Cytokines in Stem Cells and Organoids: A Paradigm Shift in Drug Discovery

Cytokines are small, secreted proteins that play critical roles in immune regulation, cell signaling, and tissue homeostasis. These molecules have emerged as pivotal tools in biomedical research, especially in the fields of drug discovery and regenerative medicine. Cytokines are essential for orchestrating cellular processes such as proliferation, differentiation, and apoptosis, making them indispensable for studying disease mechanisms and therapeutic applications [1,2]. The advent of advanced in vitro models, such as induced pluripotent stem cells (iPSCs) and organoids, has significantly enhanced the utility of cytokines in mimicking complex tissue microenvironments [3]. However, the pleiotropic nature of cytokines—where a single cytokine affects multiple biological pathways—poses challenges, necessitating precise modulation to maximize their therapeutic potential [4].

Cytokines in Stem Cell Biology

Cytokines are indispensable in maintaining stem cell pluripotency and self-renewal, as well as driving their differentiation into specific lineages. iPSCs, derived from somatic cells through reprogramming [5], rely on a carefully controlled microenvironment enriched with cytokines such as FGF2, TGF-β, and BMP4 to sustain their pluripotent state [6,7]. During differentiation, cytokine signaling ensures lineage specificity by mimicking embryonic development pathways. For instance, Activin A and BMP2 guide the development of endodermal tissues, such as the liver and pancreas, while VEGF and SCF support mesodermal differentiation into hematopoietic and vascular cells [6,7]. The strategic use of cytokines also addresses the variability inherent in differentiation protocols, ensuring consistent generation of desired cell types. This has made iPSCs and organoids derived from them indispensable tools for disease modeling, personalized medicine, and regenerative therapies8. In addition to differentiation, cytokines play a role in maintaining the genomic stability and functional integrity of stem cells during expansion. Their ability to regulate key pathways like WNT and Notch further underscores their importance in stem cell research [9].

Organoids as a Cytokine-Driven Research Platform

Organoids—three-dimensional cell culture systems that mimic the structure and function of human organs—have emerged as transformative tools in drug discovery. Derived from stem cells or tissue biopsies, organoids rely heavily on cytokines to recreate organ-specific microenvironments (Fig. 1). For example, in intestinal organoids, Wnt3a and EGF promote epithelial proliferation, while BMP4 regulates maturation [10]. Similarly, VEGF and FGF2 are crucial for vascularized brain organoids, facilitating the development of functional blood vessel [11]. These cytokine-driven models provide unparalleled insights into developmental processes, disease mechanisms, and host-pathogen interactions, offering a physiologically relevant alternative to traditional 2D cultures (Table 1). The integration of organoids with cytokine signaling has enabled researchers to simulate complex conditions such as inflammation, fibrosis, and tumor progression. By leveraging cytokines like IL-6 and TNF-α, organoids can replicate inflammatory microenvironments [12,13], which are essential for studying autoimmune diseases and chronic inflammatory conditions.

Expanding the Role of Cytokines in Drug Discovery

The integration of cytokines into stem cell and organoid research has significantly advanced drug discovery by enabling more accurate, predictive, and personalized models. Cytokine-enhanced systems provide valuable platforms for drug screening, toxicity testing, and mechanistic studies.

Personalized Medicine and Disease Modeling

Patient-derived iPSCs combined with cytokine-supported organoids offer unprecedented opportunities forpersonalized medicine research. Cytokines like IL-6 and IL-1β simulate inflammatory conditions to evaluate drug responses in patient-specific contexts. For example, cystic fibrosis organoids enriched with Wnt signaling modulators enable precise testing of therapeutic candidates tailored to individual genetic profiles [14].

Immunotherapy Development

Cytokines are central to advancing immunotherapy research. Organoid models incorporating immune cells and cytokines such as IL-2 and IL-15 enable the simulation of tumor microenvironments. These systems facilitate the evaluation of immune checkpoint inhibitors, cytokine-based therapies, and adoptive T-cell strategies, providing critical insights into the dynamic interactions between tumors and the immune system [15].

High-Throughput Screening

Organoid platforms combined with cytokine-driven differentiation protocols are enabling high-throughput drug screening. For instance, liver organoids supported by VEGF and HGF are utilized in high-throughput hepatotoxicity screening, allowing for the rapid assessment of drug safety profiles during preclinical evaluations [16]. Similarly, lung organoids incorporating FGF2 and EGF play a crucial role in high-throughput respiratory disease modeling and antiviral therapy testing, enabling efficient evaluation of numerous compounds [17].

Infectious Disease Research

Cytokines are indispensable for studying infectious diseases. During the COVID-19 pandemic, cytokine-driven lung and intestinal organoids provided critical insights into SARS-CoV-2 pathogenesis, including the cytokine storm that contributes to severe disease outcomes [18].

Regenerative Medicine

Cytokines also support the application of organoids in regenerative medicine. Pancreatic organoids, guided by cytokines such as Activin A, FGF2 and IGF-17, are being explored as potential therapies for diabetes. Similarly, hepatic organoids are being developed to model liver regeneration and test cell-based therapies.

Challenges and Future Directions

While the applications of cytokines in stem cell and organoid research are expanding, several challenges persist. The pleiotropic effects of cytokines can lead to unintended off-target consequences, highlighting the need for precision engineering of cytokine formulations [4] (Fig. 2). Additionally, the high cost and batch variability of recombinant cytokines remain barriers to widespread adoption in industrial applications. Emerging solutions include the development of synthetic cytokine mimetics and engineered cytokines with enhanced specificity and stability. Advances in bioengineering, such as microfluidics and 3D bioprinting, are also poised to improve the scalability and reproducibility of cytokine-driven systems. Furthermore, integrating cytokine-based platforms with technologies like single-cell sequencing and CRISPR genome editing will enable researchers to dissect cellular heterogeneity and refine therapeutic strategies. Cytokine research continues to evolve, offering exciting opportunities to bridge the gap between basic science and clinical applications. By addressing current limitations, cytokines will remain indispensable tools in the ongoing transformation of drug discovery and regenerative medicine.

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