The retraction notice states that concerns were raised regarding the integrity of the images in the published figures after the article appeared. When the journal’s editorial team investigated, the authors failed to provide complete raw data or a satisfactory explanation. Given the concerns about the validity of the data and the absence of complete raw data, the journal concluded that retraction was the appropriate course of action. The retraction was approved by the Chief Executive Editor of Frontiers, and the authors were given an opportunity to respond before the decision was finalized.

The original paper, published on 22 May 2018 by Han and colleagues, had proposed a mechanism by which a specific microRNA could protect mesenchymal stem cells from apoptosis in an Alzheimer’s disease model. Mesenchymal stem cells, typically harvested from bone marrow, have long been explored as potential therapeutic vehicles for neurodegenerative conditions because they can home to sites of injury, secrete neuroprotective factors, and modulate inflammation. However, a persistent obstacle in cell-based therapies is that many transplanted cells die rapidly after introduction into a hostile host environment, limiting any therapeutic benefit they might provide.

MicroRNAs are short, non-coding RNA molecules, roughly 18 to 25 nucleotides in length, that regulate gene expression after transcription. They function by binding to complementary sequences in target messenger RNAs, typically within the 3′ untranslated region, which leads to mRNA degradation or translational repression. Let-7f-5p belongs to the let-7 family, one of the earliest discovered and most conserved microRNA families, known for roles in development, cell proliferation, and differentiation. The 2018 study had suggested that Let-7f-5p enhanced stem cell survival by directly targeting caspase-3, an enzyme that sits at a critical juncture in the apoptotic cascade, cleaving numerous cellular substrates once activated.

Caspase-3 is often described as the principal executioner caspase because it carries out the final dismantling of the cell. Inhibiting caspase-3 activation is a well-established strategy for reducing cell death in experimental models of ischemia, neurodegeneration, and transplant stress. The idea that a naturally occurring microRNA could be harnessed to dampen caspase-3 activity in transplanted mesenchymal stem cells was therefore an appealing therapeutic concept, and the paper attracted interest from researchers exploring ways to improve the viability of cell grafts in the brain.

The retraction highlights a recurring vulnerability in the biomedical literature: the integrity of published images. In cell biology, results are frequently communicated through micrographs, western blots, and flow cytometry plots, and the authenticity of these images underpins the credibility of the findings. When concerns arise about duplicated, manipulated, or misattributed images, journals typically request the underlying raw data. The inability or unwillingness of authors to supply complete raw data is widely regarded as a serious red flag, because it removes the possibility of independently verifying that the published figures faithfully represent the experiments described.

In this case, the investigation was conducted in accordance with Frontiers’ research integrity policies, and the journal explicitly acknowledged the contribution of Elisabeth Bik, an independent image integrity analyst whose work has been instrumental in surfacing concerns about manipulated or duplicated figures across thousands of published papers. The retraction notice records that the authors received communication regarding the retraction and had a chance to respond, and that this communication has been recorded by the publisher. This procedural transparency is intended to ensure that retraction decisions are documented and that the scientific record reflects not only the withdrawal but also the process by which it was reached.

Retractions of this kind carry practical consequences for the research community. Papers that are retracted are typically flagged in bibliographic databases, and citation practices increasingly call for authors to acknowledge retraction status when citing previously retracted work. For researchers working on microRNA-based approaches to stem cell survival, the retraction means that the specific claims of the 2018 paper can no longer be relied upon as evidence. Any future work on Let-7f-5p and caspase-3 in the context of mesenchymal stem cell transplantation in Alzheimer’s disease would need to be built on independently generated and verifiable data.

The broader lesson for the field is that the mechanisms governing cell survival in the nervous system remain a fertile area of investigation, but the path from a promising molecular observation to a robust therapeutic strategy depends on the reliability of the underlying data. Mesenchymal stem cell therapies for neurodegenerative disease continue to be explored in preclinical and clinical settings, and microRNAs remain an active area of study as potential modulators of cell fate. The retraction of this particular paper does not invalidate those broader research directions, but it does remove one specific claim from the evidence base and underscores the importance of rigorous data integrity practices.

As of the retraction date, the notice is published under a Creative Commons Attribution License and is freely accessible. The original article remains available online but is now clearly marked as retracted, ensuring that readers who encounter it will be directed to the withdrawal notice. The case serves as a reminder that scientific self-correction, though sometimes slow, is an essential mechanism for maintaining the reliability of the literature on which future discoveries and clinical advances depend.

Subject of Research: Retraction of a 2018 study on microRNA Let-7f-5p and mesenchymal stem cell survival in an Alzheimer's disease model

Article Title: Retraction: MicroRNA Let-7f-5p Promotes Bone Marrow Mesenchymal Stem Cells Survival by Targeting Caspase-3 in Alzheimer Disease Model

Article References: Retraction: MicroRNA Let-7f-5p Promotes Bone Marrow Mesenchymal Stem Cells Survival by Targeting Caspase-3 in Alzheimer Disease Model. (n.d.). https://doi.org/10.3389/fnins.2026.2023227

Image Credits: AI Generated

DOI: 10.3389/fnins.2026.2023227

Keywords: retraction, microRNA, Let-7f-5p, mesenchymal stem cells, Alzheimer's disease, caspase-3, image integrity, Frontiers in Neuroscience, research integrity, apoptosis, neurodegeneration, raw data