Abstract
Adipocyte dysfunction plays a critical role in the pathogenesis of metabolic diseases, including type 2 diabetes (T2D). Human induced pluripotent stem cells (hiPSCs) offer a powerful platform for generating white, beige, and brown adipocytes, supporting both disease modeling and therapeutic research. This review provides a comprehensive summary of current differentiation methods to produce three functionally mature adipocyte types from pluripotent stem cells (PSCs), including forced gene expression techniques, developmental biology-inspired approaches, and advanced three-dimensional (3D) culture systems that enhance cellular maturity and functional relevance. PSC-derived white adipocytes contribute to modeling adipocyte dysfunction not only in conditions such as insulin resistance, lipodystrophy, and premature aging but also in more complex metabolic diseases, including T2D, facilitating the investigation of disease mechanisms and the identification of novel therapeutic targets. In addition, iPSC-based models provide a robust platform for exploring genetic regulation by genome-wide association studies (GWAS)–identified variants through population genetics. This review also evaluates the therapeutic potential of iPSC-derived white, beige, and brown adipocytes in cell transplantation therapy for metabolic diseases, with a focus on engraftment potential and metabolic improvement. Enhancing the maturity and subtype specificity of PSC-derived adipocytes is expected to accelerate the development of personalized medicine and innovative therapeutic strategies for metabolic diseases.
Introduction
The global prevalence of obesity is rising 1 , contributing to an increased incidence of metabolic diseases such as type 2 diabetes (T2D), metabolic dysfunction-associated steatotic liver disease (MASLD), and coronary artery disease2,3. Obesity is characterized by excessive adipose tissue accumulation, and adipose tissue plays a critical role in maintaining systemic energy homeostasis. Adipocytes are categorized into white, beige, and brown adipocytes, each with distinct functional properties4,5. White adipocytes primarily store excess energy as lipids and secrete various adipokines that influence metabolic functions 6 . Both an excess and a deficiency of white adipose tissue (WAT), as seen in obesity and lipodystrophy, respectively, are associated with metabolic dysfunction, including T2D4,7. Brown adipocytes are thermogenic cells that produce heat through uncoupling protein 1 (UCP1)-mediated nonshivering thermogenesis, burning lipids and glucose8–11. Beige adipocytes, also known as “brite” or “inducible brown” adipocytes, emerge in WAT under cold exposure or β-adrenergic stimulation, activating UCP1 and switching to a thermogenic state5,12,13. Notably, the quantity and activity of thermogenic adipocytes are reduced in obese individuals5,9,14,15, suggesting that activation or transplantation of these cells could be a promising therapy for metabolic diseases16,17. Given the strong association between adipocyte dysfunction and metabolic disorders, studying adipocyte biology is essential for understanding the pathophysiology of these conditions.
Historically, adipocyte research has relied heavily on rodent models 18 . However, significant species-specific differences in genome, anatomical structure, function, metabolism, and drug responses complicate the translation of findings to human physiology19–22. Human adipocyte sources include primary cells—such as adipocytes, preadipocytes, and adipose-derived stem cells (ADSCs)—isolated directly from human tissue and immortalized cell lines. Primary cells maintain physiological relevance but are difficult to obtain, limited in quantity, and challenging to culture long-term. In contrast, cell lines provide a stable and scalable option but are often immortalized using genetic modifications and typically represent a single genetic background limiting their ability to reflect the diversity of human genetic backgrounds23,24. Consequently, there is a need for a more robust and genetically diverse human adipocyte model.
Human induced pluripotent stem cells (hiPSCs) provide a promising alternative for adipocyte research. iPSCs offer significant advantages, including overcoming the ethical concerns associated with human embryonic stem cells (hESCs) and providing an unlimited source of cells that can differentiate into any cell type 25 . Moreover, iPSCs retain the donor’s genetic information, enabling the generation of patient-specific iPSC lines26–28. These cells serve as a valuable platform for in vitro disease modeling, mechanistic studies, and drug discovery. When combined with advanced genome-editing technologies such as CRISPR-Cas9, iPSCs allow for the creation of isogenic cell lines to investigate the effects of specific genetic mutations on disease development29–31. In addition, iPSC-based models facilitate the functional analysis of disease-associated risk alleles identified through genome-wide association studies (GWAS)32,33.
Beyond disease modeling, iPSC-derived adipocytes show significant promise for transplantation therapies 34 . The ability to generate scalable, uniform adipocyte populations from iPSCs creates opportunities for both allogeneic and autologous transplantation. When derived from patient-specific cells, iPSCs can potentially eliminate the need for immunosuppression and reduce the risk of graft rejection. In addition, combining iPSC technology with genetic editing tools enables the transplantation of genetically corrected, healthy adipocytes, providing a novel approach for treating metabolic diseases such as lipodystrophy. The thermogenic properties of brown and beige adipocytes offer unique therapeutic potential5,17, as their transplantation could enhance energy expenditure, improve insulin sensitivity, and mitigate obesity-related metabolic dysfunctions.
This review summarizes the differentiation methods for generating white, beige, and brown adipocytes from hPSCs, highlights their utility in metabolic disease modeling and transplantation therapies, and explores their transformative potential in personalized treatment strategies. Furthermore, it discusses recent advancements in population genetics, current challenges, and future directions in the field of iPSC-derived adipocyte research.
Pluripotent stem cell-derived white, beige, and brown adipocytes
White adipocyte differentiation methods
Efficient methods to differentiate hiPSCs into functional white, brown, and beige adipocytes have been developed, enabling advanced metabolic research and therapeutic applications. Early studies on ESCs highlighted their adipogenic potential35,36, demonstrating PSCs as a viable tool for adipocyte generation. Taura et al. first demonstrated iPSC differentiation into white adipocytes using an embryoid body (EB)–based protocol, which involved transient retinoic acid (RA) treatment during EB formation and subsequent adipogenic induction on adherent plates. This approach demonstrated adipogenic potential comparable with that of hESCs 37 . Subsequently, forced gene expression strategies were introduced to enhance adipogenesis. Notably, Ahfeldt et al. expanded mesenchymal progenitor cells (MPCs) derived from EBs and applied transient overexpression of PPARG2 in a doxycycline-inducible system, significantly improving the efficiency of white adipocyte differentiation. After 7 days of suspension culture, the formed EBs were replated onto dishes, and fibroblast-like outgrowth cells were serially passaged. These fibroblast-like cells (i.e. MPCs) exhibited proliferative capacity and expressed MSC markers, and were subsequently transduced with a doxycycline-inducible PPARG2 construct. Following successful transduction, with an efficiency of nearly 98% in MPCs, adipogenic induction was initiated with doxycycline treatment for 16 days, followed by 5 days without doxycycline, resulting in over 85% of cells differentiating into mature adipocytes with transcriptional and functional profiles comparable with primary white adipocytes, including lipolysis, adiponectin secretion, de novo lipogenesis, insulin signaling, and glucose uptake 38 .
Like EB-derived MPCs, iPSC-derived mesenchymal stem cells (iMSCs) can be generated using various methods39,40. However, as observed in Ahfeldt et al.’s study, where adipogenic differentiation was extremely inefficient without forced gene expression, these iMSCs exhibit lower adipogenic potential than ADSCs or bone marrow–derived MSCs41,42. As a result, many studies report only a limited propensity of iMSCs for differentiation toward adipocyte lineages rather than robust adipogenesis43,44, making these cells less suitable for the analysis of mature white adipocyte functions.
Brown and beige adipocyte differentiation methods
Like white adipocytes, brown adipocytes can be differentiated through the forced expression of key transcription factors. Overexpression of PPARG2, CEBPB, and PRDM16 in MPCs promotes their differentiation into brown adipocytes. The resulting brown adipocytes showed increased glycerol release in response to forskolin stimulation, along with enhanced mitochondrial activity 38 . Using a similar approach, Kishida et al. 45 developed a method to generate brown adipocytes from hiPSCs by introducing PRDM16 into EBs cultured with RA. In addition, Nishio et al. focused on the bone marrow microenvironment, which enhances adipogenic differentiation, and developed a method to generate functional brown adipocytes from hiPSCs using hematopoietic cytokines. Their protocol involves an 8-day suspension culture, during which cells transiently express myoblastic markers such as MYF5, followed by adherent culture for several days, which yields adipocytes with characteristic multilocular lipid droplets 46 . To refine this approach, Oka et al. 47 developed a cytokine-free method by culturing iPSCs as size-controlled spheroids, facilitating spontaneous differentiation into a brown-like phenotype, although the molecular mechanisms underlying this differentiation method remain unclear.
Mohsen-Kanson et al. demonstrated that in an EB-based adipogenic differentiation system, RA treatment during the EB stage promotes white adipocyte formation, whereas its absence favors the emergence of adipocytes expressing brown markers. In their protocol, EBs were replated and expanded for 10 days, followed by an additional 10 days of adipogenic induction to generate white and brown adipocytes. Furthermore, they demonstrated that forced expression of Pax3 at the progenitor stage for white adipocyte differentiation, followed by adipogenic induction, resulted in a phenotypic shift toward brown adipocytes, underscoring the critical role of Pax3 in driving brown adipocyte differentiation 48 . Furthermore, following a similar approach, Hafner et al. 49 increased differentiation efficiency for brown adipocytes by inhibiting the TGFβ pathway, highlighting the significance of TGFβ signaling in brown adipocyte differentiation. In contrast, the adipocytes generated by Guénantin et al. did not express brown adipocyte markers but instead exhibited beige adipocyte-specific markers. They employed a short-term (~20-day) differentiation protocol involving mesodermal induction using BMP4 and Activin A, followed by adipogenic stimulation, resulting in beige adipocytes with functional thermogenic properties upon cAMP analog activation 50 .
Recent studies on murine adipocyte development51–57 have led to differentiation methods that more accurately recapitulate in vivo lineage trajectories. Su et al. established a stepwise differentiation protocol to generate functional beige adipocytes by directing hiPSCs through FOXF1⁺ splanchnic mesoderm. This mesoderm gives rise to an expandable, mural-like MSC population. Upon treatment with a TGF-β inhibitor and adipogenic induction, these MSCs differentiate into adipogenic precursors enriched for PDGFRα and EBF2. Further induction produces mature beige adipocytes with high UCP1 expression, uncoupled respiration, and secretion of metabolically beneficial factors 58 . In contrast, Zhang et al. established a differentiation method to generate functional brown adipocytes from hPSCs by guiding them through a paraxial mesoderm intermediate. The resulting paraxial mesoderm express FOXC1, PAX3, and MYF5, and upon adipogenic induction with browning factors, differentiate into brown adipocytes characterized by multilocular lipid droplets, high mitochondrial density, robust UCP1 expression, and enhanced glycolytic and oxidative metabolism in response to cAMP signaling 59 . Complementing these approaches, Rao et al. used single-cell RNA sequencing of developing mouse interscapular brown fat to identify a transient GATA6⁺ precursor stage. By replicating these developmental cues, they established a multistep differentiation protocol that directs hiPSCs through the dermomyotome and a GATA6⁺ brown adipocyte precursor phase. This approach yielded functional UCP1⁺ brown adipocytes with multilocular lipid droplets, abundant mitochondria, and thermogenic activity, providing a differentiation strategy closely aligned with in vivo lineage progression 60 . Collectively, these studies provide robust, developmentally informed, and scalable platforms for generating beige and brown adipocytes from hPSCs, offering valuable models for metabolic research and potential applications in cell therapy for obesity and diabetes. A schematic representation of representative adipocyte differentiation methods is shown in Fig. 1.

Differentiation methods of PSC-derived adipocytes: white, beige, and brown lineages. This figure illustrates the various methodologies for differentiating pluripotent stem cells (PSCs) into white, beige, and brown adipocytes via distinct intermediate stages and culture conditions. Dashed arrows denote suspension culture, while solid arrows indicate adherent culture methods. Adipocyte types are color-coded: yellow for white adipocytes, light brown for beige adipocytes, and dark brown for brown adipocytes. ESC: embryonic stem cells; iPSC: induced pluripotent stem cells; MPC: mesenchymal progenitor cells; WAP: white adipocyte progenitor; BAP: brown adipocyte progenitor; RA: retinoic acid; MSC: mesenchymal stem cells. Created with BioRender.com.
Three-dimensional organoid and microphysiological systems for adipocyte maturation
Recent advances have highlighted the potential of 3D organoid and microphysiological systems (MPS), namely, organ-on-a-chip platforms61–63, in enhancing the functionality and application of iPSC-derived adipocytes. Yao and Dani developed a 3D vascularized spheroid model by co-culturing hiPSC-derived brown adipocyte progenitors with human dermal microvascular endothelial cells (HDMECs), enabling the formation of prevascularized adipospheres that more closely mimic the native adipose tissue microenvironment. This coculture system not only enhanced lipid accumulation and UCP1 expression within the spheroids but also promoted extracellular matrix organization and vascular network formation, leading to improved adipocyte maturation and metabolic functionality compared with conventional two-dimensional (2D) cultures 64 . In addition, Qi et al. established a sophisticated MPS that incorporates hiPSC-derived adipocytes with macrophages and hepatocytes, enabling the reconstitution of complex tissue interactions (described in detail in the later section on Modeling Physiological Insulin Sensitivity and Resistance)65–67. These innovative 3D culture systems provide advanced platforms for modeling human metabolic diseases and hold promise for future therapeutic development.
Applications and remaining challenges of differentiation methods
While numerous methods have been developed to differentiate PSCs into white, beige, and brown adipocytes, selecting the appropriate approach should be guided by specific research objectives. For example, forced gene expression models enable relatively uniform production of mature adipocytes, making them particularly suitable for terminal differentiation phenotype analyses or comparative studies across multiple iPSC lines. In contrast, gene-free, stepwise differentiation protocols that mimic natural developmental pathways are better suited for investigating developmental processes, assessing gene function within physiological contexts, and advancing human transplantation studies.
However, these differentiation protocols are associated with several critical challenges. First, some protocols may generate immature adipocytes. Morphologically, white adipocytes derived through these methods often lack characteristic unilocular lipid droplets, while the functional properties of brown adipocytes—such as UCP1 expression and thermogenic activity—are often insufficiently characterized in comparison with primary adipocytes. This immaturity may compromise their ability to accurately model slight phenotypic changes associated with multifactorial, late-onset metabolic diseases and could limit their effectiveness in transplantation therapy.
Second, adipocyte heterogeneity remains a major challenge, particularly among white adipocytes. Subcutaneous and visceral adipocytes are known to differ significantly, often exerting opposing effects on metabolic disease risk. Subcutaneous adipose tissue is the safest and most optimal site for storing excess lipids. In contrast, increased accumulation in visceral adipose tissue is associated with a higher risk of metabolic diseases68,69. Nevertheless, current differentiation models rarely specify which adipocyte subtype is generated, posing a considerable obstacle for disease modeling and therapeutic applications. Lineage tracing studies in mice have revealed that subcutaneous and visceral adipocytes originate from distinct progenitor populations 51 . Posterior lateral plate mesoderm derivatives, labeled by HoxB6-CreERT, give rise to both subcutaneous and visceral fat 52 . The Prx1-Cre lineage predominantly contributes to subcutaneous WAT 53 , whereas Wt1-CreERT2 marks visceral depots 54 . Together, these findings suggest that subcutaneous and visceral adipocytes share a common embryonic origin in the posterior lateral plate mesoderm, which subsequently segregates into somatic mesoderm producing subcutaneous fat and splanchnic mesoderm giving rise to visceral fat. However, current differentiation protocols do not account for these mesodermal lineage differences. In addition, single-cell RNA sequencing of mouse and human adipose tissue has identified multiple subpopulations within the adipocyte progenitor pool, including adipose stem cells, preadipocytes, and anti-adipogenic progenitors, each with distinct proliferative and adipogenic potentials70–72, and has also revealed heterogeneity among mature adipocytes 73 . These findings provide insights into the various cellular states that adipocytes transition through, offering valuable reference points for the development of differentiation protocols. Future differentiation protocols should be designed to generate specific adipocyte subtypes, guided by detailed lineage maps and/or single-cell analyses to better capture the inherent cellular diversity within adipose tissues.
Metabolic disease modeling
Adipocyte dysfunction is a key contributor to various metabolic diseases4,7, and modeling the pathological states of human adipocytes in vitro is essential for disease research. Two main strategies exist for constructing adipocyte disease models: physiological modeling through culture conditions and cell–cell interactions, and genetic modeling based on disease-relevant genomic backgrounds. The following sections detail specific models of metabolic diseases, demonstrating how hPSC-based approaches enhance our understanding of adipocyte dysfunction and support personalized treatment strategies.
Modeling physiological insulin sensitivity and resistance
Dysfunction in adipocyte insulin signaling is a critical factor in the pathogenesis of metabolic diseases, including T2D 74 . Insulin resistance in adipocytes not only contributes to impaired glucose homeostasis but also precedes the onset of T2D 75 , highlighting the need for in vitro models that can accurately replicate physiological insulin responses. However, traditional in vitro adipocyte models often fail to mimic in vivo insulin signaling, largely due to nonphysiological and suboptimal culture conditions18,76. These limitations hinder mechanistic studies of insulin signaling and resistance, thereby constraining the development of effective therapeutic strategies. Friesen et al. developed a novel culture method for generating an hPSC-derived white adipocyte model that accurately mimics physiological insulin sensitivity and resistance. By optimizing nutrient conditions and treating adipocytes with a physiological sensitization medium for 5 days, they enhanced insulin-stimulated glucose uptake and AKT2 phosphorylation. They established a physiologically relevant insulin resistance model using chronic hyperinsulinemia and demonstrated TNFα treatment as an alternative approach to induce insulin resistance 77 .
As mentioned above, three recent studies utilized 3D MPS to model insulin sensitivity and resistance using hiPSC-derived white adipocytes (iADIPO) and macrophages (iMAC). In the first study, Qi et al. developed a 3D iADIPO-MPS by differentiating adipocyte progenitors into mature white adipocytes within a hydrogel matrix encapsulated in a microfluidic device. This system provided an insulin-responsive adipocyte model, characterized by enhanced adipogenic maturation with large unilocular lipid droplets, robust insulin-stimulated glucose and fatty acid uptake, and hormonally regulated lipolysis, reflecting functional competence similar to in vivo human white adipose tissue 65 . Building upon this platform, a subsequent study introduced a macrophage-adipocyte coculture model (iMAC-iADIPO-MPS), in which proinflammatory M1 macrophages were added to induce insulin resistance and dysregulated lipolysis in the adipocytes, effectively modeling chronic inflammation in white adipose tissue. In this system, M1 macrophages actively migrated into adipocyte clusters, formed crown-like structures (CLS) around damaged adipocytes, and established a reciprocal proinflammatory loop that impaired insulin signaling 66 . Expanding the complexity further, the latest study integrated adipocytes, hepatocytes, and proinflammatory macrophages into a multitissue MPS to recapitulate the crosstalk between adipose tissue and liver in metabolic disease. This system showed that adipocyte inflammation increased lipolysis and fatty acid transfer to hepatocytes, causing lipid accumulation, inflammation, and insulin resistance. These effects were reversed by semaglutide and metformin, demonstrating the platform’s utility for mechanistic studies and drug screening 67 . Together, these studies represent a logical progression from basic insulin sensitivity assays to complex multitissue models, advancing human-specific modeling of metabolic dysfunction.
Monogenic disease models
Lipodystrophy
Lipodystrophies comprise a group of rare disorders characterized by abnormal adipose tissue distribution, which lead to severe metabolic complications such as insulin resistance, hypertriglyceridemia, and hepatic steatosis78,79. Given the limitations of traditional mice models in capturing human-specific pathophysiology 80 , iPSC technology offers a powerful platform to model lipodystrophic conditions, enabling detailed investigations of adipocyte function and the development of targeted therapies.
Mori et al. in our laboratory generated iPSCs from patients with congenital generalized lipodystrophy (CGL) caused by BSCL2 (SEIPIN) mutations and differentiated them into adipocytes. These BSCL2-iPSCs showed impaired adipogenesis with reduced lipid droplet formation and disrupted adipose differentiation-related protein (ADRP) localization. The adipogenic defects were rescued by the forced expression of wild-type BSCL2, demonstrating SEIPIN’s critical role in lipid accumulation and adipocyte differentiation 81 . Friesen and Cowan established iPSCs from familial partial lipodystrophy type 2 (FPLD2) patients with the LMNA R482W mutation. The iPSC-derived adipocytes exhibited reduced adipogenic capacity, increased insulin resistance, and elevated lipolysis and autophagy 82 .
Recent advancements in genome-editing technologies have enabled the creation of isogenic models for monogenic disorders, including congenital lipodystrophies. These approaches allow for the precise introduction of pathogenic mutations into normal ES or iPS cells, as well as the correction of mutations in patient-derived iPS cells, facilitating robust disease modeling and therapeutic research. Ding et al. demonstrated this approach by introducing a frameshift mutation in the PLIN1 gene, a cause of congenital partial lipodystrophy, into hESCs using TALEN technology. The resulting adipocytes showed increased lipolysis, replicating the lipodystrophic phenotype. They further generated adipocyte models with SORT1 and AKT2 mutations, demonstrating changes in insulin-stimulated GLUT4 translocation, glucose uptake, and triglyceride metabolism 83 . This study established a robust framework for generating isogenic cellular models of metabolic diseases. By leveraging advanced genome and epigenome editing tools such as CRISPR/Cas9 84 , base editing 85 , prime editing 86 , and dCas9-based epigenetic modulators 87 , disease-associated variants identified in GWAS and epigenome-wide association study (EWAS) for T2D88-90 and obesity 91 can be precisely introduced into iPSCs. This approach enables the accurate modeling of complex metabolic diseases, providing valuable insights into disease mechanisms and advancing targeted therapy development.
Premature aging
Aging is a critical risk factor for T2D and is associated with an accumulation of senescent cells in adipose tissue. Senescent preadipocytes 92 and adipocytes93,94 promote inflammation through the senescence-associated secretory phenotype (SASP) and exhibit reduced insulin sensitivity, contributing to metabolic dysfunction95,96. Developing in vitro models of adipocyte aging is crucial to better understand age-related metabolic diseases.
Studies using hPSC models of adipogenesis, particularly those modeling premature aging syndromes, offer valuable insights into cellular senescence. Goh et al. developed a premature aging model using hPSC to study Werner syndrome and Bloom syndrome, both characterized by defective DNA damage repair and early-onset metabolic complications. They generated WRN−/− and BLM−/− hESC lines using CRISPR/Cas9 and differentiated these cells into preadipocytes. These preadipocytes exhibited a markedly increased senescence phenotype, characterized by reduced proliferation rates, shortened telomeres, elevated SA-β-gal staining, and upregulation of senescence-associated markers. Subsequent adipogenic induction of these senescent preadipocytes resulted in significantly impaired differentiation into mature adipocytes with decreased adiponectin secretion, contributing to a “lipodystrophy-like” insulin resistance phenotype 97 . This not only advances the understanding of premature aging syndromes but also highlights the potential of this model as a valuable tool for studying adipocyte aging.
Traditional in vitro models of adipocyte and preadipocyte senescence often use primary cells from aged or obese mice 92 or external stressors such as irradiation, H2O2, and doxorubicin to induce aging phenotypes93,98,99, effectively replicating age-related morphological and functional changes. Diverse approaches to induce senescence have also been successfully implemented in other iPSC-derived differentiated cells. For instance, iPSC-derived neurons have been subjected to various senescence-inducing strategies 100 , including chemical treatments (e.g. telomerase inhibitor BIBR1532 101 ), genetic manipulation (e.g. progerin overexpression 102 ), and prolonged culture conditions 103 . Applying these advanced methodologies to adipocytes could significantly improve our understanding of adipose tissue aging and its broader implications for metabolic health.
Complex metabolic disease modeling
Insulin resistance and T2D are multifactorial diseases influenced by multiple genetic and environmental factors. To elucidate the impact of polygenic risk factors specific to individual patients, iPSC technology offers a powerful platform for generating patient-specific cellular models. By differentiating iPSCs into relevant cell types, researchers can investigate disease mechanisms in a controlled in vitro environment, minimizing the confounding effects of systemic interactions present in vivo.
The use of iPSC-derived adipocytes in studies remains limited, with only an example from polycystic ovary syndrome (PCOS) patients 104 . However, more substantial progress has been made with other insulin-responsive tissues 105 . For instance, several studies have successfully recreated insulin resistance using iPSCs derived from insulin-resistant106–108 or T2D patients109–111. iPSC-derived myoblasts (iMyos) from individuals with T2D, nondiabetic individuals with insulin resistance, and insulin-sensitive controls exhibited significant differences in protein phosphorylation networks, depending on insulin resistance status 109 . Many signaling changes in insulin-resistant nondiabetic iMyos overlapped with those in cells from individuals with T2D, and donor sex further influenced cellular signaling and downstream responses 111 . Furthermore, cell-autonomous changes in gene expression associated with insulin resistance in iPSC-derived myoblasts were identified, demonstrating that these changes were regulated independently of DNA methylation 110 .
These findings underscore the potential of iPSC models to uncover cell-intrinsic mechanisms of insulin resistance, which could be particularly informative if extended to adipocytes. Generating iPSCs from T2D patient populations representing racially 112 and genetically defined disease subtypes 89 could reveal subtype-specific phenotypes in white and brown adipocytes. Such research could help elucidate the genetic and cellular bases of metabolic heterogeneity and facilitate the development of tailored therapeutic approaches.
Population genetics approach
iPSC-based models offer a powerful platform for exploring how genetic risk variants influence gene regulation in complex diseases. GWAS have identified numerous loci associated with these diseases. Notably, more than 90% of these loci reside in noncoding regions, implying that they contribute to disease through regulatory changes rather than direct protein-coding alterations113,114. However, the small effect sizes of individual variants and their cell type-specific and context-dependent impacts present challenges in deciphering their regulatory mechanisms115,116.
A promising strategy to overcome these challenges involves generating specific cell types from iPSCs and applying population genetics approaches. An early example of this approach focused on cardiometabolic diseases, where researchers reprogrammed peripheral blood cells collected from participants in the Framingham Heart Study into iPSCs, differentiating them into white adipocytes and hepatocyte-like cells (HLCs). Quantitative trait locus (QTL) analysis of 68 iPSC lines revealed that the rs12740374 variant at the 1p13 locus significantly influenced lipid accumulation and gene expression, particularly in HLCs 117 . This study established a critical proof of concept, demonstrating that iPSC-derived cells could effectively validate the functional impact of noncoding GWAS variants, highlighting the method’s potential in decoding complex genetic contributions to metabolic diseases.
Despite these advancements, iPSC-based population genetics approaches still face several challenges. Differentiation efficiency and cellular phenotypes show substantial variability across iPSC lines derived from different donors118,119, complicating the interpretation of genotype–phenotype relationships. Moreover, achieving sufficient statistical power to detect moderate-effect genetic variants typically requires relatively large cohorts—generally 20 to 80 individuals 120 . Another limitation is that traditional static QTL analyses may not adequately reflect the dynamic regulatory effects of genetic variants under varying physiological or environmental conditions. To address the challenges, innovative approaches such as dynamic QTL analyses are being developed 33 . By integrating single-cell RNA sequencing and temporal analysis, these methods can assess how genetic variants affect cellular responses to stimuli over time, offering a more nuanced understanding of regulatory networks115,116. Such dynamic analyses could significantly enhance the utility of iPSC models in population genetics.
Transplantation
White adipocytes
Lipodystrophy is characterized by abnormal loss of adipose tissue and associated systemic metabolic dysfunction. Adipose tissue transplantation has been shown to ameliorate metabolic abnormalities in lipodystrophy 121 and is also effective for soft tissue reconstruction following tumor resection 122 . Therefore, PSC-derived white adipocytes represent a promising cellular source for therapeutic applications in lipodystrophy and soft tissue regeneration.
Noguchi et al. demonstrated that white adipocytes differentiated from hiPSCs and ESCs successfully engraft after transplantation into mice. Their protocol involved EB formation, followed by adipogenic induction in adherent culture and subcutaneous transplantation of Matrigel-embedded adipocytes into immunodeficient mice. Surviving cells were detected for up to 4 weeks post-transplantation 123 . In parallel, Ahfeldt et al. 38 reported that white adipocytes induced from PSC-derived MPCs through forced expression of PPARG2 retained CEBPA expression for 4 to 6 weeks in vivo.
Although these studies demonstrated that PSC-derived white adipocytes can survive for a certain period in vivo, their effects on systemic metabolism have not been investigated, and the therapeutic potential of PSC-derived white adipocyte transplantation for metabolic diseases remains unclear. Previous studies have shown that white adipocyte transplantation may improve or exacerbate metabolic parameters, depending on the characteristics of the transplanted cells46,121,124,125. White adipocytes are classified into subcutaneous and visceral adipocytes based on their anatomical origin, each exerting distinct effects on metabolic health. Current iPSC-derived white adipocyte models fail to specify which anatomical subtype they represent. For future transplantation therapies, efforts should focus on generating subcutaneous-like “healthy” white adipocytes that provide metabolic benefits to optimize treatment outcomes for metabolic disorders34,124.
Brown and beige adipocytes
In humans, the quantity and activity of brown and beige adipocytes are reduced in individuals with obesity and aging9,14,15,126. As thermogenic adipocytes improve insulin sensitivity and metabolic health5,127,128, their transplantation represents a promising therapeutic approach for metabolic diseases16,129.
Ahfeldt et al. demonstrated the transplantation potential of hPSC-derived brown adipocytes by inducing PPARG2, CEBPB, and PRDM16 expression in MPCs. Following subcutaneous transplantation into immunodeficient mice, these cells formed ectopic fat pads with morphology characteristic of primary brown adipocytes. Notably, positron-emission tomography imaging showed high 18 FDG uptake in transplanted brown adipocytes 38 . Nishio et al. were the first to demonstrate that transplantation of PSC-derived brown adipocytes could improve systemic metabolism in mice. The transplanted BAs enhanced glucose and lipid metabolism soon after transplantation, with improvements in glucose metabolism sustained for at least 3 weeks post-transplantation 46 . In addition, Kishida et al. showed that iPSC-derived brown adipocytes could significantly reduce diet-induced obesity and insulin resistance in mice. The transplanted brown adipocytes exhibited UCP1-dependent thermogenic activity, improving glucose tolerance and lipid profile 45 . Furthermore, BAs generated by Zhang et al. engrafted within the interscapular region of recipient mice and exhibited thermogenic activity. The recipient animals showed increased metabolic activity, respiratory exchange ratio, and whole-body energy expenditure, leading to improved glucose homeostasis 59 . The generation of functional PSC-derived BAs has demonstrated potential as a therapeutic source for metabolic disease by improving glucose and lipid metabolism in transplanted mice.
As a transplantation therapy using beige adipocytes, Guénantin et al. embedded hPSC-derived beige adipocytes in Matrigel and transplanted them into mice. The transplanted cells organized into well-structured, vascularized adipose tissue. After treating the recipient mice with isoproterenol for 7 days, the transplanted adipocytes showed increased expression of thermogenic markers, along with reduced lipid droplet size and enhanced mitochondrial content, resulting in a more pronounced thermogenic phenotype 50 . These findings suggest that adjunctive therapies post-transplantation could enhance graft function and amplify therapeutic effects.
The use of reprogrammed cells from metabolic disease patients represents one potential strategy for transplantation therapy, as exemplified by Su et al. They investigated the potential of autologous iPSC-derived beige adipocytes for transplantation in patients with T2D who have impaired beige adipocyte formation. They reprogrammed primary adipogenic precursors in WAT from elderly T2D patients into iPSCs and differentiated them into beige adipocytes with enhanced thermogenic capacity. These iPSC-derived beige adipocytes also secreted factors that improved insulin sensitivity in the patients’ primary adipocytes, highlighting their potential for providing both thermogenic and antidiabetic benefits 58 . The detailed results of each adipocyte transplantation experiment were summarized in Table 1.
Metabolic effects of iPSC- and ESC-derived adipocyte transplantation in mouse models.
iPSC: induced pluripotent stem cells; ESC: embryonic stem cells.
Challenges and prospects for human transplantation
Currently, there are no reports of PSC-derived adipocyte transplantation in humans, and several critical challenges must be addressed for clinical application. First, immune rejection is a major concern for allogeneic transplantation, which typically necessitates immunosuppressive therapy. Autologous transplantation using patient-derived cells avoids immune rejection, but generating clinical-grade patient-specific iPSC lines remains costly and time-consuming 130 . A more practical alternative is the use of preestablished allogeneic iPSC banks 131 , such as the GMP-grade haplobank from CiRA in Japan, which provides 27 HLA-matched iPSC lines covering approximately 40% of the Japanese population 132 . Another promising approach to reducing immune rejection is the development of hypoimmunogenic cell lines by genetically editing cells by deleting MHC class I and class II molecules and introducing immune-evasive molecules such as CD47, CD64, HLA-E, and HLA-G 133 . Second, the risk of tumor formation remains a significant safety concern with PSC-derived cells. While no tumors have been reported in regulated clinical trials to date 134 , a case in China has been reported where a patient developed an immature teratoma and lymph node metastases after receiving autologous hiPSC-derived beta islet cells outside a regulated trial 135 . This highlights the importance of strict protocols and rigorous quality control under regulatory oversight to ensure safety. Third, the long-term survival and functional maintenance of transplanted adipocytes pose another critical challenge. Even in human adipose tissue, where approximately 10% of adipocytes turn over annually 136 , the long-term survival of PSC-derived adipocytes after transplantation remains uncertain. To improve engraftment and sustained functionality, optimizing the transplantation site, adjusting the cell dose, employing cell encapsulation techniques, and controlling the differentiation stage at transplantation are crucial137,138. In addition, obesity-related cellular stress can promote adipocyte apoptosis 139 ; thus, strategies to prevent excessive nutritional or metabolic stress after transplantation may be necessary to improve graft survival. Fourth, particularly for brown adipocyte transplantation, metabolic enhancement should be restricted to conditions of obesity or hyperglycemia. Experimental data from mouse studies show that transplanted hESC-derived brown adipocytes do not significantly reduce body weight under normal conditions as observed in mouse-derived BAT transplantations59,140. However, sustained metabolic enhancement after the normalization of body weight and metabolic function may lead to undesirable side effects. Beige adipocyte transplantation may be advantageous because their metabolic activity could potentially be controlled pharmacologically 50 , allowing metabolic effects to be activated or deactivated as clinically necessary. Resolving these challenges comprehensively will enable PSC-derived adipocyte transplantation to become a novel and effective therapeutic approach for treating metabolic diseases.
Conclusion
In an era that increasingly emphasizes the importance of human models for elucidating disease pathophysiology and advancing drug discovery, iPSC-derived differentiated cells are becoming an increasingly valuable source for research and therapeutic applications. Early adipocyte differentiation models were characterized by undefined developmental origins and relied solely on lipid accumulation and adipogenic marker expression to identify adipocytes. In contrast, more recent approaches aim to faithfully replicate developmental processes, enabling the generation of adipocytes with enhanced functionality and maturity. Utilizing adipocytes with more precisely defined identities will not only improve the resolution of disease modeling but also open new avenues for therapeutic development, including strategies targeting specific adipocyte subtypes. Furthermore, combining practical expertise gained from the rapidly advancing field of iPSC-based transplantation134,141,142 with innovative technologies such as immune-evasive iPSCs holds the potential to transform these models into practical, next-generation therapeutic strategies for metabolic diseases.
Footnotes
Ethical considerations
This manuscript is a review article and does not involve any ethical issues. All authors reviewed and approved the final version of the manuscript.
Author contributions
Y.K. designed the review structure, conducted the literature review, and drafted the manuscript. J.F. and D.Y. supervised the study and provided critical feedback and revisions. All authors contributed to the finalization of the manuscript and approved the final version.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Japan Society for the Promotion of Science KAKENHI (Grant No. 24K14720), the Grants from Japan Society of Metabolism and Clinical Nutrition (Grant No. 2023-YR004), and JST SPRING (Grant No. JPMJSP2110).
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Statement of human and animal rights
This article does not contain any studies with human or animal subjects.
Statement of informed consent
There are no human subjects in this article and informed consent is not applicable.
Data availability statement
All information in this review was obtained from previously published literature. Therefore, no new data were generated or analyzed, and all referenced data are publicly available.
