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CD34+ Hematopoietic Stem Cells: Biology, Sourcing and Specification

CD34 is a marker of convenience that became a definition. It was identified as a surface antigen on immature haematopoietic cells, turned out to be selectable, and the population it captures has been the working definition of a haematopoietic stem cell product ever since. That history matters, because CD34 positivity and stem cell function are correlated rather than identical, and the gap between them explains several things that otherwise look inconsistent.

How to read the numbers here. Where a value is a documented minimum, an average or a program-level metric, that scope is stated with it. Product-specific lot values, availability, grade and intended use are confirmed with the scientific team.

What CD34 actually marks

CD34 is a surface glycoprotein expressed on haematopoietic stem and progenitor cells, and also on vascular endothelium and some other tissues. Within a haematopoietic preparation it enriches strongly for the cells capable of reconstituting blood lineages, which is why selecting on it works.

What it does not do is isolate a pure stem cell population. The CD34+ fraction is a mixture of true long-term stem cells and committed progenitors at various stages, with the genuinely primitive cells forming a minority of it. A CD34+ purity figure describes the fraction of cells carrying the marker, not the fraction capable of long-term reconstitution.

Where CD34+ cells come from

Source Character Practical notes
Cord blood Naive, high proliferative and engraftment potential per cell Fixed unit volume; total cell number per collection is limited
Bone marrow The original clinical source Invasive collection, which constrains research supply
Mobilized peripheral blood High CD34 yield after mobilisation Requires administering a mobilising agent to the donor
Steady-state peripheral blood Very low CD34 frequency Impractical as a primary source

OrganaBio’s peripheral blood program uses non-mobilized healthy adult donors, so CD34+ material is supplied from cord blood as HematoPAC-HSC-CB rather than from a mobilized peripheral collection.

Related product

CD34+ HSCs. Cord blood-derived CD34+ cells, released against an internal purity specification.

See cd34+ hscsAsk about availability

Why cord blood is biologically distinct

Cord blood CD34+ cells are more naive than their adult counterparts, with greater proliferative capacity and engraftment potential on a per-cell basis. That is why a cord blood unit containing far fewer total cells than a marrow harvest can still be clinically useful.

The same naivety has consequences for research. Cord blood-derived cells tolerate extensive expansion better than adult-derived cells, which matters for any protocol that needs to generate large numbers from a limited starting population. The same property is visible in cord blood NK cells and is discussed in the NK cell guide.

Reading a CD34 specification

Two numbers do most of the work and they are frequently conflated. Purity is the percentage of the delivered cells that are CD34+. Yield or content is how many CD34+ cells you actually receive. A high purity on a small number is still a small number, and experiments are planned on content rather than on percentage.

OrganaBio lists CD34+ purity for the cord blood product with the isolation approach stated, which is what makes the figure interpretable. Purity is generally lower for CD34 selection than for isolations targeting abundant populations, because the starting frequency is low and the selection has less to work with. A specification in the region of 80% or above is a normal expectation for this population rather than a weak one, and comparing it against a 95% figure for an abundant lineage is comparing two different problems.

The number to plan against. Ask for CD34+ cell content per vial alongside purity and viability. Purity alone will not tell you whether you can run the experiment.

What these cells are used for

Research applications cluster around a few areas. Haematopoiesis itself, including lineage commitment and the behavior of the progenitor compartment. Gene therapy and gene editing, where CD34+ cells are the target population for a large and growing class of approaches. Humanised mouse models, which depend on engrafting human haematopoietic cells. Expansion protocol development, where the question is how to increase numbers without losing the primitive population. And transplant-adjacent research on engraftment and homing.

What to specify when ordering

Source, since cord blood and adult-derived cells behave differently. CD34+ content per vial rather than only purity. Viability and the timepoint it refers to. Whether the material is single donor. Format and storage condition. Donor characterization, particularly HLA type where the work involves any immunological component. And grade.

OrganaBio documents cord blood-derived CD34+ HSCs and fresh whole cord blood from its perinatal program, with donor characterization including high-resolution NGS HLA typing across six genes. How to read what arrives is covered in reading a certificate of analysis.

Frequently asked questions

What are CD34+ cells?

CD34 is a surface glycoprotein expressed on haematopoietic stem and progenitor cells, and selecting on it strongly enriches for cells capable of reconstituting blood lineages. It is a marker of convenience rather than a definition of stemness.

Are all CD34+ cells stem cells?

No. The CD34+ fraction is a mixture of long-term stem cells and committed progenitors at various stages, with genuinely primitive cells forming a minority. A CD34+ purity figure describes marker expression, not reconstitution capacity.

Where do CD34+ cells for research come from?

Cord blood, bone marrow, and mobilized peripheral blood are the practical sources. Steady-state peripheral blood carries too low a frequency to be practical. OrganaBio supplies CD34+ material from cord blood, since its peripheral blood program uses non-mobilized healthy adult donors.

Why are cord blood CD34+ cells different from adult-derived ones?

They are more naive, with greater proliferative capacity and engraftment potential per cell. That is why a cord blood unit with far fewer total cells can still be useful, and why cord blood-derived cells tolerate extensive expansion better.

What is a normal CD34+ purity specification?

Purity for CD34 selection is generally lower than for isolations targeting abundant populations, because the starting frequency is low. A figure around 80% or above is a normal expectation for this population, and comparing it with a 95% figure for an abundant lineage compares two different problems.

Should I plan an experiment on CD34+ purity or content?

Content. Purity is the percentage of delivered cells carrying the marker; content is how many CD34+ cells you actually receive. A high purity on a small number is still a small number.

What are CD34+ cells used for in research?

Haematopoiesis and lineage commitment studies, gene therapy and gene editing where CD34+ cells are the target population, humanised mouse model generation, expansion protocol development, and engraftment and homing research.

Talk to OrganaBio

Working through this on a live program?

The scientific team works through sourcing and specification questions with cell therapy and research groups directly, including donor characterization, format selection and documentation scope.

Talk with the scientific team

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Andrew Larson

Managing Director, CPC Services

Andrew joins OrganaBio as a project manager with varied experience in project management, client relations, and process improvement.

Prior to OrganaBio, Andrew was a client relations manager for the cGMP nucleic acids business unit at Aldevron, coordinating and managing contracts at each stage of the contract lifecycle in support of cell and gene therapy program development. Andrew supported small- and large-scale biotechnology and pharmaceutical clients anywhere from pre-IND work through commercial supply chain establishment. Before Aldevron, Andrew was a project manager for the commercialization and business development department for Sanford Health, a worldwide hospital institution. At Sanford Health, Andrew helped manage medical device patent and prototype development efforts for employee innovations primarily in the cardiovascular, neurovascular, and software spaces. Andrew was also an engineer for Atirix Medical Systems and supported the buildout of automated analysis worksheets to streamline radiology department quality control procedures.

Andrew received his Bachelor of Science in Physics from Minnesota State University Moorhead and his Master of Science in Biomedical Engineering from the University of Minnesota. At the University of Minnesota, Andrew was part of the Center for Magnetic Resonance Research, assisting efforts to automate MRI dataset registration and workflow improvement.

Michael Dee

Associate Director, QC and Analytical Development

Michael Dee has spent the last 17 years researching the immune system. Initially studying the recombinant cytokine IL-2 and its role in T cell subset differentiation and function at the University of Miami. He also helped elucidate the lower level of TCR diversity of T regs required to prevent autoimmunity in mice. Michael also supported construction, cloning, production, purification, and testing both in vitro and in vivo a novel IL-2/IL2Rα complex currently under clinical development with BMS. Michael also was a member of the department of immunology’s program project delineating the effect of a novel Eg7GP96 heat shock protein vaccine on tumor immunity.

While at Immunity Bio (formerly Altor Biosciences), he helped to characterize over 20 novel drugs for immune modulation and treatment of cancer.  After Immunity Bio, Michael was a founding team member of HCW Biologics, where he continued his role in design and initial production and characterization of several novel biologics. He has experience with proof of principle experiments with the generation CAR-NK and CAR T cells. His research at HCW was highlighted by his discovery of a process using novel biologics to activate and expand CIML NK cells. The process and rights were sold to Wugen and is currently in Phase I clinical trials. He also is listed as an Inventor on patent number: US20210268022A1 on method of activating regulatory T cells.

Meram Alamoudi

Senior Cell Processing Specialist

Meram received her master’s degree in biomedical sciences from Barry University and bachelor’s in Biology from Palm Beach Atlantic University.

Before her position at OrganaBio, Meram conducted research at Larkin University where she worked on assessing the impact of Hurricane Maria on respiratory diseases in Puerto Rico, which provided her with insight into research investigation and analysis along with generation of grant documentation.

Valeria Beckhoff-Ferrero

Senior Bioprocess Scientist

Valeria Beckhoff Ferrero has over 8 years of experience in the fields of stem cell research and tissue engineering. Valeria received her Bachelor of Science in Biomedical Engineering, specializing in Biomaterials and Tissue Engineering, from Drexel University in Philadelphia. Valeria has expertise in problem solving and finding manufacturing solutions for isolating various types stem cells and other cell derived products from different tissues.

Before joining OrganaBio, Valeria was a lead manufacturing engineer at the Amnion Foundation. She aided in instituting a GMP infrastructure, including documentation, to manufacture clinical grade placental derived stem cells. In her role, she worked in perfecting isolation, culture, selection and cell maintenance processes for perinatal derived stem cells.

Valeria’s experience includes working as an Automation Engineer at the New York Stem Cell Foundation, where she aided in the creation and coding procedures for liquid handlers to manufacture induced pluripotent stem cells. At NYSF, Valeria researched new methods of sorting, reprogramming and differentiating iPSCs.

During her studies, Valeria worked at Thomas Jefferson University Hospital’s Radiation Oncology department, where she engineered various devices to aid in hyperthermia treatments. Additionally, Valeria co-authored multiple publications on magnetic resonance guided focused ultrasound and radiation antennas for hyperthermia treatments.

Marisa Reinoso

Director, Regional Scientific Sales

Marisa has experience leading marketing and sales life sciences programs for over a decade. Originally a lab researcher, she made the jump to marketing & sales in life sciences and never looked back.

At OrganaBio, she connects cell therapy developers on the West coast and in Asia with the healthy donor starting materials they need to develop their therapies. Prior to OrganaBio, she was the cell therapy marketing lead at Invetech, heading the launch of the company’s first cell therapy product. Marisa has led marketing programs at clinical supply companies Sherpa Clinical Packaging and PCI Pharma Services. In her spare time, Marisa enjoys traveling, eating, and pretending she’s a tennis player. She has a Bachelor of Arts in Biology from Reed College and an MBA from Portland State University.

Thelma Cela

Senior Director, Tissue Procurement

Thelma Cela is a top performing professional with over 25 years’ experience in management, leadership, business development and marketing fields with business acumen and skills in driving revenue and profit growth in multiple corporate cultures. Prior to joining OrganaBio, Thelma served as Senior Director for Health and Human Services for the Seminole Tribe of Florida. Her role had oversight for health clinics, health plan administration, the behavioral health department, and elder services. In this governmental administrative capacity, Thelma had primarily responsibility for the HHS’ divisions’ budget, capital projects, utilization management, efficiency, and efficacy.

Thelma’s prior work experiences include Vice President of Clinical Operations for OrthoNOW. In this role, she provided guidance on all clinical matters, set direction on clinical policies and procedures and monitoring healthcare policy changes. As the national Vice President of Clinical Operations, Thelma also designed, developed, and implemented guidelines and protocols and ensured compliance regarding overall patient experience.

Before joining OrthoNOW, Thelma had been recruited by Leon Medical Centers, a private healthcare company operating comprehensive medical centers to launch a new business line addressing the health and wellness of an aging population. As Director, Thelma researched, created, and launched the company’s Health Living Centers which provided first of its kind facilities in the South Florida market to offer services to the community of health aging.

Thelma has a proven track record in multiple corporate healthcare cultures having worked for Mercy Hospital where she was Senior Program Director of their Diabetes Treatment Center and Director of their Surgical Weight Loss Program. She enhanced these service lines awareness in the community, improved both lines’ clinical outcomes, and built volume growth while maintaining ongoing physician support. She served in a similar capacity for American Healthways.

Thelma earned her MBA from Miami Regional University where she graduated Cum Laude and her undergraduate degree in Psychology is from the University of Miami.

She serves on the advisory panel for Florida International University’s Women in Business Leadership Program helping future women become future business leaders through thought leadership, barrier destruction, and the power of influence.

Dominic Mancini

Vice President, Operations

Dominic Mancini brings 12 years of experience working the interfaces between Analytical Development, Process Development, Quality, and Manufacturing Science to OrganaBio. A lifelong learner, Dominic enjoys solving the many scientific and operational challenges presented in the field of cell and gene therapy.

Prior to OrganaBio, Dominic spent 8 years at Bluebird Bio as the company grew from 45 to 1200+ employees and from 1 clinical asset to a robust commercial pipeline. At Bluebird, Dominic initially supported the development and technology transfer of lentiviral vector manufacturing processes. As demand grew for lentiviral process and product characterization, Dominic led the development, qualification, transfer, and validation two commercial release methods. Dominic transitioned back to the Process Development organization to lead the vector manufacturing core team, increasing operational efficiency through a 5S implementation, process schedule intensification, and reverse technology transfer initiative. More recently, Dominic supported the build-out of bluebird’s Manufacturing Science & Technology team followed by the Data Systems & Analytics team, handling late-stage commercial asset support.

Dominic received his Bachelor of Chemical Engineering with Distinction from the University of Delaware. Dominic’s undergraduate research culminated in his thesis on heterologous expression of G-protein coupled receptors in Saccharomyces cerevisiae. After graduation, Dominic was the premier hire of the Zhou Laboratory at Brigham and Women’s hospital in Boston, MA. In three years, Dominic established an animal model of COPD and co-authored several papers with his collaborators in the Pulmonary division.

Christopher B. Goodman

Vice President, Quality & Regulatory Affairs

Christopher B. Goodman is a biopharmaceutical consultant and executive making a global impact in the cellular therapy technology arena. The scope of Christopher’s expertise encompasses Cellular Therapeutic Operations, Quality and Regulatory Affairs, Global Corporate Operations, Scientific Strategic Planning, Scientific R&D Collaborations, and Marketing & Commercialization.

Christopher recently joined OrganaBio as their Vice President of Regulatory Affairs. In this role, Christopher will be helping the company, its clients and partners navigate the complexities of the domestic and international regulatory requirements governing advanced cellular therapy products and manufacturing.

Previously, Christopher held positions with the Association for the Advancement of Blood and Biotherapies (AABB), Virgin Health Bank, Ventana Medical Systems, and Celgene.

While with AABB, he held the positions of Senior Director of New Products and Lead Quality Assessor, auditing both domestic and international organizations to known standards in an effort to promote and ensure patient quality care and manufactured product consistency and standardization within Cellular Therapy, Blood Banking, Transfusion Services, Perioperative and Donor Center industries and operations. He contributed greatly to the work of AABB’s accreditation program providing his deep breadth of knowledge and technical acumen on many committees during his tenure. His pioneering work in the realm of virtual assessments during the COVID pandemic allowed AABB to flex into the planning and execution of this novel approach to the maintenance of accreditation activities during a global travel crisis. His agile thinking and approach to planning provided as minimal disruption as possible to AABB’s customer facilities.

While working with Virgin Health Bank in the State of Qatar and the United Kingdom, Christopher advanced through a series of executive roles. He joined Virgin Health Bank as the Director of Operations, during which time he managed the successful design, and build out of a new state-of-the-art cGMP facility, the first in the Middle East. As Director and Chief Executive Officer, he directed the launch of the first Arab-centric stem cell bank, and strategically guided the organization to enhanced shareholder value and expansion across the Middle East and UK. In these roles, he also oversaw global corporate operations, research collaborations, product portfolio expansion, and regulatory framework.

Christopher managed the Detection and Chemistry Assay Development Group for Ventana Medical Systems, a global leader and innovator of tissue-based diagnostic solutions. In this role, he directed overall program goals, optimized resources, and guided technical and product direction in global regulated environments.

Prior to Ventana Medical Systems, he held the position of Director of Operations for the high-growth Cellular Therapeutics Division of Celgene. As a senior-level scientist and member of the executive team, he directed divisional operations, medical affairs and executed business and scientific strategic planning.

Danielle Smyla

Senior Director, Quality Assurance

Danielle Smyla, M.S., brings 14 years of Quality Assurance and GMP experience in the Biotechnology and Medical Device industries. Ms. Smyla is an established Quality Leader with expertise in the implementation, management and continuous improvement of Quality Management Systems for GMP operations.

Prior to joining OrganaBio, Danielle was a key member of the Quality Management team at Canon BioMedical, where she led the cross-functional development and implementation of their Quality Management System. She also managed a team of Quality Specialists and Sr. Specialists, coaching them in the implementation, management and identification of improvements to quality processes.

Ms. Smyla’s Quality-focused career is complimented by valuable hands-on experience in GMP product manufacturing, as well as R&D laboratory experimentation and formulation work in support of product development.

Danielle has earned a Master’s in Biotechnology from the Johns Hopkins University and a Bachelor of Science in Chemistry from the George Washington University.

Sarah Alter, Ph.D.

Lab Director

Sarah Alter, Ph.D., is Laboratory Director at OrganaBio, LLC, where she provides technical leadership across laboratory operations, process development, product manufacturing, and clinical sample processing services supporting cell and gene therapy developers worldwide. She brings more than 20 years of immunology and translational research experience spanning autoimmunity, oncology, and infectious disease.

Since joining OrganaBio in 2018, Dr. Alter has progressed through roles of increasing responsibility, first as Director of Immunology, leading development and manufacturing of human-derived immune cell products for immuno-oncology partners and clients; then as Senior Director of Scientific Affairs, where she served as immunology subject matter expert and shaped scientific strategy across new product launches, market analyses, and client engagements. She also served as founding Managing Director of HemaCenter, LLC, OrganaBio’s FDA-registered leukapheresis collection subsidiary, where she stood up operations, recruited the medical team, and authored governing protocols and SOPs.

Earlier in her career, Dr. Alter led preclinical R&D for IL-15–based immunotherapies at Altor BioScience (now ImmunityBio), contributing to programs that advanced into the clinic and co-authoring numerous peer-reviewed publications. She holds a Ph.D. in Immunology from the University of Miami Miller School of Medicine and an M.Sc. in Microbiology from Florida Atlantic University, and is a registered Patent Agent licensed to practice before the U.S. Patent and Trademark Office.

Carlos Carballosa, Ph.D

Vice President, Sales

Dr. Carlos Carballosa holds a doctorate in Biomedical Engineering from the University of Miami and currently leads global sales for OrganaBio as the VP of Sales. Since joining the company in 2018, Carlos has had a hand in managing all of OrganaBio’s products and services including perinatal tissue, apheresis material, and cell processing and cryopreservation support services for clinical trials.

Oscar Robles

Director, Quality Systems

Oscar Robles has over thirty years of experience in pharmaceutical and medical device industries. His main areas of expertise are in Quality Systems, Quality Assurance, Manufacturing Systems Validation, Computerized Systems Validation, implementation of GxP Computerized Systems and ERP Systems such as TrackWise, Electronic Document Management, JDEwards, SAP, and Oracle. Prior to joining OrganaBio, Oscar was a member of the Quality Management team at Apotex – Aveva Drug Delivery Systems for ten years. Oscar has earned a Master’s in Business Administration from Nova Southeastern University and a Bachelor of Science in Electrical Engineering from Florida International University.

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