Synergistic effects of carboxymethyl-hexanoyl chitosan, cationic polyurethane-short branch PEI in miR122 gene delivery: accelerated differentiation of iPSCs into mature hepatocyte-like cells and improved stem cell therapy in a hepatic failure model

Framework nucleic Acid-MicroRNA mediated hepatic differentiation and functional hepatic spheroid development for treating acute liver failure

The specific induction of hepatic differentiation presents a significant challenge in developing alternative liver cell sources and viable strategies for clinical therapy of acute liver failure (ALF). The past decade has witnessed the blossom of microRNAs in regenerative medicine. Herein, microRNA 122-functionalized tetrahedral framework nucleic acid (FNA-miR-122) has emerged as an unprecedented and potential platform for directing the hepatic differentiation of adipose-derived mesenchymal stem cells (ADMSCs), which offers a straightforward and cost-effective method for generating functional hepatocyte-like cells (FNA-miR-122-iHep). Additionally, we have successfully established a liver organoid synthesis strategy by optimizing the co-culture of FNA-miR-122-iHep with endothelial cells (HUVECs), resulting in functional Hep:HUE-liver spheroids. Transcriptome analysis not only uncovered the potential molecular mechanisms through which miR-122 influences hepatic differentiation in ADMSCs, but also clarified that Hep:HUE-liver spheroids could further facilitate hepatocyte maturation and improved tissue-specific functions, which may provide new hints to be used to develop a hepatic organoid platform. Notably, compared to transplanted ADMSCs and Hep-liver spheroid, respectively, both FNA-miR-122-iHep-based single cell therapy and Hep:HUE-liver spheroid-based therapy showed high efficacy in treating ALF in vivo. Collectively, this research establishes a robust system using microRNA to induce ADMSCs into functional hepatocyte-like cells and to generate hepatic organoids in vitro, promising a highly efficient therapeutic approach for ALF.

Exploring the roles of non-coding RNAs in liver regeneration

Liver regeneration (LR) is a complex process encompassing three distinct phases: priming, proliferation phase and restoration, all influenced by various regulatory factors. After liver damage or partial resection, the liver tissue demonstrates remarkable restorative capacity, driven by cellular proliferation and repair mechanisms. The essential roles of non-coding RNAs (ncRNAs), predominantly microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNA (circRNA), in regulating LR have been vastly studied. Additionally, the impact of ncRNAs on LR and their abnormal expression profiles during this process have been extensively documented. Mechanistic investigations have revealed that ncRNAs interact with genes involved in proliferation to regulate hepatocyte proliferation, apoptosis and differentiation, along with liver progenitor cell proliferation and migration. Given the significant role of ncRNAs in LR, an in-depth exploration of their involvement in the liver's self-repair capacity can reveal promising therapeutic strategies for LR and liver-related diseases. Moreover, understanding the unique regenerative potential of the adult liver and the mechanisms and regulatory factors of ncRNAs in LR are crucial for improving current treatment strategies and exploring new therapeutic approaches for various liver-related diseases. This review provides a brief overview of the LR process and the ncRNA expression profiles during this process. Furthermore, we also elaborate on the specific molecular mechanisms through which multiple key ncRNAs regulate the LR process. Finally, based on the expression characteristics of ncRNAs and their interactions with proliferation-associated genes, we explore their potential clinical application, such as developing predictive indicators reflecting liver regenerative activity and manipulating LR processes for therapeutic purposes.

PEI-based functional materials: Fabrication techniques, properties, and biomedical applications

Cationic polymers have recently attracted considerable interest as research breakthroughs for various industrial and biomedical applications. They are particularly interesting due to their highly positive charges, acceptable physicochemical properties, and ability to undergo further modifications, making them attractive candidates for biomedical applications. Polyethyleneimines (PEIs), as the most extensively utilized polymers, are one of the valuable and prominent classes of polycations. Owing to their flexible polymeric chains, broad molecular weight (MW) distribution, and repetitive structural units, their customization for functional composites is more feasible. The specific beneficial attributes of PEIs could be introduced by purposeful functionalization or modification, long service life, biocompatibility, and distinct geometry. Therefore, PEIs have significant potential in biotechnology, medicine, and bioscience. In this review, we present the advances in PEI-based nanomaterials, their transfection efficiency, and their toxicity over the past few years. Furthermore, the potential and suitability of PEIs for various applications are highlighted and discussed in detail. This review aims to inspire readers to investigate innovative approaches for the design and development of next-generation PEI-based nanomaterials possessing cutting-edge functionalities and appealing characteristics.

MicroRNA-122-functionalized DNA tetrahedron stimulate hepatic differentiation of human mesenchymal stem cells for acute liver failure therapy

As the most abundant liver-specific microRNA, microRNA-122 (miR122) played a crucial role in the differentiation of stem cells into hepatocytes. However, highly efficient miR122 delivery still confronts challenges including poor cellular uptake and easy biodegradation. Herein, we for the first time demonstrated that the tetrahedral DNA (TDN) nanoplatform had great potential in inducing the differentiation of human mesenchymal stem cells (hMSCs) into functional hepatocyte-like cells (HLCs) by transferring the liver-specific miR122 to hMSCs efficiently without any extrinsic factors. As compared with miR122, miR122-functionalized TDN (TDN-miR122) could significantly up-regulate the protein expression levels of mature hepatocyte markers and hepatocyte-specific marker genes in hMSCs, indicating that TDN-miR122 could particularly activate the hepatocyte-specific properties of hMSCs for developing cell-based therapies in vitro. The transcriptomic analysis further indicated the potential mechanism that TDN-miR122 assisted hMSCs differentiated into functional HLCs. The TDN-miR122-hMSCs exhibited hepatic cell morphology phenotype, significantly up-regulated specific hepatocyte genes and hepatic biofunctions in comparison with the undifferentiated MSCs. Preclinical in vivo transplantation appeared that TDN-miR122-hMSCs in combination with or without TDN could efficiently rescue acute liver failure injury through hepatocyte function supplement, anti-apoptosis, cellular proliferation promotion, and anti-inflammatory. Collectively, our findings may provide a new and facile approach for hepatic differentiation of hMSCs for acute liver failure therapy. Further large animal model explorations are needed to study their potential in clinical translation in the future.

The Efficiency of Stem Cells (SCs) Differentiation into Functional Hepatocytes for Treating Liver Disorders: A Systematic Review

Stem cells provided new opportunity to treat various diseases, including liver disorders. Stem cells are unspecialized cells, stimulating influential research interest be indebted to their multipotent self-renewal capacity and differentiation characteristics into several specialized cell types. Many factors contribute to their differentiation into different cell types such as insulin producing cells, osteoblast, and hepatocytes. Accordingly, wide range methods and materials have been used to transform stem cells into hepatocytes, but effectiveness of differentiation is different and depends on several factors such as cell-to-cell adhesion, cell-to-cell contact, and cell biological change. Search was done in PubMed, Scopus, and WOS to evaluate results of studies about stem cells differentiation for higher efficacy. Among more than 28000 papers, 51 studies were considered eligible for more evaluations. Results indicated that most studies were performed on mesenchymal stem cells compared with other types. Acute liver failure was the most investigated liver disorder, and tissue engineering was the most investigated differentiation methods. Also, functional parameters were the most evaluated parameters in assessing differentiation efficacy. We summarize recent advances in increasing efficiency of stem cells differentiation using varied materials, since promising results of this review, further studies are needed to assess efficiency and safety of these cells transplantation in some liver disease treatment.

Mir-122 upregulation and let-7f downregulation combination: The effects on hepatic differentiation of hiPSCs on the PCL-Gel-HA nanofibrous scaffold

Cell therapy and tissue engineering as promising candidates for the liver transplantation dilemma are of special interest. Induced pluripotent stem cells (iPSCs) are one of the best sources in this field, but their differentiation methods to hepatocytes have remained challenging. We transduced human iPSCs (hiPSCs) with miR-122 and off-let-7f (hiPSCs^{miR-122 + off-let-7f} ) to evaluate how they can differentiate hiPSCs to hepatocyte-like cells (HLCs) without any extrinsic growth factor. Additionally, we studied the effect of Poly ɛ-caprolactone-gelatin-hyaluronic acid (PCL-Gel-HA) nanofibrous scaffold as an extracellular matrix (ECM) simulator on differentiation improvement. Definitive endoderm markers (FOXA2 and SOX17), as well as hepatic markers (AFP, Albumin, CK18, HNF4α) expression, were significantly higher in hiPSCs^{miR-122 + off-let-7f} derived HLCs (hiPSCs-HLCs) compared to the control group (miR-scramble transduced hiPSCs: hiPSCs^scramble ). hiPSCs-HLCs indicated hepatocyte morphological characteristics and positive immunostaining for AFP, Albumin and HNF4α. Albumin and urea secretion were significantly higher in hiPSCs-HLCs than hiPSCs^scramble . Comparing these markers in the PCL-Gel-HA group with the tissue culture plate (TCP) group revealed that PCL-Gel-HA could improve differentiation towards HLCs significantly. Regarding our results, these microRNAs can be used to differentiate hiPSCs to the functional hepatocytes for disease modelling, drug screening and cell-based therapy in future studies.

Chitosan Based MicroRNA Nanocarriers

Vectorization of microRNAs has shown to be a smart approach for their potential delivery to treat many diseases (i.e., cancer, osteopathy, vascular, and infectious diseases). However, there are barriers to genetic in vivo delivery regarding stability, targeting, specificity, and internalization. Polymeric nanoparticles can be very promising candidates to overcome these challenges. One of the most suitable polymers for this purpose is chitosan. Chitosan (CS), a biodegradable biocompatible natural polysaccharide, has always been of interest for drug and gene delivery. Being cationic, chitosan can easily form particles with anionic polymers to encapsulate microRNA or even complex readily forming polyplexes. However, fine tuning of chitosan characteristics is necessary for a successful formulation. In this review, we cover all chitosan miRNA formulations investigated in the last 10 years, to the best of our knowledge, so that we can distinguish their differences in terms of materials, formulation processes, and intended applications. The factors that make some optimized systems superior to their predecessors are also discussed to reach the highest potential of chitosan microRNA nanocarriers.

Current Status and Challenges of Human Induced Pluripotent Stem Cell-Derived Liver Models in Drug Discovery

The pharmaceutical industry is in high need of efficient and relevant in vitro liver models, which can be incorporated in their drug discovery pipelines to identify potential drugs and their toxicity profiles. Current liver models often rely on cancer cell lines or primary cells, which both have major limitations. However, the development of human induced pluripotent stem cells (hiPSCs) has created a new opportunity for liver disease modeling, drug discovery and liver toxicity research. hiPSCs can be differentiated to any cell of interest, which makes them good candidates for disease modeling and drug discovery. Moreover, hiPSCs, unlike primary cells, can be easily genome-edited, allowing the creation of reporter lines or isogenic controls for patient-derived hiPSCs. Unfortunately, even though liver progeny from hiPSCs has characteristics similar to their in vivo counterparts, the differentiation of iPSCs to fully mature progeny remains highly challenging and is a major obstacle for the full exploitation of these models by pharmaceutical industries. In this review, we discuss current liver-cell differentiation protocols and in vitro iPSC-based liver models that could be used for disease modeling and drug discovery. Furthermore, we will discuss the challenges that still need to be overcome to allow for the successful implementation of these models into pharmaceutical drug discovery platforms.

Rapid and efficient generation of cartilage pellets from mouse induced pluripotent stem cells by transcriptional activation of BMP-4 with shaking culture

Induced pluripotent stem cells (iPSCs) offer an unlimited source for cartilage regeneration as they can generate a wide spectrum of cell types. Here, we established a tetracycline (tet) controlled bone morphogenetic protein-4 (BMP-4) expressing iPSC (iPSC-Tet/BMP-4) line in which transcriptional activation of BMP-4 was associated with enhanced chondrogenesis. Moreover, we developed an efficient and simple approach for directly guiding iPSC-Tet/BMP-4 differentiation into chondrocytes in scaffold-free cartilaginous pellets using a combination of transcriptional activation of BMP-4 and a 3D shaking suspension culture system. In chondrogenic induction medium, shaking culture alone significantly upregulated the chondrogenic markers Sox9, Col2a1, and Aggrecan in iPSCs-Tet/BMP-4 by day 21. Of note, transcriptional activation of BMP-4 by addition of tet (doxycycline) greatly enhanced the expression of these genes. The cartilaginous pellets derived from iPSCs-Tet/BMP-4 showed an oval morphology and white smooth appearance by day 21. After day 21, the cells presented a typical round morphology and the extracellular matrix was stained intensively with Safranin O, alcian blue, and type II collagen. In addition, the homogenous cartilaginous pellets derived from iPSCs-Tet/BMP-4 with 28 days of induction repaired joint osteochondral defects in immunosuppressed rats and integrated well with the adjacent host cartilage. The regenerated cartilage expressed the neomycin resistance gene, indicating that the newly formed cartilage was generated by the transplanted iPSCs-Tet/BMP-4. Thus, our culture system could be a useful tool for further investigation of the mechanism of BMP-4 in regulating iPSC differentiation toward the chondrogenic lineage, and should facilitate research in cartilage development, repair, and osteoarthritis.

Genetically-Modified Stem Cell in Regenerative Medicine and Cancer Therapy; A New Era

Recently, genetic engineering by various strategies to stimulate gene expression in a specific and controllable mode is a speedily growing therapeutic approach. Genetic modification of human stem or progenitor cells, such as embryonic stem cells (ESCs), neural progenitor cells (NPCs), mesenchymal stem/stromal cells (MSCs), and hematopoietic stem cells (HSCs) for direct delivery of specific therapeutic molecules or genes has been evidenced as an opportune plan in the context of regenerative medicine due to their supported viability, proliferative features, and metabolic qualities. On the other hand, a large number of studies have investigated the efficacy of modified stem cells in cancer therapy using cells from various sources, disparate transfection means for gene delivery, different transfected yields, and wide variability of tumor models. Accordingly, cell-based gene therapy holds substantial aptitude for the treatment of human malignancy as it could relieve signs or even cure cancer succeeding expression of therapeutic or suicide transgene products; however, there exist inconsistent results in this regard. Herein, we deliver a brief overview of stem cell potential to use in cancer therapy and regenerative medicine and importantly discuss stem cells based gene delivery competencies to stimulate tissue repair and replacement in concomitant with their potential to use as an anti-cancer therapeutic strategy, focusing on the last two decades in vivo studies.

Sinking Our Teeth in Getting Dental Stem Cells to Clinics for Bone Regeneration

Dental stem cells have been isolated from the medical waste of various dental tissues. They have been characterized by numerous markers, which are evaluated herein and differentiated into multiple cell types. They can also be used to generate cell lines and iPSCs for long-term in vitro research. Methods for utilizing these stem cells including cellular systems such as organoids or cell sheets, cell-free systems such as exosomes, and scaffold-based approaches with and without drug release concepts are reported in this review and presented with new pictures for clarification. These in vitro applications can be deployed in disease modeling and subsequent pharmaceutical research and also pave the way for tissue regeneration. The main focus herein is on the potential of dental stem cells for hard tissue regeneration, especially bone, by evaluating their potential for osteogenesis and angiogenesis, and the regulation of these two processes by growth factors and environmental stimulators. Current in vitro and in vivo publications show numerous benefits of using dental stem cells for research purposes and hard tissue regeneration. However, only a few clinical trials currently exist. The goal of this review is to pinpoint this imbalance and encourage scientists to pick up this research and proceed one step further to translation.

Advancements in stem cell-derived hepatocyte-like cell models for hepatotoxicity testing

Drug-induced liver injury (DILI) is one of the leading causes of clinical trial failures and high drug attrition rates. Currently, the commonly used hepatocyte models include primary human hepatocytes (PHHs), animal models, and hepatic cell lines. However, these models have disadvantages that include species-specific differences or inconvenient cell extraction methods. Therefore, a novel, inexpensive, efficient, and accurate model that can be applied to drug screening is urgently needed. Owing to their self-renewable ability, source abundance, and multipotent competence, stem cells are stable sources of drug hepatotoxicity screening models. Because 3D culture can mimic the in vivo microenvironment more accurately than can 2D culture, the former is commonly used for hepatocyte culture and drug screening. In this review, we introduce the different sources of stem cells used to generate hepatocyte-like cells and the models for hepatotoxicity testing that use stem cell-derived hepatocyte-like cells.

Applications of Nanobiomaterials in the Therapy and Imaging of Acute Liver Failure

This review focuses on the therapeutic mechanisms, targeting strategies of various nanomaterials in acute liver failure, and recent advances of diverse nanomaterials for acute liver failure therapy, diagnosis, and imaging. This review provides an outlook on the applications of nanomaterials, especially on the new horizons in acute liver failure therapy, and inspires broader interests across various disciplines. Acute liver failure (ALF), a fatal clinical disease featured with overwhelming hepatocyte necrosis, is a grand challenge in global health. However, a satisfactory therapeutic option for curing ALF is still absent, other than liver transplantation. Nanobiomaterials are currently being developed for the diagnosis and treatment of ALF. The liver can sequester most of nanoparticles from blood circulation, which becomes an intrinsic superiority for nanobiomaterials targeting hepatic diseases. Nanobiomaterials can enhance the bioavailability of free drugs, thereby significantly improving the therapeutic effects in ALF. Nanobiomaterials can also increase the liver accumulation of therapeutic agents and enable more effective targeting of the liver or specific liver cells. In addition, stimuli-responsive, optical, or magnetic nanomaterials exhibit great potential in the therapeutical, diagnostic, and imaging applications in ALF. Therefore, therapeutic agents in combination with nanobiomaterials increase the specificity of ALF therapy, diminish adverse systemic effects, and offer a multifunctional theranostic platform. Nanobiomaterial holds excellent significance and prospects in ALF theranostics. In this review, we summarize the therapeutic mechanisms and targeting strategies of various nanobiomaterials in ALF. We highlight recent developments of diverse nanomedicines for ALF therapy, diagnosis, and imaging. Furthermore, the challenges and future perspectives in the theranostics of ALF are also discussed.

Chitosan for gene delivery: Methods for improvement and applications

Gene therapy is a promising strategy for treating challenging diseases. The successful delivery of genes is a critical step for gene therapy. However, concerns about immunogenicity and toxicity are the main obstacles against the widespread use of effective viral systems. Therefore, nonviral vectors are regarded as good alternatives to viral vectors. Chitosan is a natural cationic polysaccharide that could be used to create nonviral gene delivery vectors. Various methods have been developed to improve the properties of chitosan related to gene delivery. This review introduces the features of chitosan in gene delivery, summarizes current progress toward methods promoting the properties of chitosan related to gene delivery, and presents different applications of chitosan in gene delivery vectors. Finally, future prospects of gene vectors based on chitosan are discussed.

Treatment of AECHB and Severe Hepatitis (Liver Failure)

This chapter describes the general treatment and immune principles and internal management for AECHB and HBV ACLF, including ICU monitoring, general supportive medications/nutrition/nursing, immune therapy, artificial liver supportive systems, hepatocyte/stem cell, and liver transplant, management for special populations, frequently clinical complications and the utilization of Chinese traditional medicines.

Early clinical indicators of severe hepatitis B include acratia, gastrointestinal symptoms, a daily increase in serum bilirubin >1 mg/dL, toxic intestinal paralysis, bleeding tendency and mild mind anomaly or character change, and the presence of other diseases inducing severe hepatitis. Laboratory indicators include T-Bil, PTA, cholinesterase, pre-albumin and albumin. The roles of immune indicators (such as IL-6, TNF-α, and fgl2), gene polymorphisms, HBV genotypes, and gene mutations as early clinical indicators.

Intensive Care Unit monitor patients with severe hepatitis include intracranial pressure, infection, blood dynamics, respiratory function, renal function, blood coagulation function, nutritional status and blood purification process. Nursing care should not only include routine care, but psychological and special care (complications).

Nutrition support and nursing care should be maintained throughout treatment for severe hepatitis. Common methods of evaluating nutritional status include direct human body measurement, creatinine height index (CHI) and subject global assessment of nutrition (SGA). Malnourished patients should receive enteral or parenteral nutrition support.

Immune therapies for severe hepatitis include promoting hepatocyte regeneration (e.g. with glucagon, hepatocyte growth factor and prostaglandin E1), glucocorticoid suppressive therapy, and targeting molecular blocking. Corticosteroid treatment should be early and sufficient, and adverse drug reactions monitored. Treatments currently being investigated are those targeting Toll-like receptors, NK cell/NK cell receptors, macrophage/immune coagulation system, CTLA-4/PD-1 and stem cell transplantation.

In addition to conventional drugs and radioiodine, corticosteroids and artificial liver treatment can also be considered for severe hepatitis patients with hyperthyreosis. Patients with gestational severe hepatitis require preventive therapy for fetal growth restriction, and it is necessary to choose the timing and method of fetal delivery. For patients with both diabetes and severe hepatitis, insulin is preferred to oral antidiabetic agents to control blood glucose concentration. Liver toxicity of corticosteroids and immune suppressors should be monitored during treatment for severe hepatitis in patients with connective tissue diseases including SLE, RA and sicca syndrome. Patient with connective tissue diseases should preferably be started after the antiviral treatment with nucleos(t)ide analogues.

An artificial liver can improve patients’ liver function; remove endotoxins, blood ammonia and other toxins; correct amino acid metabolism and coagulation disorders; and reverse internal environment imbalances. Non-bioartificial livers are suitable for patients with early and middle stage severe hepatitis; for late-stage patients waiting for liver transplantation; and for transplanted patients with rejection reaction or transplant failure. The type of artificial liver should be determined by each patient’s condition and previous treatment purpose, and patients should be closely monitored for adverse reactions and complications. Bio- and hybrid artificial livers are still under development.

MELD score is the international standard for choosing liver transplantation. Surgical methods mainly include the in situ classic type and the piggyback type; transplantation includes no liver prophase, no liver phase or new liver phase. Preoperative preparation, management of intraoperative and postoperative complications and postoperative long-term treatment are keys to success.

Severe hepatitis belongs to the categories of “acute jaundice”, “scourge jaundice”, and “hot liver” in traditional Chinese medicine. Treatment methods include Chinese traditional medicines, acupuncture and acupoint injection, external application of drugs, umbilical compress therapy, drip, blow nose therapy, earpins, and clysis. Dietary care is also an important part of traditional Chinese medicine treatment.

Non-viral nanocarriers for intracellular delivery of microRNA therapeutics

MicroRNAs are small regulatory noncoding RNAs that regulate various biological processes. Herein, we will present the development of the strategies for intracellular miRNAs delivery, and specially focus on the rational designed routes, their mechanisms of action, as well as potential therapeutics used in the host cells orin vivostudies.

Localised non-viral delivery of nucleic acids for nerve regeneration in injured nervous systems

Axons damaged by traumatic injuries are often unable to spontaneously regenerate in the adult central nervous system (CNS). Although the peripheral nervous system (PNS) has some regenerative capacity, its ability to regrow remains limited across large lesion gaps due to scar tissue formation. Nucleic acid therapy holds the potential of improving regeneration by enhancing the intrinsic growth ability of neurons and overcoming the inhibitory environment that prevents neurite outgrowth. Nucleic acids modulate gene expression by over-expression of neuronal growth factor or silencing growth-inhibitory molecules. Although in vitro outcomes appear promising, the lack of efficient non-viral nucleic acid delivery methods to the nervous system has limited the application of nucleic acid therapeutics to patients. Here, we review the recent development of efficient non-viral nucleic acid delivery platforms, as applied to the nervous system, including the transfection vectors and carriers used, as well as matrices and scaffolds that are currently used. Additionally, we will discuss possible improvements for localised nucleic acid delivery.

Polyethylenimine-based nanocarriers in co-delivery of drug and gene: a developing horizon

The meaning of gene therapy is the delivery of DNA or RNA to cells for the treatment or prevention of genetic disorders. The success rate of gene therapy depends on the progression and safe gene delivery system. The vectors available for gene therapy are divided into viral and non-viral systems. Viral vectors cause higher transmission efficiency and long gene expression, but they have major problems, such as immunogenicity, carcinogenicity, the inability to transfer large size genes and high costs. Non-viral gene transfer vectors have attracted more attention because they exhibit less toxicity and the ability to transfer large size genes. However, the clinical application of non-viral methods still faces some limitations, including low transmission efficiency and poor gene expression. In recent years, numerous methods and gene-carriers have been developed to improve gene transfer efficiency. The use of Polyethylenimine (PEI) based transfer of collaboration may create a new way of treating diseases and the combination of chemotherapy and gene therapy. The purpose of this paper is to introduce the PEI as an appropriate vector for the effective gene delivery.

Non-viral gene delivery systems for tissue repair and regeneration

Critical tissue defects frequently result from trauma, burns, chronic wounds and/or surgery. The ideal treatment for such tissue loss is autografting, but donor sites are often limited. Tissue engineering (TE) is an inspiring alternative for tissue repair and regeneration (TRR). One of the current state-of-the-art methods for TRR is gene therapy. Non-viral gene delivery systems (nVGDS) have great potential for TE and have several advantages over viral delivery including lower immunogenicity and toxicity, better cell specificity, better modifiability, and higher productivity. However, there is no ideal nVGDS for TRR, hence, there is widespread research to improve their properties. This review introduces the basic principles and key aspects of commonly-used nVGDSs. We focus on recent advances in their applications, current challenges, and future directions.

Improvement of non-alcoholic steatohepatitis by hepatocyte-like cells generated from iPSCs with Oct4/Sox2/Klf4/Parp1

The prevalence of nonalcoholic fatty liver disease (NAFLD) is usually increased with age. Non-alcoholic steatohepatitis (NASH), a serious form of NAFLD, may lead to cirrhosis and end-stage liver diseases. Induced pluripotent stem cells (iPSCs) hold promising potential in personalized medicine. Although obviation of c-Myc reduces tumorigenic risk, it also largely reduced the generation of iPSCs. Recently, Poly(ADP-ribose) polymerase 1 (Parp1) has been reported to enhance cell reprogramming. In this study, we demonstrated that forced expression of Oct4/Sox2/Klf4/Parp1 (OSKP) effectively promoted iPSC generation from senescent somatic cells from 18-month-old mouse. The iPSCs presented regular pluripotent properties, ability to form smaller teratoma with smaller size, and the potential for tridermal differentiation including hepatocyte-like cells (OSKP-iPSC-Heps). Resembled to fetal hepatocytes but not senescent hepatocytes, these OSKP-iPSC-Heps possessed antioxidant ability and were resistant to oxidative insult induced by H₂O₂ or exogenous fatty acid. Intrasplenic transplantation of OSKP-iPSC-Heps ameliorated the triglyceride over-accumulation and hepatitis, prevented the production of inflammatory cytokines and oxidative substances, and reduced apoptotic cells in methionine/choline-deficient diet (MCDD)-fed mice. In conclusion, we demonstrated that Parp-1 promoted iPSC generation from senescent cells, which can be used for the treatment of NASH after hepatic-specific differentiation. These findings indicated that patient-derived iPSC-Heps may offer an alternative option for treatment of NASH and NASH-associated end-stage liver diseases.

A decade of progress in liver regenerative medicine

Liver diseases can be caused by viral infection, metabolic disorder, alcohol consumption, carcinoma or injury, chronically progressing to end-stage liver disease or rapidly resulting in acute liver failure. In either situation, liver transplantation is most often sought for life saving, which is, however, significantly limited by severe shortage of organ donors. Until now, tremendous multi-disciplinary efforts have been dedicated to liver regenerative medicine, aiming at providing transplantable cells, microtissues, or bioengineered whole liver via tissue engineering, or maintaining partial liver functions via extracorporeal support. In both directions, new compatible biomaterials, stem cell sources, and bioengineering approaches have fast-forwarded liver regenerative medicine towards potential clinical applications. Another important progress in this field is the development of liver-on-a-chip technologies, which enable tissue engineering, disease modeling, and drug testing under biomimetic extracellular conditions. In this review, we aim to highlight the last decade's progress in liver regenerative medicine from liver tissue engineering, bioartificial liver devices (BAL), to liver-on-a-chip platforms, and then to present challenges ahead for further advancement.

Therapeutic effects of hepatocyte growth factor-overexpressing dental pulp stem cells on liver cirrhosis in a rat model

Cirrhosis is the terminal stage of hepatic diseases and is prone to develop into hepatocyte carcinoma. Increasing evidence suggests that the transplantation of dental pulp stem cells (DPSCs) may promote recovery from cirrhosis, but the key regulatory mechanisms involved remain to be determined. In this study, we overexpressed human hepatocyte growth factor (hHGF) in primary rat DPSCs and evaluated the effects of HGF overexpression on the biological behaviors and therapeutic efficacy of grafted DPSCs in cirrhosis. Liver cirrhosis was induced via the intraperitoneal injection of CCl₄ twice weekly for 12 weeks and was verified through histopathological and serological assays. HGF was overexpressed in DPSCs via transduction with a hHGF-lentiviral vector and confirmed based on the elevated expression and secretion of HGF. The HGF-overexpressing DPSCs were transplanted into rats intravenously. The HGF-overexpressing DPSCs showed increased survival and hepatogenic differentiation in host liver tissue at 6 weeks after grafting. They also exhibited a significantly greater repair potential in relation to cirrhosis pathology and impaired liver function than did DPSCs expressing HGF at physiological levels. Our study may provide an experimental basis for the development of novel methods for the treatment of liver cirrhosis in clinical practice.

Local co-administration of gene-silencing RNA and drugs in cancer therapy: State-of-the art and therapeutic potential

Gene-silencing miRNA and siRNA are emerging as attractive therapeutics with potential to suppress any genes, which could be especially useful in combination cancer therapy to overcome multidrug resistant (MDR) cancer. Nanomedicine aims to advance cancer treatment through functional nanocarriers that delivers one or more therapeutics to cancer tissue and cells with minimal off-target effects and suitable release kinetics and dosages. Although much effort has gone into developing circulating nanocarriers with targeting functionality for systemic administration, another alternative and straightforward approach is to utilize formulations to be administered directly to the site of action, such as pulmonary and intratumoral delivery. The combination of gene-silencing RNA with drugs in nanocarriers for localized delivery is emerging with promising results. In this review, the current progress and strategies for local co-administration of RNA and drug for synergistic effects and future potential in cancer treatment are presented and discussed. Key advances in RNA-drug anticancer synergy and localized delivery systems were combined with a review of the available literature on local co-administration of RNA and drug for cancer treatment. It is concluded that advanced delivery systems for local administration of gene-silencing RNA and drug hold potential in treatment of cancer, depending on indication. In particular, there are promising developments using pulmonary delivery and intratumoral delivery in murine models, but further research should be conducted on other local administration strategies, designs that achieve effective intracellular delivery and maximize synergy and feasibility for clinical use.

Stem cell-derived models to improve mechanistic understanding and prediction of human drug-induced liver injury

Current preclinical drug testing does not predict some forms of adverse drug reactions in humans. Efforts at improving predictability of drug-induced tissue injury in humans include using stem cell technology to generate human cells for screening for adverse effects of drugs in humans. The advent of induced pluripotent stem cells means that it may ultimately be possible to develop personalized toxicology to determine interindividual susceptibility to adverse drug reactions. However, the complexity of idiosyncratic drug-induced liver injury means that no current single-cell model, whether of primary liver tissue origin, from liver cell lines, or derived from stem cells, adequately emulates what is believed to occur during human drug-induced liver injury. Nevertheless, a single-cell model of a human hepatocyte which emulates key features of a hepatocyte is likely to be valuable in assessing potential chemical risk; furthermore, understanding how to generate a relevant hepatocyte will also be critical to efforts to build complex multicellular models of the liver. Currently, hepatocyte-like cells differentiated from stem cells still fall short of recapitulating the full mature hepatocellular phenotype. Therefore, we convened a number of experts from the areas of preclinical and clinical hepatotoxicity and safety assessment, from industry, academia, and regulatory bodies, to specifically explore the application of stem cells in hepatotoxicity safety assessment and to make recommendations for the way forward. In this short review, we particularly discuss the importance of benchmarking stem cell-derived hepatocyte-like cells to their terminally differentiated human counterparts using defined phenotyping, to make sure the cells are relevant and comparable between labs, and outline why this process is essential before the cells are introduced into chemical safety assessment. (Hepatology 2017;65:710-721).

High transfection efficiency promoted by tailor-made cationic tri-block copolymer-based nanoparticles

Cationic polymer-based vectors have been considered a promising strategy in gene therapy area due to their inherent ability to condense genetic material and successfully transfect cells. However, they usually exhibit high cytotoxicity. In this work, it is proposed the use of a tailor-made gene carrier based on a tri-block copolymer of poly[2-(dimethylamino)ethyl methacrylate] and poly(β-amino ester) (PDMAEMA-b-PβAE-b-PDMAEMA), the influence of the PβAE length being assessed. For this purpose, three different block copolymers were prepared varying the molecular weight of this segment. The obtained materials were characterized by NMR and SEC analyzes. Different polyplexes formulations were prepared and evaluated in terms of physicochemical characterization (ethidium bromide intercalation assay, agarose gel electrophoresis assay, dynamic light scattering, zeta potential analyzes and atomic force microscopy) and biological activity (cytotoxicity, and luciferase and green fluorescent protein expression in Hela and COS-7 cell lines). Among the developed nanosystems, the best polyplex formulation revealed between 40- and 60-fold higher transgene expression, in HeLa and COS-7 cell lines, and much lower cytotoxicity than that observed with branched PEI and TurboFect™. Moreover, these nanosystems present suitable physicochemical properties for gene delivery namely reduced mean diameter and high DNA protection. The results reported here show the enormous potential of this block copolymer as gene carrier.

STATEMENT OF SIGNIFICANCE

Syntheses of PDMAEMA-b-PβAE-b-PDMAEMA block copolymers for an extremely effective non-viral vector. The block copolymer PDMAEMA₃₀₀₀-b-PβAE₁₂₀₀₀-b-PDMAEMA₃₀₀₀-based polyplexes at 100/1N/P ratio exhibits between 40- and 60-fold higher transgene expression in HeLa and COS-7 cell lines than commonly used polymeric non-viral vectors, namely branched PEI (known as the gold standard) and TurboFect™ (commercial available).

Recent progress in nanotechnology for stem cell differentiation, labeling, tracking and therapy

Nanotechnology advancements for stem cell differentiation, labeling, tracking and therapeutic applications in cardiac repair, bone, and liver regeneration are delineated.

miRNA nanotherapeutics for cancer

MicroRNAs (miRNAs) are noncoding RNA molecules that regulate gene expression through diverse mechanisms. Increasing evidence suggests that miRNA-based therapies, either restoring or repressing miRNA expression and activity, hold great promise. However, the efficient delivery of miRNAs to target tissues is a major challenge in the transition of miRNA therapy to the clinic. Cationic polymers or viral vectors are efficient delivery agents but their systemic toxicity and immunogenicity limit their clinical usage. Efficient targeting and sustained release of miRNAs/anti-miRNAs using nanoparticles (NPs) conjugated with antibodies and/or peptides could reduce the required therapeutic dosage while minimizing systemic and cellular toxicity. Given their importance in clinical oncology, here we focus on the development of miRNA nanoformulations to achieve enhanced cellular uptake, bioavailability, and accumulation at the tumor site.

Two Effective Routes for Removing Lineage Restriction Roadblocks: From Somatic Cells to Hepatocytes

The conversion of somatic cells to hepatocytes has fundamentally re-shaped traditional concepts regarding the limited resources for hepatocyte therapy. With the various induced pluripotent stem cell (iPSC) generation routes, most somatic cells can be effectively directed to functional stem cells, and this strategy will supply enough pluripotent material to generate promising functional hepatocytes. However, the major challenges and potential applications of reprogrammed hepatocytes remain under investigation. In this review, we provide a summary of two effective routes including direct reprogramming and indirect reprogramming from somatic cells to hepatocytes and the general potential applications of the resulting hepatocytes. Through these approaches, we are striving toward the goal of achieving a robust, mature source of clinically relevant lineages.

In vitro culture of isolated primary hepatocytes and stem cell-derived hepatocyte-like cells for liver regeneration

Various liver diseases result in terminal hepatic failure, and liver transplantation, cell transplantation and artificial liver support systems are emerging as effective therapies for severe hepatic disease. However, all of these treatments are limited by organ or cell resources, so developing a sufficient number of functional hepatocytes for liver regeneration is a priority. Liver regeneration is a complex process regulated by growth factors (GFs), cytokines, transcription factors (TFs), hormones, oxidative stress products, metabolic networks, and microRNA. It is well-known that the function of isolated primary hepatocytes is hard to maintain; when cultured in vitro, these cells readily undergo dedifferentiation, causing them to lose hepatocyte function. For this reason, most studies focus on inducing stem cells, such as embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), hepatic progenitor cells (HPCs), and mesenchymal stem cells (MSCs), to differentiate into hepatocyte-like cells (HLCs) in vitro. In this review, we mainly focus on the nature of the liver regeneration process and discuss how to maintain and enhance in vitro hepatic function of isolated primary hepatocytes or stem cell-derived HLCs for liver regeneration. In this way, hepatocytes or HLCs may be applied for clinical use for the treatment of terminal liver diseases and may prolong the survival time of patients in the near future.

Lin28B/Let-7 Regulates Expression of Oct4 and Sox2 and Reprograms Oral Squamous Cell Carcinoma Cells to a Stem-like State

Lin28, a key factor for cellular reprogramming and generation of induced pluripotent stem cell (iPSC), makes a critical contribution to tumorigenicity by suppressing Let-7. However, it is unclear whether Lin28 is involved in regulating cancer stem-like cells (CSC), including in oral squamous carcinoma cells (OSCC). In this study, we demonstrate a correlation between high levels of Lin28B, Oct4, and Sox2, and a high percentage of CD44(+)ALDH1(+) CSC in OSCC. Ectopic Lin28B expression in CD44(-)ALDH1(-)/OSCC cells was sufficient to enhance Oct4/Sox2 expression and CSC properties, whereas Let7 co-overexpression effectively reversed these phenomena. We identified ARID3B and HMGA2 as downstream effectors of Lin28B/Let7 signaling in regulating endogenous Oct4 and Sox2 expression. Let7 targeted the 3' untranslated region of ARID3B and HMGA2 and suppressed their expression, whereas ARID3B and HMGA2 increased the transcription of Oct4 and Sox2, respectively, through promoter binding. Chromatin immunoprecipitation assays revealed a direct association between ARID3B and a specific ARID3B-binding sequence in the Oct4 promoter. Notably, by modulating Oct4/Sox2 expression, the Lin28B-Let7 pathway not only regulated stemness properties in OSCC but also determined the efficiency by which normal human oral keratinocytes could be reprogrammed to iPSC. Clinically, a Lin28B(high)-Let7(low) expression pattern was highly correlated with high levels of ARID3B, HMGA2, OCT4, and SOX2 expression in OSCC specimens. Taken together, our results show how Lin28B/Let7 regulates key cancer stem-like properties in oral squamous cancers.