Direct in vivo application of induced pluripotent stem cells is feasible and can be safe

iPSC-derived exosomes promote angiogenesis in naturally aged mice

Heterochronic parabiosis has shown that aging individuals can be rejuvenated by a youthful circulatory system; however, the underlying mechanisms remain unclear. Here, we evaluated the effect of exosomes isolated from mouse induced pluripotent stem cells (iPSCs) on angiogenesis in naturally aged mice. To achieve this, the angiogenic capacity of aortic ring, the total antioxidant capacity (TAOC), p53 and p16 expression levels of major organs, the proliferation of adherent bone marrow cells, and the function and content of serum exosomes in aged mice administered iPSC-derived exosomes were examined. Additionally, the effect of iPSC-derived exosomes on injured human umbilical vein endothelial cells (HUVECs) was assessed. The angiogenic capacity of aortic rings and clonality of bone marrow cells from young mice were significantly higher than those from aged mice; moreover, the organs of aged mice had a higher expression of aging genes and lower total TAOC. However, in vitro and in vivo experiments showed that the administration of iPSC-derived exosomes significantly improved these parameters in aged mice. The synergistic effect of both in vivo and in vitro treatments of aortic rings with iPSC-derived exosomes improved the angiogenic capacity of aortic rings from aged mice to levels similar to that of young mice. Compared with untreated aged mice, serum exosomal protein content and their promoted effect on endothelial cell proliferation and angiogenesis were significantly higher in untreated young mice and aged mice treated with iPSC-derived exosomes. Overall, these results showed that iPSC-derived exosomes may rejuvenate the body by anti-aging the vascular system.

Nitric oxide-mediated the therapeutic properties of induced pluripotent stem cell for paraquat-induced acute lung injury

The mortality rate associated with acute lung injury (ALI) and its severe form, acute respiratory distress syndrome, is high. Induced pluripotent stem cell (iPSC) therapy is a potential treatment method for ALI, but its therapeutic efficacy is limited in injured lungs. Nitric oxide (NO) has various physiological actions. The current study investigated the effect of iPSCs pretreated with NO donors in paraquat (PQ)-induced ALI mouse model. Male C57BL/6 mice were intraperitoneally injected with PQ, followed by infusion of phosphate-buffered saline, iPSCs, L-arginine pretreated iPSCs, or Nitro-L-arginine methylester (L-NAME) pretreated iPSCs through the tail veins. Histopathological changes, pulmonary microvascular permeability, and inflammatory cytokine levels were analyzed after 3 or 28 d. The effects on iPSC proliferation, migration, and adhesion were evaluated in vitro. More L-arginine-pretreated iPSCs were selectively trafficked into the injured pulmonary tissue of mice with LPS-induced ALI, drastically diminishing the histopathologic changes and inflammatory cytokine levels (IL-1β and IL-6). There was also markedly improved pulmonary microvascular permeability and pulmonary function. The NO inhibitor abolished the protective effects of iPSCs. In addition, the ability of L-arginine to promote the proliferation and migration of iPSCs was decreased by L-NAME pretreatment, suggesting that NO might mediate the therapeutic benefits of iPSC. The improvement of the iPSC physiological changes by the endogenous gaseous molecule NO reduces lung injury severity. L-Arginine represents a pharmacologically important strategy for enhancing the therapeutic potential of iPSCs.

Deficiency of interleukin-6 receptor ameliorates PM2.5 exposure-induced pulmonary dysfunction and inflammation but not abnormalities in glucose homeostasis

BACKGROUND

Ambient fine particulate matter (PM_2.5) exposure increases local and systemic interleukin-6 (IL-6). However, the pathogenic role of IL-6 signalling following PM_2.5 exposure, particularly in the development of pulmonary dysfunction and abnormal glucose homeostasis, has hardly been investigated.

RESULTS

In the study, IL-6 receptor (IL-6R)-deficient (IL-6R^-/-) and wildtype littermate (IL-6R^+/+) mice were exposed to concentrated ambient PM_2.5 (CAP) or filtered air (FA), and their pulmonary and metabolic responses to these exposures were analyzed. Our results demonstrated that IL-6R deficiency markedly alleviated PM_2.5 exposure-induced increases in lung inflammatory markers including the inflammation score of histological analysis, the number of macrophages in bronchoalveolar lavage fluid (BALF), and mRNA expressions of TNFα, IL-1β and IL-6 and abnormalities in lung function test. However, IL-6R deficiency did not reduce the hepatic insulin resistance nor systemic glucose intolerance and insulin resistance induced by PM_2.5 exposure.

CONCLUSION

Our findings support the crucial role of IL-6 signalling in the development of pulmonary inflammation and dysfunction due to PM_2.5 exposure but question the putative central role of pulmonary inflammation for the extra-pulmonary dysfunctions following PM_2.5 exposure, providing a deep mechanistic insight into the pathogenesis caused by PM_2.5 exposure.

Knockout of integrin β1 in induced pluripotent stem cells accelerates skin-wound healing by promoting cell migration in extracellular matrix

Background

Induced pluripotent stem cells (iPSCs) have the potential to promote wound healing; however, their adhesion to the extracellular matrix (ECM) might decrease iPSC migration, thereby limiting their therapeutic potential. Integrin β1 (Itgb1) is the major integrin subunit that mediates iPSC-ECM adhesion, suggesting that knocking out Itgb1 might be an effective method for enhancing the therapeutic efficacy of iPSCs.

Methods

We knocked out Itgb1 in mouse iPSCs and evaluated its effects on the therapeutic potential of topically applied iPSCs, as well as their underlying in vivo and in vitro mechanisms.

Results

The Itgb1-knockout (Itgb1-KO) did not change iPSC pluripotency, function, or survival in the absence of embedding in an ECM gel but did accelerate wound healing, angiogenesis, blood perfusion, and survival in skin-wound lesions. However, embedding in an ECM gel inhibited the in vivo effects of wild-type iPSCs but not those of Itgb1-knockout iPSCs. Additionally, in vitro results showed that Itgb1-knockout decreased iPSC-ECM adhesion while increasing ECM-crossing migration. Moreover, ECM coating on the culture surface did not change cell survival, regardless of Itgb1 status; however, the in vivo and in vitro functions of both Itgb1-knockout and wild-type iPSCs were not affected by the presence of agarose gel, which does not contain integrin-binding sites. Knockout of Integrin α4 (Itga4) did not change the above-mentioned cellular and therapeutic functions of iPSCs.

Conclusions

Itgb1-knockout increased iPSCs migration and the wound-healing-promoting effect of topically applied iPSCs. These findings suggest the inhibition of Itgb1 expression is a possible strategy for increasing the efficacy of iPSC therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03085-7.

Gene-editing, immunological and iPSCs based therapeutics for muscular dystrophy

Muscular dystrophy is a well-known genetically heterogeneous group of rare muscle disorders. This progressive disease causes the breakdown of skeletal muscles over time and leads to grave weakness. This breakdown is caused by a diverse pattern of mutations in dystrophin and dystrophin associated protein complex. These mutations lead to the production of altered proteins in response to which, the body stimulates production of various cytokines and immune cells, particularly reactive oxygen species and NFκB. Immune cells display/exhibit a dual role by inducing muscle damage and muscle repair. Various anti-oxidants, anti-inflammatory and glucocorticoid drugs serve as potent therapeutics for muscular dystrophy. Along with the above mentioned therapeutics, induced pluripotent stem cells also serve as a novel approach paving a way for personalized treatment. These pluripotent stem cells allow regeneration of large numbers of regenerative myogenic progenitors that can be administered in muscular dystrophy patients which assist in the recovery of lost muscle fibers. In this review, we have summarized gene-editing, immunological and induced pluripotent stem cell based therapeutics for muscular dystrophy treatment.

Induced Pluripotent Stem Cells (iPSCs) Provide a Potentially Unlimited T Cell Source for CAR-T Cell Development and Off-the-Shelf Products

Chimeric antigen receptor T (CAR-T) cell therapy has been increasingly conducted for cancer patients in clinical settings. Progress in this therapeutic approach is hampered by the lack of a solid manufacturing process, T lymphocytes, and tumor-specific antigens. T cell source used in CAR-T cell therapy is derived predominantly from the patient's own T lymphocytes, which makes this approach impracticable to patients with progressive diseases and T leukemia. The generation of autologous CAR-T cells is time-consuming due to the lack of readily available T lymphocytes and is not applicable for third-party patients. Pluripotent stem cells, such as human induced pluripotent stem cells (hiPSCs), can provide an unlimited T cell source for CAR-T cell development with the potential of generating off-the-shelf T cell products. T-iPSCs (iPSC-derived T cells) are phenotypically defined, expandable, and as functional as physiological T cells. The combination of iPSC and CAR technologies provides an exciting opportunity to oncology and greatly facilitates cell-based therapy for cancer patients. However, T-iPSCs, in combination with CARs, are at the early stage of development and need further pre-clinical and clinical studies. This review will critically discuss the progress made in iPSC-derived T cells and provides a roadmap for the development of CAR iPSC-derived T cells and off-the-shelf T-iPSCs.

Chronic Obstructive Pulmonary Disease and the Cardiovascular System: Vascular Repair and Regeneration as a Therapeutic Target

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide and encompasses chronic bronchitis and emphysema. It has been shown that vascular wall remodeling and pulmonary hypertension (PH) can occur not only in patients with COPD but also in smokers with normal lung function, suggesting a causal role for vascular alterations in the development of emphysema. Mechanistically, abnormalities in the vasculature, such as inflammation, endothelial dysfunction, imbalances in cellular apoptosis/proliferation, and increased oxidative/nitrosative stress promote development of PH, cor pulmonale, and most probably pulmonary emphysema. Hypoxemia in the pulmonary chamber modulates the activation of key transcription factors and signaling cascades, which propagates inflammation and infiltration of neutrophils, resulting in vascular remodeling. Endothelial progenitor cells have angiogenesis capabilities, resulting in transdifferentiation of the smooth muscle cells via aberrant activation of several cytokines, growth factors, and chemokines. The vascular endothelium influences the balance between vaso-constriction and -dilation in the heart. Targeting key players affecting the vasculature might help in the development of new treatment strategies for both PH and COPD. The present review aims to summarize current knowledge about vascular alterations and production of reactive oxygen species in COPD. The present review emphasizes on the importance of the vasculature for the usually parenchyma-focused view of the pathobiology of COPD.

Tumor-associated macrophages derived from cancer stem cells

Macrophages are the most abundant immune cells in the microenvironment of solid tumors. The present study displayed histological and immunohistochemical analyses of a malignant tumor model developed from cancer stem cells (CSCs) converted from human induced pluripotent stem cells (hiPSCs) in a cancer microenvironment prepared from the conditioned medium (CM) of a pancreatic cancer cell line. We focused on the localization and the origin of tumor-associated macrophages (TAMs), To the best of our knowledge this may be the first study to suggest the potential differentiation of CSCs to TAMs. hiPSCs were converted into CSCs in the presence of CM from PK8 cells. CSCs were then transplanted in vivo and formed primary tumors. Primary cultures for these tumors were serially transplanted again to obtain secondary tumors. Secondary tumors exhibited histopathological features of malignancy. Cells derived from tumors maintained the expression of endogenous stemness markers and pancreatic CSCs markers. Simultaneously, high immunoreactivity to anti-mouse CD68, anti-human CD68, CD206 and CD11b antibodies were detected revealing that the tumor tissue derived from CSCs was enriched for macrophages which can originate from both human and mouse cells. The model of CSCs highlighted the possibility of CSCs to differentiate into TAMs.

Induced Pluripotent Stem Cells Attenuate Acute Lung Injury Induced by Ischemia Reperfusion via Suppressing the High Mobility Group Box-1

Pulmonary endothelial cell injury is a hallmark of acute lung injury. High-mobility group box 1 (HMGB1) can modulate the inflammatory response via endothelial cell activation and release of inflammatory molecules. Thus, we tested whether induced pluripotent stem cells (iPSCs) can alleviate ischemia/reperfusion (I/R) induced lung injury, and, if so, whether HMGB1 mediates the effect in a male C57BL/6 mouse model. Intravenously injected iPSCs into mice 2 h after I/R showed a significant attenuation of lung injury (assessed by lung mechanics, edema, and histology) 24 h after reperfusion (compared with controls), along with decreases in HMGB1, phosphorylated nuclear factor-κB, inflammatory cytokines [interleukin (IL)1β, IL6 and tumor necrosis factor-α], and the activation of endothelial cells. Furthermore, these effects of iPSCs can be mimicked by blocking HMGB1 with an inhibitor in vivo and in vitro. We conclude that iPSCs can be a potential therapy for I/R-induced lung injury. These cells may exert therapeutic effects through blocking HMGB1 and inflammatory cytokines.

Induced pluripotent stem cells attenuate chronic allogeneic vasculopathy in an integrin beta-1-dependent manner

This study aimed to determine the mechanism of isogeneic-induced pluripotent stem cells (iPSCs) homing to vascular transplants and their therapeutic effect on chronic allogeneic vasculopathy. We found that integrin β1 (Intgβ1) was the dominant integrin β unit in iPSCs that mediates the adhesion of circulatory and endothelial cells (ECs). Intgβ1 knockout or Intgβ1-siRNAs inhibit iPSC adhesion and migration across activated endothelial monolayers. The therapeutic effects of the following were examined: iPSCs, Intgβ1-knockout iPSCs, iPSCs transfected with Intgβ1-siRNAs or nontargeting siRNAs, iPSC-derived ECs, iPSC-derived ECs simultaneously overexpressing Intgα4 and Intgβ1, iPSCs precultured in endothelial medium for 3 days (endothelial-prone stem cells), primary aortic ECs, mouse embryonic fibroblasts, and phosphate-buffered saline (control). The cells were administered every 3 days for a period of 8 weeks. iPSCs, iPSCs transfected with nontargeting siRNAs, and endothelial-prone stem cells selectively homed on the luminal surface of the allografts, differentiated into ECs, and decreased neointimal proliferation. Through a single administration, we found that iPSCs trafficked to allograft lesions, differentiated into ECs within 1 week, and survived for 4-8 weeks. The therapeutic effect of a single administration was moderate. Thus, Intgβ1 and pluripotency are essential for iPSCs to treat allogeneic vasculopathy.

Intracellular calcium current disorder and disease phenotype in OBSCN mutant iPSC-based cardiomyocytes in arrhythmogenic right ventricular cardiomyopathy

Obscurin participates in the development of striated muscles and maintenance of the functional sarcoplasmic reticulum. However, the role of obscurin in arrhythmogenic right ventricular cardiomyopathy (ARVC) is not well understood. We aimed to study the novel obscurin mutations in the pathogenesis of ARVC and the underlying mechanisms. Methods: We generated induced pluripotent stem cells (iPSC) through retroviral reprogramming of peripheral blood mononuclear cells isolated from a 46-year-old female diagnosed with ARVC, carrying a mutation in OBSCN. The cells differentiated into functional iPSC-based cardiomyocytes (iPSC-CMs), whose phenotype was determined by transmission electron microscopy, electrophysiological description, immunofluorescence staining, and Oil Red O staining. Molecular characterization was performed by bioinformatic analyses, and identification by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. Results: ARVC-iPSC-CMs mutation in OBSCN showed significant accumulation of lipids, increased pleomorphism, irregular Z-bands, and increased L type calcium currents. Functional enrichment analysis identified pathways involved in focal adhesion and structure formation; the adipocytokines and PPAR signaling pathways were also activated in the ARVC group. Moreover, our results from ultra-high-resolution microscopy, qRT-PCR and Western blotting confirmed that the mutant OBSCN protein and its anchor protein, Ank1.5, showed structural disorder and decreased expression, but there was increased expression of junctional protein N-Cadherin. Further analysis revealed the gene expression of other desmosomal proteins in ARVC-iPSC-CMs was also decreased but some adipogenesis pathway-related proteins (PPARγ, C/EBPα, and FABP4) were increased. Conclusion: A novel frameshift mutation in OBSCN caused phenotypic alteration accompanied by disrupted localization and decreased expression of its anchoring protein Ank1.5. Furthermore, there was an accumulation of lipids with an increase in fatty fibrosis area and myocardial structural disorder, possibly leading to dysrhythmia in calcium channel-related myocardial contraction. These observations suggested the possibility of attenuating ARVC progression by therapeutic modulation of OBSCN expression.

Mesenchymal stem cell-derived extracellular vesicle-based therapies protect against coupled degeneration of the central nervous and vascular systems in stroke

Stem cell-based treatments have been suggested as promising candidates for stroke. Recently, mesenchymal stem cells (MSCs) have been reported as potential therapeutics for a wide range of diseases. In particular, clinical trial studies have suggested MSCs for stroke therapy. The focus of MSC treatments has been directed towards cell replacement. However, recent research has lately highlighted their paracrine actions. The secretion of extracellular vesicles (EVs) is offered to be the main therapeutic mechanism of MSC therapy. However, EV-based treatments may provide a wider therapeutic window compared to tissue plasminogen activator (tPA), the traditional treatment for stroke. Exosomes are nano-sized EVs secreted by most cell types, and can be isolated from conditioned cell media or body fluids such as plasma, urine, and cerebrospinal fluid (CSF). Exosomes apply their effects through targeting their cargos such as microRNAs (miRs), DNAs, messenger RNAs, and proteins at the host cells, which leads to a shift in the behavior of the recipient cells. It has been indicated that exosomes, in particular their functional cargoes, play a significant role in the coupled pathogenesis and recovery of stroke through affecting the neurovascular unit (NVU). Therefore, it seems that exosomes could be utilized as diagnostic and therapeutic tools in stroke treatment. The miRs are small endogenous non-coding RNA molecules which serve as the main functional cargo of exosomes, and apply their effects as epigenetic regulators. These versatile non-coding RNA molecules are involved in various stages of stroke and affect stroke-related factors. Moreover, the involvement of aging-induced changes to specific miRs profile in stroke further highlights the role of miRs. Thus, miRs could be utilized as diagnostic, prognostic, and therapeutic tools in stroke. In this review, we discuss the roles of stem cells, exosomes, and their application in stroke therapy. We also highlight the usage of miRs as a therapeutic choice in stroke therapy.

Diminished expression of major histocompatibility complex facilitates the use of human induced pluripotent stem cells in monkey

BACKGROUND

Stem cells, including induced pluripotent stem cells (iPSCs), have tremendous potential in health care, though with several significant limitations. Each of the limitations, including immunogenicity, may block most of the therapeutic potentials. Beta2 microglobulin (B2M) and MHC II transactivator (CIITA) are critical for MHC I and II, respectively. MHCs are responsible for immunogenic recognition.

METHODS

B2M and CIITA were knocked out from human iPSCs, either separately or simultaneously. The effects of single or dual knockout of B2M and CIITA on iPSC properties were evaluated in a xenogeneic model of human-to-monkey transplantation.

RESULTS

B2M or CIITA knockout in human induced pluripotent stem cells (iPSCs) diminishes the expression of MHC I or II alleles, respectively, without changing iPSC pluripotency. Dual knockout was better than either single knockout in preserving the ability of human iPSCs to reduce infiltration of T and B lymphocytes, survive, and promote wound healing in monkey wound lesions. The knockouts did not affect the xenogeneic iPSC-induced infiltration of macrophages and natural killer cells. They, however, decreased the iPSC-promoted proliferation of allogeneic peripheral blood mononuclear cells and T lymphocytes in vitro, although not so for B lymphocytes isolated from healthy human donors. Although the dual knockout cells survived long enough for suiting therapeutic needs, the cells eventually died, possibly due to innate immune response against them, thereby eliminating long-term risks.

CONCLUSIONS

Having these iPSCs with diminished immunogenicity-recognizable to allogeneic recipient may provide unlimited reproducible, universal, standardized "ready-to-use" iPSCs and relevant derivatives for clinical applications.

Clinical-Grade Human Pluripotent Stem Cells for Cell Therapy: Characterization Strategy

Human pluripotent stem cells have the potential to change the way in which human diseases are cured. Clinical-grade human embryonic stem cells and human induced pluripotent stem cells have to be created according to current good manufacturing practices and regulations. Quality and safety must be of the highest importance when humans' lives are at stake. With the rising number of clinical trials, there is a need for a consensus on hPSCs characterization. Here, we summarize mandatory and 'for information only' characterization methods with release criteria for the establishment of clinical-grade hPSC lines.

Intracellular Reactive Oxygen Species Mediate the Therapeutic Effect of Induced Pluripotent Stem Cells for Acute Kidney Injury

Aims

Treatment for acute kidney injury (AKI) is challenging. Induced pluripotent stem cells (iPSCs) have great therapeutic potential. This study sought to determine whether iPSCs attenuate AKI and the role of reactive oxygen species (ROS).

Results

We intravenously injected isogenic iPSCs into mice 2 h after renal ischemia-reperfusion injury (IRI). The cells were selectively trafficked to ischemia/reperfusion-injured kidney where they decreased kidney ROS and inflammatory cytokines and improved kidney function and morphology. Pretreating the cells with ROS inhibitors before administration decreased iPSC engraftment and abolished the protective effect of iPSCs. In contrast, pretreating iPSCs with hydrogen peroxide increased iPSC engraftment and therapeutic effect. Although the intravenously administered iPSCs trafficked to the IRI kidney, the cells did not differentiate into proximal or distal tubular epithelial cells. In vitro, the capabilities of the iPSC-released substances to promote proliferation and decrease apoptosis of renal epithelial cells were increased by ROS pretreatment of iPSCs. Moreover, pretreatment of the iPSCs with ROS inhibitor had the opposite effect. Similarly, moderate concentrations of ROS increased while ROS inhibitors decreased iPSC mobility, adhesion to the extracellular matrix, and mitochondrial metabolism. Innovation and Conclusion. iPSCs decreased renal ischemia/reperfusion injury mainly through iPSC-released substances. The therapeutic effect, mitochondrial metabolism, mobility, and kidney trafficking of iPSCs were ROS dependent.

Modeling Parkinson's Disease Using Induced Pluripotent Stem Cells

Parkinson's disease (PD) is the second most common neurodegenerative disease. The molecular mechanisms of PD at the cellular level involve oxidative stress, mitochondrial dysfunction, autophagy, axonal transport, and neuroinflammation. Induced pluripotent stem cells (iPSCs) with patient-specific genetic background are capable of directed differentiation into dopaminergic neurons. Cell models based on iPSCs are powerful tools for studying the molecular mechanisms of PD. The iPSCs used for PD studies were mainly from patients carrying mutations in synuclein alpha (SNCA), leucine-rich repeat kinase 2 (LRRK2), PTEN-induced putative kinase 1 (PINK1), parkin RBR E3 ubiquitin protein ligase (PARK2), cytoplasmic protein sorting 35 (VPS35), and variants in glucosidase beta acid (GBA). In this review, we summarized the advances in molecular mechanisms of Parkinson's disease using iPSC models.

Genome-wide interaction target profiling reveals a novel Peblr20-eRNA activation pathway to control stem cell pluripotency

Background: Long non-coding RNAs (lncRNAs) constitute an important component of the regulatory apparatus that controls stem cell pluripotency. However, the specific mechanisms utilized by these lncRNAs in the control of pluripotency are not fully characterized.

Methods: We utilized a RNA reverse transcription-associated trap sequencing (RAT-seq) approach to profile the mouse genome-wide interaction targets for lncRNAs that are screened by RNA-seq.

Results: We identified Peblr20 (Pou5F1 enhancer binding lncRNA 20) as a novel lncRNA that is associated with stem cell reprogramming. Peblr20 was differentially transcribed in fibroblasts compared to induced pluripotent stem cells (iPSCs). Notably, we found that Peblr20 utilized a trans mechanism to interact with the regulatory elements of multiple stemness genes. Using gain- and loss-of-function experiments, we showed that knockdown of Peblr20 caused iPSCs to exit from pluripotency, while overexpression of Peblr20 activated endogenous Pou5F1 expression. We further showed that Peblr20 promoted pluripotent reprogramming. Mechanistically, we demonstrated that Peblr20 activated endogenous Pou5F1 by binding to the Pou5F1 enhancer in trans, recruiting TET2 demethylase and activating the enhancer-transcribed RNAs.

Conclusions: Our data reveal a novel epigenetic mechanism by which a lncRNA controls the fate of stem cells by trans-regulating the Pou5F1 enhancer RNA pathway. We demonstrate the potential for leveraging lncRNA biology to enhance the generation of stem cells for regenerative medicine.

Deciphering Role of Wnt Signalling in Cardiac Mesoderm and Cardiomyocyte Differentiation from Human iPSCs: Four-dimensional control of Wnt pathway for hiPSC-CMs differentiation

Differentiation of cardiomyocytes (CMs) from human induced pluripotent stem cells (hiPSCs) is critically dependent upon the regulation of the Wnt signaling pathway. The mechanisms remain unclear with regard to the dose and timing of each differentiation inducer, and the interaction of the inducers that regulate the Wnt in mesendoderm specification to cardiac mesoderm. Consequently, it remains far from optimal in differentiation efficiency and consistency from hiPSC lines to CMs. Here, we have carefully deciphered the role of Wnt signaling pathway manipulation on mesoderm specification in a dosage and time dependent manner. To examine the hypothesis of that fate specification of hiPSC-CMs differentiation is dictated by temporal and spatial factors that regulate Wnt, we evaluate hiPSC-CM differentiation with: (1) two-phase modulation of Wnt, (2) dosage variant of GSK3β inhibitors, (3) treatment with insulin, and (4) 3-dimentional suspension culture environment on iPSC-CM differentiation. The results highlight the importance of mesendoderm specification to cardiac mesoderm, which needs precisely regulation of Wnt in a dosage dependent and temporal on/off manner. This temporal regulation dictates the final efficiency and purity of derived cardiomyocytes. After the initial activation of Wnt signaling pathway to generate mesendoderm, the maintenance of Wnt signaling at an appropriate dose is critical to direct the cell fate into cardiac mesoderm. Otherwise, lower Wnt signals lead to definitive endoderm and higher Wnt signals induce presomitic mesoderm differentiation. The precisely specification of cardiac mesoderm results in not only greater than 90% of cTnT+ cardiomyocytes but also high cardiomyocytes yield under both monolayer and suspension culture conditions. Thus, the current findings provide critical insights to decipher the temporal mechanism of Wnt activation in regulation of hiPSC-CMs differentiation, and more importantly provide the guidelines for the consistent and high-yield and high-quality hiPSC-CMs production in cardiovascular research.

Enhanced wound healing promotion by immune response-free monkey autologous iPSCs and exosomes vs. their allogeneic counterparts

Background

Comparing non-inbred autologous and allogeneic induced pluripotent stem cells (iPSCs) and their secreted subcellular products among non-human primates is critical for choosing optimal iPSC products for human clinical trials.

Methods

iPSCs were induced from skin fibroblastic cells of adult male rhesus macaques belonging to four unrelated consanguineous families. Teratoma generativity, host immune response, and skin wound healing promotion were evaluated subsequently.

Findings

All autologous, but no allogeneic, iPSCs formed teratomas, whereas all allogeneic, but no autologous, iPSCs caused lymphocyte infiltration. Macrophages were not detectable in any wound. iPSCs expressed significantly more MAMU A and E of the major histocompatibility complex (MHC) class I but not more other MHC genetic alleles than parental fibroblastic cells. All topically disseminated autologous and allogeneic iPSCs, and their exosomes accelerated skin wound healing, as demonstrated by wound closure, epithelial coverage, collagen deposition, and angiogenesis. Allogeneic iPSCs and their exosomes were less effective and viable than their autologous counterparts. Some iPSCs differentiated into new endothelial cells and all iPSCs lost their pluripotency in 14 days. Exosomes increased cell viability of injured epidermal, endothelial, and fibroblastic cells in vitro. Although exosomes contained some mRNAs of pluripotent factors, they did not impart pluripotency to host cells.

Interpretation

Although all of the autologous and allogeneic iPSCs and exosomes accelerated wound healing, allogeneic iPSC exosomes were the preferred choice for “off-the shelf” iPSC products, owing to their mass-production, with no concern of teratoma formation.

Fund

National Natural Science Foundation of China and National Key R&D Program of China.

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Autologous but not allogeneic rhesus macaque iPSCs generate teratomas.

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Non-inbred allogeneic but not autologous iPSCs attract lymphocytes.

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Both autologous and allogeneic iPSCs and their exosomes promote wound healing.

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Both autologous iPSCs and exosomes promote better wound healing than their allogeneic counterparts.

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iPSCs lost their pluripotency in vivo. Exosomes did not impart pluripotency to host cells.