ISSCA: From Stem Cells to Peptides in Regenerative Medicine

ISSCA and regenerative medicine's shift toward peptides

For more than a decade, 'regenerative' at a Latin American medical congress almost always meant stem cells. The International Society for Stem Cell Application (ISSCA), based in Miami and described by Global Stem Cells Group as its educational division³, is one of the most visible names in that story: according to its own website, it has trained physicians since 2009, reports more than 12,000 physicians trained from more than 30 countries, and in 2026 has congresses scheduled in São Paulo, Bogotá and Dubai¹. Its catalog includes courses on stem cells and exosomes¹.

What stands out is what ISSCA added: a fully online Advanced Peptide Therapy Certification with 9 modules, 52 lessons, more than 9 hours of video, materials in English and Spanish with Portuguese subtitles, and a new module on peptide-based immunotherapy². When a society with 'stem cell' in its name devotes an entire certification to peptides, it says a lot about where regenerative-medicine education is heading. This article explains why that shift is happening, what the human evidence says on each side, and how to compare them by the same standard.

Cells, exosomes and peptides: three ways to send a signal

The most honest explanation for the shift comes from cell biology. In 2017, Arnold Caplan, who had named 'mesenchymal stem cells' more than 25 years earlier, proposed renaming them 'Medicinal Signaling Cells': these cells home to sites of injury and secrete immunomodulatory and trophic factors, and it is the patient's own resident cells that build the new tissue⁴. In other words, the injected cell works mainly as a signal factory, not as a brick.

If the effect depends on what the cell secretes, the next step is logical: use the secretion. Exosomes are extracellular vesicles of about 100 nanometers that carry nucleic acids, proteins, lipids and metabolites reflecting their cell of origin⁵. One step further are peptides: short amino-acid chains with a defined sequence that act as specific signals on specific receptors. Since insulin, more than 80 peptide drugs have reached the market⁶. This is the arc many training programs follow today, ISSCA included: from the whole cell, to the message it secretes, to the signaling molecule.

What the human evidence says about stem cells

Mesenchymal cells have been in clinical trials for more than a generation, and according to Galipeau and Sensébé the results of advanced trials have fallen short of what animal models promised⁸. Part of the problem is definition: in 2006 the International Society for Cellular Therapy set minimal criteria (plastic adherence, expression of CD105, CD73 and CD90, absence of hematopoietic markers and trilineage differentiation)⁷, but those criteria do not guarantee that two products from different donors, tissues or cultures behave alike⁸.

Knee osteoarthritis is the best example, because it is one of the most heavily marketed indications. A McMaster meta-analysis of 16 randomized trials and 807 participants concluded that intra-articular mesenchymal cells probably provide little to no improvement in pain or function, with a possible increase in adverse events (RR 2.67; low certainty)⁹. Another meta-analysis, of 8 trials and 502 patients, did find significant WOMAC improvements at 6 and 12 months¹⁰. The hardest data came in 2023: a phase 2/3 trial of 480 patients compared bone marrow aspirate concentrate, stromal vascular fraction and umbilical cord cells with a corticosteroid injection, and none of the cell injections was superior to another or to the corticosteroid at 12 months; MRI did not change either¹¹.

There are real successes, but they are narrow. In December 2024 the FDA approved remestemcel-L (Ryoncil), the first mesenchymal cell therapy approved by that agency, for steroid-refractory acute graft-versus-host disease in children¹². Outside indications like that, the FDA warns that unapproved regenerative products have been linked to blindness, tumor formation and infections¹³; three patients suffered severe vision loss after intravitreal injections of so-called adipose 'stem cells'¹⁶.

Exosomes are further behind still. The FDA has stated that there are no approved exosome products and reported serious adverse events with products marketed as such¹⁴. A 2024 systematic review catalogued 471 clinical trials involving extracellular vesicles, most of them diagnostic; therapeutic trials mainly used mesenchymal-cell vesicles, and isolation and characterization methods were often not reported¹⁵. More in exosomes versus peptides.

Peptides: approved, promising and unproven

Peptides are not one block. There are three very different categories, and a good training program, whether from ISSCA or any other institution, should keep them clearly apart.

Approved, with hard outcomes. Semaglutide reduced body weight by 14.9% versus 2.4% with placebo at 68 weeks in STEP 1¹⁷, and in SELECT, with 17,604 patients with cardiovascular disease and overweight or obesity without diabetes, it reduced major cardiovascular events (HR 0.80)¹⁸. Teriparatide, a fragment of parathyroid hormone, is perhaps the best-proven 'regenerative' peptide: it builds bone, and in its pivotal trial new vertebral fractures fell from 14% with placebo to 5% and 4%¹⁹.

Promising, with some human data. Thymosin beta-4 eye drops (RGN-259) showed significant improvements in discomfort and corneal staining versus vehicle in a phase 2 trial of only 9 patients with severe dry eye²². Note that TB-500 is not the same as the full protein; we explain why in TB-500 is not thymosin beta-4.

Popular, with almost only animal data. BPC-157 is the textbook case: a 2025 systematic review gathered 36 studies, 35 preclinical and one clinical, described a half-life under 30 minutes and found no clinical safety data²⁰. A second review, searching through June 2026, found just three human studies with 30 participants in total, all of poor methodological quality and very low certainty²¹. GHK-Cu has decades of laboratory work on collagen, angiogenesis and gene expression²³, but very few controlled clinical trials. See the BPC-157 and TB-500 guide.

Standardization, purity and cost: where peptides do win

This is the most concrete advantage of peptides, and probably the practical reason behind the shift seen at ISSCA and other schools. A synthetic peptide has a known sequence, and its identity, purity and impurities are measured by HPLC and mass spectrometry, lot by lot. For synthetic generics of peptides such as glucagon, liraglutide or teriparatide, the FDA expects every new impurity between 0.10% and 0.5% to be identified, characterized and justified with immunogenicity risk testing, and considers new impurities above 0.5% unacceptable²⁴. That is what makes a certificate of analysis (COA) with verifiable numbers possible; we explain it in the peptide quality guide.

A living cell cannot be reduced to a certificate. The 2006 minimal criteria describe surface markers and differentiation capacity⁷, but biological potency depends on the donor, the tissue of origin and the culture⁸, and characterization of exosomes is often incomplete¹⁵. The practical differences in short:

• Identity: peptide = exact sequence and mass; cell = phenotype by markers and variable function⁷⁸.
• Purity: a peptide has quantifiable impurities with numeric limits²⁴; a cell product carries contamination risks during processing that the FDA explicitly describes¹³.
• Stability and logistics: a lyophilized peptide is a chemical product stored and shipped as such; cells require sterile processing and a biological cold chain, which makes manufacturing more expensive.
• Regulatory class: peptides are evaluated as drugs; cells and exosomes as biological products, with very few approvals¹²¹³¹⁴.

What ISSCA teaches today and how to combine both worlds

According to its website, ISSCA's peptide certification covers the foundations of peptide therapy, mechanisms, patient-selection logic and an immunotherapy module, with a final assessment and a verifiable certificate; ISSCA itself states that the program is educational and does not constitute medical advice². That statement matters: a certification, from ISSCA or any society, teaches a framework, but it does not replace the clinical trials that are still missing for most regenerative peptides²⁰²¹.

For a physician coming from cell therapies, the sensible combination is not 'cells plus peptides' as a package, but asking both the same questions:

• What level of evidence is this intervention at: approved, randomized trial, small human series or animal only⁹¹¹²¹?
• What is the honest comparator? In osteoarthritis, a corticosteroid matched the cells at 12 months¹¹.
• Can I verify the identity and purity of the lot (COA with HPLC and mass spectrometry)²⁴, or do I only have a label?
• Am I recording outcomes and adverse events in a way that adds up to evidence rather than testimonials?

Used this way, the two tools do not compete: cells still have specific approved indications¹², peptides bring chemical traceability²⁴ and drugs with hard outcomes¹⁷¹⁸¹⁹, and both share the same debt to controlled trials. The value of ISSCA's new peptide offering will depend on how well it helps its students tell those three categories apart.