Induced pluripotent stem cell-derived mesenchymal stem cell exosomes emerge as potent inducers of cancer cell senescence

Abstract

This editorial provides a critical commentary on the study published by Ababneh et al. Mesenchymal stem cells (MSCs) are among the most prolific producers of exosomes (Exos), nanoscale extracellular vesicles that combine tumor-homing capacity with minimal immunogenicity, no tumorigenic risk, and favorable ethical and logistical profiles compared to whole-cell therapies. Ababneh et al demonstrate that Exos derived from induced pluripotent stem cell-derived MSCs (iMSC-Exos) exert a robust and sustained anti-proliferative effect on both pancreatic (PANC1) and triple-negative breast cancer (MDA-MB-231) cells not by triggering apoptosis, but by inducing a stable senescence-like state. Strikingly, bone marrow MSC-derived Exos show inconsistent, cancer type-dependent responses, underscoring a pivotal principle that the cellular origin of Exos is not a technical detail but a decisive determinant of their biological function. This work challenges the long-standing assumption that MSC-derived Exos are therapeutically interchangeable and repositions “therapy-induced senescence”, a durable cell cycle arrest coupled with a complex secretory program, as a novel, cell-free anticancer strategy. Critical questions remain: What molecular cargoes (e.g., non-coding RNAs, senescence-associated secretory phenotype regulators) in iMSC-Exos drive this phenotype? Can this non-lytic approach avoid the inflammatory toxicity of pro-apoptotic therapies? Most crucially, will therapy-induced senescent cells be efficiently cleared by immune surveillance, or could their senescence-associated secretory phenotype inadvertently fuel tumor progression? Despite these unknowns, iMSC-Exos represent more than a new biologic: They embody a conceptual leap, positioning “therapeutic senescence” as a source-dependent, tunable modality with the potential to catalyze a new era of precision Exos-based oncology.

Key Words: Induced pluripotent stem cell-derived mesenchymal stem cells; Bone marrow mesenchymal stem cells; Exosomes; Senescence-associated secretory phenotype; Cancer cell senescence

Core Tip: This editorial emphasizes how exosomes from induced pluripotent stem cell-derived mesenchymal stem cells, not those from bone marrow, drive a potent, non-apoptotic antitumor response by inducing stable senescence in aggressive carcinomas, thereby redefining exosome source as a critical therapeutic variable and positioning senescence induction as a promising strategy for precision cancer therapy.

This editorial refers to “Cancer cell-dependent increase in senescence-like populations following exosome treatment from bone marrow and induced pluripotent stem cell-derived mesenchymal stem cells” by Ababneh et al, 2025; https://doi.org/10.4252/wjsc.v17.i11.110381.

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INTRODUCTION

Exosomes (Exos) are nanoscale extracellular vesicles (30-150 nm) that serve as critical mediators of intercellular communication, transferring a diverse cargo of proteins, lipids, and nucleic acids between cells[1,2]. In oncology, they have emerged as a highly promising platform for cell-free therapy due to their inherent tumor-homing properties, low immunogenicity, and absence of tumorigenic risk, advantages that circumvent the safety and logistical challenges associated with whole-cell transplantation[3-6]. Mesenchymal stem cells (MSCs), derived from sources such as bone marrow, adipose tissue, and umbilical cord, are among the most prolific producers of therapeutic Exos. The paracrine effects of MSCs, long attributed to secreted factors, are now increasingly recognized as being largely mediated by their Exos (MSC-Exos). These vesicles have been extensively investigated for their roles as drug carriers, immune modulators, and inducers of apoptosis in cancer cells[7-9].

However, a fundamental assumption underpinning much of this research, namely that all MSC-Exos are functionally equivalent, has begun to be challenged. The biological identity of an Exo is not generic; it is profoundly imprinted by the epigenetic, metabolic, and senescent state of its parent cell. This principle is powerfully demonstrated in the article by Ababneh et al[10], published in World Journal of Stem Cells. This study was designed to directly compare the anti-cancer effects of Exos derived from two distinct MSC sources: Conventional bone marrow-derived MSCs (BMSC-Exos) and induced pluripotent stem cell-derived MSCs (iMSC-Exos), using the aggressive, therapy-resistant cancer cell lines PANC1 (pancreatic adenocarcinoma) and MDA-MB-231 (triple-negative breast cancer) as models.

The primary objective of Ababneh et al’s study[10] was to determine whether the cellular origin of the parent MSC dictates the functional outcome of its derived Exos. Their methodology involved rigorous characterization of both MSC populations according to International Society for Cellular Therapy criteria, followed by isolation and purification of Exos via sequential ultracentrifugation. They then systematically evaluated the effects of these Exos on cancer cell proliferation, apoptosis, senescence, and invasion. The key findings revealed a striking functional divergence: While both BMSC-Exos and iMSC-Exos significantly suppressed cancer cell proliferation, this effect was not mediated by apoptosis. Instead, the primary mechanism was the induction of a stable, non-apoptotic senescence-like state, as evidenced by a significant increase in SA-β-galactosidase-positive cells. Crucially, iMSC-Exos consistently induced a robust and sustained senescent response in both cancer cell lines, with a 2.3-fold higher number of senescent PANC1 cells compared to BMSC-Exos. In contrast, BMSC-Exos exhibited inconsistent, cancer type-dependent effects, inducing senescence in MDA-MB-231 cells but actually reducing the senescent population in PANC1 cells. Furthermore, iMSC-Exos were significantly more effective at inhibiting tumor cell invasion than BMSC-Exos. The conclusion drawn by Ababneh et al[10] is paradigm-shifting: The therapeutic efficacy of MSC-Exos is not inherent to the label “MSC-Exo”, but is a direct consequence of the cellular provenance of their parent. This work definitively refutes the notion of functional interchangeability among MSC-Exos and establishes the source of the Exo as a decisive, non-negotiable variable in cancer therapy. This editorial builds upon this groundbreaking study to argue that the field must now embrace a precision framework for Exo therapeutics, where the source, manufacturing process, and functional validation are paramount. By identifying “therapy-induced senescence” as a potent, source-dependent anti-cancer mechanism, Ababneh et al[10] have not merely compared two Exo products; they have redefined the very axis upon which the next generation of cell-free oncology will be built.

SENESCENCE TURN: FROM BYSTANDER TO STRATEGY

Cellular senescence, once viewed merely as a passive barrier to immortalization, is now recognized as an active, dynamic, and secretory state with profound dual roles in cancer biology, acting both as a tumor-suppressive mechanism and, paradoxically, as a promoter of tumor progression[9,11]. This duality is largely mediated by the senescence-associated secretory phenotype (SASP), a complex mixture of cytokines, chemokines, growth factors, and proteases that can remodel the extracellular matrix, recruit immune cells, or fuel chronic inflammation and epithelial-mesenchymal transition[12,13].

The study by Ababneh et al[10] delivers a pivotal insight by demonstrating that iMSC-Exos induce a stable, non-apoptotic, SA-β-galactosidase-positive senescent state in aggressive cancer cells. This finding aligns with emerging evidence that senescence can be a primary, non-genotoxic response to external signals, repositioning it from a mere bystander effect to a central therapeutic strategy. The profound impact of this work lies in its challenge to the apoptosis-centric paradigm of cancer therapy. By inducing durable cell cycle arrest rather than immediate cell death, iMSC-Exos may offer a distinct clinical advantage: Potentially avoiding the inflammatory cascades and compensatory proliferative responses often triggered by cytotoxic agents.

However, herein lies the central tension that defines the future of this approach: Is therapy-induced senescence a definitive therapeutic endpoint, or a latent risk; a ticking time bomb? If senescent cancer cells are not efficiently cleared (a process known as senolysis), their persistent SASP could inadvertently create a pro-tumorigenic microenvironment, fostering relapse and metastasis. This critical caveat is underscored by the data of this study, which showed that BMSC-Exos actually reduced the senescent population in PANC1 cells, suggesting that the modulation of senescence is context-dependent and not universally beneficial.

Therefore, the true therapeutic value of iMSC-Exos may extend beyond simply inducing senescence; it may lie in the potential to shape the quality of the senescent state. Do iMSC-Exos elicit a beneficial SASP enriched with immunostimulatory factors like C-X-C motif ligand 10 or interleukin (IL)-15, which could enhance anti-tumor immunity? Or do they trigger a “malignant” SASP dominated by pro-inflammatory mediators like IL-6 and IL-8? This crucial question remains unanswered in the current study, representing a significant limitation. Future research must profile the specific molecular cargo (e.g., microRNAs like miR-34a, long noncoding RNAs regulating p16/p21) within iMSC-Exos to determine if they encode instructions for a therapeutically favorable senescent program. As such, while the concept is elegant, its long-term safety and efficacy hinge on resolving this fundamental ambiguity.

WHY SOURCE MATTERS: THE INDUCED PLURIPOTENT STEM CELL ADVANTAGE

The superior consistency and potency of iMSC-Exos observed by Ababneh et al[10] likely stem from the fundamentally rejuvenated biology of their parent cells. Induced pluripotent stem cell reprogramming effectively resets epigenetic aging clocks, erases donor-specific variability, and restores youthful metabolic and secretory profiles, all of which are faithfully packaged into the Exos they produce. In contrast, bone marrow MSCs are typically derived from adult donors who may harbor age-related dysfunctions, including replicative senescence, mitochondrial dysfunction, and pre-existing SASP-like secretomes. These inherent limitations of primary MSCs can contaminate their exosomal output, potentially explaining the inconsistent, cancer type-dependent effects reported in the study (e.g., reduced senescence in PANC1 cells).

This stark functional divergence between iMSC-Exos and BMSC-Exos underscores a critical limitation of relying on primary MSC sources: Heterogeneity. Donor age, health status, and culture conditions introduce significant variability, making standardized, large-scale production of clinical-grade Exos a major translational bottleneck. The work by Ababneh et al[10] compellingly argues for a shift towards the iMSC platform, which offers a scalable, genetically stable, and ethically unambiguous source for generating consistent batches of Exos under Good Manufacturing Practice conditions.

Moreover, the field has long grappled with conflicting reports on the role of MSC-Exos in cancer, with some studies showing pro-tumorigenic effects[6] and others demonstrating anti-tumor activity[14]. The findings of Ababneh et al[10] provide a unifying explanation: These discrepancies may arise not from flawed science, but from differences in the source and provenance of the MSCs used. By directly comparing two well-defined sources, this study elevates “cellular origin” from a technical footnote to a non-negotiable, first-order variable in experimental design and therapeutic development. This represents a significant conceptual leap towards precision Exo therapeutics.

CLINICAL IMPLICATIONS AND FUTURE DIRECTIONS

The non-apoptotic mechanism of iMSC-Exos presents distinct clinical advantages over traditional cytotoxic therapies. It holds the promise of a more tolerable treatment profile with reduced off-target toxicity and avoidance of acute inflammatory reactions. Furthermore, the study demonstrated a high degree of selectivity, with minimal impact on normal human dermal fibroblasts, suggesting a favorable therapeutic index. This selectivity implies that the bioactive cargo of iMSC-Exos preferentially targets signaling pathways dysregulated in cancer cells, sparing normal cellular functions.

Despite these promising in vitro results, the ultimate success of this strategy hinges on a critical factor not addressed in the current study: Senolysis. The authors acknowledge in their discussion that “further validation is required through the application of in vivo studies such as xenograft models” to understand the dynamics of senescent cell clearance within a complex physiological environment. Without efficient immune-mediated clearance, the induced senescent cancer cells could become reservoirs for disease recurrence. This gap represents the most significant limitation when translating these findings to the clinic.

Thus, the logical next step is to move beyond monotherapy and embrace rational combination strategies: (1) With senolytics: Pairing iMSC-Exos with senolytic agents (e.g., dasatinib + quercetin) to actively eliminate the senescent cancer cell burden; (2) With immunotherapies: Combining them with immune checkpoint inhibitors to boost the immune system’s ability to recognize and clear senescent cells, capitalizing on the potential immunogenicity of the SASP; and (3) With engineered Exos: Developing next-generation iMSC-Exos that are engineered to co-deliver both senescence-inducing factors and senolytic molecules, creating a self-contained one-two punch therapy.

CONCLUSION

Ababneh et al’s study[10] is a landmark contribution that does more than compare two Exo sources, it a paradigm shift. It compels the field to abandon the outdated notion of functionally interchangeable MSC-Exos and instead adopt a rigorous precision framework, where the cellular source, manufacturing process, and functional validation are paramount. Although significant challenges remain, particularly regarding in vivo validation and senolysis, iMSC-Exos represent a beacon of innovation, offering a potentially elegant and effective strategy for treating aggressive cancers in the era of precision medicine.