scholarly journals Measuring H3K27me3 Reduction after in-Vivo Administration of Ftx-6058; A Potent Polycomb Repressive Complex 2 (PRC2) Inhibitor

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 4164-4164
Author(s):  
Mark Roth ◽  
Keqiang Xie
Keyword(s):  
Bone Marrow ◽  
Histone H3 ◽  
Hematopoietic Cells ◽  
Tissue Type ◽  
Target Cells ◽  
Flow Cytometric Assay ◽  
Publicly Traded ◽  
Total Histone ◽  
Flow Cytometric

Abstract FTX-6058 is an investigational drug for the treatment of Sickle Cell Disease (SCD). The molecule is a selective and potent binder of the embryonic ectoderm development protein (EED). Binding of FTX-6058 to EED inhibits PRC2, a histone methyltransferase which primarily methylates lysine 27 of histone H3. Inhibition of PRC2 results in the reduction of trimethylation at lysine 27 on histone H3 (H3K27me3). Because the level of trimethylation on lysine 27 is the immediate downstream consequence of PRC2 activity, we developed a flow cytometric assay to measure the relative level of H3K27me3 from in-vivo tissue samples. The flow cytometric assay measures the median fluorescence intensities (MFI) of H3K27me3 and total histone H3. The target engagement (TE) measurement is a ratio of H3K27me3 MFI to total Histone H3 MFI. The target cells for FTX-6058 in SCD treatment are the hematopoietic cells of the bone marrow. We demonstrate an FTX-6058 dose dependent decrease in the TE ratio of bone marrow, hematopoietic cells. Translating the TE assay from mouse pre-clinical studies to human clinical trials required use of a less invasive tissue type than bone marrow. In mice, a positive relationship between the TE ratio of hematopoietic, bone marrow cells and circulating monocytes was established. Therefore, a human monocyte TE assay for FTX-6058 was validated for human trials. Research use only (RUO) validation was completed by Q2 Solutions Laboratories. The monocyte FTX-6058 TE assay is currently being evaluated as an exploratory biomarker in Fulcrum Therapeutics' phase 1 clinical trial FIS 002-2020. Disclosures Roth: Fulcrum Therapeutics, Inc.: Current Employment, Current equity holder in publicly-traded company. Xie: Fulcrum Therapeutics, Inc.: Current equity holder in publicly-traded company, Ended employment in the past 24 months.

Improved Analysis of Hematopoietic Engraftment by Non-Invasive In Vivo Bioluminescent Imaging of Transplanted Human Embryonic Stem Cell-Derived Hematopoietic Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1270-1270
Author(s):  
Jonathan L. Linehan ◽  
Xinghui Tian ◽  
Julie K. Morris ◽  
Dan S. Kaufman
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Es Cells ◽  
Hematopoietic Cells ◽  
Embryonic Stem ◽  
Scid Mice ◽  
Cell Lineages ◽  
Non Invasive ◽  
Flow Cytometric

Abstract Animal transplantation models are essential to characterize the long-term in vivo engraftment capacity of putative hematopoietic stem cells derived from human embryonic stem cells (hESCs). We have previously demonstrated that hESCs can be routinely utilized to derive multiple hematopoietic cell lineages. Here, we use in vivo bioluminescence imaging (BLI) of stable luciferase (luc)-expressing hESCs to noninvasively monitor the dynamics of transplantation, engraftment, and growth of hESC-derived hematopoietic cells within individual animals over an extended time course. Luc expression under control of an EF1α promoter was introduced into the H1 hESC line using a self-inactivating lentiviral vector. Undifferentiated hESC colonies that stably expressed luciferase were established and selected, and the pluripotent capability of luc+ hESCs was first explored by teratoma formation. Undifferentiated luc+ human ES cells were intramuscularly injected into NOD/SCID mice. The dynamics of survival and growth of the hESCs was monitored by BLI using the IVIS Imaging System (Xenogen) at regular time points post-transplantation. There was a decrease of luminescent signal during the first 1–2 weeks. This was followed by a dramatic increase in luminescent signals after about 5 weeks, which correlated with teratoma size. Immunohistochemical analysis confirmed stable luc-expression in multiple differentiated cell types within the teratomas. We next used BLI to examine luc+ H1 hESCs that were induced to undergo hematopoietic differentiation by co-culture with S17 cells, to give rise to H1/S17 cells. Flow cytometric studies confirmed hematopoietic cells (CD34+, CD45+, CD31+, and c-kit+ cells) were derived from these differentiated luc+ hESCs, with 5–10% of H1/S17 cells being CD34+. Hematopoietic progenitors that gave rise to colonies of mature luc+ blood cells in a standard CFU assay were also observed from the H1/S17 cells. Luc-expression of differentiated hESCs was maintained at similar levels to those of the undifferentiated ES cells. To define the in vivo potential of luc+ hESC-derived hematopoietic cells, hESCs were allowed to differentiate on S17 cells for two weeks. SCID-repopulating cell studies were done by intravenous (iv) injection into sublethally irradiated NOD/SCID mice. After iv injection of 2–3 x106 unsorted luc+ H1/S17 cells, BLI showed the brightest signal in the lung at day 0 (within 2 hours), followed by a rapid decline in signal on the next day (day1). On day 8, most luc+ cells were detected in the abdomen and liver. Subsequently, after 6–12 weeks, multiple engraftment loci were identified in hematopoietic tissues. Flow cytometric analysis of bone marrow from these mice confirmed the presence of hESC-derived human CD45+ cells. Engraftment was also demonstrated after direct intra-bone marrow injection with as few as 60,000 CD34+ cells sorted from luc+ H1/S17 cells. Again, stable engraftment can be monitored by BLI for 8+ weeks. These results demonstrate that BLI has several important advantages as an effective non-invasive approach to track and quantitatively monitor in vivo engraftment of hematopoietic or other cell lineages derived from hESCs.

scholarly journals Primitive Human Hematopoietic Cells Are Enriched in Cord Blood Compared With Adult Bone Marrow or Mobilized Peripheral Blood as Measured by the Quantitative In Vivo SCID-Repopulating Cell Assay

Blood ◽  
1997 ◽  
Vol 89 (11) ◽  
pp. 3919-3924 ◽  
Author(s):  
Jean C.Y. Wang ◽  
Monica Doedens ◽  
John E. Dick
Keyword(s):  
Bone Marrow ◽  
Cord Blood ◽  
Peripheral Blood ◽  
Hematopoietic Cells ◽  
Allogeneic Transplantation ◽  
Functional Assay ◽  
Hematopoietic Stem ◽  
Mobilized Peripheral Blood

Abstract We have previously reported the development of in vivo functional assays for primitive human hematopoietic cells based on their ability to repopulate the bone marrow (BM) of severe combined immunodeficient (SCID) and nonobese diabetic/SCID (NOD/SCID) mice following intravenous transplantation. Accumulated data from gene marking and cell purification experiments indicate that the engrafting cells (defined as SCID-repopulating cells or SRC) are biologically distinct from and more primitive than most cells that can be assayed in vitro. Here we demonstrate through limiting dilution analysis that the NOD/SCID xenotransplant model provides a quantitative assay for SRC. Using this assay, the frequency of SRC in cord blood (CB) was found to be 1 in 9.3 × 105 cells. This was significantly higher than the frequency of 1 SRC in 3.0 × 106 adult BM cells or 1 in 6.0 × 106 mobilized peripheral blood (PB) cells from normal donors. Mice transplanted with limiting numbers of SRC were engrafted with both lymphoid and multilineage myeloid human cells. This functional assay is currently the only available method for quantitative analysis of human hematopoietic cells with repopulating capacity. Both CB and mobilized PB are increasingly being used as alternative sources of hematopoietic stem cells in allogeneic transplantation. Thus, the findings reported here will have important clinical as well as biologic implications.

scholarly journals Nuclear oncoprotein expression as a function of lineage, differentiation stage, and proliferative status of normal human hematopoietic cells

Blood ◽  
1989 ◽  
Vol 74 (5) ◽  
pp. 1517-1524 ◽  
Author(s):  
MB Kastan ◽  
KD Stone ◽  
CI Civin
Keyword(s):  
Progenitor Cells ◽  
Control Cell ◽  
Hematopoietic Cells ◽  
Maturation Stage ◽  
Flow Cytometric Assay ◽  
Lineage Differentiation ◽  
Flow Cytometric ◽  
A Cell ◽  
Normal Human ◽  
Differentiation Stage

Abstract Relative levels of the nuclear oncoproteins c-myb, c-myc, and c-fos were determined in selected subpopulations of normal human bone marrow (BM) cells using a flow cytometric assay which simultaneously detects a cell-surface antigen (as a marker of lineage and stage of maturation) and levels of an intracellular protein. At least two monoclonal antibodies directed against each oncoprotein and specific peptide inhibition controls were used for these determinations. Hematopoietic progenitor cells (CD34+) express the highest levels of c-myb and c-myc, whereas c-fos levels in CD34+ progenitor cells are similar to c-fos levels in mature monocytes and granulocytes. Granulocytes are the only hematopoietic cells examined which do not express detectable levels of c-myb and c-myc. The levels of these oncoproteins in these normal, unstimulated BM cell populations were more closely linked to lineage and maturation stage than to the proliferative status of the given population, as determined by either DNA staining or expression of the cell-cycle specific nuclear protein, Ki67. This flow cytometric assay helps in interpreting the significance of oncoprotein levels in leukemia cells by allowing direct comparisons of a leukemia with the phenotypically similar “normal counterpart control” cell population in normal BM.

Preclinical Evaluation of a Bone-Marrow Autograft Culture Procedure for Generating Lymphokine-Activated Killer Cells in Vitro

1992 ◽  
Vol 3 (suppl b) ◽  
pp. 123-127 ◽  
Author(s):  
Hans-Georg Klingemann ◽  
Heather Deal ◽  
Dianne Reid ◽  
Connie J Eaves
Keyword(s):  
Bone Marrow ◽  
Calf Serum ◽  
Cell Activity ◽  
Hematopoietic Cells ◽  
Lak Cells ◽  
High Dose ◽  
Lymphokine Activated Killer Cells ◽  
Lak Cell

Despite the use of high dose chemoradiotherapy for the treatment of acute leukemia. relapse continues to be a major cause of death in patients given an autologous bone marrow transplant. Further augmentation of pretransplant chemotherapy causes life threatening toxicity to nonhematopoietic tissues and the effectiveness of currently available ex vivo purging methods in reducing the relapse rate is unclear. Recently, data from experimental models have suggested that bone marrow-derived lymphokine (IL-2)-activated killer (BM-LAK) cells might be used to eliminate residual leukemic cells both in vivo and in vitro. To evaluate this possibility clinically, a procedure was developed for culturing whole marrow harvests with IL-2 prior to use as autografts, and a number of variables examined that might affect either the generation of BM-LAK cells or the recovery of the primitive hematopoietic cells. The use of Dexter long term culture (LTC) conditions, which expose the cells to horse serum and hydrocortisone. supported LAK cell generation as effectively as fetal calf serum (FCS) -containing medium in seven-day cultures. Maintenance of BM-LAK cell activity after a further seven days of culture in the presence of IL-2 was also tested. As in the clinical setting. patients would receive IL-2 in vivo for an additional week immediately following infusion of the cultured marrow autograft. Generation ofBM-LAK activity was dependent on the presence of IL-2 and could be sustained by further incubation in medium containing IL-2. Primitive hematopoietic cells were quantitated by measuring the number of in vitro colony-forming progenitors produced after five weeks in secondary Dexter-type LTC. Maintenance of these 'LTC-initiating cells' was unaffected by lL-2 in the culture medium. These results suggest that LAK cells can be generated efficien tly in seven-day marrow autograft cultures containing IL-2 under conditions that allow the most primitive human hematopoietic cells currently detectable to be maintained.

Gene transfer into normal human hematopoietic cells using in vitro and in vivo assays

Blood ◽  
1991 ◽  
Vol 78 (3) ◽  
pp. 624-634 ◽  
Author(s):  
JE Dick ◽  
S Kamel-Reid ◽  
B Murdoch ◽  
M Doedens
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Gene Transfer ◽  
Hematopoietic Cells ◽  
Human Stem Cells ◽  
In Vivo Assays ◽  
Genetically Manipulated ◽  
Deficient Mice

Abstract The ability to transfer new genetic material into human hematopoietic cells provides the foundation for characterizing the organization and developmental program of human hematopoietic stem cells. It also provides a valuable model in which to test gene transfer and long-term expression in human hematopoietic cells as a prelude to human gene therapy. At the present time such studies are limited by the absence of in vivo assays for human stem cells, although recent descriptions of the engraftment of human hematopoietic cells in immune-deficient mice may provide the basis for such an assay. This study focuses on the establishment of conditions required for high efficiency retrovirus- mediated gene transfer into human hematopoietic progenitors that can be assayed in vitro in short-term colony assays and in vivo in immune- deficient mice. Here we report that a 24-hour preincubation of human bone marrow in 5637-conditioned medium, before infection, increases gene transfer efficiency into in vitro colony-forming cells by sixfold; interleukin-6 (IL-6) and leukemia inhibitory factor (LIF) provide the same magnitude increase as 5637-conditioned medium. In contrast, incubation in recombinant growth factors IL-1, IL-3, and granulocyte- macrophage colony-stimulating factor increases gene transfer efficiency by 1.5- to 3-fold. Furthermore, preselection in high concentrations of G418 results in a population of cells significantly enriched for G418- resistant progenitors (up to 100%). These results, obtained using detailed survival curves based on colony formation in G418, have been substantiated by directly detecting the neo gene in individual colonies using the polymerase chain reaction. Using these optimized protocols, human bone marrow cells were genetically manipulated with a neo retrovirus vector and transplanted into immune-deficient bg/nu/xid mice. At 1 month and 4 months after the transplant, the hematopoietic tissues of these animals remained engrafted with genetically manipulated human cells. More importantly, G418-resistant progenitors that contained the neo gene were recovered from the bone marrow and spleen of engrafted animals after 4 months. These experiments establish the feasibility of characterizing human stem cells using the unique retrovirus integration site as a clonal marker, similar to techniques developed to elucidate the murine stem cell hierarchy.

Enforced Expression of the GATA-2 Transcription Factor Blocks Normal Hematopoiesis

Blood ◽  
1999 ◽  
Vol 93 (2) ◽  
pp. 488-499 ◽  
Author(s):  
Derek A. Persons ◽  
James A. Allay ◽  
Esther R. Allay ◽  
Richard A. Ashmun ◽  
Donald Orlic ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Transcription Factor ◽  
Blood Cell ◽  
Fluorescent Protein ◽  
Bone Marrow Cells ◽  
Hematopoietic Cells ◽  
Immunoblot Analysis ◽  
Marrow Cells

Abstract The zinc finger transcription factor GATA-2 is highly expressed in immature hematopoietic cells and declines with blood cell maturation. To investigate its role in normal adult hematopoiesis, a bicistronic retroviral vector encoding GATA-2 and the green fluorescent protein (GFP) was used to maintain the high levels of GATA-2 that are normally present in primitive hematopoietic cells. Coexpression of the GFP marker facilitated identification and quantitation of vector-expressing cells. Bone marrow cells transduced with the GATA-2 vector expressed GFP as judged by flow cytometry and GATA-2 as assessed by immunoblot analysis. A 50% to 80% reduction in hematopoietic progenitor-derived colony formation was observed with GATA-2/GFP-transduced marrow, compared with marrow transduced with a GFP-containing vector lacking the GATA-2 cDNA. Culture of purified populations of GATA-2/GFP-expressing and nonexpressing cells confirmed a specific ablation of the colony-forming ability of GATA-2/GFP-expressing progenitor cells. Similarly, loss of spleen colony-forming ability was observed for GATA-2/GFP-expressing bone marrow cells. Despite enforced GATA-2 expression, marrow cells remained viable and were negative in assays to evaluate apoptosis. Although efficient transduction of primitive Sca-1+Lin- cells was observed with the GATA-2/GFP vector, GATA-2/GFP-expressing stem cells failed to substantially contribute to the multilineage hematopoietic reconstitution of transplanted mice. Additionally, mice transplanted with purified, GATA-2/GFP-expressing cells showed post-transplant cytopenias and decreased numbers of total and gene-modified bone marrow Sca-1+ Lin−cells. Although Sca-1+ Lin− bone marrow cells expressing the GATA-2/GFP vector were detected after transplantation, no appreciable expansion in their numbers occurred. In contrast, control GFP-expressing Sca-1+Lin− cells expanded at least 40-fold after transplantation. Thus, enforced expression of GATA-2 in pluripotent hematopoietic cells blocked both their amplification and differentiation. There appears to be a critical dose-dependent effect of GATA-2 on blood cell differentiation in that downregulation of GATA-2 expression is necessary for stem cells to contribute to hematopoiesis in vivo.

Optical Imaging of PKH‐Labeled Hematopoietic Cells in Recipient Bone Marrow In Vivo

Stem Cells ◽  
2002 ◽  
Vol 20 (6) ◽  
pp. 501-513 ◽  
Author(s):  
Nadir Askenasy ◽  
Daniel L. Farkas
Keyword(s):  
Bone Marrow ◽  
Optical Imaging ◽  
Hematopoietic Cells

scholarly journals Proliferative Tumor Doubling Times of Prostatic Carcinoma

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Priya N. Werahera ◽  
L. Michael Glode ◽  
Francisco G. La Rosa ◽  
M. Scott Lucia ◽  
E. David Crawford ◽  
...  
Keyword(s):  
Normal Tissue ◽  
Prostatic Carcinoma ◽  
Flow Cytometric Analysis ◽  
Flow Cytometric Assay ◽  
Flow Cytometric ◽  
Biological Potential ◽  
Aggressive Tumors ◽  
Doubling Times ◽  
Biological Differences

Prostate cancer (PCa) has a variable biology ranging from latent cancer to extremely aggressive tumors. Proliferative activities of cancers may indicate their biological potential. A flow cytometric assay to calculate maximum proliferative doubling times (Tmax) of PCa in radical prostatectomy specimens after preoperativein vivobromodeoxyuridine (BrdU) infusion is presented. Only 4/17 specimens had tumors large enough for flow cytometric analysis. TheTmaxof tumors was similar and ranged from 0.6 to 3.6 months. Tumors had calculated doubling times 2- to 25-fold faster than their matched normal tissue. Variations in labeling index andTmaxwere observed within a tumor as well as between different Gleason grades. The observed PSA doubling times (PSA-DT) ranged from 18.4 to 32.0 months, considerably slower than the correspondingTmaxof tumors involved. While lack of data for apoptotic rates is a limitation, apparent biological differences between latent versus aggressive PCa may be attributable to variations in apoptotic rates of these tumors rather than their cell proliferative rates.

Exhaustion of Donor Hematopoietic Stem Cells in Lethally-Irradiated Hosts Can Be Sbstantially Mitigated by Targeting p18INK4C.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1200-1200
Author(s):  
Hui Yu ◽  
Youzhong Yuan ◽  
Xianmin Song ◽  
Feng Xu ◽  
Hongmei Shen ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Kinase Inhibitor ◽  
Hematopoietic Cells ◽  
Hematopoietic Stem ◽  
Total Period ◽  
Over Expression

Abstract Hematopoietic stem cells (HSCs) are significantly restricted in their ability to regenerate themselves in the irradiated hosts and this exhausting effect appears to be accelerated in the absence of the cyclin-dependent kinase inhibitor (CKI), p21. Our recent study demonstrated that unlike p21 absence, deletion of the distinct CKI, p18 results in a strikingly positive effect on long-term engraftment owing to increased self-renewing divisions in vivo (Yuan et al, 2004). To test the extent to which enhanced self-renewal in the absence of p18 can persist over a prolonged period of time, we first performed the classical serial bone marrow transfer (sBMT). The activities of hematopoietic cells from p18−/− cell transplanted mice were significantly higher than those from p18+/+ cell transplanted mice during the serial transplantation. To our expectation, there was no detectable donor p18+/+ HSC progeny in the majority (4/6) of recipients after three rounds of sBMT. However, we observed significant engraftment levels (66.7% on average) of p18-null progeny in all recipients (7/7) within a total period of 22 months. In addition, in follow-up with our previous study involving the use of competitive bone marrow transplantation (cBMT), we found that p18−/− HSCs during the 3rd cycle of cBMT in an extended long-term period of 30 months were still comparable to the freshly isolated p18+/+ cells from 8 week-old young mice. Based on these two independent assays and the widely-held assumption of 1-10/105 HSC frequency in normal unmanipulated marrow, we estimated that p18−/− HSCs had more than 50–500 times more regenerative potential than p18+/+ HSCs, at the cellular age that is equal to a mouse life span. Interestingly, p18 absence was able to significantly loosen the accelerated exhaustion of hematopoietic repopulation caused by p21 deficiency as examined in the p18/p21 double mutant cells with the cBMT model. This data directly indicates the opposite effect of these two molecules on HSC durability. To define whether p18 absence may override the regulatory mechanisms that maintain the HSC pool size within the normal range, we performed the transplantation with 80 highly purified HSCs (CD34-KLS) and then determined how many competitive reconstitution units (CRUs) were regenerated in the primary recipients by conducting secondary transplantation with limiting dilution analysis. While 14 times more CRUs were regenerated in the primary recipients transplanted with p18−/−HSCs than those transplanted with p18+/+ HSCs, the level was not beyond that found in normal non-transplanted mice. Therefore, the expansion of HSCs in the absence of p18 is still subject to some inhibitory regulation, perhaps exerted by the HSC niches in vivo. Such a result was similar to the effect of over-expression of the transcription factor, HoxB4 in hematopoietic cells. However, to our surprise, the p18 mRNA level was not significantly altered by over-expression of HoxB4 in Lin-Sca-1+ cells as assessed by real time PCR (n=4), thereby suggesting a HoxB4-independent transcriptional regulation on p18 in HSCs. Taken together, our current results shed light on strategies aimed at sustaining the durability of therapeutically transplanted HSCs for a lifetime treatment. It also offers a rationale for the feasibility study intended to temporarily target p18 during the early engraftment for therapeutic purposes.

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