American Society of Hematology (ASH) annual meeting has been started Yesterday in San Diego. This meeting is the great opportunity to learn about the progress in hematopoietic stem cell biology and transplantation. I’m not attending the meeting, but I’ve read many abstracts available online. I’ve picked some abstracts for our “True Blood” series, which will be presented at conference.
Platelet production from human iPS cells
Koji Eto’s group from CiRA (Japan) continue to develop the best step by step protocol for generation of platelet from human iPS cells. Last year they demonstrated the significance of c-MYC in generation of human platelet from iPS cells. This year, they are presenting data about generation and genetic modifications of immortalized megakaryocyte cell line (MKCL) for platelet production:
As mentioned, a decline in c-MYC activation during hiPSC-derived megakaryocyte maturation is required for generation of functional CD41a+/CD42b+ platelets in vitro.
By using an inducible expression vector system with c-MYC and BMI1 in this context, the MKCL was capable of generating polyploid megakaryocytes (>8N; 40%). The MKCL also subsequently showed proplatelet formation leading to the release of “functional” CD41a+/CD42b+ platelets. Furthermore, following transfusion of 6×108 platelets originally derived from the our immortalized MKCL into immunodeficient NOG mice, the platelets appeared to exhibit normal circulation a high degree of chimerism.
We therefore propose that establishment of immortalized MKPCs through gene manipulation could potentially provide a stable supply of platelets at a predefined quality and quantity for transfusion therapy.
Natural Killer (NK) cells from human iPS – clinical-grade tune up
Dan Kaufman’s group from U of Minnesota continue to develop a protocol for clinical-grade generation of NK cells from human pluripotent (ES and iPS) cells. They are presenting a data about functionality of iPS cell-derived NK cells against multiple myeloma (MM) and improvement of cell culture:
Here, we demonstrate hESC- and iPSC-derived NK cell development in a completely defined, feeder-free system that is amenable to clinical scale-up.
We have now tested the activity of hESC- and iPSC-derived NK cells against MM tumor cells in order to provide a universal source of lymphocytes for adoptive immunotherapy in patients with treatment refractory disease. We find that similar to peripheral blood NK cells (PB-NK), hESC- and iPSC-derived NK cells are cytotoxic against 3 distinct MM cell lines in a standard chromium release cytotoxicity assay. We find that similar to peripheral blood NK cells (PB-NK), hESC- and iPSC-derived NK cells are cytotoxic against 3 distinct MM cell lines in a standard chromium release cytotoxicity assay. Specifically, activated PB-NK cells killed 48.5% of targets at 10 to 1 effector to target ratios, whereas hESC (46.3%) and iPSC (42.4%) derived NK cells also demonstrated significant anti-MM activity.
Comparative blood group profiling of human Erythroid Cells (EBs) generated from Adult Blood (AB), Cord Blood (CB), Human Embryonic Stem Cells (hESC) and Induced Pluripotent Stem Cells (iPS)
I love comparative studies! They are rare and, usually, provide very important results. Barbara Ghinassi et al. compared potential immunogenicity and quality (via assessment of blood groups antigens) of red blood cells generated from different stem cell sources:
The observation that blood group antigenic profiles of ex-vivo generated EBs are consistent with those predicted by DNA-genotyping suggests that these cells are unlikely to be immunogenic for known epitopes. However, the antigen profiles of ankyrin R and 4.1R complexes were normal only for AB and iPS-derived EBs raising the possibility that antigenic deviations seen in EBs derived from CB and hESC may have immunologic or functional consequences in vivo.
Generation of T-cells from human iPS
For the purpose, generation of induced pluripotent stem (iPS) cells from an antigen-reactive single T lymphocyte is attractive and rewarding way. iPS cells have a capacity for unlimited self-renewal while maintaining pluripotency. These features may enable us to induce an unlimited number of T lymphocytes, especially high proliferative naïve / central memory-type T lymphocytes, showing reactivity to specific antigens. If they retain properties of naïve T lymphocytes, they may proliferate for a longer period and achieve better therapeutic effects than their peripheral blood counterparts expanded in vitro.
Making a clinical-grade “off-the-shelf” cell product for treatment of thrombocytopenia
Expanded megakaryocyte progenitors, generated from mobilized CD34+ cells, developed by Cellerant Therapeutics:
We have developed a novel approach to reconstitute megakaryocytes and platelets in thrombocytopenic patients which is presented here. We have identified a scalable culture system using serum-free medium and a defined cytokine cocktail free of animal products to expand CD34+ hematopoietic stem cells from G-CSF mobilized peripheral blood donors in vitro and direct their development to the megakaryocyte lineage to yield committed human megakaryocyte progenitors (MKPs).
2 abstracts about direct transdifferentiation by defined factors
iNCs: Cord blood-derived neurons by ectopic expression of SOX2 and c-MYC
iMK: Induction of megakaryocytes from fibroblasts by p45NF-E2/Maf
You can follow updates from conference by a hashtag #ASH11
If you’re attending the meeting right now, please tell us about your impressions!