermal and joint tissues showing their source and major effects on cellular responsesFactorJoint tissue sourceJoint tissue repair responsesWound cell source [20–23]Wound healing responses [20–23]EGFSY[133]; OA SF[134]Chondrocyte proliferation; ion transport, decreased matrix productionP,M,FEpithelializationFGF-2SY[135–137]; AT[138]; OP[137]; OA SF[139–142]Anti-apoptotic; prochondrogenicM,EP,END,FAngiogenesisGranulation tissueECM productionTGFβ1CA[143]; SY[144]; OP[137, 145]; OA SF[47, 48]Pro-catabolic (MMP-13); chondrocyte hypertrophyP,M,EP,END,FEpithelialization,Granulation TissueFibroplasiaBMPsSY[152]; CA[146–148]; BO[149, 150]; OA SF[151]Prochondrogenic; OsteophytesSCHairfollicle formationPDGFCA[143]; SY[153, 154]; OA SF[47]Stimulates reparative responses in fibrochondrocytes; anti-hypertrophicP,M,FGranulation tissueFibroplasiaContractionVEGFCA[155–159,163]; SY[158–161], AT[138]; OA SF[47, 162]Delays reparative responses in meniscus and CAP,N,M,END,FAngiogenesisIL1βCA[143]; SY[180]; post ACLT SF[164–167]; OA SF[48, 167–170]CA and meniscal matrix degradationN,M,EPInflammationEpithelializationIL6CA[171, 172]; AT[138, 173]; PC[174]; Post ACL SF[164, 175]; OA SF[48, 169]CA matrix degradationN,M,EPInflammationEpithelializationTNFαCA[143]; SY[176]; AT[138]; Post ACLT SF[167,170,175, 177,178]; OA SF[48,168,169].CA matrix degradationN,M,EPInflammationEpithelializationAbbreviations: ACLT: Anterior cruciate ligament tear; AT: Adipose tissue; OP: Osteophyte; PC: Plasma Cells; END: endothelial cells; EP: epithelial cells; F: Fibroblasts; M: Macrophages; N: Neutrophils; P: Platelets. 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Bone marrow (BM) derived endothelial progenitor cells (EPC) can differentiate to form vasculature. It is thought that EPC have a potential role in homeostasis of the endothelium as well as repair after ischemia or other endothelial injury by inducing neovasculatization. Successful mobilization of EPC from the BM into the peripheral blood (PB) would allow for relative ease of collection and use for cell therapy.

Mesenchymal stem cells (MSC) are a rare population of cells that have the ability to form muscle, bone, cartilage, and adipose. MSC can be obtained from the bone marrow (BM). Strategies to mobilize MSC into the peripheral blood (PB) where they can be easily collected would be of therapeutic benefit but there is a lack of consensus on effective strategies to mobilize MSC.

Gruppo Italian Trapianto di Midollo Osseo (GITMO) recently proposed a new definition on "poor mobilizer" based on G-CSF (G) +/- chemotherapy based mobilization strategy (BMT (2011), 1-10). Data on using the combination of G + plerixafor (P) for mobilization (Mob) were however not utilized to formulate this proposal. Method: In this retrospective analysis, we examined the Mob kinetic, incidence and characteristics of "poor mobilizer" as proposed by GITMO in pts receving G + P for mob. Between 02/09 & 05/10, 58 consecutive pts with NHL, HD, or MM underwent Stem Cell Mobilization at our instituion using the combinaiton of G + P. Mob consisted of G-CSF 10 μg/kg SC administered daily at 6:00 am on days 1 through 4 plus plerixafor 0.24 mg/kg SC given once daily at 5:00 pm in an outpatient clinic beginning on day 4. Thirty-one (53%) pts had lymphoma (28 NHL & 3 HD) & 27 (47%) patients had MM. The median age was 57.3 years (range, 30.4-71.1). At the time of mob, all pts except 3 (5%) had chemo-responsive disease. One third of pts had received > 2 prior chemotherapy regimens and nearly half (43%) had received prior radiation therapy. Seven (12%) pts (4 NHL and 3 MM) had undergone previous mob attempts that did not include P. The median total CD34+ cell yields were 3.06 × 106 and 8.27 × 106 CD34+ cells/kg for lymphoma and myeloma pts, respectively. Apheresis yielded an adequate number of CD34+ cells in a median of 2 days (range, 1-4). The minimum CD34+ cell yield (2 × 106 CD34+ cells/kg for lymphoma pts; 4 × 106 CD34+ cells/kg for myeloma pts was achieved in 45 (78%) pts, including 23 (74%) lymphoma and 22 (81%) myeloma patients. 26 of 27 (96%) myeloma pts achieved yields of ≥2 x 106 CD34+ cells/kg. 30 (52%) pts (14 [45%] lymphoma; 16 [59%] myeloma) achieved their respective minimum CD34+ cell yields within 1 apheresis day. On the other hand, 12 (39%) pts with lymphoma and 1 (4%) pt with myeloma were identified as poor mobilizer using the criteria proposed by GITMO. Advanced disease, refractory disease, extensive BM involvement or cellularity < 30% and age > 65 did not predict for poor mobilization. We conclude that despite the use of G-CSF + P, one third of the pts with lymphoma are still "poor mobilizer" and larger study will be required to identify predictors for poor mobilization for pts using G-CSF + P as mobilization strategy. Additional measures are required to further improve mobilization efficiency for lymphoma pts.

Objective: To review the literature on modulation of chondrocyte activities in the osteoarthritic joint, and to discuss these changes in relation to established hard and soft tissue repair paradigms, with an emphasis on transforming growth factor beta (TGF beta 1)-mediated signaling which can promote either a chondrogenic or fibrogenic phenotype.Methods: Papers addressing the close relationship between repair in general, and the specific post-injury response of joint tissues are summarized. Different interpretations of the role of TGF beta 1 in the emergence of an "osteoarthritic" chondrocyte are compared and the phenotypic plasticity of "reparative" progenitor cells is examined. Lastly, emerging data on a central role for A-Disintegrin-And-Metalloproteinase-with-Thrombospondin-like-Sequences-5 (ADAMTS5) activity in modulating TGF beta 1 signaling through activin receptor-like kinase 1 (ALK1) and activin receptor-like kinase 5 (ALK5) pathways is discussed.Results: The review illustrates how a transition from ALK5-mediated fibrogenic signaling to ALK1-mediated chondrogenic signaling in joint cells represents the critical transition from a non-reparative to a reparative cell phenotype. Data from cell and in vivo studies illustrates the mechanism by which ablation of ADAMTS5 activity allows the transition to reparative chondrogenesis. Multiple large gene expression studies of normal and osteoarthritis (OA) human cartilages (CAs) also support an important role for TGF beta 1-mediated pro-fibrogenic activities during disease progression.Conclusions: We conclude that progressive articular CA damage in post-injury OA results primarily from biomechanical, cell biologic and mediator changes that promote a fibroblastic phenotype in joint cells. Since ADAMTS5 and TGF beta 1 appear to control this process, agents which interfere with their activities may not only enhance endogenous CA repair in vivo, but also improve the properties of tissue-engineered CA for implantation. (C) 2011 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

6588 Background: A major challenge in developing treatment regimens for AML is identifying strategies to prevent disease relapse. Advances in understanding the biology of AML leukemogenesis have revealed that schedule and combination strategies for treatment influence outcome. This study examines the in vitro effect of current chemotherapeutic drugs cytarabine, mitoxantrone (synthetic anthracynedione) and the active form of oral drug sapacitabine, 2'-C-Cyano-2'-deoxy-1-β-d-arabino-pentofuranosylcytosine (CNDAC) on leukemic cells from 5 AML patients. METHODS Untreated AML bone marrow (BM) and peripheral blood (PB) mononuclear cells (MNC) from 5 patients were treated with Ara-C (1-100μM), CNDAC (1-100μM) and Mitoxantrone (0.005 - 0.5μM) for 4 days. Total WBC counts ranged from 27.06 - 93.05 K/µL with 58 - 99% CD34+ cells. BM MNC's were exposed to drugs in a co-culture system using the mouse stromal cell line, M2-10B4. PB MNC's were drug treated in suspension. Post treatment, both BM and PB cells were replated on M2-10B4 stromal layers. Non-adherent cells were assessed for overall viability post-treatment and at 3, 7 and 31 days of culture following drug treatment. RESULTS In the PB, after 3 days post drug removal, the total cell survival was significantly lower for cells treated with 1µM CNDAC or 0.005µM Mitoxantrone compared to 1µM cytarabine (p<0.05, n=5). Although a similar trend was seen with BM cells, it did not reach significance. In both the BM and PB, survival of cells treated with 1µM CNDAC or 0.005µM mitoxantrone over the 35 day culture period was significantly less than untreated cells (p<0.05, n=5). The survival of 1µM cytarabine treated cells was not significantly lower. CONCLUSIONS CNDAC and mitoxantrone have a longer in vitro impact on the survival of PB cells than cytarabine. A subset of similar cells in the BM was most likely protected by the stroma in the BM co-culture system, thus lessening the impact. However, as seen by the similar profiles in PB and BM, both CNDAC and mitoxantrone appear to have a greater overall effect on cell survival than cytarabine. Due to the effectiveness and ease of administration of CNDAC, it may complement cytarabine and mitoxantrone and influence optimal scheduling in treatment of AML.

Abstract Background: The impact of mesenchymal stem cells (MSCs) on breast cancer (BC) progression and growth remains controversial. Some studies using xenograft BC models in nude mice suggest that MSCs stimulate BC metastases, whereas other studies in syngeneic rat BC models suggest that MSCs suppress BC development and growth. In addition, whether MSCs have a role in BC initiation has not been tested. The objective of this study was to determine if bone marrow-derived MSCs affect BC initiation and progression in vitro and in clinically relevant somatic and synegeneic BC mouse models. Materials and Methods: MSCs were isolated from bone marrows of FVB wild-type mice, cultured, and characterized for their potential to differentiate into adipocytes and express flow-cytometric cell surface markers. MSC-conditioned medium (CM) was used to culture RCAS-Neu and RCAS-PyMT BC cell lines, derived from TVA-transgenic mice infected with an avian retroviral vector encoding Neu or polyoma middle T antigen (PyMT). Cell proliferation was analyzed with CellTiter 96 proliferation assay and 5-bromo-2-deoxyuridine labeling. The effect of RCAS-Neu and RCAS-PyMT cells and their CM on MSC migration was determined with Boyden chamber migration assay. In a somatic BC model, TVA-transgenic mice expressing the receptor for an avian retrovirus vector, RCAS, were infected with RCAS-PyMT vector by intraductal injection and treated with MSC (2x106cells/mouse) by i.v. injection. Mice were observed for BC development by palpation. In a syngeneic BC model, RCAS-Neu BC cells were co-implanted with MSCs (5x105/gland) at the ratios 1:0, 1:0.2, or 1:1 into the fat pad of FVB female mice. BC growth was monitored for 9 weeks. Results: CM from MSC did not significantly affect the proliferation of RCAS-Neu and RCAS-PyMT cells. However, RCAS-Neu and RCAS-PyMT cells and their CM induced morphologic changes in MSC and dramatically increased their motility. In somatic model, MSCs had no effect on BC initiation or growth with the mean tumor latency 27.5±7.5 days in MSC-treated mice and 29±5.5 days in control mice treated with PBS. In syngeneic BC model, there was no significant difference in the growth of RCAS-Neu alone or RCAS-Neu cells co-implanted with MSCs. Since BC in these models does not metastasize to distant organs, it could not be determined whether MSCs affect BC metastases. Discussion: Our results demonstrated that BC cell lines and their CM are able to induce MSCs migration and possibly differentiation. However, MSCs had no effect on BC initiation in a somatic BC model and on tumor growth in a syngeneic BC model. It is possible that the number of MSCs and schedule of MSC injection were not optimized or strong PyMT oncogene rapidly induced BC and overcame the effect of MSCs on BC formation. Experiments are ongoing to determine if multiple administrations of MSCs affect BC development induced by PyMT and Neu oncogenes. Lack of effect of MSCs in BC initiation and progression, if confirmed, will suggest that MSCs are safe for delivering novel antitumor agents for BC treatment. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-05-04.

Hematopoietic stem cells (HSC) are routinely obtained from bone marrow, mobilized peripheral blood, and umbilical cord blood (CB). Adult bone marrow has been traditionally utilized as the preferred source of mesenchymal stem cells (MSC) to provide the stromal component necessary to fulfill the requirement of the stem cell niche, thereby preserving the microenvironment for HSC function. Bone marrow-derived MSC (BM-MSC) have been shown to maintain the growth of CB HSC ex vivo and promote engraftment into immunodeficient mice. However, the use of a BM-MSC as a feeder layer to support ex vivo culture and/or hematopoietic stem cell transplantation (HSCT) of CB may not be the most ideal scenario for the clinical transplant setting. Recently, MSC obtained from the Wharton's Jelly of the umbilical cord (UC-MSC) were shown to have mesenchymal stem and/or progenitor cell potential as well as secrete several important cytokines and growth factors. Having shown in our lab that UC-MSC exhibit important functional characteristics of stromal cells, such as the ability to support the maintenance of CB CD34+ cells in long term culture-initiating cell (LTC-IC) assays, we further hypothesized that UC-MSC are able to promote engraftment of CB. To test this hypothesis, we evaluated the effect of UC-MSC co-transplantation in the Non-Obese Diabetic/Severe Combined Immunodeficient /IL-2 Receptor γnull (NOD/SCID/IL2Rγnull) mouse model of HSCT. We report here that co-transplantation of CB with UC-MSC resulted in an increase in the percentage of short term repopulating cells in the bone marrow of sub-lethally irradiated mice three weeks post transplant. Specifically, increases in the percentage of CD45+ cells from 5.0±1.0% to 7.8±0.8% and from 1.1±0.5% to 11.1±1.7% were noted for CD34+ and MNC recipient mice respectively. In addition, statistically significant increases in the percentage of CD34+, CD34+CD38-, CD34+CD38+, CD33+, CD61+, and CD14+ cells were also noted in both CD34+ and MNC recipient mice (p ≤ 0.05, n = 3). No significant change in CD19+ cells was noted in any treatment group. This data suggests that UC-MSC have the ability to enhance short term myeloid reconstitution. It may therefore be possible to develop UC-MSC methodologies to both improve ex vivo CB culture and increase transplant efficiency. Additionally, it may be preferred that CB HSC and MSC be genetically identical or from an HLA-matched or unmatched non-adult MSC tissue source.

Introduction: Through the use of CD26 inhibitors and CD26 deficient mice (CD26-/-), we have previously generated data suggesting that suppression of CD26/DPPIV activity on the transplant donor cell population could potentially be utilized clinically as a method of increasing transplant efficiency. However, the clinical importance of the transplant recipient should not to be overlooked. We therefore investigated whether inhibition or loss of CD26 activity in the recipient would have an effect on hematopoietic stem cell transplantation utilizing an in vivo congenic mouse model of transplantation. Methods: The short-term homing and long-term engraftment of BoyJ donor cells (expressing CD45.1+) into lethally irradiated control C57BL/6, CD26 inhibitor (Diprotin A) treated C57BL/6, or CD26-/- mice (expressing CD45.2+) was monitored by flow cytometric analysis of the bone marrow and peripheral blood at 24 hours and 6 months post-transplant. Results: Twenty-four hours post-transplant of 20 × 106 BoyJ mononuclear cells, we observed 8.85 ± 0.58%, 10.69 ± 1.01%, and 12.45 ± 1.33% donor derived Sca-1+lin- cells in the bone marrow of recipient mice for control, Diprotin A treated, and CD26-/- recipient mice respectively. As compared to control mice, this represents a 20.8% increase (p = 0.01) with CD26 inhibitor treatment and a 40.7% increase (p ≤ 0.05) resulting from the use of a CD26-/- recipient in short-term homing (N = 5 mice per group). Six months post-transplant of 1 × 105 BoyJ mononuclear cells, we observed 39.90 ± 4.38%, 70.22 ± 3.72%, and 92.51 ± 1.04% donor contribution to hematopoiesis in the peripheral blood of control, Diprotin A treated, and CD26-/- recipient mice respectively. This represents a 76.0% increase (p ≤ 0.01) with CD26 inhibitor treatment and a 131.9% increase (p ≤ 0.01) as a result of the CD26-/- recipient in long-term engraftment as compared to control recipient mice (N = 14 mice per group). Conclusions: These results provide pre-clinical evidence of the importance of CD26 expression within the transplant recipient with regard to regulating hematopoietic stem cell homing and engraftment. Our results also support the potential use of CD26 inhibitors to treat transplant patients during hematopoietic stem cell transplantation as a method of improving transplant efficiency.

Hematopoietic growth factors (HGF) G-CSF and GM-CSF have been utilized widely to facilitate mobilization of progenitor cells that can be used to support high dose CT. Recently long-acting HGF neulasta (pegfilgrastim) and aranesp (darbepoetin alfa) were developed to reduce the frequency of administration. While these agents are effective in reducing CT-induced neutropenia and anemia similar to their parent compounds, very little is known about their efficiency in mobilizing progenitor cells. The purpose of this study was to evaluate biologic effects of these agents, used in combination with CT, on progenitor cells. Chemo-naive sarcoma patients receiving adriamycin and ifosfamide (AI) were treated once per cycle with aranesp (500 mcg) SC prior to initiating CT (day 0) and neulasta (6 mg) SC after completion of CT (day 4). BM and peripheral blood (PB) samples were studied at the baseline and around day 14 (at the time of WBC recovery) for progenitors and mediators of response. The treatment was associated with a significant increase in PB CD 34 + cells (median increase 36-fold, p=0.005) and marked mobilization (p=0.003) of CFU-GM (24-fold), BFU-E (22-fold), and CFU-GEMM (62-fold) (n=14). To better understand the biology and nature of response, we examined BM before and at the time of mobilization (n=12). There was an expansion of multi-lineage BM progenitors (p=0.06) and CD 34+ cells (P=0.001). BM exam at the time of recovery showed increased cellularity (2-fold) with increased granulopoietic elements. An increased expression of MMP-9 but unchanged expression of TIMP-1 was observed by Immunohistochemistry (IHC). c-kit ligand level by Elisa was decreased in the BM supernatant. In addition, phospho c-kit (phospho site 568) was increased in the myeloid and erythroid precursors by IHC but phospho site 823 was unaltered, indicating the specificity of activation of the downstream pathway in response to c-kit ligand-receptor activation, possibly leading to expansion of progenitor cells. Interestingly, expression of CXCR4 at the protein level (flow cytometry and western blot) and RNA level (RT-PCR) was decreased (p

We isolated and characterized a novel AML1 (also termed Runx1) fusion transcript from a radiation-associated acute myeloid leukemia with a t(19;21). This fusion transcript, termed AML1-AMPl9, was joined out of frame, resulting in a truncated AML1 protein that inhibits activation of AML1 target promoters. It is now becoming clear that truncations of AMLl are more common in leukemia than previously thought. To analyze the effect of truncated AML1 species on myeloid differentiation and proliferation, AML1-AMPl9 was retrovirally transduced into the IL-3-dependent 32D cells. 32D cells over-expressing AML1-AMPl9 failed to differentiate normally when stimulated with G-CSF, but continued to proliferate and maintained a primitive phenotype. However, AML1-AMPl9 did not transform the cells to cytokine independence, implying that for full transformation of a myeloid progenitor by truncated AML1 another genetic lesion is required.