If the active material of a regenerative cell therapy is not the cell itself but the cell’s secretome, the obvious next question is what, precisely, is in that secretome. A 2017 paper led by Mellows and colleagues, with Wellbeing’s Senior Consultant Scientist Dr Steve Ray among the co-authors, set out one of the more thorough characterisations of that question that the field had produced.
The paper looked at human amniotic-fluid stem cells, a particular cell type derived from fluid surrounding the developing fetus and well established in laboratory research because of its consistent regenerative-signalling profile. The researchers cultured the cells under defined laboratory conditions, then carefully isolated the material the cells released into their environment over time. That material, the secretome, was then characterised using contemporary proteomics and small-RNA sequencing techniques.
Two numbers from the paper became the most commonly cited. The researchers identified 856 distinct proteins being secreted by the cells under the conditions tested. Many of these were known signalling molecules involved in inflammation regulation, tissue repair, angiogenesis, and immune modulation. Others had not previously been characterised as secreted at meaningful levels by this cell type. The second number was 586 distinct micro-RNAs, the short RNA sequences that influence gene expression in target cells. Each micro-RNA can affect the activity of dozens of genes, which means a few hundred micro-RNAs can collectively reshape activity across thousands of pathways.
What this told the field was not that any one of these molecules was the active agent. The point of the work was the opposite. The biological output of a stem cell is not a single growth factor or a small handful of proteins. It is a chemically diverse, contextually responsive mix in which many components contribute to the overall biological effect, often through interactions with each other rather than through any one component acting alone.
This has consequences for how cell-free preparations are thought about. A single recombinant protein, given at a defined dose, is a straightforward therapeutic object. A characterised secretome is a more complicated one. Two preparations of nominally similar source material can differ significantly in their composition depending on how the source cells were treated, what they were exposed to, how the material was harvested, and how it was preserved. The work of preparing a reproducible, characterised, biologically active preparation is not the same work as the work of preparing a recombinant protein.
The Mellows paper was specifically a study of amniotic-fluid stem cells, not of the blood-derived autologous biology that Wellbeing’s current research programme is based on. The two are different cell sources and operate under different regulatory and biological constraints. The reason the Mellows work is included here is that it shaped the thinking that informed Wellbeing’s subsequent research direction: the principles of careful characterisation, the recognition that the secretome is a complex mixture, and the need to control conditions of preparation tightly to get reproducible biological output.
Dr Ray’s involvement in the Mellows work reflects a broader pattern in his career. His scientific background spans whole-cell mesenchymal-stem-cell research, secretome characterisation, and cell-free preparation methods. Wellbeing benefits from his accumulated expertise. He is one of Wellbeing’s Senior Consultant Scientists. He is also independently active in the field through other entities he is associated with, which is the standard pattern for senior scientific advisors in this area.
For readers who want to look at the underlying paper, the Mellows work is published in the open scientific literature and is straightforward to find through standard search tools. It is not a paper aimed at general readers. It is a methodologically focused proteomics piece. But the headline finding, that 856 proteins and 586 micro-RNAs are released by these cells, is a useful piece of intuition to carry into any conversation about what a cell-free regenerative preparation actually contains.