A Report from the 2011 World Stem Cell Summit
October 3-5, 2011 | Pasadena, California
In October 2011, an extraordinary gathering of scientific minds descended upon Pasadena, California. The World Stem Cell Summit, the largest interdisciplinary meeting of its kind, brought together over 1,500 researchers, physicians, patient advocates, and industry leaders from 25 nations 6 .
The atmosphere was electric with a sense of impending reality—the steady advance of stem cell therapies from laboratory benches to clinical bedsides. Unlike earlier conferences dominated by theoretical potential, this summit showcased tangible progress: therapies being applied to over 50 different diseases, from heart and neurodegenerative conditions to cancer and HIV/AIDS 1 . This was no longer science fiction; it was the dawn of a new medical frontier where the human body's innate capacity for healing was being harnessed to fight some of our most devastating ailments.
Researchers, physicians, and advocates
Global representation
Targeted by stem cell therapies
By 2011, stem cell science had evolved beyond basic research into a rapidly advancing therapeutic field. The summit reports highlighted a remarkable expansion of applications, with dozens of companies developing solutions at various stages of clinical use and trials 1 .
Several high-profile therapies exemplified this progress. Dendreon's Provenge demonstrated the potential of cellular immunotherapy for prostate cancer, while Geron pioneered the first-ever embryonic stem cell trials for spinal cord injury—a landmark moment for the field 1 .
One of the most important revelations presented at the summit was that stem cells heal through multiple mechanisms beyond simple cell replacement. Mesenchymal stem cells (MSCs), found in bone marrow and other tissues, emerged as particularly versatile therapeutic agents 2 .
These remarkable cells enhance tissue repair and angiogenesis through a paracrine mechanism—releasing growth factors and other signaling molecules that improve the microenvironment and modulate immune responses 2 .
Despite the exciting advances, scientists acknowledged significant hurdles remaining. A primary concern was the potential for residual pluripotent stem cells in therapeutic preparations to form teratomas—bizarre tumors containing multiple tissue types like teeth, hair, and bone 4 .
As one researcher noted, "The ability to do regenerative medicine requires the complete removal of tumor-forming cells from any culture that began with pluripotent cells" 4 .
Among the most significant announcements at the Summit came from Stanford University, where researchers revealed a potential solution to one of stem cell therapy's most dangerous side effects: teratoma formation 4 .
The problem was devilishly simple—when differentiated cells derived from pluripotent stem cells were transplanted, any remaining undifferentiated cells could turn into these chaotic tumors. As senior researcher Irving Weissman explained, "Even a single undifferentiated cell harbors the ability to become a teratoma" 4 .
Led by research associate Micha Drukker and medical student Chad Tang, the Stanford team developed an ingenious solution using antibody-based purification 4 .
They identified a previously unknown marker on undifferentiated cells called stage-specific embryonic antigen-5 (SSEA-5) and generated antibodies that specifically bound to it 4 .
| Cell Population | Teratoma Formation Frequency | Tumor Growth Characteristics |
|---|---|---|
| SSEA-5-positive cells | 7/7 experiments (100%) | Rapidly growing, typical teratomas |
| SSEA-5-negative cells | 3/11 experiments (27%) | Smaller, less-diverse growths |
| Combined antibody-purified cells | Significant reduction | Minimal or absent teratoma formation |
The researchers studied both commercially available antibodies and ones they generated themselves to identify those binding most strongly to pluripotent, but not differentiated, cells 4 .
They used a combination of antibodies—including their newly developed anti-SSEA-5 plus two others known to bind pluripotent cells—to completely separate pluripotent from differentiated cells 4 .
The critical test involved injecting the separated cell populations into mice to assess teratoma formation 4 .
The advances presented at the World Stem Cell Summit depended on sophisticated research tools that enabled scientists to identify, characterize, and work with precise stem cell populations. Flow cytometry emerged as a particularly powerful technology, allowing researchers to monitor cellular heterogeneity based on established markers and verify that stem cells maintained their pluripotency or appropriately differentiated into target cell types 9 .
| Research Tool Category | Specific Examples | Primary Function |
|---|---|---|
| Cell Dissociation Reagents | BD Accutase, trypsin | Create single-cell suspensions from adherent cultures |
| Surface Staining Antibodies | CD markers, SSEA antibodies | Identify and characterize specific stem cell populations |
| Intracellular Staining Kits | Transcription factor antibodies | Analyze internal proteins and pluripotency factors |
| Specialized Analysis Panels | BD Stemflow Kits | Pre-configured antibody combinations for specific cell types |
| Cell Sorting Technologies | Fluorescence-activated cell sorting (FACS) | Isolate pure populations of stem cells or their derivatives |
| Stem Cell Type | Positive Markers | Negative Markers | Research Applications |
|---|---|---|---|
| Pluripotent Stem Cells | SSEA-4, TRA-1-81, TRA-1-60, Alkaline Phosphatase | SSEA-1 (human) | Maintaining pluripotency, differentiation studies |
| Hematopoietic Stem Cells | CD34, CD90, CD49f (human); Sca1, c-Kit (mouse) | CD38, CD45RA, Lineage markers | Bone marrow transplantation, blood disease research |
| Mesenchymal Stem Cells | CD44, CD73, CD90, CD105 | CD11b, CD19, CD31, CD34, CD45 | Regenerative medicine, immunomodulation studies |
| Neural Stem Cells | CD15, CD24, CD184 | CD44, CD271 | Neurodegenerative disease modeling, drug screening |
A defining feature of the 2011 World Stem Cell Summit was its emphasis on collaborative, interdisciplinary approaches to advancing the field. Unlike traditional scientific conferences limited to researchers, this gathering intentionally brought together diverse stakeholders—including physicians, medical ethicists, legal scholars, and technology transfer experts—to address the complex scientific, business, legal, and regulatory challenges facing regenerative medicine 6 .
The summit also highlighted the growing role of patient advocacy in shaping research priorities and public policy. As one attendee noted, scientists were increasingly recognizing their responsibility to not only present facts but to interpret them for the public and policymakers: "Scientists should not just stick to the facts. They should present the facts and then based on the facts, voice their opinions" .
The presentations at Cedars-Sinai's sessions exemplified the "bench-to-bedside" approach that was becoming increasingly central to the field's progress 6 . Researchers like Clive Svendsen provided updates on work into causes and treatments for amyotrophic lateral sclerosis (ALS) and Parkinson's disease, while Eduardo Marbán presented clinical studies of stem cells for heart regeneration 6 .
The institutional infrastructure supporting this translation was also expanding. The Cedars-Sinai Regenerative Medicine Institute highlighted its core facility for producing pluripotent stem cells from adult patient skin biopsies, noting that "these cells have the potential to both model and treat many different types of human diseases" 6 .
The 2011 World Stem Cell Summit presented a field at a pivotal juncture—no longer defined by hypothetical potential but by steady, measurable progress toward clinical applications. The mood was optimistic yet realistic, acknowledging both the significant advances and the considerable work still required.
What emerged most clearly was that stem cell science had evolved from a solitary discipline into a collaborative enterprise requiring coordination across multiple domains. The "unique combination of an outstanding hospital and rapidly growing research mission" at institutions like Cedars-Sinai exemplified the integrated approach needed to move therapies from laboratory to clinic 6 .
As the field continued to advance, this model of close collaboration between basic scientists, clinicians, industry partners, and patient advocates promised to accelerate the delivery of regenerative solutions to patients worldwide. The steady advance reported at the 2011 summit wasn't just about individual discoveries—it was about building an entire ecosystem capable of turning scientific promise into therapeutic reality.