Mesenchymal stem cell-based cell-free strategies: safe and effective treatments for liver injury

Interaction of neuropilin-1 and hepatocyte growth factor/C-Met pathway in liver fibrosis progression in hepatocyte-specific NRP-1 knockout mice

BACKGROUND

Hepatocyte growth factor (HGF)/c-Met signaling critically influences liver fibrosis, but its interaction with neuropilin-1 (NRP-1) in hepatocytes remains unclear. We investigated the role of hepatocyte-specific NRP-1 deletion in liver fibrosis progression and its relationship with the HGF/c-Met pathway.

METHODS

Hepatocyte-specific NRP-1 knockout mice were generated using the Cre-lox system, and liver fibrosis was induced by carbon tetrachloride injections or a methionine- and choline-deficient diet. Fibrosis severity, hepatocyte injury, and cytokine secretion were evaluated via histology, biochemical assays, and molecular analyses in isolated hepatocytes. In vitro experiments were conducted in primary hepatocytes and Huh7 cells using lentiviral overexpression and knockdown of NRP-1. Chromatin immunoprecipitation and dual-luciferase reporter assays were performed to analyze transcription factor binding to the NRP-1 promoter.

RESULTS

Hepatocyte NRP-1 expression increased significantly during liver fibrosis and was positively correlated with HGF/c-Met expression and fibrosis severity. In vivo, NRP-1 inhibition reduced extracellular matrix accumulation and abnormal angiogenesis in Alb-Cre NRP-1f/f mice. In vitro, NRP-1 blockade inhibited c-Met activation and reduced transforming growth factor-beta and vascular endothelial growth factor secretion in hepatocytes. NRP-1 functioned as a co-receptor for HGF/c-Met, with HGF upregulating NRP-1 expression at transcript and protein levels. NRP-1 promoted fibrosis through the Met/extracellular signal-regulated kinase pathway. Furthermore, HGF increased retinoic acid receptor alpha expression, promoting NRP-1 transcription.

CONCLUSIONS

HGF-induced upregulation of hepatocyte NRP-1, mediated by RARA binding to its promoter, drives liver fibrosis through c-Met pathway activation, highlighting NRP-1 as a potential therapeutic target for liver fibrosis.

From Cells to Exosomes: a Review of Non-Surgical Biotherapeutic-Based Strategies for Liver Regeneration in the Face of End-Stage Diseases

Liver diseases, such as hepatitis, cirrhosis, and liver cancer, pose significant public health challenges, ranking as the twelfth leading cause of death globally. Given the liver's critical functions in metabolism, detoxification, and biosynthesis, its impairment can lead to severe consequences, often resulting in end-stage liver failure. Although liver transplantation is regarded as the definitive intervention for advanced liver disease, factors such as a shortage of donors and potential surgical complications necessitate the investigation of non-surgical regenerative medicine alternatives. This manuscript provides a comprehensive review of innovative non-surgical therapies aimed at liver regeneration, with an emphasis on both cell-based and cell-free approaches. It examines the contributions of various stem cell populations, including mesenchymal stem cells, hematopoietic stem cells, and induced pluripotent stem cells, in facilitating liver repair through mechanisms of differentiation and paracrine signaling. Furthermore, it explores the therapeutic potential of exosomes and conditioned media derived from stem cells as biotherapeutic agents in the context of regenerative medicine. By elucidating the mechanisms that underpin liver regeneration, this study aspires to inform the development of effective therapeutic strategies to address liver diseases and slow their progression. By elucidating the underlying mechanisms of liver regeneration, this study aims to contribute to the development of effective therapeutic strategies to address liver diseases and slow their progression.

The Ameliorative Effect of Adipose-Derived Mesenchymal Stem Cells and Their Exosomes in Non-alcoholic Steatohepatitis by Simultaneously Enhancing Autophagic Flux and Suppressing Endoplasmic Reticulum Stress

Background

Due to the scarcity of treatment options, managing the progression of non-alcoholic fatty liver disease (NAFLD) from steatosis to cirrhosis necessitates innovative approaches. This study focused on endoplasmic reticulum (ER) stress, apoptosis, and autophagy as key mechanisms in NAFLD pathogenesis. It also highlighted the potential of adipose-derived mesenchymal stem cells (AD-MSCs) and their exosomes as promising therapeutic options.

Methods

The study was conducted at the Department of Regenerative Medicine, Shiraz University of Medical Sciences, (Shiraz, Iran) from November 2021 to December 2023. The mice (n=32) were divided into four groups: control, high-fat diet (HFD) without treatment, HFD with AD-MSCs treatment, and HFD with AD-MSCs-derived exosomes groups. The mice were fed HFD for 8 weeks. They received MSC and exosomes for the last 3 weeks. One week after the final injection, mice were tested for serum testing, stereological analysis, and real-time polymerase chain reaction (RT-PCR). The data were analyzed using the Graph-Pad Prism software by one-way analysis of variance (ANOVA) with Tukey analysis as a post hoc comparison between groups. P<0.05 indicated a significant difference.

Results

AD-MSCs-exosomes significantly reduced ER stress indicators (IRE1α [P=0.0001], PERK [P=0.0006], ATF6 [P=0.0001], and GRP78 [P=0.0001]), apoptosis markers (Bax [P=0.005] and Cas3 [P=0.001]), and autophagic flux markers (P62 [P=0.0001] and LC3B/A [P=0.003]).

Conclusion

In this investigation, AD-MSCs-exosomes significantly restored autophagy and suppressed unfolded protein response (UPR) pathways in the early stages of NAFLD.

Transforming Myofibroblasts Into Lipid-Filled Cells to Treat Dupuytren Disease

PURPOSE

Transforming myofibroblasts (MFs) into adipocyte-like cells may be a viable option for treating Dupuytren disease. Human Dupuytren MFs (DMFs) and adipose-derived stem cells (ASCs) cocultured in the presence of platelet-rich plasma (PRP) reprogrammed into lipid-laden cells. This treatment also reduced fibrosis markers in vivo. We aimed to determine whether this treatment transformed DMFs into adipocyte-like cells in vivo and characterize the PRP factors contributing to this transformation.

METHODS

Dupuytren MFs and normal human dermal fibroblasts were transplanted into the forepaws of rats (Rowett Nude [rnu/rnu]). Two months later, the paws were treated with saline, ASCs + PRP, or Clostridium histolyticum (clinical comparison) once a week for three treatments. The paw tissue was harvested 1 week after each treatment and subjected to Masson trichrome staining, collagen I and III, α-smooth muscle actin (SMA), and perilipin detection by immunohistochemistry. Dupuytren MFs were cocultured with ASCs and PRP or insulin-like growth factor I (IGF-I) or IGF-I-depleted PRP. In addition, the IGF-I receptor was inhibited. Oil Red O or boron-dipyrromethene detected lipid-laden cells.

RESULTS

Rodent paws implanted with DMFs showed enhanced α-SMA expression, imbalanced collagen III:I ratio, and reduced adipocytes compared with normal human dermal fibroblasts. After treatment with ASCs + PRP, DMF paws demonstrated reduced α-SMA, a balanced collagen III:I ratio, and a replenishment of adipocytes. Dupuytren MFs treated with ASCs + IGF-I transformed into adipocyte-like cells in vitro, which was validated by IGF-I-depletion and IGF-I receptor inhibition.

CONCLUSIONS

Adipose-derived stem cells + PRP reduce fibrosis markers and induce adipocyte renewal in vivo. As a PRP component, IGF-I works with ASCs to transform DMFs into adipocyte-like cells in vitro.

CLINICAL RELEVANCE

Identifying an active factor in PRP that synergizes with ASCs to transform DMFs into adipocyte-like cells may contribute to finding a novel therapeutic for Dupuytren disease. Such a treatment may allow for less-extensive surgical intervention coupled with therapeutic injection to reduce the recurrence of Dupuytren disease.

High-yield BMSC-derived exosomes by the 3D culture system to enhance the skin wound repair

Wound defects pose a substantial challenge in clinical practice, often resulting in prolonged healing times and an elevated risk of infection. Insufficient vascularization is a critical factor that adversely affects wound healing. Exosomes obtained from bone mesenchymal stem cells (BMSC-exos) have demonstrated significant promise in accelerating tissue repair by promoting angiogenesis. However, their limited yield and suboptimal biological functions impede widespread clinical application in enhancing wound healing. Prior research has indicated that 3D cultures can boost exosome secretion when compared to conventional 2D cultures. However, the currently prevalent 3D culture methods often necessitate expensive equipment or cumbersome procedures. This study investigates a cost-effective and user-friendly 3D culture system developed using gelatin methacrylate (GelMA). Our findings indicate that a 5% concentration of GelMA provides an optimal environment for the 3D culture of BMSCs. Furthermore, we observed that 3D culture significantly delays the senescence of BMSCs, thereby creating favorable conditions for the sustained production of exosomes. Additionally, 3D cultivation has the potential to boost exosome secretion and enhance their angiogenic capabilities. In vivo experiments further confirmed that BMSC-exos from a 3D environment exhibit enhanced capabilities to promote wound healing. These results suggest that GelMA-based 3D cultures offer a novel strategy for both industrial production and clinical application of exosomes.

Stem Cells from Human Exfoliated Deciduous Teeth-Derived Exosomes for the Treatment of Acute Liver Injury and Liver Fibrosis

Mesenchymal stem cells (MSCs) play a crucial role in regenerative medicine due to their regenerative potential. However, traditional MSC-based therapies are hindered by issues such as microvascular obstruction and low cell survival after transplantation. Exosomes derived from MSCs (MSC-Exo) provide a cell-free, nanoscale alternative, mitigating these risks and offering therapeutic potential for liver diseases. Nonetheless, the functional variability of MSCs from different sources complicates their clinical application. Stem cells derived from human exfoliated deciduous teeth (SHED) offer advantages such as ease of procurement and robust proliferative capacity, but their secretome, particularly SHED-Exo, remains underexplored in the context of liver disease therapy. This study analyzed MSC-Exo from various sources via small RNA sequencing to identify differences in microRNA profiles, aiding in the selection of optimal MSC sources for clinical use. SHED-Exo was subsequently tested in an acute liver injury model, showing notable regenerative effects, including enhanced hepatocyte proliferation, macrophage polarization, and reduced inflammation. Despite strong liver-targeting properties, the rapid hepatic clearance of SHED-Exo limits its effectiveness in chronic liver diseases. To address this challenge, a GelMA-based hydrogel was developed for in situ delivery, ensuring sustained release and enhanced antifibrotic efficacy, providing a promising strategy for chronic liver disease management.

One-step engineered mesenchymal stem cell-derived exosomes against hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury (IRI) is an important factor affecting the prognosis of patients undergoing surgery. Exosomes derived from mesenchymal stem cells (MSC-EXOs) are widely used and play a therapeutic role in hepatic IRI. However, natural exosomes lack liver-targeting ability and have low bioavailability. In this study, MSC-EXOs were simply modified with OPDEA-PCL or liver-targeting DSPE-PEG2000-Galactose, forming OPDEA-PCL-modified MSC-EXOs (OP-EXOs) or DSPE-PEG2000-Galactose-modified MSC-EXOs (GPEG-EXOs). In mouse hepatic IRI model, OP-EXOs and GPEG-EXOs both significantly reduced alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) levels in serum after hepatic IRI, alleviating liver injury. Transcriptomic and proteomic analyses showed that OP-EXOs and GPEG-EXOs reduced hepatic IRI by downregulating the expression of S100A8, S100A9, SELP, and ANXA2 in the liver following IRI. This study opens a new paradigm for the treatment of hepatic IRI using engineered MSC-EXOs with the potential to improve the prognosis of liver surgery.

MiR-222-3p loaded stem cell nanovesicles repair myocardial ischemia damage via inhibiting mitochondrial oxidative stress

AIMS

Mitochondrial oxidative stress (MOS) is a key contributor to poor cardiac function and a major driver of myocardial ischemia-reperfusion injury (MIRI). Our previous research demonstrated that stem cell-derived nanovesicles (NVs) enhanced cardiac function following ischemia-reperfusion (I/R) injury, although the underlying mechanisms remain unclear. We constructed and characterized miR-222-3p-loaded NVs.

MATERIALS AND METHODS

An in vitro hypoxia-reoxygenation (H/R) model was established using H9C2 cardiomyocytes. Mitochondrial oxidative respiratory function was assessed using Seahorse XF technology, while mitochondrial reactive oxygen species (mtROS) levels were quantified via flow cytometry. Additional assessments included mitochondrial permeability transition pore (mPTP) status, mitochondrial membrane potential, and mitochondrial DNA (mtDNA) integrity. An in vivo H/R model was developed using C57BL/6 mice. The therapeutic effects of NVs on MOS reduction and cardiac function improvement were evaluated through Masson's staining, immunofluorescence, echocardiography, transmission electron microscopy (TEM), and positron emission tomography/computed tomography (PET/CT).

KEY FINDINGS

RNA immunoprecipitation (RIP) confirmed that miR-222-3p directly targets cyp1a1. Overexpression of miR-222-3p or knockdown of cyp1a1 significantly improved mitochondrial activity in cardiomyocytes and conferred protection against I/R injury. Conversely, overexpression of cyp1a1 abrogated the protective effects of miR-222-3p. In vivo, NV treatment enhanced cardiac function, reduced MOS, and improved mitochondrial respiratory capacity in MIRI model mice. NV treatment, via miR-222-3p-mediated suppression of cyp1a1, mitigates MOS, enhances mitochondrial respiratory function, and improves cardiac outcomes in MIRI models.

SIGNIFICANCE

These findings provide a foundational basis for the clinical translation of NV-based therapies.

Mechanisms and aetiology-dependent treatment of acute liver failure

This review compiles the mechanisms of acute liver failure (ALF) as well as the current and potential therapeutic approaches, including aetiology-specific treatment, and the issues encountered with such approaches. On a cellular level, ALF is characterized by massive hepatocyte death due to different types of cellular demise. Compensatory hyperplasia and functional recovery are possible when the regenerative capacity is sufficient to sustain hepatic function. ALF has a high mortality of about 30% and can lead to death in a very short time despite maximum therapeutic intervention. Besides aetiology-specific therapy and intensive care, the therapeutic option of emergency liver transplantation has significantly improved the prognosis of patients with ALF. However, due to limiting factors such as organ shortage, many patients die on the waiting list. In addition to graft assessment, machine perfusion may have the potential to recondition marginal organs and thus expand the organ donor pool.

Targeting the tumor microenvironment with mesenchymal stem cells based delivery approach for efficient delivery of anticancer agents: An updated review

Drug delivery to cancer cells continues to present a major therapeutic challenge. Mesenchymal stem cells (MSCs) possess an intrinsic ability to migrate specifically to tumor tissues, making them promising candidates for targeted drug delivery. Evidence from preclinical studies indicates that MSCs loaded with therapeutic anti-cancer agents exhibit considerable anti-tumor activity. Moreover, several clinical trials are currently evaluating their effectiveness in cancer patients. The integration of MSCs with synthetic nanoparticles (NPs) enhances their therapeutic potential, particularly through the use of cell membrane-coated NPs, which represent a significant advancement in the field. This review systematically investigates the tumor microenvironment, the sources of MSCs, the tumor homing mechanisms, and the methods of loading and releasing anticancer drugs from MSCs. Furthermore, cutting-edge strategies to improve the efficacy of MSCs based drug delivery systems (DDS) including the innovative use of MSC membrane coated nanoparticles have been discussed. The study concludes with an overview of the therapeutic use of MSCs as drug carriers, including a detailed analysis of the mechanisms by which MSCs deliver therapeutics to cancer cells, enabling targeted drug delivery. It aims to elucidate the current state of this approach, identify key areas for development, and outline potential future directions for advancing MSCs based cancer therapies.

Biomimetic Extracellular Vesicles Based on Composite Bioactive Ions for the Treatment of Ischemic Bone Disease

Extracellular vesicles (EVs) have demonstrated considerable potential in the treatment of ischemic bone diseases, such as glucocorticoid-induced osteonecrosis of the femoral head (GIONFH). However, the clinical application of EVs faces challenges such as low yield, poor bioactivity, and lack of targeting. Herein, we have developed a platform of multiengineered extracellular vesicle mimetics (EVMs) to address these challenges. By stimulating mesenchymal stem cells (MSCs) with multibioactive ions from TS (Trisilicate, a mixture of calcium silicate, magnesium silicate, and strontium silicate), we obtained endogenously modified TS-MSCs. From these, we further prepared a large quantity of bioactive EVMTS-MSCs through a straightforward extrusion method. Moreover, by integrating metabolic glycoengineering with click chemistry strategies, alendronate (ALN) was surface-modified on EVMTS-MSCs to further prepare ALN-EVMTS-MSCs. The engineered ALN-EVMTS-MSCs demonstrated bone-targeting effects, promoting osteogenesis and angiogenesis. This promoting effect is attributed to the rich presence of miR-21 in the TS-modified EVM, which further silences PTEN to activate the PI3K/AKT signaling pathway, thereby enhancing osteogenesis and angiogenesis. Our treatment strategy for ischemic bone diseases is based on a multiengineered, biomaterial-inspired, metabolic glycoengineering, and click chemistry-based platform of EVM. This study also provides an enhanced understanding of the development and application of engineered vesicles in disease treatment.

Mesenchymal stem cells-derived exosomes alleviate liver fibrosis by targeting Hedgehog/SMO signaling

BACKGROUND & AIMS

Despite increasing knowledge regarding the cellular and molecular mechanisms of liver fibrogenesis, there is currently no approved drug for the treatment of liver fibrosis. Mesenchymal stem cells (MSCs) are multipotent progenitor cells representing an attractive therapeutic tool for tissue damage and inflammation. This study was designed to determine the protective effect and underlying mechanism of human umbilical cord-derived MSCs (UC-MSCs) on thioacetamide-induced liver fibrosis.

METHODS

Liver fibrosis was induced in mice by intraperitoneal injection of thioacetamide (TAA). Some mice were then given injection of UC-MSCs or UC-MSCs-derived exosomes (UC-MSCs-Exo) via the tail vein. Liver tissues were collected for histologic analysis.

RESULTS

We found that administration of UC-MSCs significantly reduced serum alanine aminotransferase and aspartate aminotransferase levels, and attenuated hepatic inflammation and fibrosis. Moreover, the therapeutic effect of UC-MSCs-derived exosomes was similar to that of UC-MSCs. Intriguingly, UC-MSCs-Exo treatment downregulated the expression of smoothened (SMO), a fundamental component of Hedgehog signaling which plays a critical role in fibrogenesis, and subsequently inhibited the activation of hepatic stellate cells, a central driver of fibrosis in experimental and human liver injury. Furthermore, the anti-inflammatory and anti-fibrotic effects of UCMSCs- Exo was reversed by the SMO agonist SAG treatment in mice.

CONCLUSION

Our findings suggest that UC-MSCs-Exo exert therapeutic effects on liver fibrosis, at least in part, through inhibiting the Hedgehog/SMO signaling pathway.

RGDSP-functionalized peptide hydrogel stimulates growth factor secretion via integrin αv/PI3K/AKT axis for improved wound healing by human amniotic mesenchymal stem cells

The wound healing process involves communication among growth factors, cytokines, signaling pathways, and cells in the extracellular matrix, with growth factors acting as key regulators. Although stem cells can promote wound healing by secreting diverse growth factors, their therapeutic potential is hindered by poor survival and engraftment. Mimicking the stem cell-matrix interactions can improve stem cell survival, regulate their fate, and even enhance their paracrine effects. This study investigated the use of composite RGDmix hydrogel, which can support the survival and proliferation of human amniotic mesenchymal stem cells (hAMSCs), and effectively increase the expression of various growth factors, thereby promoting wound re-epithelialization, angiogenesis, and epidermal maturation. At last, the specific role of integrin αv and PI3K/AKT signaling pathways in the secretion of growth factors were examined by silencing them in vitro and in vivo. Results suggested that the RGDmix hydrogel improved the secretion of growth factors by hAMSCs through the RGDSP/integrin αv/PI3K/AKT axis, thereby enhancing the therapeutic effect in wound healing.

Secretome of human amniotic membrane stem cells promote recovery and testicular functions through modulating SIRT1/NRF2/TNF-α pathway in mice testicular torsion: An experimental study

Background

Testicular ischemia/reperfusion injury, a significant result of testicular torsion, can lead to the risk of male infertility.

Objective

The current study aimed to evaluate the effect of human amniotic membrane-derived mesenchymal stem cells (hAMSCs) secretome on testicular torsion/detorsion (T/D) in mice.

Materials and Methods

All the experiments were performed in the Anatomy Department of Tehran University of Medical Sciences, Tehran, Iran, during the period of March 2023 to December 2023. 40 male NMRI mice (5-7 wk, 25-30 gr) were randomized into: 1) the sham group: mice received sham operations with no other interventions, 2) T/D group, 3) negative control group; torsion detorsion + intratesticular injection of Dulbecco's Modified Eagle Medium/Nutrient Mixture F-12, and 4) the T/D group + hAMSCs secreted factors. Serum testosterone levels, hematoxylin and eosin staining, and sperm quality parameters were used to evaluate the therapeutic effects of hAMSCs secreted factors on the testicular structure and function. Tissue oxidative stress was measured by determining malondialdehyde, superoxide dismutase, catalase, and glutathione peroxidase-1. Nuclear factor erythroid 2-related factor 2, Kelch-like ECH-associated protein 1, NAD-dependent deacetylase sirtuin-1, tumor necrosis factor-alpha and tumor protein P53 mRNA expressions were assessed in testis via real-time polymerase chain reaction.

Results

The results showed that hAMSCs secreted factors alleviated testicular T/D injury by attenuating oxidative stress, inflammatory response, and apoptosis via modulating the sirtuin-1/ nuclear factor erythroid 2-related factor 2/tumor necrosis factor-alpha signaling pathway.

Conclusion

hAMSCs secreted factors increased antioxidative, anti-inflammatory, and antiapoptotic properties which consequently increased testosterone levels, spermatogenesis, and sperm quality parameters.

Exosomal miRNA-21 derived from umbilical cord mesenchymal stem cells inhibits microglial overactivation to counteract nerve damage

BACKGROUND

Traumatic brain injury (TBI) is a major cause of neurological disability, and current treatments have limited effectiveness. Recent studies have emphasized the potential of exosomes derived from umbilical cord mesenchymal stem cells (UC-MSCs-Exo) in TBI treatment, but the molecular mechanisms underlying their therapeutic effects are not fully understood.

METHODS AND RESULTS

In this study, UC-MSCs-Exo was isolated using ultracentrifugation and intraventricularly injected to TBI rat model. The neurofunctional motor function of the rats was evaluated using the modified neurological severity score (mNSS), and the activation of microglia was assessed through immunofluorescence detection of IBA1 expression levels. Additionally, we established an in vitro neuroinflammatory model using BV2 microglia to investigate the effects of UC-MSCs-Exo and miRNA-21. Our findings indicate that UC-MSCs-Exo promote neurological recovery in TBI rats and inhibit excessive microglia activation. Furthermore, UC-MSCs-Exo highly expresses miRNA-21 and inhibited the proliferation, migration, and release of inflammatory mediators of BV2 microglia by transporting miRNA-21.

CONCLUSIONS

The present study suggests that the promotion of neurological recovery in TBI rats by UC-MSCs-Exo may be attributed to the inhibition of excessive microglia activation through miRNA-21.

miR-200a-3p-enriched MSC-derived extracellular vesicles reverse erectile function in diabetic rats by targeting Keap1

BACKGROUND

The administration of mesenchymal stem cells (MSCs) through intracavernous injection is a potential therapeutic approach for managing diabetes mellitus-induced erectile dysfunction (DMED). However, pulmonary embolism and tumorigenicity are fatal adverse events that limit the clinical application of MSCs. In this study, we examined the therapeutic efficacy and potential mechanism of MSC-derived extracellular vesicles (MSC-EVs).

METHODS

In this study, forty 8-week-old male SpragueDawley (SD) rats were utilised. In the control group, ten rats were administered an intraperitoneal injection of PBS. STZ (60 mg/kg) was intraperitoneally injected into the remaining rats to establish a diabetes mellitus (DM) model. Afterwards, the diabetic rats were divided into three groups at random: the DM group (intracavernosal injection of PBS), the EVs group (intracavernosal injection of MSC-EVs), and the EVs-200a group (intracavernosal injection of miR-200a-3p-enriched extracellular vesicles). Erectile function was determined by measuring intracavernous pressure in real time and utilising electrical stimulation of the cavernous nerves. The smooth muscle content was evaluated through the investigation of penile tissue using immunofluorescence staining, Masson's trichrome staining, and western blotting after euthanasia. Superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH) levels in the corpus cavernosum were measured via ELISA. In vitro, hydrogen peroxide (H2O2) was used to induce oxidative stress. The viability of corpus cavernosum smooth muscle cells (ccSMCs) incubated with or without H2O2 was measured using a CCK8 assay. Flow cytometry was used to assess the levels of reactive oxygen species (ROS) and apoptosis in ccSMCs. Furthermore, a dual-luciferase reporter assay was performed to validate the relationship between miR-200a-3p and Keap1.

RESULTS

Reversal of erectile function was observed in the EVs groups, especially in the EVs-200a group. DM increased the MDA level and decreased the SOD and GSH levels. In the DM group, the expression of alpha-smooth muscle actin (α-SMA) and smooth muscle 22 alpha (SM22α) was decreased, and the expression of osteopontin (OPN) was increased. Western blotting revealed decreased Nrf2, HO-1, and Bcl2 expression and increased Keap1, Bax and cleaved caspase3 expression in the cavernous tissue. miR-200a-3p-enriched extracellular vesicles (EVs-200a) reversed these changes and inhibited the loss of smooth muscle content and cavernous fibrosis. In vitro, H2O2 induced high ROS levels in ccSMCs and increased apoptosis, and these effects reversed by EVs-200a. H2O2 reduced Nrf2, HO-1, and Bcl2 expression and increased Keap1, Bax and cleaved caspase-3 expression, and these effects were reversed by MSC-EVs, especially EVs-200a. The of dual-luciferase reporter assay results indicated that miR-200a-3p directly targeted Keap1 in a negative manner.

CONCLUSION

MSC-EVs, especially EVs-200a, alleviated erectile dysfunction in diabetic rats through the regulation of phenotypic switching, apoptosis and fibrosis. Mechanistically, miR-200a-3p targeted the Keap1/Nrf2 pathway to attenuate oxidative stress in diabetic rats.

Exosome theranostics: Comparative analysis of P body and exosome proteins and their mutations for clinical applications

Exosomes are lipid-bilayered vesicles, originating from early endosomes that capture cellular proteins and genetic materials to form multi-vesicular bodies. These exosomes are secreted into extracellular fluids such as cerebrospinal fluid, blood, urine, and cell culture supernatants. They play a key role in intercellular communication by carrying active molecules like lipids, cytokines, growth factors, metabolites, proteins, and RNAs. Recently, the potential of exosomal delivery for therapeutic purposes has been explored due to their low immunogenicity, nano-scale size, and ability to cross cellular barriers. This review comprehensively examines the biogenesis of exosomes, their isolation techniques, and their diverse applications in theranostics. We delve into the mechanisms and methods for loading exosomes with mRNA, miRNA, proteins, and drugs, highlighting their transformative role in delivering therapeutic payloads. Additionally, the utility of exosomes in stem cell therapy is discussed, showcasing their potential in regenerative medicine. Insights into exosome cargo using pre- or post-loading techniques are critical for exosome theranostics. We review exosome databases such as ExoCarta, Expedia, and ExoBCD, which document exosome cargo. From these databases, we identified 25 proteins common to both exosomes and P-bodies, known for mutations in the COSMIC database. Exosome databases do not integrate with mutation analysis programs; hence, we performed mutation analysis using additional databases. Accounting for the mutation status of parental cells and exosomal cargo is crucial in exosome theranostics. This review provides a comprehensive report on exosome databases, proteins common to exosomes and P-bodies, and their mutation analysis, along with the latest studies on exosome-engineered theranostics.

Mesenchymal stem cell secretome: A promising therapeutic strategy for erectile dysfunction?

Objective

The secretome, comprising bioactive chemicals released by mesenchymal stem cells (MSCs), holds therapeutic promise in regenerative medicine. This review aimed to explore the therapeutic potential of the MSC secretome in regenerative urology, particularly for treating erectile dysfunction (ED), and to provide an overview of preclinical and clinical research on MSCs in ED treatment and subsequently to highlight the rationales, mechanisms, preclinical investigations, and therapeutic potential of the MSC secretome in this context.

Methods

The review incorporated an analysis of preclinical and clinical research involving MSCs in the treatment of ED. Subsequently, it delved into the existing knowledge regarding the MSC secretome, exploring its therapeutic potential. The methods included a comprehensive examination of relevant literature to discern the processes underlying the therapeutic efficacy of the MSC secretome.

Results

Preclinical research indicated the effectiveness of the MSC secretome in treating various models of ED. However, the precise mechanisms of its therapeutic efficacy remain unknown. The review provided insights into the anti-inflammatory, pro-angiogenic, and trophic properties of the MSC secretome. It also discussed potential advantages, such as avoiding issues related to cellular therapy, including immunogenicity, neoplastic transformation, and cost.

Conclusion

This review underscores the significant therapeutic potential of the MSC secretome in regenerative urology, particularly for ED treatment. While preclinical studies demonstrate promising outcomes, further research is essential to elucidate the specific mechanisms underlying the therapeutic efficacy before clinical application. The review concludes by discussing future perspectives and highlighting the challenges associated with the clinical translation of the MSC secretome in regenerative urology.

Advances in the application of extracellular vesicles derived from three-dimensional culture of stem cells

Stem cells (SCs) have been used therapeutically for decades, yet their applications are limited by factors such as the risk of immune rejection and potential tumorigenicity. Extracellular vesicles (EVs), a key paracrine component of stem cell potency, overcome the drawbacks of stem cell applications as a cell-free therapeutic agent and play an important role in treating various diseases. However, EVs derived from two-dimensional (2D) planar culture of SCs have low yield and face challenges in large-scale production, which hinders the clinical translation of EVs. Three-dimensional (3D) culture, given its ability to more realistically simulate the in vivo environment, can not only expand SCs in large quantities, but also improve the yield and activity of EVs, changing the content of EVs and improving their therapeutic effects. In this review, we briefly describe the advantages of EVs and EV-related clinical applications, provide an overview of 3D cell culture, and finally focus on specific applications and future perspectives of EVs derived from 3D culture of different SCs.

BMP7-Loaded Human Umbilical Cord Mesenchymal Stem Cell-Derived Small Extracellular Vesicles Ameliorate Liver Fibrosis by Targeting Activated Hepatic Stellate Cells

Purpose

Human umbilical cord mesenchymal stem cell (hucMSC)-derived small extracellular vesicles (sEVs) are natural nanocarriers with promising potential in treating liver fibrosis and have widespread applications in the fields of nanomedicine and regenerative medicine. However, the therapeutic efficacy of natural hucMSC-sEVs is currently limited owing to their non-specific distribution in vivo and partial removal by mononuclear macrophages following systemic delivery. Thus, the therapeutic efficacy can be improved through the development of engineered hucMSC-sEVs capable to overcome these limitations.

Patients and Methods

To improve the anti-liver fibrosis efficacy of hucMSC-sEVs, we genetically engineered hucMSC-sEVs to overexpress the anti-fibrotic gene bone morphogenic protein 7 (BMP7) in parental cells. This was achieved using lentiviral transfection, following which BMP7-loaded hucMSC-sEVs were isolated through ultracentrifugation. First, the liver fibrosis was induced in C57BL/6J mice by intraperitoneal injection of 50% carbon tetrachloride (CCL4) twice a week for 8 weeks. These mice were subsequently treated with BMP7+sEVs via tail vein injection, and the anti-liver fibrosis effect of BMP7+sEVs was validated using small animal in vivo imaging, immunohistochemistry (IHC), tissue immunofluorescence, and enzyme-linked immunosorbent assay (ELISA). Finally, cell function studies were performed to confirm the in vivo results.

Results

Liver imaging and liver histopathology confirmed that the engineered hucMSC-sEVs could reach the liver of mice and aggregate around activated hepatic stellate cells (aHSCs) with a significantly stronger anti-liver fibrosis effect of BMP7-loaded hucMSC-sEVs compared to those of blank or negative control-transfected hucMSC-sEVs. In vitro, BMP7-loaded hucMSC-sEVs promoted the phenotypic reversal of aHSCs and inhibited their proliferation to enhance the anti-fibrotic effects.

Conclusion

These engineered BMP7-loaded hucMSC-sEVs offer a novel and promising strategy for the clinical treatment of liver fibrosis.

Therapeutic potential of exosome derived from hepatocyte growth factor-overexpressing adipose mesenchymal stem cells in TGFβ1-stimulated hepatic stellate cells

Cirrhosis is a familiar end-stage of multiple chronic liver diseases. The gene-modified mesenchymal stem cells (MSCs) have become one of the most promising schemes for the treatment of cirrhosis. MSCs exhibit their therapeutic role mainly by secreting hepatocyte growth factor (HGF). The aim of this research was to probe the anti-fibrosis role of exosomes secreted by HGF modified-mouse adipose MSCs (ADMSCs) on activated hepatic stellate cells (HSCs) and to preliminarily explore the possible mechanism. Firstly, mouse ADMSCs were isolated and identified. Quantitative real-time polymerase chain reaction verified the transfection efficiency of ADMSC transfected with HGF lentivirus. Exosomes derived from ADMSC transfecting negative control/HGF (ADMSCNC-Exo/ADMSCHGF-Exo) were extracted by density gradient centrifugation. HSCs were allocated to the control, TGF-β, TGF-β + ADMSC-Exo, TGF-β + ADMSCNC-Exo, and TGF-β + ADMSCHGF-Exo groups. Moreover, all mice were distributed to the control, CCl4 (40% CCl4 in olive oil), CCl4+ADMSC-Exo, CCl4+ADMSCNC-Exo, and CCl4+ADMSCHGF-Exo groups. Exosomes derived from ADMSCs with or without HGF transfection suppressed HSC activation, as evidenced by attenuating cell viability and cell cycle arrest at S phase but inducing apoptosis. Moreover, ADMSC-Exo, ADMSCNC-Exo, and ADMSCHGF-Exo effectively repressed the gene and protein levels of α-SMA, Col-I, Rho A, Cdc42, and Rac1 in TGF-β-treated HSCs, and ADMSCHGF-Exo had the best effect. ADMSCHGF-Exo had a stronger regulatory effect on serum liver index than ADMSCNC-Exo in CCl4-induced mice. In conclusion, ADMSCHGF-Exo alleviated liver fibrosis by weakening the Rho pathway, thus reducing collagen production.

Mesenchymal stem cells inhibit ferroptosis by activating the Nrf2 antioxidation pathway in severe acute pancreatitis-associated acute lung injury

Severe acute pancreatitis-associated acute lung injury (SAP-ALI) remains a significant challenge for healthcare practitioners because of its high morbidity and mortality; therefore, there is an urgent need for an effective treatment. Mesenchymal stem cells (MSCs) have shown significant potential in the treatment of a variety of refractory diseases, including lung diseases. This study aimed to investigate the protective effects of MSCs against SAP-ALI and its underlying mechanisms. Our results suggest that MSCs mitigate pathological injury, hemorrhage, edema, inflammatory response in lung tissue, and lipopolysaccharide (LPS)-induced cell damage in RLE-6TN cells (a rat alveolar epithelial cell line). The results also showed that MSCs, similar to the effects of ferrostatin-1 (ferroptosis inhibitor), suppressed the ferroptosis response, which was manifested as down-regulated Fe2+, malondialdehyde, and reactive oxygen species (ROS) levels, and up-regulated glutathione peroxidase 4 (GPX4) and glutathione (GSH) levels in vivo and in vitro. The activation of ferroptosis by erastin (a ferroptosis agonist) reversed the protective effect of MSCs against SAP-ALI. Furthermore, MSCs activated the nuclear factor erythroid 2 associated factor 2 (Nrf2) transcription factor, and blocking the Nrf2 signaling pathway with ML385 abolished the inhibitory effect of MSCs on ferroptosis in vitro. Collectively, these results suggest that MSCs have therapeutic effects against SAP-ALI. The specific mechanism involves inhibition of ferroptosis by activating the Nrf2 transcription factor.

Application of dental pulp stem cells for bone regeneration

Bone defects resulting from severe trauma, tumors, inflammation, and other factors are increasingly prevalent. Stem cell-based therapies have emerged as a promising alternative. Dental pulp stem cells (DPSCs), sourced from dental pulp, have garnered significant attention owing to their ready accessibility and minimal collection-associated risks. Ongoing investigations into DPSCs have revealed their potential to undergo osteogenic differentiation and their capacity to secrete a diverse array of ontogenetic components, such as extracellular vesicles and cell lysates. This comprehensive review article aims to provide an in-depth analysis of DPSCs and their secretory components, emphasizing extraction techniques and utilization while elucidating the intricate mechanisms governing bone regeneration. Furthermore, we explore the merits and demerits of cell and cell-free therapeutic modalities, as well as discuss the potential prospects, opportunities, and inherent challenges associated with DPSC therapy and cell-free therapies in the context of bone regeneration.

Ultrasonic microbubbles promote mesenchymal stem cell homing to the fibrotic liver via upregulation of CXCR4 expression

OBJECTIVE

To investigate the mechanism of ultrasound microbubbles (UTMB) promoting stem cells homing to fibrotic liver.

METHODS

Bone marrow derived mesenchymal stem cells (BMSCs) were divided into 5 groups with or without ultrasound microbubbles and continuously irradiated with ultrasound conditions of frequency 1 MHZ and output power 0.6 W/cm2 for different times, and then injected into a mouse model of liver fibrosis through the tail vein with or without ultrasound microbubbles, with sound intensity. The effect of ultrasound microbubbles on MSC expression of CXC chemokine receptor 4 (CXCR4) and homing fibrotic liver was evaluated by flow cytometry (FCM), western blot (WB) and immunohistochemistry (IHC) analysis.

RESULTS

The level of CXCR4 expression was significantly higher in the ultrasound microbubble group than in the non-intervention group (P < 0.05), and the number of MSC and the rate of CXCR4 receptor positivity in the ultrasound microbubble-treated liver tissues were significantly higher than in the non-intervention group (P < 0.01).

CONCLUSION

Ultrasonic microbubbles can promote the expression of CXCR4 on the surface of MSCs, thus improving the homing rate of MSCs in fibrotic liver.

Human umbilical cord-derived mesenchymal stem cells ameliorate liver fibrosis by improving mitochondrial function via Slc25a47-Sirt3 signaling pathway

Chronic Liver fibrosis may progress to liver cirrhosis and hepatocellular carcinoma (HCC), hence cause a substantial global burden. However, effective therapies for blocking fibrosis are still lacking. Although mesenchymal stem cells (MSCs) have been proven beneficial to liver regeneration after damage, the underlying mechanism of their therapeutic effects are not fully understood. Oxidative stress and mitochondrial functionality alteration directly contributes to the hepatocyte apoptosis and development of liver fibrosis. This study aims to elucidate the mechanism by which hUC-MSC alleviates liver fibrosis and mitochondrial dysfunction. RNA-sequencing was performed to characterize the transcriptomic changes after implantation of hUC-MSCs in mice with liver fibrosis. Next, western blot, RT-PCR, immunohistochemical and immunofluorescence staining were used to evaluate the expression of different genes in vitro and in vivo. Additionally, mitochondrial morphological and dynamic changes, ROS content, and ATP production were examined. Slc25a47, a newly identified liver-specific mitochondrial NAD+ transporter, was notably reduced in CCl4-treated mice and H2O2-stimulated hepatocytes. Conversely, hUC-MSCs increased the Slc25a47 expression and NAD+ level within mitochondria, thereby enhanced Sirt3 protein activity and alleviated mitochondrial dysfunction in the liver. Furthermore, Slc25a47 knockdown could partially abrogate the protective effects of hUC-MSCs on H2O2-induced mitochondrial fission and oxidative stress in hepatocytes. Our study illustrates that Slc25a47 is a key molecular for hUC-MSCs to improve liver fibrosis and regulates mitochondrial function through Sirt3 for the first time, and providing a theoretical basis for the clinical translation of hUC-MSCs transplantation in the treatment of patients with liver fibrosis/cirrhosis.

The Role of Induced Pluripotent Stem Cells in the Treatment of Stroke

Stroke is a neurological disorder with high disability and mortality rates. Almost 80% of stroke cases are ischemic stroke, and the remaining are hemorrhagic stroke. The only approved treatment for ischemic stroke is thrombolysis and/or thrombectomy. However, these treatments cannot sufficiently relieve the disease outcome, and many patients remain disabled even after effective thrombolysis. Therefore, rehabilitative therapies are necessary to induce remodeling in the brain. Currently, stem cell transplantation, especially via the use of induced pluripotent stem cells (iPSCs), is considered a promising alternative therapy for stimulating neurogenesis and brain remodeling. iPSCs are generated from somatic cells by specific transcription factors. The biological functions of iPSCs are similar to those of embryonic stem cells (ESCs), including immunomodulation, reduced cerebral blood flow, cerebral edema, and autophagy. Although iPSC therapy plays a promising role in both hemorrhagic and ischemic stroke, its application is associated with certain limitations. Tumor formation, immune rejection, stem cell survival, and migration are some concerns associated with stem cell therapy. Therefore, cell-free therapy as an alternative method can overcome these limitations. This study reviews the therapeutic application of iPSCs in stroke models and the underlying mechanisms and constraints of these cells. Moreover, cell-free therapy using exosomes, apoptotic bodies, and microvesicles as alternative treatments is discussed.

Multifaceted Characterization of Human Embryonic Stem Cell-Derived Mesenchymal Stem/Stromal Cells Revealed Amelioration of Acute Liver Injury in NOD-SCID Mice

Human embryonic stem cells (hESCs) are advantaged sources for large-scale and homogeneous mesenchymal stem/stromal cells (MSCs) generation. However, due to the limitations in high-efficiency procedures for hESC-MSCs induction, the systematic and detailed information of mesengenesis and early MSC development are largely obscure. In this study, we took advantage of the well-established twist-related protein 1 (TWIST1)-overexpressing hESCs and two small molecular cocktails (CHIR99021, decitabine) for high-efficient MSC induction. To assess the multidimensional biological and transcriptomic characteristics, we turned to cellular and molecular methods, such as flow cytometry (FCM), quantitative reverse transcription-polymerase chain reaction (qRT-PCR), in vitro tri-lineage differentiation, cytokine secretion analysis, in vivo transplantation for acute liver injury (ALI) management, and bioinformatics analyses (eg, gene ontology-biological processes [GO-BP], Kyoto Encyclopedia of Genes and Genomes [KEGG], HeatMap, and principal component analysis [PCA]). By combining TWIST1 overexpression (denoted as T) and the indicated small molecular cocktails (denoted as S), hESCs high-efficiently differentiated into MSCs (denoted as TS-MSCs, induced by T and S combination) within 2 weeks. TS-MSCs satisfied the criteria for MSC definition and revealed comparable tri-lineage differentiation potential and ameliorative efficacy upon ALI mice. According to RNA-sequencing (SEQ) analysis, we originally illuminated the gradual variations in gene expression pattern and the concomitant biofunctions of the programmed hESC-MSCs. Overall, our data indicated the feasibility of high-efficient generation of hESC-MSCs by TWIST1 and cocktail-based programming. The generated hESC-MSCs revealed multifaceted in vivo and in vitro biofunctions as adult BM-MSCs, which collectively suggested promising prospects in ALI management in future.

Nanoghosts: Harnessing Mesenchymal Stem Cell Membrane for Construction of Drug Delivery Platforms Via Optimized Biomimetics

Mesenchymal stem cells (MSCs) are becoming hotspots for application in disease therapies recently, combining with biomaterials and drug delivery system. A major advantage of MSCs applied in drug delivery system is that these cells enable specific targeting and releasing of cargos to the disease sites. However, the potential tumor tropic effects of MSCs raised concerns on biosafety. To solve this problem, there are emerging methods of isolating cell membranes and developing nanoformulations to perform drug delivery, which avoids concerns on biosafety without disturbing the membrane functions of specific polarizing and locating. These cargoes are so called "nanoghosts." This review article summarizes the current applications of nanoghosts, the promising potential of MSCs to be applied in membrane isolation and nanoghost construction, and possible approaches to develop better drug delivery system harnessing from MSC ghost cell membranes.

Therapeutic potential of stem cells in regeneration of liver in chronic liver diseases: Current perspectives and future challenges

The deposition of extracellular matrix and hyperplasia of connective tissue characterizes chronic liver disease called hepatic fibrosis. Progression of hepatic fibrosis may lead to hepatocellular carcinoma. At this stage, only liver transplantation is a viable option. However, the number of possible liver donors is less than the number of patients needing transplantation. Consequently, alternative cell therapies based on non-stem cells (e.g., fibroblasts, chondrocytes, keratinocytes, and hepatocytes) therapy may be able to postpone hepatic disease, but they are often ineffective. Thus, novel stem cell-based therapeutics might be potentially important cutting-edge approaches for treating liver diseases and reducing patient' suffering. Several signaling pathways provide targets for stem cell interventions. These include pathways such as TGF-β, STAT3/BCL-2, NADPH oxidase, Raf/MEK/ERK, Notch, and Wnt/β-catenin. Moreover, mesenchymal stem cells (MSCs) stimulate interleukin (IL)-10, which inhibits T-cells and converts M1 macrophages into M2 macrophages, producing an anti-inflammatory environment. Furthermore, it inhibits the action of CD4+ and CD8+ T cells and reduces the activity of TNF-α and interferon cytokines by enhancing IL-4 synthesis. Consequently, the immunomodulatory and anti-inflammatory capabilities of MSCs make them an attractive therapeutic approach. Importantly, MSCs can inhibit the activation of hepatic stellate cells, causing their apoptosis and subsequent promotion of hepatocyte proliferation, thereby replacing dead hepatocytes and reducing liver fibrosis. This review discusses the multidimensional therapeutic role of stem cells as cell-based therapeutics in liver fibrosis.

Stem Cell Therapy for Liver Diseases: Current Perspectives

Stem cell therapy offers a promising avenue for advanced liver disease cases as an alternative to liver transplantation. Clinical studies are underway to explore the potential of stem cells from various sources in treating different liver diseases. However, due to the variability among current studies, further validation is needed to ensure the safety and effectiveness of stem cell therapy. To establish a strong foundation for optimal stem cell therapy applications, selection of suitable stem cell sources, standardization of transplantation protocols, and patient criteria are vital. This review comprehensively examines existing literature on stem cell sources, transplantation methods, and patient selection. Additionally, we discuss novel strategies, including stem cell preconditioning, cell-free therapy, genetic modification of stem cells, and the use of liver organoids, addressing the limitations of current stem cell therapies. Nevertheless, these innovative approaches require further validation.

Strategies to improve the therapeutic efficacy of mesenchymal stem cell-derived extracellular vesicle (MSC-EV): a promising cell-free therapy for liver disease

Liver disease has emerged as a significant worldwide health challenge due to its diverse causative factors and therapeutic complexities. The majority of liver diseases ultimately progress to end-stage liver disease and liver transplantation remains the only effective therapy with the limitations of donor organ shortage, lifelong immunosuppressants and expensive treatment costs. Numerous pre-clinical studies have revealed that extracellular vesicles released by mesenchymal stem cells (MSC-EV) exhibited considerable potential in treating liver diseases. Although natural MSC-EV has many potential advantages, some characteristics of MSC-EV, such as heterogeneity, uneven therapeutic effect, and rapid clearance in vivo constrain its clinical translation. In recent years, researchers have explored plenty of ways to improve the therapeutic efficacy and rotation rate of MSC-EV in the treatment of liver disease. In this review, we summarized current strategies to enhance the therapeutic potency of MSC-EV, mainly including optimization culture conditions in MSC or modifications of MSC-EV, aiming to facilitate the development and clinical application of MSC-EV in treating liver disease.

Intranasal delivery of stem cells labeled by nanoparticles in neurodegenerative disorders: Challenges and opportunities

Neurodegenerative disorders occur through progressive loss of function or structure of neurons, with loss of sensation and cognition values. The lack of successful therapeutic approaches to solve neurologic disorders causes physical disability and paralysis and has a significant socioeconomic impact on patients. In recent years, nanocarriers and stem cells have attracted tremendous attention as a reliable approach to treating neurodegenerative disorders. In this regard, nanoparticle-based labeling combined with imaging technologies has enabled researchers to survey transplanted stem cells and fully understand their fate by monitoring their survival, migration, and differentiation. For the practical implementation of stem cell therapies in the clinical setting, it is necessary to accurately label and follow stem cells after administration. Several approaches to labeling and tracking stem cells using nanotechnology have been proposed as potential treatment strategies for neurological diseases. Considering the limitations of intravenous or direct stem cell administration, intranasal delivery of nanoparticle-labeled stem cells in neurological disorders is a new method of delivering stem cells to the central nervous system (CNS). This review describes the challenges and limitations of stem cell-based nanotechnology methods for labeling/tracking, intranasal delivery of cells, and cell fate regulation as theragnostic labeling. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease.

Potential of mesenchymal stem cell-derived conditioned medium/secretome as a therapeutic option for ocular diseases

Research has shown that the therapeutic effect of mesenchymal stem cells (MSCs) is partially due to its secreted factors as opposed to the implantation of the cells into the treated tissue or tissue replacement. MSC secretome, especially in the form of conditioned medium (MSC-CM) is now being explored as an alternative to MSCs transplantation. Despite the observed benefits of MSC-CM, only a few clinical trials have evaluated it and other secretome components in the treatment of eye diseases. This review provides insight into the potential therapeutic use of MSC-CM in eye conditions, such as corneal diseases, dry eye, glaucoma, retinal diseases and uveitis. We discuss the current evidence, some limitations, and the progress that remains to be achieved before clinical translation becomes possible.

Mesenchymal Stem Cell Therapy in Acute Liver Failure

Acute liver failure (ALF) is a severe liver disease syndrome with rapid deterioration and high mortality. Liver transplantation is the most effective treatment, but the lack of donor livers and the high cost of transplantation limit its broad application. In recent years, there has been no breakthrough in the treatment of ALF, and the application of stem cells in the treatment of ALF is a crucial research field. Mesenchymal stem cells (MSCs) are widely used in disease treatment research due to their abundant sources, low immunogenicity, and no ethical restrictions. Although MSCs are effective for treating ALF, the application of MSCs to ALF needs to be further studied and optimized. In this review, we discuss the potential mechanisms of MSCs therapy for ALF, summarize some methods to enhance the efficacy of MSCs, and explore optimal approaches for MSC transplantation.

Immunomodulatory potential of human clonal mesenchymal stem cells and their extracellular vesicle subpopulations in an inflammatory-mediated diabetic Rhesus monkey model

AIMS

This study aimed to investigate the therapeutic potential of a homogenous clonal population of mesenchymal stem cells (cMSC) and their extracellular vesicles (cMSC-EV) subpopulations on isolated rat islets in vitro and in inflammatory-mediated type 1 diabetes (T1D) non-human primate models.

MAIN METHODS

EV subpopulations were isolated from human bone marrow-derived cMSC supernatant by low- and high-speed ultracentrifuge (EV-20K and EV-U110K) and sucrose density gradient (EV-S110K). The EVs were characterized generally and for the level of albumin, acetylcholinesterase (AChE) activity, co-isolate apoptotic markers, and expression of CD63+/annexin V+. Rat islet-derived single cells (iSCs) proliferation was measured using a Ki-67 proliferation assay. Diabetes was induced by multiple low-dose administrations of streptozotocin in rhesus monkeys. The diabetic monkeys were divided into three groups: the cMSC group, received two injections of 1.5 × 106 cMSC/kg body weight; the EV group received two injections of EVs isolated from 1.5 × 106 cMSC/kg, and the vehicle group received phosphate-buffered saline.

KEY FINDINGS

EV-S110K showed higher AChE activity, lower expression of CD63+/annexin V+, and lower apoptotic co-isolates. EV-S110K induced β-cell proliferation in vitro in a dose-dependent manner. The administration of EV-S110K and/or cMSC in diabetic monkeys demonstrated no significant changes in general diabetic indices and β-cell mass in the pancreas of the monkeys. Both treatments demonstrated a lowering trend in blood glucose levels and reduced pro-inflammatory cytokines. In contrast, regulatory T cells and anti-inflammatory cytokines were increased.

SIGNIFICANCE

cMSC and cMSC-EV provided initial evidence to attenuate clinical symptoms in inflammatory-mediated T1D non-human primates through immunomodulation.

The Immunomodulatory Role of Cell-Free Approaches in SARS-CoV-2-Induced Cytokine Storm-A Powerful Therapeutic Tool for COVID-19 Patients

Currently, there is still no effective and definitive cure for the coronavirus disease 2019 (COVID-19) caused by the infection of the novel highly contagious severe acute respiratory syndrome virus (SARS-CoV-2), whose sudden outbreak was recorded for the first time in China in late December 2019. Soon after, COVID-19 affected not only the vast majority of China's population but the whole world and caused a global health public crisis as a new pandemic. It is well known that viral infection can cause acute respiratory distress syndrome (ARDS) and, in severe cases, can even be lethal. Behind the inflammatory process lies the so-called cytokine storm (CS), which activates various inflammatory cytokines that damage numerous organ tissues. Since the first outbreak of SARS-CoV-2, various research groups have been intensively trying to investigate the best treatment options; however, only limited outcomes have been achieved. One of the most promising strategies represents using either stem cells, such as mesenchymal stem cells (MSCs)/induced pluripotent stem cells (iPSCs), or, more recently, using cell-free approaches involving conditioned media (CMs) and their content, such as extracellular vesicles (EVs) (e.g., exosomes or miRNAs) derived from stem cells. As key mediators of intracellular communication, exosomes carry a cocktail of different molecules with anti-inflammatory effects and immunomodulatory capacity. Our comprehensive review outlines the complex inflammatory process responsible for the CS, summarizes the present results of cell-free-based pre-clinical and clinical studies for COVID-19 treatment, and discusses their future perspectives for therapeutic applications.

Role of adipocyte-derived extracellular vesicles during the progression of liver inflammation to hepatocellular carcinoma

Extracellular vesicles are membrane-bound cargos that vary in size and are stably transported through various bodily fluids. Extracellular vesicles communicate information between the cells and organs. Extracellular vesicles from the diseased cells alter cellular responses of the recipient cells contributing to disease progression. In obesity, adipocytes become hypertrophic and the extracellular vesicles from these dysfunctional adipocytes showed altered cargo contents instigating pathophysiological response leading to chronic liver diseases. In this review, the role of adipocyte-derived extracellular vesicles on the progression of liver inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma are extensively discussed. Newer approaches are crucial to take advantage of extracellular vesicles and their content as biomarkers to diagnose initial liver inflammation before reaching to an irreversible liver failure stage.

Magnetic Nanostructures and Stem Cells for Regenerative Medicine, Application in Liver Diseases

The term "liver disease" refers to any hepatic condition that leads to tissue damage or altered hepatic function and can be induced by virus infections, autoimmunity, inherited genetic mutations, high consumption of alcohol or drugs, fat accumulation, and cancer. Some types of liver diseases are becoming more frequent worldwide. This can be related to increasing rates of obesity in developed countries, diet changes, higher alcohol intake, and even the coronavirus disease 2019 (COVID-19) pandemic was associated with increased liver disease-related deaths. Although the liver can regenerate, in cases of chronic damage or extensive fibrosis, the recovery of tissue mass is impossible, and a liver transplant is indicated. Because of reduced organ availability, it is necessary to search for alternative bioengineered solutions aiming for a cure or increased life expectancy while a transplant is not possible. Therefore, several groups were studying the possibility of stem cells transplantation as a therapeutic alternative since it is a promising strategy in regenerative medicine for treating various diseases. At the same time, nanotechnological advances can contribute to specifically targeting transplanted cells to injured sites using magnetic nanoparticles. In this review, we summarize multiple magnetic nanostructure-based strategies that are promising for treating liver diseases.

Cell therapy in end-stage liver disease: replace and remodel

Liver disease is prevalent worldwide. When it reaches the end stage, mortality rises to 50% or more. Although liver transplantation has emerged as the most efficient treatment for end-stage liver disease, its application has been limited by the scarcity of donor livers. The lack of acceptable donor organs implies that patients are at high risk while waiting for suitable livers. In this scenario, cell therapy has emerged as a promising treatment approach. Most of the time, transplanted cells can replace host hepatocytes and remodel the hepatic microenvironment. For instance, hepatocytes derived from donor livers or stem cells colonize and proliferate in the liver, can replace host hepatocytes, and restore liver function. Other cellular therapy candidates, such as macrophages and mesenchymal stem cells, can remodel the hepatic microenvironment, thereby repairing the damaged liver. In recent years, cell therapy has transitioned from animal research to early human studies. In this review, we will discuss cell therapy in end-stage liver disease treatment, especially focusing on various cell types utilized for cell transplantation, and elucidate the processes involved. Furthermore, we will also summarize the practical obstacles of cell therapy and offer potential solutions.

Comparison of therapeutic effects of mesenchymal stem cells derived from superficial and deep subcutaneous adipose tissues

BACKGROUND

Fibrosis is a common histological feature in the process from chronic organ injury to organ failure. Chronic tissue injury causes inflammatory cell infiltration into the injured tissue. The persistence of this inflammatory cell infiltration leads to fibrosis and organ failure. Adipose-derived mesenchymal stem cells (ASCs) have received much attention as a regenerative therapeutic tool to prevent progression from organ injury to failure. Subcutaneous abdominal adipose tissue is divided into superficial and deep layers by a superficial fascia. Adipose tissue easily collected by liposuction is usually obtained from a deep layer, so ASCs derived from a deep layer are generally used for regenerative medicine. However, no research has been conducted to investigate differences in the therapeutic effects of ASCs from the superficial and deep layers (Sup-ASCs and Deep-ASCs, respectively). Therefore, we compared the therapeutic potencies of Sup-ASCs and Deep-ASCs.

METHODS

ASCs were isolated from superficial and deep subcutaneous abdominal adipose tissues collected from patients who underwent breast reconstruction. We first compared cell characteristics, such as morphology, cell proliferation, cell surface markers, adipogenic and osteogenic differentiation, cell senescence markers, and expression of coagulation and anticoagulant factors between Sup-ASCs and Deep-ASCs. Furthermore, we compared their ability to promote polarization of M2 macrophages and to inhibit transforming growth factor (TGF)-β/Smad signaling using THP-1 cells and TGF-β1 stimulated HK-2 cells incubated with conditioned media from Sup-ASCs or Deep-ASCs. In in vivo experiments, after renal ischemia-reperfusion injury (IRI) procedure, Sup-ASCs or Deep-ASCs were injected through the abdominal aorta. At 21 days post-injection, the rats were sacrificed and their left kidneys were collected to evaluate fibrosis. Finally, we performed RNA-sequencing analysis of Sup-ASCs and Deep-ASCs.

RESULTS

Sup-ASCs had greater proliferation and adipogenic differentiation compared with Deep-ASCs, whereas both ASC types had similar morphology, cell surface markers, senescence markers, and expression of coagulation and anticoagulant factors. Conditioned media from Sup-ASCs and Deep-ASCs equally promoted polarization of M2 macrophages and suppressed TGF-β/Smad signaling. Moreover, administration of Sup-ASCs and Deep-ASCs equally ameliorated renal fibrosis induced by IRI in rats. RNA-sequencing analysis revealed no significant difference in the expression of genes involved in anti-inflammatory and anti-fibrotic effects between Sup-ASCs and Deep-ASCs.

CONCLUSIONS

These results indicate that both Sup-ASCs and Deep-ASCs can be used effectively and safely as an intravascular ASC therapy for organ injury.

Exosomes from adipose-derived mesenchymal stem cells can attenuate liver injury caused by minimally invasive hemihepatectomy combined with ischemia-reperfusion in minipigs by modulating the endoplasmic reticulum stress response

AIMS

Hepatic ischemia-reperfusion injury (IRI) impairs postoperative recovery of liver function after liver resection or transplantation. It is crucial to minimize liver injury during surgery in order to improve patient survival and quality of life. The aim of this study was to explore the therapeutic efficacy of exosomes from adipose-derived mesenchymal stem cells (ADSCs-exo) against hepatectomy combined with IRI injury and compare that with the effect of adipose-derived mesenchymal stem cells (ADSCs).

MAIN METHOD

Minimally invasive hemihepatectomy combined with hepatic IRI was established in minipigs. A single dose of ADSCs-exo, ADSCs or PBS was injected through the portal vein. The histopathological features and function of the liver, and the oxidative stress levels, endoplasmic reticulum (ER) ultrastructure and ER stress (ERS) response were analyzed pre- and postoperatively.

KEY FINDINGS

ADSCs-exo alleviated the histopathological injuries and ultrastructural changes in the ER, and significantly improved ALP, TP and CAT levels. Furthermore, ADSCs-exo treatment also downregulated ERS-related factors such as GRP78, ATF6, IRE1α/XBP1, PERK/eIF2α/ATF4, JNK and CHOP. The therapeutic effects of ADSCs-exo and ADSCs were similar.

SIGNIFICANCE

Intravenous administration of a single dose of ADSCs-exo is a novel cell-free therapeutic approach to improve surgery-related liver injury. Our findings provide evidence of the paracrine effect of ADSCs and an experimental basis for treating liver injury with ADSCs-exo instead of ADSCs.

Herpetin Promotes Bone Marrow Mesenchymal Stem Cells to Alleviate Carbon Tetrachloride-Induced Acute Liver Injury in Mice

Herpetin, an active compound derived from the seeds of Herpetospermum caudigerum Wall., is a traditional Tibetan herbal medicine that is used for the treatment of hepatobiliary diseases. The aim of this study was to evaluate the stimulant effect of herpetin on bone marrow mesenchymal stem cells (BMSCs) to improve acute liver injury (ALI). In vitro results showed that herpetin treatment enhanced expression of the liver-specific proteins alpha-fetoprotein, albumin, and cytokeratin 18; increased cytochrome P450 family 3 subfamily a member 4 activity; and increased the glycogen-storage capacity of BMSCs. Mice with ALI induced by carbon tetrachloride (CCl₄) were treated with a combination of BMSCs by tail-vein injection and herpetin by intraperitoneal injection. Hematoxylin and eosin staining and serum biochemical index detection showed that the liver function of ALI mice improved after administration of herpetin combined with BMSCs. Western blotting results suggested that the stromal cell-derived factor-1/C-X-C motif chemokine receptor 4 axis and the Wnt/β-catenin pathway in the liver tissue were activated after treatment with herpetin and BMSCs. Therefore, herpetin is a promising BMSC induction agent, and coadministration of herpetin and BMSCs may affect the treatment of ALI.

Multipotent Mesenchymal Stem Cell-Based Therapies for Spinal Cord Injury: Current Progress and Future Prospects

Spinal cord injury (SCI) represents a significant medical challenge, often resulting in permanent disability and severely impacting the quality of life for affected individuals. Traditional treatment options remain limited, underscoring the need for novel therapeutic approaches. In recent years, multipotent mesenchymal stem cells (MSCs) have emerged as a promising candidate for SCI treatment due to their multifaceted regenerative capabilities. This comprehensive review synthesizes the current understanding of the molecular mechanisms underlying MSC-mediated tissue repair in SCI. Key mechanisms discussed include neuroprotection through the secretion of growth factors and cytokines, promotion of neuronal regeneration via MSC differentiation into neural cell types, angiogenesis through the release of pro-angiogenic factors, immunomodulation by modulating immune cell activity, axonal regeneration driven by neurotrophic factors, and glial scar reduction via modulation of extracellular matrix components. Additionally, the review examines the various clinical applications of MSCs in SCI treatment, such as direct cell transplantation into the injured spinal cord, tissue engineering using biomaterial scaffolds that support MSC survival and integration, and innovative cell-based therapies like MSC-derived exosomes, which possess regenerative and neuroprotective properties. As the field progresses, it is crucial to address the challenges associated with MSC-based therapies, including determining optimal sources, intervention timing, and delivery methods, as well as developing standardized protocols for MSC isolation, expansion, and characterization. Overcoming these challenges will facilitate the translation of preclinical findings into clinical practice, providing new hope and improved treatment options for individuals living with the devastating consequences of SCI.

Protective effects of human amniotic membrane derived mesenchymal stem cells (hAMSCs) secreted factors on mouse spermatogenesis and sperm chromatin condensation following unilateral testicular torsion

Testicular torsion is considered a urological disorder that requires immediate detorsion surgery. Ischemia/reperfusion (I/R) injury after testicular torsion detorsion causes of drastic impairment of spermatogenesis and infertility. Cell-free-based approaches seem to be a promising strategy to prevent I/R injury, they have more stable biological properties, and they contain paracrine factors of mesenchymal stem cells. The purpose of this study was to evaluate the protective effects of human amniotic membrane derived mesenchymal stem cells (hAMSCs) secreted factors on mouse sperm chromatin condensation and spermatogenesis improvement after I/R injury. hAMSCs were isolated and characterized by RT- PCR and flow cytometry, preparation of hAMSCs secreted factors was performed. Forty male mice were randomly divided into 4 groups: sham-operated, torsion detorsion, torsion detorsion+ intratesticular injection of DMEM/F-12, and torsion detorsion+ intratesticular injection of hAMSCs secreted factors. After one cycle of spermatogenesis, the mean number of germ cells, Sertoli, Leydig, myoid as well as tubular parameters, Johnson score, and spermatogenesis indexes were evaluated by H& E and PAS stainings. Sperm chromatin condensation and relative expression of c-kit and prm 1 genes were assessed by aniline blue staining and real-time PCR, respectively. The mean number of spermatogenic cells, Leydig, Myoid, Sertoli, spermatogenesis parameters, Johnson score, as well as germinal epithelial height and diameters of seminiferous tubules decreased significantly after I/R injury. The thickness of basement membrane and percentage of sperm with excessive histone significantly increased, while the relative expression of c-kit and prm 1 significantly decreased in torsion detorsion group (p<0.001). hAMSCs secreted factors remarkably restored normal sperm chromatin condensation, spermatogenesis parameters and histomorphometric organization of seminiferous tubules via intratesticular injection (p<0.001). Thus, hAMSCs secreted factors may potentially salvage torsion-detorsion-induced infertility.

The effect of mesenchymal stem cell-derived supernatant nasal administration on lung inflammation and immune response in BCG-vaccinated BALB/c mice

Mesenchymal stem cells (MSCs) are among the known cells that can control and modulate immune responses in different circumstances, including autoimmune diseases. Also, various studies have shown that they can prevent and reduces the pulmonary inflammation caused by infectious agents. In the case of tuberculosis and inflammation caused by BCG, the granuloma has destructive effects and improper orientation of the immune response. Therefore, it is possible to prevent airway damage by preventing harmful inflammatory responses and guiding the immune system responses. This study investigates the role of nasal administration of MSCs supernatant by designing an inflammatory model in the BALB/c mice lung with BCG. MSCs are isolated from mice adipose tissue in this study and evaluated for their phenotypic and differentiation properties. After the third passage, these cells' condition medium (CM) was collected. 20 mice were divided into four groups. Group 1 receive BCG (10⁷ CFU in 5 ml volume for 15 min) nasal administration. Group 2 treated with CM, and group 3 initially were treated with CM (in 5 ml volume for 15 min) and, after 24 h, treated with BCG nasal administration. CM treatment was continued every five days for one month. The fourth group of mice was treated with PBS nasal administration of CM and BCG. One week after the last administration, the lung tissue of mice in each group was pathologically examined. In addition, secretion of IL1-β, IL-6, TNF-α, TGF-β, and IL-10 in the alveolar fluid and secretion of IL-4 and IFN-γ cytokines in the supernatant of splenocytes was evaluated by ELISA. The TNF-α/IL-10 ratio in the alveolar lung fluid of the BCG received group is 2/9 and decreased to 0.58 after successive CM treatment. Therefore, it can be concluded that inflammatory responses to BCG infection in the presence of CM are balanced and pave the way for the induction of effective immune responses by reducing lung tissue damage.

What Do NAFLD, Liver Fibrosis, and Inflammatory Bowel Disease Have in Common? Review of the Current Literature

Liver disease is one of the most common extraintestinal manifestations of inflammatory bowel disease (IBD). Often the course of liver disease is associated with an exacerbation of the underlying disease (Crohn’s Disease/Ulcerative Colitis). Nonalcoholic steatohepatitis encompasses a wide spectrum of liver damage. The most common form is nonalcoholic fatty liver disease (NAFLD) (75–80%), and the less common but more dangerous form is nonalcoholic steatohepatitis (NASH). NAFLD is now the most common cause of chronic liver disease in developed countries and the leading indication for liver transplantation in the United States. Genetic, demographic, clinical, and environmental factors can play a role in the pathogenesis of NAFLD. The increasing prevalence of NAFLD is associated with a widespread obesity epidemic, metabolic complications, including hypertension, type 2 diabetes, and dyslipidaemia. Some of the most common manifestations of IBD are liver, biliary tract, and gallbladder diseases. The liver fibrosis process has a complex pathophysiology and is often dependent on exogenous factors such as the treatment used and endogenous factors such as the gut microbiome. However, the factors that link IBD and liver fibrosis are not yet clear. The main purpose of the review is to try to find links between IBD and selected liver diseases and to identify knowledge gaps that will inform further research.

Human umbilical cord blood mesenchymal stem cells as a potential therapy for schistosomal hepatic fibrosis: an experimental study

The objective of our study was to assess the effect of human umbilical cord blood (HUCB) mesenchymal stem cells (MSCs) transplantation on schistosomal hepatic fibrosis in mice. The study animals were divided into three groups. Group I is a control group, where the mice were infected with Schistosoma mansoni cercariae and remained untreated. The mice of the other two groups were infected and treated with either praziquantel (Group II) or HUCB-MSCs (Group III). Liver function tests, as well as histopathological evaluation of liver fibrosis using hematoxylin and eosin and Masson's trichrome stains, were performed. Additionally, an immunohistochemical study was carried out using anti-glial fibrillary acidic protein (GFAP) in hepatic stellate cells. Compared to the control group, the treated (praziquantel and MSCs) groups showed a substantial improvement, with a significant difference regarding the histopathological evaluation of liver fibrosis in the MSCs-treated group. In conclusion, MSCs could be a promising and efficient cell therapy for liver fibrosis.

Exosomes and Nano-SDF Scaffold as a Cell-Free-Based Treatment Strategy Improve Traumatic Brain Injury Mechanisms by Decreasing Oxidative Stress, Neuroinflammation, and Increasing Neurogenesis

Traumatic brain injury (TBI) causes a variety of complex pathological changes in brain parenchymal tissue by increasing neuroinflammatory and apoptosis responses. Currently, there is no treatment to resolve the consequences related to TBI. Recently, an extensive literature has grown up around the theme of bystander effects of stem cells, a mechanism of stem cells without the need for cell transplantation, which is called cell-free therapy. The purpose of this investigation was to determine the efficacy of a cell-free-based therapy strategy using exosomes derived from human neural stem cells (hNSCs) and a novel nano-scaffold in rats subjected to TBI. In this study, a series of in vitro and in vivo experiments from behavior tests to gene expression was performed to define the effect of exosomes in combination with a three-dimensional (3D) nano-scaffold containing a bio-motif of SDF1α (Nano-SDF). Application of exosomes with Nano-SDF significantly decreased oxidative stress in serum and brain samples. Moreover, treatment with exosomes and Nano-SDF significantly reduced the expression of Toll-like receptor 4 and its downstream signaling pathway, including NF-kβ and interleukin-1β. We also found that the cell-free-based therapy strategy could decrease reactive gliosis at the injury site. Interestingly, we showed that exosomes with Nano-SDF increased neurogenesis in the sub-ventricular zone of the lateral ventricle, indicating a bio-bridge mechanism. To sum up, the most obvious finding to emerge from this study is that a cell-free-based therapy strategy can be an effective option for future practice in the course of TBI.

Immunomodulatory role of mesenchymal stem cell therapy in liver fibrosis

Liver fibrosis is a fibrogenic and inflammatory process that results from hepatocyte injury and is characterized by hepatic architectural distortion and resultant loss of liver function. There is no effective treatment for advanced fibrosis other than liver transplantation, but it is limited by expensive costs, immune rejection, and postoperative complications. With the development of regenerative medicine in recent years, mesenchymal stem cell (MSCs) transplantation has become the most promising treatment for liver fibrosis. The underlying mechanisms of MSC anti-fibrotic effects include hepatocyte differentiation, paracrine, and immunomodulation, with immunomodulation playing a central role. This review discusses the immune cells involved in liver fibrosis, the immunomodulatory properties of MSCs, and the immunomodulation mechanisms of MSC-based strategies to attenuate liver fibrosis. Meanwhile, we discuss the current challenges and future directions as well.

Application of Biocompatible Scaffolds in Stem-Cell-Based Dental Tissue Engineering

Tissue engineering as an important field in regenerative medicine is a promising therapeutic approach to replace or regenerate injured tissues. It consists of three vital steps including the selection of suitable cells, formation of 3d scaffolds, and adding growth factors. Mesenchymal stem cells (MSCs) and embryonic stem cells (ESCs) are mentioned as two main sources for this approach that have been used for the treatment of various types of disorders. However, the main focus of literature in the field of dental tissue engineering is on utilizing MSCs. On the other hand, biocompatible scaffolds play a notable role in this regenerative process which is mentioned to be harmless with acceptable osteoinductivity. Their ability in inhibiting inflammatory responses also makes them powerful tools. Indeed, stem cell functions should be supported by biomaterials acting as scaffolds incorporated with biological signals. Naturally derived polymeric scaffolds and synthetically engineered polymeric/ceramic scaffolds are two main types of scaffolds regarding their materials that are defined further in this review. Various strategies of tissue bioengineering can affect the regeneration of dentin-pulp complex, periodontium regeneration, and whole teeth bioengineering. In this regard, in vivo/ex vivo experimental models have been developed recently in order to perform preclinical studies of dental tissue engineering which make it more transferable to be used for clinic uses. This review summarizes dental tissue engineering through its different components. Also, strategies of tissue bioengineering and experimental models are introduced in order to provide a perspective of the potential roles of dental tissue engineering to be used for clinical aims.