Peripheral Blood Stem Cell (PBSC) Collections: Why, What, When. Objectives. Sources of Stem Cells

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1 Peripheral Blood Stem Cell (PBSC) Collections: Why, What, When Objectives Why do need stem cell transplants What type of cells are we using for stem cell transplants When and how we collect peripheral blood stem cells Bone Marrow Transplantation Can Cure: Leukemia Lymphoma Multiple Myeloma Solid Tumors: Brain tumors Non-malignant hematological Diseases/genetic diseases: Sickle Cell Disease, Thalassemia, Fanconi s Anemia, Immunodeficiency Syndromes Bone Marrow Sources of Stem Cells Peripheral Blood Stem Cells (PBSC) Cord Blood June 2000 Advantage Disadvantage Sources of Hematopoietic Stem Cells Bone Marrow June 2000 Bone Marrow Large number of cells Lower number of mature T-cells Surgical procedure General anesthesia Peripheral Blood Stem Cells (PBSC) Peripheral Blood Easy to collect Multiple collection Cord Blood Treatment with G-CSF Bone pain May require central venous access Cord Blood Collection has no risks Readily available Low cell dose No multiple collection Multiple Randomized Trials of Mobilized PBSC in Autologous Transplantation Shorter duration of cytopenias Enhanced immune reconstitution Reduced morbidity PBSC primary source of stem cells for autologous transplantation 1

2 Initial pilot trials of Mobilized PBSC in allogeneic transplantation Improve neutrophil and platelet engraftment Reduction of infectious complications Better early survival in patients with advanced disease No apparent increase risk of acute GVHD Increase in risk of chronic GVHD Hematopoiesis Hierarchy Stem Cells Progenitor Cells Precursors Self- Renewal CD 34+ Amplification and Differentiation Dull Rhodamine Bright Cells in Cycle Lineage Morphologically Specific Identifiable Markers The PBSC Dose HPCs Quantification All surrogate markers Clonogenic assays (functional assays): Culture in methyl cellulose (CFU) Long-term culture-initiating-cells (LT-CIC) CD34 surface antigen *Transmambrane glycoprotein; present on immature hematopoietic cells (also mature endothelial cells, stromal cells) *Flow Cytometry: Assay of choice *Can quantify within few hours *Detect low frequency of cells The PBSC Dose HPCs Quantification: Why CD34 CD34 remains the major surface marker for identifying early progenitors Craig Jordan University of Rochester 2

3 The PBSC Dose HPCs Quantification Why CD34 (cont.) The number of CD34+ cells in peripheral blood stem cell collection correlates to the Colony Forming Units for granulocytes/macrophages (CFU- GM) which measure the ability to give rise to colonies of different lineages. The PBSC Dose Required for Transplant CD34 dose required for rapid engraftment in recipients ranges from 1-5 X10 6 /kg of recipient weight. Minimum dose required (the more the better..- plt engraft.; febrile comp.): Autologous : 1-2 X10 6 /kg Allogeneic : 2-5 X10 6 /kg If manipulations are needed e.g. T-cell removal (prevent/ GVHD) some HPCs will also be lost, even greater quantities must be collected. Jansen et al 2005 So, we know who we need How do we collect the dose we need? In Steady State HPCs circulating in very low concentration: CD34 is present on ~1.5% (1-3%) of the BM Cells & <0.1% of WBC in PB. CD34 concentration in PB is 2-5X10 6 /L For transplant recipient 70kg - you will need 2-5X10 6 /kg = X10 6 CD X10 6 CD34: you need to collect 2-5X10 6 /L L blood Apheresis machines collect 50-70% CD34 cells from the blood L blood would have to be processed Impractical, expensive and probably not possible something has to be done Increase the Yield of Collection Increase number of CD34 cells - mobilization Increase volume of blood processed each collection Increase number of collections 3

4 Mobilization of PBSCs Hematopoietic Growth Factors: FDA approved: Granulocyte colony stimulating factor (G-CSF), Granulocyte/macrophage stimulating factor (GM-CSF) Chemotherapy (not for allogeneic donors) HPCs (X20-25) during early hem. Recovery phase after chemotherapy-induced-marrow-aplasia AMD3100 (experimental) Potent and selective inhibitor of CXCR4 Reversible inhibition of the binding of stromaderived factor (SDF-1) to its receptor CXCR4 Mobilization of PBSCs Mechanism of Action More stem cells Induction of endogenous production/ release of hematopoietic cytokines in response to HGF/chemo actions on dividing cells More into the circulation Signals induced after chemo or HGF, counteracted normal mechanisms such as adhesion to stroma and extracellular matrix responsible for retaining stem cells the in marrow Inhibition of osteoblast function Stem cells escape because of overcrowding in the marrow during recovery from chemo or HGF Mobilization of PBSCs Hematopoietic Growth Factors: FDA approved: Granulocyte colony stimulating factor (G-CSF), Granulocyte/macrophage stimulating factor (GM-CSF) Chemotherapy (not for allogeneic donors) HPCs (X20-25) during early hem. Recovery phase after chemotherapy-induced-marrow-aplasia AMD3100 (experimental) Potent and selective inhibitor of CXCR4 Reversible inhibition of the binding of stromaderived factor (SDF-1) to its receptor CXCR4 Hematopoietic Growth Factors S.O.C for mobilization of allogeneic donors G-CSF mobilizes dose of CD34+ cells; shorter engraftment time GM-CSF has rates of side effects; severity Both agents may mobilize different populations of HPCs combination is possible Combination with chemo 4

5 Hematopoietic Growth Factors Dose S.C. Single daily dose or divided twice daily (probably more effective mobilization; less convenient) Peak levels 2-8 hours; t 1/2 :3.5 hours Mobilization 2-5 g/kg/day Typically 5-10 g/kg/day (can go up to 20) Hematopoietic Growth Factors WBC Effects (Healthy Donors) WBC, gran. within 12-18H post first dose Usually WBC to x10 9 /L Gran. will stay as long as daily dose is continued Lymphocyte, monocyte count slightly Hematopoietic Growth Factors CD34 Effects (Healthy Donors) Do not until 3-4 daily doses are given Maximum after 4-5 doses After that- even if continue G-CSF Window of collection is very narrow Most centers will start collections 12-24h post 3-5 days of G-CSF injection Hematopoietic Growth Factors CD34 Effects Cont. Therapeutic dose for 5 days: CD fold (w/chemo ) Peak CD34 cell count on D4-5: /L Wide interindividual variability Hematopoietic Growth Factors CD34 Effects - Cont. Preharvest CD34 cell concentration in the donor s blood is predictive of the total yield of progenitor cells In general, a peripheral blood CD34 cell concentration of 10 /L can be expected to result in a yield of at least 1X10 6 /kg Other factors: gender (M>F), weight (H>L), age (<65 better yield), prior chemo/radiation So, When to start the collection? At least 4-5 days of G-CSF injection WBC: x10 9 /L; 5-10 after chemo, Peds lower Preharvest peripheral blood CD34 cell concentration of at least 10 /L (allo higher; auto- lower the important thing is to set a threshold!!!) 5

6 HPC Collections Technical Aspects 1 Most instruments continuously draw ml/minute of donor s blood Duration is determined by the volume of blood that is processed (10-20L 3-5 hours: long procedures) Example: 10,000ml/50ml/min=200min >3 hours Return the remaining blood cells and plasma to the donor Venous access required: large-bore needles at two separate sites or double-lumen indwelling catheter HPC Collections Technical Aspects 2 Extracorporeal Volume (ECV): the amount of blood outside the patient s body at any given time Should not exceed 15% of patient's total estimated blood volume Depend on the technology (machine, procedure) used, it varies between ml HPC Collections Technical Aspects 2 (cont.) Usually saline is used for priming of the extracorporeal circuit When the patient is connected, anticoagulated whole blood is withdrawn from the patient and the saline prime is diverted to the waste collection bag No replacement fluid is administred until saline diversion is complte Resulting in initial deficit fluid balance which is mainitained during the procedure Corrected only at the end of the procedure by returning an equal or greater volume of replacement fluid during rinseback of the centrifuge chamber contents HPC Collections Technical Aspects 2 (cont.) Adult/older children are able to withstand the fluid shifts and the mild hemodilution associated with standard saline prime Smaller children (<20-25Kg) are not able to do so Thus, prime of the circuit is done with RBCs Preventing large shifts in fluid balance and maintain an adequate Hematocrit during the procedure Pediatrics (<20kg) RBC prime HPC Collections Technical Aspects 2 (cont.) Performing blood prime: Extracorporeal circuit is initially primed with saline The saline is diverted to the waste collection bag as the circuit is filled with donor RBCs Upon patient collection, whole blood is drawn form the patient and donor blood is returned. Euvolumia is maintained throughout the procedure, no rinseback is done Centrifugal Separation Plasma Plasma Platelets Platelets Buffy Buffy Coat Coat Red Red Cells Cells 6

7 HPC Collections Technical Aspects 3 Apheresis: Principles of Separation Blood cell separators primarily use cell size and density to separate cell types HPCs are similar in size and density to lymphocytes and monocytes HPCs are collected with large number of lymphocytes and platelets Platelets (1040) Lymphocytes ( ) Monocytes ( ) Granulocyte ( ) RBC Platelets (1040) Lymphocytes ( ) Monocytes ( ) Granulocyte ( ) RBC Cobe PBSC Collection Guide G WB WBC PRBC Plasma What s in the HPC Bag 90-95% of WBC are MNC (lymph, mono) <10% of WBC are granulocytes Only 1-2% of MNC express CD34 Very few ml of RBCs : ~1ml/L processed Relatively large amount of PLTs Plasma volume collected varies: ml depend on the machine/program used (collect autologous plasma if needed ) Increase the Yield of Collection Increase number of CD34 cells - mobilization Increase number of collections Increase volume of blood processed each collection 7

8 Collecting Enough HPCs No. of Collections Adequate quantity for allo transplant: 1 collection 62-68% 2 collections 86-91% Yield of 2 nd collection is ~20% less than the first (if high dose G-CSF given) This yield reduction results from in CD34 conc. in the blood prior to collection Yield of 3 rd collection is even lower; fourth is not worthwhile Collecting Enough HPCs No. of Collections 0.3-4% of donors, not enough cells w>2 collections low-yield-first-collection 2 nd collection attempted >1 y of 1 st collect. <60d of 1 st collection CD 34 mobilization & CD 34 mobilization & yield > to 1 st collection yield < 1 st collection Collecting Enough HPCs Volume The best option to increase yield - volume of each of the first 2 collections. LVL: 4-5 TBV (most common 20L) There is an equilibrium of non-circulating HPCs into peripheral circulation with large volume collections Recruitment of CD34+ cells and MNC to the PB (no gran., plt.) ; m/p from BM or marginal pool Positive feedback mechanism? Collecting Enough HPCs Volume- LVL 2.5-fold increase in CFU-GM/ml processed when yield of 15L collected compared to the yield in the 1 st BV of the collection. CD34+ counts Decrease the number of procedures required to achieve the goal. Post Collection Donor Issues Platelets Each collection, a donor loses ~4x10 11 plt Plt count 30% (in product + G-CSF suppression) After 2 collections, plt <100,000 in 20-23% of donors Delayed plt recovery (as oppose to immediate in plateletpheresis donors): start to rise only >2 days; return to baseline 7-10 days post collection Donors with low platelet counts are at potential risk from bleeding and remain at risk for up to 1 week Post Collection Donor Issues WBC Mild, transient WBC 2-3 weeks post collection of 2 HPC products In 10% of donors, given G-CSF, ANC to The count can remain low 1-2 weeks Not clinically significant; no infections 8

9 Collection Donor Issues Side Effects of Mobilizing Agents Post Collection Donor Issues G-CSF Long Term Safety Agent G-CSF Common toxicities Bone pain Low grade fever Headache Injection site reaction Splenic enlargement Uncommon toxicities Splenic rupture Thrombosis (CVA, MI) Flare of autoimmune disease Precipitation of sickle cell crisis GM-CSF AMD3100 Bone pain Low grade fever Headache Injection site reaction Fluid retention Bloating Flatulence Injection site reaction Paresthesias High fever Hypotension Dizziness Premature ventricular contractions 18 Normal G-CSF Donors had Cytogenetic Studies (FISH) performed on lymphocyte samples * Found a level of asynchrony in replication for alleles associated with malignancy that resolved by day 140 * Gains or losses in chromosome 17 persisted up to 268 days Post Collection Donor Issues G-CSF long term safety (cont.) Two cases of AML occurring in first degree HLA matched donors 5 years after G-CSF administration for collecting cells for transplant in recipients with AML Summary Stem cells are the key element for successful BMT Peripheral blood is an excellent source for stem cells Different mobilization techniques exist in order to collect stem cells from peripheral blood Different collection strategies can result in better yield of the stem cells in the product Short and long term side effects always need to be considered 9