ALBERT

Description: Background and objective Clinical trials have confirmed that CAR-T treatment has become one of the important treatments for many relapse and refractory hematological tumors. CRS is a high incidence of adverse events in CAR-T treatment. A deeply understanding of the characteristics and related risk factors of CRS is important for the effective management of CRS. The characteristics and risk factors of CRS occurred in 142 patients during CAR-T treatment were analyzed in detail to provide a direct and reliable basis for clinicians to diagnose and predict CRS. Patients and Methods We collected 142 patients with different hematologic malignancies who underwent CAR-T treatment from January 2015 to December 2018. All patients were screened according to the inclusion and exclusion criteria at the time of trial design. Patients received Fludarabine and cyclophosphamide to remove T cells before infusion of CAR-T. Infused CAR-T cells include anti-CD19 CAR-T, anti-BCMA CAR-T and anti-CD20 CAR-T. Glucocorticoids were not used to prevent allergic reactions prior to infusion. Adverse events were assessed using the CRS evaluation criteria proposed by Lee et al. and the Common Terminology Criteria for Adverse Events (CTCAEs, version 4.0) criteria. Results: 1.General characteristics of patients and CRS Of all patients, 87 (61.3%) were male and 55 (38.7%) were female; the median age was 45 (IRQ = 24-59). The incidence of CRS in ALL, lymphoma and myeloma were: 82%, 90% and 90%, respectively. Fever is the main first symptom of CRS. The median time to onset of fever is 3 days for ALL (IRQ 0-7 days), 1 day for lymphoma (IRQ 0-5 days), and 8.5 days for MM (1.75-12.75 days). There was a statistically significant difference between MM and ALL (p=0.0044) or MM and lymphoma (p=0.0002). The duration of fever was different between CRS grade 1-2 and grade 3-5 (P=0.007), but there was no difference between ALL, lymphoma, and MM [3 (0-7 days) vs 5 (3-8 days) vs 4(3-8 days)]. Levels of serum ferritin, IL-6, and CRP were consistent with CRS, but there was no significant difference in different time points after CAR-T infusion except for IL-6 levels of ALL patients between days 7 and 10. However, the peak concentration of ferritin, IL-6, and CRP is different from the baseline. 2.General risk factors for CRS In the univariate analysis, the maximum concentration of serum IL-6 (p=0.000) and CRP (p=0.001) were different between CRS3-5, CRS1-2, and patients without CRS. For further analysis, the IL-6 was statistically different between CRS3-5 and CRS1-2 (p=0.03), CRS3-5 and Non-CRS (p=0.00), or CRS1-2 and Non-CRS (p=0.00). The CRP was statistically different between CRS3-5 and Non-CRS (p=0.00), CRS1-2 and Non-CRS (p=0.01). There were no differences in age, gender, pre-transplantation, type of disease, dose of CAR-T cells, and costimulatory molecules. In multivariate analysis, disease (ALL vs MM (p=0.043), ALL vs MM (p=0.021)), costimulatory molecules (p=0.022), peak concentration of IL-6 (p=0.000) and CRP (p=0.001) are independent risk factors. 3.Specific risk factors For ALL patients, in the univariate analysis, the number of lymphoblasts in the bone marrow before FC deplete lymphocytes chemotherapy was different between CRS3-5 and Non-CRS of patients with CRS3-5, CRS1-2, and patients without CRS (p=0.00). There was no significant difference in the number of lymphoblasts after FC deplete lymphocytes chemotherapy, CAR species, and costimulatory molecules. In the multivariate analysis, hematopoietic stem cell transplantation before CAR-T treatment, the numbers of lymphoblasts in the bone marrow before FC deplete lymphocytes chemotherapy, and the CAR species were independent risk factors. For patients with lymphoma, there was no difference in IPI scores, clinical staging, and infused number of CAR-T cells. There were no significant differences in β2-MG, light chain type, myeloma cell number, and ISS stage in patients with MM. Conclusion: The occurrence of CRS in different B-cell tumors has its own characteristics. Compared with ALL and lymphoma, the incidence of severe CRS in MM patients is lower and occurs later. 2. The risk factors of CRS in different B-cell tumors are different. Individualized treatment of is needed in clinical practice. Figure 1 Characteristics of CRS (A. the incidence of CRS, B. days of fever onset after CAR-T infusion, C. duration of fever, D. peak temperature of fever) Figure 1 Disclosures No relevant conflicts of interest to declare.

Description: Key Points Endogenous sVEGFR-3 that is expressed by the cornea binds and sequesters VEGF-C and is critical for corneal alymphaticity. sVEGFR-3 overexpression enhances murine corneal graft transplant survival 5-fold by blocking lymphangiogenesis and hemangiogenesis.

Description: Key Points There is a role for the posttranslational modification, neddylation, in regulation of immune responses mediated by dendritic cells. A role for neddylation in NF-κB signaling in dendritic cells was identified.

Description: Background: Pain is one of the major comorbidities of sickle cell disease (SCD), which largely remains reliant on opioid use for analgesia. Side effects of opioids including, but not limited to fear of addiction, constipation, pruritus and opioid-induced hyperalgesia warrant the need for analgesic therapies devoid of side effects. Non-pharmacological strategies including acupuncture have been effective in pain treatment. A retrospective analysis (n=24 patients) showed that acupuncture reduced pain in a majority (75%) of SCD patients (Lu K et al., Clin J Pain. 2014). In a mouse model of SCD, electroacupuncture (EA) on conscious free-moving mice led to variable analgesic response ranging from high- (nociceptive threshold increase 〉200%), moderate- (threshold between 100~200%) to non-responders (threshold increase ≤100%) (Wang Y et al., Sci Rep. 2016). Substance P (SP), a proinflammatory vasoactive neuropeptide in the periphery and centrally and spinal activated p38 mitogen activated protein kinase (MAPK), critical mediators of chronic pain were significantly increased in sickle mice with moderate or no response to EA analgesia. Increased circulating SP has been reported in SCD patients at steady state and during chronic pain. We hypothesize that chronic pain in moderate- and non-responders is due to central sensitization mediated by SP-induced p38 MAPK phosphorylation; and that inhibiting the effect of SP and/or downstream p38 MAPK signaling would improve response to EA in moderate and non-responsive sickle mice. Methods: HbSS-BERK sickle mice expressing human sickle hemoglobin without any treatment and those showing moderate- (threshold between 100~200%) and no-response (threshold increase ≤100%); and HbAA-BERK control mice that express normal human hemoglobin A were used. All groups included mice of both genders at 5-7 months of age and were treated daily with 10 mg/kg, i.p. netupitant (antagonist of neurokinin 1 receptor, a receptor for SP), or SB203580, a p38MAPK inhibitor, with or without four sequential EA treatments (every 3rd day, frequency: 4 or 10 Hz, pulse width: 100 microsecond, duration: 30 min) at acupoint GB30. Hyperalgesia was evaluated daily before starting the inhibitor/EA treatment (baseline, BL) and after treatments throughout 12 days by determining the sensitivity to mechanical-, thermal- and deep tissue-stimuli using von Frey filaments, Hargreaves test, cold plate and grip force, respectively. Results: Sickle mice showing no- or moderate responsive to EA did not demonstrate a significant effect of netupitant or SB203580 without EA on hyperalgesia. However, co-treatment with netupitant and EA reduced mechanical, thermal and deep tissue hyperalgesia through the entire treatment, reaching significance at day 9 and/or day 12. Co-treatment with netupitant enhanced analgesia of EA by significantly decreasing mechanical hyperalgesia (p

Description: Weibel-Palade bodies (WPBs) are elongated secretory granules of endothelial cells that are packed with tubules composed of von Willebrand factor (VWF), a multimeric protein required for hemostasis. Disruption of tubular packing prevents the orderly secretion of VWF multimers and blocks the subsequent binding of platelets. The cigar-like shape and tubular cross section of WPBs are conserved in all vertebrates, but little is known about how VWF specifies this packing arrangement. Starting from recombinant 82 kDa VWF propeptide (domains D1D2) and 114 kDa disulfide-bonded D’D3 dimer, we now have assembled tubules reversibly in vitro with the same dimensions as VWF tubules in WPBs. Assembly was induced at pH 6.2, reversed at pH 7.4, and required Ca2+. Recombinant D’D3 dimers did not self-associate at pH 7.4 or pH 6.2, with or without Ca2+. Without Ca2+, VWF propeptide did not bind to D’D3 dimers. At pH 7.4, with Ca2+, VWF propeptide formed noncovalent 160 kDa dimers and, when mixed with D’D3 dimers, assembled a 280 kDa complex of two propeptides and one D’D3 dimer as shown by gel filtration chromatography and multi-angle light scattering. Lowering the pH to 6.2 caused the formation of 〉3 MDa aggregates with the same stoichiometry, which dissociated upon adding EDTA or raising the pH to 7.4. Quick-freeze deep-etch EM showed that the large aggregates are hollow right-handed tubular helices. The iterative helical real space reconstruction method was used to make 3D reconstructions of the tubules at 22 Å resolution from negative stain EM images (Figure, left). Tubules consist of a right-handed helix with axial rise of 26.2 Å and twist of 85.6 degrees per subunit, or 4.2 subunits per 11 nm turn. The dimensions (outside diameter 25 nm, inside diameter 12 nm) are similar to those of tubules in WPBs in thin sections of endothelial cells by transmission EM (Figure, right and its insert). Each subunit contains one D’D3 dimer flanked by two D1D2 propeptides (Figure, center). Each D’D3 dimer makes a total of six contacts with D1D2 domains. Each D1D2 propeptide makes three contacts with D’D3 and just one end-to-end homotypic contact. The spatial arrangement of these building blocks and inter-domain contacts in tubules suggest a model by which decreasing pH along the secretory pathway coordinates the formation of intersubunit disulfide bonds with the tubular packaging of VWF multimers. Within the WPB, Ca2+-dependent and pH-dependent binding of D1D2 to D’D3 domains stabilizes the packing of VWF multimers into tubules, which behave as constrained springs. Upon secretion, the increased pH weakens these constraints and permits the helical tubules to unfurl into flowing blood without tangling. Figure Figure

Description: Background Chronic myeloid leukemia (CML) stem cells are inherently insensitive to tyrosine-kinase inhibitors (TKI). However, an important minority of CML patients was shown to discontinue TKI without experiencing molecular relapse. Underlying mechanisms are currently unknown. Plasmacytoid dendritic cells (pDCs) are critical regulators of immune responses. Following activation, pDC upregulate MHC-class II and other DC activation markers such as CD86 (also known as B7.2). CD86 is a co-stimulatory molecule during T-cell activation, but also ligand of the inhibitory immune checkpoint receptor CTLA-4, which counteracts T-cell activation. The origin and function of pDC in CML biology is unknown. Within a sub-study of the EUROSKI TKI discontinuation trial we prospectively tested the hypothesis that pDC counts and CD86 expression status govern relapse risk following TKI discontinuation. Methods: Using flow cytometry, cell sorting and fluorescence in situ hybridization (FISH), CD86 expression and BCR-ABL status were analyzed in PDCA-2+/CD123+ peripheral blood (pB) pDC of untreated CML patients (CML pDC), normal donors and 123 patients, who had stopped TKI therapy in deep molecular remission within the international EUROSKI study (EUDRACT 2011-000440-22). All 123 EUROSKI patients had given written informed consent to participate in the immunological sub-study of the EUROSKI trial. Fresh samples from 19 EUROSKI centers in Germany were centrally analyzed prior, as well as 1, 2, 3 and 6 months after TKI discontinuation. PB CD86+ pDC counts were calculated per 105 cells in the lymphocyte gate. Decision trees and 10-fold cross validation were employed to establish relapse prediction accuracy for this value. Results CML pDC were BCR-ABL-FISH positive (median: 81%; range, 57 to 100%). In contrast, the proportion of CD86+ CML pDC varied substantially (median: 25.9%, range 3.2% to 82.4%), suggesting that CD86 expression on CML pDC was not a direct consequence of oncogenic BCR-ABL signaling. This was confirmed experimentally in a murine CML model. In contrast to CML pDC, remission pDC were always BCR-ABL FISH negative (n=10), but still displayed a comparable high proportion of CD86 positive pDC (median: 21%; range, 2.2% to 62%). In contrast, normal donor pDC were rarely CD86 positive (median: 6.8%; range, 4.2% to 17%), reinforcing the aberrant, and BCR-ABL-independent nature of CD86 expression on CML and remission pDC. As a result, healthy donors displayed only between 26 to 84 CD86+ pDC per 105 lymphocytes, whereas EUROSKI remission patients exhibited between 6 to 309 CD86+ pDC per 105 lymphocytes. Based on the important role of CD86 as a high affinity ligand of the inhibitory immune checkpoint receptor CTLA-4, we next asked, whether CD86+ pDC counts are associated with relapse risk after TKI discontinuation. Strikingly, statistical models suggested that a CD86+ pDC count below or above 95 CD86+ pDC/105 lymphocytes optimally separated two relapse categories of EUROSKI patients. Whereas relapse free survival (RFS) (loss of MMR) for patients with more than 95 CD86+ pDC/105 lymphocytes was 30% (n=32), RFS was 69% for patients (n=91) with less than 95 CD86+ pDC/105 lymphocytes (p

Description: Sickle cell disease (SCD) is characterized by chronic hemolysis, inflammation, vascular dysfunction, and pain. Earlier we showed that mast cell activation contributes to neuroinflammation and pain and is accompanied by increased toll-like receptor 4 (TLR4) expression on mast cells (Vincent et al., Blood 2013), and that genetic deletion of TLR4 ameliorates neurogenic inflammation and hyperalgesia in HbSS-BERK sickle mice. Several other studies have shown increased TLR4 expression in peripheral system and its involvement in sickle pathobiology. We propose that free heme, due to hemolysis, activates TLR4 in the central nervous system in addition to peripheral activation, which further exacerbates neuroinflammation and hyperalgesia. Spinal cords of HbSS-BERK sickle mice show 3-fold mRNA transcripts for TLR4 and a 2-fold increase in hemin as compared to the spinal cords of HbAA-BERK control mice. Therefore, targeting TLR4 with pharmacological inhibitors may provide a therapeutic approach to attenuate peripheral and central inflammation and hyperalgesia. In the present study we examined the potential of pharmacological inhibition of mast cell activation, neuroinflammation and hyperalgesia in HbSS-BERK sickle mice with TLR4 inhibitor, TAK242. Sickle mice were administrated intravenously with TLR4 inhibitor TAK242 (1 mg/kg body weight/day) for 5 days. Sensory testing was performed at baseline at recruitment and periodically during the 5-day treatment and for another 8 days after concluding the treatment to evaluate mechanical hyperalgesia with von Frey filaments, thermal hyperalgesia in response to heat/cold and grip force for musculoskeletal/deep tissue hyperalgesia. Following the 5-day treatment with TAK242, release of cytokines, tryptase (marker of mast cell activation) and substance P released from skin biopsies and spinal cords were analyzed by ELISA. TAK242 significantly decreased the release of tryptase (TAK242: 5.178 ± 0.7613 pg/ml vs vehicle: 8.801 ± 0.9403 pg/ml, p = 0.0181), substance P (TAK242: 11.56 ± 1.945 pg/ml vs vehicle: 25.51 ± 4.283 pg/ml, p = 0.018), and IL-6 (TAK242: 15.59 ± 0.4541 pg/ml vs vehicle: 29.74 ± 0.8249 pg/ml, p = 0.0045) from skin biopsies, suggesting that TAK242 reduced SCD-induced mast cell activation and inflammation. TAK242 also significantly decreased substance P (TAK242: 0.7198 ± 0.0587 pg/mg vs vehicle: 0.931 ± 0.0676 pg/mg, p = 0.0462) and phosphorylation of p38/MAPK (p = 0.0184) in the spinal cord, as well as dorsal cutaneous blood flow (TAK242: 6.392 ± 0.3857 PU vs vehicle: 12.32 ± 0.5575 PU, p 〈 0.0001), indicating that TAK242 ameliorated SCD-evoked central and peripheral activation of inflammation and nociceptive mechanisms. Furthermore, TAK242 administration gradually reduced the mechanical, deep tissue, and thermal hyperalgesia upto 5-day treatment (p 〈 0.01, vs vehicle HbSS). However, discontinuation of treatment led to a gradual increase in hyperalgesia observed upto day-8 post-treatment. TAK242 also significantly decreased acute pain induced by hypoxia/reoxygenation and accelerated recovery from injury of hypoxia/reoxygenation. These data reveal the significant therapeutic effect of pharmacological inhibition of TLR4 on inflammation and hyperalgesia in sickle mice. Therapies targeting TLR4 inhibition may be potentially beneficial in ameliorating sickle pathobiology and pain. Disclosures No relevant conflicts of interest to declare.

Description: Background: Although an internal tandem duplication (ITD) of the Fms-like receptor tyrosine kinase 3 receptor (FLT3) confers a very poor prognosis in acute myeloid leukemia (AML), it is insufficient to cause AML, suggesting important cooperating genetic events. NFATc1 is a member of the nuclear factor of activated T-cells (NFAT) transcription factor family, whose activation is dependent on nuclear translocation. NFATc1 is well known for its central role in regulating T-cell development and function, but was also shown to contribute to neoplastic transformation in diverse types of cancers. We have recently demonstrated that NFATc1 is overexpressed in primary FLT3-ITD+ AML causing resistance to the FLT3-kinase inhibitor sorafenib in vitro. Here we asked, whether NFATc1 induces AML transformation and drug resistance when expressed in the context of FLT3-ITD+ in vivo. Methods: Using the stem cell like (SCL)-promoter, Cre-recombinase inducible expression of a constitutively nuclear NFATc1 protein (cnNFATc1) was targeted to the early hematopoietic stem cell compartment. The SCL-Cre/cnNFATc1 mice were subsequently crossed with transgenic FLT3-ITD mice to yield Scl-Cre+/-/cnNFATc1+/+/FLT3-ITD+/+ mice (FCN+/+), which co-express cnNFAT and FLT3-ITD in the stem cell compartment. Results: Whereas FLT3-ITD mice developed a non-lethal, mild myeloproliferative disease, co-expression of FLT3-ITD with cnNFATc1 led to rapidly fatal AML. The median survival of FCN mice was only four months (range, 2 to 8 ). In median, FCN mice had 15-fold (range, 10 to 20) increased white blood cell count, a high proportion of circulating peripheral blasts, severe anemia and thrombocytopenia. There was also a significant B-cell developmental block. As opposed to F+/+ animals, FCN+/+ mice revealed a severe spleno- and hepatomegaly secondary to a gross leukemic infiltration, which disrupted the normal anatomical architecture of the involved organs. Fluorescence activating cell sorting and colony forming unit (CFU) assays demonstrated that cnNFATc1, when expressed in the context of FLT3-ITD, leads to a significant expansion of the lin-Sca+c-kit+ (LSK) stem cell-, progenitor cell (LK)-, the Gr-1-/CD11b+ monocytic and Gr-1low/CD11b+ immature myeloid compartments in bone marrow and spleen. FCN+/+-AML was polyclonal, and re-transplantable in secondary wild-type recipient mice. In vivo, cnNFATc1 caused not only potent FLT3-ITD inhibitor resistance to sorafenib and to the more FLT3-ITD-selective compound quizartinib, but also to chemotherapy. Comparative mRNA-sequencing of sorted LK and LSK compartments in wild-type, F+/+, C+/- N+/+, and FCN+/+ mice will reveal the genetic basis of the biological cooperativity between NFATc1 and FLT3-ITD in stem and progenitor cell compartments. Consistent with the murine data, a data set of AML patients (n=163) revealed that NFATc1 overexpression alone or when combined with FLT3-overexpression was associated with a significantly decreased overall survival (hazard ratio [HR] 1.91, CI 1.29-2.18, p=0.001 versus HR 2.57, CI 1.62-4.08, p

Description: Introduction: TBLR1-RARα is the tenth fusion gene of acute promyelocytic leukemia (APL) first identified in a rare case of APL with t(3;17)(q26;q21) chromosomal translocation in our previous study. The characteristics of its basic structure and functions had been clarified in our previous study. In this study, we successfully established a novel TBLR1-RARα leukemia mouse model (TR mouse) which fully recapitulated the most relevant features of human APLs. The therapeutic effects of retinoic acid (ATRA), arsenic trioxide (As2O3), cytarabine (Ara-C) and histone deacetylase inhibitors (HDACi) on TR mice were examined. The differentially expressed genes (DEGs) between TR mice and normal mice were compared to explore the possible mechanisms and better therapeutic targets for this kind of APL. Methods: pMSCV-TBLR1-RARα-Flag-IRES-GFP (MSCV-TR) and pMSCV-IRES-GFP (vehicle) retroviral plasmids were constructed and transfected 293T packaging cells to produce retroviruses. Lin- cells from C57BL/6 mice bone marrow were purified and infected with MSCV-TR and vehicle retroviral supernatant. For in vitro assay, the GFP+ lin- cells sorted and incubated with or without different concentrations of ATRA were analyzed for the differentiation and proliferation capacity by cell morphology, myeloid markers (CD11b and GR-1) and colony formation assay. For the in vivo experiment, GFP+ lin- cells transfected with indicated retroviral vectors were injected intravenously to lethally irradiated C57BL/6 mice to establish an APL mouse model. Cell surface markers were analyzed by flow cytometry. In treatment assays, GFP+ spleen cells from TR leukemia mice were injected intravenously into recipient mice. The mice were randomly separated into groups and received different treatment with ATRA, As2O3, As2O3 in combination with ATRA, Ara-C, Ara-C in combination with ATRA, chidamide and NL101, respectively. The percentage of GFP+ cells in peripheral blood and body weight were measured dynamically. The survival time of every group was recorded and compared. RNA-seq assay was used to identify DEGs between TR mice and normal mice. Results: In vitro assays indicated that TBLR1-RARα could either block the differentiation of HSCs at a relatively early stage or enhanced the clonogenic potential of cells. The TBLR1-RARα leukemia mouse model was successfully established. During the ten-month observational period, 3 out of 15 mice transplanted with TBLR1-RARα expressing cells developed an APL-like disease. Development of leukemia was not observed in any of the mice in control group. All the leukemia mice had a body weight loss as well as splenomegaly and hepatomegaly. The phenotype analysis revealed that the progenitor markers Sca-1, CD34 and C-kit were positive, the myeloid lineage markers Gr-1 and CD11b were also positive, erythroid lineage marker Ter119 was weekly positive, but the lymphatic lineage marker B220, CD3,CD4 and CD8 were all negative. TR mice treated with 1.5-2.5 mg/kg ATRA alone or together with 2.0 mg/kg As2O3 didn't survive longer than that of control group, although in vitro differentiation experiment showed that the leukemia cells were sensitive to ATRA. Leukemic mice receiving Ara-C treatment had a much longer survive time. Surprisingly, HDAC inhibitors (12.5 and 25 mg/kg chidamide and 30 mg/kg NL-101) could significantly prolong the survival time of TR mice. Thousands of DEGs had been identified between TR mice and wild type mice, which were widely involved in multiple pathways and participated in various biological functions. Conclusion: The TBLR1-RARα leukemia mouse model was successfully established for the first time, and its main characteristics were clarified. Although the leukemia cells were sensitive to ATRA in vitro, TR mice didn't benefit from ATRA or As2O3 treatment in vivo. Besides Ara-C, HDAC inhibitors, such as chidamide and NL-101 exhibited potency therapeutic values for TR mice, which provided a new strategy for this kind of refractory APL. What' more, lots of genes that might be related with the process of leukemogenesis and new therapeutic targets for TR leukemia were identified. This model would serve as a versatile tool to study the mechanisms of leukemogenesis and help to design better strategies for APLs in further studies. Disclosures No relevant conflicts of interest to declare.

Description: Abstract 3544 Poster Board III-481 Objective To explore the impact and mechanism of keratinocyte growth factor (KGF) infusion on immune reconstitution post murine allogeneic umbilical cord blood cell transplantation (UCBT). Methods Mix cord blood was obtained at E19.5 from several litters of B6 females and was used as umbilical cord blood (UCB) graft. Thirty-two BALB/c mice were randomly assigned to 4 groups with 8 mice per group in the first cohort UCBT, mice were reconstituted with PBS or 1×106, 2×106, 3×106 UCB mononuclear cells (MNCs). Twenty-four BALB/c mice were randomly assigned to 3 groups with 8 mice per group in the second cohort UCBT, mice were injected with 1×106, 2×106 or 3×106 MNCs. All mice received platelet transfusion on +8d. Sixteen BALB/c mice were randomly assigned to 2 groups with 8 mice per group in the third cohort UCBT, mice were injected s.c. with KGF or PBS before TBI. All mice were injected with 2×106 MNCs and were supported with platelet transfusion on +8d. We studied survival, splenic lymphoid cell subsets, sjTREC assay after UCBT. Results The survival rates at +100d of mice resconstituted with allogeneic 1×106, 2×106, 3×106 UCB MNCs were 25%, 37.5% and 37.5% in the first cohort UCBT,respectively. The survival rates at +100d of mice injected with 1×106, 2×106, 3×106 MNCs and with platelet support were 87.5%, 100.0% and 100.0%, respectively. The splenic T, NKT, NK and B cell counts in PBS treated control mice on +35d were (9.57±0.74)×106, (0.64±0.06)×106, (1.43±0.10)×106 and (19.13±1.50)×106, respectively. While in KGF treated mice on +35d were (13.47±0.74)×106, (0.89±0.03)×106, (1.79±0.04)×106 and (20.50±0.91)×106, respectively. The level of sjTREC in control mice was 182.2±10.7copies per 105 cells Gwhile that of KGF treated mice was 224.2±9.6 copied per 105 cells and was higher than that of control mice (P=0.019). Conclusion Peripheral blood abtained from E19.5d fetus is rich in hematopoietic stem cells. We established a murine allogeneic UCBT model with platelet support on +8d. KGF treatment could enhance immune reconstitution after UCBT. Disclosures: No relevant conflicts of interest to declare.